Age and growth in three populations of Dosinia exoleta (Bivalvia: Veneridae) from the Portuguese coast

Abstract

The present study aimed at estimating the age and growth in three populations of Dosinia exoleta from the Portuguese coast (Aveiro in the north, Setúbal in the southwest and Faro in the south). Two techniques were compared to ascertain the most suitable method for ageing D. exoleta. Growth marks on the shell surface and acetate peel replicas of sectioned shells were the techniques applied. Two hypotheses were tested: growth parameters present latitudinal variation along the Portuguese coast; growth parameters are influenced by the fishing exploitation. Shell surface rings proved inappropriate for ageing this species, whereas acetate peels provided realistic estimates of the von Bertalanffy growth parameters (K, L ? and t 0 ). A latitudinal gradient in growth rate was detected, with a clear southward increase in the growth coefficient (K) of D. exoleta (Faro [ Setúbal and Aveiro) indicating that warmer waters in southern Portugal provide optimal conditions for the growth of this species. Fishing exploitation in northern Portugal targets larger individuals and leaves behind a younger population of smaller individuals, decreasing the asymptotic shell length (L ? ) of D. exoleta from Aveiro. The overall growth performance was compared among populations of D. exoleta and with other venerid species worldwide.

Growth variability in a metapopulation: The case of the southern geoduck (Panopea abbreviata)

“…Several studies have found latitudinal gradients in the rate of growth, such as those related to temperature (Beukema and Meehan, 1985;Cardoso et al, 2006;Gutiérrez and Defeo, 2003;Moura et al, 2013). In our work, we have found differences among all locations without latitudinal gradient, suggesting that growth is mainly governed by local environmental conditions, as occurs in other infaunal bivalve species (Gaspar et al, 2004;Gribben and Creese, 2005).…”

Responses of the mussel Brachidontes rodriguezii to aerial exposure: implications on growth and physiological condition

“…In addition, filter feeders biomass at rocky intertidal areas increases when food availability rises (Bustamante and Branch 1996). Growth rates of bivalve molluscs have been well studied through various methods, such as length frequency distribution (Maroñas et al 2003;Herrmann et al 2009), shell growth ring quantification (Kautsky 1982;Richardson et al 1990;Brey and Mackensen 1997;Richardson et al 1999;Soldati et al 2008;Bagur et al 2013;Moura et al 2013), and the analysis of size increments following mark-recapture experiments using tags, painting labels, and fluorescent stains (Day et al 1995;Linard et al 2011). Several chemical markers like strontium, calcein, and alizarin red were used for shell increment determinations through marking experiments (Fujikura et al 2003;Riascos et al 2007;Herrmann et al 2009).…”

Fishing and bottom water temperature as drivers of change in maximum shell length in Atlantic surfclams (Spisula solidissima)

“…Dredge fisheries have been shown to cause a decrease in maximum shell sizes in other clam populations. Both Moura et al (2013) and Dalgiç et al (2010) documented differences in growth and body size between fished and non-fished clam populations; however, the differences documented in Moura et al (2013) were confounded with a latitudinal gradient in growth conditions such that the unfished population came from warmer locations that were more conducive to faster growth and larger asymptotic size in the species (Dosinia exoleta) they were studying. This demonstrates the difficulty in distinguishing the relative influence of environment versus fishing in the absence of manipulation or controlled experiments.…”