Research ProjectHow Humans Move Marine Parasites

  • Dr. Katrina Lohan with water sample from Punta Culebra, a site at the Pacific entrance to the Panama Canal.

    Dr. Katrina Lohan with water sample from Punta Culebra, a site at the Pacific entrance to the Panama Canal. Photo Credit Kristina Hill-Spanik

  • Sediment sample from Fort Sherman, Panama

    Sediment sample collected at Fort Sherman, a site near the Caribbean entrance to the Panama Canal. Photo Credit Dr. Carmen Schlöder

  • Sampling microbial communities on the hulls of ships

    The aftermath of divers sampling microbial communities on the hulls of ships. Photo Credit Dr. Ian Davidson

Project Goal

We are examining the role of humans in spreading marine parasites and disease in marine systems, primarily focusing on marine shipping as the mechanism for transporting these organisms. We are also attempting to understand the characteristics associated with successful parasite invaders to better understand their invasion risk.


Marine shipping is a major contributor to the spread of marine organisms, allowing these plants, animals, and algae to travel across vast distances that would be impossible for them to do without human assistance. Though microscopic organisms are much more abundant in the marine environment and likely to also be spread through marine shipping, due to their small size, these organisms are much less conspicuous and have not been well-studied in invasion biology. However, there are many examples of the devastating impacts that toxic and parasitic microbes can have when these organisms are introduced into new areas and capable of infecting hosts, including MSX disease in the Chesapeake Bay and crayfish plague in Europe.

Thus, our research on parasite invasions involves understanding the role of humans in spreading marine parasites, assessing the characteristics that make parasites successful invaders, and examining the underlying mechanisms that allow for successful parasite invasions. We examined the protistan communities, including the parasites and toxic taxa, associated with ballast water of commercial ships across multiple US coasts to assess the extend to which marine ships are dispersing these organisms, changing their global distributions and allowing for potential invasions. We are currently assessing the microorganisms, including parasites, associated with the biofilms on the hulls of these ships as well. As these organisms are small and hard to find and identify based on morphology*, we are using genetics, specifically metabarcoding*, to identify microbes in these samples. Finally, we are beginning to examine the characteristics and mechanisms that allow for successful parasite invasions using laboratory experiments to understand how parasites associated with ships can move from the ships to hosts in the surrounding environment.

Feature Stories

What Parasites are Hitching a Ride to the Chesapeake Bay in Ballast Water? By Katrina Lohan. February 3, 2014


KM Pagenkopp Lohan, RC Fleischer, KJ Carney, KK Holzer, & GM Ruiz (2017) Molecular characterization of protistan species and communities in ships' ballast water across three U.S. coasts. Diversity and Distributions.

KM Pagenkopp Lohan, RC Fleischer, ME Torchin, & GM Ruiz (2017) Protistan Biogeography: A Snapshot Across a Major Shipping Corridor Spanning Two Oceans. Protist, 168: 183-196.

KM Pagenkopp Lohan, RC Fleischer, KJ Carney, KK Holzer, & GM Ruiz (2016) Amplicon-Based Pyrosequencing Reveals High Diversity of Protistan Parasites in Ships' Ballast Water: Implications for Biogeography and Infectious Diseases. Microbial Ecology, 71(3): 530-542.


Dr. Katrina Lohan

Term Definition 
Morphology the branch of biology that deals with the form of living things and the relationships between their structures
Biogeography The branch of biology that studies the geographical distribution of species, traits, and ecosystems

A DNA-based method for rapidly identifying the community of organisms in a particular sample using a combination of PCR and high throughput DNA sequencing