Four infaunal replicate samples were collected at each site using 0.1 m2
Nioz corers (diameter of approximately 30 cm) were sieved on a 1mm mesh sieve,
the sieve remains were then sorted and preserved following the methodology
described by Boyd (2002). On return, to the laboratory all the infaunal
samples were identified to the lowest taxonomic level as possible, counted and
weighted.
Five epifaunal replicate samples were collected at each site using 2 m beam
trawls during each of the five research cruises. Each trawl was conducted at a
constant speed (~2 knots per minute) and sampled an area of seabed of
approximately 400 m2. Once on board, the contents of the trawl were sieved
over 5mm mesh and all retained individuals were identified, counted and
weighed. In some cases, the very high numbers of some groups (e.g. brittle
stars, shrimps, and small fish) needed sub-sampling before counting and
weighting.
The raw abundance and biomass data for both the infauna (from the cores) and
epifauna (trawls) were scaled to values per m2. As some taxa were present in
both datasets, taxa which were more appropriately classed as infauna and/or
their densities were better estimated via a corer were classed as infauna and
removed from the trawl data. Accordingly, those taxa which were generally
considered as epifaunal (and their numbers and biomasses better estimated
using a trawl) were considered as epifaunal and/or their densities more
suitably estimated using a trawl were reported as epifauna.
