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While many harmful algal blooms have been associated with increasing eutrophication, not all species respond similarly and the increasing challenge, especially for resource managers, is to determine which blooms are related to eutrophication and to understand why particular species proliferate under specific nutrient conditions. The overall goal of this brief review is to describe why nutrient loads are not changing in stoichiometric proportion to the "Redfield ratio", and why this has important consequences for algal growth. Many types of harmful algae appear to be able to thrive, and/or increase their production of toxins, when nutrient loads are not in proportion classically identified as Redfield ratios. Here we also describe some of the physiological mechanisms of different species to take up nutrients and to thrive under conditions of nutrient imbalance. 相似文献
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B.G. Crespo O. Espinoza-GonzálezI.G. Teixeira C.G. CastroF.G. Figueiras 《Estuarine, Coastal and Shelf Science》2011,94(2):172-181
Microbial plankton biomass, primary production (PP) and phytoplankton growth rates (μ) were estimated along the NW Iberian margin during an upwelling relaxation event. Although the interaction between wind forcing and coastline singularities caused high spatial variability in PP (0.4-8.4 g C m−2 d−1), two domains (coastal and oceanic) could be distinguished regarding microbial plankton biomass and μ. At the coastal domain, with higher influence of upwelling, diatoms showed an important contribution (27 ± 17%) to total autotrophic biomass (AB). Nonetheless, AB was dominated by autotrophic nanoflagellates (ANF) at both realms, accounting for 62 ± 16% and 89 ± 6% of the integrated AB at the coastal and oceanic domain respectively. AB and heterotrophic biomass (HB) were significantly higher at the oceanic than at the coastal domain, with both biomasses covarying according to HB:AB = 0.33. Whereas the low phytoplankton carbon to chlorophyll a ratio (Cph:chl a = 38 ± 3) and the high μ = 0.54 ± 0.09 d−1 registered at the coastal stations suggest that phytoplankton was not nutrient limited at this domain, the values (Cph:chl a = 157 ± 8; μ = 0.17 ± 0.02 d−1) recorded at the oceanic domain point to severe nutrient limitation. However, the high Fv/Fm fluorescence ratios (0.56 ± 0.09) measured at the sea surface in the oceanic domain suggest that nutrient limitation did not occur. To reconcile these two apparently opposite views, it is suggested the occurrence of mixotrophic nutrition of ANF, with heterotrophic nutrition supplying about 75% of carbon requirements. 相似文献
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YANG Xiuxia * ZENG Xiaoqi JI Yupeng LIU Qun Fisheries College Ocean University of China Qingdao P..R.China 《中国海洋大学学报(英文版)》2003,2(1)
1 Introduction Microalgae ,asthefirstlinkofmarinefoodchain ,canbeusedfortheaccumulationofpolyunsaturatedfattyacids (PUFAs) ,whichhavebeenshowntobeofmajorimportancenotonlyinthe preventionofhu man’sheartandcirculatorydiseases (DyerbergandJorgensen ,1982 ;Marcus ,1985 )butalsoinaquacul tureasincipientfeed (Sakamotoetal.,1998) .How ever ,thePUFA productivitiesbymicroalgaearelowincomparisonwithbacteriaandfungi.TherearetwopossiblewaysinpromotingthePUFA productionofmicroalgae.Oneistoobtaint… 相似文献
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为进一步研究、探讨和开发海洋硅藻,研究了醋酸对海洋硅藻海链藻(Thalassiosira sp．)生长的影响。结果表明,pH值为8．0～9．0时,以醋酸调节pH值时海链藻的生长率高于用盐酸调节pH值时的生长率。1次性添加10～100mg／L醋酸都可促进海链藻生长;每日1次添加5～60mg／L的醋酸时,可明显提高海链藻的生长率。 相似文献
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