# Environmental forces shape the ecology of virulent parasites in coastal ecosystems

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA AT DAVIS · 2024 · $663,306

## Abstract

Few studies have characterized disease ecology questions for pathogens with robust environmental
stages that cross ecosystem boundaries. In recent decades, terrestrially derived protozoan infections have
been increasingly reported in marine mammals. Toxoplasma gondii and Sarcocystis neurona are common
pathogens in southern sea otters, but their definitive hosts are terrestrial (felids and opossums,
respectively). En route from their terrestrial definitive hosts to a marine animal, parasite stages are subject
to diverse environmental forces that determine whether they are effectively mobilized and sufficiently
viable to infect a marine host. Intriguingly, we found that the diversity of protozoa genotypes in sea otters,
including virulent strains, does not reflect parasite diversity in terrestrial hosts. We hypothesize that (i)
environmental forces drive selection of virulent protozoan strains in marine ecosystems; and (ii) virulent
parasite strains accumulate and persist in submarine vegetated habitats. Our objectives will generate
novel and diverse datasets for an integrative Bayesian modeling approach to test how land-sea
environmental forces shape the distribution, population structure and selection of virulent parasites in
coastal ecosystems. Objectives are designed to answer two questions: Q1: How do environmental forces
across land-sea habitats affect the genetic distribution, transport and survival of T. gondii and S. neurona in
the nearshore? And Q2: Are submarine vegetated habitats (kelp and seagrass) hot spots for transmission
of virulent pathogens for sea otters? By integrating field, genomics, stable isotope analysis and modeling
approaches across land-sea boundaries, this research will provide a new framework to understand how
habitat and climate dynamics shape the ecology of virulent pathogens in marine environments. Focusing
on kelp and seagrasses has the potential to yield transformative insight on infectious disease transmission
in the coastal ocean, with broad implications for diverse host-pathogen systems. Our fully mechanistic
model includes numerous ecological processes and incorporates the previously unrecognized importance
of submarine vegetation in concentrating pathogens and mediating predator-prey interactions that
determine marine host infection patterns. Results will thus represent a fundamental advance in our current
understanding of infectious diseases that cross coastal boundaries.

## Key facts

- **NIH application ID:** 11059728
- **Project number:** 1R01GM157739-01
- **Recipient organization:** UNIVERSITY OF CALIFORNIA AT DAVIS
- **Principal Investigator:** JONATHAN A. EISEN
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $663,306
- **Award type:** 1
- **Project period:** 2024-09-01 → 2028-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11059728

## Citation

> US National Institutes of Health, RePORTER application 11059728, Environmental forces shape the ecology of virulent parasites in coastal ecosystems (1R01GM157739-01). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/11059728. Licensed CC0.

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