• Corpus ID: 209685889

Recruitment of oysters of Crassostrea genus (Bivalvia, Ostreidae) in Guaratuba Bay, PR, Brazil

@inproceedings{Usete2017RecruitmentOO,
  title={Recruitment of oysters of Crassostrea genus (Bivalvia, Ostreidae) in Guaratuba Bay, PR, Brazil},
  author={Usete and C. W. and Hristo and ndrea and C. C. and Ruz and K – and Aled and Heresinha and A. M. and Bsher},
  year={2017}
}

• Usete, C. W., +8 authors Bsher
• Published 2017
• Environmental Science

Larval development of Crassostrea is characterized by three larval phases: larva D, Umbo and Pediveliger. In Pediveliger the larvae are near settlement and metamorphosis in hard substratum. In this work, recruitment of oysters’ larvae of genus Crassostrea (C. rhizophorae and C. brasiliana) was studied in Guaratuba Bay (Paraná – Brazil) through analysis of artificial collectors placed in three points: Point I (bay ́s entrance), Point II (cultivation park) and Point III (medium sector of the bay) and changed biweekly from June/2003 to June/2004. Due to the impossibility to differentiate the recruits of the two oysters’ species by the shell morphology, the oyster’s spats of the two species were counted jointly on both sides of the plates, to determine the number of settled individuals. The results showed an increase in the number of settled individuals between October and March with successive peaks during this period. The medium sector of the bay showed the larger density of recruits along the studied period. An important application of the present research would be in the improvement of oyster cultivation based in seed collection from natural environment. Key-words: larvae, collectors, spats, Guaratuba Bay, South Atlantic. Resumo. Recrutamento de ostras do gênero Crassostrea (Bivalvia, Ostreidae) na baía de Guaratuba, PR, Brasil. O desenvolvimento das larvas de ostras do gênero Crassostrea é caracterizado em fases larvais: larva D, umbo e Pediveliger. No estágio Pediveliger as larvas estão próxima da metamorfose e assentamento no substrato consolidado. Neste trabalho o recrutamento das larvas de ostras do gênero Crassostrea (C. rhizophorae e C. brasiliana) foram estudados na baía de Guaratuba (Paraná, Brasil) através da análise de coletores artificiais em três locais: ponto I (entrada da baía), ponto II (parque de cultivo) e ponto III (setor médio da baía) e a variação quinzenal entre junho/2003 a junho/2004. Devido à impossibilidade de diferir os recrutas das duas espécies nativas de ostras a partir da morfologia da concha, as sementes das duas espécies foram contadas em conjunto de ambos os lados das placas, para determinar o número de indivíduos fixados. Os resultados mostraram um aumento no número de indivíduos fixados entre os meses de outubro e março, com sucessivos picos durante este período. O setor médio da baía mostrou a maior densidade de recrutas ao longo do período estudado. Uma aplicação importante da presente pesquisa seria no aperfeiçoamento do cultivo de ostras com base na coleta de sementes do ambiente natural. Palavras chaves: larvas, coletores, sementes, baía de Guaratuba, Atlântico Sul. Introduction During early developmental stages (D-larvae and Umbo-larvae), Crassostrea spp. larvae are abundant in surface plankton, sinking to deeper Pan-American Journal of Aquatic Sciences (2016), 11(4): 301-308 302 S. W. CHRISTO ET AL. waters during late (pediveliger) stages (Andrews 1983, Boehs & Absher 1997, Baker 2003, Finelli & Wethey 2003). At settlement, substrate selection is a key factor controlling species distribution at local scales (Southworth & Mann 2004, Christo & Cruz 2009). The recruitment process in space and time scales can also supply information about the behavior of the adult oyster in the environment through the observation of the patterns of reproduction, spawns, estimates of the larval period, dispersion and growth associated to environmental factors (Southworth & Mann 2004, Wilson et al. 2005). Among these factors temperature, salinity, primary productivity and local hydrodynamic are very important (Boehs & Absher, 1997, Nalesso et al. 2008, Kim et al.2010, Haase et al. 2012). Researches with artificial substrate are quite spread in oyster culture, and have been used especially in areas where the artificial production of larvae in laboratory is unviable due to the high cost or when the objective is to increase settlement rate in the environment. In the recruitment process the interaction among genetic and environmental factors can also contribute to the substratum selection and settlement rate (Baker 2003, Finelli & Wethey 2003, Silveira et al. 2011). In the present study, the selection of the polypropylene substratum was based on previous works