Lagoons are highly productive areas representing more than 50% of the coastline area in Languedoc-Roussillon (South of France, Mediterranean sea). These lagoons are very different in their environmental conditions, human influences, eutrophication levels and aquaculture intensity. Based on macrophyte communities associated with soft substrates, two indices of taxonomic diversity (the "average taxonomic distinctness" (Δ+) and the "variation in taxonomic distinctness" (Λ+)) were used to discriminate four of these lagoons (Thau, Salse-Leucate, Bages-Sigean and Mauguio). Bages-Sigean presented a significant higher average taxonomic distinctness (p < 0.05) and Salse-Leucate had a significant higher variation in taxonomic distinctness (p < 0.05) without considering exotic species. The index values were neither influenced by sample size nor by presence of exotic species. Thus, the "average taxonomic distinctness" was related to human activities and eutrophication level whereas the "variation in taxonomic distinctness" was more related the environmental variability, associated with the prime stressor of salinity in brackish coastal lagoons.
Dinophysis sacculus and D. acuminata increased mortality of Crassostrea gigas oocytes Exposure of oocytes and spermatozoa to 0.5 cells mL -1 of D. sacculus decreased subsequent fertilization success Oyster gametes were negatively affected by exposure to whole culture or resuspended cells of Dinophysis spp. 5 nM of PTX2 decreased fertilization success of oocytes and 500 nM of PTX2 increased ROS production; OA showed no effect
The cryptophyte Teleaulax amphioxeia is a source of plastids for the ciliate Mesodinium rubrum and both organisms are members of the trophic chain of several species of Dinophysis. It is important to better understand the ecology of organisms at the first trophic levels before assessing the impact of principal factors of global change on Dinophysis spp. Therefore, combined effects of temperature, irradiance, and pH on growth rate, photosynthetic activity, and pigment content of a temperate strain of T. amphioxeia were studied using a full factorial design (central composite design 23*) in 17 individually controlled bioreactors. The derived model predicted an optimal growth rate of T. amphioxeia at a light intensity of 400 μmol photons · m−2 · s−1, more acidic pH (7.6) than the current average and a temperature of 17.6°C. An interaction between temperature and irradiance on growth was also found, while pH did not have any significant effect. Subsequently, to investigate potential impacts of prey quality and quantity on the physiology of the predator, M. rubrum was fed two separate prey: predator ratios with cultures of T. amphioxeia previously acclimated at two different light intensities (100 and 400 μmol photons · m−2 s−1). M. rubrum growth appeared to be significantly dependent on prey quantity while effect of prey quality was not observed. This multi‐parametric study indicated a high potential for a significant increase of T. amphioxeia in future climate conditions but to what extent this would lead to increased occurrences of Mesodinium spp. and Dinophysis spp. should be further investigated.
The three D. cf. sacculus strains tolerated hypo-and hyperosmotic conditions (25 and 42 vs. 35) Higher proline, glycine betaine and DMSP contents of D. cf. sacculus at the highest salinity Growth, biovolume, toxin contents and profiles were not affected by salinity stress Metabolomics showed intraspecific variability of D. cf. sacculus but no clear salinity effect
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