| Abstract |
Larviculture still represents the most important stage on fish production. Larvae survival and growth are correlated with the rearing parameters, such as temperature, stocking density, food supply, light intensity, water turbidity, use of green water, etc. Particularly, the use of microalgae in the rearing medium is a common procedure, nowadays, since it positively influences the survival, growth and development of most farmed fish larvae. However, quite scarce information exists regarding the potential effect of microalgae on larval foraging behavior. In addition, whether turbidity created by microalgae or equivalent water turbidity opposed to clear water medium affect feed intake during early developmental stages of fish is yet to be explored.
We investigated: a) Quantification and analysis of larval foraging behavior under three different rearing mediums b) larvae foraging pattern towards live feed along the developmental stages, and c) the growth rate. Two successive experiments were conducted under fully-controlled laboratory conditions. A total number of 105 sea bream eggs were used in this study, equally distributed to nine experimental tanks (5000eggs/tank/experiment). In the 1st experiment, three rearing mediums were tested in triplicates: Phytoplankton Medium (PM), consisting of Chlorella minutissima, Diatom Medium (DM), consisting of diatom’s powder solution and Clear water Medium (CM). In the 2nd experiment, DM was replaced by Chlorophyl Medium (ChM), which consisting of chlorophyll powder solution.
Larvae activity in tanks was being recorded twice every day in the 1st and three times per day in the 2nd experiment. Recordings were focused on the feeding time, where live feed (Brachionus plicatilis (Trochozoa) and Artemia sp. nauplii (Crustacean) were provided. Exceptionally in the second experiment, small amount of moisture was provided. Further, profile measurements regarding the water quality in tanks was performed every week to ensure stable conditions for larviculture.
From the results obtained, it can be concluded that a) the foraging behavior alters in relation with the developmental stages of sea bream larvae, b) the number of attacks was associated with the rearing medium and c) growth rate varies within the three rearing mediums (in each experiment).
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Sea bream (Sparus aurata) larvae foraging behavior under different rearing mediums
