Seascape biodiversity patterns along the Mediterranean and the Black Sea: lessons from the biogeography of benthic polychaetes

Abstract

The purpose of this paper is to investigate seascape biodiversity patterns along the Mediterranean and the Black Sea through the study of the benthic polychaete biogeography of the region. A set of non-parametric multivariate analyses and recently developed diversity indices were performed on the benthic polychaete inventories of the areas of the Mediterranean and the Black Sea. Both the numbers of species and the multivariate analyses demonstrate a west-east zoogeocline, shown by the decreasing number of species and by the multivariate similarity pattern of the areas. The performance of the 'second-stage' multi-dimensional scaling (MDS) shows, when species information is aggregated to genera, results belonging practically to the same similarity pattern, independent of the similarity coefficients utilized. The same similarity pattern is derived when species information is aggregated to the zoogeographical categories of amphi-Atlantic, Atlanto-Mediterranean, cosmopolitan and endemic species. BIO-ENV analysis reveals a large number of geographic, climatic and trophic variables to be highly correlated with the similarity pattern derived from the various taxonomic/zoogeographical categories. The synergy, however, of the environmental variables is best reflected in the case of the endemic Mediterranean species. The latter category is considered as the critical zoogeographic category with respect to providing information on the evolutionary history of the taxon in the region. The application of the average taxonomic distinctness and the variation of taxonomic distinctness indices resulted in a diversity ranking of the areas, which appears to be independent of the number of species hosted in each area. However, this is not the case for the phylogenetic diversity (PD) index. Additionally, the former 2 indices indicate that the benthic polychaete species-pool, hosted in the Mediterranean and the Black Sea areas, may well serve as a useful basis for future comparisons in environmental assessment studies. Finally, results from the application of the area-diversity formula show that the equilibrium model can be applicable for the endemic benthic polychaetes of the region: the number of endemic species can be considered as a function of the degree of isolation of the area from the source region against the degree of within-area isolated habitats.KEY WORDS: Biodiversity · Biogeography · Polychaeta · Mediterranean · Black SeaResale or republication not permitted without written consent of the publisher

Demosponge distribution in the eastern Mediterranean: a NW–SE gradient

“…Thus, the Aegean Sea ranks third in the Mediterranean in terms of demosponge diversity, following the western Mediterranean (80%) and the Adriatic (40%), although until recently its sponge fauna was considered underestimated (Pansini et al 2000). This scaling agrees with that for the Mediterranean octocorals (Vafidis et al 1994) and amphipods (Stefanidou and Voultsiadou 1995), but other groups such as decapods (Koukouras et al 1992), ascidians (Koukouras et al 1995), gastropods (Koutsoubas et al 1997) and polychaetes (Arvanitidis et al 2002) are represented by higher species numbers in the Aegean than in the Adriatic Sea.…”

“…Various invertebrate groups demonstrate this trend of decreasing endemism in the Mediterranean from west to east (Koukouras et al 2001). However, Arvanitidis et al (2002) did not find differences in the distribution of the zoogeographical categories of polychaetes among the Mediterranean areas. It is worth mentioning that none of the four Indo-Mediterranean species that entered the Levantine basin as lessepsian migrants (Tsurnamal 1969b) have been up-to-now found in the Aegean Sea.…”

“…The diversity of the Mediterranean fauna exhibits a west-to-east decline (e.g., Fredj et al 1992) with the western Mediterranean supporting about 87.1%, the Adriatic Sea 48.9% and the eastern Mediterranean 43.1% of the total Mediterranean species. This gradient has been more or less confirmed by several studies on certain benthic groups such as decapods (Koukouras et al 1992), prosobranch gastropods (Koutsoubas et al 1997), polychaetes (Arvanitidis et al 2002) and anthozoans (Vafidis 2002). The Aegean Sea, however, being the second major sea of the eastern Mediterranean after the Levantine, does not seem to follow this general trend since it supports higher species numbers than the latter and the Adriatic Sea.…”

Fauna asociada a la nacra <i>Pinna nobilis</i> (Mollusca: Bivalvia) en la costa norte y este de Túnez

“…the greater the species richness of a taxon for a particular habitat, the greater its sensitivity to changes in biological or environmental gradients. however, results have also demonstrated that each taxon (phylum level) might respond very differently to the others as consequence of its local representativeness, its relative composition of motile or sessile forms, its evolutionary history for that habitat and the potential breadth of its taxonomic/phylogenetic tree (Arvanitidis et al, 2002;Glasby, 2005). the notable occurrence of sessile filter-feeding species upon the shells of Pinna can support the possible existence of competition for nutrients, since the two parts belong to the same trophic guild.…”

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

“…Email: Francois.Schmitt@univ-lille1.fr (Knox 1977) and one of the richest invertebrate benthic taxa with regard to species number (Arvanitidis et al 2002). This group, which often dominates benthic macrofauna (Grémare et al 1998), is known to comprise mainly 60-70% of macrozoobenthic individuals on soft bottoms (Knox 1977;Dogan et al 2005), and can be used as 'markers' of different ecological conditions (Gambi & Giangrande 1986).…”