Oxygen and carbon isotopic values were measured on specimens from 17 samples from the Campbell Plateau and the S Tasman Rise. In particular, four podocopid ostracod genera were analysed: the in-faunalKrithe and die epifaunalFallacihowella, Poseidonamicus andBradleya. The stable isotopes proxies provided useful indications about the microhabitats, the diets and the temperature sensitivity of each tax-on. Additionally, different calcification rates and different microhabitats were claimed to explain the different isotopic signature of adults and juveniles of Krithe.
Statistical analyses were performed on the relative abundance in percentages of 73 species identified in 19 sediment samples. Both species (R-mode) and samples (Q-mode) were grouped by cluster analyses and detrended correspondence analyses (DCA) using the software package PAST (ver. 0.94).
Q-mode cluster analyses partially supported the observations made by previous authors that the ostracod specific thresholds are controlled by the water mass characteristics. Q- and R-mode detrended correspondence analyses, on the contrary, indicated that distribution patterns must be driven by factors other than the water mass characteristics. Seven assemblages are recognised and the characteristic or most abundant species are discussed for their ecological demands. Bottom topography, sediment type, CaC03 content, and flux of organic carbon interplay with the water mass characteristics creating a complex network of ecological gradients. Within each of the identified assemblages the species specific thresholds are not identical and often the range of the ecological gradients of the most abundant species do not include that of the characteristic species. Most likely, dynamics of co-occurring species take place which could involve Ostracoda and other benthic animals belonging to the same trophic groupings.