Recruitment of oyster in artificial collectors on the Amazon macrotidal mangrove coast

Abstract

The purpose of this study was to determine the moment of the year for the oyster recruitment and define the type of collector and environmental conditions that maximize recruitment. Collections were conducted, during 12 months, on Amazon Macrotidal Mangrove at two different sites: raft (point I) and mangrove (point II). In each location three types of collectors were used (1) transparent PET bottles, (2) green PET bottles, and (3) PVC sheets, each with three replicates. Spats were counted and measured at 45-day intervals, while the environmental data were measured every two weeks. Identification of oyster species occurred by genetic testing (multiplex PCR) by randomly selecting individuals by sampling. Results indicated spat capturing was significantly influenced by the collector type, location and period of collection (P<0.05, MANOVA) with significantly higher recruitment in the PVC collector (P<0.05, Tukey test). Oyster recruitment occurred throughout the year, suggesting that these individuals reproduce during all months; however, months with less rain and greater salinity were the best for spat collection, while the rainy period with lower salinity proved to be the best for individuals growth. The location in interaction with the environmental variables, mainly salinity, has a significant effect on the recruitment rate of spat and on their size, so that point II (mangrove) had the best results for recruitment and point I (raft) provided the spats of the largest size. Genetic identification verified two native oysters species (Crassostrea gasar and Crassostrea rhizophorae) in both points (I and II).

Variation in environmental characteristics of waters among Amazon coast oyster culture units

“…Survival and growth of C. gasar seed in the laboratory were highest in intermediate salinities (20 -25), but remained very high between 10 and 45 (Funo et al 2015) or tolerated 21 -35 with optimal results at 28 (Legat et al 2017a). In the field, settlement of mangrove oysters is greater in the dry period, when salinity is high, but growth is higher at low salinity (Funo et al 2019). In Brazilian mangroves, the abundance of seed of C. rhizophorae and C. gasar declines at salinities below 19 and 25, respectively (Nascimento 1991).…”

“…Although selected physical-chemical variables have been examined in relation to oyster reproduction, survival and growth at some units in Pará (Paixão et al 2013;Funo et al 2015;Oliveira et al 2018), as well as trace elements at all units in the peak wet and dry months (Silva et al, 2018), no standardized study of a more diverse range of variables has been undertaken at all units. The dynamics of life history parameters of C. gasar are highly seasonal and associated with temperature, salinity, pH, dissolved oxygen, degree of submersion and microalgal concentrations for larval settlement, juvenile and adult survival and/or growth (Nascimento 1991;Lemos et al 1994;Ramos and Castro 2004;Alvarenga and Nalesso 2006;Lopes et al 2013;Funo et al 2015;Funo et al 2019;Legat et al 2017a,b;Oliveira et al 2018) and reproduction (Christo and Absher 2006;Paixão et al 2013;Ramos et al 2013;Gomes et al 2014).…”

Effect of stocking density on the growth and survival of Anomalocardia brasiliana (Gmelin, 1791) (Bivalvia: Veneridae) post-larvae

“…It belongs to the Veneridae family and found in place of lives at water depths ranging from 0.5 to 1.5 m into shallow sandy grounds near mangroves. It is sensitive to environmental variations; high mortality levels are noted during the rainy season which causes large fluctuations in the size and distribution of populations (MONTI et al, 1991;MOUËZA et al, 1999;FUNO et al, 2019).…”

A Pesca Artesanal Em Áreas De Inundação No Baixo Amazonas, Pará: Técnicas De Captura E Composição Pesqueira

“…Funo et al (2019) observou que o período mais propício de coleta de sementes desta espécie no litoral maranhense foram os meses de estiagem, entre os meses de junho e dezembro. Os meses do período chuvoso recrutaram sementes de maior tamanho e foi constatado menor interferência de outros organismos incrustantes, no entanto as sementes de ostra tiveram menos indivíduos assentados nos coletores.…”