Annual recruitment, predation rates and biocontrol of Linatella caudata (Mollusca: Gastropoda) in suspended enclosure culture of the pearl oyster Pinctada imbricata

Abstract

We present data on recruitment of the marine gastropod Linatella caudata (Gmeling, 1791) and their predation rates on the pearl oyster Pinctada imbricata in suspended culture using Spanish baskets. The recruitment rate of juveniles of L. caudata was studied every 30days over a year. The bivalve culture enclosures were suspended in the water column at two sites in the Gulf of Cariaco (northeastern Venezuela) characterized by different oceanographic and environmental conditions; Turpialito and an internal area of Laguna Grande del Obispo (LGO). Environmental variables including temperature, chlorophyll a, total (organic and inorganic) seston and wind intensity were recorded. The sea urchin Echinometra lucunter was placed on culture baskets as a predator (biocontrol). Plastic mesh cultivation bags were also tested as an alternative method to prevent or decrease the recruitment of these predators at Turpialito. The results showed a significantly higher number of predators at Turpialito than in the sheltered LGO site in May, June and July only. During the period of intense predator recruitment, principal component analysis (PCA) revealed that chlorophyll a, organic seston and wind strength were directly related to predator recruitment. During the period of less intense predator recruitment when wind intensity was lower, PCA showed that the same variables were directly related to predator recruitment whereas temperature showed an inverse relationship. In contrast, no relationship between recruitment of predators and environmental variables could be established for the LGO site. However, predator recruitment at LGO was significantly lower in the plastic mesh bags than in Spanish baskets, and in the presence of the sea urchin Echinometra lucunter. Due to high rates of predation observed, L. caudata constitutes a serious problem for the aquaculture industry of marine bivalves.