State Water Resources Research Institute Program

Project ID: 2007ME114B
Title: A Novel Approach to Assessing Multiple Stressor Effects in Maine Fishes
Project Type: Research
Start Date: 3/01/2007
End Date: 2/29/2008
Congressional District: second
Focus Categories: Water Quality, Toxic Substances, Agriculture
Keywords: agriculture, fisheries, herbicides, insecticides, land use, pest management, pesticides, pollutants, rivers, toxic substances, trace elements, water quality
Principal Investigators: Van Beneden, Rebecca; Drummond, Frank; Elskus, Adria; Perkins, Brian
Federal Funds: $ 7,197
Non-Federal Matching Funds: $ 60,159
Abstract: There is need for a rapid, biological screen to evaluate multiple stressor conditions in Maine's waters. Maine rivers and lakes feature a broad range of stressors, including acidity, aluminum (Al), endocrine-disrupting chemicals, organochlorines and pesticides. Many of these are present simultaneously. Exposure to a mixture of contaminants could have effects on fish that would not be predicted from exposure to individual stressors alone. For example, co-exposure of amphibians to the pesticide carbaryl in the presence of predator scent increased carbaryl toxicity 2-4 fold relative to carbaryl exposure alone [1]. Of particular concern for fish in Maine's Downeast rivers (Washington County) is the combination of blueberry pesticides, acidic water and elevated levels of Al, each of which has been implicated in hindering the recovery of endangered Maine Atlantic salmon (Salmo salar) [2]. Whether the pesticide mixtures alone, or in combination with high acidity and elevated Al levels, adversely affect fish health, is unknown. An additional concern is the need to provide input on the effects of proposed changes, including alterations in pesticide usage and plans to neutralize river acidity. For example, the Maine blueberry industry currently proposes to replace two of the pesticides found consistently in Maine rivers, phosmet and hexazinone, with candidate alternatives, spinosad and mesotrione, for which fish early life stage effects have not been evaluated. Plans by NOAA-Fisheries to neutralize the acidity of Downeast rivers as a mitigation tool have been put on hold until more information is available on the potential beneficial/detrimental effects of this action [3]. The slow developmental rate and seasonal limitations of egg production preclude the use of Atlantic salmon early life stages in toxicant screens. Therefore, we propose to conduct an initial evaluation of zebrafish (Danio rerio) early life stages as a high through-put screen to assess pesticide/acid/aluminum conditions that may be harmful to fish. Due to their rapid developmental rate (fertilization to feeding in 5 days), transparent embryos, low cost, and the high degree of conservation of vertebrate developmental genes, zebrafish are widely used for studying toxicity mechanisms in vertebrates, particularly in early life stages [4, 5]. Because fish species can vary in their sensitivity to toxicants, we will expose zebrafish and Atlantic salmon early life stages to the same treatments to assess the utility of zebrafish as a model for Maine's endangered Atlantic salmon. Our overall objective is to evaluate the potential for a fast, inexpensive bioassay procedure for assessing the impact of multiple stressors on fish. Since functional impairment in early life stages is a more sensitive measure of the response to toxicants than mortality or morphological defects [6], we will evaluate performance fitness. We will screen stressor combinations in doses reflective of those in the rivers and 10-fold higher and evaluate fitness (immune function, prey capture) in zebrafish and salmon larvae. The results of this study will provide data on the potential effects of candidate pesticides on fish sensitive early-life stages before these pesticides come into use, determine whether neutralization of pesticide-contaminated river water is protective, and provide preliminary data for determining whether zebrafish are viable toxicant models for salmonids. If successful, this model system will be expanded to include additional classes of stressors identified in Maine rivers and provide a means by which to rapidly and efficiently evaluate the toxic potential of multiple stressors in aquatic ecosystems.

Progress/Completion Report, PDF

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