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Theme 1

Interactions Between Biogeochemical Cycles and Marine Food Webs

What are the key marine biogeochemical cycles and related ecosystem processes that will be impacted by global change?


The inputs, losses, dynamics and chemical forms of macro- and micronutrients influence autotrophic and heterotrophic organisms in the ocean. These factors can impact metabolic rates and processes, population and community dynamics, and food web and community structures. The relationships between the life cycles of marine organisms and the distributions of macro- and micronutrients are reciprocal, and coupled on a wide range of space and time scales. Changes in microbial and phytoplankton activity can alter the composition, production and subsequent degradation of organic matter. Differential remineralisation may lead to decoupling of nutrient cycles within the water column. Comparisons of different systems provide new insights for identifying and understanding fundamental interactions between marine biogeochemical cycles and ecosystems.  

Understanding how the transformation and transport of elements involved in biogeochemical cycles relates to food web dynamics, is a major intellectual challenge for marine science and IMBER.

Key issues

Issue 1.1 Transformation of organic matter in marine food webs

  • What controls the stoichiometry and form of “bioreactive” elements in space and time?
  • What controls production, transformation, and breakdown of organic matter in marine food webs?

Issue 1.2 Transfers of matter across ocean interfaces

  • What are the time and space scales of remineralisation of organic matter in the mesopelagic layer?
  • How does nutrients exchange between continental margins and the ocean interior impact biogeochemical cycles?
  • How does exchange between the seafloor and the water column impact food web structure and function

Issue 1.3 Material flows in end-to-end food webs

  • How do food web dynamics affect nutrient availability?
  • How do key functional groups, species, and genes affect biogeochemical cycles?
  • How do species biodiversity and species interactions affect food web functioning and biogeochemical cycling?
  • How are the interactions between biogeochemical processes and food webs recorded in palaeo-proxies?