Analysis of feeding behavior and food consumption rate of Atlantorchestoidea brasiliensis (Crustacea: Talitridae)

Abstract

Talitrid amphipods are considered one of the most important wrack-deposit consumers in the intertidal zone of sandy beaches due to their ability to remove extensive amounts of macrophytes. The quantity and composition of drift macrophytes can influence the consumption and demographic rates of talitrid species. However, on coasts with a low contribution of macrophytes, where organic material is typically composed of debris, algal fragments, and vascular plants, the feeding behavior of talitrids is poorly understood. Along the south coast of Brazil, the amphipod Atlantorchestoidea brasiliensis is the most abundant species of macrofauna on exposed sandy beaches that do not have a high abundance of macroalgal wrack. In order to understand the feeding behavior of this species, experiments on food preference and consumption rates were carried out, and the ability to feed on the surface or buried within the substrate was also tested. Food items offered included the sand crab Emerita brasiliensis, the wedge clam Donax hanleyanus, the mullet fish Mugil sp., and the alga Ulva sp., species that commonly comprise debris on the drift line. Adult amphipods showed a broad feeding range. The most commonly consumed food items were E. brasiliensis and D. hanleyanus, which were consumed more during the night, while Mugil sp. was the least consumed item during both the day and night. In the food preference trials, algal consumption was negligible, suggesting that feeding on debris is more important for this species. Amphipods preferred fresh algae rather than dried algae when simultaneously offered both food items. Our results indicate that talitrids have different feeding strategies and behavior according to the type of organic material deposited on the beach.