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Issue n°26 - May 2014

Issue n°26 - May 2014
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In this issue

This IMBER Update focuses on IMBER´s longest running regional programme, Ecosystem Studies of Sub-Arctic Seas (ESSAS). It started under the auspices of GLOBEC to identify priorities for a planned research initiative for the Bering Sea, and to develop comparative studies of the marine ecosystems of the sub-arctic seas. Since those early days, the nuts and bolts of ESSAS, its working groups, have increased in number and evolved, from developing modelling strategies for comparisons and producing scenarios under climate change, to having a much broader focus that includes the bioenergetics and human dimension of this region. 

The first article, by the ESSAS co-Chairs, provides an overview of ESSAS and the work currently being undertaken by its working groups. Most of the articles that follow were presented at the recent ESSAS Annual Science Meeting and the associated workshops.

The article by Pavel Tishchenko, IMBER’s national contact in Russia, discusses possible causes of the anoxia in the marine biosphere reserve in Peter the Great Bay in the Japan Sea. The “Ocean colour for climate” article highlights new ocean colour products designed specifically for climate research, by improving the accuracy of ocean colour measurements. Read more about this initiative and where to access the data sets.

We hope that you will enjoy reading this issue of IMBER Update!

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Introduction to ESSAS

K. Drinkwater1, Franz Mueter2 and Sei-Ichi Saitoh3 – ESSAS Co-Chairs

1Institute of Marine Research, Bergen, Norway
2University of Alaska Fairbanks, School of Fisheries and Ocean Sciences, Juneau, AK, USA 
3Hokkaido University, Faculty of Fisheries Sciences, Hakodate, Hokkaido, Japan

 

The IMBER Regional Programme “Ecosystem Studies of Sub-Arctic Seas” (ESSAS) was first established in 2005 as a GLOBEC programme to address the need to understand how climate variability and change affects marine ecosystems of subarctic seas and their sustainability. Sub-Arctic seas became the focus because they support stocks of commercial fish that generate a major portion of the fish landings in the nations bordering them, as well as supporting subsistence fishers along their coasts, and vast numbers of marine birds and mammals. Climate-forced changes in these systems have had, and will continue to have, major economic and societal impacts due to anthropogenic climate change. In 2009, ESSAS transitioned from GLOBEC to IMBER and has continued its program on the Sub-Arctic of the Atlantic and Pacific oceans and in recent years has spread its activities poleward into the Arctic. ESSAS is guided by a Scientific Steering Committee that is presently comprised of 11 scientists from 8 different countries that meet once a year (Fig. 1).

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Figure 1.  The ESSAS SSC during the 2014 meeting in Copenhagen’s Botanical Garden near the meeting venue at the Natural History Museum of Denmark.

At its inception, ESSAS held an Open Science Meeting (OSM) in Victoria, Canada (Hunt et al., 2007), which was meant to be a guidepost of where we were in terms of our understanding of marine ecosystems of Sub-Arctic Seas. A second ESSAS OSM entitled “Comparative studies of climate effects on polar and sub-polar ocean ecosystems: progress in observation and prediction” was held in 2011 in Seattle, WA, USA. This provided an opportunity to showcase the progress that had been made within ESSAS and to identify remaining knowledge gaps and future research needs (Drinkwater et al., 2012).

 

Much of the ESSAS science is conducted by its five working groups. These include: the WG on Modelling Ecosystem Response (WGMER) that is currently compiling a special volume on ecosystem modelling dedicated to our late colleague, Bern Megrey; the WG on Arctic-Subarctic Interactions (WGASI) that investigates the effects of exchanges between the Arctic and the Subarctic, including the fate of water properties and organisms that are exchanged; the WG on Bioenergetics of Subarctic Fishes (WGBIOEN) works, primarily through the use of bioenergetic models, towards a deeper understanding of the climate’s impact on the spatial and temporal overlap between juvenile fish and their prey and its implications on possible future production; the WG on Human Dimensions (WGHUMD) examines the interaction between changes in the natural ecosystem and humans; and the WG on Comparative Paleo-Ecology in Sub-Arctic Seas (WGCPESAS) is interested in the ecosystem services which provide food for people and the role of climate on human settlements within ecosystems. These working groups hold special sessions or workshops focusing on particular topics of interest at the ESSAS Annual Science Meetings (ASMs). Our 2014 ASM was recently held at the Natural History Museum of Denmark in Copenhagen. In addition to a session on local research highlights from the host country, which has become an ESSAS tradition at the ASMs, the Copenhagen meeting included a special session sponsored by WGCPESAS. Research focussed on settlements in the Kuril and Aleutian islands in the Pacific and the Viking expansion and settlements in the Atlantic and fostered discussions about past variability in the subarctic (see report by Ben Fitzhugh below). A special session was also held on polar cods (Boreogadus saida and Arctogadus glacialis) that are key trophic links in Arctic ecosystems and range throughout the Arctic and into all of the subarctic seas (see report by Franz Mueter below). To our knowledge these were the first international workshops on these particular subjects. Many of the following articles are based on presentations at the 2014 ASM.   

Next year ESSAS will hold their ASM during June in Seattle, Washington, USA.  We are aiming for a special session on sea ice and its effects on the marine physics, chemistry and biology of subarctic and Arctic seas, and are also planning sessions on human dimensions aspects and bioenergetics.  Details of next year’s meeting and the report of this year’s meeting will appear on the ESSAS website (http://www.imr.no/essas/en) in the near future. 

  

     

References

  • Hunt, G., Drinkwater, K.F., McKinnell, S. & Mackas, D. (Eds.). 2007. Climate Variability and Subarctic Marine Ecosystems. Proceedings of the GLOBEC Symposium, held in Victoria, Canada, 16-20 May, 2005. Deep-Sea Research II 54: 2453-2970. 
  • Drinkwater, K.F., Hunt, G.L. Jr., Astthorsson, O.S. & Head, E.J.H (Eds.). 2012. Comparative Studies of Climate Effects on Polar and Sub-polar Ocean Ecosystems: Progress in Observation and Prediction.  Proceedings of the 2nd ESSAS Open Science Meeting, held in Seattle, USA, 22-26 May, 2011. ICES Journal of Marine Science 69: 1119-1328. 
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Science Highlights from ESSAS

International workshop on the ecology of Arctic gadids

Franz J. Mueter1, Jasmine Nahrgang2, R. John Nelson3

1School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Juneau, Alaska, USA; fmueter@alaska.edu 
2UiT- The Arctic University of Norway, Tromsø, Norway
3University of Victoria, British Columbia, Canada

 

An international workshop on the ecology of circumpolar Arctic gadids (Boreogadus saida and Arctogadus spp.) was convened during the ESSAS Annual Science Meeting on April 8-9 in Copenhagen, Denmark, with over 60 scientists from 10 countries. Presentations highlighted recent advances in our understanding of the ecology of these important species, which occupy a central role in Arctic marine food webs. All references in this article refer to workshop presentations; abstracts and selected presentations will be made available at the ESSAS website (http://www.imr.no/essas).

While research on B. saida has a long history, particularly in Russia (Karamushko and Christiansen), interest in Arctic marine ecosystems has grown in recent years as summer sea ice cover has diminished and water temperatures have increased.

Both B. saida, hereafter referred to as Polar cod, and Arctogadus spp. are cold-adapted and have antifreeze glycoproteins, which are required to survive long periods at sub-zero temperatures but come at a metabolic cost (Karamushko and Christiansen). The geographic distribution of B. saida extends throughout the Arctic and into the subarctic seas (Fig. 2), while Arctogadus spp. are restricted to higher latitudes (Madsen et al., Bouchard et al.). The distribution of Arctogadus spp. is poorly described, in part because their taxonomy remains uncertain, with at least two species (A. borisovi, A. glacialis), distinguished in the Atlantic Arctic (Chernova). In both the Atlantic and the Pacific Arctic, A. glacialis overlap with B. saida, but are much less abundant (Madsen et al., Bouchard et al.). For example, only 8-9% of larval cod sampled in the Amundsen Gulf were classified as A. glacialis (Bouchard et al.).

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Figure 2. The Polar cod (Boreogadus saida), also known as Arctic cod, has a circumpolar distribution extending into the marginal seas. Photo credit: Sheiko and Mecklenburg. Map from Mecklenburg & Mecklenburg (http://www.arcodv.orgFish/Boreogadus_saida.html).

There is considerable genetic structure in the population of B. saida at both large (1000s of km) and smaller geographic scales (Nelson et al., Præbel et al.). Analysis of microsatellite DNA suggests that populations in eastern Canada and West Greenland are distinct from those in the Pacific Arctic, with smaller-scale structure separating populations in the Chukchi and US Beaufort Sea from those in the Canadian Beaufort Sea and Amundsen Gulf (Nelson et al.). Population divergence seems to be occurring in some isolated (silled) fjords in East Greenland, while no population structure was evident in shelf populations from East Greenland to Svalbard (Præbel et al.).

Polar cod occupy a wide variety of habitats including nearshore, shallow waters, Arctic and subarctic shelves, continental slope regions and the central Arctic basin. The largest abundances have been observed in the eastern and northern Barents Sea, where they have supported a modest-sized fishery of up to 50,000 t in recent decades (Krivosheya). Biomass estimates in the region peaked at 2 million t in 2006, but have declined to less than 400,000 t in 2013 in spite of relatively conservative exploitation rates from 0 to 4% (Krivosheya). Reductions in abundance may be related to increasing abundances of potential competitors such as capelin or predators such as Gadus spp. (Hop and Gjøsæter). High abundances of B. saida have also been observed along the outer shelf and slope of the Canadian Beaufort Sea and Amundsen Gulf (Majewski et al., Geoffroy et al.), where peak abundances typically occur below cold Pacific waters in a layer of slightly warmer Atlantic water (350-500 m). Young-of-the-year cod occupy the fresher surface layer (Marsh et al, Geoffroy et al.), while larger fish occupy deeper waters, thereby limiting cannibalism. Mean size generally increases with depth, suggesting an ontogenetic movement towards deeper waters (Geoffroy et al.). Polar cod also range into subarctic waters including the Bering Sea and Iceland, where they expand during cool periods such as those associated with extensive ice cover in the Bering Sea (Marsh et al.) and with the intrusion of polar water masses onto the shelf north of Iceland (Astthorsson).

Nearshore aggregations of B. saida are found in the fjord systems of East Greenland (Madsen et al.), Svalbard (Nahrgang et al., Larsen et al.), the Canadian Archipelago (Crawford), and the Beaufort Sea (Divoky & Tremblay). Nearshore distributions are highly dynamic and respond to variability in small-scale oceanographic features such as tidal fronts that can interact with topography to provide shelter from jellyfish predators (Crawford). In nearshore waters of the Beaufort Sea, B. saida are closely associated with sea ice and have become less available to coastal predators such as shallow-diving seabirds during recent years when sea ice has retreated earlier in the season (Divoky and Tremblay).

Recent advances in under-ice sampling have also confirmed that B. saida are ubiquitous under first year ice in the Arctic basin, where they occur in relatively low densities and presumably feed on sea-ice associated amphipods such as Apherusa glacialis (David et al.). Total under-ice biomass of B. saida in the Eurasian Basin was estimated at 38,000 tons (David et al.).

 

Spawning of B. saida occurs primarily in shallow, nearshore areas as inferred from the distribution of larvae. Known spawning concentrations in the Atlantic occur during winter along the east coast of Novaya Zemlya in the Kara Sea, in the southeast Barents Sea, and around Svalbard (Krivosheya, Hop & Gjøsæter). High larval concentrations imply that spawning concentrations in the Pacific Arctic occur in the eastern Chukchi Sea (Marsh et al.) and in the southeast Beaufort Sea (Bouchard et al.).

