Differences in meiofauna communities with sediment depth are greater than habitat effects on the New Zealand continental margin: implications for vulnerability to anthropogenic disturbance.

Studies of deep-sea benthic communities have largely focused on particular (macro) habitats in isolation, with few studies considering multiple habitats simultaneously in a comparable manner. Compared to mega-epifauna and macrofauna, much less is known about habitat-related variation in meiofaunal community attributes (abundance, diversity and community structure). Here, we investigated meiofaunal community attributes in slope, canyon, seamount, and seep habitats in two regions on the continental slope of New Zealand (Hikurangi Margin and Bay of Plenty) at four water depths (700, 1,000, 1,200 and 1,500 m). We found that patterns were not the same for each community attribute. Significant differences in abundance were consistent across regions, habitats, water and sediment depths, while diversity and community structure only differed between sediment depths. Abundance was higher in canyon and seep habitats compared with other habitats, while between sediment layer, abundance and diversity were higher at the sediment surface. Our findings suggest that meiofaunal community attributes are affected by environmental factors that operate on micro- (cm) to meso- (0.1-10 km), and regional scales (> 100 km). We also found a weak, but significant, correlation between trawling intensity and surface sediment diversity. Overall, our results indicate that variability in meiofaunal communities was greater at small scale than at habitat or regional scale. These findings provide new insights into the factors controlling meiofauna in these deep-sea habitats and their potential vulnerability to anthropogenic activities.

Two new species and a new record of Comesomatidae (Nematoda, Araeolaimida) from Southern Hikurangi Margin, New Zealand.

We describe two new species and provide one new species record of the family Comesomatidae from a submarine canyon habitat on the Southern Hikurangi margin, New Zealand. Vasostoma hexodontium n. sp. is characterized by having an amphideal fovea with three turns, buccal cavity with six teeth and gubernaculum with long and straight caudal apophyses. Sabatieria dispunctata n. sp. is characterized by the absence of cuticle punctations, large amphideal fovea with 4.5 turns, pharynx with posterior bulb, absence of pre-cloacal supplements, strongly arcuate and cuticularized spicules, simple gubernaculum with short caudal apophyses, and vulva opening directed posteriorly. Laimella subterminata Chen & Vincx, 2000, which was originally described from the Beagle Channel and the Magellan Strait (Chile), is recorded from the Southwest Pacific for the first time.