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Marine Ecology Progress Series

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MEPS 166:237-245 (1998)  -  doi:10.3354/meps166237

Daily larval growth and RNA and DNA content of the NW Mediterranean anchovy Engraulis encrasicolus and their relations to the environment

Alberto García*, Dolores Cortés, Teodoro Ramírez

Instituto Español de Oceanografía, Centro Oceanográfico de Málaga, Puerto Pesquero s/n, E-29640 Fuengirola, Málaga, Spain

Anchovy Engraulis encrasicolus larvae, collected from 2 different sites in the Western Mediterranean Sea (the Gulf of Lions and the Catalán Sea), were analyzed for daily growth rates and RNA and DNA content. An exponential function describes the growth pattern. The larvae were shown to have a growth rate of 0.56 mm d-1 at 8 mm (standard length). Anchovy larvae from the Gulf of Lions showed higher daily growth rates than larvae from the Catalán Sea. In accordance, sagittal size, measured in terms of otolith area and radius, of larvae from the Catalán Sea were smaller than those of larvae from the Gulf of Lions. RNA/DNA ratio ranged from 1.09 to 7.79, and the mean RNA/DNA ratio was 4.49. Anchovy larvae from the Gulf of Lions were shown to have a higher slope in the RNA (µg larva-1) versus DNA (µg larva-1) relationship than larvae from the Catalán Sea. This indicates that the former were in better condition. However, due to the high variability of the RNA/DNA ratio, no significant differences in RNA/DNA ratio were found between the 2 areas. A preliminary study of the relationship between environmental factors and the RNA/DNA ratio was performed for each region. The RNA/DNA ratio of larvae from the Catalán Sea correlated negatively with temperature and positively with relative fluorescence and organic matter, while in the Gulf of Lions there was a positive correlation with temperature and no relation with relative fluorescence or organic matter.

Anchovy · Larvae · Growth · Otolith · RNA · DNA · Condition

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