DENSITY OF ROUND SARDINE SARDINELLA AURITA EGGS, ZOOPLANKTON ABUNDANCE AND HYDROGRAPHY IN THE ARAYA PENINSULA AND SOUTH OF MARGARITA ISLAND, VENEZUELA

Abstract

During 18 months (October 2007 - March 2009) the density of eggs and larvae of round sardine Sardinella aurita, the abundance of mesozooplankton and hydrography were studied in three stations located south of Margarita island (Coche, Cubagua and Macanao) and three stations at the Araya Peninsula (Guaca, Chacopata and Araya). Nocturnal horizontal hauls (20 minutes; 15-20 m depth) of plankton (net diameter 1.0 m; net length 2.5 m and mesh size 400 μm) and water samples (surface and 25 m) were collected to determinate temperature, salinity and dissolved oxygen. Eggs of sardine were found during all study months; in the Araya Peninsula the mean density ranged between 2.51 and 5.19 eggs/ m3 and ranged between 5.22 y 7.06 eggs/m3 at the south of Margarita Island. The highest density (47.51 eggs/m3) was found at Coche. The abundance of sardine eggs was minor than between 2002 and 2004 at the east of Margarita. The monthly mean density of total zooplankton ranged between 170.63 and 1032.8 ind/m3; the dry weight between 2.53 and 7.32 mg/m3 and the settled volume ranged between 0.26 and 0.38 mL/m3. The highest abundances of zooplankton and sardine eggs were found at Coche and Cubagua stations. The hydrography is discussed; the temperature values at the surface and at 25 m depth (means 26.5 and 24.9 °C) are considerate high and comparable to mean temperatures of previous years (2005 to 2007) and possibly affecting sardine abundance in the region.