Spatial patterns of richness and abundance of benthic decapod crustaceans and fishes in the North-west Atlantic as measured by cobble-filled bio-collectors

ABSTRACT

Examination of spatial patterns of organisms in the rocky subtidal zone is logistically challenging, particularly over large geographic distances. In the present study, we describe patterns of richness and abundance of decapod crustaceans and small demersal fishes colonizing cobble-filled bio-collectors in 2008 and 2009 at nearshore sites across an important oceanographic and biogeographic gradient in the North-west Atlantic from Rhode Island, USA to Newfoundland, Canada. At least 17 decapod and 24 fish genera were caught, including cryptic fish taxa not readily sampled with other gear. Species richness and abundance of decapods and fishes in collectors at shallow sites (5–10 m) was similar among nearby sites and was greatest in the southernmost region, but did not follow a simple latitudinal cline. The lack of clear latitudinal patterns is likely to be a result of the complex geography of summer temperatures along this coast, with the lowest temperatures at the mouth of the Bay of Fundy, the centre of the study domain. In 2008, the abundance of crabs was positively related to temperature while that of shrimp was negatively related. There was also a significant interaction between depth and study area, with greater similarity among areas at greater depths (up to 76 m), and greater similarity among depths in areas with little temperature stratification. Our results indicate that bio-collectors are a powerful tool for sampling decapod crustaceans and small demersal fishes in nearshore rocky habitats. Given the anthropogenic impacts in coastal habitats, this information is likely to prove useful for detecting changes in rocky subtidal habitats.

RESPONSIBLE EDITOR:

• Alf Josefson

KEYWORDS:

• Biodiversity
• decapod crustaceans
• fishes
• rocky subtidal
• spatial patterns
• temperature

Acknowledgements

Fish and decapod data from additional sites were provided by Victoria Burdett-Coutts (NL), Robert Glenn (MA), Mark Gibson (RI, 2009) and Bruce Hatcher (Sydney, NS), and sea surface temperature estimates were provided by Brady Quinn. Special thanks go to the fishing industry collaborators and the Fishermen and Scientists Research Society who assisted with deployment and retrieval of collectors, and to the many people who assisted with processing the collectors in the field and in the laboratory.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Financial support was provided by Natural Sciences and Engineering Research Council of Canada grants to Rémy Rochette, Heather Hunt and Paul Snelgrove, a US National Oceanic and Atmospheric Administration Northeast Consortium grant and a US Department of Agriculture National Institute of Food and Agriculture Hatch grant to Richard Wahle, a Commercial Fisheries Research Foundation grant to Robert Glenn, and Fisheries and Oceans Canada.