Diet and feeding activity of Olivella minuta (Link, 1807) (Mollusca, Gastropoda, Olividae) along the intertidal - subtidal zone of a dissipative sandy beach in the north coast of São Paulo - Brazil

• Autor(a) principal: Silva, Mariana Oliveira
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.1/7441
• topic: Biologia marinha; Zonas costeiras; Comunidades; Populações; Alimentação; Gastrópodes

The present study aimed to investigate the diet and feeding activity of a sandy-mud snail, Olivella minuta along the gradient subtidal-intertidal of a dissipative morphodynamic beach: Barequeçaba (southeast coast of Brazil). Locomotor behavior of the species was also evaluated in laboratory conditions. The sampling was carried out in March, April and May, 2013 in the intertidal zone during low and high tide and in the subtidal zone during low tide, to further comparisons if these organisms change their diet according to the variation of the tide. Thirty specimens from 7 mm of length were caught in each situation and stomach contents were analyzed by means of qualitative (richness, diversity, evenness and Simpson) and quantitative indexes (numeric importance (NI) and frequency of occurrence (FO)). Also, the index of stomach repletion was calculated to complement the analysis of the feeding diet of this gastropod. A total of 49 items was registered in the digestive tracts of O. minuta being the most frequents: macroalgaes (48%), microalgaes (15%), artropodes (12%) and foraminiferans (12%). The remaining items had frequency of occurrence lower than 10%. The results of the diet composition of the individuals did not differ along the tidal range of the beach, suggesting that the species does not possess a preference for a single food resource, and the variation on NI e FO in all studied situations can be merely consequences of the dynamics of each food items during the tidal cycle. The results of the stomach repletion suggest that this snail feed in all studied situations, but with higher intensity when emerged during low tide and the results of locomotor behavior tested experimentally, reinforce this idea and still suggests that during the day this organisms have a higher feeding activity rather than at night, since a lesser movement was displayed in these conditions.