This thesis was conducted under the auspices of the Southern Ocean Continuous Plankton Recorder (CPR) Survey. The research conducted had the dual aims of providing baseline data for this long-term monitoring programme and providing the first detailed analysis of zooplankton communities and distribution patterns in the Southern Ocean south of Australia. Data were principally collected between ... October 2001 and March 2002, during five voyages. As a primary step I investigated the sampling characteristics of CPR, and assessed the utility of the CPR as a long-term monitoring apparatus in the Southern Ocean. Given the shallow sampling depth of the CPR (~10.5m), a major requirement of this calibration was quantification of the fine-scale vertical distributions zooplankton. This was done through direct comparison of CPR samples with depth integrated NORPAC net hauls. The CPR-NORPAC comparison identified the component of the zooplankton sampled by the CPR and provided a means for comparison between past and present data sets. As a final component of this calibration, it was demonstrated that the CPR was effective at identifying biogeographic boundaries.
An essential requirement for the identification of long-term ecological change is baseline data on natural ecosystem variability, particularly seasonality. Therefore, after calibration of the CPR the two fundamental components of spatial and seasonal variability were investigated. Firstly, the fine-scale horizontal structure of zooplankton communities was quantified from a 1170 nautical mile transect, along the 140oE meridian, spanning all of the major oceanographic zones south of Australia. Applying multivariate analyses a unique community zonation was identified which was strongly related to the complex oceanographic environment, characterised by multiple branches of the major fronts. The seasonal component of temporal variability was investigated separately in two major and distinctly different regions, the Seasonal Ice Zone and the Sub-Antarctic / Polar Frontal Zone. Multivariate analyses were used to quantify seasonal changes in species composition, Bray-Curtis dissimilarity, species densities, and the proportional contribution of species to communities. The spatial and temporal variation of zooplankton community structure was discussed in the light of environmental controls, species' vertical distributions, population cycles, and ecosystem functioning. Finally,the application of these data to long-term monitoring was discussed, and recommendations made for future research.
The fields in this dataset are:
Segment Length (nautical miles)
Sea Surface Temperature