Optimal Productivity in Aquatic Ecosystems: Theoretical Insights and Observations from the Littoral Zone of Lake Tanganyika

Document Type

Presentation

Publication Date

2-2011

Abstract

Optimal Productivity in Aquatic Ecosystems: Theoretical Insights and Observations from the Littoral Zone of Lake Tanganyika great tropical lakes of the world, offers opportunities to untangle the biological and physical processes that give rise to low-nutrient, high-productivity ecosystems. We have developed theoretical models of nutrient cycling in the littoral zone to clarify the mechanisms for maintaining high primary production in the face of intensive grazing and fluctuating nutrient inputs. After parameterizing these models using field data, we find that the form of the functional relationships between consumers and their resources, the frequency of nutrient inputs from upwelling, and the presence of both benthic and planktonic food chains are all essential for understanding the productivity of this ecosystem. These theoretical results accord well with field results, which indicate that phytoplankton respond more strongly to upwelling than benthic producers, and grazing fishes may actually enhance littoral productivity by retaining and recycling nutrients. These results provide evidence for the grazing optimization hypothesis, and suggest that climate warming and fishing will strongly affect the functioning of this unique ecosystem.

Comments

Presented at the Aquatic Sciences Meeting, San Juan, Puerto Rico.


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