Effect of algal food and feeding schedule on larval growth and survival rates of the queen conch, Strombus gigas (Mollusca, Gastropoda), in Mexico

Abstract

The effect of algal diet and feeding schedules on larval growth (daily siphonal length increments) of the queen conch, Strombus gigas, was studied over a period of 20 days in laboratory culture. Experiments were conducted at 29±1°C. Conch veligers were reared at 275 larvae·l −1 in 4-litre disinfected containers. Larvae were fed Thalassiosira fluviatilis, Isochrysis aff. galbana and Tetraselmis suecica with fixed daily rations arranged in three different feeding schedules varying from low (500–10 000) to medium (1000–30 000) and high (2000–40 000) algal cells·larva −1·day −1. Larvae fed T. fluviatilis showed total mortality of larvae fed the low and high schedules. Larvae fed the low schedule of I. aff. galbana grew slower at an average rate of 23.71 μm·day −1 than those receiving the medium and high schedules with 29.97 and 30.70 μm·day −1, respectively. Nevertheless, no differences were found between feeding schedules for this same alga, when medium and high schedules were compared (Duncan=0.05). The fastest growth at an average rate of 36.92 μm·day −1 and the highest survival of 82% were found for larvae fed the high schedule of T. suecica, even when compared with the high schedule of I. aff. galbana. Results obtained showed a better nutritional value of T. suecica over the two other algal foods tested.