Description: The present study examines the influence that environmental variables exerted on changes in condition index (CI), shell height (SH—dorsal-ventral axis) and soft tissue mass increments (STM) of the winged oyster Pteria colymbus in suspended culture during periods of upwelling (December to April) and non-upwelling (August to November) in the Cariaco Gulf, northeastern Venezuela. Environmental variables recorded between April 2012 and May 2013 included seston, water transparency, temperature, dissolved oxygen, chlorophyll a (Chl a) and the upwelling index (UI). Individuals were cultivated in lantern nets with an overall density of 56 individuals/0.123 m2. From three randomly chosen baskets, five individuals were sampled each month and changes in CI, STM and SH were related to the environmental variables using Spearman correlation and PCA. Results show that during upwelling, both Chl a and UI presented a positive and significant relationship with the oyster condition and growth parameters. During non-upwelling (low UI), this relationship was inverse, demonstrating the important influence of upwelling and non-upwelling periods on the ecophysiology of the species. Furthermore, it was shown that the non-upwelling, characterized by high temperatures and low food availability, is a critical period for P. colymbus, judging by a decrease in growth and survival rate. Nonetheless, this species reached 50 mm in 5 months, a size considered as commercially viable, suggesting that the study area is favourable to the cultivation of the winged oyster despite a dramatic decrease in upwelling intensity in the last decade.

Description: 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 30 days 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.