B. saida and A. glacialis differ in their growth and reproductive characteristics. For example, A. glacialis hatch at a larger size, have a larger size at least through metamorphosis, achieve a larger size overall, have a longer life span, and mature later than B. saida (Bouchard et al.). Under laboratory conditions, B. saida at very low temperatures (0°C) grow much faster than other gadids such as Pacific cod or walleye pollock (Laurel et al.). Optimal growth under unlimited food conditions occurs at ~5°C but decreases rapidly at higher temperatures (Laurel et al, Kunz et al.). Growth rates in the ocean can vary substantially among regions, as evident in a much larger mean size at-age in the Barents Sea compared to the Kara Sea (Raskhozheva). Around Svalbard, Polar cod in both an Arctic-type and a warmer Atlantic-type fjord grew to a very similar size by age-1, but the size-at-age of older fish, as well as their fecundity, was considerably larger in the colder, Arctic fjord (Nahrgang et al.). In the Arctic domain, female Polar cod also grow to a larger size, mature later, and have a longer life expectancy than males (Nahrgang et al.).

The population dynamics of B. saida are poorly understood and only the Barents Sea stock is regularly surveyed. The estimated production to biomass ratio ranges from 0.6 to 1.1 and has increased between 1969-1981 and 1986-2008, associated with a younger age structure (primarily 2-3 year old fish) and earlier maturation in recent decades (Raskhozheva). Abundances have fluctuated widely since the 1960s, which cannot be attributed to fishing alone (Krivosheya). Models to simulate the future dynamics of Polar cod under climate change are currently under development (Duarte et al.).

Polar cod have generally been recognized as a key link between lower trophic levels and higher tophic levels such as seabirds and mammals. Diet composition varies among regions, but diets are typically dominated by calanoid copepods and hyperiid amphipods, in particular Themisto spp. Larval B. saida feed almost exclusively on calanoid copepods or their nauplii in the Beaufort Sea (Bouchard et al.) and in the Chukchi Sea (Marsh et al.). The diet of demersal B. saida in the Beaufort Sea varies with depth and is dominated by Calanus hyperboreus and C. glacialis on the shelf (Majewski). The proportion of T. libellula in the diet, as well as their abundance in the water column, increase with depth and T. libellula dominate on the lower slope. These three prey species, along with T. abyssorum, make up over 90% of B.saida diets in the Canadian Beaufort Sea. Similarly, T. libellula dominates diets in the Kara Sea (Orlova et al.). In contrast, larger (> 60mm) Polar cod in the Chukchi Sea (Marsh et al.) and in the Barents Sea (Orlova et al.) consumed a much larger variety of prey items, including fish (10-20%). The proportion of copepods decreases and the proportion of fish and amphipods typically increases with size (e.g. Orlova et al.). A shift to feeding at higher trophic levels with increasing size is also confirmed by isotopic analyses. Cannibalism has been reported but was relatively rare in the Barents & Kara Sea (< 1.4% frequency of occurrence), although it can account for up to 8% of diets by weight (Orlova et al.). Cluster analyses suggest that diets of B. saida in the Barents Sea overlap most strongly with capelin, while there was very little overlap with the diets of A. glacialis.

Polar cod are believed to be vulnerable to anthropogenic influences with expected effects on their distribution (Marsh et al., Astthorsson), growth (Laurel et al., Nahrgang et al., Hop & Gjøsæter), and fecundity (Nahrgang et al.). Due to their important trophic role in the Arctic marine ecosystem, these effects will likely alter ecosystem structure and functioning in the Arctic and Polar cod in the marginal seas of the Arctic may be replaced by boreal species such as capelin under continued warming (Hop & Gjøsæter). Moreover, Polar cod in the Arctic Ocean may be impacted by ocean acidification resulting from increased levels of atmospheric CO2. Under CO2 levels expected by the end of the century, Polar cod in the laboratory had reduced growth rates and exhibited behavioural changes (Kunz et al., Schmidt et al., Storch et al.). Transcriptomic studies are underway to determine the capacity of Polar cod to adapt to changing temperatures and CO2 levels (Windisch et al.).

The goal of the workshop was to bring together scientists from around the circumpolar Arctic to focus exclusively on the ecology of Arctic Gadids and, by all accounts, it was an unqualified success thanks to the thoughtful contributions of all presenters and other participants. We thank the POLARISATION project (Research Council of Norway), IMBER and the International Arctic Science Committee for providing generous travel support and the Natural History Museum of Denmark, University of Copenhagen, for hosting the workshop.  

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The Atlantic Multidecadal Oscillation and its impacts in the northern North Atlantic and Arctic

Kenneth F. Drinkwater1,5, M. Miles2,5, I. Medhaug3,5, O.H. Otterå2,5, T. Kristiansen1,5, S. Sundby1,5, & Y. Gao4,5

1Institute of Marine Research, Bergen, Norway
2Uni Research, Bergen, Norway
3Geophysical Institute, University of Bergen, Bergen, Norway
4Nansen Environmental and Remote Sensing Center, Bergen, Norway
5Bjerknes Centre for Climate Research, Bergen, Norway

 

Instrument records have documented that sea surface temperatures (SSTs) in the North Atlantic basin have varied on multidecadal time scales over the last 150 years or more, a pattern commonly referred to as the Atlantic Multidecadal Oscillation or AMO following Kerr (2000). Enfield et al. (2001) defined an AMO index as the 10-year running mean of the linear detrended sea surface temperature anomalies (SSTAs) averaged over the North Atlantic Ocean from 70ºN to the equator with positive (negative) values corresponding to warm (cold) conditions. Others used slightly different areas of the North Atlantic to average over or in the detrending, but, the main characteristics of the estimated AMO indices are similar. The principal temporal pattern is one of cooling in the late 1800s and early 1900s, a warm period beginning in the 1920s and extending into the 1960s, a cool period in the 1970s and 1980s and another warm period beginning in the 1990s extending to the present. This suggests a period of approximately 60–80 years (Fig. 3).  Paleoclimatic studies indicate that such multidecadal variability has been a persistent feature in the past (Gray et al., 2004; Kilbourne et al., 2014).

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Figure 3. The unsmoothed Kaplan SST dataset and the 10-year running mean of the Atlantic Multidecadal Oscillation (AMO) for the period 1856–2008 (http://www.cdc.noaa.gov/Timeseries/AMO/).

A number of mechanisms have been proposed in recent years to account for the observed variability in the AMO. One hypothesis suggests that SST variations in the Atlantic are ultimately atmospherically-induced, with random fluctuations in the atmospheric circulation giving rise to a low-frequency SST response through surface energy fluxes, Ekman currents and thermal inertia (Deser et al., 2010). The most commonly accepted view, however, is that the AMO, at least partially, reflects natural internal variations in the strength of the Atlantic Meridional Overturning Circulation (AMOC), with a stronger than normal overturning being associated with warmer North Atlantic temperatures (Polyakov et al., 2010). Häkkinen et al. (2011) highlighted the similarity in the AMO with an index of atmospheric blocking over the North Atlantic, with increased blocking leading to reduced heat loss from the ocean, contributing to the warm phase of the AMO. Others have noted the potential importance of volcanic aerosols (Otterå et al., 2010; Booth et al., 2012). Further studies are required before the predominant mechanism(s) for the AMO can be confirmed.

AMO-like variability in atmospheric and ocean temperatures has been observed not only throughout most of the North Atlantic but also in the Arctic (Fig. 4; Polyakov et al., 2010; Medhaug and Furevik, 2011). These ocean temperature changes have been observed down to at least 500 m in the subarctic region (Drinkwater, 2006). Changes in ocean currents also vary with the AMO. For example, the propagation of Atlantic waters into the Arctic show increased flow during warm periods (Polyakov et al., 2007) while during the cold phase of the AMO there is enhanced outflow of polar waters and sea-ice export from the Arctic through the Fram Strait. Sea-ice extent also varies with the AMO signal as shown in the Atlantic sector of the Arctic (Wood et al., 2010), the Kara Sea (Frankcombe et al., 2010), the Greenland Sea (Miles et al., 2014) and off West Greenland (Lloyd et al., 2011). As expected, reductions in sea ice occur during warm (AMO+) periods and expansion during cold (AMO-) periods.

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Figure 4. The 10-year running mean of the annual detrended sea temperature anomalies from the Barents Sea (Kola Section) and the AMO Index. 

Biological Impacts

The AMO also impacts the biological components of the ecosystem. For example, warm and cold periods have long been linked to variability in recruitment dynamics and growth of fish, particularly for boreal species such as Atlantic cod, Gadus morhua (Ottersen and Loeng, 2000). During the AMO+ phase, there has been increased cod abundance especially in the more northern regions of the North Atlantic. The increased cod productivity has been hypothesized to be driven by increased primary and secondary production (Drinkwater, 2006). During the warm periods, cod also expanded northward, off West Greenland, Iceland and in the Barents Sea and off Norway there was increased spawning to the north (Sundby and Nakken, 2008).

 

Off Norway Atlantic herring (Clupea harengus) is another species that has shown strong multidecadal variability linked to the ocean temperatures that exhibit AMO-variability (Fig. 5; Toresen and Østvedt, 2000). During AMO+ there is an increase in abundance of Norwegian spring-spawning herring and an expansion westward in their feeding migrations. During the mid-20th century, they reached Iceland, resulting in the opening of the herring fisheries, an industry that came to dominate the Iceland economy for 3–4 decades.  The herring abundance began to decline oweing to intense fishing pressure and, shortly thereafter, worsening environmental conditions. The declining abundance levels caused the herring to retreat eastward and for several years they were found year-round near the west coast of Norway, where they continued to spawn. A fishing moratorium that lasted for over 20 years was imposed by Norwegian fisheries management. Eventually, the stock abundance increased concurrent with the rise in sea temperatures (Fig. 3; Toresen and Østvedt, 2000).  With the recent increase in abundance, the adult herring have again expanded their territory westward, some as far as Iceland, in a similar manner to what transpired in the previous warm period (Drinkwater, 2009). 

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Figure 5. Smoothed spawning stock biomass (SSB) of Norwegian spring spawning herring and sea temperatures from the Kola Section in the Barents Sea.

Other species have also shown responses to the warm and cold periods although the datasets are generally not long enough or complete enough to show statistical relations with the AMO. For example, during the mid-20th century warming Atlantic salmon (Salmo salar) and haddock (Melanogrammus aeglefinus) increased in abundance and/or expanded northward off West Greenland, while capelin (Mallotus villosus) retreated northward. At the same time, beluga whales (Delphinapterus leucas) and narwhals (Monodon monoceros) arrived earlier off Greenland and left later on their annual migrations. Species that tended to inhabit warmer waters to the south became occasional visitors off Greenland, Iceland and Norway and sometimes took up temporary residency during the mid-20th century warming (Drinkwater, 2006).  As the temperatures declined in the 1970s, these species shifted their distributions southward and the migration timing returned to previous patterns, while in the present warming period there have again been increasing reports of the invasion of warm water species into the region (Astthorsson and Palsson, 2006). 

