Epibionts affect the growth and survival of Argopecten purpuratus (Lamarck, 1819) cultivated in Samanco Bay, Peru

Argopecten purpuratus, a mollusk very cultivated in Peru, is a species whose ecological relations with respect to the epibionts that colonize it are not well known. For that reason, the objective of this research was to determine the effect of epibionts on valvar growth, total weight, gonad weight, adductor muscle weight, and survival of this cultured species in Samanco Bay. Four lanterns of 2 m and 10 floors were placed with 25 organisms, of 7 cm each, per floor, in two treatments: with epibiont removal (T1) and without removal (T2). The data was obtained after harvest, and the epibiont species on the right and left valves were identified and quantified in T1 and T2. In addition, the Absolute Growth Rate (AGR) was calculated for the meristic records, and the t Student test was applied to compare averages. Furthermore, mortality was recorded at harvest. The analyses allowed the identification of 43 epibiont species, 3 of them endolithic. The greatest biomass is of filter feeders: 70.1% in T1 and 90.9% in T2, and concentrated in 4 species, with limited development in T1. The biomass on the right valve at T1 and T2 represented 80.7 and 151.8% of the weight of the organism, respectively, and on the left valve 89.3 and 95.1%. All Absolute Growth Rates at T1 were higher than at T2, although without statistical significance. Mortality at T1 and T2 was negligible. This research has determined that the epibionts S. patagonicus, C. intestinalis, Hidroydes sp., and B. neritina, qualified as engineered species, are the predominant species on A. purpuratus in suspended cultures. Likewise, treatments with epibiont removal showed a lower development of these and 39 other associated species of lesser importance in terms of number and biomass. Our results allow us to infer that the development of epibionts can generate important stress in A. purpuratus, resulting in losses in the profitability of companies dedicated to this activity.