Abstract
Deep-sea meiofaunal communities vary at a range of spatial scales. However, identifying which scale(s) account for most of the variability in deep-sea communities remains difficult, as few studies have been designed in such a way as to allow meaningful comparisons across more than two spatial scales. Moreover, deep-sea studies have largely focused on particular (macro) habitats in isolation, with few studies considering multiple habitats simultaneously in a comparable manner. In the present study, meiofaunal and nematode community attributes (abundance, diversity, community structure and trophic structure) were investigated at different spatial scales (sediment depth (em), habitat (slope, canyon, seamount, and seep: 1-- 100 km), and region (100-10000 km)) in two regions on the continental slope of New Zealand (Hikurangi Margin and Bay of Plenty), while accounting for the effects of water depth (700, 1000, 1200 and 1500 m). Nematode species new to science encountered during sampling on the continental margin of New Zealand were also described. A consistent pattern for each meiofaunal community attribute was observed. The greatest variability was found between sediment depth layers and between regions, which explained 2-4 times more variability than habitats. Meiofaunal abundance and diversity were higher at surface than subsurface sediment. High abundance of meiofauna was also found in the higher productivity region of Hikurangi Margin than in the Bay of Plenty region, but not diversity, which was slightly higher in the Bay of plenty region. The variability pattern among spatial scales was not the same in each region. In the Bay of Plenty region, nematode diversity, community structure and trophic structure consistently showed increased variability from habitat and water depth to sediment depth. However, no consistent pattern was observed in Hikurangi Margin. The findings in this study suggest that meiofaunal community attributes are mostly influenced by sediment characteristics and food availability, but that disturbance (fishing activity and bioturbation) also accounts for some of the variability. These findings provide new insights into the relative importance of processes operating at different spatial scales in regulating meiofaunal communities in the deep-sea, and their potential vulnerability to anthropogenic activities. Two new species and one new species record of the family Comesomatidae from the Hikurangi Margin were described: Vasostoma hexodontium n. sp., Sabatieria dispunctata n. sp., and Laimella subterminata Chen & Vincx, 2000. A total of 159 species have been recorded/described from the New Zealand region, of which 37% are deep-sea species. This study improves understanding of meiofaunal biodiversity and their distribution patterns on the New Zealand continental region, which will help underpin effective management of New Zealand's continental margin communities in the future.