El Niño Range Extensions of Pacific Sand Crab (Emerita analoga) in the Northeastern Pacific

Abstract

Many marine species are shifting poleward with global climate change, and many move on a shorter-term basis with periodic climate variations such as the El Nino Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO). The Pacific sand crab Emerita analoga (Crustacea: Decapoda: Anomura: Hippidae) is a dominant member of the wave-exposed sandy beach macrofauna of California and Oregon. Its occasional records from Washington to Alaska have been taken to correspond to ENSO events. However, there are surprisingly few scientific or citizen-science records of its presence in this region. We report the first published record in over 30 years of E. analoga in British Columbia, and summarize historical published and unpublished records. Because this species is conspicuous and readily identifiable, we suggest the general absence of its published, institutional, and citizen-science records coincident with most historical ENSO events may be due to a lack of reporting. In California, E. analoga accumulates harmful algal bloom toxins, is consumed by crabs, fish, birds, and marine and terrestrial mammals, and serves as the intermediate host for a variety of parasites, including the peritonitis-inducing acanthocephalan implicated in sea otter mortalities. As coastal waters warm, we predict that E. analoga will colonize sandy beaches north of its current range, where it may serve as an abundant prey item and as a vector for the trophic transfer of toxins and parasites. Detecting changes in its abundance will require the continued observation and reporting of its records, which we encourage in academic, government, and citizen-science venues.