Abstract
Meiofaunal assemblages from intertidal and shallow subtidal seabeds were studied at two sites (one dominated by volcanic sands and 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, including 203 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 were the most abundant taxonomic group. Species diversity was higher in the subtidal than in the intertidal zone at both sites, as a result of the larger dominance of a few species in the intertidal zone. The meiofaunal assemblage structure was different between tidal levels at both sites, the intertidal presenting greater temporal variability (multivariate dispersion) in the meiofaunal assemblage structure than the subtidal. Sediment grain size, here quantified by the different granulometric fractions, explained the variability in meiofaunal assemblage structure to a greater extent 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.
Highlights
Sandy marine substrates are characterized by the presence, at first glance, of few macroscopic animals, most organisms inhabiting the spaces between grains of sediment
Disturbances associated with natural events such as wave action and runoff can occur with maximum intensity in the intertidal zone relative to the adjacent subtidal zone, where the increase in depth helps to mitigate their intensity and variability (Short 1999)
Several authors have observed that the meiofauna presents a different pattern, with richness and abundance decreasing in the subtidal zone relative to the intertidal (McIntyre and Murison 1973, McLachlan 1977, Reise 1985, Brown and McLachlan 1990)
Summary
Sandy marine substrates are characterized by the presence, at first glance, of few macroscopic animals, most organisms inhabiting the spaces between grains of sediment. Los sustratos arenosos marinos se caracterizan por la presencia, a primera vista, de pocos seres vivos macroscópicos, la mayoría de los organismos habitando en los espacios que Ciencias Marinas, Vol 38, No 4, 2012. These infaunal assemblages are composed of two components, macrofaunal and meiofaunal, that are related through complex food webs. While there is sufficient evidence that the biodiversity of hard-bottom macrofaunal assemblages increases as depth increases (Andres and Witman 1995, Witman and Grange 1998), there are few studies on the zonation patterns of soft-bottom infaunal communities, including their macroand meiofaunal components, from the intertidal to the subtidal zone (McLachlan and Brown 2006). Hydrodynamic forcing strongly affects the granulometric composition due to suspension and transport of sediment, and this affects the composition of the meiofaunal community because the settlement of interstitial (or other) species is determined by the degree of sediment stability (Gray and Elliott 2009)
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