Nearshore zonation of benthic fauna, especially Nematoda, in Loch Etive

Abstract

The vertical distribution of the benthic fauna, including Nematoda, of soft sediments in shallow water was studied along nearshore transects at two sites in Loch Etive and compared with transects worked there previously. The mathematical techniques of hierarchical classification and reciprocal averaging ordination were applied to the species abundances along the transects in an attempt to summarize the data and describe the faunal zonation in a clear and objective way. The inverse reciprocal averaging ordination of pooled transect data described the zonation for all species at each site as a faunal gradient with a single large step at a depth where hydrographic conditions were most variable. This was the most satisfactory description of zonation since it indicated the pattern of sharp faunal change at these critical depths better than previously and allowed direct comparison between transects.The vertical distribution of the Nematoda alone could be simplified to a pattern which paralleled that of the other fauna. A single step or break demarcated a shallow brackish assemblage from a typically marine assemblage found in deeper water. Comparison with brackish fauna of the Baltic and from British estuaries illustrate the coherent nature of the brackish component. Zonation of many nematode species paralleled closely previously published descriptions of zonation in the Exe estuary, indicating the dominant effect of salinity governing distribution along the Etive transects.Classification techniques based on faunal indices of affinity between stations along the transects were less satisfactory. Different indices of faunal similarity yielded different patterns of hierarchy, although an index based on presence/absence data yielded results similar to reciprocal averaging.A group of species intermediate between the brackish and marine elements was isolated from the non-nematode component, but this was not reflected in the nematodes.

An experimental protocol to select nematode species from an entire community using progressive sedimentary enrichment

“…Wieser (1953Wieser ( , 1959b, Tietjen (1969), Warwick and Gage (1975), Coull and Bell (1979), Boucher (1972), Vitiello (1974), andJuario (1975). In general, these authors found that muddy sediment is dominated by 1B and sand by 2A.…”

Structure and taxonomic composition of subtidal nematode and macrofauna assemblages at four stations around the UK coast

“…Reports contributing to the knowledge of the distribution of nematodes from stable subtidal environments in the British Isles are rare. It is di⁄cult to make valid comparisons with other studies as most of the earlier work deals with meiofauna assemblages along natural (Warwick & Buchanan, 1970;Warwick, 1971;Warwick & Gage, 1975) or pollution gradients (Ward, 1973;Lambshead, 1986;Somer-¢eld et al, 1994aSomer-¢eld et al, ,b, 1995. At the locations sampled during this study, approximately one-third of all nematodes were Sabatieria punctata, a species commonly dominating in muddy subtidal sediments (Steyaert et al, 1999).…”

Checklist of the subfamily Adoncholaiminae Gerlach and Riemann, 1974 (Nematoda: Oncholaimida: Oncholaimidae) of the world: genera, species, distribution, and reference list for taxonomists and ecologists

“… Adoncholaimus lepidus nec Adoncholaimus lepidus sensu Warwick and Gage 1975 : see Adoncholaimus panicus …”