Cooperative Fish and Wildlife Research Units Program: West Virginia
Education, Research and Technical Assistance for Managing Our Natural Resources

A long-term monitoring multidisciplinary approach has been implemented to investigate smallmouth bass health issues in the Chesapeake Bay watershed, including sites in West Virginia from 2019-2021. Many factors naturally affect wild fish immunity, so the purpose of this study was to monitor and evaluate changes in immune function in context with other aspects of health and environmental factors, including complex interactions between water quality, contaminants, climatic factors, pathogens and parasites, and genetic changes. Analyses are ongoing for this project, including controlled exposures of laboratory fish leukocytes to environmentally relevant chemicals and development of a statistical model to parse out predictors of immune function in wild fish. Papers will be supplied as they are completed.
Some factors found so far to be associated with immune function in the wild smallmouth bass include surrounding land-use, chemical concentrations both in surface water and blood plasma of the host fish, and disease status of the host fish. Site, season, biometrics (sex, age, length, weight), and histopathological indicators (tissue parasites and macrophage aggregates) have also been found to be associated. Expression of immune- and contaminant-related gene transcripts will help explain immune function results and associations further. The ability to consistently monitor over multiple years/seasons and collect ancillary data has been paramount to understanding immune function results of wild smallmouth bass. Long-term monitoring has provided a baseline for wild fish immunity and ancillary data has provided context for their functional immune responses. Recognizing the complexity and interaction of multiple factors in understanding immune function, advanced statistics are needed and are our next steps in more comprehensively understanding relationships between immune function, various stressors, and other indicators of host health. Integration of lower-level responses like transcript abundance with higher levels responses like immune function will help to identify and ultimately understand adverse outcomes in wild smallmouth bass populations.