A cocktail of contaminants: how mixtures of pesticides at low concentrations affect aquatic communities

  title={A cocktail of contaminants: how mixtures of pesticides at low concentrations affect aquatic communities},
  author={Rick A. Relyea},
  • R. Relyea
  • Published 1 March 2009
  • Environmental Science
  • Oecologia
The ubiquity of anthropogenic chemicals in nature poses a challenge to understanding how ecological communities are impacted by them. While we are rapidly gaining an understanding of how individual contaminants affect communities, communities are exposed to suites of contaminants yet investigations of the effects of diverse contaminant mixtures in aquatic communities are rare. I examined how a single application of five insecticides (malathion, carbaryl, chlorpyrifos, diazinon, and endosulfan… 

A tale of two pesticides: how common insecticides affect aquatic communities

These results suggest that these common pesticides, which share the same mode of action, have similar effects on zooplankton and algae, but differences in the strength and timing of their effects on tadpoles reduce the generality of responses at higher trophic levels.

Effect of pesticides on microbial communities in container aquatic habitats

It is suggested that exposure of aquatic ecosystems to individual pesticides or their mixtures can disrupt aquatic microbial communities and there is need to decipher how these changes affect resident macroinvertebrate communities.

Effects of endosulfan in freshwater pond communities

It is demonstrated that endosulfan can initiate a wide range of direct and indirect effects on nontarget organisms and interacts additively with lethal predators.

The effect of a common pyrethroid insecticide on wetland communities

Within the past decade, the use of pyrethroid insecticides has drastically increased. While they are known to be directly toxic to aquatic organisms, based primarily on lab experiments, they are not

Chemical cocktails in aquatic systems: pesticide effects on the response and recovery of >20 animal taxa.

A synthesis of the effects of pesticides on microbial persistence in aquatic ecosystems

Examination of community-level, indirect effects revealed that all pesticide categories had a tendency to reduce higher trophic levels, thereby diminishing top-down pressures and favoring lower trophIC levels.

Effects of the Herbicide Metolachlor and Fish Presence on Pond Mesocosm Communities

Abstract. The effects of many pesticides on aquatic ecosystems remain poorly understood, especially in naturalistic communities in which organisms are connected by a complex array of direct and

Pesticides alter ecosystem respiration via phytoplankton abundance and community structure: Effects on the carbon cycle?

Given that ponds release atmospheric carbon and that worldwide pesticide pollution continues to increase exponentially, scientists and policy makers should pay more attention to the ways pesticides alter the carbon cycle in ponds via changes in communities, as demonstrated by the results.

The combined influence of two agricultural contaminants on natural communities of phytoplankton and zooplankton

The lack of significant toxicity of Roundup WeatherMax alone, as well as the observation of delayed interactive or indirect effects of the mixture of herbicide and nutrients attest to the value of manipulative field experiments as part of a comprehensive, tiered approach to risk assessments in ecotoxicology.




This study represents one of the most extensive experimental inves- tigations of pesticide effects on aquatic communities and offers a comprehensive perspective on the impacts of pesticides when nontarget organisms are examined under ecologically relevant conditions.


Environmental realistic concentrations of atrazine and endosulfan influence the structure of a pond community when the presence of common community members was manipulated but the initial composition of the community influenced these pesticide effects.

An unforeseen chain of events: lethal effects of pesticides on frogs at sublethal concentrations.

  • R. RelyeaNicole Diecks
  • Environmental Science
    Ecological applications : a publication of the Ecological Society of America
  • 2008
Examining how low concentrations of a globally common insecticide applied at various amounts, times, and frequencies affected aquatic communities containing zooplankton, phytoplankon, periphyton, and larval amphibians for 79 days found the mechanism underlying the trophic cascade is common to a wide range of insecticides, offering the possibility of general predictions for the way in which many insecticides impact aquatic communities and the populations of larval frogs.

Pesticide Mixtures, Endocrine Disruption, and Amphibian Declines: Are We Underestimating the Impact?

Estimating ecological risk and the impact of pesticides on amphibians using studies that examine only single pesticides at high concentrations may lead to gross underestimations of the role of pesticides in amphibian declines.

Growth and survival of five amphibian species exposed to combinations of pesticides

  • R. Relyea
  • Environmental Science
    Environmental toxicology and chemistry
  • 2004
The impact of combining these four pesticides is similar to that predicted by the total concentration of pesticides in the system, which suggests that the global decline of amphibians has sparked interest in the role that pesticides may play.

Aquatic risk assessment of a realistic exposure to pesticides used in bulb crops: A microcosm study

In this experiment, the first-tier risk assessment procedure for individual compounds was adequate for protecting sensitive populations exposed to realistic combinations of pesticides and spray drift reduction measures seem to be efficient in protecting aquatic ecosystems in agricultural areas.

Assessing the ecology in ecotoxicology: a review and synthesis in freshwater systems.

This article assesses how pesticides affect freshwater systems by applying the conceptual framework of density- and trait-mediated indirect effects from the field of basic ecology and demonstrates the utility of this framework for understanding the conditions under which pesticides affect species interactions, communities and ecosystems.

Effects of a Mixture of Two Insecticides in Freshwater Microcosms: II. Responses of Plankton and Ecological Risk Assessment

It was found that the safety factors set by the Uniform Principles for individual compounds also ensure protection against chronic exposure to a mixture of insecticides at community level, though not always at species level.

Indirect effects of contaminants in aquatic ecosystems.

Effects of nutrient loading and planktivory on the accumulation of organochlorine pesticides in aquatic food chains

The results demonstrate that fish predation and nutrient loading can modify the size-related processes of HOC partitioning and affect its accumulation in the aquatic food chain.