Cost-efficient methods for marine pollution monitoring at Casey Station, East Antarctica: the choice of sieve mesh-size and taxonomic resolution

Contaminants from sewage discharge and abandoned waste tips enter the marine environment adjacent to Australia’s Casey Station, East Antarctica. To establish cost-efficient methods for benthic pollution monitoring the effects of sieve mesh-size (0.5 and 1.0 mm) and taxonomic aggregation (family, order and class) on the description of infaunal assemblages were determined. The abundance and taxonomy of fauna retained on a 0.5 mm sieve after passing through a 1.0 mm sieve were examined in this study. The 1.0 mm sieve fraction [Human impacts and assemblages in marine soft-sediments at Casey Station, Antarctica, Ph.D. thesis, University of New England, 2001] contained 70% of individuals and 94% of taxa when compared to combined abundances on the 1.0 and 0.5 mm sieves. Furthermore, the addition of 0.5 mm data did not increase sampling precision or the statistical power to detect differences between locations. Differences between locations were detected when species were aggregated to the family level however, further aggregation to order and class levels altered the perceived pattern of differences. Marine pollution monitoring of the soft-bottom benthos at Casey Station is most cost-effective when using a 1.0 mm sieve and identifying fauna to the family level. This is the first reported comparison of sampling techniques using Antarctic benthos.