Smith Achilleos Gordon: Distribution patterns of shelf bryozoans around southern Aotearoa New Zealand
Description
The area of southern Aotearoa New Zealand, from Fiordland, Foveaux Strait and Otago southwards to Snares Platform is a well-known bryozoan hotspot, with fewer species known from the shelves around Auckland and Campbell Islands further south. Over 350 bryozoan species have been reported from this region, principally from monographs in the 1980s, augmented by a shelf dredging programme conducted by the University of Otago. We have, to date, 158 University of Otago and 71 NIWA stations in the region from 44°S to 53°S latitude, 165°E to 172°E longitude, in water depths ranging from 6 to 1003 m. A list of 359 bryozoan species was collated from 229 stations, based on published and unpublished distribution data. The 43 commonest species (15 occurrences) were mapped using ArcGIS® Pro and grouped into four common distribution patterns. Accurate distribution information allows for active conservation of these small but important sessile invertebrates, via habitat protection and management of bottom disturbance. Here we provide excel spreadsheets with station localities (Table 1), and the species: station matrix (Table 2) as well as the distribution maps for all 43 common and widespread species.
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Between 2008 and 2022, 241 bottom samples were collected by the University of Otago Dredging Programme (UO DP) using a beam trawl deployed from the RV Polaris II. The dredging programme includes, to date, 14 different cruises around Aotearoa New Zealand with the majority (158) of stations located south of 44°S (Fig 1, Supplementary Data Table 1). Upon collection, samples were briefly described on board and both living and dead specimens were collected; in addition, bulk reference samples were preserved in 99% molecular-grade ethanol. Additional bryozoan samples were retained dry. Species identification was carried out at the Portobello Marine Laboratory after each expedition and by later visitor researchers who worked with the material. Samples were stored at Portobello Marine Laboratory, Dunedin, Aotearoa New Zealand. A matrix of species and stations was created based on the work of Achilleos et al. (2019, 2020), and updated to include all species found in southern New Zealand (Supplementary Data Table 2). Stations north of 44 °S and those with no bryozoans were discarded, so that 122 Otago stations with bryozoans remained for analysis. From these, 43 species (or species complexes) were identified as common, occurring at more than 15 stations. For these species, presence data from 71 NIWA stations south of 44° S were also included (Gordon 1986, 1989). In total, 229 stations were included in the final dataset (see Supplementary Data Table 2). Distributional data were mapped using ArcGIS® Pro.