Experimentació en el cultiu de juvenils de nàiade allargada (Unio mancus Lamarck 1819) en condicions de laboratori

Abstract

Freshwater mussels (Mollusca, Bivalvia, Unionoidea) are one of the most threatened animal groups in Catalonia. Therefore, artificial culture establishes itself as a very important tool for their conservation. LIFE Potamo Fauna works for the conservation of freshwater mussels in Girona’s rivers from a captive breeding program carried out in three steps: obtain glochidia from breeding females, infestation of host fish and breeding and fattening of juveniles. The aim of this paper is to understand what is the best rearing and feeding strategy of juveniles mussels Unio mancus Lamarck, 1819 in the laboratory from growth and survival values of two differents breeding methods. In the first experiment juvenile were feed with three different diets (based on combinations of algae and detritus) and five different food doses and put inside glass containers with 500 ml of water during a period of 40 days. In the first 15 days, results shown a major growth of juveniles in response to a diet based on different algae: Nannochloropsis gaditana, Tetraselmis chuii and Phaeodactylum tricornutum. However, high mortality due to uncontrollable external factors, make impossible to know if this results occur along experimental days. Feeding juveniles with detritus, however, decrease growth values. In the second experiment we breed juveniles in a closed aquaculture system with three different treatments based on water recirculating speed (high, low or null) and with the same kind of diet. Treatments with high and low recirculation shown major mortalities in 40 days due to the effect of both the recirculation of water and the aeration. We determined that the best way to breed juveniles of Unio mancus indoor is an aquacultural system without water recirculation, where juvenile mussels showed the most favorable growth (1.432,17 +/- 136,6μm) and survival values (57,5 +/- 15,26%) at 60 days. It can be concluded that the most effective method for breeding juveniles is the one with the best algae formulation for the species studied and excellent qualities of water and culture environment