It is not only fish that are affected by the multidecadal variability. Although long-term plankton datasets are rare, shorter data records have suggested that there was increased phytoplankton and zooplankton during the ETCW (Drinkwater, 2006). With the advent of cooler temperatures, plankton populations declined in response to a decrease in incoming solar radiation caused by increased cloudiness (Cushing and Dickson, 1976).  As a result, at this time there was a delay in the order of one month in the phytoplankton bloom, e.g., in the southern Norwegian Sea (Robinson, 1969).  A decline in zooplankton abundance also occurred during this cold period in the Northeast Atlantic between the North Sea, the Norwegian Sea and Iceland (Colebrook, 1978). Plankton trends in more northern areas of the North Atlantic or the Arctic at this time are not available due to lack of data. With the rise in temperatures in the 1990s, phytoplankton production in the Barents Sea has increased (Mueter et al., 2007).  Based on satellite data, this is believed to be related to increased light levels and a longer production period caused by the reduction in seasonal sea-ice coverage.

Benthic fauna and flora have also been affected by multidecadal variability in their environment.  Blacker (1957) showed that during the ETCW, in contrast to earlier years, the benthos associated with Atlantic waters spread over 500 km northward along West Spitsbergen as a result of changes in the circulation patterns that increased the influence of Atlantic Waters in the region (see section 3.1). At the same time within the Barents Sea, the Atlantic benthos spread farther eastward off the Murman Peninsula in Russia with the increasing influence of the Atlantic inflow (Nesis, 1960).

For further details on the AMO and its biological impacts in the northern North Atlantic see Drinkwater et al. (2014) and on the AMO in general see the special issue edited by Alheit et al. (2014).

     

References

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  • Robinson, G.A. 1969. Fluctuations in the timing of the spring outbreak of phytoplankton in the north-east Atlantic and the North Sea. ICES CM 1969 Doc. L:16.
  • Sundby, S. & Nakken, O. 2008. Spatial shifts in spawning habitats of Arcto-Norwegian cod related to multidecadal climate oscillations and climate change. ICES Journal of Marine Science 65: 953–962.
  • Sutton, R.T. & Hodson, D.L.R. 2005. Atlantic Ocean forcing of North American and European summer climate. Science 309: 115–118.
  • Toresen, R. & Østvedt, L.J. 2000. Variation in abundance of Norwegian spring-spawning herring (Clupea harengus, Clupeidae) throughout the 20th century and the influence of climatic fluctuations. Fish and Fisheries 1: 231–256.
  • Wood, K.R., Overland, J.E., Jonsson, T. & Smoliak, B.V. 2010. Air temperature variations on the Atlantic-Arctic boundary since 1802. Geophysical Research Letters 37, L17708, doi:10.1029/2010GL044176.
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Catastrophic reduction of sea-ice in the Arctic Ocean – its impact on the marine ecosystems in the polar region

Naomi Harada1, Katsunori Kimoto1, Jonaotaro Onodera1, Eiji Watanabe1, Makio C. Honda1, Michio J. Kishi2, Takashi Kikuchi1, Yuichiro Tanaka3, Manami Satoh4, Fumihiro Itoh4, Yoshihiro Shiraiwa4, Kohei Matsuno5, Atsushi Yamaguchi2

1Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan,
2Hokkaido University, Sapporo, Japan
3National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan 
4University of Tsukuba, Tsukuba, Japan
5National Polar Research Institute, Tachikawa, Japan

 

Catastrophic reduction of sea-ice in the Arctic Ocean – its impact on the marine ecosystems in the polar region is an ESSAS endorsed project, funded by the Japan Society for the Promotion of Science from 2010 to 2014. Sea-ice in the Arctic Ocean has been dramatically reduced over the past decade. This reduction causes complex and enigmatic changes in the marine ecosystem throughout the Arctic Ocean, because of the simultaneously occurrence of “disadvantageous” phenomena, such as ocean acidification (Yamamoto-Kawai et al., 2009) and “advantageous” phenomena such as improved light conditions for marine organisms (Nishino et al., 2009). The project focused on the western Arctic Ocean where there has been the most serious sea-ice reduction in the Arctic region (Fig. 6). The aims of the project were to 1) understand the temporal changes in primary production and the biological pump, 2) understand the physiological response of marine phyto- and zooplankton to ocean acidification that is occurring simultaneously with warming and freshening from the sea-ice melting, and 3) develop a model to simulate the primary production, and understand the response of marine ecosystems and the biological pump to the environmental changes caused by rapid sea-ice reduction in the Arctic Ocean.

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Figure 6. Map of the study site, Northwind Abyssal Plain in the western Arctic Ocean.

Three methods have been used: observations from research vessels and satellites; experimental culture and breeding of plankton; and marine ecosystem modelling. The specific research outlines are as follows:

  • stimation of changes in sea-ice thickness and areal extent, and water mass structure to understand annual changes in the physical oceanographic environment associated with sea-ice expansion or reduction in the Arctic Ocean;
  • Detection of seasonal and annual changes in primary production biomass and its composition using the time-series data from a sediment trap mooring system;
  • Understanding changes in the physiological response of coccolithophores and foraminifera to environmental changes caused by sea-ice melting from culture/breeding experiments; and
  • Development of new models for Arctic Ocean ecosystems based on the NEMURO model (developed to describe marine ecosystems, including fish resources, in the subarctic North Pacific) to reproduce the primary and secondary production of the region, and predict the distribution of possible fish resources.
 

New results have been obtained from the observations, culture experiments and ecosystem models. Seasonal variations in the biogenic component fluxes of the Northwind Abyssal Plain, recorded from year-round time-series data from the sediment trap system at St. NAP, 75°N, 162°W from October 2010 to September 2011, have been clarified. Total mass fluxes and organic material fluxes showed distinct seasonal changes, being higher in summer (July to September) and at the beginning of the polar night season (November to December). Diatoms were the most dominant component. For the mesozooplankton community, the zooplankton swimmer flux was greatest from July to October and was dominated by copepods. Pacific copepods (Neocalanus cristatus) were present in significant numbers from August to September (Matsuno et al., 2013). Eddies appear to be an important physical mechanism driving the change in biogenic fluxes associated with the seasonal sea-ice extent. The recent increase in eddy occurrence might have contributed to the increased biogenic fluxes in the study area (Watanabe et al., 2014).

The quantitative evaluation of pteropod shell dissolution as a result of ocean acidification, was undertaken using Micro-focus X-ray Computing Tomography (MXCT). MXCT evaluates shell density and inner structure very precisely. Evidence of the dissolution of the shells of calcifying zooplankton was obtained from the time-series sediment trap observations. At Stn. NAP in the Arctic Ocean, pteropods with aragonite shells were severely damaged in November, 2010 (Fig. 7). The results indicate that marine calcifers are affected by acidification in the western Arctic Ocean and that the biological responses to ocean acidification vary between species and seasons.

Further results from this project will be published in the scientific literature in the coming months and over the next few years.

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Figure 7. The cross section of shell density of pteropods derived from the time-series sediment trap experiment at 180 m depth in the Northwind Abyssal Plain (left image: October 2010; right image: November 2010). Red and blue indicate high and low shell density, respectively.

     

References

  • Matsuno K., Yamaguchi A., Fujiwara A., Onodera J., Watanabe E., Imai I., Chiba S., Harada, N. & Kikuchi T. 2013. Seasonal changes in mesozooplankton swimmers collected by sediment trap moored at a single station on the Northwind Abyssal Plain in the western Arctic Ocean. J. Plankton Res. doi:10.1093/plankt/fbt092.
  • Nishino S., Shimada K., Itoh M. & Chiba S. 2009. Vertical double silicate maxima in the sea-ice reduction region of the western Arctic Ocean: implications for an enhanced biological pump due to sea-ice reduction. Journal of Oceanography 65: 871-883.
  • Yamamoto-Kawai M., McLaughlin F.A. Carmack E.C, Nishino S. & Shimada K. 2009. Aragonite undersaturation in the Arctic Ocean: effects of ocean acidification and sea ice melt, Science 326: 1098-1100.
  • Watanabe E., Onodera J., Harada N., Honda M.C, Kikuchi T., Nishino S., Matsuno K., Yamaguchi A., Ishida A., & Kishi M.J. In press. Enhanced role of eddies in the Arctic marine biological pump. Nature Communication.
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A comparison of Calanus finmarchicus population dynamics and environmental conditions in the Labrador and Norwegian seas

E. J.H. Head1, W. Melle2, P. Pepin3, E. Bagøien2 and C. Broms2

1Fisheries and Oceans Canada, Bedford Institute of Oceanography, P.O. Box 1006, NS, Canada B2Y 4A2
2Institute of Marine Research, P.O. Box 1870, Nordnes, N-5817, Norway
3Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre, P.O. Box 5667, St John’s, NL Canada A1C 5X1

 

The copepod Calanus finmarchicus dominates the biomass of the mesozooplankton throughout the North Atlantic from Cape Hatteras (<40oN) in the southwest to the Barents Sea (>80oN) in the northeast. The species has an annual life history cycle over much of its range, with pre-adults (stage CVs) spending the winter dormant at depth, waking up in advance of the spring bloom in late winter or early spring, and maturing and mating as they return to the surface. Egg-laying takes place mainly during the bloom, and the offspring develop during and after the bloom, descending to depth as CVs in summer or autumn. The actual timing of these life history events (phenology), however, varies regionally in response to differences in environmental conditions.

The different life history stages of C. finmarchicus serve as important, sometimes critical, food sources for larval, juvenile and adult fish, including commercially important species such as cod, haddock, herring and mackerel, and also for some baleen whales and seabirds. Under climate change, as the North Atlantic warms, we expect that there will be changes in phytoplankton bloom dynamics and that in turn these changes in temperature and food availability will influence the phenology and distribution of C. finmarchicus. In order to anticipate these changes, and their likely effects on higher trophic levels, we need to have a good understanding of the relationship between C. finmarchicus life history and productivity and the environment.

There are two regions in the North Atlantic which, because of their depth and the retentive nature of their circulation, serve as major overwintering areas and distribution centres for C. finmarchicus. One is the sub-polar gyre located in the Northwest Atlantic and the other is the gyre that encompasses the Nordic seas in the Northeast Atlantic. The Labrador Sea comprises the western portion of the sub-polar gyre, while the Norwegian Sea is located in the eastern region of the Nordic sea gyre. The Labrador Sea and Norwegian Sea present contrasting environments, since they differ in latitude, and hence day length, and in the relative contributions of warm water from the south versus cold water from the north (Fig. 8). In this study, we used a comparative approach to investigate differences among C. finmarchicus populations in relation to environmental conditions for various regions within the Labrador and Norwegian seas, with a view to understanding potential impacts of future climate change.

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Figure 8. Circulation patterns in the North Atlantic basin from Sundby et al. (1980). Arrows with full lines represent Atlantic Water, broken lines, Arctic Water, and dotted lines, Coastal Water. 

Contrasting environmental conditions and Calanus finmarchicus demography in the Labrador and Norwegian seas

The Norwegian Sea is generally warmer than the Labrador Sea, especially in winter and at the time of the spring bloom, which generally starts in April or May throughout both regions. Sea surface temperatures vary among different areas of each sea, and from year-to-year, and spring blooms tend to occur earlier in warmer areas and warmer years.

