Issue n°22 - December 2012
IMBER_Update_Dec12-new.pdf 2.59 MB
As the year is winding down, IMBER is gearing up for some exciting activities in the new year. IMBIZO lll takes place at the National Institute of Oceanography in Goa, India from 28 - 31 January 2013. The focused workshop format will provide the opportunity to explore the linkages and interactions between humans and ecological and biogeochemical systems in the continental margins and open ocean. We look forward to a stimulating meeting.
As at the previous IMBIZOs, a Data Management Workshop will be held the day before the start of the meeting. This one adds a new dimension, by considering good management practices, not only for natural science data, but also socio-economic data, and their integration. Staying on the topic of data, Kon-Kee Liu (IMBER Chair of the IMBER-LOICZ Continental Margins Working Group) recently attended the CODATA conference on open access data and you can read his report on the proceedings.
The science highlights in this issue focus mainly on work being carried out in the China Seas and Southern Ocean. IMBER is currently evaluating endorsement of the Sustainability of Marine Ecosystem Production under Multi-stressors and Adaptive Management (MEcoPAM) project. It aims to improve understanding of the impact of multi-stressors on the sustainability of marine ecosystem production in the China Seas. Five articles from scientists involved in this project are presented. Several scientists from IMBER's regional programme Integrating Climate and Ecosystem Dynamics (ICED) have also contributed articles. The report on the effects of a severe coastal storm on the deep ocean ecosystem presents some of the first results of the IMBER-endorsed DOSMARES project.
Report on the CODATA 23rd International Conference
Chair of the IMBER-LOICZ Continental Margins Working Group
CODATA, the Committee on Data for Science and Technology, held its 23rd International Conference from 28-31 October 2012 in Taipei, Taiwan. Kon-Kee (KK) Liu attended on behalf of IMBER. The theme of the meeting was Open data and information for a changing planet, which highlighted the role data-intensive science plays in transforming raw observations into applicable, intelligible results and discoveries. It also emphasized that scientific endeavours, and the data that sustain them, are key to providing reasoned solutions to the problems of climate change, population pressure, natural disasters, and other global issues. The conference brought together stakeholders from industry, research and academia to address these issues and put forward solutions that might benefit the future of the planet.
The main industries represented were publishing (particularly those promoting data publishing journals) and health care and financial organizations that rely on data management skills and technology. The academics at the meeting fell into two types – either ‘small’ (e.g. global change research) or ‘big’ sciences (such as high energy physics).
Publication in data journals were considered one of the best ways for sharing data. Many speakers mentioned that more effort is needed to get the best use out of existing data for hazard mitigation and disaster prevention. While this might be the case, it was disconcerting that some speakers suggested that using existing data more effectively is more important than collecting new data. It is, therefore crucial for the global change research community to identify important knowledge gaps for better stewardship of the future earth, to advocate the relevance to society of new scientific research, and to efficiently convert observational data into useful knowledge for effective environmental management.
Observations and comments
In his opening address, Dr. Yuen-Tseh Lee, President of the International Council for Science (ICSU), proclaimed that Future Earth (the new research initiative to develop knowledge for responding effectively to the risks and opportunities of global environmental change and for supporting transformation towards global sustainability in the coming decades) is the most important scientific initiative in the 21st Century.” During his presentation, Dr. Salvano Briceno, SC Chair of IRDR (Integrated Research on Disaster Risks) asserted that vulnerability is the most damaging aspect of natural disasters. In fact, ‘natural disasters’ are no longer natural, but strongly related to human conditions. Because of this, data on the vulnerability of human societies to natural disasters are much needed. However, compared to vulnerability, natural disasters are much better understood. In the final keynote speech, Prof. David Carlson, Director of the International Project Office of the International Polar Year (IPY), demonstrated how community involvement during IPY, and community monitoring of the environmental changes could be an important source of data.
During the topical session focused on Best Practices and Future Directions in Data Sharing, Dr. Charlotte Lee of the University of Washington presented a social scientist’s observation of scientific collaboration amongst health care professions. Scientific collaboration and data sharing were achieved through the establishment of a new culture, which relies on how scientists interact with each other.
There were several sessions organised for publishers and data centres, where data publication, data management and the long-term maintenance of data archives were discussed. Development in information-communication technology also received a lot of interest. There has been considerable progress in cloud-based (resources delivered as a service over a network) computation and data management in recent years and cloud applications could be a useful way to attract users to store and process, and eventually, share data. However, while the use of open data and information were promoted, it was stressed that “intelligent openness” should be the goal. Without structure and organization, vast amounts of open data would be useless.
Projects such as high-energy physics, astronomy or space research often produce large volumes of data and several cyber-infrastructures have been established to deal with this. Most global change research, however, is done on a much smaller scale and consequently produces less data. However, the complexity of the data involved means that it can be as difficult to handle as the very large volumes of data generated by ‘big’ science projects.
Many researchers use various IT technologies, such as: artificial intelligence, data mining, and the development of ontologies. However, this often means that the data or information is not widely available. The importance of involving the public in the processes of collecting and sharing data and information was stressed. While data and information about global environmental change are very relevant to the public, they are often not accessible.
It is desirable to develop ways to involve the public in scientific endeavors, such as monitoring environmental changes. Such practices could increase public interest in global change research and improve understanding of the potential hazards that could affect us all in the future. It could result in a culture of data sharing by the public as well as among the professionals.
Spatial and temporal variability of sea surface temperature in the Yellow Sea and East China Sea over the past one and half centuries
The spatial and temporal variability of sea surface temperature (SST) in the Yellow and East China Seas (YES) were investigated using the Met Office Centre’s Hadley SST data (HadISST1). The SST in the YES for the last 141 years (1870-2010) is partitioned into the annual range and annual mean components. The spatial and temporal variability of the annual range and annual mean SST and their relationship were analyzed using the Empirical Orthogonal Function (EOF) method. The possible linkage between the identified variability and known regional and global climate conditions (i.e., the annual surface air temperature anomaly over China, El Niño–Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO)) was also explored.
Both annual range and annual mean SST varied on inter-annual to decadal time scales, and were significantly negatively correlated. This correlation suggests that a higher (lower) annual mean SST is associated with a smaller (larger) annual range. Therefore, years with higher (lower) annual mean SST, often have smaller (larger) annual range, and consequently experience much warmer (colder) than usual winter SST. The winter SST variability is the most significant of the four seasons, and the summer SST is the least variable.
Over the last 141 years, the annual mean SST in the YES has experienced four regimes - a cold regime with a cold trend from 1970 to 1900, a cold regime with a warm trend from 1901 to 1944, a warm regime with a cold trend from 1945 to 1976, and a warm regime with a warm trend from 1977 to 2010 (Left panel of Fig 1). Corresponding to these four regimes, the seasonal SST experienced a smaller, higher, normal and smallest annual range, respectively.
The SST in the YES during the last warm regime (from 1977 to 2010) increased from 0.6°C in the southeast to 2.0°C in the centre of the YES (Right panel of Fig 1). During this period, the annual range was significantly reduced. The combination of the warming of annual mean SST and the reduction of the annual range resulted in a much larger SST increase in winter, i.e., the warming in winter was much more significant than in the other seasons of the last warm regime, and particularly in 1998.
Both the annual range and annual mean SST in the YES are related to the regional and global climate. The warmer (colder) surface air temperature over China is associated with a warmer (colder) SST in the YES, particularly in winter, due to the higher (lower) annual mean SST and smaller (larger) annual range.
The small correlation coefficient between both annual mean SST and annual range with ENSO and PDO indexes mean that annual mean SST and annual range are definitely related to the variability of the large scale Tropic Ocean and North Pacific Ocean climate, but the contribution from the global climate to the variability of annual mean SST and annual range in the YES is only about 15-20%. The relatively larger correlation coefficient between the annual mean SST and annual range with the TAC index means that regional climate is more closely related to the variability of SST in the YES.
