Does the gathering of shellfish affect the behavior of gastropod scavengers on sandy beaches? A field experiment

作者：Garcia Garcia Francisco J^*; Jose Reyes Martinez M; Carmen Ruiz Delgado M; Sanchez Moyano Juan E; Castro Casas Macarena; Perez Hurtado Alejandro

来源：Journal of Experimental Marine Biology and Ecology, 2015, 467: 1-6.

DOI：10.1016/j.jembe.2015.02.016

• Behavior
• Cyclope neritea
• Human trampling
• Sandy beach
• Scavenger

Carrion on beaches is an unpredictable and ephemeral resource over time, especially in areas affected by a tidal regime whereby the ground is frequently washed by incoming tides. In this ecosystem, economic activity, such as the commercial harvesting of molluscs, leads to the presence of discarded, damaged and dying specimens of bivalves on the sand. Thus, although carrion usually represents a minor food source on sandy beaches, human harvesting activity can lead to a significant contribution, this being majorly important for scavengers. During low tide, intertidal gastropod scavengers remain buried in the substrate and emerge when they detect carrion. However, in some instances these gastropods may also emerge in response to mechanical disturbance regardless of the presence of food. The study reported here aims at investigating the effect of human activity, such as trampling on sandy beaches during shellfish gathering, on the behavior of the gastropod scavenger Cyclope neritea in terms of emersion and food locating. This goal was achieved by carrying out short-term field experiments on a sandy beach on the European Atlantic coast (SW Spain). The results demonstrate that, as with the presence of carrion on the ground, human trampling affects the behavior of C. neritea, favoring its emersion to the sediment surface and its movement on the ground. It is hypothesized that this is a potential trophic facilitation by shellfishers, since the emersion and movement of gastropods at low tide is induced during the period when the amount of food on the ground increases due to shellfish gathering. Nevertheless, this increased activity also implies a higher predation risk for these scavengers while emerging from the sand. In order to avoid predation, gastropods generally use alarm cues, such as the detection of damaged conspecifics, as an anti-predatory strategy. The behavioral response of C neritea to the presence of damaged conspecifics was also studied. The results of this study highlight the fact that scavengers emerge from the sediment in response to trampling and the presence of carrion on the sediment surface. Further it is shown that although the presence of damaged conspecifics may act as a cue to gastropods, C neritea does not respond to this stimulus until it first makes contact.

• 出版日期2015-6