Interhabitat Transport of Nutrients by Detritivorous Fish: Impacts on Phytoplankton Communities

[9318452] Vanni这项研究旨在了解食性鱼类如何通过充当“营养泵”来影响湖泊浮游植物群落。这些鱼类以底栖动物碎屑为食，并将营养物质（氮和磷）排泄到沼泽栖息地，有效地将营养物质从底栖动物输送到沼泽栖息地，营养物质可以刺激浮游植物生长并改变浮游植物群落结构。动物可以以多种方式影响群落，众所周知，在北部湖泊中，鱼类可以通过食物链的相互作用对浮游植物群落产生强烈的影响。本文提出，在温水湖泊和水库中，鱼类主要通过营养泵机制影响浮游植物，而不是通过传统的食物链相互作用。具体目标是量化食性鱼类对湖泊浮游植物群落的群落水平影响。需要验证的假设包括：1)营养盐泵作用于浮游植物；2)营养盐泵作用与鱼类种群结构和碎屑养分含量有关；3)在水流低流入时期，营养盐泵作用是小型水库浮游植物的主要营养来源。这些假设将通过一系列的经验观察、实地和实验室实验进行检验。这项研究将提高我们对食物网调控、自上而下与自下而上对社区的控制以及底生态耦合的认识。虽然该项目侧重于社区效应，但它整合了从个人到生态系统的组织层面。此外，由于营养泵可能对蓝绿藻繁殖的频率和强度产生影响，因此该研究对水质管理具有启示意义。＊＊＊

9318452 Vanni This research seeks to understand how detritivorous fish affect lake phytoplankton communities by acting as "nutrient pumps." By feeding on benthic detritus and excreting nutrients (nitrogen and phosphorus) into the limnetic habitat, these fish effectively pump nutrients from benthic to limnetic habitats, where nutrients can stimulate phytoplankton growth and alter phytoplankton community structure. Animals can affect communities in many ways and it is well known that in northern lakes fish can have strong effects on phytoplankton communities through food chain interactions. It is proposed here that in warm-water lakes and reservoirs, fish affect phytoplankton primarily through the nutrient pump mechanism rather than through conventional food chain interactions. The specific objectives are to quantify the community level effects of detritivorous fish on lake phytoplankton communities. Hypotheses to be tested include: 1) detritivorous fish affect phytoplankton via the nutrient pump mechanism, 2) the effects of the nutrient pump mechanism is dependent on fish population structure, and detrital nutrient content, and 3) detritivorous fish are a major source of nutrients to phytoplankton in small reservoirs during times with stream inflows are low. These hypotheses will be tested using a series of empirical observations, field and laboratory experiments. %%% This research will advance our knowledge of food web regulation, top down versus bottom up controls on communities, and benthic-limnetic coupling. Although this project focuses on community effects, it integrates levels of organization from individual to ecosystem. In addition, because nutrient pumps may have effects on the frequency and intensity of nuisance blooms of blue-green algae, the research has implications for water quality management. ***