Huang D., Ni X., Tang Q., Zhu X. & Xu D. (2012), Spatial and Temporal Variability of Sea Surface Temperature in the Yellow Sea and East China Sea over the Past 141 Years, Modern Climatology, Dr Shih-Yu Wang (Ed.), ISBN: 978-953-51-0095-9, InTech, Available from: http://www.intechopen.com/books/modern-climatology/spatial-and-temporal-variability-of-sea-surfacetemperature-in-the-yellow-sea-and-east-china-sea-ove
Rayner N.A., Parker D.E., Horton E.B., Folland C.K., Alexander L.V., Rowell D.P., Kent E.C. & Kaplan A. (2003), Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century. Journal of Geophysical Research, 108(D14), 4407, doi:10.1029/2002JD002670
A New Strategy for Coping with Climate Change in China - Mariculture
Jianguang Fang, Zengjie Jiang, Jihong Zhang, Yuze Mao, Wei Wang
Key Laboratory for Sustainable Utilization of Marine Fisheries Resources, Ministry of Agriculture, Carbon Sink Fisheries Laboratory, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China
The release of carbon dioxide into the atmosphere through the burning of fossil fuels or industrial discharge is currently one of the most important environmental issues. According to an assessment of the Intergovernmental Panel on Climate Change (IPCC) it may reach 20 billion tons/year by 2100 (from 7.4 billion tons/year in 1997) and the concentration of CO2 in the atmosphere could double by the middle of the 21st century, with disastrous environmental consequences. The Panel also identified key research needs in several aspects of carbon sequestration, including technology for separating and capturing CO2 from energy systems and sequestering it in the oceans or geological formations, or possibly by enhancing the natural carbon cycle of oceans, forests, vegetation, soils and crops. It also describes advanced options for chemically or biologically transforming CO2 into potentially marketable products (IPCC, 2007).
Mariculture in China
Mariculture is an extremely important component of the fisheries in China. Currently, it is the only country in the world where the total aquaculture output exceeds the catch. About 2.6 million ha of shallow sea, mud flats and bays in China are suitable for marine animal and plant culture. Mariculture in China is very developed, and both the extent of cultured areas and annual production are relatively high and continue to increase. The Food and Agriculture Organization (FAO) data show that in 1955 the total annual Chinese mariculture production was 0.1 Mt, and this has been steadily increasing. The industry has expanded dramatically since 1990, and output increased from ~1.6 Mt to ~13.1 Mt in 2007, (representing ~2⁄3 of total world mariculture production). This increase was largely driven by shellfish and seaweed mariculture in the shallow coastal waters. In 2010, the total annual yield of mariculture was more than 14 Mt, of which, seaweed and shellfish accounted for 86% of the total production (Fig. 2). Four main species of bivalves are cultured commercially: oysters, clams, scallops and mussels. Seaweed cultivation began in the 1950’s and the ribbon weed, Laminaria japonica was the first species to be cultivated. Production has risen from 62 t in 1952 to the current harvest of more than 1.5 Mt. The main species of cultured seaweed are Laminaria, Gracilaria, Undaria and Porphyra.
The Impact of Shellfish and Seaweed Mariculture on the Marine Carbon Cycle
Mariculture plays an important role in the coastal carbon cycle. Seaweeds can transform dissolved inorganic carbon (DIC) into organic carbon by photosynthesis, which can decrease the partial pressure of carbon dioxide (pCO2) in seawater. Dissolved nutrients, such as nitrates and phosphates, are taken up during photosynthesis, raising the alkalinity of surface water, which further reduces seawater pCO2, and consequently improves the rate at which atmospheric CO2 diffuses into the seawater. Shellfish utilize oceanic carbon during feeding and calcification. The effective filter-feeding system and high filtration rates of shellfish can result in the removal of phytoplankton and particulate organic material from whole embayments. In a large-scale shellfish mariculture area, this filter-feeding activity can strongly affect the biomass of phytoplankton and the amount and composition of particulate organic carbon (POC). Through the calcification process, carbon is embedded in the shells of bivalves as CaCO3. However, shellfish also continuously release CO2 into seawater through respiration and calcification processes (Frankignoulle 1994; Chauvaud et al 2003; Claire et al 2007). Respiration induces CO2 release through the aerobic oxidation of organic carbon, whereas calcification mainly results in shifts in the seawater carbonate equilibrium through the generation of dissolved CO2. Mariculture therefore, significantly affects CO2 concentration in seawater. Based on the carbon content data of both shellfish and seaweed, and annual production data from 1999 to 2008, it is estimated that 3.79 ± 0.37 Mt C/yr are absorbed, while at least 1.20 ± 0.11 Mt C/yr are removed from coastal ecosystems (Tang et al 2011).
Adaptive Management Strategy
Integrated Multi-Trophic Aquaculture (IMTA) has been proposed a farming method with the potential to mitigate some of the environmental problems associated with monoculture, and to increase total production at a given site (Neori et al 2000; Chopin et al 2001; Ridler et al 2007; Neori et al 2007). Of particular interest is the combination of shellfish and seaweed culture. This is based on the concept that seaweed actively take up CO2, release O2 into the surrounding environment, and utilize the metabolic waste from the shellfish as nutrients. As a result, seaweed can create a favourable environment for shellfish growth (Evans et al 2001; Langdon et al 2004; Mao et al 2009; Nunes et al 2003). Recent microcosm research indicated that the integrated culture of the seaweed Gracilaria lemaneiformis and scallop Chlamys farreri could provide an efficient and environmentally friendly means to reduce CO2 emissions from bivalve mariculture. A ratio of bivalve:seaweed of less than 1:0.96 may produce a stronger CO2 sink.
Chauvaud L., Thompson J.K., Cloern J.E., et al. Clams as CO2 generators: the Potamocorbula amurensis example in San Francisco Bay. American Society of Limnology and Oceanograpy 48(6): 2086-2092 (2003).
Chopin T., Buschmann A.H., Halling C., et al. Integrating seaweeds into marine aquaculture systems: A key toward sustainability. Journal of Phycology 37(6): 975-986 (2001).
Claire G., Franck G., Dominique D. Secondary production, calcification and CO2 fluxes in the cirripedes Chthamalus montagui and Elminius modestus. Ecosystem Ecology DOI: 10.1007/s00442-007-0895-8 (2007).
Evans F., Langdon C.J. Co-culture of dulse Palmaria mollis and red abalone Haliotis rufescens under limited flow conditions. Aquaculture 185:137-158 (2001).
Frankignoulle M., Canon C., Gattuso J.-P. Marine calcification as source of carbon dioxide: positive feedback of increasing atmospheric CO2. American Society of Limnology and Oceanograpy 39: 458-462 (1994).
IPCC AR4 SYR. "Summary for Policymakers". In Core Writing Team; Pachauri, R.K; and Reisinger, A. Climate Change 2007: Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. IPCC. ISBN 92-9169-122-4 (2007).
Langdon C., Evans F., Demetropoulos C. An environmentally sustainable, integrated, co-culture system for dulse and abalone production. Aquaculture Engineering 32:43-56 (2004).
Mao Y.Z., Yang H.S., Zhou Y., Ye N.H., Fang J.G.. Potential of the seaweed Gracilaria lemaneiformis for integrated multi-trophic aquaculture with scallop Chlamys farreri in North China. Journal of Applied Phycology 21: 649-656 (2009).
Neori A., Shpigel M., BenEzra D. A sustainable integrated system for culture of fish, seaweed and abalone. Aquaculture 186(3-4): 279-291 (2000).
Neori A., Troell M., Chopin T., et al. The need for a balanced ecosystem approach to blue revolution aquaculture. Environment 49: 36-43 (2007).
Nunes J.P., Ferreira J.G., Gazeau F., Lencart-Silva J., Zhang X.L., Zhu M.Y., Fang J.G. A model for sustainable management of shellfish polyculture in coastal bays. Aquaculture 219: 257-277 (2003).
Tang Q.S., Zhang J.H., Fang J.G. Shellfish and seaweed mariculture increase atmospheric CO2 absorption by coastal ecosystems. Marine Ecology Progress Series 424:97-104 (2011).
Ridler N., Wowchuk M., Robinson B., et al. Integrated multi-trophic aquaculture (IMTA): a potential strategic choice for farmers. Aquaculture Economics & Management 11: 99-110 (2007).
Distribution patterns of mobile mud in the East China Sea and their environmental implication
Jinlong Wang, Jinzhou Du, and Jing Zhang
State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, P.R.China
Coasts and the adjoining continental shelves are the primary interface between terrestrial and ocean environments. Sediment containing organic matter from river deltas, continental shelves and even the open sea, are considered to play a key role in global biogeochemical cycles as they are regarded to be the main repositories of organic matter in marine sediments (Aller, 1998; Corbett et al., 2004; Ducan A.Mackay, 2011). Particulate material with its adsorbed matter are typically deposited and resuspended several times before permanent accumulation or transport off the shelf. The time scales of these events are important parameters in understanding marine biogeochemical processes in the benthos and the water column. These include diagenetic reactions that occur in the sediments, the composition of buried material, and nutrient and oxygen availability in the overlying water (de Jonge and van Beusekom, 1995; Aller, 1998., Giffin and Corbett, 2003; Tengberg et al., 2003).
