The problem of emerging infectious diseases is particularly acute in marine ecosystems where studies lag behind those in terrestrial systems. Reports of emerging diseases in marine organisms are increasing worldwide, particularly in coastal environments, where the evidence is compelling that these events are associated with the degradation of water quality and habitat integrity. Yet, few of these studies have produced epidemiological models capable of integrating local environmental change with disease dynamics, and none involve motile marine fauna. A lethal, pathogenic virus has recently been discovered that infects juvenile Caribbean spiny lobster (Panulirus argus) in the Florida Keys, the first virus reported for any species of lobster. Transmission of the disease is primarily via contact and infectivity is associated with ontogeny; juvenile lobsters are susceptible to infection, adults are not. A remarkable facet of the disease is that it not only kills infected individuals, but also alters the behavior of healthy individuals who are normally social, but actively avoid contact with diseased conspecifics. The underlying causes for the emergence of the disease remain a mystery, but human-caused transformations of nursery habitat and declining water quality in south Florida preceded its emergence. One hypothesis is that deteriorating water quality, including that anticipated with Everglades restoration, acts as a subtle stressor that compromises lobster resistance to infection and facilitates the spread of disease. At the same time, poor water quality alters nursery habitat structure, thereby indirectly influencing disease dynamics by increasing host encounter rates and thus disease transmission. Potentially counter-balancing the effects of these environmental changes are ontogenetic shifts in host behavior, susceptibility to infection, and avoidance of diseased individuals that may constrain transmission of the disease. This project will include an ambitious program of laboratory, field, and modeling research with the goal of building a predictive understanding of the multifaceted role that diminished habitat integrity plays in the spread of a viral disease among social animals in degraded coastal marine ecosystems. The project builds on prior NSF sponsorship and draws together the talents of a multidisciplinary group of scientists with experience in lobster biology, ecological modeling, invertebrate pathology, and molecular biology. Although the focus is on the emerging PaV1 virus in spiny lobster in Florida as a model system, the results of this project will provide a better understanding of the role of habitat structure, ontogenetic changes in host resistance, and host behavior in regulating disease transmission in natural populations subject to anthropogenic insult. The project objectives are: (1) To explore the underlying mechanisms that control the spread of disease and to predict viral prevalence in relation to changes in nursery habitat structure and water quality stressors by incorporating ontogenetic aspects of host behavior, susceptibility to disease, and disease transmission into the existing spatially-explicit, individual-based lobster population model. (2) To quantitatively test in mesocosm and field experiments the effect of altered nursery habitat structure on ontogenetic differences in host movement, host spatial distribution, and viral transmission. (3) To determine in laboratory experiments whether potential environmental stressors such as extreme temperatures and salinities, or poor water quality alter host suceptiblity to viral infection or infectivity. (4) To characterize in a laboratory study host disease states and to determine their prevalence in nature using molecular and histological techniques. Broader Impacts: This project will include continued involvement and cross-training of undergraduates, graduate students, and postdocs, including participation of undergraduates in NSF REU programs at VIMS and ODU. Association with local resource management agencies ensures that the basic science results of this project will find application in management decisions. The PIs will co-host a semi-annual one-day workshop in Key West for fishermen, scientists, environmental managers, and the interested public where recent scientific findings and environmental concerns in the Florida Keys will be discussed. Continued molecular work will yield new assays for detection of viral infected tissue, which may aid officials in monitoring the potential spread and shipment of infected lobsters around the world. Also, the modeling component will aid managers in predicting the spread of the disease in wild populations.
