Does regeneration affect feeding efficiency in the fissiparous starfish Allostichaster capensis in Golfo Nuevo, Argentina?

VILLARES, GABRIELA; RUBILAR, TAMARA; PASTOR DE WARD, CATALINA TERESA

Bahia Blanca, Argentina

Simposio; Estuarine and Coastal Sciences Association (ECSA) 44 Symposium; 2008

Instituto Argentino de Oceanografía – Universidad del Sur

Allostichaster capensis is a fissiparous starfish that inhabits the South Atlantic Ocean. In Golfo Nuevo displays annual cycles in both sexual and asexual reproduction. The population undergoes fission during the summer, after spawning, and regeneration occurs during the rest of the year. Thus, nutrients must be shared between both reproductive strategies as they are energy demanding. Due to arm loss during fission could cause negative effects in the individuals, such us reduce predatory efficiency, reproduction and locomotion. The aim of the study was to investigate the effect of regeneration in the feeding efficiency of the starfish. Three experiments were conduct with individuals with different degree of regeneration: recently split, regenerating and intact individuals. During each experiment animals were divided in three groups with different availability of food: low, intermediate and high. Results showed that arm loss, due to fission; reduce feeding efficiency, since the ability of tackling preys appears to be weakened. This generates low tissue consumption, diminishing the input of energy. Arm growth could regain the ability to obtain food, improving the efficiency of feeding. This intake of nutrients could facilitate regeneration and production of gametes. Availability of food and nutritional state of the individuals appear to be the most crucial factors for the individuals to be able to reproduce by both strategies.