Tal Ben-Horin PhD

Atlantic Pigtoe, Dwarf Wedgemussel, Yellow Lance, and Tar River Spinymussel are four imperiled mussel species whose habitats lie within and may be affected by construction in the 540 project area. In order to address conservation needs for this species, tools must be developed that will allow researchers and natural resource managers to examine and monitor their health, including genetic fitness. In this project, we propose to analyze the current genetic diversity, population structure, and effective population sizes of these four species using molecular markers (single nucleotide polymorphisms, SNPs). These SNPs will then be used to establish standardized panels for each species that can be used to monitor genetic diversity and hatchery contribution as populations are augmented or reintroduced. We will also examine the overall fitness of the four target species within priority watersheds and hatcheries (Yates Mill Aquatic Conservation Center and NC Wildlife Resources Commission Conservation Aquaculture Center) by examining microbial, fungal, and viral communities through the use of histology and genetic sequencing, and using the field of ???-omics??? ( metabolomics, proteomics, transcriptomics) to define and compare levels of fitness between and within wild, restored, and hatchery held populations and individuals. After establishing a baseline of health and fitness, we will develop a suite of biomarkers and mussel health metrics that can be used to assess the health and fitness of mussel populations and that can be used to inform management actions, hatchery operations, and species restoration efforts. Finally, we will define and begin implementation of quantifiable conservation targets based on the tools developed in the previous two objectives. We will synthesize the research completed in the first two objectives to set measurable conservation targets for each of the four priority species through a use of various models and workshops. We then expand the techniques from objectives 1 and 2 to evaluate the conservation targets.

Atlantic Pigtoe, Dwarf Wedgemussel, Yellow Lance, and Tar River Spinymussel are four imperiled mussel species whose habitats lie within and may be affected by construction in the 540 project area. In order to address conservation needs for this species, tools must be developed that will allow researchers and natural resource managers to examine and monitor their health, including genetic fitness. In this project, we propose to analyze the current genetic diversity, population structure, and effective population sizes of these four species using molecular markers (single nucleotide polymorphisms, SNPs). These SNPs will then be used to establish standardized panels for each species that can be used to monitor genetic diversity and hatchery contribution as populations are augmented or reintroduced. We will also examine the overall fitness of the four target species within priority watersheds and hatcheries (Yates Mill Aquatic Conservation Center and NC Wildlife Resources Commission Conservation Aquaculture Center) by examining microbial, fungal, and viral communities through the use of histology and genetic sequencing, and using the field of ????????????????-omics??????????????? ( metabolomics, proteomics, transcriptomics) to define and compare levels of fitness between and within wild, restored, and hatchery held populations and individuals. After establishing a baseline of health and fitness, we will develop a suite of biomarkers and mussel health metrics that can be used to assess the health and fitness of mussel populations and that can be used to inform management actions, hatchery operations, and species restoration efforts. Finally, we will define and begin implementation of quantifiable conservation targets based on the tools developed in the previous two objectives. We will synthesize the research completed in the first two objectives to set measurable conservation targets for each of the four priority species through a use of various models and workshops. We then expand the techniques from objectives 1 and 2 to evaluate the conservation targets.

Recent years have seen recurring spring mortality events impact oyster fisheries and aquaculture throughout North Carolina and locations all across the Southeast. Mortality approaching 30% is common, and in some years has exceeded 85% of oysters planted at numerous sites across North Carolina??????????????????s Sounds and the lower Chesapeake Bay. Most reports are from adult, sub-market sized triploid oysters, but wild and cultured diploids, as well as smaller seed oysters, have also seen similarly timed mortality events. These events do not seem to be associated with known oyster pathogens and disease but do seem to follow large rain events in the spring. The only unusual sign of pathology is increased inflammation in the gills, and the timing of these mortality events corresponds with seasonal peaks in gametogenic development in diploids. These observations suggest that oyster physiology and energetics interact with water quality changes and environmental stress to drive pathology. Our objective is to test how metabolic changes in oysters through the spring and summer drive oyster microbiota and pathology. We will quantify these changes across eight sites, six in North Carolina and two in Virginia, using hatchery-produced diploid and triploid oyster lines, testing whether triploid oysters are more sensitive to physiological changes and spring mortality events as compared to diploids. Our goal is to identify metabolic processes and microbes associated with spring mortality events, which will allow us to better identify water quality risks to North Carolina oyster fisheries and aquaculture while assessing how to move industries forward in the face of continued spring mortality.

