Differences in diversity, structure, and variability between intertidal and subtidal meiofaunal assemblages

Abstract

Meiofaunal assemblages from intertidal and shallow subtidal seabeds were studied at two sites (one dominated by volcanic sandsand the other by organogenic sands) at Tenerife (Canary Islands, NE Atlantic Ocean) throughout an entire year (May 2000–April 2001).Specifically, we aimed (i) to test for differences in diversity, structure, and stability between intertidal and subtidal meiofaunal assemblages, and(ii) to determine if differences in the meiofaunal assemblage structure may be explained by environmental factors (granulometric composition,availability of organic matter, and carbonate content in sediments). A total of 103,763 meiofaunal individuals were collected, including203 species from 19 taxonomic groups (Acari, Amphipoda, Cnidaria, Copepoda, Echinodermata, Gastrotricha, Isopoda, Insecta, Kinorrhyncha,Misidacea, Nematoda, Nemertini, Oligochaeta, Ostracoda, Polychaeta, Priapulida, Sipuncula, Tanaidacea, and Turbellaria). Nematodes werethe most abundant taxonomic group. Species diversity was higher in the subtidal than in the intertidal zone at both sites, as a result of the largerdominance of a few species in the intertidal zone. The meiofaunal assemblage structure was different between tidal levels at both sites, theintertidal presenting greater temporal variability (multivariate dispersion) in the meiofaunal assemblage structure than the subtidal. Sedimentgrain size, here quantified by the different granulometric fractions, explained the variability in meiofaunal assemblage structure to a greaterextent than the percentage of carbonates, a variable linked to sediment origin. This study revealed differences in diversity, assemblage structure,and variability between intertidal and subtidal meiofauna.