Spatio-temporal distribution of Olivella minuta (link, 1807)(Mollusca, Gastropoda,...
| Grant number: | 09/17585-6 |
| Support type: | Regular Research Grants |
| Duration: | April 01, 2010 - September 30, 2012 |
| Field of knowledge: | Physical Sciences and Mathematics - Oceanography |
| Principal Investigator: | Alexander Turra |
| Grantee: | Alexander Turra |
| Home Institution: | Instituto Oceanográfico (IO). Universidade de São Paulo (USP). São Paulo , SP, Brazil |
Abstract
Olivella minuta is an olividae gastropod common and abundant on beaches on the northern coast of São Paulo state. However, information on this species, as well as on other gastropods on sandy beaches on the Brazilian coast, is scarce and restricted, in general, to aspects of spatial distribution, occurrence in communities, morphology, and systematic. Ecological studies may subsidize the comprehension of possible inter population differences in terms of abundance, diet, size structure, growth, mortality, and reproduction caused by different physical features of the beaches. Simultaneously, the monitoring of these ecological aspects might clarify how the populations are affected by anthropic action, which is intense and varied in this environment, in addition to providing subsidies for the elaboration of management and preservation plans. In this scenario, this project aims at carrying out a wide study on the ecology of O. minuta on two protected beaches in São Sebastião channel (Araçá e Barequeçaba), with different environmental features and macrofauna composition. The space distribution of O. minuta will be analyzed on the two beaches considering both environmental and biotic factors. The analysis and comparison of diet, allometry, and reproductive aspects of the two species of O. minuta will be performed. Parameters of population dynamics, such as growth, mortality, and life span will be estimated, analyzed, and compared between populations. The use of growth rings of the statolith of O. minuta as structures indicating individual age and growth will be evaluated for the first time for a gastropod of a tropical region. This project also aims at verifying if O. minuta females present imposex. Due to the presence of the Port of São Sebastião and an Oil Terminal in the region, the two populations of O. minuta are exposed to a potential risk of developing imposex. Finally, the secondary production and turnover rate of populations of O. minuta will be estimated providing a quantitative basis to understand the importance of O. minuta in the energy flow on Araçá and Barequeçaba beaches. For these purposes, monthly samplings will be carried out on both beaches through one year, based on five transects. From each transect, 12 samples will be obtained with a 0.50 m-side square, summing up 60 samples/beach/month. In the laboratory, the shells of O. minuta individuals will be measured in several morphometric parameters for the study of the allometry and the growth. Subsequently, the shells will be broken for the analysis of stomach content, gametogenic cycle and inspection of imposex on females. It is expected to conduct a detailed and diversified analysis on populations of sandy beaches, which is rarely found in the literatura. (AU)