The effects of season and wrack subsidy on the community functioning of exposed sandy beaches

作者：Goncalves Silvia C^*; Marques Joao C

来源：Estuarine, Coastal and Shelf Science, 2011, 95(1): 165-177.

DOI：10.1016/j.ecss.2011.08.036

• macrofaunal communities function
• seasonality
• wrack subsidy
• exposed sandy beaches
• secondary production

Seasonality is an important component of the climate, known to influence several biological events that can be reflected in community structure and organization. However, sandy beach macrofaunal community ecological studies are frequently based on snapshot sampling events, neglecting this important dimension and its effects. In the present study, the effects of seasons and wrack subsidies on macrofaunal communities function of two similar exposed sandy beaches of Portugal was monitored for approximately 18 months by sampling all the beach area, from the shoreline to the base of the dunes. The study assessed the beach physical environment, community density and composition, trophic structure, secondary production of key species and the potential relationships between biological data and environmental parameters. Seasonality, particularly temperature variations, and the interaction between seasons and the beach zones (supralittoral vs. intertidal areas) had a strong influence on the communities, promoting a differential utilization of the beach by several species. Seasons also shaped the density of trophic groups, with consequences in community composition and function. Differences between beaches were observed on wrack subsidy, community composition and relative contribution of the dominant species, but the trophic structure was stable and dominated by scavengers. Talitrus saltator was the most productive key species, and the contribution of the resident key species regarding secondary productions and standing stocks was different between beaches. Wrack quantity and deposition frequency on the beach had a positive influence on several faunal descriptors such as density and number of species of various functional groups. The present study also highlights the clear dependence of macrofauna of exposed sandy beaches on the wrack subsidies brought ashore by the tides, illustrating their role on community organization regarding several wrack-associated species and not only scavengers.

• 出版日期2011-11-1