Environmental effects on the spatial variability of the ichthyoplankton from southern Chile during November 2005

The distribution and abundance of ichthyoplankton from southern Chile (41-45 degrees S) during November 2005 were analyzed, in relation to the oceanographic features of the water column (temperature, salinity, stratification). During the sampling period, 44.606 fish eggs and 2.016 fish larvae were collected, belonging to 28 taxa. Early life stages of small pelagic fishes dominated the plankton samples, with mean densities of 14,000 eggs 10 m(-2) of anchovy (Engraulis ringens) and > 100 larvae 10 m(-1) of clupleids. Multivariate analysis showed the conformation of two groups of stations, one associated to deeper fjord areas, with strong vertical gradients of temperature and salinity, and higher stratification. The other group was associated to the shallow and well-mixed eastern border of Chiloe Island. In areas with strong stratification (i.e., higher Brunt-Viiisdla frequency, N-2), significant higher densities of pelagic and mesopelagic fish eggs and larvae were collected (i.e., Strangomera bentincki, Maurolicus parvipinnis). Comparing these results with an oceanographic cruise carried out 10 years before in the same area (October 1995), changes in the ichthyoplankton composition were detected; this may be caused by potential differences in the marine fish species which utilize fjords and channels of southern Chile as spawning and early nursery zone.