Macrobenthic assemblages of the continental shelf and upper slope off the west coast of South Island, New Zealand

Benthic macrofaunal samples were taken at 30 stations on the continental shelf and upper slope (32–1120 m) off the west coast of South Island, New Zealand, southeastern Tasman Sea (c. 41–43° S, 169–172° E). The area receives a high input (increasing southward) of river‐borne sediment, so fine‐grained sediments characterise the shelf and uppermost slope. Most samples were dominated by polychaetes (mean of 36% of individuals), with bivalves and amphipods usually the next most abundant major taxa (mean of c. 10–11 % of individuals). Polychaetes, molluscs and peracarid crustaceans together accounted for c. 11% of species collected. Four main station groups were identified by multivariate analysis: (1) 4 stations at 32–51 m on silty sand characterised by Sthenelais cf. chathamensis, Nephtys sp., Aglaophamus macroura, Paraprionospio sp., Ampharete kerguelensis, Diplocirrus sp. (all Polychaeta), Austrofusus glans (Gastropoda) and Maorimactra ordinaria (Bivalvia); (2) 12 stations at 87–297 m on sandy mud characterised by Aglaophamus verrilli, Lumbrineris ?brevicirra, Paraprionospio coora, Diplocirrus sp. (all Polychaeta), Poroleda lanceolata (Bivalvia) and Ampehsca chiltoni (Amphipoda); (3) 3 stations at 195–248 m on sand at the northern end of the study area where characterising species were Otionella affinis (free‐living Bryozoa) and Chloeia inermis (Polychaeta); and (4) 10 stations at 477–1120 m on sandy mud where good discriminators were Apseudes diversus (Tanaidacea) and Ophiozonella stellamaris (Ophiuroidea). Mean biomass estimates for the four station groups were 79, 40, 35, and 6 g wet wt m^‐2 respectively. Ordination of polychaete genera indicated similarities between shallow (< 500 m water depth) west coast samples and directly comparable samples from the Chatham Rise east of the South Island, whereas deeper (> 500 m) west coast samples were more disparate.

Keywords:

• benthos
• fauna
• assemblages
• biomass
• continental shelf
• continental slope
• bathyal
• New Zealand
• South Island
• Tasman Sea
• Chatham Rise

Notes

Department of Marine Science, University of Otago, P.O. Box 56, Dunedin, New Zealand.