Effects of climate change on shellfish and eelgrass health Seagrass and shellfish frequently co-occur along the coast. We are investigating how these ecosystem engineers interact to alter each other's health and how climate change may be affecting these interactions. In an experiment run at the Friday Harbor Labs, we found that eelgrass was healthier at high pH, and in the presence of oysters. Oysters also had higher growth rates in the presence of eelgrass, which raised daytime pH. We are continuing to investigate these interactions under different scenarios in both the lab and the field.
Collaborators: Colleen Burge, Chelsea Bergman, Lindsay Alma Previous funding: Center for Excellence in Aquatic Epidemiology at the Atlantic Veterinary College Current funding: NSF Ecology and Evolution of Infectious Diseases
Epidemiology of wasting disease in temperate seagrass beds
Measuring wasting disease along an intertidal transect
Wasting disease has been associated with epidemics in temperate eelgrass beds, which have been associated with dramatic population decline and extinction. The etiological agent of disease, Labyrinthula zosterae, is an opportunistic pathogen, and only causes disease in a subset of cases. It is unknown what factors cause this pathogen to switch from being commensalist or mildly pathogenic to highly pathogenic. Our research aims to: 1) characterize demographic patterns in wasting disease prevalence and severity 2) investigate the effect of biotic and abiotic stressors (e.g., herbivory, temperature, water quality) on the prevalence of wasting disease 3) investigate and model transmission dynamics in eelgrass beds Collaborators: Drew Harvell, Eileen Hoffman, Colleen Burge, Lindsay Alma, Becca Maher, Shalya Ferreiro, Olivia Graham, Chelsea Bergman Previous funding: Center for Excellence in Aquatic Epidemiology at the Atlantic Veterinary College, Friday Harbor Labs, Research Coordination Network in the Ecology of Infectious Marine Diseases (NSF) Current funding: NSF EEID (2021-2024)
Black eye syndrome: And emerging disease of Snow Crab in the Eastern Bering Sea
Snow and Tanner crabs, which collectively comprise the biggest crab fishery in Alaska, are experiencing a rapid and recent increase in a suspected disease. First identified in 2017, this condition, named black eye syndrome (BES), is characterized by subtle changes in eye pigmentation in the eyestalk in early stages, and lesions, loss of function, retinal collapse and erosion of the eyestalk in later stages. We have composed a multidisciplinary team with expertise in crustacean diseases, stock management, computational biology, epidemiology, and oceanography to: validate at-sea visual assessment of BES severity against laboratory-based microscopy, evaluate the hypothesis that the eyestalk microbiome is shifting towards a suite of more pathogenic bacteria as BES progresses, experimentally quantify the impact of temperature on BES incidence, progression, and mortality, identify demographic, physiologic, and environmental correlates of BES prevalence using (a) a 5-year dataset on BES prevalence collected across the Eastern Bering Sea and (b) oceanographic models of sea bottom temperature and carbonate chemistry.
Collaborators: Ben Daly, Hamish Small, Justin Greer, Darren Pilcher, Reyn Yoshioka, Ted Meyers Funding: North Pacific Research Board (2021-2024)
Epidemiology of infectious diseases in Pacific Herring The population of Pacific herring in Prince William Sound, Alaska, declined by more than 75% in 1993, just 4 years after the Exxon-Valdez oil spill. Since that time, the population has failed to recover and has been experiencing low recruitment. Numerous hypotheses have been put forward about the causes for the lack of recovery of this critical forage fish. Potential drivers include climate change, increased predation and competition from pink salmon, decreased food availability leading to starvation of age-0 herring and disease. While there is some evidence that the first three hypotheses are contributing to the lack of recruitment, the evidence is inconclusive; there is no ‘smoking gun’. The role of disease in failed recruitment is not well quantified. Viral hemorrhagic septicemia (VHS), viral erythrocytic necrosis (VEN) and Ichthyophoniasis are all capable of causing mortality in Pacific herring and have been found with varying prevalence in PWS. While a member of the herring research and monitoring program for Prince William Sound, I ran experiments and models to investigate how changing environmental conditions and disease may be interacting to affect this population. At the Bigelow labs, I am continuing to do some of the modeling work. Collaborators: Paul Hershberger, Scott Pegau, John Trochta and other members of the Herring Research and Monitoring Program Current funding: Exxon Valdez Oil Spill Task Committee (2018-2023) Past funding: North Pacific Research Board
Temperature, molting phenology and epizootic shell disease in American lobster
In 1998, the population of lobsters in Southern New England began to decline. At the same time fishermen began to see lobsters with lesions in their shells. While shell disease is an occasional, chronic, issue in lobsters, this new form of epizootic shell disease (ESD) was unusual in its severity and association with severe population declines. Incidence of ESD has since increased and this fishery is now considered collapsed, There are concerns, corroborated by field evidence and forecasts that ESD is spreading northwards into Gulf of ME lobsters. In collaboration with John Hoenig and Jeff Shields, I examined a 35 year mark-recapture dataset of lobsters in the South New England population. We used this unique dataset to: 1) Quantify the effect of the disease on populations and identify vulnerable life stages 2) Identify environmental drivers of disease 3) Build a model of ESD which can be used to simulate the effects of proposed management strategies and projected environmental conditions on lobster populations
We are currently collaborating with resource managers in Maine and Massachusetts to evaluate the future risk of ESD due to warming and altered molting phenology (resulting from seawater warming).
