Distribution pattern of ichthyoplankton in El Rincón Shelf Region, Argentina

MÓNICA S. HOFFMEYER; FLORENCIA BIANCALANA; MARÍA C. MENÉNDEZ; EDUARDO R. TORRES

Espinho, Portugal

Simposio; I Plankton Symposium; 2001

Qualitative and quantitative ichthyoplankton and environmental data from a cruise in El Rincón coastal region during the beginning of November, 1993, were analyzed in the attempt to define the ichthyoplankton distribution patterns and to find the environmental factors acting on them. Principal components analysis (PCA) applied to eggs and larvae abundance data and clusters analysis (CA) of samples using Euclid distance and complete linking were performed. A multiple lineal regression analysis (MLRA) of abundance of eggs and larvae and zooplankton abundance (ZOO), salinity (SALT), temperature (TEMP), particulate organic carbon (COP), chlorophyll a (CLO) and phaeopigments was also carried out applying the stepwise method in the variables selection. Three first components from PCA accounted for 91.2 % of total data variance. According to the correlation between these three components and variables, the first component represented Scienidae eggs and larvae, P. signata eggs and E. anchoita larvae, while the second component represented B. aurea eggs and larvae. B. aurea and P. signata larvae were the most correlated ones, although negatively, with the third component. CA showed four sample groups, which had already been suggested by the analysis of components. MLRA selected models were: for eggs= -45,7788 + 1,017 ZOO + 11,2752 SALT and for larvae= 44,7 – 0.001 COP + 1,35 SALT + 0,7112 ZOO, with multiple determination coefficients (R2) of 0,482 and 0,601, respectively. Distribution patterns determined for eggs and larvae of different particular taxa were similar to those obtained for total ichthyoplankton. Similar dependence relations with environmental variables were also observed.