Contrasting displacement of the sea cucumber Holothuria arguinensis between adjacent nearshore habitats

Abstract

Many sea cucumber species are subjected to exponentially increasing fisheries worldwide; management of their populations should take into account their behavior. Yet, studies relating feeding rates and displacement of sea cucumbers are, to date, scarce. The abundance, particulate organic matter (POM) consumption and displacement of the sea cucumber Holothuria arguinensis were compared between two adjacent, vegetated, habitats: a macroalgal dominated bed and a seagrass meadow formed by Cymodocea nodosa, at the island of Gran Canaria (eastern Atlantic). Abundances of H. arguinensis did not differ between the macroalgal bed and the seagrass meadow. No differences were found neither in POM consumption nor POM content between habitats. Movement of H. arguinensis occurred continuously during the day and nighttime, i.e. without resting periods. No sheltering behavior was observed. Faster and longer displacements were detected on the seagrass meadow than in the macroalgal bed, probably as a result of the different topography between habitats, independently of the daily period (day vs. night) and the moon phase. As a result, differences in locomotion of H. arguinensis between the two habitats are not connected with differences in POM consumption rates between habitats. These results could be useful for managing current and future fisheries of this species in the Mediterranean Sea and the Atlantic Ocean.