Latitudinal gradients in Scrobicularia plana reproduction patterns, population dynamics, growth, and secondary production

The bivalve Scrobicularia plana is a dominant species in terms of biomass and productivity in intertidal soft-substrate benthic communities along the NE Atlantic area. As such, it constitutes an important link in the food web and as a human food source, with high commercial and economic value. Several studies have suggested the existence of latitudinal variation in the ecological patterns of the species along its geographic distribution range. In the present study, a review and a comparison among previous studies on this species were performed. The resulting patterns of reproduction, population dynamics, growth and secondary production were analysed, and possible relationships between latitude and S. plana's ecological patterns and life strategies assessed. Results suggest the existence of different life strategies, depending on temperature, latitudinal gradient and local habitat conditions. Higher-latitude populations usually exhibit low abundance values, shorter reproduction periods and a 'slower' lifestyle, with lower growth rates (0.1 < k < 0.2, where k is a growth coefficient), extended lifespan and lower productivity. Areas between 40 and 45 degree N seem to present optimal ecological conditions, with the highest abundance values registered, longer reproduction periods, 'faster' growth (0.3 < k < 0.8) and higher productivity, while further south, populations showed lower abundance, productivity and growth rates.