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Short-Term Biochemical Biomarkers of Stress in the Oyster Magallana angulata Exposed to Gymnodinium catenatum and Skeletonema marinoi
Publication . Cereja, Rui; Cruz, Joana P. C.; Heumüller, Joshua; Vicente, Bernardo; Amorim, Ana; Carvalho, Frederico; Cabral, Sara; Chainho, Paula; Brito, Ana C.; Ferreira, Inês J.; Diniz, Mário; DQ - Departamento de Química; UCIBIO - Applied Molecular Biosciences Unit; LAQV@REQUIMTE; MDPI - Multidisciplinary Digital Publishing Institute
Bivalves accumulate toxins produced by microalgae, thus becoming harmful for humans. However, little information is available about their toxicity to the bivalve itself. In the present work, the physiological stress and damage after the ingestion of toxic dinoflagellate species (Gymnodinium catenatum) and a diatom species (Skeletonema marinoi, which is non-toxic to humans but may be to grazers) in the oyster Magallana angulata are evaluated against a control treatment fed with the chlorophyte Tetraselmis sp. Oysters were exposed for two hours to a concentration of 4 × 104 cells/L of G. catenatum and 2 × 107 cells/L of S. marinoi. The biomarkers superoxide dismutase (SOD), catalase (CAT), glutathione S-Transferase, total Ubiquitin (Ubi) and Acetylcholinesterase (AchE) were assessed. The exposure of M. angulata to G. catenatum lead to a reduction in SOD and AchE activity and ubiquitin concentrations when compared to the control treatment. Moreover, it increased CAT activity in the adductor muscle, and maintained its activity in the other tissues tested. This may be related to the combination of reduced metabolism with the deployment of detoxification processes. S. marinoi also lead to a decrease in all biomarkers tested in the gills and digestive glands. Therefore, both species tested caused physiological alterations in M. angulata after two hours of exposure.
Seagrass space occupation efficiency is key for their role as ecosystem engineers and ecological indicators
Publication . Vieira, Vasco M.N.C.S.; Santos, Rafael; Leitão-Silva, David; Veronez, Arthur; Neves, Joana M.; Nogueira, Marta; Brito, Ana; Cereja, Rui; Creed, Joel C.; Bertelli, Chiara M.; Samper-Villarreal, Jimena; Bartilotti, Cátia; Lobo-Arteaga, Jorge; MARE - Centro de Ciências do Mar e do Ambiente; UCIBIO - Applied Molecular Biosciences Unit; Springer Nature
Studies for the preservation of seagrass beds biotopes have met difficulties in establishing appropriate methods assessing their health. We tested the efficiency of space occupation by seagrasses scattered worldwide (dgrass index), which proved to be dependent on clonal growth form and morphometric plasticity. dgrass correlated with the above-ground to below-ground biomass ratio. However, the latter was misleading when high ratios resulted from low below-ground biomass. Nutrient Posphate-limitations were revealed in situations of theoretical Nitrogen-limitation. Enhanced nutrient supply benefitted seagrasses only up to a threshold after which it became detrimental. Better nurtured, healthier meadows with denser canopies increased the organic matter in the sediment and had associated greater abundances of benthic macrofauna. Hence, seagrass biotopes could benefit from moderate anthropogenic nutrient additions. However, organic matter above ≈6% and/or reduced riverine discharges (dams upstream and climate-change-related droughts) were detrimental to healthy meadows, jeopardizing ecosystem services such as macrofauna abundances and carbon sinks.
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Fundação para a Ciência e a Tecnologia
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CEEC IND 2017
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CEECIND/00095/2017/CP1387/CT0038