Effect of biotic and abiotic factors on the biochemical composition of wild eggs and larvae of several fish species

Abstract

The aim of this study is to establish possible associations between temperature, salinity and egg and larval abundance, and the biochemical composition of wild ferthsed eggs and larvae of marine fish species. Eggs and larvae of the most abundant species at each station at the time of sampling were collected during 2 surveys carried out from 25 March to 14 Apnl 1995 (MPH-95) for collecting eggs and from 30 May to 16 June (SEFOS-95) for collecting larvae. Both surveys were carried out on the N-NW coast of the Iberian Peninsula. Egg size, egg abundance, egg stage, temperature and salinity explained a small variance in the high variation observed within and between stations in protein, carbohydrate and lipid content of the eggs in both Trachurus trachurus and Scomber scombrus. Conversely, protein, carbohydrate and lipid content of larvae in Sardina pllchardus, Engraulis encrasicolus and T trachurus seemed to vary according to either larval body length, temperature, salinity a n d o r larval abundance. Protein, carbohydrate and lipid content increased as larval body length increased for the 3 species. However, a percentage of lipid and protein in the larvae of the 3 species varied according to prevailing buoyancy conditions. An increment of larval lipid percentage and a reduction of larval protein percentage was observed as temperature increased and salinity decreased, the opposite case causing an increase in protein percentage and a decrease in lipid percentage of the larvae. This trade-off between protein and lipid production is interpreted as a mechanism to achieve optimal larval buoyancy.

Biochemical composition and condition in anchovy larvae Engraulis encrasicolus during growth

“…This has been observed in other studies of Engraulis encrasicolus (Guisande et al 1998) and in studies of other fish larvae (Ehrlich 1974a,b, Cetta & Capuzzo 1982. However, the mean carbohydrate content established in the present study (2.3 to 8.5% of OM) was lower than that reported for anchovy by Guisande et al (1998) (mean =16.5% of PCL), but was very similar to that obtained for herring (3.4 to 4.6% of DW), another clupeoid (Ehrlich 1975).…”

Egg and larval amino acid composition as indicators of niche resource partitioning in pelagic fish species

“…An increment of the larval lipid percentage and a reduction of the larval protein percentage was observed as water density decreases (Guisande et al 1998); whereas when water density is higher, the percentage of protein is higher than the lipid in the larvae.…”

“…Carbohydrate seston content was measured by the phenol-sulphuric acid method (Dubois et al 1956) and the lipid seston content was determined using the sulfophosphovanillin method (Zöllner & Kirsch 1962). Protein, carbohydrate and lipid analyses of eggs and larvae are further described in Guisande et al (1998).…”

“…Egg biochemical composition in pelagic fishes is species specific (Guisande et al 1998), although seasonal and spatial variations within each species have been observed (Guisande et al 1998. These seasonal and spatial variations in the egg biochemical composition are mainly due to adult diet and/or parental strategies.…”

“…Both lipid and amino acid composition of the eggs are affected by changes in adult dietary composition (Silversand et al 1996, Pereira et al 1998. Parental strategies could also lead to changes in egg biochemical composition as a mechanism to maximise egg and larval survival under the prevailing habitat conditions: prey availability, temperature, salinity, etc (Brown & Taylor 1992, Nissling & Vallin 1996, Guisande et al 1998.…”