Introduction
Holothuria floridana has become one of the most promising sea cucumber species for aquaculture in Latin America for its easy rearing in captivity, high resistance to variations in the water-physicochemical conditions, and widespread broodstock availability when compared with Isostichopus badionotus, the most expensive species in the area. However, further research is needed, especially regarding developing diets and optimizing rearing conditions to massify its cultivation under diverse conditions (inland and coastal marine environments). This study aims to develop new diets and protocols for cultivating H. floridana in inland facilities.
Methods:
Four experiments were conducted. The first one (A) compared three different diets containing a mix of ingredients, of which the only ingredients that varied were: diet E, containing 1g of spirulina per dose; diet M, with 0.5 g of spirulina and 0.5 g of yeast, and diet Y, with 1 g of yeast. The second experiment (B) dealt with densities (15, 30, and 46 org/m2) using 6-month-old juveniles produced in situ that were fed 40 ml of a seaweed meal/fish feed/enricher blend and 50 ml of pretreated mud from a mangrove lagoon close to the experimental facilities. For the third experiment (C), the densities were changed accordingly with the growth of the organisms, evaluating 15, 26, and 38 org/m2, and the feed ration was proportional to the number of animals per tank (40, 70, and 100 ml, respectively). In the last experiment (D), we selected the average between the best-performing densities (23 org/m2), in this case, evaluating four feeding rates equivalent to 25, 50, 75, and 100% of the total biomass/week. For every experiment, sea cucumbers were weighed weekly; water temperature was kept at 26 ±1 ºC; animals were fed three times a week, using 76 L tanks with a base area of 0.26 m2 with four replicates for every experiment.
Results
The mixed spirulina/yeast diet resulted in higher growth and survival, followed by the one containing only yeast. High levels of spirulina seem to have detrimental effects on survival and growth. For the second set of experiments, densities of 15 and 30 org/m2 tend to present better growth, up to 200 %, after a month (15 org/m2), possibly due to insufficient feed availability for all the organisms at the 46 org/m2 density. In the second experiment, all treatments behaved similarly until the end, where the lower density performed better. In the third experiment, with equal density (23 org/m2) higher feeding rates outperformed the lower feeding rates initially; however, 50% to 75% of the weekly weight performed better overall in the end, possibly due to the accumulation of uneaten organic matter in the tank, which led to the appearance of fungi and bacteria in some replicates in both experiments C and D.
Conclusion.
These results prove that H. floridana is an excellent candidate for inland cultivation, where external feeds are necessary, and cultivation area can be a limiting factor. These experiments demonstrated that it is possible to design easily sourced and cheap diets and that the species can resist relatively high densities without significantly reducing growth. We recommend including yeast on the feeds, potentially enriching with low spirulina doses, and using an initial density between 15 to 30 org/m2 and a feeding rate of 50 to 75 % of the stoking biomass per week to produce the best growth performance.Figura SEQ Figura \* ARABIC 1. A. Crecimiento. B. Supervivencia