Polychaete Distribution on the Chatham Rise, Southwest Pacific

Abstract

Macrobenthic samples .were collected along 3 north-south transects at 244-1394 m depth across the Chatham Rise, eastern New Zealand, to examine the distribution of polychaete assemblages in the region of the Subtropical Convergence (STC). Two main assemblages were identified: at 244-663 m depth occurring mainly on the crest of the Rise, and at 802-1394 m on the slopes of the Rise. Community composition differed,. however, between the northern and southern slopes of the Rise. The southern slope supported higher faunal densities and a greater proportion of surface deposit feeders. This latitudinal difference may reflect variability in organic flux across the STC.

Comparative biomass of sediment benthos across a depth transect, Chatham Rise, Southwest Pacific Ocean

“…Meiofauna samples are generally dominated by nematodes, followed by harpacticoid copepods, and nauplii (Vanaverbeke et al 1997, Soltwedel 2000, Vanhove et al 2004 1991, Paterson & Lambshead 1995, Probert et al 1996, Smith & Demopoulos 2003. Total (meio-and macrofaunal) biomass decreased with increasing water depths on both sides of Chatham Rise, but this decline was more pronounced on the northern slope, reflecting different levels of productivity on either side of the crest and the Subtropical Front.…”

“…through macrofaunal bioturbation; Witte et al 2003b), resulting in a pool of labile organic carbon that is available at greater depths and over longer time scales than those immediately associated with episodic flux events (Nodder et al 2007). The high proportion of high-quality food available at shallow sites and on the southern slope supports consistently greater benthic productivity, as evident in higher faunal biomass and sediment community oxygen consumption rates (Probert & McKnight 1993, Probert et al 1996, Nodder et al 2003, 2007, Grove et al 2006.…”

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

“…The only other continental margin area of New Zealand where the polychaete fauna has been sampled in comparable detail is the Chatham Rise (Probert et al 1996), a relatively broad submarine high at bathyal depths east of the South Island. Among the common species recorded both on the Chatham Rise and in the present study were Sigalion ovigerum, Labiosthenolepis laevis, Aglaophamus verrilli, Hyalinoecia tubicola, Kinbergonuphis cf.…”

“…But despite the importance of polychaetes, infaunal studies may not always take adequate account of them. McKnight's (1969) survey of New Zealand shelf assemblages was based primarily on conspicuous molluscs and echinoderms, and the only extensive study to have focused on polychaete assemblages of the New Zealand continental margin is of a bathyal region (Probert et al 1996). Information on the structure and distribution of polychaete assemblages in the New Zealand region and their relationship to environmental variables is consequently still very limited.…”

Feeding habits and niche separation among the deep-sea chimaeroid fishes Harriotta raleighana, Hydrolagus bemisi and Hydrolagus novaezealandiae

“…The STF is a region of heightened primary productivity (Murphy et al 2001), supporting an abundant mesopelagic biomass, particularly on the west side of the rise (McClatchie & Dunford 2003). Chatham Rise and the STF act as an area of pelagic (Robertson et al 1978, Bradford-Grieve et al 1999, demersal (Bull et al 2001, Leathwick et al 2006) and benthic (Probert et al 1996, McKnight & Probert 1997, Nodder et al 2003) ecosystem discontinuity. The pronounced ecosystem changes across the STF are likely to influence both the distribution and diet of chimaeras through variations in environmental conditions and prey availability.…”