Description:

Objectives: We propose to focus on tropical and subtropical sites that are of particular importance to U.S. trade interests and that are strategically positioned for biogeographic considerations. Hypotheses include: (1) Number of invasive species increases, or conversely decreases, with decreasing latitude and increasing native diversity, i.e., tropical, high diversity ports are more or less at risk of biological invasion than temperate, lower diversity sites; (2) Number and proportion of invasive species is greater in island than continental ecosystems; (3) Rate of spread of invasive species among sites is related to life history characteristics; (4) Rate of new invasions is associated with vectors transporting species (e.g., shipping) and will decline with management efforts (e.g., ballast water exchange); (5) Invasive species do not respond to the same biogeographic boundaries in invaded regions as the native species present. Methodology: Over 2 years we will survey/sample 4 tropical ports (Puerto Rico, Hawai'i, Pacific side of Panama Canal, Belize) and 1 subtropical site (Indian River Lagoon, FL). We have already sampled the Caribbean entrance of Panama Canal. In combination, these sites will provide 5 tropical port systems of crucial interest to the US and international shipping, which can be compared to our larger array of higher latitude sites (12 West Coast, 8 East Coast, 4 Gulf Coast). We will use standardized settling plates and wooden blocks (220 per site) deployed at high salinities in a stratified random design. We will identify all fouling and boring species per plate/block after 3 mo soak time. Rationale: Despite numerous documented invasions of tropical marine systems, the perception that lower latitudes are less susceptible to invasions may result in part from reduced sampling effort and our poor taxonomic grasp of high native biodiversity in these systems. Tropical systems urgently need more study with standard surveys to test hypotheses and to predict risk of invasion. We will focus on fouling and wood-boring communities because: Fouling organisms comprise >180 species of ~300 non-native marine invertebrate species in North America and Hawai'i. These have large economic impacts on ships and in coastal waters. Many of the invasions derive from transfer in ballast water or on hull surfaces. SERC has successfully deployed fouling plate arrays to detect invasion patterns at larger scales.