Inter-population differences in temperature effects on Engraulis ringens yolk-sac larvae

Abstract

ABSTRACT: Early life stages of Engraulis ringens were reared from hatch until yolk exhaustion. Weevaluated the effect of temperature on characteristics such as larval length and yolk volume at hatch,larval length at yolk absorption, duration of yolk-sac stage, yolk consumption rate and larval growthrate. Further, we determined the potential differences in these traits between populations located 13°of latitude apart (Antofagasta 23°S, Talcahuano 36°S). The results showed that egg size had an effecton the larval length at hatch, initial yolk volume and larval length at yolk absorption, since the val-ues obtained were always larger in larvae hatched from Talcahuano (from larger eggs) than fromAntofagasta (smaller eggs). These characteristics were also modified by the rearing temperature.Duration of yolk-sac phase, yolk consumption rate and larval growth rate until yolk exhaustionshowed high thermic dependence in both populations. However, these traits showed no differencebetween populations when larvae were reared at the same temperature in the range between 12 and20°C, despite their initial difference in egg size. When extrapolated from the environmental condi-tions in each nursery area (i.e. 15°C Antofagasta and 12°C Talcahuano), our results suggest that theanchoveta populations from Talcahuano compensate for their lower larval growth rates by increasingtheir initial egg and hatch sizes, as they are larger than Antofagasta larvae at the end of the yolk-sacstage. This increased larval length should enhance their chances of survival under adverse environ-mental conditions, such as high turbulence, lower temperature and lower food availability duringwinter, which is typical of the anchoveta southern spawning area.KEY WORDS: Anchoveta · Early life-history traits · Egg size · Growth · Latitudinal differences ·Temperature effects