Diversity and ecology of the marine tardigrades along the Apulian Coast

A comprehensive study on the composition, structure and diversity of tardigrade communities along the Southern Apulian coast was carried out in March and September 2000. The Apulian coastline counts about 820km and includes a wide variety of natural environments such as Torre Guaceto, Laghi Alimini and Porto Cesareo and areas with high human impact such as Mattarelle (Enel power Station), Brindisi Harbour and Torre Mozza with its fish processing industry. The research was carried out only in the subtidal zone but in different kinds of sediments: coarse, medium, fine and very fine sand, sand in Posidonia meadows, coarse organogenous debris and mud. Seventeen stations were sampled at three different depths in two seasons: March and September, resulting in 86 samples of which 58 samples contained tardigrades. A total of 4288 specimens (2975 in March and 1313 in September) were identified to 52 species (51 in March and 36 in September). The tardigrade fauna along the Apulian coast are very rich, hosting more than 1/3 of all known arthrotardigrade species. The species found in Southern Italy belong to the arthrotardigrade families Neoarctidae (one species), Stygarctidae (four species), Halechiniscidae (42 species) and Batillipedidae (six species). Halechiniscidae is the most abundant family followed by Batillipedidae, Stygarctidae and Neoarctidae. The diversity, density and relative abundance were recorded, and the spatial variation of species diversity was statistically evaluated. Coarse sand which is found mainly at 10m depth seems to constitute the most favourable environment, which is evident from both species number and Shannon index H. Bray-Curtis cluster analysis combined with ordination by principal component analysis discriminate the species composition in three evident main clusters: coarse sand, fine sand and mud. Furthermore, the particular environmental factors in areas with sulphur springs, mussel farms as well as high seasonal tourism, seem to have a considerable impact on the species composition of these areas. © 2011 Blackwell Verlag GmbH.