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Albert Calbet Mireia Bertos Claudio Fuentes-Grünewald Elisabet Alacid Rosa Figueroa Berta Renom Esther Garcés 《Harmful algae》2011,10(6):654-667
We isolated eleven strains of the harmful algal bloom (HAB)-forming dinoflagellate Karlodinium veneficum during a bloom event in the NW Mediterranean coastal waters and we studied the inter-strain variability in several of their physiological and biochemical traits. These included autotrophic growth parameters, feeding capabilities (mixotrophy), lipid composition, and, in some cases, their responses to biotic and abiotic factors. The strains were found to differ in their growth rates (0.27–0.53 d−1) and in the maximum cell concentrations achieved during stationary phase (6.1 × 104–8.6 × 104 cells mL−1). Their ingestion performance, when offered Rhodomonas salina as prey, was also diverse (0.22–1.3 cells per K. veneficum per day; 8–52% of their daily ration). At least two strains survived for several months under strict heterotrophic conditions (no light, low inorganic nutrients availability, and R. salina as food source). These strains also showed very distinct fatty acid compositions, with very low contents of monounsaturated and polyunsaturated fatty acids. According to a Bray Curtis similarity analysis, three or four strain groups able to perform different roles in bloom development were identified. We further analyzed one strain from each of the two most distinct groups with respect to prey concentration, light intensity, nutrient availability, and we determined the functional responses (growth and feeding rates) to food concentration. Taken together, the results served to highlight the role of mixotrophy and clone variability in the formation of HABs. 相似文献
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A total number of 40 potentially toxic microalgae and 5 taxa causing discolorations have been identified along the coasts of the Campania region (South Tyrrhenian Sea, Mediterranean Sea). This number is based on results of over 20 years of research at a coastal station in the Gulf of Naples, 4 years of monitoring activity along the Campania coasts and of a series of scattered and sporadic observations. Several species of the recently erected genera Karenia and Takayama are reported for the first time in the area. Information on the period of highest abundances or most probable period of occurrence indicates the late spring and summer as the periods of maximum risk of harmful events. Despite the variety of potentially toxic species, no human health problems nor fish kills have ever been recorded in Campania. The reasons for this apparent paradox are probably to be found in the ecological factors that regulate the abundance, toxicity and spatial distribution of the potentially harmful species and reflect as well the relatively low number of aquaculture plants in the area. 相似文献
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The association of algicidal bacteria and raphidophyte blooms in South Carolina brackish detention ponds 总被引:2,自引:0,他引:2
Over the past 5 years, raphidophyte blooms have been frequently observed along the South Carolina coastal zone. During the 2002, 2003, and 2004 sampling seasons, we investigated temporal fluctuations of algicidal bacteria abundance against raphidophycean flagellates (Heterosigma akashiwo, Chattonella subsalsa, and Fibrocapsa japonica) using the microplate most probable number (MPN) method in three Kiawah Island brackish stormwater detention ponds (K1, K2, and K75). Local axenic isolates of H. akashiwo, C. subsalsa, and F. japonica were obtained and their susceptibility to algicidal bacteria tested. A total of 195 algicidal bacterial strains were isolated from raphidophyte blooms in the study ponds, and 6 of them were identified at the genus level, and the taxonomic specificity of their algicidal activity was tested against local (pond) and nonlocal isolates of raphidophytes (3 species, 10 total strains). In the ponds, a consistent association was found between raphidophyte bloom development and an increase in bacteria algicidal to the bloom species. In 12 of 15 cases, bloom decline followed the increase in algicidal bacteria to maximum abundances. Although variability was found in the taxonomic specificity of the algicidal bacteria effect (i.e. the number of raphidophyte species affected by a particular bacteria strain) and raphidophyte susceptibility (i.e. the number bacteria strains affecting a particular raphidophyte species), a toxic effect was always found when strains of a raphidophyte species were exposed to algicidal bacteria isolated from a bloom caused by that same species. The results suggest that algicidal bacteria may be an important limiting factor in raphidophyte bloom sustenance and can promote bloom decline in brackish lagoonal eutrophic estuaries. 相似文献
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The value of harmful algal bloom predictions to the nearshore commercial shellfish fishery in the Gulf of Maine 总被引:1,自引:0,他引:1
In this study, we develop a framework for measuring the value of harmful algal bloom (HAB) predictions. The framework captures the effects of both private and public responses to HABs. Using data from the New England nearshore commercial shellfish fishery and impact estimates for a large-scale HAB event in 2005, we illustrate how the potential value of HAB forecasts may be estimated. The results of our study suggest that the long-term value of a HAB prediction and tracking system for the Gulf of Maine is sensitive to the frequency of HAB events, the accuracy of predictions, the choice of HAB impact measures, and the effectiveness of public and private responses. 相似文献
