Examining Population Genetics and Disease Incidence in Local Grass Shrimp Species

Abstract

In coastal ecosystems, Palaemon spp. (P. pugio, P. vulgaris, and P. intermedius) are ecologically significant species that serve as food sources and bioindicators. They may also be potential reservoir species for an emerging pathogen that infects commercially valuable penaeid shrimp species in coastal North Carolina (NC). Shrimp Black Gill (sBG) is a pathology caused by the ciliate parasite Hyalophysa lynni. This disease has been shown to negatively impact commercial shrimp populations in Georgia and South Carolina, but it represents a recent climate-induced spread into temperate waters, including North Carolina. By analyzing grass shrimp species collected from NC estuarine populations in the Pamlico Sound, my investigation aimed to (1) determine the species composition of grass shrimp and gene flow among populations, and (2) use microscopy and PCR-based tools to determine the proportion of shrimp infected (i.e., infection prevalence) by Hyalophysa lynni. Altogether, genetic tools allowed me to identify the three species of grass shrimp across five sites in the Pamlico Sound, and I found P. pugio to be in the greatest proportion among all grass shrimp at these sites. I also found all three grass shrimp harbored the ciliate that causes sBG. Because grass shrimp inhabit Pamlico Sound year-round, they may serve as reservoir hosts for commercially valuable species, like Penaeid shrimp and blue crabs, which migrate into the Sound at certain times of the year. My research helps to provide a better understanding of the species’ composition, migration, and disease incidence of grass shrimp in our local estuaries. By understanding disease prevalence and species movements in these systems, we can better understand the impact of emerging diseases and use these baseline data to investigate transmission, infection, and long-term impacts of sBG in the Pamlico Sound in the future.