Abstract:
The bryozoan faunas of 104 sediment grab samples and 29 shore and shallow water collections from the northern Hauraki Gulf are described and illustrated. 175 species and subspecies are recognised, 23 of which are described as new and a further 8 recognised as new but not formally described owing to their poor state of preservation. One new genus, Maoricellepora, is proposed. The new species described are Conopeum zelandicum, Amphiblestrum remuliformis, Chaperiopsis uttleyi, C. browni, Beania huttoni, Caberea breviscuta, Celleporaria (Celleporaria) haurakiensis, Macricellepora parva, Urceolipora hyalina, Conescharellina depressa, Sphaeropora granulata, Haswellina triavicularis, Smittoidea tawharanuiensis, Diastopora haurakiensis, D. kotahirau, D. maangainui, Tubulipora haurakiensis, Hastingsia maoriana, Crisia zelandica, Hornera aotearoa, H. gracilis, Crisina haurakiensis and Disporella bicuspis, and the new subspecies is Beania inermis zelandica. The Anascina is subdivided into superfamilies based largely on the 'Divisions' of previous authors.
The main environmental factors in the northern Hauraki Gulf are summarised and their effect on the bryozoan fauna discussed. The substrate preferences of some species are recognised.
The distribution and diversity patterns of the bryozoan fauna are examined, the greatest numbers and highest diversities being in the coarse sediments, the faunas of the fine sands and muds being sparse.
The eschariform and vinculariiform growth types are redefined and the assemblages analysed in terms of zoarial form.
Differences from some previous investigations of bryozoan growth form distributions are the absence of reteporiform species from shallow water, and the presence in shallow water of vinculariiform species in which the outer walls have been strengthened by secondary calcification or the branches are anastomosing.
A brief discussion is given on the use of Bryozoa in palaeoenvironmental analysis in the light of this and previous studies on bryozoan distribution.