C. finmarchicus populations show differences in physical characteristics (female size), physiological rates (egg production rates) and seasonal cycles of abundance between the Labrador and Norwegian seas. Female C. finmarchicus from the Labrador Sea are larger than those from the Norwegian Sea and their egg production rates are higher for a given in situ chlorophyll (food) concentration with maximum values of 62 and 34 eggs female-1 d-1 at chlorophyll concentrations higher than 4.5 mg m-3 for the Labrador and Norwegian seas, respectively (Fig. 9).  Egg production rates show no obvious relationship with temperature (Fig. 10), and this is true even when the effect of chlorophyll concentration is accounted for (Head et al. 2013a, Melle et al. in press). Temperature and bloom timing both influence the seasonal cycle of C. finmarchicus reproduction and development. Thus, for example, the seasonal production cycle occurs earlier in the year in the Norwegian Sea, where the bloom starts in early May at a temperature of ~8oC, than in the eastern Labrador Sea, where the bloom starts earlier, in late April, but at a temperature of ~2oC (Fig. 11B, C). Reproduction ceases as the bloom dies out and most CVs leave the surface layers by late July in the Norwegian Sea, but not until after July in the eastern Labrador Sea (Fig. 11B, C).

 
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Figure 9. Egg production rates of Calanus finmarchicus females in relation to integrated chlorophyll concentration (0-30 m) in the Labrador and Norwegian seas. The curve fitted to the Labrador Sea data is given by the expression EPR = 62.42(1-e-0.026Chl), the one for the Norwegian Sea data is given by the expression EPR = 34.60(1-e-0.018Chl). 

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Figure 10. Egg production rates of Calanus finmarchicus females in relation to temperature (at 5 m depth) in the Labrador and Norwegian seas. 

Concentrations of overwintering stage CVs in the Norwegian Sea and the eastern Labrador Sea are not very different, implying that in these regions net productivity of C. finmarchicus is similar despite differences in environmental conditions (lower phytoplankton concentrations and higher temperatures in the Norwegian Sea). In central and western areas of the Labrador Sea overwintering CVs are less abundant by a factor of two, apparently due to high local mortality rates for eggs and nauplii (Fig. 11A).

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Figure 11. Abundance of Calanus finmarchicus by stage in (A) the Central Labrador Sea (0-100 m), (B) the eastern Labrador Sea (0-100 m) and (C) the Norwegian Sea (0-200 m, Atlantic Waters, Svinøy section) together with integrated chlorophyll concentrations (0-30 m) and near-surface temperatures (5 m). 

Effects of climate warming on C. finmarchicus

With global warming, as temperatures increase in the Norwegian and Labrador Seas, our observations suggest that the timing of life history events for C. finmarchicus will be advanced and the number of generations produced per year could increase. The time spent in the near surface layers will probably decrease, but overall, for modest temperature increases, the effect on population size may not be large. On the other hand, further south in the North Sea C. finmarchicus abundance has diminished markedly over recent decades, and this has also occurred more recently in the southern Norwegian Sea (Dalpadado et al. 2012). The degree to which these changes result from changes in circulation versus increasing temperatures is unclear, although they clearly demonstrate that some C. finmarchicus populations are vulnerable to changes in environmental conditions, which will undoubtedly have important consequences for dependent species in ffected regions.

Further details on this study and its results can be found in Head et al. (2013b).

     

References

  • Head, E.J.H., Harris, L.R., Ringuette, M., and Campbell, R.W. 2013a. Characteristics of egg production of the planktonic copepod, Calanus finmarchicus, in the Labrador Sea: 1997-2010. Journal of Plankton Research 35: 281-298.
  • Head, E.J.H., Melle, W., Pepin, P., Bagøien, E., & Broms, C. 2013b. On the ecology of Calanus finmarchicus in the Subarctic North Atlantic: A comparison of population dynamics and environmental conditions in areas of the Labrador Sea-Labrador/Newfoundland Shelf and Norwegian Sea Atlantic and coastal waters. Progress in Oceanography 114: 46-63.
  • Dalpadado, P., Ingvaldsen, R. B., Stige, L. C., Bogstad, B., Knutsen, T., Ottersen, G., & Ellertsen, B. 2012. Climate effects on Barents Sea ecosystem dynamics.  ICES Journal of Marine Science 69: 1303–1316.
  • Melle, W., Runge, J.A., Head, E., Plourde, S., Castellani, C., Licandro, P., Pierson, J., Jonasdottir, S.H., Johnson, C., Chust, G., Broms, C., Debes, H., Falkenhaug, T., Gaard, E., Gislason, A., Heath., M.R., Niehoff, B., Nielsen, T.G., Pepin, P., & Stenevik, E.K. In press. The North Atlantic Ocean as habitat for Calanus finmarchicus: environmental factors and life history traits. Progress in Oceanography
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Recent decline of northern shrimp stocks in the Northwest Atlantic – Coincidence, multiple causes or response to synchronous changes in the environment?

Kai Wieland1*, Helle Siegstad2, José Miguel Casas Sanchez3 and David Orr4

1 Technical University of Denmark, Institute of Aquatic Resources (DTU Aqua), Hirtshals, Denmark; * corresponding author, e-mail:  kw@aqua.dtu.dk,
2 Greenland Institute of Natural Resources (GINR), Nuuk, Greenland
3 Instituto Espanol de Oceanografia (IEO), Centro Oceanografio, Vigo, Spain
4 Fisheries and Oceans Canada (DFO), Northwest Atlantic Fisheries Centre, St John’s, Canada

 

After a period of record high catches, stock size of almost all Northwest Atlantic populations of northern shrimp (Pandalus borealis) has declined. This has been accompanied by a warmer ocean climate and, in some areas, an increase in major predator abundance, resulting in growing concern in coastal states about the fishing possibilities of this valuable resource in the near future.

Northern shrimp populations in the Northwest Atlantic, considered in detail by the NAFO/ICES Pandalus Assessment Group (NIPAG), are located in East and West Greenland waters, at the Flemish Cap (NAFO division 3M) and on the Grand Banks off Newfoundland (NAFO divisions 3LNO)(Fig. 12).

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Figure 12. Statistical areas used for stock assessments in the Northwest Atlantic by NAFO (Yellow lines: EEZ boundaries (www.nafo.int).  

Oceanographic conditions in the Northwest Atlantic are closely linked to ocean current circulation (Fig. 13), and in turn, climate-driven changes to circulation patterns are major drivers of ecosystem variability. A general warming of the North Atlantic has been observed in recent years and it is most intensive in the northern regions (Holliday et al. 2011a). Sea surface temperature (SST) of the North Atlantic has shown a decadal variability, known as the Atlantic Multidecadal Oscillation (AMO), which is linked to large-scale oceanic circulation. Predictions suggest that coming decades may experience a cooling of the surface waters as the AMO index moves into a downward trend from its current high (Holiday et al. 2011b). It is expected that such changes will have a major effect on fish abundance, through their influence on recruitment related to the match/mismatch of the timing of larval hatch relative to the production of food, and the connectivity between spawning and nursery areas (Kulka et al. 2011).

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Figure 13. Major pathways associated with the transformation of warm subtropical waters (red to yellow) into cooler subpolar and polar waters (blue to green) in the Northwest Atlantic (Illustration by James Cook, Woods Hole Oceanographic Institution, www.whoi.edu/oceanus).

Total catch of northern shrimp in East and West Greenland, the Flemish Cap and on the Grand Banks decreased from 210 kt in 2003 to about 130 kt in 2012. Recent advice recommends a further decline of total allowable catch to about 100 kt in 2013, of which 80 kt are allocated to West Greenland waters and the remaining 20 kt to East Greenland and the Grand Banks. The moratorium for shrimp fishing introduced in 2011 at the Flemish Cap should continue (NAFO 2012).

 

Indices of northern shrimp stock size declined in all areas considered in this study in recent years. (Fig. 14). This was most pronounced for the Flemish Cap where northern shrimp almost dissappeared. In West Greenland, estimates of survey biomass decreased drastically and northern shrimp disappeared from the southern areas, as the commercial catch per unit effort (CPUE) remained at a relatively high level. The difference between survey estimates and commercial CPUE was due to the fact that the fishery concentrated on the more northern offshore area (NAFO Div. 1B) (Hammeken Arboe 2012). However, catch rates there have also declined considerably in  recent years, and high densities of northern shrimp have moved towards shallower waters where the bottom temperature is lower. There is no identication that the stock has extended its distribution towards the north into Baffin Bay (Kingsley et al. 2012). Average near-bottom temperatures were fairly similar in the four regions. Surface layer temperatures differed, however, with the highest values encountered at the Flemish Cap and the lowest on the Grand Banks (Fig. 14, Holliday et al. 2011a), due to the influence of the warm Gulf Stream water and cool Labrador current, respectively.

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Figure 14.  Catches of northern shrimp at East (EGL) and West (WGL) Greenland, the Flemish Cap (FC) and on the Grand Bank (GB) om 2003 to 2012. 

  

In general, the warmer conditions in the Northwest Atlantic are associated with high biomass of Atlantic cod, which in turn has a negative impact on northern shrimp stocks through predation (Worm & Myers 2003, Drinkwater 2009). Survey estimates of Atlantic cod biomass have substantially increased in the study areas over the past decade, in particular off East Greenland and at the Flemish Cap. In West Greenland, the increase in Atlantic cod biomass was initially limited to the southernmost area, but in the last two years its distribution has extended northwards into NAFO Div. 1B, resulting in the widest spatial overlap with the offshore component of the northern shrimp stock since the late 1980s (Retzel 2012). Thus, the effective biomass of both main predators, Atlantic cod and Greenland halibut (Wieland & Siegstad 2012), have considerably increased in this region.

After a period in which there were rich year-classes, recruitment of northern shrimp has been poor in recent years. Consequently, the fishable biomass is expected to decrease further in the next few years, and it is unlikely that this will reverse in the near future if the current environmental conditions persist.

The duration of demersal summer-to-spring egg-bearing period of northern shrimp stocks is timed to the spring phytoplankton bloom in the long-term average (Koeller et al. 2009) and colder bottom waters appear to be more favourable than warmer ones (Greene et al. 2009, Richards et al. 2012). However, has been difficult to prove a direct link between northern shrimp recruitment and the characteristics of the phytoplankton spring bloom in general (Quellet et al. 2011). At least in some areas, the impact of predation, not only by Atlantic cod but also by other predators such as Greenland halibut (Wieland & Siegstad 2012) may be more important. In addition, the effect of climate change and its link to oceanic circulation on the connectivity between spawning and nursery areas is poorly understood for northern shrimp. However, in contrast to fish species such as Atlantic cod and herring that are able to undertake extended spawning migrations, it appears unlikely that northern shrimp can simply extend their distribution northwards into areas with more appropriate temperature conditions.  However, an interdisciplinary research project covering a variety of northern shrimp stocks may help to answer these questions.

Acknowledgements 

Temperature data for the Flemish Cap were provided by E. Colbourne (Fisheries and Oceans, St John’s, Canada).