Using distribution patterns of mobile mud collected in May and August 2011 in the East China Sea, it was found that mobile mud values were high in the north of the estuary in August and there was a large non-mobile mud zone in the open sea. In May, mobile mud values were high in the south of estuary and in the open sea. The moisture content of the mobile mud was higher than in the surface sediments in both May and August. Although the grain size distribution pattern was similar in both months, grain sizes tended to be smaller in the mobile mud than in surface sediments. The distribution of 7Be in surface sediments along the coast and 234Thex in the mobile mud was similar to the high values that occurred in the south of Hangzhou Bay in May and August. Activity of 137Cs was higher in the south than in the north in both months. Activity of 137Cs and 234Thex increased from the coast to the open sea only in August. 210Pbex exhibited a similar pattern in both May and August. The activity ratio of 7Be and 210Pbex was high in the river mouth in May and further out to sea in August.
During May and August, the predominant source of mobile mud is the Changjiang River. However, the sediment balance indicated that reworking processes or other sources are the major providers of mobile mud. The high 7Be/210Pbex of mobile mud in the depleted oxygen zone suggested that terrestrial sourced materials are important in forming and maintaining the depleted oxygen zone in the East China Sea. Our observations may provide new understanding of the benthic processes that occur and the formation, development and disappearance of the depleted oxygen zone in the East China Sea.
Nishri A., Herman G. & Shlichter M. The response of the sedimentological regime in Lake Kinneret to lower lake levels. Hydrobiologia 339, 149-160 (1996).
Tengberg A., Almroth E & Hall P. Resuspension and its effects on organic carbon recycling and nutrient exchange in coastal sediments: in situ measurements using new experimental technology. Journal of Experimental Marine Biology and Ecology 285-286, 119-142 (2003).
Aller R.C. Mobile deltaic and continental shelf muds as suboxic, fluidized bed reactors. Marine Chemistry 61, 143–55(1998).
McKee B.A., Aller R.C., Allisona M.A., Bianchi T.S. & Kineke G.C. Transport and transformation of dissolved and particulate materials on continental margins inﬂuenced by major rivers:benthic boundary layer and seabed processes. Continental Shelf Research 24, 899–92 (2004).
Corbett D.R., McKee B.A. & Duncan D. An evaluation of mobile mud dynamics in the Mississippi River deltaic region. Marine Geology 209, 91–112(2004).
Giffin D. & Corbett D. R. Evaluation of sediment dynamics in coastal systems via short-lived radioisotopes. Journal of Marine Systems 42, 83-96 (2003).
Mackay D.A. & W.Dalrymple R. Dynamic mud deposition in a tidal environment: the record of fluid-mud deposition in the cretaceous bluesky formation,Alberta, Canda. Journal of Sedimentary Research 81, 901-920(2011).
Aller R.C. Conceptual models of early diagenetic processes: The muddy seaﬂoor as an unsteady, batch reactor. Journal of Marine Research 62, 815–835 (2004).
de Jonge V.N. & van Beusekom J.E. E. Wind and Tide Induced Resuspension of Sediment and Microphytobenthos from Tidal Flats in the Ems Estuary. Limnology and Oceanography 40, 766-778 (1995).
Distribution of planktonic ciliates in the Yellow Sea: its relationship with hydrography
Wuchang Zhang1*, Ying Yu1, 3, Cuixia Zhang1, 3, Feng Zhou2, 4, Nan Zhao1, 3 and Tian Xiao1
1Key Laboratory of Marine Ecology and Environmental Sciences, IOCAS, Qingdao, PR China
3University of Chinese Academy of Sciences, Beijing, PR China
4Department of Ocean Science and Engineering, Zhejiang University, Hangzhou, PR China
Planktonic ciliates are important components of microzooplankton assemblages. They are the trophic link between the microbial food web and metazoans. As primary consumers of pico- and nano-sized producers, and important food sources for metazoan zooplankton and fish larvae, ciliates play an important role in carbon and energy fluxes in pelagic marine systems.
The Yellow Sea is a shallow (mean depth - 44m) marginal sea on the continental shelf of the western Pacific Ocean. In its central area, there is a trough 70-80m (maximum 103m) deep. During the cold part of the year (December-April), its waters are vertically well mixed due to surface cooling, strong winds and tidal mixing. In winter, a striking feature of this water body is the northward Yellow Sea Warm Current (YSWC) along the western side of the trough (Huang et al., 2005). There is a coastal thermal front between the cold coastal waters and the warm central YSWC (Huang et al., 2010). The intrusion of the YSWC stops from April to November. The water column becomes stratified, with a thermocline at 30-40m depth, below which lies Yellow Sea Cold Bottom Water (YSCBW), with a core area within a 10°C bottom water temperature isocline (Yu et al., 2006). In the shallow area of the YSCBW, there is a tidal front between the tidally mixed and thermally stratified waters.
Eight cruises were carried out in the southern Yellow Sea in 2006 (April, September, October and December) and 2007 (March, May, June and August). Two transects across the YSCBW area were investigated. This study considered the influence of the YSWC and YSCBW on the distribution of ciliates. We hypothesized that seasonal stratification and oceanic water intrusion are important for the heterogeneous distribution of ciliates.
Distribution of ciliates from December to April
From December to April, the temperature and salinity were vertically well mixed at most stations. Intrusion of the YSWC was obvious in both transects. The YSWC intruded approximately parallel to the direction of Transect 1. Surface temperature increased gradually from coastal stations (St. 11-13) to offshore stations (St. 13-17) along Transect 1. The YSWC was weak in December, with salinity of 33 at St. 16. The YSWC was strong in March and April and salinity was 33 at St. 13. The thermal front was near St. 16 in December and moved to St. 13 in March and April. High ciliate abundance occurred near St. 16 in December. In March and April, high ciliate abundance (>500 ind. L-1) appeared on the onshore side of the front, with temperatures <9.5 °C. At the offshore stations, ciliate abundance was lower than 200 ind. L-1: 17-148 ind. L-1 in March and 0-133 ind. L-1 in April, with the exception of the bottom of St. 15 (567 ind. L-1) (Fig. 4).
Along Transect 2, the warm, saline water centre was found at St. 14 (25) in March and April. Thermal fronts existed on both sides of the YSWC. Ciliate abundance was low in the centre of the YSWC and high on either side of it. Ciliate abundance was higher (>500 ind. L-1) on the onshore than the offshore side of the YSWC. In December, there was a warm water centre at St. 22 and St. 23 - not due to the YSWC, as the salinity was low (<32). There was strong front between St. 21 and St. 22 and a weak front between St. 14(25) and St. 27. Chla concentration and ciliate abundance in the warm water centre were low. On the onshore side of the two fronts, Chla concentration and ciliate abundance were high. Ciliate abundance was found to be high in areas of high Chla concentration. However, the maximum ciliate abundance value did not correspond with the maximum Chla value.
Distribution of ciliates from May to October
From May to October, there was a thermocline at all stations. The lower part of the thermocline was located at 30-40m depths. The temperature in the upper layer increased from May (~15 °C) to August (~25 °C) and then decreased until October (~22 °C). However, the bottom water retained its cold (<12 °C) character from the previous winter (defined as the YSCBW in this paper). Thermal stratification reached its maximum in August in both transects. The average ciliate abundance in the YSCBW was highest in August (956 ind. L-1) and lowest in September and October (<300 ind. L-1). The average ciliate biomass was highest in May (1.68 mg C L-1) and gradually decreased to <0.30 mg C L-1. In May and June, there was high ciliate abundance in the YSCBW, dominated by the tintinnid species Tintinnidium primitivum. From August to October, ciliate abundance in the YSCBW was lower than that in the waters above the thermocline.
The tidal fronts in the study area exhibited obvious temporal and spatial variations. They were distributed in the relatively shallow region during late spring and early summer and then moved to the deeper part of the transects during mid-summer and early autumn. In May and June, the tidal front was close to the nearshore region and was thus not obvious in either of the transects. There were strong tidal fronts in Transect 1 from August to October. However, a tidal front was observed in Transect 2 only in October. In October, a tidal front at the border of the YSCBW was strong in both transects: on both sides (between St. 12 and St. 13 and between St. 16 and St. 17) of the YSCBW in Transect 1 and only on the onshore side (between St. 23 and St. 24) of the YSCBW in Transect 2. High Chla concentrations and ciliate abundance frequently occurred in the front or on the coastal side of the front (Fig. 4).
Huang, D., Fan, X., Xu D. et al. Westward shift of the Yellow Sea warm salty tongue. Geophys. Res. Lett., 32, L24613, doi: 10.1029/2005GL024749 (2005).
Huang, D., Zhang, T. & Zhou, F. Sea surface temperature fronts in the Yellow and East China Seas from TMI data. Deep-Sea Res. II, 57, 1017-1024 (2010).
Yu, F., Zhang, Z., Diao, X. et al. Analysis of evolution of the Huanghai Sea Cold Water Mass and its relationship with adjacent water masses. Acta Oceanol. Sin., 28, 26-34 (2006).
