Appropriate levels of taxonomic discrimination in deep-sea studies: species vs family

Few studies have investigated use of higher-level taxonomy, e.g. family, to analyse macrobenthic infaunal communities in the deep sea. This study uses multivariate analyses of polychaete macrofauna and environmental variables from 15 stations (depth 150 to 1000 m) situated in the Faroe-Shetland Channel (NE Atlantic). The data were analysed at species and family levels in order to determine the degree of taxonomic sufficiency required to discriminate between stations. There was little difference in results between species and family when using non-metric multidimensional scaling, however, cluster analysis and canonical correspondence analysis (CCA) showed marked differences between the 2 taxonomic levels. Similarity between stations was markedly lower at species than family level. The ability of CCA to separate the families into defined groups along the 2 ordination axes was more apparent than at species level. Families also tended to be more closely aggregated near the centre of the ordination plot. It is concluded that in the deep-sea, species-level identification of polychaetes is preferable to that of family-level identification.