Biochemical composition of wild copepods, Acartia spinicauda and Oithona similis, from Parangipettai coastal waters in relation to environmental parameters.

Percentage composition of protein, lipid, carbohydrate and amino acids of copepods, Acartia spinicauda and Oithona similis collected from Parangipettai coastal waters were estimated following standard methodologies. Of the principal biochemical constituents, protein formed the major component followed bylipid and carbohydrate. Biochemical composition analysis of wild copepods indicated their nutritional rank. The ranges of protein, lipid and carbohydrate (%) contents (of A. spinicauda and O. similis) were 67.33-75.45; 12.42-16.58; 6.69-7.98 (Stn 1); 68.10-74.62; 12.65-17.81; 4.41-7.34 (Stn 2); 68.65-74.93; 14.55-17.69; 4.01-7.90 (Stn3) and 59.53-69.61; 10.76-17.68; 3.43-6.59 (Stn 1); 62.39-67.09; 10.26-15.65; 3.78-5.85 (Stn 2) and 59.57-67.60; 9.89-15.44; 3.71-5.72 (Stn 3) respectively. Totally 16 amino acids were observed in these wild copepods, with threonine, glutamic acid, alanine, aspartic acid, serine, valine and methionine as the dominant ones. The minimum and maximum values of atmospheric and surface water temperatures (degrees C), salinity (%), pH and dissolved oxygen (ml l(-1)) were 28.5-35; 28.7-34.2; 14.5-35.7; 7.4-8.6 and 3.0-7.2 respectively. The ranges (microM) of nitrate, nitrite, phosphate and silicate were 7.9-52.9; 0.6-9.6; 0.5-7.5 and 8.2-140.5 respectively. The results supported the view that protein may function as a metabolic reserve in copepods and that the availabilityof a constant supply of food may render large amount of lipid storage unnecessary in tropical copepods.