Abundance of the Asian shore crab Hemigrapsus sanguineus in and adjacent to the Delaware Bay: evidence of invasive crash and return of native species

Schab, Corey
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University of Delaware
The Asian shore crab Hemigrapsus sanguineus has been introduced to multiple rocky habitats outside its native range and is considered an invasive species on the East Coast. The Delaware Bay region represents one of these locations and contains established populations of this intertidal, brachyuran species. Previous studies conducted in the University of Delaware Harbor, a location within this invaded region, indicated that H. sanguineus had displaced native mud crabs as the dominant species in this habitat. This trend had been observed at many locations in the North American range of the species. However, surveys conducted a decade later, during 2011 and 2012, have indicated a reverse in the previous trend and have shown significantly higher abundance and biomass of Panopeus herbstii, a native mud crab, compared to H. sanguineus. These results document the first evidence of a decline in the population of H. sanguineus along the East Coast of the USA.