La temperatura como factor de variabilidad en el desarrollo y morfología de larvas zoeas de Acanthocyclus hassleri Rathbun (Decapoda, Brachyura, Atelecyclidae) cultivadas en laboratorio

Abstract

Zoeae larvae of A. hassleri were reared at 10, 17 and 20°C, evaluating their survival, duration of larval life, larval size, sizes of different larval structures and morphometric proportions among structures with respect to larval size. Larval development of A. hassleri included four zoeal stages (ZI-ZIV) and one megalopa. The highest mean zoeal survival rate was 95.2% at 20°C in ZIV, decreasing to 13.2% in megalopae. Time of zoeal developmment fluctuated between 80.2 ± 3.2 d at 10°C and 28.2 ± 0.9 d at 20°C. The largest larval sizes were reached by ZI at 20°C, and ZII-IV at 17°C. Growth in size of the rostral spine, cephalothorax, abdomen and telson were directly proportional to culture temperature; growth of the dorsal spine, antenna, and both maxillipeds were inversely proportional to culture temperature. Morphometric proportion values between the rostral spine and abdomen remained constant; for céphalothorax and telson, the proportion disminished in stages ZIII and ZIV; those of the rostral spine, dorsal spine, antenna and both maxillipeds were significately higher at 10°C than at 17 and 20°C from the ZII stage onward. Results suggest a high capacity for thermal resistence in the zoeae of A. hassleri but not in its' megalopae. This capacity of the zoeae represents a high level of morpho-adaptive plasticity to temperature, suggesting a model of morphological plasticity associated with the culture temperature.