Community structure of bathyal decapod crustaceans off south-west Balearic Islands (western Mediterranean): seasonality and regional patterns in zonation

Abstract

The community structure of decapod crustacean assemblages was established and analysed from two experimental trawl samplings. The data were taken in the south-west Balearic Islands (Algerian Basin, western Mediterranean Sea) at depths ranging from ∼200 to 1800 m. The results of multivariate analysis indicate that the community structure remained constant between samplings. The analysis also revealed that there exist differences between bathyal decapod communities at a regional level (<1000 km) when compared with well-studied nearby areas. The differences relate mainly to the relative contribution of different species and feeding guilds, not to the taxonomic composition of the assemblages studied. It is proposed that these differences result from contrasting surface production regimes (coastal vs open sea) and food web organization (relative dependence on mesopelagic or infaunal prey).

Demersal resource assemblages in the trawl fishing grounds off the Balearic Islands (western Mediterranean)

“…However, the comparison of our results with these studies, which only made a qualitative analysis of fish and cephalopod species respectively, revealed that the distribution of the demersal resources is more complex than that previously found (only four assemblages). Moreover, the comparison of our results with those obtained from the quantitative analysis of different taxonomic groups undertaken in other areas of the Mediterranean also shows that the bathymetric distribution of demersal resources, considered as a whole, is also more complex than those associations found within the separated groups of cephalopods, crustaceans and fishes (González and Sánchez, 2002;Maynou and Cartes, 2000;Demestre et al, 2000;respectively). On the other hand, our results are similar to those obtained from the analysis of the whole demersal macrofauna developed in the central (Biagi et al, 2002;Colloca et al, 2003) and eastern (Kallianiotis et al, 2000) Mediterranean, which identified assemblages on the coastal shelf, middle shelf, shelf-edge, shallow upper-slope and deep upper-slope.…”

“…-Bathymetric distribution of invertebrate species (decapod crustaceans, cephalopod molluscs and the holothurian echinoderm) in terms of centre of gravity and habitat from the BALAR0401 (black circles) and BALAR0901 (white squares) surveys. Black arrows indicate a displacement in real terms of the centre of gravity beyond the depth range sampled, according to other studies conducted in the same and adjacent areas (Maynou and Cartes, 2000;Quetglas et al, 2000). Numbers 1-8 correspond to the eight depth intervals into which the bathymetric range sampled was divided (see Material and Methods).…”

“…The higher abundance of Plesionika species in the western sector could be due to the absence of submarine canyons in this area (the only submarine canyon is located on the southern coast of Menorca; Canals and Ballesteros, 1997), which can contribute to a distinct trophic web structure and energy flow in deep-sea ecosystems. According to Maynou and Cartes (2000), deposit and infaunal feeder species are more characteristic of communities in which the inputs of organic carbon via submarine canyons are an additional source of food resources, while the pandalids dominate on demersal communities whose trophic resources are of planktonic origin. In addition, the seasonal differences in species of the genus Plesionika can be related to their reproductive pattern.…”

Body fish size tendencies within and among species in the deep-sea of the western Mediterranean

“…Thus, the minor availability of trophic resources above and below this depth interval may ultimately determine the lower biomass characterising the upper and lower slope fish assemblages (see also Stefanescu et al, 1993). On the other hand, the biomass of another major group of predators, namely the decapod crustaceans, which also prey on the suprabenthos (Cartes, 1994;1998b) peaks between 400-700 m (Maynou and Cartes, 2000), and Cartes et al (2001) have suggested that this may originate a phenomenon of competitive exclusion in favour of the latter group of megafaunal predators at this depth interval due to the exploitation of similar resources.…”

Size Influence in Zonation Patterns in Fishes and Crustaceans from Deep-water Communities of the Western Mediterranean

“…Because of their dominance at mid-latitudes most studies have been on fish (Haedrich and Krefft, 1978;Gordon and Duncan, 1985;Haedrich and Merrett, 1990;Koslow, 1993;Fujita et al, 1995;Stefanescu et al, 1992;Moranta et al, 1998). Zonation has also been documented in other megabenthic taxa, such as crustaceans and other benthos (Rowe and Menzies, 1969;Abelló et al, 1988;Fredj and Laubier, 1985;Cartes, 1993;Cartes and Sardà, 1993;Maynou and Cartes, 2000). Comparative zonation studies between different groups are, however, scarce (Gage and Tyler, 1991), although the taxon factor, together with bottom topography, has been one of the most widely argued reasons to explain discrepancies in zonation (the intensity of faunal change with depth) at a regional scale (Gage and Tyler, 1991).…”