     

References

  • Drinkwater, K. 2009. Comparison of the response of Atlantic cod (Gadus morhua) in the high-latitude regions of the North Atlantic during the warm periods of the 1920s-1960s and the 1990s-2000s. Deep Sea Research II 56: 2087-2096.
  • Greene, C.H., Monger, B.C. & McGarry, P. 2009. Some like it cold. Science 224: 733-734.
  • Hammeken Arboe, N. 2012. The fishery for northern shrimp (Pandalus borealis) off West Greenland, 1970-2012. NAFO SCR Doc. 12/048.
  • Holliday, N.P., Quante, M., Sherwin, T., Nolan, G., Mork, K.-A., Cannaby, H., & Berry, D. 2011. North Atlantic circulation and atmospheric forcing. In: Reid, P.C. and Valdés, L. (eds.) ICES status report on climate change in the North Atlantic. ICES Cooperative Research Report 310: 8-20.
  • Holliday, N.P., Hughes, S.L., Borenãs, K., Feistel, R., Gaillard, F., Lavin, A., Loeng, H., Mork, K.-A., Nolan, G., Quante, M., & Somavilla, R. 2011. Long-term variability in the North Atlantic Ocean. In: Reid, P.C. and Valdés, L. (eds.) ICES status report on climate change in the North Atlantic. ICES Cooperative Research Report 310: 21-46.
  • Kingsley, M.C.S., Siegstad, H. & Wieland, K. 2012. The West Greenland trawl survey for Pandalus borealis, 2012, with reference to earlier results. NAFO SCR Doc. 12/044.
  • Koeller, P., Fuentes-Yaco, C., Platt, T., Sathyendranath, S., Richards, A., Ouellet, P., Orr, D., Skúladóttir, U., Wieland, K., Savard, L., & Aschan, M. 2009. Basin-scale coherence in phenology of shrimps and phytoplankton in the North Atlantic. Science 224: 791-793.
  • Kulka, D.W., Simpson, S.D., van Hal, R., Duplisea, D., Sell, A., Teal, L., Planque, B., Otterson, G., & Peck, M. Effects of climate variability and change on fish. In: Reid, P.C. and Valdés, L. (eds.) 2011. ICES status report on climate change in the North Atlantic. ICES Cooperative Research Report 310: 147-173.
  • NAFO. 2012. NAFO/ICES Pandalus Assessment Group Meeting, 17 – 24 October 2012. NAFO SCS Doc. 12/23.
  • Ouellet P., Fuentes-Yaco, C., Savard, L., Platt, T., Sathyendranath, S., Koeller, P., Orr, D., & Siegstad, H. 2011. Ocean surface characteristics influence recruitment variability of populations of northern shrimp (Pandalus borealis) in the North Atlantic. ICES Journal of Marine Science 68, 737-744.
  • Retzel, A. 2012. A preliminary estimate of Atlantic cod (Gadus morhua) biomass in West Greenland offshore waters (NAFO Subarea 1) for 2012 and recent changes in the spatial overlap with northern shrimp (Pandalus borealis). NAFO SCR Doc. 12/057.
  • Richards, R.A., Fogarty, M.J., Mountain, D.G., & Taylor, M.H. 2012. Climate change and northern shrimp recruitment variability in the Gulf of Maine. Marine Ecology Progress Series 464: 167-178.
  • Wieland, K. & Siegstad, H. 2012. Environmental factors affecting recruitment of northern shrimp Pandalus borealis in West Greenland waters. Marine Ecology Progress Series 469: 297-306.
  • Worm, B.A. & Myers, R.A. 2003. Meta-analysis of cod-shrimp interactions reveals top-down control in oceanic food webs. Ecology 84: 162-173.
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Zooplankton composition and trophic relations on feeding grounds of capelin in the Iceland Sea

Olafur S. Astthorsson*, Astthor Gislason, Hildur Petursdottir

Marine Research Institute, Reykjavik, Iceland

 

Capelin (Mallotus villosus) is a key species in the Icelandic marine ecosystem as it is both an important prey for fish, mammals and seabirds, and it supports an extensive fishery. Capelin spawn off the south coast of Iceland and the larvae drift clockwise with the currents to nursery grounds north and east of Iceland, and in some years into the Denmark Strait. Juvenile capelin tend to stay on the outer part of the northern shelf. When they are between 2-4 years old and are maturing, they undertake extensive feeding migrations into the Iceland Sea in early summer, returning to the shelf areas in late summer and fall (Fig. 15). As a result of these migrations, capelin transfer large quantities of the zooplankton production in the Iceland Sea into the Icelandic shelf ecosystem (Vilhjalmsson 2002). 

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Figure 15.  Surface currents around Iceland. From Vilhjalmsson (2002). 

Since the turn of the century, considerable changes have taken place in the marine ecosystem around Iceland and nearby waters (Astthorsson et al. 2007). These changes relate particularly to the increased inflow of warm Atlantic water and the consequent increase in temperature and salinity. It has been suggested that these changes have caused extensive shifts in larval drift and nursery areas of young capelin, feeding and spawning migration of mature capelin, and reduction in stock size. The combined results have also caused difficulties in acoustic assessing of the capelin stock and thus delivery of recommendations for allowable catch. Finally, these changes in distribution have also reduced the accessibility of the capelin for the fishery.

In 2006 the Marine Research Institute in Iceland initiated the Iceland Sea Ecosystem Project (ISEP) with the aim of analysing the ecosystem structure and functioning in the Iceland Sea and adjacent waters (Fig. 15), with particular focus on capelin life history (Palsson et al. 2012). Since its inception, ISEP has been one of the national projects within the ESSAS (Ecosystem Studies of Sub-Arctic Seas) programme.

Data sampling for ISEP involved extensive field work of environmental parameters (temperature, salinity, nutrients), as well as the main trophic components of the system (phytoplankton, zooplankton, fish larvae, pelagic fish) during 2006-2008. Historic data were also analysed with regard to the main objectives of the project. Some of the main findings relating to the zooplankton community in the Iceland Sea and its trophic position are summarized below.

The zooplankton community in the Iceland Sea shows marked differences in abundance and composition, both seasonally in specific years, and between different years (Gislason and Silva 2012). Zooplankton were confined mostly to deeper layers (~200-1000 m) during the winter when temperatures were ~0°C, and had ascended to the surface layers (~0-100 m) by May. They remained there until August, when they returned to the deeper layers. Mesozooplankton diversity in late summer (July/August) was highly variable, but tended to be highest near the shelf edges east of Greenland and north of Iceland, and lowest in the central Iceland Sea. On average copepods made up >90% of the mesozooplankton. Among these, six species (Oithona spp. (~36%), Calanus finmarchicus (~18%), Pseudocalanus spp. (~16%), Oncaea spp. (~12%), Metrida longa (~7%) and C. hyperboreus (~4%)) made up ~92% of copepod numbers. In terms of biomass, three species (C. hyperboreus (~45%), C. finmarchicus (~28%) and M. longa (~17%)) made up ~90%. Two macrozooplankton species (Themiso abysorum, Thysanoessa longicaudata) made up >80% of total macrozooplankton numbers (Fig. 16).

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Figure 16. Distribution of amphipods (upper panels) and euphausiids (lower panels) in the Iceland Sea during August 2007 and 2008 (0-100 m). The samples were collected with Tucker trawls. Thysanoessa spp. are mainly larval stages that could not be identified beyond the genus level. The 500 m bottom contour is shown. Modified from Gislason & Silva (2012). 

 

The relationship between the mesozooplankton community and environmental parameters in late summer were investigated using redundancy analysis (RDA) (Gislason and Silva 2012). In total, 29% of mesozooplankton variability was explained by five variables (salinity, year 2008, bottom depth, temperature and Chl a). Three main zooplankton communities were identified; 1) an Atlantic community in the eastern region where C. finmarchicus, Pseudocalanus spp., Chaetognaths and foraminiferans were most abundant, 2) an Arctic community at relatively high latitude and longitude with large numbers of C. hyperboreus, C. glacialis, Microcalanus spp. and Oncaea spp., and 3) a community with coastal affinities at lower latitudes, with relatively high numbers of e.g. Temoralongicornis, Acartia spp., Podon leuckarti and larvae of benthic animals. The RDA analysis showed that the distribution of macrozooplankton was related to Chl a and salinity. The zooplankton community in the Iceland Sea was generally characterized by a mixture of Arctic and Atlantic species, suggesting that this is a meeting area of these species, with the copepods C. finmarchicus and C. hyperboreus, the amphipod T. abyssorum and the euphausiid T.longicaudata being the most important zooplankton species.

Carbon and nitrogen stable isotopes and fatty acid biomarkers were used to study the trophic linkages and ecology of the most important pelagic species in this ecosystem, focusing particularly on capelin (Petursdottir et al. 2012). According to 15N enrichment the pelagic ecosystem of the Iceland Sea comprises 3-4 trophic levels, excluding birds and mammals. Of the animal species studied, the copepods C. finmarchicus, C. hyperboreus and M. longa, the euphausiid Meganyctiphanes norvegica and the amphipod Gammaruswilkitzkii occupied the lowest trophic level (2.4-2.6), and adult capelin and blue whiting (Micromesistius poutassou) the highest (3.6) (Fig. 17).

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Figure 17.  Trophic relationships in the Iceland Sea in August 2007 and 2008. Stable isotopes of carbon and nitrogen (δ13C og δ15N) for all the species in late summer. Stable nitrogen data for the primarily herbivorous copepod C. hyperboreus, sampled in spring, represented the baseline for trophic level 2. Values are means and TL indicates trophic levels. Denomination: Cf: C. finmarchicus; Ch: C. hyperboreus; Ml: M. longa; Pg: P. glacialis; Ti: T. inermis; Tlo: T. longicaudata; Mn: M. norvegica; Tl: T. libellula; Ta: T. abyssorum; Gw: G. wilkitzkii; Eh: E. hamata; Gm: G. morhua; Ma: M. aeglefinus; Mv: M. villosus, Mv_juv: larvae and juvenile, Mv_10: 10 cm, Mv_16: 16 cm, Mv_ad: adult (11-16 cm); Mp: M. poutassou; Am: A. marinus. Modified from Petursdottir et al. (2012). 

In accordance with their dominance in the plankton community, Calanus spp. proved to be an important dietary component of most of the studied species. Exceptions were the euphausiids, Thysanoessa inermis and T. longicaudata, where Calanus spp. were of minor importance in their diet. The chaetognath, Eukrohnia hamata, was virtually completely carnivorous, feeding almost exclusively on Calanus spp., while most of the other zooplankton species were omnivorous. Young euphausiids were an important food component for capelin larvae, while the amphipod, Themisto libellula, was prominent in the diet of adult capelin. This shift in dietary preference to the westerly distributed Arctic T. libellula by adult capelin may reflect the shift of feeding grounds into Greenland waters where T. libellula was the most abundant amphipod (Fig. 16). The importance of a Calanus-comprised diet increased with the size of capelin. Adult capelin and blue whiting share the same feeding habits. If blue whiting abundance increases with higher temperatures north of Iceland, it could possibly lead to competition for food between the two fish species.

The investigations discussed above where undertaken during times of strong Atlantic inflow (warm years) onto the shelf north of Iceland, somewhat unusual distribution and low stock in terms of biomass of capelin. Long term investigations in Icelandic waters have shown that variations in the inflow of warm Atlantic water onto the northern shelf area have a marked effect on the whole ecosystem. It will therefore, be interesting to monitor the development of the zooplankton community and trophic relations, to obtain comparative data for years of limited inflow of Atlantic water (cold years), with a large capelin stock confined to the Iceland Sea proper.

