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One of the major problems involved in the controlled cultivation of Patagonian red octopus (Enteroctopus megalocyathus) is its long embryonic period ranging between 150-176 days, after which the hatching of planktonic paralarvae is achieved. The effect of temperature on the incubation of E. megalocyathus eggs was studied with the aim of establishing if a temperature higher than 12°C is effective to accelerate the embryonic development without altering their morphological and physiological conditions. Fertilized eggs obtained under controlled conditions at 11°C AE 0.1 were randomly distributed in 12 water baths of 30 L at 4 temperatures: 12, 14, 15 and 16°C AE 0.1°C. The experiment lasted until egg hatching occurred.The embryo growth rate was accelerated at 15-16°C, so the time spent in embryonic development can be reduced in 15% when compared with embryo development obtained from eggs incubated at 12°C. The embryos showed no significant differences in the final survival and were morphometrically similar in all stages of development at all temperatures. The increase in temperature from 12 to 16°C, even if it allowed a better growth, had high metabolic costs for embryos of E. megalocyathus. The activities of lipases and proteases were affected by interaction between temperature and the embryo stage, with high lipase activity observed in embryos of stage XV incubated at high temperatures and the highest levels of trypsin and chymotrypsin in stage XX at 14°C. The results suggest that 15°C could be the limit temperature to increase growth.

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The limited success reported in the paralarval culture of merobenthic octopus is mainly attributed to nutritional problems. This study aimed to determine the effect of live diets on the paralarvae performance during the first 30 days after hatching (DAH). The paralarvae were grown under different treatments: starved (STV) as negative control or fed four diets: Artemia sp. enriched with microalgae (ANCH), Artemia enriched with a commercial enrichment (AOG), Artemia enriched with microalga + commercial enrichment (AMIX) and king crab zoea (ZKC). The paralarval growth and survival were affected by the dietary treatment, with significant higher growth in ANCH and AMIX. STV showed 100% mortality at day 27, whereas all diets resulted within a range from 20% to 33% survival. The endogenous protein and lipid reserves were utilized in all treatments. The 22:6n-3/20:5n-3 ratio increased up to 16% during the experimental period. Alkaline protease activity tended to increase in paralarvae fed ANCH, AOG and ZKC over the first 13 DAH; however, this effect was not observed in trypsin nor chymotrypsin activities. The leucine aminopeptidase activity (LAP) was not affected by the dietary treatment, while alkaline phosphatases increased only at 13 DAH in paralarvae fed ANCH. Indicators of the nutritional status of paralarvae are discussed.