Nonindigenous near-coastal and estuarine species in the North Pacific: Similarities and disparities in species invasion patterns

Background/Question/Methods

Nonindigenous species (NIS) are a pervasive problem throughout the world.  To help address this threat, the EPA and USGS developed a hierarchical database known as the Pacific Coast Ecological Information System (PCEIS) that synthesizes existing biogeographic, life history, and invasion histories for NIS species in near-coastal and estuarine habitats.  This database allows us to investigate invasion patterns from subregional (i.e. ecoregion) to global scales using a modified Marine Ecoregions of the World (MEOW) schema as the basis for biogeographic mapping; our modification is an added “region” level between the province and realm levels dividing the Pacific Ocean into its eastern and western coastal regions. We are using PCEIS to assess the extent and patterns of invasion in the North Pacific, specifically the Northeastern Pacific (NEP) and Northwestern Pacific (NWP) regions and the Hawaii ecoregion.

Results/Conclusions

There were 747 NIS identified in the North Pacific, of which 368 occurred in the NEP, 347 in Hawaii, and 208 in the NWP. Recognizing the significance of the language barriers among these regions, we attempt to explain the reason for such a large discrepancy in numbers of NIS. For example, the greatest similarity between the NEP and the NWP was in the number of biofouling species, which are well studied in the NWP. Nonetheless, the NWP has a more variable climate than the NEP as measured by the monthly and seasonal near-coastal sea surface temperatures. Hawaii was the most heavily invaded ecoregion in the North Pacific, having more NIS than the Northern California ecoregion (243 NIS) encompassing San Francisco Bay, a system widely regarded as being the most heavily invaded estuary in the continental United States.  Most of the first records in Hawaii originated from either Pearl Harbor or Kaneohe Bay, which combined have a total area of 66 km² compared to San Francisco Bay at 4,100 km².  Our analysis will highlight differences among NIS in the NEP, NWP, and Hawaii; examining sources and vectors to explain the current patterns of NIS occurrences in the North Pacific.