Objective

New methods for assessing the aquatic environmental condition of oceanic island streams will be developed from the analysis of genetic variation and otolith microchemistry of native amphidromous fishes across Hawaii.

Department of Defense (DoD) activities give rise to military and anthropogenic stressors that can threaten freshwater stream ecosystems on Pacific islands, and DoD personnel need improved stream assessment protocols for watershed management and restoration. Current protocols that rate condition based on measures of native fish species diversity are likely to underestimate impairment because fish assemblages of insular streams are naturally depauperate. Responses to environmental stressors also may be misunderstood since current protocols do not consider ocean-stream connectivity, even though most native stream fishes on Pacific islands are amphidromous (a life history involving both freshwater and marine stages). Genetic assessment protocols are promising alternatives to current approaches because analysis of genetic variation can reveal how environmental stressors affect individuals and populations within spatially explicit frameworks. However, use of genetic assessment protocols for Pacific islands requires identifying the factors responsible for variation in recruitment and dispersal of native amphidromous fishes.

The objective of this project is to develop and demonstrate genetic approaches for assessing the condition of Pacific island streams. Researchers first will examine whether local recruitment of native amphidromous fishes draws from mixed immigrant pools due to larval exchange across the Hawaiian archipelago. Results from this study will demonstrate the importance of ocean-stream connectivity. Researchers then will examine patterns of covariance between environmental stressors, population size, and immigration to assess how local recruitment varies according to in-stream conditions and watershed land use.