Summer bottom hypoxia off the Changjiang Estuary: its past and current status
Zhuo-Yi Zhu1, Jing Zhang1, Ying Wu1, Ying-Ying Zhang1, Jing Lin1, Su-Mei Liu2
2Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, China
Hypoxia has been reported in the near-bottom waters off the Changjiang Estuary since the 1950s. The area of the hypoxic zone off the Changjiang Estuary increased from 1900 km2 in 1959 to over 15400 km2 in 2006 (Fig. 5). Most of the change occurred in the past 10 years, indicating that the extent of oxygen depletion has recently become more severe. It has also been reported that hypoxia in the near-bottom waters is rather unstable. The hypoxia can disappeared after one month and in winter when the water column is vertically well mixed, there is usually no oxygen depletion in the water column. This makes this hypoxic zone very different from those in other parts of the world, for example the Black Sea.
During 2006, which was a particularly dry year in the Changjiang Estuary, three cruises were conducted between June and October to study the process of oxygen depletion. In August, the hypoxic area (dissolved oxygen (DO), < 62.5 μM) in the northern region was over 15400 km2, which is comparable to that in the Gulf of Mexico (Fig. 6). A large area of low DO (62.5 μM < DO < 94 μM) also was found in the southern region (Fig. 6). Data for the hypoxic zone pooled between 1959 and 2006 suggest that a dramatic increase in the area of hypoxia has occurred in recent years and that the centre of hypoxia is moving northwards. The location of the hypoxic zone is influenced by the Changjiang Diluted Water, which moves from year to year depending on Changjiang’s discharge and ocean environment.
Using the DO value and the area of the hypoxia zone, the volume of hypoxic water and the amount of oxygen that was depleted can be estimated. The depth of hypoxic water in August averaged 20 m. Given that the hypoxic area was 15400 km2, the volume of hypoxic water was 308 km3. The apparent oxygen utilization (AOU, the difference between the measured DO concentration and its equilibrium saturation concentration in water with the same physical and chemical properties) of the hypoxic waters averaged 171 μM, resulting in an estimate of 1.69×106 t for oxygen depletion. In August 1999, the volume of hypoxic water was 274 km3 and oxygen depletion was 1.59×106 t (Li et al., 2002).
Clearly, stratification and organic matter decay are responsible for oxygen depletion in the near-bottom columns. As can be seen, a typical profile of biogeochemical parameters can be found for the water column where bottom hypoxia was observed (Fig. 7). This phenomenon was also reported in former studies, but quantitative relationships still need to be identified (Fig. 8). For example, in August 2006, particulate organic carbon (POC), dissolved inorganic phosphorus (DIP) and apparent oxygen utilization (AOU) showed coupled variation in near-bottom waters. Significant relationships between AOU and bottom POC/DIP (r = –0.46, p < 0.001, n = 86) and between AOU and Δσ (r2 = 0.45, p < 0.001, n = 86, difference of surface and bottom water density) were also detected.
An investigation conducted in August 1999 suggested that the oxygen depletion area off the Changjiang Estuary has two parts - one in the northern region and the other in the southern region (Li et al., 2002). In 2006, we also observed these two regions of oxygen depletion. The occurrence of hypoxia was not consistent between the two regions and oxygen depletion seemed to occur separately in the two regions. For example, low DO in the southern region was repeatedly observed in June, August and October, but the area seldom became hypoxic. By contrast, obvious oxygen depletion in the northern region (i.e. DO <94 μM) was only observed in August, but it was very severe in both area and extent. However, a month later, the area of oxygen depletion was dramatically reduced to < 300 km2. Thus, oxygen depletion in the southern region is milder and longer-lived, whereas in the northern region, it is more severe and short-lived.
A simple and direct connection between bottom nutrients and AOU via the Redfield organic matter degradation equation is not apparent. However, the difference between the bottom AOU in the northern and southern regions is ~7% and the difference in bottom nutrients can be up to 70% (i.e., DIP). Thus, near-bottom waters in the northern region have a slightly higher AOU and a pronounced lower inorganic nutrient content, relative to the southern region (Fig. 5). Possible reasons for this can be the difference in organic matter stoichiometry in the surface waters, differences in terrestrial input to the respective regions, and/or differences in community respiration rates. Due to insufficient organic nutrients data, the role of DOP remains unknown for August 2006. Further study is needed to reveal the different coupling of AOU and DIP between the northern and southern regions (Fig. 9).
During summer of 2011, a further investigation of regions where hypoxia was reported was conducted. Although no operationally-defined hypoxia (i.e., DO < 2 mg/L) was observed, a large area (10 000 km2) of oxygen depletion was found. A similar estimate was made for the amount of oxygen depleted. This was found to be 1.19 ×106 t, compared with 1.69×106 t oxygen for the hypoxic waters in August 2006.
[The oxygen depletion work undertaken in 2006 has been published – see Zhu et al., 2011).
Zhu, Z.-Y., Zhang, J., Wu, Y., Zhang, Y.-Y., Lin, J. and Liu, S.-M. Hypoxia off the Changjiang (Yangtze River) Estuary: Oxygen depletion and organic matter decomposition. Marine Chemistry, 125(1-4): 108-116 (2011).
Short- and long-term consistency in the foraging niche of wandering albatrosses: its relevance at an individual level
Filipe Ceia, Richard Phillips, Jaime Ramos, Yves Cherel, Rui Vieira, Pierre Richard and José Xavier
|According to optimal foraging theory, animals should distribute themselves to maximize their foraging efficiency, but their foraging strategies can differ at an individual level and vary according to factors such as sex, age, morphology and individual specialization (Bolnick et al. 2003, Weimerskirch 2007). Such differences may have implications for susceptibility to anthropogenic threats (e.g. interactions with fisheries; Xavier et al. 2004). In this study we tested short- and long-term consistency in the foraging niche in terms of habitat use, trophic level and, by inference, prey selection of the wandering albatrosses Diomedea exulans, a generalist predator. GPS tracking, diet and stable isotope analyses from blood (plasma and cells) and feathers from breeding wandering albatrosses at Bird Island (South Georgia) showed that there is a consistent sexual segregation between males and females in terms of foraging habitat during the non-breeding period (with females feeding more in northern waters). A total of 14% of the wandering albatrosses were considered fish specialists, 11% squid specialists and 74 % were generalists. However, approximately 40% of the birds showed consistency in diet consumed. As there was no relationship between foraging consistency and by mass index, specialists and generalists may have similar levels of body conditions. However, with females exploring more northern waters (Xavier et al. 2004; this study), female wandering albatrosses breeding at Bird Island might be more at risk with interactions with fisheries vessels (particularly longliners) from longline fisheries in Antarctic waters (around South Georgia) but also in sub-Antarctic waters, in oceanic waters and at the Patagonian shelf.||
This project forms part of a joint venture between the Institute of Marine Research (IMAR-CMA) of the University of Coimbra (Portugal) and the British Antarctic Survey (BAS, UK). Various stages of the project were co-funded by the Foundation for Science and Technology (Portugal), Centre D´Etudes Biologiques de Chizé (France) and the British Antarctic, within the BAS Ecosystems programme, the IMBER Integrating Climate and Ecosystem Dynamics in the Southern Ocean (ICED) regional programme and the Portuguese Polar Programme PROPOLAR.
Bolnick D. I., Svanbäck R., Fordyce J. A., Yang L. H., Davis J. M., Hulsey C. D., Forister M. L. (2003) The ecology of individuals: incidence and implications of individual specialization. The American Naturalist 161:1-28
Weimerskirch, H. (2007) Are seabirds foraging for unpredictable resources? Deep-Sea Research Part 2 Top Stud Oceanogr. 54: 211-223
Xavier, J. C., Trathan, P. N., Croxall, J. P., Wood, A. G., Podestá, G., Rodhouse, P. G. (2004) Foraging ecology and interactions with fisheries of wandering albatrosses (Diomedea exulans) breeding at South Georgia. Fisheries Oceanography 13: 324-344
DISCOVERY 2010: the past, present and future of a dynamic Southern Ocean region
British Antarctic Survey, Natural Environment Research Council, Madingley Rd, Cambridge, CB3 0ET, UK.
It is now 87 years since the inception of the Discovery expeditions that achieved an unparalleled series of biological and hydrological observations. The resulting Discovery Reports described in great detail what physical conditions and faunal communities existed within the Southern Ocean, providing a cornerstone for current Southern Ocean research. Present day scientific efforts have now moved on to the question of how such systems operate. The DISCOVERY 2010 programme was a large multidisciplinary effort undertaken to advance our understanding of one of the most dynamic Southern Ocean regions, the Scotia Sea.
