Ecological Determinants of Hematodinium Epidemics in the American Blue Crab

摘要0723662捕捞压力和栖息地退化是对沿海海洋生态系统的严重和普遍的威胁。已知这两者都会影响宿主移动、聚集、营养和死亡的动态，从而影响疾病的传播。人们对捕捞压力在促进海洋系统疾病出现和传播方面的作用知之甚少，尽管有间接证据表明，过度捕捞促成了若干海洋渔业疾病的出现。在这项研究中，来自弗吉尼亚海洋科学研究所和旧自治领大学的科学家将调查捕鱼压力和水质下降联合收割机如何与德尔玛瓦半岛的小型沿海河口水文相结合，以促进蓝蟹中致病寄生虫血甲藻的爆发。与这种疾病季节性爆发重叠的是对蓝蟹的密集捕捞，这通过清除更具抗病性的成年蟹来改变宿主的种群结构。因此，渔业增加了易感个体的相对数量，既直接通过去除成年人，也间接通过释放依赖密度的同类相食的幼鱼。潜在的平衡这些有害生物诱导的影响是快速增长率的蓝蟹，感染动态的季节性最低点，并在宿主感染的易感性，可能会限制疾病的传播的个体发生转变。在五年的工作中，该研究将：评估幼蟹和成年青蟹中血甲藻感染的流行率和空间分布与Delmarva半岛沿海海湾的拓扑结构的关系;确定青蟹渔业对健康和患病青蟹种群结构的影响;确定环境因素如何影响蓝蟹的感染，以及它们如何影响病原体的生活史和传播;阐明寄生虫生活史中的传播方式及其相对于宿主因素的效率;模拟控制疾病传播的基本机制，并预测与捕捞压力和环境压力因素变化有关的疾病爆发。这种疾病每年给国家和国际甲壳类渔业造成重大损失。这项研究将产生一个流行病学模型，能够将当地环境变化和捕捞压力与疾病动力学结合起来，广泛应用于几种有鳍鱼类和贝类种群。PI将继续大力参与该项目的本科生，研究生和博士后研究员的指导，包括参与VIMS和ODU的NSF REU计划。三个推广方案将包括与渔民、资源管理人员和环境管理人员举行年度会议，在当地高中开展推广方案，以及开发一个关于血吸虫的网站。

ABSTRACT0723662Fishing pressure and habitat degradation are severe and pervasive threats to coastal marine ecosystems. Both are known to impact the dynamics of host movement, aggregation, nutrition, and mortality, and therefore the transmission of disease. The role of fishing pressure in facilitating the emergence and spread of diseases in marine systems is poorly understood, although circumstantial evidence suggests that overexploitation has contributed to the emergence of disease in several marine fisheries. In this research, scientists from Virginia Institute of Marine Sciences and from Old Dominion University will investigate how fishing pressure and declining water quality combine with the hydrography of small coastal estuaries on the Delmarva peninsula to promote outbreaks of a pathogenic parasite, Hematodinium, in blue crabs. Overlying seasonal outbreaks of the disease is an intensive fishery for the blue crab, which alters the population structure of the host by removing the more disease-resistant adults. Thus, the fishery increases the relative number of susceptible individuals both directly, by removing adults, and indirectly by releasing juveniles from density-dependent cannibalism. Potentially counter-balancing these anthropogenically-induced effects are the rapid growth rate of the blue crab, a seasonal nadir in infection dynamics, and an ontogenetic shift in host susceptibility to infection that may constrain transmission of the disease. Over five years of work, the research will; assess the prevalence and spatial distribution of Hematodinium infections in juvenile and adult blue crabs in relation to the topology of coastal bays on the Delmarva Peninsula; determine the effect of the blue crab fishery on the population structure of healthy and diseased blue crabs; determine how environmental factors affect infections in blue crabs and how they affect the life history and spread of the pathogen; clarify the modes of transmission in the life history of the parasite and their efficiencies in relation to host factors; model the underlying mechanisms that control the spread of disease and predict outbreaks in relation to changes in fishing pressure and environmental stressors.In terms of broader impacts, the disease causes significant annual losses to national and international crustacean fisheries. This study will produce an epidemiological model capable of integrating local environmental change and fishing pressure with disease dynamics with broad application to several finfish and shellfish populations. The PIs will continue their strong involvement with mentoring of undergraduates, graduate students, and postdoctoral fellows in this project, including participation in NSF REU programs at VIMS and ODU. Three outreach programs will include an annual meeting with fishermen, resource managers and environmental stewards, an outreach program in local high schools, and development of a website on Hematodinium.