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Aquatic Research Consortium Year 2
A Genomic and Proteomic Approach for Detection of Environmental Stress Responses in Small Fish Models
Issue
Currently, the effects of hypoxia on the plants and animals living in an ecosystem experiencing low oxygen levels coincide with a reduction of demersal fish and death of benthic fauna. Prolonged exposure to hypoxia results in behavioral or physiological changes such as increased ventilation frequency and cardiac output in both fish and crustaceans. While these responses are valuable indices of low oxygen conditions, they cannot serve as effective hypoxia biomarkers since they involve in situ measurements of the organisms and are not practical for monitoring. Indicators of hypoxia at the organism and cellular level are needed to assess the onset, duration and severity of chronic as well as intermittent hypoxia and its effect on biota. Genes that respond to hypoxia can potentially serve as indicators of hypoxic stress. Eutrophication is often accompanied or exacerbated by toxic chemical inputs of heavy metals and polycyclic aromatic hydrocarbons (PAHs from urban runoff) endocrine disrupting chemicals (from sewage treatment plants), pesticides and herbicides (from agricultural runoff). By providing resource managers with sensitive early-warning indicators of potential problems with the population, Aquatic Research Consortium’s (ARC) goal is development of stressor-specific diagnostic tools which indicate initial ecological change due to decreased water quality. Such indicators are of vital importance for effective management of ecological systems because they will allow proactive rather than reactive strategies for restoring ecosystem health. The indicators will be critical for rapidly evaluating the success of environmental remediation efforts.
Approach
The sheapshead minnow (Cyprinodon variegates), a small fish that ranges from Cape Cod to the Gulf of Mexico will be used mainly for genomics studies conducted at the Gulf Coast Research Laboratory. This facility has a long history of maintaining, spawning and testing this species. Platyfish or Swordtails (Xiphophorus Spp.) and will mainly be used by researchers at Texas State University as a model system to investigate, identify, and validate the biological effects of hypoxia/anoxia exposure. Once biomarkers are identified, they can then be validated for use on existing feral fish populations in conjunction with the Gulf Coast Research Laboratory.
By investigating the effects of environmental contaminants on aquatic organisms in laboratory and field-based exposures, researchers will attempt to link gene and protein expression profiles to biologically relevant endpoints such as reproduction and immune function. Eventually, the findings of these studies will help identify effects at higher levels of biological organization, such as communities and ecosystems. In addition, such research will identify populations differing in their sensitivities to contaminant-induced immunotoxicity. This allows investigation of the molecular mechanisms behind resistant and sensitive populations.
Accomplishments
Chronic stressors can cause cumulative effects that result in reduced fitness, culminating in population decreases. By the time such effects are observed, conditions may have deteriorated to levels that are difficult or expensive to remedy. The stressor-specific diagnostic tools developed in this research project will provide resource managers with sensitive early-warning indicators of potential population effects and incipient ecological change due to decreased water quality. Such indicators are of vital importance for effective management of ecological systems because they allow proactive rather than reactive strategies for restoring ecosystem health. The indicators will be critical for rapidly evaluating the success of environmental remediation efforts.
Management and Policy Implications
The main objective of ARC is to develop the next generation of molecular indicators, based on a genomics and proteomics approach, to detect environmental stress responses in fish, determine population differences in stress responses and link these indicators in individuals to responses at the population level. Chronic stressors can cause cumulative effects that result in reduced fitness, and population level. By the time such effects are observed, conditions may have deteriorated to levels that are difficult or expensive to remedy.