The Scotia Sea ecosystem has different operational characteristics to other Southern Ocean regions. In contrast to the low primary productivity levels in much of the Southern Ocean, the Scotia Sea has large and long-lasting phytoplankton blooms. The high levels of primary productivity there support large populations of secondary producers, particularly calanoid copepods and Antarctic krill. The Scotia Sea and its fringing shelf systems contain nearly 30% of the total Southern Ocean population of Antarctic krill and this supports large populations of both land-based and pelagic predators at concentrations rarely encountered in other Southern Ocean regions.
Nevertheless, the Scotia Sea is not uniformly productive. For instance, whereas phytoplankton blooms in the South Georgia region can be sustained for 4–5 months, blooms are brief in October/November in other northern Scotia Sea regions. Further south, they are mainly constrained temporally and spatially to the ice-edge. Furthermore, large areas, especially in the western Scotia Sea, are more akin to the High Nutrient Low Chlorophyll (HNLC) status that dominates elsewhere in the Southern Ocean, mainly as a result of the limited availability of iron. Within its relatively small area therefore, the Scotia Sea presents the full range of productivity regimes found throughout the wider Southern Ocean.
Parts of the Scotia Sea are also experiencing rapid change. Within the northern Scotia Sea, and specifically around South Georgia, Whitehouse et al. (2008) reported a seasonally averaged increase of 1.5°C over the top 100 m of the water column over the past 80 years, with a 0.9°C warming in January and 2.3 °C warming in August. This warming has been accompanied by changes in sea-ice patterns, with the mean duration of winter sea-ice across the Scotia Sea/Antarctic Peninsula regions reducing over the last 25 years.
The DISCOVERY 2010 programme carried out a series of three cruises in the spring, summer and autumn of consecutive years, undertaking many of the same measurements at the same locations in each year. The cruises followed a transect line from east of the South Orkneys to west of South Georgia (Fig. 11). Further sampling was carried out north of the transect line, at and around the location of the Polar Front. The sampling design was aimed at capturing both spatial and seasonal features of the Scotia Sea environment, so as to resolve the main drivers of this system.
Measurements of the air-sea CO2 fluxes and DIC deficits revealed the bloom downstream of South Georgia was a strong winter source and strong summer sink of atmospheric CO2 (Jones et al. 2012). Its DIC deficit was 4.6 mol m-2, slightly larger than that of the Kerguelen bloom. However its larger area meant a total DIC deficit of 4.4 x 1012 g C, almost double that for the bloom found at the Kerguelen islands in the Southern Ocean Indian sector. The great size, intensity and longevity of the iron fertilised South Georgia bloom thus made it the site of the strongest seasonal carbon uptake in the ice-free zone of the Southern Ocean (Fig. 12).
In terms of export of carbon to depth, Korb et al. (2012) found that two major determining factors, algal size and species composition, were substantially different across the Scotia Sea. The impact of these differences was resolved by sediment traps at 2000 m. The region downstream of South Georgia, with larger, more silicified diatoms, contained levels of sedimentary carbon that were over 10-fold of those found in the upstream traps, where such diatoms were less prevalent (Whitehouse et al. 2012). Atkinson et al. (2012) also found that krill feeding on large, more silicified diatoms were more likely to produce rapidly sinking faecal pellets, so increasing rates of export.
The above average change in upper water column temperature and shortening sea ice season is placing additional stress on the prevailing Scotia Sea community. DISCOVERY 2010 considered the response to change from several different angles, in terms of how the pelagic community is structured (Tarling et al., 2012; Ward et al., 2012), how the foodweb is organised (Hill et al., 2012; Stowasser et al., 2012) and what historical patterns can tell us about the modern day situation (Mackey et al., 2012). In particular, Mackey et al. (2012) showed that distributions of many key species have probably already changed since the original Discovery expeditions as a result of the rise in temperature (Fig. 13). One of the main consequences of change is likely to be the regional extinction of some species and the introduction of others, an effect that will be seen first as changes in relative abundance patterns, but may lead to different levels of consumption, secondary production and nutrient recycling and, ultimately, a shift in higher-predator numbers. DISCOVERY 2010 has furthered our ability to consider such scenarios of change and the consequences these have for the wider ecosystem.
The heterogeneity of the Scotia Sea was further resolved through identifying bioregions. A bioregion is an area of similar physical and biological characteristics within which there is a common mode of biological operation. Defining bioregions is particularly useful in a comparative sense since they help identify how the operation of one region differs from another. Ward et al. (2012) used physical, biogeochemical and taxonomic information from spring, summer and autumn to produce the most definitive bioregionalisation of the Scotia Sea yet achieved. They found a primary regionalisation that was based on two groups of stations, the boundary lying within the frontal envelope of the South Antarctic Circumpolar Current Front (SACCF), which is also broadly coincident with the position of the maximum extent of the ice influence in this part of the Scotia Sea. This pattern was repeated between years and also appeared to be consistent across a range of trophic levels.
A major feature of the bioregion to the south of the SACCF was the dominance of Antarctic krill biomass (Fig. 13). A long lasting paradigm has been that the Southern Ocean food web is simple, being dominated by Antarctic krill that form an efficient link from primary production to allow a large biomass of krill-dependent predators. This paradigm has been questioned as a wealth of more recent literature has highlighted the important role of the microbial foodweb, and small copepods that typify oceans worldwide. The work of the DISCOVERY 2010 programme reaffirms that, at least in the southern Scotia Sea, the short krill-dominated food chain is of greater importance.
While krill is prominent in the southern Scotia Sea foodweb, Ward et al. (2012) emphasised the key role of copepods in energy transfer via longer food chains in the northern region. This was also shown by Stowasser et al. (2012) and Tarling et al. (2012), who found that myctophid-fish occupied higher trophic levels in the copepod-dominated northern area, particularly in autumn when krill were scarcer. Therefore in the northern area, in poor krill years and also in autumn, there may be an increase in food chain length involving small copepods and much higher abundance of their invertebrate consumers such as Themisto gaudichaudii which, in turn, are eaten by the myctophids.
The above average change in upper water column temperature and shortening sea ice season is placing additional stress on the prevailing Scotia Sea community. DISCOVERY 2010 considered the response to change from several different angles, in terms of how the pelagic community is structured (Tarling et al., 2012; Ward et al., 2012), how the foodweb is organised (Hill et al., 2012; Stowasser et al., 2012) and what historical patterns can tell us about the modern day situation (Mackey et al., 2012). In particular, Mackey et al. (2012) showed that distributions of many key species have probably already changed since the original Discovery expeditions as a result of the rise in temperature (Fig. 14). One of the main consequences of change is likely to be the regional extinction of some species and the introduction of others, an effect that will be seen first as changes in relative abundance patterns, but may lead to different levels of consumption, secondary production and nutrient recycling and, ultimately, a shift in higher-predator numbers. DISCOVERY 2010 has furthered our ability to consider such scenarios of change and the consequences these have for the wider ecosystem.
A special issue of work generated by the DISCOVERY 2010 programme has been published in Deep-Sea Research II, volume 59-60 (2012) entitled “DISCOVERY 2010: Spatial and temporal variability in a dynamic polar ecosystem” edited by Geraint Tarling, Peter Ward, Angus Atkinson, Martin Collins and Eugene Murphy.
Atkinson, A., Schmidt, K., Fielding, S., Kawaguchi, S., Geissler, P.A., 2012. Variable food absorption by Antarctic krill: relationships between diet, egestion rate and the composition and sinking rates of their fecal pellets. Deep-Sea Res. II 59–60, 147–158.
Hill, S.L., Keeble, K., Atkinson, A., Murphy, E.J., 2012. A foodweb model to explore uncertainties in the South Georgia shelf pelagic system. Deep-Sea Res. II 59–60, 237–252.
Jones, E.M., Bakker, D.C.E., Venables, H.J., Watson, A.J., 2012. Dynamic seasonal cycling of inorganic carbon downstream of South Georgia, Southern Ocean. Deep-Sea Res. II 59–60, 25–35.
Korb, R.E., Whitehouse, M.J., Ward, P., Gordon, M., Venables, H.J., Poulton, A.J., 2012. Regional and seasonal differences in microplankton biomass, productivity and structure across the Scotia Sea: implications for the export of biogenic carbon. Deep-Sea Res. II 59–60, 67–77.
Mackey, A.P., Atkinson, A., Hill, S.L., Ward, P., Cunningham, N.J., Johnston, N.M., Murphy, E.J., 2012. Antarctic macrozooplankton of the southwest Atlantic sector and Bellingshausen Sea: baseline historical distributions (Discovery Investigations, 1928–1935) related to temperature and food, with projections for subsequent ocean warming. Deep-Sea Res. II 59–60, 130–146.
Stowasser, G., Atkinson, A., McGill, R.A.R., Phillips, R.A., Collins, M.A., Pond, D.W., 2012. Food web dynamics in the Scotia Sea in summer: a stable isotope study. Deep-Sea Res. II 59–60, 208–221.
