EU-US ECOHAB. EC-NSF Cooperative Activity in Environmental Res: Mating Incompatibility Among Toxic and Non-Toxic Populations of Alexandrium: Ecological and Practical Implications

有害藻华（HABs）在美国和世界上都是一个严重且日益严重的问题。在与有害藻华有关的多种中毒综合征中，麻痹性贝类中毒（PSP）可以说是全球范围内最广泛和最严重的。在美国和欧洲，许多PSP暴发是由Alexandrium属的鞭毛藻（特别是tamarensis和minutum物种复合体中的鞭毛藻）引起的。亚历山大属植物的时空格局有几个值得注意的特点。首先，在过去的几十年里，由于自然和人类辅助的扩散机制，这两个复合体内的物种分布在地理上都有所扩大。其次，在这些复杂的环境中，既有有毒的品种，也有无毒的品种，有时这些物种的繁殖距离彼此相对较近。鉴于最近的结果，后一种观察结果尤其值得注意，这些结果表明，有毒和无毒的tamarense菌株可以交配并产生静止的囊肿，但从这些囊肿中萌发的细胞在试图分裂时迅速死亡。因此，至少该物种的某些品系存在生殖障碍。该项目的总体目标是研究亚历山大属tamarensis和minutum物种复合体的有毒和无毒成员之间的交配相容性。这将涉及美国和欧盟伙伴在欧盟-国家科学基金会环境研究合作活动下的实验室和实地研究的直接合作。具体目标是：1)建立和鉴定来自美国东北部和欧洲的其他有毒和无毒亚历山大菌培养物；2)确定tamarense和mintum毒株和无毒株的交配相容性；3)确定一个遗传标记，以区分有毒和无毒的minute；4)制定确定浮游细胞和囊的有毒/无毒基因型的方法；5)确定有毒和无毒的麻球绦虫和tamarense绦虫菌株的交配选择性；6)参加欧洲野外调查，绘制浮游生物和沉积物中的亚历山大菌种群图；7)利用生长率、放牧率和交配偏好数据来模拟各种入侵情景的结果，并评估引入无毒亚历山大菌作为控制或缓解水华策略的潜力。所提出的研究的科学价值是重要的，因为要探索的交配不相容可能解释在世界各地观察到的有毒和无毒亚历山大菌物种的分布，并直接关系到一种毒素类型入侵到另一种毒素领域的潜在成功，例如通过自然水流和风暴，或压载水排放。更广泛的影响也很显著。有害藻华对公众健康和沿海资源的有效利用构成严重威胁。除了通过压载水排放或其他人类辅助手段传播物种的实际影响外，还将研究一种对社会具有潜在价值的新型水华控制或缓解战略，即可以将一种无毒的亚历山大菌菌株以类似于释放不育雄性以控制害虫的方式引入有毒爆发的地区。其他广泛的影响包括加强欧盟-美国的科学家HAB网络，通过会议演讲、科学出版物和大众媒体上的文章交流结果，以及培训和教育年轻科学家。在后一种情况下，来自美国和欧盟的学生和博士后研究人员将在PI的实验室工作，由外部奖学金、欧盟基金、内部WHOI基金（夏季学生奖学金、少数民族培训奖学金）和REU（本科生研究机会）支持，为此将提交提案。PI一直高度重视研究和教育的整合，这个项目也不例外。

Harmful algal blooms (HABs) are a serious and growing problem in the US and the world. Among the multiple poisoning syndromes linked to HABs, Paralytic Shellfish Poisoning (PSP) is arguably the most widespread and significant on a global basis. Dinoflagellates within the genus Alexandrium (and in particular within the tamarensis and minutum species complexes) are responsible for many of these PSP outbreaks in the US and in Europe. Several characteristics of the temporal and spatial pattern of Alexandrium species are noteworthy. First, over the last several decades, the distribution of species within both complexes has expanded geographically as a result of natural and human-assisted dispersal mechanisms. Second, there are both toxic and non-toxic varieties of certain species within each of these complexes, and sometimes these bloom in relatively close proximity to each other. This latter observation is particularly noteworthy given recent results, which demonstrate that toxic, and non-toxic strains of A. tamarense can mate and produce resting cysts, but the cells that germinate from these cysts quickly die as they attempt to divide. A reproductive barrier thus exists for at least some strains of this species. The overall objective of this project is to investigate mating compatibilities among toxic and non-toxic members of the tamarensis and minutum species complexes of Alexandrium. This will involve a combination of laboratory and field studies in a direct collaboration between US and EU partners under the EC-NSF Cooperative Activity in Environmental Research. Specific objectives are to: 1) Establish and characterize additional toxic and non-toxic Alexandrium cultures from the northeastern U.S. and Europe; 2) Determine mating compatibility between toxic and non-toxic strains of A. tamarense and A. minutum; 3) Identify a genetic marker to distinguish between toxic and non-toxic minutum; 4) Develop methods to determine the toxic/non-toxic genotype of planktonic cells and cysts; 5) Determine mating selectivity of toxic and non-toxic A. minutum and A. tamarense strains; 6) Participate in European field surveys to map Alexandrium populations in the plankton and sediments; and 7) Employ growth rate, grazing rate and mating preference data to model the outcome of a variety of invasion scenarios and to evaluate the potential of introduced non-toxic Alexandrium species as a bloom control or mitigation strategy.The scientific merits of the proposed study are significant, as the mating incompatibilities to be explored may explain observed distributions of toxic and non-toxic Alexandrium species throughout the world and relate directly to the potential success of an invasion of one toxin-type into the domain of the other, such as through natural currents and storms, or ballast water discharge. The broader impacts are also significant. HABs represent a serious threat to public health and efficient utilization of coastal resources. In addition to practical implications with respect to species dispersal via ballast water discharge or other human-assisted means, a novel bloom control or mitigation strategy of potential value to society will be investigated whereby a non-toxic strain of Alexandrium could be introduced to an area subject to toxic outbreaks in a manner analogous to the release of sterile males to control insect pests. Other broad impacts include strengthening the EU-US HAB network of scientists, communicating results via conference presentations, scientific publications, and articles in the popular press, and training and education of young scientists. In the latter context, students and postdoctoral investigators from both the US and the EU will work in the PI's laboratory on this project, supported by outside fellowships, EU funds, internal WHOI funds (Summer Student Fellowships, Minority Traineeships), and REU (Research Opportunities for Undergraduates) support, for which proposals will be submitted. The PI has always placed a high priority on the integration of research and education, and this project will be no exception.