accomplished in Paranaguá Bay, on the influence of the substratum in the settlement of oysters’ larvae (Absher & Christo 1991, Christo & Absher 1993). The selection of the type of artificial substratum for the collectors is important in the optimization of spat recruitment in the nature (Sorabella & Luckenbach 2003, Jordan & Coakley 2004, Padilla & Klinger 2005, Su et al. 2007). The emphasis of the studies has been in the selection of the size of the collectors and materials of low cost and handling with the optimization purpose in the recruitment of larvae in nature (Mann 2001, Sorabella & Luckenbach 2003, Jordan & Coakley 2004, Padilla & Klinger 2005, Christo & Cruz 2009, Zanette et al. 2009). Therefore, this work had as objective to verify the space and time variation of larval recruitment of Crassostrea oysters (C. rhizophorae and C. brasiliana/C. gasar) through artificial collectors and identify their relationship to the environmental variables that act on the process of settlement of the seeds in the natural environment. Materials and Methods Guaratuba Bay situated on the coastal plain of southern Brazil (Fig. 1), has an area of 50.19 km and four cross-estuary sections (bay mouth; middle; São João river mouth; Cubatão river mouth) were established (Marone et al. 2006). The climate of the region is humid mesothermal. Marone et al. (2006) describes very dynamic situation, with strong currents (more than 2.0 m.s at the mouth), semidiurnal tides of up to 1.5 m range (0.65 m at neap tide), moving up to 75x10m of water at spring tide and 32x10km at neap tides in a complex tide propagation pattern (progressive, mixed and stationary). Oyster’s recruitment was analyzed, in the period from June 2003 to June of 2004, through artificial collectors placed at three locals of Guaratuba Bay, as follows: Point I (25°51’20’’S; 48°34’39’’W – bay mouth) close to Sepultura’s Island, in the entrance of the bay, where natural banks of oysters occur in rocky coasts. Point II (2549’56”S; 48 34’48”W middle) is located in a cultivation park of C. brasiliana in Pinheros’ River, formed by a tide channel in the northeast portion of the bay between Veiga Island and the continent. This channel has an approximate width of 150m, length of 2000m. Point III (25°52’12’’S; 48°38’21’’W middle) near Garças’ Island, in the medium sector of the bay has a mean depth of (Fig. 1). In each point 2 collectors with 5 plates of polypropylene each were placed, to 1 m depth from the sea surface. This depth was selected in order to prevent the establishment of native oyster according with preference of larvae settlement. C. rhizophorae is predominant intertidal and C. brasiliana/C. gasar is predominant infralittoral. A total of 10 plates were disposed in strings of galvanized wire and each plate with an area of 10 cm2 was placed 4 cm apart. Every 15 days the collectors were substituted and taken to the laboratory. Jointly to spat sampling environmental factors were measured: temperature with a mercury thermometer precision of 0.1 °C; salinity with manual refractometer precision of 1 unit; seawater transparency with Secchi disk. Pluviosity data was obtained from the meteorological station of Guaratuba of the Technological Institute SIMEPAR (Meteorological System of Paraná). Due to the impossibility to differentiate the recruits of the two oysters’ species by the shell morphology, the oyster’s spats of the two species were counted jointly on both sides of the plates, to determine the number of settled individuals. The number of spats settled in each plate was transformed in densities, expressed in individuals/100 cm2. Pan-American Journal of Aquatic Sciences (2016), 11(4): 301-308 Recruitment of oysters of Crassostrea genus 303 Figure 1 Location of points in Guaratuba Bay, Paraná – Brazil. Points: I (near Sepultura Island), II (cultivation park) and III (medium sector of the bay). Sections: bay mouth; middle; São João river mouth; Cubatão river mouth (Marone et al. 2006). Spats data were transformed (square root). After evaluated the normality and homogeneity of the data, one-way ANOVA was used to test for significant differences (a=0.05) in larvae densities (dependent variable) between plates (1 to 5) and side of the plate area (upper and lower). A two-way ANOVA was used to test for significant differences (a=0.05) in larvae densities (dependent variable) between points and stations sampled (independent variable). The correlation between the biological parameters and the environmental parameters was put in evidence through a multivariate analysis of ordination as a PCA (Principal Component Analysis) (Legendre & Legendre 1983, Valentin 2000), with the seasonal averages of the variables.