Dissertation Research: Algal and Zooplankton Community Responses to Piscivory: Mediation Through Alternate Planktivore Types

富营养化最明显的症状之一是浮游植物现存量很高。最近，研究人员假设，通过增加湖泊中食鱼性鱼类的密度，应该使食浮游鱼类的丰度下降，从而导致浮游动物生物量增加或物种组成改变，从而间接降低浮游植物的现存量。食鱼性鱼类可以摄取的最大猎物大小受到它们嘴巴大小的限制。由于几项研究表明，这种“张口限制”在影响食鱼者和猎物之间的相互作用方面可能非常重要，所以食鱼者对不同体型的猎物群体应该有不同的影响。这种不同的捕食可能反过来影响鱼类对浮游动物和浮游植物的级联营养效应的程度。实验室实验将检测食性大口黑鱼(Micropterus Salmoides)对两种浮游动物的捕食选择，这两种浮游动物在一般体型中代表极端：软鳍和浅体浮游生物(Pimephales Proelas)和蓝鳍(Lepomis Macchirus)，硬刺和深体浮游生物。一项使用20个实验池塘的长期池塘实验也将检验大口黑鱼和黑鱼、小黑鱼和大口黑鱼和蓝鳍金枪鱼的相互作用及其对浮游动物和浮游植物的级联影响。这些实验的结果将检验生态学理论，并在湖泊管理中具有直接的应用价值。

One of the most visible symptoms of eutrophication is high phytoplankton standing crop. Recently, investigators have hypothesized that by increasing piscivorous fish densities in lakes, planktivorous fish abundance should be made to decline, leading to higher zooplankton biomass or altered species composition and thus indirectly to lower phytoplankton standing crop. Piscivorous fish are limited in the maximum size of prey they can ingest by the dimensions of their mouths. Because several studies have shown that this "gape limitation" can be very important in influencing interactions between piscivores and their prey, there should be differential effects of piscivores on populations of prey that differ in body shape. This differential predation may in turn influence the degree of piscivore-mediated cascading trophic effects on zooplankton and phytoplankton. Laboratory experiments will examine prey election by piscivorous largemouth bass (Micropterus salmoides) for two species of planktivores representing extremes in general body type: fathead minnows (Pimephales promelas), soft-rayed and shallow-bodied and bluegills (Lepomis macrochirus), hard-spined and deep bodied. A long-term pond experiment using 20 experimental ponds will also examine largemouth bass-fathead minnow and largemouth bass-bluegill interactions and their cascading effects on zooplankton and phytoplankton. The outcome of these experiments will test ecological theory and has immediate applied value in lake management.