Variations in the reproductive investment of a venerid bivalve, Callista chione

Abstract

Understanding variations in the reproductive cycle of commercial and ecologically important bivalve species is essential to address fisheries management and climate oscillation issues. Spatial and temporal trends in the reproductive cycle of Callista chione were analysed using standard histological procedures and gonadosomatic index (GSI) for two consecutive years at two coastal sites in the Adriatic Sea. Reproductive output and fecundity were analysed quantitatively to gain better insight into the seasonal energy balance with respect to gametogenesis. A seawater temperature difference of ~4°C between the two sites likely influenced the onset and duration of spawning. At Cetina (milder temperatures), spawning was prolonged and occurred between spring and July, whereas at Pag there was only one main spawning peak in July. Both histology and GSI showed similar trends, indicating GSI to be a reliable method for analysing the main characteristics of the reproductive cycle. Conversely, the use of the body mass index (BMI) as an indicator of gonad development should be addressed carefully. Intraspecific variation in energy allocation between populations suggested life strategies modified to different habitat conditions. A higher reproductive investment and output in the Pag population directed gonadal resorption to ensure the generation of a new cycle, whereas the higher fecundity at the Cetina site indicated the production of gonads from newly available food. These results suggest successful physiological acclimatization to recent increasing temperatures.

Impacts of man-made structures on marine biodiversity and species status - native & non-native species

“…temperature, salinity) to the successful establishment (reviewed by Olenin et al 2017). The probability of the species' successful establishment in a new environment is influenced by the species' life-history traits and the environmental conditions of the receiving habitat (Glasby et al 2007;Petes et al 2008;Piola et al 2009;van de Koppel et al 2015;Fava et al 2016;Firth et al 2017;Purroy et al 2019). There is evidence of nonnative species being relatively competitive and adaptable to harsh and disturbed environments.…”

“…Most of the non-native species have r-selected life-history traits, where the species have high fecundity, small-sized, have early maturity, competitive, phenotypic plasticity and can live in a novel low-quality environments (Glasby et al 2007;Petes et al 2008;Piola et al 2009;Fava et al 2016;Purroy et al 2019). Few experimental studies comparing the native and non-natives and their response to pollution (e.g.…”

“…Another aspect to consider the successful invasion is the suitability of environmental conditions of the receiving habitat (Lockwood et al 2005; Petes et al 2008;Piola et al 2009;van de Koppel et al 2015;Fava et al 2016;Firth et al 2017;Purroy et al 2019). There is evidence of anti-equatorial and latitudinal shifts in species' distributions due to changing global climate (Herbert et al 2007;Keith et al 2011;Poloczanska et al 2016).…”

“…Not all non-native species can successfully establish due to unsuitable climatic conditions, diseases, predation and competition by native species through species-specific interactions or invasion resistance by the diverse native community Tilman et al 1994;Mack et al 2000;Stachowicz et al 2002;Dumont et al 2011;Henriksson et al 2016;Leclerc & Viard 2018). The successful non-native species may be highly competitive in terms of their high reproductive/growth rates and phenotypic plasticity, which aids their introduction and establishment success in a new environment (Petes et al 2008;Piola et al 2009;MacKie et al 2012;Fava et al 2016;Purroy et al 2019). Once established, the non-native species disperse further from the introductory areas (Tyrrell & Byers 2007;Forrest et al 2009).…”