Northward Expansion of Bopyrid Isopod Parasites in Daggerblade Grass Shrimp in Cape Cod, MA

Abstract

The daggerblade grass shrimp, Palaemonetes pugio, is among the most abundant species of shrimp inhabiting estuaries along the East Coast and the Gulf of Mexico. They play an important trophic role as epiphyte grazers, detritivores, and prey for many commercially and ecologically important species. Due to the vital role they play in these estuarine environments, any change in their population has the potential to alter community composition and disrupt ecosystem functioning. Grass shrimp are also the definitive host of bopyrid isopod Probopyrus pandalicola, an ectoparasite that decreases energy availability and prevents reproduction by sexually sterilizing its female host, potentially decreasing shrimp populations. The bopyrid isopod has been reported in grass shrimp in the Southeastern U.S at rates ranging from .001% to 5.7% but has not been documented north of Maryland. This project documents the prevalence of P. pandalicola parasitized P. pugio in Cape Cod, Massachusetts after receiving personal observations of bopyrid isopods parasitizing grass shrimp at Long Pasture Wildlife Sanctuary in 2019. Findings in this study indicate a northward expansion of P. pandalicola in a novel host population of P. pugio at rates higher than previously reported in the literature. Based on this research, we are working on establishing a long-term monitoring program with Long Pasture Wildlife Pasture to manage this population of bopyrid isopods.