Fiddler on the roof: a northern range extension for the marsh fiddler crab Uca pugnax

Abstract

A northern range extension is presented here for the marsh fiddler crab Uca pugnax (Smith, 1870). In summer 2014, adult crabs were found as far north as Hampton, New Hampshire (42\textdegree55 27"N, 70\textdegree49 13"W), which is 80 km north of its previously established northern limit determined in 2003. Thus, the mean annual northern movement of U. pugnax is currently 7.2 km year-1. I hypothesize that crabs recruited to the most northern sites during 2012 or 2013 when ocean temperatures were up to 1.3\textdegreeC higher than the average of the previous decade. In a scenario of continued warming oceans associated with climate change, the range of U. pugnax is thus predicted to continue to extend northward. Given that fiddler crabs are ecosystem engineers affecting coastal wetland productivity, biogeochemistry and sediment structure, the introduction of this species into northern salt marshes may have consequences for marsh structure and function.