     

References

  • Astthorsson O. S., Gislason A. & Jonsson S. 2007. Climate variability and the Icelandic marine ecosystem. Deep Sea Research II 54: 2453-2477.
  • Gislason A. & Silva T. 2012. Abundance, composition, and development of zooplankton in the Subarctic Iceland Sea in 2006, 2007, and 2008. ICES J. Mar. Sci. 69: 1263-1276.
  • Palsson et al. Surveys and data collection in the Iceland Sea Ecosystem Project 2006-2008. Hafrannsóknir 164, 5-13 (2012) (In Icelandic, English summary). 
  • Petursdottir H., Falk-Petersen S. & Gislason A. 2012. Trophic interactions of meso- and macrozooplankton and fish in the Iceland Sea as evaluated by fatty acid and stable isotope analysis. ICES J. Mar. Sci. 69: 1277-1288.
  • Vilhjalmsson, H. 2002. Capelin (Mallotus villosus) in the Iceland-East Greenland-Jan Mayen ecosystem. ICES J. Mar. Sci. 59, 870-883.
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Paleoecology of Subarctic Seas

Ben Fitzhugh1, Naomi Harada2, Mike Etnier3, Nicole Misarti4, Arkady Savinetski5, Kana Nagashima2, George Hambrecht6, Anne deVernal7, Dagomar Degroot8, Olga Krylovitch5, and Lester Lembke-Jene9

1University of Washington, Seattle, Washington, USA

2Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan

3Western Washington University, Bellingham, Washington, USA

4University of Alaska Fairbanks, Alaska, USA

5Severtsov Institute of Ecology and Evolution, Moscow, Russia

6University of Maryland, College Park, Maryland, USA

7University of Quebec at Montreal, Montreal, Canada

8York University, Toronto, Canada

9Alfred Wegener Institute, Bremerhaven, Germany

The Working Group on Paleo-Ecology of Sub-Arctic Seas (WGPESAS) convened a session at the ESSAS Annual Science Meeting in Copenhagen in April 2014 to bring a paleo-ecological dimension to the portfolio of ESSAS science, and to explore the engagement of humans in the evolving subarctic ecosystems. The group includes paleo-oceanographers, paleo-ecologists, archaeologists or zoo-archeologists, and an historian. Twelve presentations and two posters were presented covering subjects ranging from paleoclimatology and paleoceanography, subarctic and circumpolar sea-ice proxies, biological productivity, human colonization histories, interaction with marine food webs, and development of intensive commodity-driven fisheries. In addition, the working group met in two break-out sessions to frame and flesh out a series of integrative research themes that will ultimately structure the development of a special issue on the paleoecology, anthropology and history of the seasonally frozen northern hemisphere seas from the Late Glacial Maximum to recent centuries.

Goals of the working group meeting were:

  • to introduce a paleoceanographic and paleoecological perspective to ESSAS, with attention to scales of change and dynamics at longer phases than instrumental records permit;
  • to integrate the history of human engagement in the subarctic marine ecosystems; and
  • to draw relevant insights from comparative analyses of time and space.

The WGPESAS discussions explored questions that could best be answered with data from several different disciplines, to finer scale planning of how specific data sets could be combined to address the questions. The natural science questions were derived from some unsolved puzzles in the archaeology and history of the subarctic regions. Discussions of these problems led quickly to the recognition of possible connections and synergies with processes and transitions in the paleoclimatology, paleoceanography, and paleoecology data sets. From this starting point, the PESAS group aims, over the next two years, to explore correlations and potential mechanisms linking climate, oceanographic, ecological and human system relationships at the four time scales in the past that are summarised below.

TIME FRAME 1: Glacial – Deglacial Subarctic Ecological Dynamics and the Peopling of the Americas.

Long standing questions in the archaeology of the Americas are when and how humans first migrated to these continents. Discoveries in recent decades suggest that it is most likely that migration/s occurred during the Late Glacial, perhaps between 20,000 and 15,000 BP and by a coastal route – either around the North Pacific (most likely) or the North Atlantic (plausibly). While archaeological record shows that the possible coastal migration routes would now be more than 120-150 meters below sea level, better understanding of the climatology and paleoecology of the subarctic North Atlantic and North Pacific regions could provide insights into the most likely routes and timing of human movement. WGPESAS members plan to explore these issues using models and proxy data to compare the conditions in the 20-15 Kya interval to those between 15-10 Kya. Of interest are winter temperatures, storminess, sea-ice extent and variability, ocean currents, freshwater runoff and stratification/mixing, nutrient supply (e.g. iron in the North Pacific, silica in the North Atlantic), primary productivity, and trophic feeding dynamics.

TIME FRAME 2: Mid-Holocene Regime Shifts, 6000-4000 BP

In the North Pacific, humans do not appear to have settled the seasonally frozen coasts and islands until 5,000 BP or later. This is in contrast to the adjacent unfrozen coasts (where warm ocean currents modify coastal temperatures) where there is concrete evidence of occupation at least 10,000 BP or more. In the North Atlantic, there is a similar pattern, and the more moderate coastal zones of Northern Europe were settled by maritime peoples over 10,000 BP, while the seasonally frozen coasts of NE North America were only settled in the last 6,000-7,000 years. In the North Pacific, proxy evidence from marine cores indicate major increases in marine primary productivity around 5000 BP. This was also when seasonality was starting to decrease and summer temperatures were cooling substantially. Changes in the position of the Siberian High and Aleutian Low tracks, reductions in winter sea ice and increased productivity may all have facilitated the expansion of human settlement and subsistence into the subarctic marine environment. We will examine changes in climatology, sea-ice cover, productivity, and human settlement distributions in the context of known mechanisms of ocean-atmospheric coupling.

 

TIME FRAME 3: Late Holocene Density-dependence, Intensification, and Demographic Oscillation: The North Pacific from 2000 – Present.

Human populations expanded in the subarctic during the late Holocene resulting in large, semi-sedentary populations around much of the North Pacific and North Atlantic rims. By the late Holocene they were engaged in intensive exploitation of marine resources with specialised technologies, techniques for evening out the seasonal variability of resources, and even ownership of natural resource patches in some areas. Two of these populations – in the Kuril Islands and the Lower Alaska Peninsula – show inverse patterns of population growth and decline over the past 2000 years. One hypothesis to explain this asynchronous pattern is an oscillating ecosystem dynamic, such as the Pacific Decadal Oscillation, only at multi-century scales. The increased density-dependence of human populations on an intensifying subsistence existence may have rendered these populations more vulnerable to negative perturbations in their food supply. The east-west oscillation in available food might relate to shifts in the positions of the Siberian High and the East Asian monsoon/Aleutian Low storm track, and the associated effects on the direction and intensity of winds, upwelling, hydrography, and productivity. An alternative hypothesis is the propagation of oceanic Rossby waves from the tropics into the North Pacific. Paleoclimatological and oceanographic data will help determine changes in the position of the East Asian Monsoon and Aleutian Low, sea ice, and primary productivity during this 2000 year time interval. Zoo-archaeological and other upper trophic productivity and diversity data can be used to examine east-west changes in economically important resources available to, and utilised by, human consumers. While this time frame explicitly addresses an emergent question about the North Pacific, we aim to examine North Atlantic evidence for similar asymmetries that could be tied to climate-ocean dynamics.

TIME FRAME 4 – Commercialization of the Subarctic – 1000-present.  N. Atlantic and N. Pacific.

Whereas subsistence-oriented cultures faced density-dependent limits in the exploitation of the marine resources on which they depended, growth in the commercial exploitation of fish, whales, and fur-bearing sea mammals increased during the last 1000 years in the North Atlantic, and into the 18th to 20th centuries in the North Pacific. Explorers and entrepreneurs, and by extension, the markets they participated in, found their way into every subarctic cove and bay by the late 20th century. Overhunting of whales, overfishing of cod and the near extinction of the sea otter, were the result of the expansion of the globalized market into subarctic regions. Starting with the Norse colonisation of the North Atlantic shortly before 1000 BP, we see how large, globalized markets can undermine regional ecological stability. European whaling (e.g. Basque, English, Dutch); cod fishing (e.g. Scandinavian, Basque, Portuguese); and the fur trade (e.g. Russian, British, Chinese) commoditised subarctic “ecosystem services” and created a demand large enough to severely impair stocks. These impacts occurred where there was contact between indigenous communities and commercial entrepreneurs. It happened against a backdrop of climate changes and variable weather. The experiences have been documented in varying extents, and the working group will focus on both the written history and the archaeological and environmental proxies. This last time frame allows us to address shorter scales of temporal variability, from the deep past to the present. 

The abovementioned questions and hypotheses will motivate the research of the working group over the next two years. Next year, disciplinary syntheses, focusing on high resolution studies of the time intervals identified above, with lower resolution coverage of the intervening intervals will be carried out. These will be presented at the next ESSAS Annual Science Meeting (ASM) (Seattle, June 2015). In the second year, the project will focus on the integration of the various disciplinary research results into an overall synthesis.  

     
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IMBER-related Research and Activities 

Anoxia in the Far Eastern Marine Biosphere Reserve (Peter the Great Bay)

Pavel Tishchenko1, Victor Ivin2, Pavel Stunzhas3

1V.I. Il’ichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russia
2A.V. Zhirmunskiy Institute of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russia
3P.P. Shirshov Institute Oceanology Russian Academy of Sciences, Moscow, Russia

 

Hypoxia can cause serious problems in coastal areas, as well as oxygen minimum zones (OMZ) in the open ocean. Some regions in Russia experience permanent or seasonal hypoxia or/and anoxia. These are the Black Sea, Caspian Sea, Baltic Sea, Sea of Okhotsk, salt lakes in Siberia (e.g. Lake Shira) and shelf of the Sea of Japan. Natural processes tend to dominate the formation of hypoxia or/and anoxia in the Black Sea, Caspian Sea, Sea of Okhotsk (OMZ) and salt lakes in Siberia, while both natural and human-induced drivers cause hypoxia in the Baltic Sea and shelf of the Japan Sea (Amursky Bay, which is part of Peter the Great Bay, see Fig. 18a). Hydrochemical studies have been systematically carried out since hypoxia was discovered in Amursky Bay in 2007 (Tishchenko et al., 2013). In August 2013, scientists from the Institute of Marine Biology (Vladivostok), Institute Oceanology (Moscow) and the Pacific Oceanological Institute (POI, Vladivostok), discovered that seasonal anoxia occurs in the bottom waters of the Far East Marine Biosphere Reserve (FEMBR) (Stunzhas et al., 2014).

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Figure 18. a: Bottom depths and sites of hydrochemical stations in Posjet Bay (1) and the adjacent basins, including the southern part of the Far Eastern Marine Biosphere Reserve (within the yellow lines), 2 – Rejd Pallada Bay, 3 – Expeditsiya Bay, 4 – Furugelm Island. b: Distribution of dissolved oxygen concentration (umol/kg) in the bottom waters. c: Distribution of silicate concentrations (umol/l) in bottom waters. d: Vertical profiles of potential density (dashed lines) and percentage saturation of oxygen (solid lines) for stations 21 and 18, red and blue lines, respectively.

The FEMBR covers 10% of area of Peter the Great Bay, and consists of five parts. The southern part (see Fig. 18a) was the main focus of our study. The area around Furugelm Island is very beautiful (see Fig. 19a). It was consequently a shock when biologists from the Institute of Marine Biology (IMB), using the “SubFighter” submersible (Fig. 19b), discovered a “dead zone” at the bottom of the bay, only 2.5 kilometers from the island. Particularly, as no hypoxic areas had been observed during hydrochemical surveys carried out by POI in Posjet Bay and the adjacent area the month before.

 
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Figure 19. Life near Furugelm Island (Far Eastern Marine Biosphere Reserve, Peter the Great Bay). a: Seal at Rocky Mikhelson; b: Dead and decaying fauna on bottom of the Bay, 2.5 kilometers from Rocky Mikhelson.

Chemists from POI and Dr. Pavel Stunzhas, a visiting expert on vertical oxygen structure of the Black Sea from Shirshov’s Institute of Oceanology in Moscow, took vertical measurements of temperature, salinity, dissolved oxygen, turbidity, and fluorescence. Water samples from both the surface and bottom layers, using Niskin bottles, were analysed for salinity, dissolved oxygen (DO), nutrients (nitrates, nitrites, ammonium, phosphates, silicates), total alkalinity (TA), рН, hydrogen sulphide, chlorophyll concentrations, humic substances, dissolved organic carbon and Secci disk depth. Dissolved inorganic carbon (DIC) and CO2 partial pressure (pCO2) values were calculated. 

