Research ProjectEcology of Marine Parasites

Diversity, Distribution, and Host Specificity of Marine Parasites and Disease

  • Kristy and Katrina collect oysters at Punta Chame, Panama.

    Dr. Katrina Lohan and Kristina Hill-Spanik collecting oysters off rocks at Punta Chame, Panama. Photo credit: Carmen Schlöder

  • Kristy, Greg, and Mark looking for oysters in Panama

    Kristina Hill-Spanik and Drs. Greg Ruiz and Mark Torchin collecting oysters from mangroves at Punta Caracol, Panama. Photo credit: Katrina Lohan

  • Ruth DiMaria sampling diseased portions of seagrass leaves from the Indian River Lagoon, Florida.

    Ruth DiMaria sampling diseased leaves from seagrasses collected from the Indian River Lagoon, Florida. Photo credit: Katrina Lohan

Project Goal

We are examining patterns of parasite diversity and distribution, the host and habitat specificity of different parasites, the ecology of multi-host systems, including potential environmental reservoirs, and finally, the genomic and population genetic diversity of different species and strains of marine parasites.


We are examining parasite diversity and distribution at multiple geographic scales. The hosts we study, bivalves and seagrasses, are model organisms for this work, because both groups include parasites with varying levels of host specificity, allowing us to examine the evolutionary and ecological mechanisms associated with a parasite’s ability to infect many different host species. Parasites are generally much smaller than their hosts, making them notoriously difficult to identify. Some of the larger metazoan parasites* can be viewed using a microscope. However, even most of these larger parasites require additional research tools for identification to species level. Thus, we primarily use DNA markers to identify parasites and examine their population genetic diversity* and structure. Some of the DNA tools we use include Sanger and high throughput sequencing* (454 and Illumina platforms), metabarcoding*, microsatellites*, and phylogenetics*.

Some of our work focuses on the parasites in bivalves living along the coasts of Panama, particularly those around the Panama Canal, a major hub for global shipping networks, because ships may contribute to the spread of parasites on a global scale. Another aspect of our research examines the parasite diversity associated with commercial ships to determine their contribution to parasite dispersal, invasion, and the on-going threat of emerging infectious diseases in the world’s oceans.

As part of this research, we are also examining the distribution and severity of the diseases caused by these parasites, which can range dramatically across geographic locations and hosts.

Feature Stories

Molecular Data Leads to Surprising Discoveries about Oysters in Panamanian Waters. By Katrina Lohan and Monaca Noble. May 2015


KM Pagenkopp Lohan, KM Hill-Spanik, ME Torchin, M Aguirre-Macedo, RC Fleischer, & GM Ruiz (2016) Richness and Distribution of Tropical Oyster Parasites in Two Oceans. Parasitology, 143: 1119-1132.

KM Pagenkopp Lohan, RC Fleischer, KJ Carney, KK Holzer, & GM Ruiz (2016) Amplicon-based pyrosequencing reveals high diversity of protistan parasites iships’ ballast water: implications for biogeography and infectious diseases. Microbial Ecology, 71 (3): 530-542.

KM Pagenkopp Lohan, KM Hill-Spanik, ME Torchin, EE Strong, RC Fleischer, & GM Ruiz (2015) Molecular phylogenetics reveals first record and invasion of Saccostrea species in the Caribbean. Marine Biology, 162: 957–968.


Katrina Lohan

Term Definition
Metazoan parasites  Multicellular eukaryotic parasites   
Population genetic diversity  The total number of genetic characteristics in the genetic makeup of a species population.
High throughput sequencing  Faster and less expensive methods of sequencing and analyzing large genomes.
Metabarcoding A method of DNA barcoding that uses universal PCR primers to identify DNA from a mixture of organisms 
Microsatellites A microsatellite is a tract of repetitive DNA in which certain DNA motifs (ranging in length from 2–5 base pairs) are repeated, typically 5-50 times.
Phylogenetics Phylogenetics is the branch of life science concerned with the analysis of molecular sequencing data to study evolutionary relationships among groups of organisms.