Disease constrains sustainable aquaculture production. Oyster hatcheries and breeding programs have responded by developing disease resistant oyster stocks, which has proven to be an effective management tool for several diseases (D????????gremont et al. 2015). Selectively-bred oysters resist infection with diseasecausing parasites (Ben-Horin et al. 2018a) and even tolerate disease impacts by continuing to survive even when infected (Proestou et al. 2016). However, our recent work indicates that disentangling genetic variation for either disease resistance or disease tolerance can be a complex process for oyster hatcheries and breeding programs. For example, resistance to the endemic oyster parasite Perkinsus marinus covaries with tolerance to the disease this parasite causes, a fatal condition known as dermo disease. That is, selectively-bred oysters that survive and perform well when faced with dermo disease do little to resist P. marinus infection. In addition, by maintaining oyster stocks that perform well and survive when faced with disease, we are finding that oyster hatcheries and breeding programs effectively select for tolerance, and not necessarily resistance. This can often lead to counterintuitive outcomes when disease impacts extend beyond individual oyster farms to entire oyster populations throughout estuary ecosystems (Ben- Horin et al. 2018b). When aquaculture production relies on oysters bred to tolerate disease but not resist infection, disease prevalence and its impact increase in cultured oyster populations and in wild oyster populations nearby. With dermo disease impacts predicted to increase with ocean warming (Ford & Smolowitz 2007; Burge et al. 2014), it is imperative that we take an integrative approach to maximize aquaculture production while minimizing impacts to surrounding marine ecosystems. We aim to integrate laboratory experiments quantifying resistance and tolerance in hatchery and wild oyster stocks with traitbased epidemiological models to predict how selective breeding influences dermo disease and oyster performance under varying environmental conditions and its driving influence on disease dynamics. We have developed this proposed research in collaboration with another group led by Dr. Fulweiler submitting a pre-proposal to RI Sea Grant to then test these predictions with mesocosm experiments varying temperature to mimic the long-term expected rise in coastal water temperatures with climate change. Our parallel approach integrating targeted laboratory experiments, dynamic models, and data collected through mesocosm experiments will improve our capacity to predict and forecast host-parasite dynamics and its consequences for oyster performance and sustainable aquaculture production in a changing ocean.

Cyanobacterial Harmful Algal Blooms (CHABs) adversely affect estuaries and marine sounds as excess biomass leads to discoloration, odor issues, decreased oxygen levels, and subsequent fish kills. Concerns about exposure risks from cyanobacterial toxins through drinking water and food web transfer via shellfish have risen dramatically throughout the world. These concerns have also become a focal point in North Carolina, where efforts to restore natural oyster reefs and the emerging oyster farming industry could be heavily impacted, the latter of which is expected to grow to $100 million by 2030. The extent to which shellfish serve as biotoxin vectors to humans is unknown despite CHABs being a recurrent phenomenon and toxin presence reported throughout North Carolina waters as well as across marine and estuarine food webs. Phycotoxins harm humans in varying ways and the lack of data on toxin loads in shellfish impedes assessing human exposure risks, inhibiting mitigation strategies and the development of forecasting tools. This pilot project will address these knowledge gaps by leveraging CHHE core resources to build existing and new collaborations between scientists and oyster industry partners across North Carolina. We aim to identify dominant toxin-producing cyanobacteria species in North Carolina??????????????????s shellfish growing areas and quantify toxin loads in farm-raised oysters. Developing this collaborative information-gathering framework will be crucial to develop follow-up studies addressing links between environmental variability and public health in coastal food production systems.

Starting in 2012, bay scallops in North Carolina were observed to be infected by an unidentified macroparasite. This same parasite has recently been observed infecting bay scallops on the west coast of Florida. Preliminary phylogenetic analysis of DNA sequence data isolated from infected North Carolina and Florida scallops indicates that the parasite is a trematode (fluke) in the family Didymozoidae (superfamily Hemiuroidea), and that it forms a well-supported clade with another didymozoid from Australia. The trematode is using the scallop as a first intermediate host, reproducing asexually within the host??????????????????s gill tissue. Histopathological examination reveals that the trematode infects the afferent vessels of the host??????????????????s gill filaments, greatly distorting the proximal portion of the gill. Swollen afferent vessels, which visibly squirm in freshly-collected animals, contain multiple germinal sacs, each of which contains thousands of cercariae. Because the parasite infects a species of great fisheries interest in a manner that is obvious to the naked eye, and yet was not observed before 2012, we suspect that it is a recently-introduced species, and might be increasing in prevalence. Although it is safe to eat infected scallops, the parasite could still impact fisheries interests. Trematodes typically castrate their first intermediate hosts, suggesting that the parasite could impact wild scallop populations via reduced fecundity. The parasite could also impact fisheries interests by reducing yield and rendering infected scallops unappetizing. Because the newly-discovered trematode represents a novel threat to an already-imperiled fishery, it merits further investigation. This project addresses six fundamental research objectives: 1) identify spatiotemporal patterns in the prevalence of Didymozoidae trematodes in wild and cultured scallops; 2) better understand this parasite??????????????????s life cycle 3) and genetic variation along its observed range; test this parasite??????????????????s effects on 4) host metabolism and 5) fecundity; and 6) understand the impacts of climate change and scallop aquaculture expansion on trematode infections in wild and cultured scallops.