The articulated bryozoan genus Cellaria in the southern Zealandian Region: distribution and associated fauna

Abstract

The Zealandian Region centred on New Zealand has the highest diversity of Cellaria species in the world, with three described and 11 undescribed living species. This study assesses their distribution in relation to environmental parameters and characterizes the associated bryozoan fauna in the Southern Zealandian Region based on specimens collected in the years 1911–2018. Cellaria specimens stored in collections in New Zealand were identified to species level, and their metadata were combined with that in the published literature to provide a database for analysis. Distributional data were mapped and assessed in relation to environmental factors: surface chlorophyll-a, sea-surface and seafloor temperature, and substratum type. The bryozoan fauna co-occurring with Cellaria was recorded and characterized according to community assemblage composition. Of the 14 Cellaria species, C. immersa and C. tenuirostris are the most dominant in the southern Zealandian region. Presence/absence records showed that Cellaria species mostly occur at sites with relatively low productivity (0.10–0.99 mg m−3) and relatively high seafloor temperatures (13–14 °C). Sand was identified as the main textural component of the substratum where Cellaria was found. The ability of Cellaria species to colonize soft sediments is of ecological importance in mid-shelf environments where hard substrata are uncommon. The associated bryozoan fauna comprises common elements of bryozoan assemblages and their reef formations around the world and is characterized by species having an erect-rigid colony growth form. The present results can contribute to future ecological analyses using Cellaria species globally as key elements for other bryozoan faunas.