Ecological Consequences of Herbivore Adaptation to Toxic Cyanobacteria: Implications for the Control of Freshwater Harmful Algal Blooms

EPA Grant Number: FP917317
Title: Ecological Consequences of Herbivore Adaptation to Toxic Cyanobacteria: Implications for the Control of Freshwater Harmful Algal Blooms
Investigators: Chislock, Michael F
Institution: Auburn University Main Campus
EPA Project Officer: Packard, Benjamin H
Project Period: September 1, 2011 through August 31, 2014
Project Amount: $126,000
RFA: STAR Graduate Fellowships (2011) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Water Quality: Hydrogeology and Surface Water


Toxin-producing cyanobacteria have frequently been hypothesized to limit the ability of herbivorous zooplankton (such as Daphnia) to control phytoplankton biomass by inhibiting Daphnia feeding, population growth, and in extreme cases, causing Daphnia mortality. However, recent research has shown that populations of the generalist herbivore, Daphnia, can evolve to tolerate cyanobacteria and their associated toxins following prolonged exposure to cyanobacterial blooms. The objectives of the proposed research are to understand the ecological consequences of Daphnia adaptation to toxic cyanobacteria and to determine the implications of herbivore evolution for the control of harmful algal blooms in nature.


This research will use Daphnia as a model organism for studying the role of herbivore adaptation in food webs. Daphnia and cyanobacteria provide an ideal system to examine the consequences of herbivore adaptation as Daphnia are keystone herbivores in the pelagic zone of lakes and cyanobacteria can have negative effects on community structure and function. As Daphnia can evolve to tolerate toxic cyanobacteria, the response of eutrophic ecosystems to abatement efforts may depend on the role of Daphnia adaptation to cyanobacteria. This study will test this hypothesis using a combination of laboratory feeding assays, limnocorral experiments and whole pond experiments.

Expected Results:

The presence of Daphnia seems to be critically important to the success of biomanipulation efforts and understanding the causes and consequences of intraspecific variation within Daphnia, for traits conferring tolerance to toxic cyanobacteria may aid in the future management of eutrophic lakes. It is anticipated that the results of this research will add to a growing body of literature emphasizing the importance of variation within species for community dynamics and ecosystem function. Furthermore, management of Daphnia populations tolerant of toxic cyanobacteria may provide a sustainable alternative for the control of freshwater harmful algal blooms. The results of this work will be directly applicable to the control of toxic cyanobacterial blooms in aquaculture ponds and in municipal drinking water systems.

Potential to Further Environmental / Human Health Protection

This research will have significant impacts on science and society by: (1) advancing knowledge of the role of keystone herbivore adaptations in controlling harmful algal blooms, (2) improving management of harmful algal blooms through biomanipulation, (3) teaching outreach courses to diverse audiences, and (4) mentoring high school and undergraduate students. Cyanobacterial toxins have been implicated in the poisoning of drinking water supplies, food webs, pets and humans. Despite dramatic improvements in water quality since the enactments of the Clean Water and Safe Drinking Water Acts in the 1970s, eutrophication and cyanobacterial blooms are still prevalent in surface waters across the United States. This research aimed at the improved management of toxic cyanobacterial blooms has potential benefits to society with respect to water quality, livestock production, aquaculture and human health.

Supplemental Keywords:

intraspecific variation, eutrophication, biomanipulation, harmful algal blooms, toxins, toxic cyanobacteria, herbivore, adaptation, Daphnia, aquaculture

Progress and Final Reports:

  • 2012
  • 2013
  • Final