Allison M. Tracy
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Species Interactions and the Health of Coastal Foundation Species

Key words: Foundation species, working land and seascapes, ecosystem function

Oyster reefs are important for coastal ecosystems because they provide habitat and filter water. In the Chesapeake Bay, Crassostrea virginica is also a culturally and economically important species.

As a  postdoctoral fellow with Chesapeake Working Land and Seascapes at SERC, my research includes synthesizing historical data on oysters across the Chesapeake Bay to study how environmental conditions and species interactions are affecting oyster reefs in a changing ocean. I am also collecting data on species interactions and habitat quality on present-day oyster reefs through field studies. In addition to advancing our understanding of oyster ecology, my work aims to explore the impact of management on oyster reefs. 

While oysters are economically and ecologically important organisms, they are part of a broader ecosystem that includes working landscapes and seascapes. I am collaborating with terrestrial ecologists at SERC to bridge the land-sea interface and obtain a broader perspective on the impact of environmental change on the Chesapeake Bay watershed. 

Goals:
(1) To understand how the environment directly and indirectly impacts the health of a critical foundation species in the Chesapeake Bay.
(2) To evaluate the combined influence of the environment and management in oyster reef health.
(3) To restore the health and ecosystem services of vital coastal ecosystems.

Collaborators: Dr. Matthew Ogburn (@OceanOgburn); Dr. Kim Komatsu (@drkimkomatsu); Dr. Amy Hruska (@ecologist_amy); Zofia Knorek (@zofiaknorek); Smithsonian Working Land and Seascapes (@SmithsonianWls)

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Ecology & Evolution of Disease and Immunity

Key words: Host-parasite interactions, anthropogenic change, disease, eco-immunology, marine biology

I completed my PhD dissertation research on coral disease in the Harvell lab at Cornell University and in collaboration with Dr. Ernesto Weil (UPRM).

Coral co-infection

Co-infection is the reality for organisms living in a natural environment, but relatively little has been done to uncover the role of multiple parasites in the wild. Laboratory research points to important ways that parasites can interact within a host, which can lead to both ecological and evolutionary consequences. However, field studies of co-infection are sparse. My research on G. ventalina contributes to the emerging body of work on natural co-infections by evaluating the importance of environmental factors, host resources, and host immunity.
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Relevant publication:
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Octocoral co-infection as a balance between host immunity and host environment

Marine pollution

Host-parasite interactions are a normal part of healthy ecosystems, but environmental stressors can tip the balance in favor of the parasite. For example, conditions that lead to suppressed host immune function can allow a parasite to devastate a host population. In addition to the many large scale stressors that corals must contend with, there are important local stressors that further influence coral health. Pollution is a local stressor that can have devastating effects on marine life, but may also be more tractable to resolve at a local scale. One aspect of my dissertation research focuses on the combined effects of warming oceans and pollutants on disease in G. ventalina. I have also studied the relationship between pollution and disease in Scleractinian corals in Hawaii.
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Relevant publications:
Linking sewage pollution and water quality to spatial patterns of Porites lobata growth anomalies in Puako, Hawaii

Warming and pollutants interact to modulate octocoral immunity and shape disease outcomes

Eco-immunology

The host immune system is central to understanding the ecology and evolution of infectious disease. In addition, studying immunity in marine systems can shed light on the evolution of immunity given the ancient immune systems at work in many marine organisms, such as corals.

I am currently exploring the relationship between ecological factors and immune function in G. ventalina in the Caribbean.
One of my projects focuses on the role of the immune system during co-infection, while another investigates the unexpected outcomes of multiple stressors for coral immunity. I am using a combination of histology measurements and gene expression analyses to further the understanding of the immune system in G. ventalina. 
I have also studied immunity in sea stars, lobsters, seagrass, and cattle.
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Relevant publication:
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Up in Arms: Immune and Nervous System Response to Sea Star Wasting Disease

Coral microbial communities

Microbes can play an important role in both healthy and diseased corals. In addition to the microbes that cause disease, there are also microbes that are essential for healthy function and provide critical services to the coral host. I am interested in the role the environment plays in shaping these microbial communities and my dissertation research investigates this question in G. ventalina. In the future, I hope to further pursue questions about the microbial communities in complex environments and the ensuing effects on host populations over short and long time scales.
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Relevant publication:

​Persistent shifts in Caribbean coral microbiota are linked to the 2010 warm thermal anomaly

Marine disease in a changing ocean

Outbreaks of marine infectious diseases have caused widespread mass mortalities, but the lack of baseline data has precluded evaluating the hypothesis that disease is increasing in the ocean. My collaborators and I used a literature analysis to assess multi-decadal trends in marine disease across the recent decades of dramatic, global change. 

Relevant publication:
Increases and decreases in marine disease reports in an era of global change

Local adaptation and eelgrass wasting disease

In collaboration with Morgan Eisenlord, another Harvell lab graduate student, I am exploring the ecological and evolutionary context of eelgrass wasting disease in the Pacific Northwest. Given the spatial variation in disease prevalence and severity, we are interested in the potential for host and parasite local adaptation in this system. In this project, we are investigating the effects of host and strain variation at Friday Harbors Laboratories.

Additional Research Interests:

Invasive species, microbial metagenomics, local adaptation, ecology and evolution across scales

Parguera, Puerto Rico

Parguera, PR was the home base for my PhD research, which required extensive disease surveys and laboratory experiments. This research was made possible by the scientists and staff at Isla Magueyes, home of the Department of Marine Sciences for the University of Puerto Rico at Mayagüez. 
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