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Fernando P. Siringan Rhodora V. Azanza Neil John H. Macalalad Peter B. Zamora Ma. Yvainne Y. Sta. Maria 《Harmful algae》2008,7(4):523-531
Temporal variation in the type and abundance of dinoflagellate cysts in Manila Bay, Philippines, is established using 210Pb-dated sediment cores. At least 17 dinoflagellate cyst species, including those of the toxic species, Pyrodinium bahamense var. compressum, were identified. P. bahamense may have been present in the area since at least the 1920s. Total cyst density has increased beginning about 1988 to 1998 coinciding with records of P. bahamense blooms in the area. Heterotrophs have always dominated the cysts assemblage. These changes in the dinoflagellate record and the P. bahamense blooms in recent years may have been induced by the interplay of warmer temperatures, high rainfall leading to higher river discharge and less turbulent waters due to passage of few tropical cyclones. 相似文献
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Eve Galimany Inke Sunila Hlne Hgaret Montserrat Ramn Gary H. Wikfors 《Harmful algae》2008,7(5):702-711
Mussels (Mytilus edulis) were exposed to cultures of the toxic dinoflagellate Alexandrium fundyense or the non-toxic alga Rhodomonas sp. to evaluate the effects of the harmful alga on the mussels and to study recovery after discontinuation of the A. fundyense exposure. Mussels were exposed for 9 days to the different algae and then all were fed Rhodomonas sp. for 6 more days. Samples of hemolymph for hemocyte analyses and tissues for histology were collected before the exposure and periodically during exposure and recovery periods.Mussels filtered and ingested both microalgal cultures, producing fecal pellets containing degraded, partially degraded, and intact cells of both algae. Mussels exposed to A. fundyense had an inflammatory response consisting of degranulation and diapedesis of hemocytes into the alimentary canal and, as the exposure continued, hemocyte migration into the connective tissue between the gonadal follicles. Evidence of lipid peroxidation, similar to the detoxification pathway described for various xenobiotics, was found; insoluble lipofuchsin granules formed (ceroidosis), and hemocytes carried the granules to the alimentary canal, thus eliminating putative dinoflagellate toxins in feces. As the number of circulating hemocytes in A. fundyense-exposed mussels became depleted, mussels were immunocompromised, and pathological changes followed, i.e., increased prevalences of ceroidosis and trematodes after 9 days of exposure. Moreover, the total number of pathological changes increased from the beginning of the exposure until the last day (day 9). After 6 days of the exposure, mussels in one of the three tanks exposed to A. fundyense mass spawned; these mussels showed more severe effects of the toxic algae than non-spawning mussels exposed to A. fundyense.No significant differences were found between the two treatments during the recovery period, indicating rapid homeostatic processes in tissues and circulating hemocytes. 相似文献
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Eco-physical conditions for the initiation and termination of Cochlodinium polykrikoides blooms in the South Sea of Korea are examined in this paper. The C. polykrikoides blooms generally occur in the sea near Naro-Do in late August every year. The submarine canyon near Naro-Do plays an important role in surface water intrusion from the open ocean driven by northeasterly winds. In late August, the monsoonal wind system in Korea changes from southwesterly to northeasterly winds, causing Ekman transport of warm, fresh Changjiang Diluted Water (CDW) into the sea near Naro-Do and creating a front between inland sea water and CDW. Along the front, aggregation of single C. polykrikoides cells in the CDW and downwelling yield favorable eco-physical conditions for development of C. polykrikoides blooms. When typhoons and strong northeasterly winds bring vertically well-mixed East China Sea water into the sea near Naro-Do again in September, the eco-physical conditions favor diatom growth and lead to the termination of C. polykrikoides blooms. 相似文献
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Oysters, Crassostrea virginica, from two populations, one from a coastal pond experiencing repeated dinoflagellate blooms (native), and the other from another site where blooms have not been observed (non-native), were analyzed for cellular immune system profiles before and during natural and simulated (by adding cultured algae to natural plankton) blooms of the dinoflagellate Prorocentrum minimum. Significant differences in hemocytes between the two oyster populations, before and after the blooms, were found with ANOVA, principal components analysis (PCA) and ANOVA applied to PCA components. Stress associated with blooms of P. minimum included an increase in hemocyte number, especially granulocytes and small granulocytes, and an increase in phagocytosis associated with a decrease in aggregation and mortality of the hemocytes, as compared with oysters in pre-bloom analyses. Non-native oysters constitutively had a hemocyte profile more similar to that induced by P. minimum than that of native oysters, but this profile did not impart increased resistance. The effect of P. minimum on respiratory burst was different according to the origin of the oysters, with the dinoflagellate causing a 35% increase in the respiratory burst of the native oysters but having no effect on that of the non-native oysters. Increased respiratory burst in hemocytes of native oysters exposed to P. minimum in both simulated and natural blooms may represent an adaptation to annual blooms whereby surviving native oysters protect themselves against tissue damage from ingested P. minimum. 相似文献