Tarling, G.A., Stowasser, G., Ward, P., Poulton, A.J., Zhou, M., Venables, H.J., McGill, R.A.R., Murphy, E.J., 2012. Seasonal trophic structure of the Scotia Sea pelagic ecosystem considered through biomass spectra and stable isotope analysis. Deep-Sea Res. II 59–60, 222–236.
Ward, P., Atkinson, A., Venables, H.J., Tarling, G.A., Whitehouse, M.J., Fielding, S., Collins, M.A., Korb, R.E., Black, A., Stowasser, G., Schmidt, K., Thorpe, S.E., Enderlein, P., 2012b. Food web structure and bioregions in the Scotia Sea: a seasonal synthesis. Deep-Sea Res. II 59, 253–266.
Whitehouse, M.J., Meredith, M.P., Rothery, P., Atkinson, A., Ward, P., Korb, R.E., 2008. Rapid warming of the ocean around South Georgia, Southern Ocean, during the 20th century: forcings, characteristics and implications for lower trophic levels. Deep-Sea Res. I 55, 1218–1228.
Whitehouse, M.J., Atkinson, A., Korb, R.E., Venables, H.J., Pond, D.W., Gordon, M., 2012. Substantial primary production in the land-remote region of the central and northern Scotia Sea. Deep-Sea Res. II 59–60, 47–56.
ICED Southern Ocean Sentinel and benchmarking Southern Ocean ecosystems beginning in 2020
A. Constable1, 2, A. Press2
1 Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050 Australia
2 Antarctic Climate and Ecosystem Cooperative Research Centre, Private Bag 80, Hobart Tasmania 7001, Australia
Southern Ocean ecosystems have been changing since the near extirpation of seals starting in the 1800s and the overexploitation of many whale species and benthic finfish in the mid-20th century (Koch et al. 2007). Since the late 1960s, significant changes to Southern Ocean properties, probably resulting from the depletion of ozone over the Antarctic, have been observed including increased westerly winds (Turner et al. 2009a) as well as a southward shift in the Southern Annular Mode (Turner et al. 2009b), the extent and timing of sea ice advance and retreat, (although varying greatly from positive to negative regionally, Turner et al. 2009a; Stammerjohn et al. 2008); abrupt loss of ice shelves (Cook et al. 2005, 2010); freshening of Antarctic Bottom Water and surface waters near the continent, a southward shift in the Antarctic Circumpolar Current fronts, along with a changed eddy field (Meredith & Hogg 2006; Sallee et al. 2009; Sokolov & Rintoul 2009). Increased CO2 in the atmosphere has also led to a decrease in ocean pH (Turner et al. 2009b). The Southern Ocean is expected to change substantially in coming decades as a result of climate change and ocean acidification (Turner et al. 2009b).
In recent decades, changes in biota have been identified but the mechanisms of change are poorly understood. Pelagic species including zooplankton (Hunt & Hosie 2005) may migrate southward as the ocean warms, but regional geography and oceanography may make the response more complex (Trathan & Agnew 2010). In the Scotia Sea, a decline in density of Antarctic krill, the best studied Southern Ocean pelagic species, has been attributed to a decline in sea ice (Atkinson et al. 2004). The switch from a krill-based food web to a copepod- and fish-based food web in times of low krill abundance (Murphy et al. 2007; Waluda et al. 2010) suggests that the latter may become more common in the future (Trathan et al. 2007; Shreeve et al. 2009). The prognosis for Antarctic krill overall is ambiguous as factors that could impact directly on krill vary regionally, and because they are able to adapt physiologically and behaviourally (Schmidt et al. 2011). New research also shows that larval krill survival may be negatively affected by increasing ocean acidity (Kawaguchi et al. 2011) adding further complexity to these assessments.
Some key trends in distribution and abundance of bird populations (penguins and flying birds) have been linked to recent change (e.g. Trathan et al. 2007; Barbraud & Weimerskirch 2001; Forcada et al. 2005; Jenouvrier et al. 2005). However, the ecological pathways of impacts on marine mammals and birds may be difficult to determine because higher predator populations are less sensitive to small-scale spatial and temporal variability of lower trophic levels, e.g. the contrasting changes in Adelie and other penguin populations (Trivelpiece et al. 2011; Smith et al. 2011; Nicol & Raymond 2011).
Why good estimates of change are needed
A great difficulty in interpreting the cause of these changes is the absence of integrated measurements of a suite of variables across the range of physical and biological properties of the ecosystems. Moreover, attention needs to be given to estimating how regional differences and intra- and inter-annual variability may impact on using these indicators for assessing long-term trends in the ecosystems (Constable 2002, 2006, 2011).
Future impacts of climate change on marine ecosystems are being predicted using a combination of expert views and simulation models (Hitz & Smith 2004; Sarmiento et al. 2004). Predictions to date have focussed on shifts in distribution and abundance of biological populations in marine systems driven by temperature (Harley et al. 2006). However, both abiotic and biotic changes and responses are expected to be significantly more complex. For example, survival and condition of many organisms may be more affected by changes in ocean chemistry or by disruptions to food web dynamics than by changes in temperature (Harley et al. 2006; Clarke et al. 2007).
Observations are needed to unambiguously validate the conclusions from modelling and forecasting studies. Such a program is essential for appropriately setting both ecosystem-based catch limits for krill and finfish species in the region (SC-CAMLR, 2011) and conservation requirements for threatened, endangered or recovering species, such as whales and albatross.
The value of estimating status and trends of Southern Ocean marine ecosystems
Despite the historical changes to the ecosystem, the Southern Ocean remains the easiest region to separate the ecosystem impacts of climate change and ocean acidification from direct anthropogenic effects - many other regions have continuing and confounding effects of pollution, catchment and coastal zone modification and fisheries (Constable & Doust 2009). A monitoring and assessment program in the Southern Ocean would play an important role in evaluating and estimating the magnitudes and rates of change in global marine ecosystems, testing predictions from climate model scenarios of the Intergovernmental Panel on Climate Change (IPCC) (IPCC, 2001; Meehl et al. 2007; Rosenzweig et al. 2007) and, thereby, provide a sound basis for signalling future changes in ecosystems in the Southern Ocean and beyond. This is fundamental to achieving ecologically sustainable Antarctic krill fisheries and the conservation of Antarctic marine life as a whole.
The challenge is to develop a systematic, robust and cost-effective field and analytical methodology for assessing the status and trends of Southern Ocean marine ecosystems.
The Southern Ocean Sentinel, hereafter the Sentinel, is a project of the IMBER regional programme Integrating Climate and Ecosystem Dynamics in the Southern Ocean (ICED). It aims to develop an internationally integrated programme to estimate climate change impacts on Southern Ocean ecosystems. Impacts on the physical environment of climate change are expected to differ between regions in the Southern Ocean. With studies synchronised between regions, this provides an opportunity, a natural experiment, to test hypotheses about direct and indirect ecosystem responses to changing physical environments. The Sentinel aims to build on the experience of the World Ocean Circulation Experiment (WOCE), Global Ocean Ecosystem Dynamics (GLOBEC), and the International Polar Year (IPY) to facilitate simultaneous benchmarking of regional ecosystems in order to standardise regional measurements in a circumpolar assessment of ecosystem change.
A second workshop on the Sentinel in Hobart, Australia in May 2012 agreed on a work plan (Table 1) that would lead to a consolidated proposal on how to benchmark the overall status of Southern Ocean ecosystems with an international collaborative field program, in conjunction with the Southern Ocean Observing System, to begin benchmarking these ecosystems as a whole in 2020.
Benchmarking and measuring change in Southern Ocean ecosystems
The state of Southern Ocean ecosystems is mostly derived from integrated studies in a few locations on the Antarctic Peninsula and South Georgia, combined with the benchmarking of the state of krill from the CCAMLR (2000) survey in the Atlantic Sector (Watkins et al. 2004), and the BROKE (1996, Nicol et al. 2000) and BROKE West (2006, Nicol et al. 2010) surveys in East Antarctica. At present, large scale monitoring programs for assessing the current and future impacts of climate change on marine biodiversity and ecosystems are poorly developed. Internationally, the importance for larger scale measurement programs is now recognised (Hofmann 2009), particularly through the SCAR-SCOR Southern Ocean Observing System (SOOS, Rintoul et al. 2011) and ICED (Murphy et al. 2008). The Southern Ocean Sentinel (Constable & Doust 2009) aims to fulfil a key ICED milestone to establish long-term measurements of the state of ecosystems in the region. A set of meridional transects are being considered for this purpose, similar to the oceanographic approach established for by the WOCE, while accounting for the biological variation in productivity and food webs (Murphy et al. 2012, Fig.15). Existing data sets will be used to assess regional changes as far as possible and to help design a whole-of-Southern Ocean assessment.
