Population biology and secondary production of the harvested clam Tivela mactroides (Born, 1778) (Bivalvia, Veneridae) in Southeastern Brazil

Abstract

The population structure, growth and production of the trigonal clam Tivela mactroides were investigated by monthly sampling between January 2003 and October 2004 in two areas (southern and northern) of the intertidal and subtidal zones of Caraguatatuba Bay, Southeastern Brazil. Intertidal sampling was carried out in each area along eight transects perpendicular to the shoreline. In the subtidal zone of both areas, one 50-m dredging was performed along five sampling stations arranged on three transects perpendicular to the coast. The intertidal abundance of T. mactroides was higher in the southern (more dissipative conditions) than in the northern area. High abundances occurred in February-March 2004 in the south and in September 2004 in the north. The size structure showed that younger individuals dominated in the sublittoral, indicating that recruitment occurs in this zone, followed by the migration of these individuals to the intertidal, where they complete their life cycle. Tivela mactroides showed continuous reproduction, with 26 cohorts detected in the study period. The lower estimates for the growth index (/′ = 3.22), mortality rate (Z = 2.10 year À1 ) and turnover rate (P/B = 1.21 year À1 ), and conversely the longer life span (2.5 years) of T. mactroides in Caraguatatuba Bay (24°S) compared with Venezuelan populations (10°N) suggests a latitudinal pattern of these life-history traits. The high production of T. mactroides in Caraguatatuba Bay was due to continuous recruitment and rapid and continuous growth, and demonstrates the importance of T. mactroides as a biological resource for many marine species and for the local residents.

Reproductive cycle of the trigonal clamTivela mactroides(Bivalvia, Veneridae) in Caraguatatuba Bay, southeastern Brazil

“…The data presented here indicate that a management strategy based on the reproductive pattern of this population of T. mactroides would not be viable, since it is difficult to identify a specific period when spawning is more intense. Although we recorded periods of greater maturation during winter and spring, a study of the population dynamics of the species (Turra et al 2014b) showed that this venerid recruits almost continuously through the year. However, this situation may result from other factors such as reduced predation pressure or even better environmental conditions (e.g.…”

“…Considering the maturation pattern of the females, the increase in the gametogenesis in T. mactroides during winter and spring suggests a slight summer-autumn spawning intensification. However, given the existence of constant recruitment events during the year in Caraguatatuba Bay (Turra et al 2014b), spawning may also occur in other periods, although with less intensity.…”

“…Turra et al (2014b) observed several recruitment pulses in this same period, and estimated a total of 10 recruitment cohorts within a one-year interval. Considering the maturation pattern of the females, the increase in the gametogenesis in T. mactroides during winter and spring suggests a slight summer-autumn spawning intensification.…”

Reproductive cycle and parasitism in the clamAnomalocardia brasiliana(Bivalvia: Veneridae)

“…Latitudinal differences in life history traits have been described for several bivalves, such as Donax hanleyanus (Cardoso & Veloso 2003;Herrmann et al 2009) and Tivella mactroides (Turra et al 2014), and are likely to affect the reproduction of A. brasiliana as well (Grotta & Lunetta 1982). All studies that analyzed the reproductive biology of A. brasiliana in tropical regions (sensu Spalding et al 2007) have reported no resting period (Table 1), whereas a resting stage was detected at Araçá (this study) and in the state of Santa Catarina (Araújo 2001), which is the southernmost location where the reproduction of A. brasiliana has been investigated.…”

A Pesca De Moluscos Em Ambientes Intermareais No Oeste Do Estado Do Rio Grande Do Norte, Brasil

“…Estes moluscos são comumente capturados pela população local para o consumo próprio, sendo a sua captura predominantemente realizada por mulheres. Esses bivalves formam densas populações, o que os torna susceptível a pesca (Ocaña, 2015;SilvaCavalcanti & Costa, 2011;Turra et al, 2014).…”