Secondary production and turnover rate can subsidize the comprehension of important ecological issues such as energy transfer within communities, monitoring and rational management of marine resources. However, it is observed that only few studies have this focus in beaches on the Brazilian coast and throughout the world. Such scarcity is mainly due to the methodological difficulties inherent to these studies, although the lack of referential bibliography is also a relevant factor. The present project aims to analyze the population dynamics and estimate the secondary production of the gastropod Olivella minuta, one of the most abundant species in Araçá beach as well as in Barequeçaba beach, north coast of São Paulo state. It is also an objective to verify if females of these populations of Olivella minuta show imposex. This phenomenon is characterized by the presence of male sexual features (penis and/or vas deferens) on female neogastropods and is induced by means of the use of anti-incrusting substances applied on hulls of vessels, of which the active principle is constituted by organotin compounds such as tributyltin (TBT). Due to the presence of the port of São Sebastião and the Oil Terminal in the study area, the populations of O. minuta which inhabit Araçá and Barequeçaba beaches are subject to a potential hazard of exposure to TBT and, consequently, to developing imposex. For the purposes mentioned above, monthly samplings will be performed in both beaches through an annual cycle beginning on January, 2009. The growth parameters of von Bertalanffy and instantaneous mortality rate, of both populations of O. minuta will be obtained by using, respectively, non-linear adjustment of age-length relation and the length-converted capture curve. To estimate the secondary production, the size-frequency methods and weight specific growth rate will be employed. This project has also as objective to perform an analysis based on existing literature of several direct and indirect methods used to estimate production in such environments, besides elaborating regressions between the turnover rate and biological variables, for taxonomic groups which are specific to sandy beaches. Such procedures might clarify and facilitate the choice as well as the appropriate application of production methods, identify indirect production methods suitable for specific groups and stimulate the development of production studies in such an important environment. (AU)
News published in Agência FAPESP Newsletter about the scholarship:
CARDOSO, RICARDO SILVA;
Patterns of sandy-beach macrofauna production.
Journal of the Marine Biological Association of the United Kingdom,
Web of Science Citations: 11.