For the whole-of-Southern Ocean assessment, measurements of a suite of indicator taxa and environmental variables need to be taken using a spatial and temporal sampling design that can disentangle potentially confounding drivers of change. The design is expected to include regular measurements on specified transects combined with land-based monitoring of predator activities. Integrated ecological studies would be undertaken in areas suitable for verifying the ecological signals arising from change in the indicators (Fig. 16).
Table 1: Work plan agreed at the second Sentinel Workshop. This is being developed into a scoping paper.
Atkinson, A. et al. (2004) Long-term decline in krill stock and increase in salps within the Southern Ocean. Nature 2996: 1-4.
Barbraud, C., Weimerskirch, H. (2001) Emperor penguins and climate change. Nature 411: 183-186.
Clarke, A. et al. (2007) Climate change and the marine ecosystem of the western Antarctic Peninsula. Phil. Trans. Royal Soc. B-Biol. Sci. 362: 149-166.
Constable, A. (2002) CCAMLR ecosystem monitoring and management: future work. CCAMLR Science 9: 233-253.
Constable, A. (2006) Setting management goals using information from predators. In: Boyd et al., editors. Top predators in marine ecosystems. Cambridge: Cambridge University Press. pp. 324-346.
Constable, A. (2011) Lessons from CCAMLR on the implementation of the ecosystem approach to managing fisheries. Fish and Fisheries DOI: 10.1111/j.1467-2979.2011.00410.x.
Constable, A., Doust, S. (2009) Southern Ocean Sentinel - an international program to asses climate change impacts on marine ecosystems: report of an international workshop, Hobart, April 2009: ACE CRC, Commonwealth of Australia & WWF-Australia. 81 pp. p.
Cook, A. et al. (2005) Retreating glacier fronts on the Antarctic Peninsula over the past half century. Science 308: 541–544.
Cook, A. et al. (2010) Overview of areal changes of the ice shelves on the Antarctic Peninsula over the past 50 years. Cryosphere 4: 77-98.
Forcada, J. et al. (2005) The effects of global climate variability in pup production of Antarctic fur seals. Ecology 86: 2408-2417.
Harley, C. et al. (2006) The impacts of climate change in coastal marine systems Ecology Letters 9: 228-241.
Hitz, S., Smith, J. (2004) Estimating global impacts from climate change. Global Environmental Change-Human and Policy Dimensions 14: 201-218.
Hofmann, E. (2009) Southern Ocean GLOBEC Research and the Future. Antarctic Science 21: 411-411.
Hunt, B., Hosie, G. (2005) Zonal structure of zooplankton communities in the Southern Ocean South of Australia: results from a 2150 km continuous plankton recorder transect. Deep-Sea Research Part I 52: 1241-1271.
IPCC (2001) Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the IPCC; Houghton et al., editors. Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press.
Jenouvrier, S. et al. (2005) Evidence of a shift in the cyclicity of Antarctic seabird dynamics linked to climate. Proc. Royal Soc. Lond. Series B-Biol. Sci. 272: 887-895.
Kawaguchi, S. et al. (2011) Will krill fare well under Southern Ocean acidification? Biology Letters 7: 288-291.
Kock, K-H, et al. (2007) Fisheries in the Southern Ocean: an ecosystem approach. Phil. Trans. Royal Soc. B-Biol. Sci. 362: 2333-2349.
Meehl G., et al. (2007) Global Climate Projections. In: Solomon S et al., editors. Climate Change 2007: The Physical Science Basis Contribution of Working Group I to the Fourth Assessment Report of the IPCC. Cambridge, UK & New York, USA.: Cambridge University Press.
Meredith, M., Hogg, A. (2006) Circumpolar response of Southern Ocean eddy activity to a change in the Southern Annular Mode. Geophysical Research Letters 33: doi:10.1029/2006GL026499.
Murphy, E. et al. (2007) Spatial and temporal operation of the Scotia Sea ecosystem: a review of large-scale links in a krill centred food web. Phil. Trans. Royal Soc. B-Biol. Sci. 362: 113-148.
Murphy, E. et al. (2008) Integrating Climate and Ecosystem Dynamics in the Southern Ocean - a Circumpolar Ecosystem Program: Science Plan and Implementation Strategy.
Murphy, E. et al. (2012) Developing integrated models of Southern Ocean food webs: Including ecological complexity, accounting for uncertainty and the importance of scale. Progress in Oceanography 102:74-92.
Nicol, S. et al. (2000) "BROKE" a biological / oceanographic survey off the coast of East Antarctica (80-150E) carried out in January-March 1996. Deep-Sea Research II: 2281-2298.
Nicol, S. et al. (2010) BROKE-West, a large ecosystem survey of the South West Indian Ocean sector of the Southern Ocean, 30E–80E (CCAMLR Division 58.4.2). Deep-Sea Research II 57: 693-700.
Nicol, S., Raymond, B. (2011) Pelagic ecosystems in the waters off East Antarctica (30°E–150°E). In: Rogers et al., editors. Antarctic ecosystems: an extreme environment in a changing world. London: J. Wiley and Sons. pp. in press.
Rintoul, S. et al. (2011) The Southern Ocean Observing System: initial science and implementation strategy. Cambridge, UK: SCAR-SCOR.
Rosenzweig C, et al. (2007) Assessment of observed changes and responses in natural and managed systems. In: Parry M et al., editors. Climate Change 2007: Impacts, Adaptation and Vulnerability Contribution of Working Group II to the Fourth Assessment Report of the IPCC. Cambridge, UK: Cambridge University Press. pp. 79-131.
Sallee, J. et al. (2009) Response of the Southern Ocean mixed-layer depth to climate variability. J. Geophysical Research.
Sarmiento, J. et al. (2004) Response of ocean ecosystems to climate warming. Global Biogeochemical Cycles 18.
SC-CAMLR (2011) Report of the thirtieth meeting of the Scientific Committee for the Conservation of Antarctic Marine Living Resources (SC-CAMLR XXX). Hobart, Australia: CCAMLR.
Schmidt, K. et al. (2011) Seabed foraging by Antarctic krill: Implications for stock assessment, bentho-pelagic coupling, and the vertical transfer of iron. Limnology and Oceanography 56 1411–1428.
Shreeve, R. et al. (2009) Feeding ecology of myctophid fishes in the northern Scotia Sea. Marine Ecology-Progress Series 386: 221-236.
Smith Jr., W. et al. (2011) The Ross Sea Continental Shelf: regional biogeochemical cycles, trophic interactions, and potential future changes. In: Rogers et al., editors. Antarctic ecosystems: an extreme environment in a changing world. London: J. Wiley and Sons. pp. in press.
Sokolov, S., Rintoul, S. (2009) The circumpolar structure and distribution of the Antarctic Circumpolar Current fronts. Part 2: Variability and relationship to sea surface height. J. Geophysical Research 114: doi:10.1029/2008JC005248.
Stammerjohn, S. et al. (2008) Trends in Antarctic annual sea ice retreat and advance and their relation to El Nino–Southern Oscillation and Southern Annular Mode variability. J. Geophysical Research 113: CO3S90.
Trathan, P. et al. (2007) Environmental forcing and Southern Ocean marine predator populations: effects of climate change and variability. Phil. Trans. Royal Soc. B-Biol. Sci. 362: 2351-2365.
Trathan, P., Agnew, D. (2010) Climate change and the Antarctic marine ecosystem: an essay on management implications. Antarctic Science 22: 387-398.
Trivelpiece, W. et al. (2011) Variability in krill biomass links harvesting and climate warming to penguin population changes in Antarctica. Proc. Nat. Acad. Sci. 108: 7625-7628.
Turner, J. et al. (2009a) Non-annular atmospheric circulation change induced by stratospheric ozone depletion and its role in the recent increase of Antarctic sea ice extent. Geophysical Research Letters 36: L08502.
Turner, J. et al. (eds) (2009b) Antarctic climate change and the environment. Cambridge UK: SCAR. 526 p.
Waluda, C. et al. (2010) Linking predator and prey behaviour: contrasts between Antarctic fur seals and macaroni penguins at South Georgia. Marine Biology 157: 99-112.
Watkins, J. et al. (2004) The CCAMLR 2000 Survey: a multinational, multi-ship biological oceanography survey of the Atlantic sector of the Southern Ocean. Deep Sea Research Part II 51: 1205-1213.
