Sediment core collection and processing- Several sediment
push-core samples were taken from each push-core sampling location
; one or two push-cores were allocated for CHN and grain size analysis, and two to four for macrofauna analysis. Upon recovery of the ROV, push-core samples
were maintained at 5 C until processed. The top 3 cm
of 11 push-cores was subsampled for grain size and
CHN analyses. Sediment from the remaining 20 cores was sieved
to remove organisms by gently washing the top 5 cm from each core through a 0.3 mm mesh sieve using chilled seawater. Organisms were preserved in a 4%
formaldehyde solution for 1–3 days, and then stored
in 70% ethanol. Qualified experts subsequently identified macrofauna
to the lowest practical taxonomic unit.