Spatial patterns of benthic diversity: is there a latitudinal gradient along the Norwegian continental shelf?

Abstract

Summary 1.We examined data on soft-sediment macrobenthos (organisms retained on a 1-mm sieve) from a transect of c. 1960 km along the Norwegian continental shelf (56-71°N), covering a range of water depths (65-434 m) and varying sediment properties. 2. A total of 809 species was recorded from 101 sites. Of these, 36% were restricted to one or two sites, and 29% were represented by one or two individuals. No species spanned the entire transect. Polychaetes were the dominant taxonomic group, followed by crustaceans, molluscs and echinoderms. 3. Alpha diversity (sample species richness) was highly variable (35-148 species) but showed no evidence of a relationship to latitude or other environmental variables. 4. Beta diversity was measured as Whittaker's β W , the number of shared species, complementarity (biotic distinctness) and Bray-Curtis similarity, and there was no evidence of a latitudinal trend on the shelf. Beta diversity increased with the level of environmental variability, and was highest in the southern-central area, followed by the most northern area. Change in environmental variables had a stronger effect on beta diversity than spatial distance between sites. 5. Gamma diversity was computed by pooling samples over large areas. There was no convincing evidence of a latitudinal cline in gamma diversity, but gamma diversity increased with the level of environmental heterogeneity. Mean alpha diversity and gamma diversity were not significantly correlated. Whereas mean complementarity and mean Bray-Curtis similarity were related to gamma diversity, β W was not.

Species diversity, functional complexity and rarity in Arctic fjordic versus open shelf benthic systems

“…They noted that soft-bottom habitats are populated by small-sized species that do not occupy the whole habitat space available, and are thus open to constant immigrations (resulting in rare species occurrences). For example, proportions of uniques and duplicates recorded in present study (32 to 37%) are slightly lower, but roughly comparable to those documented for soft-bottom macrofauna in coastal waters off Norway (32 to 49%; Ellingsen & Gray 2002), Hong Kong (45%; Shin & Ellingsen 2004) and New Zealand (54%; Ellingsen et al 2007). The direct functional role of rare species in ecosystems remains largely unexplored, but their importance may stem from the complementarity of species functions and the 'insurance' value of biodiversity that is stored in large numbers of rare species (Loreau et al 2001).…”

Regional patterns of continental shelf polychaete diversity: examples for the North Sea, English Channel, Irish Sea and Outer Bristol Channel areas

“…The general circulation in the North Sea varies little with seasons and is in general cyclonic; Atlantic waters entering the North Sea from the north do not reach the continental coastline but turn gradually eastward towards the Jutland coast and the Skagerrak . The lack of a decline in diversity of polychaetes and other macrobenthic groups with latitude has also been documented by several authors (Kendall & Aschan 1993;Dauvin et al 1994;Kendall 1996;Ellingsen & Gray 2002;Kindlmann et al 2007;Renaud et al 2009), and as stated by the latter it could also be a consequence of the limited latitudinal range that only spans about 12…”

Tropical Coastal Habitats as Surrogates of Fish Community Structure, Grazing, and Fisheries Value

“…Because reefs on the same island are likely to have more similar abiotic, biotic, and hydrodynamical conditions than reefs on different islands, we hypothesized that reef-scale variability will be less than that observed at island scales. The increasing dissimilarity of communities within habitats, or increasing beta diversity, with increasing distance has been documented for both marine and terrestrial ecosystems (e.g., Condit et al 2002, Ellingsen andGray 2002).…”