Brett, M.T., D. Muller-Navarra
Abstract:
The marine and freshwater plankton literature suggests essential fatty acids (EFA) are abundant in the high food-quality algae and rare in low food-quality algae. EFAs are also strongly attenuated in trophic transfer through planktonic food-webs. That is they are much more concentrated in phytoplankton, who produce them, than in herbivorous zooplankton or zooplanktivorous fish, who do not produce them. Recent research has shown a very strong correlation between the eicosapentaenoic acid content of natural phytoplankton communities and herbivorous zooplankton production. Planktonic food-webs with high EFA phytoplankton have very high zooplankton to phytoplankton biomass ratios, while systems with low EFA phytoplankton have relatively speaking quite low zooplankton biomass. In addition, the seasonal succession of zooplankton and phytoplankton in many temperate lakes follows patterns closely tied to phytoplankton EFA content. When phytoplankton have high EFA content, zooplankton graze the algae to low levels. However, when phytoplankton EFA content is low, the zooplankton are unable to control phytoplankton biomass. This research suggests EFAs may regulate energetic efficiency across the plant-animal interface, secondary production and the strength of trophic coupling in aquatic pelagic food-webs.
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