Impacts on the Deep-sea Ecosystem by a Severe Coastal Storm
First results of the DOSMARES project
Anna Sanchez-Vidal, Miquel Canals, Antoni M. Calafat, and the DOSMARES team
GRC Geociències Marines, Departament d’Estratigrafia, Paleontologia i Geociències Marines, Universitat de Barcelona, Campus de Pedralbes, Martí i Franquès s/n, 08028 Barcelona, Spain
The main objective of the IMBER-endorsed project DOSMARES (Deep-water submarine canyons and slopes in the Mediterranean and Cantabrian Seas: from synchrony of external forcings to living resources) is twofold. First, to understand the effects of the atmospheric teleconnections between the Cantabrian and the north-western Mediterranean Seas, and the impacts of these on the pelagic and benthic deep ocean ecosystem. Second, to determine how the transfer of the signal from the external forcings controls the community structure and population dynamics of the deep ocean. The effect of external forcings on the transfer of matter and energy to the deep ocean ecosystem is investigated simultaneously in the two areas, using historical environmental (atmospheric, oceanographic and river discharge) data analysis, in conjunction with an annual cycle of hydro-sedimentary dynamics measurements and sampling. Historical fisheries data (catches and landings) and pelagic, benthopelagic and benthonic sampling of meio-, macro- and megafauna are also used.
Major coastal storms, associated with strong winds, high waves, intensified currents, and sometimes, heavy rain and flash floods, receive attention because of the serious damage they cause along the shoreline and the threats they pose to navigation. However, there is a profound lack of knowledge of the deep-sea impacts of severe coastal storms. Efforts to understand the implications of extreme weather perturbations on deep-sea environments have been hampered by the lack of concurrent measurements of key parameters such as near bottom flows or sediment characteristics. In a recent paper published in the journal PLoS ONE, scientists from the DOSMARES project demonstrated how the effects of an atmospheric forcing (i.e. coastal storms) extend very rapidly to the deep-sea environment. This paper generated considerable interest in the media (See Science Magazine “Big storms roil even the deep”, 1 February 2012).
The storm hit the Catalan coast (Fig. 17) on 26 December 2008, with eastern winds of up to 20ms-1, wave height in excess of 14m, wave periods up to 14s and a return period of more than 100 years. The high waves and strong current induced shear stress on the sea floor that caused large amounts of shelf sediments to move, abrading and burying benthic communities (Fig. 18). On rocky substrates, algal cover, sea urchins and colonies of long-lived gorgonians were virtually wiped out by abrasion. In sandy substrates, Posidonia oceanica seagrass beds were either deeply buried or unearthed and uprooted. The storm mobilized and dropped large volumes of sand and carbonate debris onto the upper reaches of the head of the Blanes submarine canyon (Fig. 19). In addition it caused the remobilization of a shallow-water reservoir of marine organic carbon (more than 5.5 tonnes of particulate organic carbon) associated with fine particles that were redistributed across the deep basin (Fig. 19).
This research demonstrated that in spite of their catastrophic effects on coastal communities (or rather, because of these), high magnitude storms contribute significantly to maintaining the deep ecosystem through the episodic supply of large volumes of organic carbon mostly along submarine canyons. This adds a new perspective to current understanding of the impacts that atmospheric-driven phenomena may have on deep-sea ecosystems, and consequently, on their living resources.
Sanchez-Vidal A, Canals M, Calafat AM, Lastras G, Pedrosa-Pàmies R, Menéndez M, Medina R, Company JB, Hereu B, Romero J, Alcoverro T. (2012) Impacts on the Deep-Sea Ecosystem by a Severe Coastal Storm. PLoS ONE 7(1): e30395. doi:10.1371/journal.pone.0030395
New to IMBER!
IMBER is delighted to welcome Irene Utne as the new Administrative Assistant at the IPO in Bergen, Norway.
She can be reached at: email@example.com
Two new IMBER endorsed projects: MERMEX and AMT
MERMEX: Marine Ecosystems Response in the Mediterranean Experiment
MerMex focuses on understanding the effects of key natural and anthropogenic forcings on marine ecosystems and organisms in Mediterranean Sea.
During the next five years, MERMEX will investigate:
- How changes in stratification and destratification mechanisms, and in the overall thermohaline circulation, will alter the spatio-temporal distribution of nutrients and their budgets.
- How likely changes in nutrient input will affect nutrient availability in the photic layer of the Mediterranean Sea, and consequently the relative abundance of primary producers and higher trophic levels.
- The sources and sinks of chemical contaminants (e.g., atmosphere versus rivers) and seasonal variations.
- The role of the land-sea boundary (rivers, large cities, groundwater discharge) in the material balance of the Mediterranean Sea (carbon, nutrient, contaminants).
- Whether changes in the frequency or magnitude of extreme events lead to the dispersion or dilution of carbon, nutrients and pollutants or, result in their accumulation in specific compartments.
- The actual rate of change of temperature, pH and light radiation in the Mediterranean Sea and the effect of these on the functioning of pelagic and benthic Mediterranean ecosystems.
- Whether, as a result of surface seawater warming, nanophytoplankton and jellyfish will come to dominate the planktonic community of the pelagic ecosystem, as suggested by several recent studies?
AMT: Atlantic Meridional Transect
The Atlantic Meridional Transect (AMT) programme undertakes biological, chemical and physical oceanographic research during an annual cruise between the UK and destinations in the South Atlantic. The transect crosses ecosystems ranging from sub-polar to tropical and from euphotic shelf seas and upwelling systems to oligotrophic mid-ocean gyres. AMT is the longest running Atlantic Ocean-based programme that makes repeat measurements of core parameters and informs on trends and variability in biodiversity and function of the Atlantic ecosystem. It has provided an in-situ observation system for the Atlantic Ocean between ~50°N and ~50°S since 1995 and the longest time series of data on basin scales. This unique spatially extensive decadal dataset continues to be deposited and made available to the wider community through the British Oceanographic Data Centre (http://www.bodc.ac.uk/projects/uk/amt/). The programme is hosted by Plymouth Marine Laboratory (http://www.pml.ac.uk/) in collaboration with the National Oceanography Centre, Southampton (http://noc.ac.uk/) and provides an exceptional opportunity for nationally and internationally driven collaborative endeavours. An integral part of AMT is to provide a training arena for the next generation of oceanographers. This has recently been enhanced through the development of the POGO-AMT fellowship programme (http://ocean-partners.org/) which supports the participation of students or early career professionals from developing nations. Participants in this fellowship programme benefit from working alongside experienced researchers in the development of research skills, the formation of collaborative links and capacity building for their home institutes and countries.
IMBER future events
IMBIZO III (28-31 January 2013, Goa, India)
The future of marine biogeochemistry, ecosystems and societies.
Multi-dimensional approaches to the challenges of global change in continental margins and open ocean systems.
For more info, please visit IMBIZO lll website…
- Bonus Data Management workshop (27 January 2013)!
ESSAS Annual Science and SSC Meetings (7-11 January 2013, Hakodate, Japan)
The theme of the meeting is Spatial Dynamics of Subarctic Marine Ecosystems.
- Abstracts will be accepted until December 10, 2012. Please follow the abstract format posted on the ESSAS website
- For more info, please visit http://www.imr.no/essas/en
The 2nd CLIOTOP Symposium (11-15 February 2013, Noumea, New Caledonia)
- Additional two-day course on The Analysis of Predator Diet and Stable Isotope Data (9 and 10 February)
- Includes: introduction to R and an overview of new diet and isotope analysis methodology and a tutorial of the diet package in R.
- You will be able to analyse your own data, with guidance from the course leaders.
- Only 30 participants can be accommodated - book now to avoid disappointment!
IMBER endorsed events
MAREMIP/ EUR-OCEANS/ IMBER/ GREENCYCLES II Workshop: Impact of climate change on marine ecosystems
(4-6 March 2013, Paris, France)
The programme is structured around the following themes:
- Impact of climate change on marine ecosystems
- Hot topics in marine ecosystem modelling
- Future directions
IMBER special session at the 11th INTECOL Congress
Predicting and protecting marine biodiversity and ecosystem function in a high CO2 world
18-23 August 2013, London
Conveners: Steve Widdicombe, Jim Barry and Jean-Pierre Gattuso
The theme of the congress is Advancing Ecology and Making it Count, and it is part of the centenary celebrations of the British Ecological Society.
Abstract submission system is open at http://www.intecol2013.org/27_Callforabstracts.html
For more information, go to: http://www.intecol2013.org/index.php
Early Career scientist opportunities
List of acronyms
CLIOTOP: CLimate Impacts on Oceanic Top Predators
CODATA: Committee on Data for Science and Technology
ECNU: East China Normal University
ESSAS: Ecosystem Studies of Sub-Arctic Seas
ICSU: International Council for Science
IOCAS: Institute of Oceanology, Chinese Academy of Sciences
IPO: International Project Office
IPY: International Polar Year
IRDR: Integrated Research on Disaster Risks
SKLEC: State Key Laboratory of Estuarine and Coastal Research
Should you wish to contribute an article for the IMBER Update, please contact Lisa Maddison
Published by IMBER
Editors: IMBER IPO