Vertical distribution, specific gravity, and free amino acids in anchoveta Engraulis ringens eggs under contrasting spawning habitat conditions

The present study determined whether maternally influenced early life history traits vary for anchoveta eggs spawned in 2 contrasting environments: off northern (Iquique 23°S) and off central Chile (Talcahuano 36°S). Using eggs collected in the field, we showed that free amino acid contents, specific gravity, and vertical distributions of eggs in the water column changed as eggs developed. Specific gravity correlated negatively with free amino acid content. At the inter-population level, differences were determined in free amino acid egg contents (higher in Iquique), specific egg gravity (lower in Iquique), and vertical egg distributions (shallower in Iquique). Specific egg density along with the seawater density distribution and vertical mixing must be taken into account in both areas to explain the observed vertical distributions, as depicted by different egg buoyancy models. Overall, the results of this study suggest that FAA might play a role in egg development, potentially modulating specific gravity and egg position in the water column. The observed vertical distribution of eggs at each location and their changes throughout the season seemed to benefit young offspring, allowing them to avoid layers of stressful conditions especially in northern Chile, where a layer of minimum oxygen concentrations occurs near the surface.