Seasonal variations of amphipod assemblages in a Posidonia oceanica (Linnaeus) Delile, 1813 meadow from the central Tyrrhenian Sea (Italy)

Abstract

Temporal variability in species composition and abundance may enhance coexistence in ecological communities, especially when subjected to strong seasonal patterns. Species distribution through time may be related to many factors, such as changes in the structure and functioning of preferred habitats, variations in ecological interactions or asynchronous patterns in species life cycles. Here, data from a one-year survey of amphipod assemblages from a nearly undisturbed Posidonia oceanica meadow are used to investigate the seasonal patterns in species abundance and identity. Our results highlight the presence of a core group of species inhabiting the meadow throughout the year, although an in depth analysis reveals three differentiated seasonal assemblages corresponding to autumn, winter, and a warm season clustering of both spring and summer. The observed patterns suggest the interplay between different mechanisms drives the coexistence of amphipods over the whole year, including niche partitioning, predation pressure, and variations in life history traits.