Distribution of Gammaridean Amphipoda (Crustacea) 

 in the Middle Atlantic Bight Region 



JOHN J. DICKINSON,' ROLAND L. WIGLEY/ RICHARD D. BRODEUR,^ 

 and SUSAN BROWN-LEGER'* 



ABSTRACT 



The distribution and abundance of 101 species of marine benthic gammaridan amphipods are de- 

 scribed for the Middle Atlantic Bight region. This report is based on 669 quantitative grab samples 

 from 563 stations on the continental shelf and upper continental slope between Cape Cod, Mass., and 

 Cape Hatteras, N.C. The amphipod fauna from the open shelf is most completely represented, but 

 deep-sea and estuarine species are also included. The abundance of each species is reported in terms of 

 its numerical density. Geographic and bathymetric distributions, and sediment relationships are also 

 reported for each species. 



INTRODUCTION 



This report is based on collections of gammaridean 

 amphipods from the Middle Atlemtic Bight made by the 

 Benthic Invertebrate Project at the Northeast Fisheries 

 Center Laboratory of the National Marine Fisheries Ser- 

 vice at Woods Hole, Mass. These collections were ob- 

 tained as part of a reconnaissance of the entire Atlantic 

 coastline designed to obtain an overview of the general 

 composition and distribution of the macrobenthos 

 (Wigley and Theroux In press). 



Amphipods were not specifically sought in making 

 these collections, but they were a major component in 

 the macroinfaunal communities sampled. Gam- 

 maridean amphipods composed 40% of the number of 

 specimens and 2% of the biomass of these Middle Atltin- 

 tic Bight collections (Wigley and Theroux In press). 



The importance of amphipods in the Northwest 

 Atlantic has also been indicated by the results of food 

 studies, which found that gammarideans were fi-equent 

 prey items in the stomachs of over 40 8i}ecie8 of fishes 

 and were often the principal prey for the juvenile stages 

 of several commercially important fishes (Bowman and 

 Langton 1978). 



The region between Cape Cod, Mass., and Cape Hat- 

 teras, N.C, is inhabited by about 150 species of gam- 

 maridean amphipods on the continental shelf (Bous- 

 field 1973) with the likelihood of another 100 species 



'Northeast Fisheries Center Woods Hole Laboratory, National Marine 

 Fisheries Service, NOAA, Woods Hole, Mass.; present address: 

 National Museum of Canada Ottawa, Canada KIA 0M8. 



"Northeast Fisheries Center Woods Hole Laboratory, National Marine 

 Fisheries Service. NOAA. Woods Hole, MA 02543. 



Northeast Fisheries Center Woods Hole Laboratory, National Marine 

 Fisheries Service, NOAA, Woods Hole, Mass.; present address: Graduate 

 School of Oceanography, Oregon State University, Corvallis, OR 97331. 



'Northeast Fisheries Center Woods Hole Laboratory, National Marine 

 Fisheries Service, NOAA, Woods Hole. Mass.; present address: Woods 

 Hole Oceanographic Institution, Woods Hole, MA 02543. 



occurring at bathyal and abyssal depths (Hessler and 

 Sanders 1967). The continental shelf fauna is relatively 

 well known with only a small number of new species to 

 be described. The deepwater amphipod fauna of this 

 area is poorly known with less than half the species 

 presently described. Bousfield's (1973) excellent 

 systematic monograph on the shallow-water amphipod 

 fauna of New England includes most of the species en- 

 countered in the Middle Atlantic Bight, and it also pro- 

 vides a concise summary of the geographic range, bathy- 

 metric distribution, £tnd sediment preference of each 

 species. This reference served as the primary taxonomic 

 source in identifying our gammarideans. Other useful 

 taxonomic studies consulted were Sars (1895), Holmes 

 (1905), Chevreux and Fage (1925), Shoemaker (1930a, b, 

 1945a, b), Stephensen (1935), Gurjanova (1951), Bar- 

 nard (1960, 1969, 1971, 1972), Mills (1962, 1967b, 1971), 

 Bousfield (1965), Barnard and Drummond (1976), 

 Bynum and Fox (1977), and Laubitz (1977). 



This report presents distributional data for 101 

 species of benthic gammaridean amphip>ods repre- 

 senting 55 genera in 17 families. The majority of the 

 species (75%) are continental shelf forms, but both 

 deep-sea (15%) and estuarine (10%) forms are also rep- 

 resented. Amphif)od species characteristic of sand and 

 mud are well represented in our collections, but sp>ecies 

 associated with rock and gravel bottoms are incom- 

 pletely represented, reflecting the scarcity of hard sub- 

 stratum in the areas sampled. 



In addition to the records of occurrence for all species, 

 this report presents detailed breakdowns by latitude, 

 depth, and sediment type of the numerical density es- 

 timates for the more abundant gammaridean species. 

 The distributional data resulted in many extensions of 

 both geographic and bathymetric ranges. In general, 

 this report represents an addition to our knowledge of 

 the distribution and abundtmce of the gammaridean 

 amphipods of the Middle Atlantic Bight, particularly in 

 the offshore areas of the coninental shelf. 



