Diel and seasonal influences on the surfzone ichthyofauna of a tropical island in Ubatuba, SP

• Grant number: 15/07829-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2015
• End date: June 30, 2016
• Field of knowledge: Biological Sciences - Zoology
• Principal Investigator: George Mendes Taliaferro Mattox
• Grantee: Pedro Dias Barreto Neto
• Host Institution: Centro de Ciências Humanas e Biológicas (CCHB). Universidade Federal de São Carlos (UFSCAR). Sorocaba , SP, Brazil

Abstract

The surf-zone of sandy beaches acts as nurseries, housing a great number of larval and juvenile fish. Among the available factors in this environment is the possibility of shelter against predators and a rich source of zooplanctonic food. The surf-zone ichthyofauna is often characterized by its low richness and high dominance by one or few species when compared to deeper regions of the ocean, in addition to presenting a low number of resident species. Abundance and composition of the fish community of the surf-zone are subject to abiotic factors (e.g., tidal, wind direction and speed, salinity, etc) as well as seasonal and diel variations. Although the great importance of the surf-zone of sandy beaches for the life cycle of fishes, studies focusing on this environment in Brazilian islands are still scarce. Thus, this project initiated on November 2014 aiming at an ecological study of the ichthyofauna of the surf-zone of Prumirim Island, Ubatuba, SP, analyzing the composition and structure of the fish assemblage during full moon tides, taking into account both seasonal and diel variations. Samplings have been occurring monthly with a beach seine, in the morning and at night at two sites along the beach. Data of salinity, air and water temperature are also collected. Six of the twelve planned sampling trips had already been carried on, totaling so far 31 species and 1512 individuals. By the end of the collecting trips, the effect of year seasons and periods of the day on indices such as diversity of Shannon-Wiener, Margalef and equability will be established by a Two Factor ANOVA. In addition, we will evaluate if abundance and biomass are different between seasons of the year through an ANOSIM, and an ordination diagram will be elaborated with a NMDS analysis to establish how similar the year seasons are according to the variables cited above.