An analysis of temporal variability in abundance, diversity and growth rates in the coastal ichthyoplankton assemblage of South Georgia (sub-Antarctic)

Data from a seven-year (2002-2008) ichthyoplankton sampling programme in Cumberland Bay, South Georgia, sub-Antarctic (54.25^oS, 36.5^oW) were analysed to assess temporal changes in larval fish diversity and abundance. Larvae of twenty two species, representing nine families, were identified although three, Krefftichthys anderssoni (Myctophidae), Lepidonotothen nudifrons/T.hansoni (Nototheniidae) and C. gunnari (Channichthyidae), dominated abundance in all years. Significant seasonal and interannual differences in the larval fish assemblage were revealed by multivariate analyses (nMDS, ANOSIM, SIMPER). Multiple regression analyses indicated that larval abundance within Cumberland Bay was not significantly correlated with local SST or primary productivity.  Estimates of larval growth are provided for 5 abundant species. Considerable inter-specific differences in relative larval growth rate were recorded but interannual variability within species was small. However, in C. gunnari, multiple larval cohorts, representing a protracted spawning season, were observed to grow at different rates and this may be related to temperature and /or food availability. A comparison with historical growth data from South Georgia suggests there has been little change in growth rate for the main species over the last three decades.