In the “dead zone” DO concentration was almost zero (Fig. 18b) but concentrations of silicates were high (Fig. 18c). Other chemicals (e.g. ammonium ions, phosphates, pCO2) were also high, ammonium ions (about 31 umol/l), phosphates (about 6.5 umol/l), pCO2 (about 1800 uatm) and it was found detectable level of concentrations of the hydrogen sulphide (about 1 umol/l) (Fig. 20).

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Figure 20. Distributions of chemical parameters in bottom waters. a – phosphates (umol/l); b – ammonium ions (umol/l); c – CO2 partial pressure (uatm); d – Dissolved Inorganic Carbon (umol/kg).

Hydrochemical data suggest that microbiological decay of dead “excess” diatoms in low light conditions (depths more than 21m) results in intense consumption of dissolved oxygen, and production of phosphates, inorganic nitrogen, silicates and dissolved inorganic carbon. Sulfate reduction occurs when the DO is depleted, causing most of the diatoms to die. It should be noted that the anoxic area that exhibited the hydrochemical anomalies, corresponds to coastal bottom depression located between Furugelm Island and a coast (Fig. 18a). Due to the weak dynamics of the bottom water within the depression, the supply of DO from surrounding waters into the depression is limited. The diatom bloom probably resulted from the high rainfall experienced in the summer of 2013. This caused high water discharge, together with high nutrient fluxes into Expeditsiya Bay, resulting in the production of “excess” diatoms. There are plans to investigate the formation of “excess” diatom production further.

     

References

  • Tishchenko P. Ya., Lobanov V. B., Zvalinsky V.I., Sergeev A.F., Koltunov A., Mikhailik T.A., Tishchenko P.P., Shvetsova M.G., Sagalaev S., and Volkova T.I. 2013. Seasonal Hypoxia of Amursky Bay in the Japan Sea: Formation and Destruction. Terr. Atmos. Ocean. Sci., 24 (6): 1033-1050.  
  • Stunzhas P.A., Tishchenko P.Ya., Ivin V.V., Barabanshchikov Yu.A., Volkova T.I., Vishkvartcev D.I., Zvalinsky V.I., Mikhailik T.A., Semkin P.Ju., Tishchenko P.P., Khodorenko N.D., Shvetsova M.G., Golovchenko F.M. 2014. Submitted. First caseof anoxia in the waters of fareastern marine reserve area. Dokladi Akademii Nauk
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Ocean Colour for Climate

Cat Downy1 and Shubha Sathyendranath2

1ESA-IGBP, European Space Agency Climate Office, ECSAT, Atlas Centre, Harwell Oxford, Didcot, Oxfordshire, OX11 0QX. UK. cat.downy@esa.int
2Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth, PL1 3DH, UK. shubha@dal.ca
http://www.esa-oceancolour-cci.org/

 

Obtaining accurate Ocean Colour measurements has become an important challenge for the climate research community, as they are recognised as an essential climate variable, with many useful applications, such as mapping chlorophyll concentration at the global scale. New ocean colour products, generated by a team led by the Plymouth Marine Laboratory and funded by the European Space Agency’s Climate Change Initiative, have been specifically designed for climate studies, providing better coverage and unprecedented characterisation of uncertainties.

Introduction

It is currently estimated that the productivity derived from ocean phytoplankton equals that of net terrestrial primary production (Lurin et al. 1994). This makes the oceans an important sink for CO2 and phytoplankton an important mediator in the global cycle of carbon. Phytoplankton are at the base of the food chain in the ocean, with all larger organisms in the pelagic ecosystem relying on them, directly or indirectly, for their food. The abundance of phytoplankton can be mapped by measuring variations in the absorption and scattering of light in the ocean. This is known as ocean colour radiometry; it allows us to infer spectral variations in remote-sensing reflectance in the visible domain of the electromagnetic spectrum, after suitable corrections are applied to the top-of-atmosphere signal detected by satellites.

The Global Climate Observing System (GCOS) has recognised ocean colour as an  “Essential Climate Variable” (ECV), required to support the work of the Intergovernmental Panel on Climate Change (IPCC) and the United Nations Framework Convention on Climate Change (UNFCCC). However, they have also highlighted the lack of continuity of climate-quality ocean colour observations. This is now being addressed by the Ocean Colour project of the European Space Agency’s Climate Change Initiative (CCI), which, over the last three years, has produced a 15-year climate-quality, merged ocean colour time series for use in climate change studies. 

Producing an Essential Climate Variable

An ocean colour data series suitable for climate research needs to be long, and have clearly defined errors. The process of obtaining this data series involved combining different satellite data records, each with its own sensor specifications, calibration issues and algorithms. In order to achieve this, a number of intermediate steps were necessary:

User requirements

User requirements underpin all Ocean Colour CCI activities; a survey and consultation were undertaken at the beginning of the project, incorporating the views of both modellers and observational scientists. These results, along with requirements from GCOS, form the basis of the design of the data products.

The Ocean Colour data products include remote-sensing reflectance in the visible domain, and derived chlorophyll concentration, in addition to a number of other optical properties computed from the radiances, such as various inherent optical properties and the diffuse attenuation coefficient for downwelling irradiance (Table 1). They utilise data from ESA’s MERIS and NASA’s SeaWiFS and Aqua-MODIS archives.

Algorithm selection

The selection of algorithms for the Ocean Colour CCI project is a key part of the development of the data sets: firstly, to correct for atmospheric effects that mask the signal from the ocean (atmospheric correction), and secondly to convert the retrieved ocean colour signal into biogeochemically relevant variables (in-water algorithms).

 

Many algorithms are available for both areas – each with their own limitations and advantages. To select the best one, a suite of criteria was developed that included qualitative considerations, such as the robustness of the algorithms in the event of potential modifications in the marine ecosystem in a changing climate. The quantitative performance of the algorithms was also evaluated using a suite of statistical tests on satellite products matched with in situ observations. This process led to a significant improvement in the spatial coverage of data from the MERIS sensor (Müller et al. 2013), as seen in Fig. 21. The algorithm selection procedures have the potential to be routinely implemented, so that the performance of emerging algorithms can be compared with existing algorithms as they become available (Brewin et al. 2013).

Achieving climate-quality data

The GCOS requirements identified time series data of spectrally-resolved remote-sensing reflectance and chlorophyll-a as a priority. However, as the three ocean colour sensors used in the project each have different sets of spectral bands, a reference sensor had to be selected and the remote-sensing reflectance wavebands of the other sensors shifted to that of the reference sensor (SeaWiFS). This ensures continuity of product at the same wavelength. This “band-shifting” was also essential to establish inter-sensor biases, which had to be corrected, to avoid spurious trends in time series data: a flaw to be avoided in a time series designed for climate change studies.

A major achievement of the project was devising a method to provide pixel-by-pixel error characterisation for the merged product. The uncertainties provided include root mean square error and bias, based on validation with in situ data. This was achieved through the use of optical classification of pixels, and optical-class-based uncertainty characterisation. A new integrated in situ database was set up from a number of available sources and matched with satellite data to establish the uncertainty characteristics. The database also provides the basis for the validation exercises, which also comprises a number of comparison exercises, designed to evaluate the consistency of the data products.  

This first version of the Ocean Colour CCI data set provides better coverage, better error characterisation and bias correction whilst meeting the GCOS requirements for temporal resolution and accuracy. It has recently been assessed by ocean colour and ecosystem modelling experts within the project who provided feedback for the next stage of the data set development. Feedback from all users is welcomed.

The Climate Change Initiative

The Ocean Colour CCI project runs in parallel with 12 other projects in ESA’s Climate Change Initiative programme, all of which are developing Essential Climate Variables. The projects aim to produce stable, long-term, multi-sensor time series of satellite data with specific information on errors and uncertainties. A Climate Modelling User Group provides a forum for interaction with climate modellers, to ensure the products are useful to the modelling and data assimilation community. All data products are freely available online and all documentation pertaining to data set development is accessible on the project websites.   

     
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Figure 21. Improvements in the Essential Climate Variable are apparent in the improved coverage of the Ocean Colour CCI product over the Arabian Sea.

 
 

Table 1: Detail of the Ocean Colour Essential Climate Variable data sets and where to access them.

Ocean Colour products
Data Access: http://www.esa-oceancolour-cci.org/ 

For all products:

Spatial coverage: Global           Temporal resolution: Daily and Monthly                 Temporal coverage: 1997-2012

Property Sensors Spatial grid Explanatory text
Phytoplankton Chlorophyll-a concentration (chlor_a) [mg m-3] GCOS Climate Variable  MERIS, Aqua-MODIS, SeaWiFS  4x4 km  These are level 3 binned, multi-sensor merged, as sinusoidal and geographic products. Uncertainty layers are also included. This is a key OC product. 
Remote-sensing reflectance (Rrs) at 6 wavelengths [sr -1] GCOS Climate Variable  MERIS, Aqua-MODIS, SeaWiFS  4x4 km  These are level 3 binned, multi-sensor merged, as sinusoidal and geographic products. Uncertainty layers are also included. This is a key OC product.
Diffuse attenuation coefficient for downwelling irradiance (kd_490) [m-1 MERIS, Aqua-MODIS, SeaWiFS  4x4 km  These are level 3 binned, multi-sensor merged, as sinusoidal and geographic products. Uncertainty layers are also included. 
Total absorption (atot) and backscattering coefficients (bbp) [m-1] at 6 wavelengths  MERIS, Aqua-MODIS, SeaWiFS  4x4 km  These are level 3 binned, multi-sensor merged, as sinusoidal and geographic products. No uncertainty layers as atot is a combined product and there is insufficient data for bbp. 
Phytoplankton absorption coefficient (aph) [m-1 MERIS, Aqua-MODIS, SeaWiFS  4x4 km  These are level 3 binned, multi-sensor merged, as sinusoidal and geographic products. 
Absorption coefficient for dissolved and detrital material (adg) [m-1 MERIS, Aqua-MODIS, SeaWiFS  4x4 km  These are level 3 binned, multi-sensor merged, as sinusoidal and geographic products. 

References

  • Lurin, B, Rasool, SI, Cramer, W and Moore, B. 1994. Global terrestrial net primary production. Glob. Change NewsL (IGBP) 19: 6-8. 
  • Müller et al. 2014. A Methodology for assessing atmospheric correction processors based on in-situ measurements, Remote Sensing of Environment (in press). 
  • Brewin et al. 2013. The Ocean Colour Climate Change Initiative: A round-robin comparison on in-water bio-optical algorithms, Remote Sensing of Environment. http://dx.doi.org/10.1016/j.rse.2013.09.016
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The Austral Summer Institute XIV (ASI XIV) at University of Concepción, Chile 

Mónica Sorondo and Silvio Pantoja

Department of Oceanography, University of Concepción, Chile

 

The Austral Summer Institute XIV (ASI XIV), organized by the Department of Oceanography and the COPAS Sur-Austral Program of the University of Concepcion, Chile, was devoted to topics on Coastal and Open Ocean Studies through Multiple Approaches. ASI’s activities were held during January 2014 and consisted of three courses at the Main Campus of the University of Concepcion and one course held at the Marine Biological Station in Dichato.

The course “Changing biogeochemical cycles in the coastal ocean” by Professor Dr. Kay-Christian Emeis from the University of Hamburg, Germany, was held on 6-10 January 2014 and was attended by 19 students coming from Argentina, Chile, Brazil, Belgium, Colombia, Cuba, Germany, Uruguay and the United States. 

