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REGIONAL TRANSPORT AND SECONDARY SPREAD OF INVASIVE SPECIES ACROSS PACIFIC ESTUARIES
Citation:
BLUM, M. J., M. BAGLEY, J. CABREZA, A. OTA, AND E. MCNAUGHTON. REGIONAL TRANSPORT AND SECONDARY SPREAD OF INVASIVE SPECIES ACROSS PACIFIC ESTUARIES. Presented at 2005 EPA Science Forum, Washington, DC, May 16 - 18, 2005.
Impact/Purpose:
The objective of this task is to develop molecular indicators to evaluate the integrity and sustainability of aquatic fish, invertebrate, and plant communities (GPRA goal 4.5.2). Specifically, this subtask aims to evaluate methods for the measurement of:
fish and invertebrate community composition, especially for morphologically indistinct (cryptic) species
population genetic structure of aquatic indicator species and its relationship to landscape determinants of population structure (to aid in defining natural assessment units and to allow correlation of population substructure with regional stressor coverages)
genetic diversity within populations of aquatic indicator species, as an indicator of vulnerability to further exposure and as an indicator of cumulative exposure
patterns of temporal change in genetic diversity of aquatic indicator species, as a monitoring tool for establishing long-term population trends.
Description:
San Francisco Bay is considered to be the most highly invaded estuary in North America, and is suspected of acting as a local source pool for secondary invasions of other Pacific estuaries. With support from the Regional Applied Research Effort programs in EPA Regions 9 and 10, we have initiated research to determine whether invasive species introduced to San Francisco Bay are spreading to other Paciifc estuaries via regional ship traffic. This work will identify and characterize invasion pathways across Pacific estuaries by determining whether populations of invasive species distributed across Pacific estuaries are derived from San Francisco Bay populations as opposed to overseas sources. We are addressing this concern by evaluating patterns of genetic diversity across populations of ten invasive species sampled from California to Alaska. To determine whether ballast transport by regional shipping traffic is an important vehicle acting to spread invasive species from San Francisco Bay to other major Pacific estuaries, we are developing genetic screening tools to determine whether the ten invasive species are being carried in ballast originating from San Francisco Bay. By characterizing invasion pathways and transport profiles from cross-species comparisons, this research will facilitate early detection and monitoring programs, and will improve ballast water best management practices designed to eliminate or restrict the spread of invasive species across Pacific estuaries. Results from the proposed research may also affect policy development for ballast regulation. Current ballast management programs focus on international shipping, but confirmation that San Francisco is a local source seeding other Pacific estuaries with exotic species would call for implementing stronger interstate and coastal ballast water regulations. Molecular screening tools designed to detect exotic species in ballast will also provide rapid and powerful methods for verifying whether vessels have complied with current management requirements.