Current collaborators: Melissa Rocker (Bigelow), Kirsten Johnston (Bigelow), Reyn Yoshioka (Bigelow), Nick Record (Bigelow), Kathleen Reardon (Maine Department of Marine Resources), Heather Glon (Maine Department of Marine Resources), Tracy Pugh (Massachusetts Division of Marine Fisheries) Previous funding: NOAA Saltonstall-Kennedy, Ocean Frontiers Institute Current Funding: Sea Grant
Past Research projects
Epidemiology of sea louse infestations and implications for effective control
These ballan wrasse eat sea lice off of salmon
Sea lice (Lepeophtheirus salmonis) are an ectoparasite of Pacific and Atlantic salmonids and have been associated with declines of wild salmonids and increased mortality and morbidity of farmed salmon. As part of an international collaboration to investigate sustainable control strategies in salmon farming, we are using modelling techniques to evaluate strategies for managing these pests. We are addressing: 1) the effectiveness of cleanerfish in controlling sea lice 2) the influence of temperature and salinity in sea lice population growth and demography 3) the role of allee effects in limiting population growth 4) how mathematical modeling has improved our understanding of the epidemiology of sea louse on farmed and wild salmon Collaborators: Crawford Revie, Gregor McEwan, Ruth Cox, Marit Stormoen, Erin Rees Funding: the Atlantic Innovation Fund, the SALMODIS project
Gravid sea lice on a salmonid host
Evolution of pesticide resistance in sea lice
Pesticide resistance is a common problem for many invertebrate pests. Understanding the genetic and epigenetic mechanisms underlying pesticide resistance and the role of population structure in the evolution of resistance is critical for developing strategies to effectively control outbreaks and reduce selection for resistance. Sea lice have rapidly and repeatedly evolved resistance to chemotherapeutants that have been used to control epidemics on salmon farms. With sea lice as a model system, we used individual-based modelling to quantify: 1) how population structure, temperature and treatment strategies influence the rate of resistance evolution 2) trade-offs between management strategies designed to maximize the reduction of sea louse populations and to reduce the rate of resistance evolution Collaborators: Crawford Revie, Mark Fast, Gregor McEwan Funding: The Atlantic Innovations Fund
Influence of natural and anthroprogenic stressors on fungal infections in amphibians
Swabbing a Pacific chorus frog to test for Bd.
Batrachochytrium dendrobatidis (Bd) infections are associated with amphibian population decline and extinction on six continents. Very little is known about how environmental context influences this host-pathogen interaction. We used an experimental approach to explore how community composition alters the epidemiology and pathogenicity of Bd. We have quantified the effects of predation risk and competition on production of immune defenses against Bd and the implications of these changes for the development of chytridiomycosis in tadpoles and metamorphs. Antimicrobial peptides are one of the only immune defenses available to amphibians during metamorphosis and some antimicrobial peptides are able to inhibit the growth of Bd.
While doing this research we discovered several previously uncharacterized antimicrobial peptides in leopard frogs and wood frogs!
Collaborators: Rick Relyea, Louise Rollins-Smith, Laura Reinert, Mark Bier, John Hempel, Stephanie Gervasi, Andrew Blaustein Funding: NSF Predoctoral Fellowship, North American Benthological Society, Chicago Herpetological Society, Sigma Xi, Pymatuning Lab of Ecology
Direct and indirect effects of pesticides on amphibians
Low concentrations of insecticides influence leopard frog life history and survival
Pesticides and pesticide-pathogen interactions have been implicated in amphibian population declines, however the mechanisms for these effects are poorly understood. Pesticides may directly affect amphibian survival or indirectly influence amphibian fitness through trait- and density-mediated trophic cascades. We quantified direct and indirect effects of insecticides on ephemeral ponds with a focus on wood frog tadpoles. We also examined the indirect effects of insecticides on susceptibility of wood frogs to Bd.
Collaborators: Rick Relyea Funding: NSF Predoctoral Fellowship, North American Benthological Society, Chicago Herpetological Society, Sigma Xi, Pymatuning Lab of Ecology