The course provided participants with information and techniques that enabled them to appreciate the roles of shelf seas and coastal systems in material cycles, to evaluate the consequences of enhanced and altered material cycles for regional subsystems, and to anticipate the subsequent chances and risks for human society emerging from these changing biogeochemical cycles. In topical lectures and practical exercises, the course reviewed some of the basics of biogeochemistry and students became acquainted with some useful tools that help us in analysing data, understanding interactions, and assessing the status of typical coastal systems 

The Austral Summer Institute continues to contribute to capacity building in Latin America each year, enabling the development of networks among local and visiting scientists and students (http://www.udec.cl/oceanoudec/asi-14/).

Testimonials: 

Pedro Marone Tura

Master’s Program in Biological Oceanography
Institute of Oceanography of the University of São Paulo (USP), Brazil  

I was asked to write about my experience in the ASI XIV courses, taken in early 2014 in Concepción – Chile, at the Universidad de Concepción (UDEC). It is hard to express in words this experience, or to decide which my greater gain as post-graduation student was. Maybe it was the theoretical content presented by great professionals from the international scientific community that spared no effort to instruct us, a heterogeneous group of students from different countries, the main issues discussed in their field. Maybe my greatest gain was to present and discuss my actual line of work to all this diversified group of professionals and be able to apply, in my daily work, the knowledge obtained. Or maybe it was all the pleasurable conversations, the group work and the exchange of experience with colleges and professors. As said before, it is hard to say which my greatest experience was, but undoubtedly all those days in ASI added new perspectives to my professional and personal ideas. My sincere acknowledgment to those responsible for this amazing experience.

 

Natalia Venturini

Postdoctoral Researcher at the Laboratory of Marine Organic Chemistry
Oceanographic Institute, University of São Paulo, Brazil

I am Natalia and I am from Uruguay, a little beautiful country in South America located between “two giants” Argentina and Brazil. I think that the possibility to participate in the last ASI XIV represented a remarkable experience for several reasons. First, because I had the opportunity to meet people from different countries (Chile, Belgium, Brazil, Argentina, Cuba, Ecuador, and Germany), cultures and religions and to spend a week with them not only in the classroom, but also, living together in a hostel. Particularly, our group was very close. Also, the course achieved my previous expectations and I learned a lot about several things such as eutrophication effects on biogeochemical cycles in coastal areas, LOICZ work and the STELLA model. Professor Kay Emeis was very cordial and always available to help us during the practical lessons, and as he said in his last speech, the ASI XIV was also a very good experience for him. Finally, I think these instances constitute the first step for the establishment of future cooperation with scientists from other parts of the world, so we have to draw on them.

Vanesa Negrín

Assistant Researcher-CONICET
 Chemical Oceanography
 Instituto Argentino de Oceanografía (IADO-CONICET), Argentina

I attended the course “Changing biogeochemical cycles in the coastal ocean“of ASI XIV in Concepción, Chile, and it was a very rewarding experience. The course was really interesting; I learnt about other coastal areas and I was introduced to new useful tools in ocean biogeochemistry (models). In addition, it was an opportunity to interact with the professor and my classmates, who work in different areas of oceanography all over the world. I really enjoyed the course and I thank IMBER for financing my accommodation in Concepcion.

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The Comings and Goings of IMBER

New Scientific Steering Committee (SSC) Members

IMBER is pleased to introduce the four new members who joined the IMBER Scientific Steering Committee this year.

Edward Allison is a professor at the School of Marine and Environmental Affairs at the University of Washington, Seattle, USA. His expertise includes fisheries assessment and management, and he served as technical and policy advisor for various international organisations in developing countries. Eddie’s research focuses on the contribution of fisheries and aquaculture to food security, the governance of small-scale fisheries and rights of fishers, and the vulnerability and adaptation of coastal communities to climate change.

eha1@uw.edu

 
Edward Allison
     

Laurent Bopp is affiliated with the French CNRS and leads a research group at the Laboratoire des Sciences du Climat et l'Environnement (LSCE) in Gif sur Yvette, France. His research focuses on the interactions between marine biogeochemistry and climate, with particular emphasis on marine elemental cycles, ocean acidification, and biogeochemical modelling. The activities of his research group are directed at quantifying the ocean's contribution to the global budget of greenhouse gases and how human disturbances, such as warming and acidification, impact ocean biogeochemistry.

laurent.bopp@lsce.ipsl.fr

 
Laurent Bopp
     

Gerhard Herndl is the Marine Biology Chair and head of the Department of Marine Biology at the University of Vienna, Austria. He is a leading researcher in microbial oceanography and a driving force in the exploration of microbial and biogeochemical processes in the deep ocean. His research group focuses on the microbial oceanography of the deep ocean. They are working to develop and improve molecular biology and biogeochemistry methods for studying deep-water metabolic pathways, and to make these applicable in oligotrophic regions of the ocean.

gerhard.herndl@univie.ac.at

 
Gerhard Herndl
     

Katrin Rehdanz is associate professor of environmental and resource economics at the University of Kiel in Germany, associated with the Kiel Institute for the World Economy. Her background is in environmental valuation and environmental-economy modelling. Her research interests include environmental and climate policy, global climate and environmental issues and strategies sustainable development and poverty reduction in developing countries. 

katrin.rehdanz@ifw-kiel.de

 
Katrin Rehdanz
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Farewell to Liuming Hu at the IMBER Regional Project Office in Shanghai, China

     

It is with great sadness that we will soon bid farewell to Dr. Liuming Hu, who is leaving IMBER. Liuming was appointed as Deputy Executive Officer at the IMBER Regional Project Office (RPO) in Shanghai, China in February 2011. Her first task was to establish the office, and in a very short time she threw herself headlong into all aspects of the IMBER project and proved herself to be an invaluable asset to IMBER.

Liuming has been the main point-of-contact for all IMBER-related activities and events in the Asia-Pacific region, and amongst other things, has been instrumental in organizing the successful, biennial IMBER China-Japan-Korea meetings.

Right from the start, Liuming has been a tremendous support for the International Project Office in Norway and will be sorely missed. We would like to thank her for all her hard work and to wish her everything of the best in her new endeavor. She is leaving to take up a new position in her home town - their gain is definitely IMBER´s loss!

 
Liuming Hu
     
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Publications

  • Bray L., Pancucci-Papadopoulou M. A. & Hall-Spencer J. M., in press. Sea urchin response to rising pCO2 shows ocean acidification may fundamentally alter the chemistry of marine skeletons. Mediterranean Marine Science. doi: 10.12681/mms.579 Article
  • Bromhead D., Scholey V., Nicol S., Margulies D., Wexler J., Stein M., Hoyle S., Lennert-Cody C., Williamson J., Havenhand J., Ilyina T. & Lehodey P., in press. The potential impact of ocean acidification upon eggs and larvae of yellowfin tuna (Thunnus albacares). Deep Sea Research Part II: Topical Studies in OceanographyArticle
  • Chambers R. C., Candelmo A. C., Habeck E. A., Poach M. E., Wieczorek D., Cooper K. R., Greenfield C. E., & Phelan  B. A., 2014. Effects of elevated CO2 in the early life stages of summer flounder, Paralichthys dentatus, and potential consequences of ocean acidification. Biogeosciences 11: 1613-1626. doi: 10.5194/bg-11-1613-2014. Article
  • Dang H. & Jiao N., 2014. Perspectives of the microbial carbon pump with special references to microbial respiration and ecological efficiency. Biogeosciences Discuss (11): 1479-1533. Article
  • Gazeau F., van Rijswijk P., Pozzato L. & Middelburg J. J., 2014. Impacts of ocean acidification on sediment processes in shallow waters of the Arctic Ocean. PLoS ONE 9(4): e94068. doi:10.1371/journal.pone.0094068 Article
  • Gattuso J.-P., Kirkwood W., Barry J. P., Cox E., Gazeau F., Hansson L., Hendriks I., Kline D. I., Mahacek P., Martin S., McElhany P., Peltzer E. T., Reeve J., Robert D., Saderne V., Tait K., Widdicombe S. & Brewer P. G., 2014. Free Ocean CO2 Enrichment (FOCE) systems: present status and future developments, Biogeosciences Discuss. 11: 4001-4046, doi:10.5194/bgd-11-4001-2014. Article
  • Geri P., Yacoubi S. El & Goyet C., 2014. Forecast of sea surface acidification in the Northwestern Mediterranean Sea. Journal of Computational Environmental Sciences 2014: 201819. doi:10.1155/2014/201819 Article
  • Guénette S., Araújo J. N. & Bundy A., in press. Exploring the potential effects of climate change on the Western Scotian Shelf ecosystem, Canada. Journal of Marine Systems. doi: 10.1016/j.jmarsys.2014.03.001 Article
  • Hofmann G. E., Evans T. G., Kelly M. W., Padilla-Gamiño  J. L., Blanchette C. A., Washburn L., Chan F., McManus M. A., Menge B. A., Gaylord B., Hill T. M., Sanford E., LaVigne M., Rose J. M., Kapsenberg L., &  Dutton J. M., 2014. Exploring local adaptation and the ocean acidification seascape – studies in the California Current Large Marine Ecosystem. Biogeosciences 11: 1053-1064. doi: 10.5194/bg-11-1053-2014 Article
  • Levin L. A., Liu K.-K., Emeis K.-C., Breitburg D. L., Cloern J., Deutsch C., Giani M., Goffart A., Hofmann E. E., Lachkar Z., Limburg K., Liu S.-M., Montes E., Naqvi W., Ragueneau O., Rabouille C., Sarkar S. K., Swaney D. P., Wassman P. & Wishner K. P., in press. Comparative biogeochemistry-ecosystem-human interactions on dynamic continental margins. Journal of Marine Systems. doi: 10.1016/j.jmarsys.2014.04.016 Article
  • Mattsdotter Björk M., Fransson A., Torstensson A. & Chierici M., 2014. Ocean acidification state in western Antarctic surface waters: controls and interannual variability. Biogeosciences 11: 57-73. doi: 10.5194/bg-11-57-2014 Article
  • Orr J. C. & Epitalon J.-M., 2014. Improved routines to model the ocean carbonate system: mocsy 1.0. Geoscientific Model Development Discussions 7:2877-2902. doi:10.5194/gmdd-7-2877-2014 Article
  • Orr J. C., Epitalon J.-M. & Gattuso J.-P., 2014. Comparison of seven packages that compute ocean carbonate chemistry. Biogeosciences Discussions 11:5327-5397. doi:10.5194/bgd-11-5327-2014 Article
  • Palmiéri J., Orr J. C., Dutay J.-C., Béranger K., Schneider A., Beuvier J. & Somot S., 2014. Simulated anthropogenic CO2 uptake and acidification of the Mediterranean Sea. Biogeosciences Discussions 11:6461-6517. doi:10.5194/bgd-11-6461-2014 Article
  • Taylor J. R., Lovera C., Whaling P. J., Buck K. R., Pane E. F., & Barry J. P., 2014. Physiological effects of environmental acidification in the deep-sea urchinStrongylocentrotus fragilis. Biogeosciences 11: 1413-1423. doi: 10.5194/bg-11-1413-2014 Article
  • Zhu Z.Y., Wu Y., Zhang J., Du J. Z., & Zhang G. S., 2014. Reconstruction of anthropogenic eutrophication in the region off the Changjiang Estuary and central Yellow Sea: From decades to centuries, Continental Shelf Research72, 152-162. doi: 10.1016/j.csr.2013.10.018 Article
 
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Meeting Calendar

2014

2015

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