Ecological-network models link diversity, structure and function in the plankton food-web.

Area of Science:

• Marine ecology
• Oceanography
• Ecosystem modeling

Background:

• Plankton communities exhibit significant diversity in functional groups, including autotrophs, mixotrophs, and heterotrophs.
• Understanding plankton food web dynamics is crucial for comprehending marine ecosystem functioning and carbon cycling.

Purpose of the Study:

• To develop and analyze a comprehensive planktonic food-web model.
• To investigate how plankton community structure and function differ between bloom ('green') and non-bloom ('blue') states.
• To assess the impact of these changes on trophic interactions and energy transfer efficiency.

Main Methods:

• Development of a 63-node planktonic food-web model incorporating diverse functional groups.
• Implementation of the model in two variants representing contrasting phytoplankton biomass levels (bloom vs. non-bloom).
• Analysis of taxonomically disaggregated food webs to identify shifts in trophic behavior and carbon fluxes.

Main Results:

• Distinct food web organizations and carbon flux patterns were observed between the 'green' and 'blue' states.
• Selective grazing by metazoan and protozoan consumers drove significant re-organization of the food web.
• A seven-fold decrease in phytoplankton biomass resulted in only a two-fold decrease in potential planktivorous fish biomass, indicating resilience.

Conclusions:

• Plankton communities exhibit 'adaptive' responses to environmental perturbations through internal mechanisms and species-specific functionalities.
• Food web structure and function are tightly linked, with shifts in trophic roles mediating ecosystem responses.
• The model highlights the importance of considering trophic diversity and interactions in understanding marine ecosystem dynamics.