Prevalence and effects of a parasitic trematode on the blue mussel, Mytilus edulis, in the Boston Harbor

K Garrett Evensen; Alexandra E Figueroa; Alyssa M Goncalves; Tiffany J Chan; Emily B Vu; Isaac Hounain; Helen C Poynton

doi:10.1016/j.exppara.2023.108624

Prevalence and effects of a parasitic trematode on the blue mussel, Mytilus edulis, in the Boston Harbor

Exp Parasitol. 2023 Nov:254:108624. doi: 10.1016/j.exppara.2023.108624. Epub 2023 Sep 26.

Authors

K Garrett Evensen¹, Alexandra E Figueroa², Alyssa M Goncalves³, Tiffany J Chan⁴, Emily B Vu⁵, Isaac Hounain⁶, Helen C Poynton⁷

Affiliations

¹ University of Massachusetts Boston, Boston, MA, 02125, USA. Electronic address: K.evensen001@umb.edu.
² University of Massachusetts Boston, Boston, MA, 02125, USA. Electronic address: A.Figueroa001@umb.edu.
³ University of Massachusetts Boston, Boston, MA, 02125, USA. Electronic address: Alyssa.Goncalves@umb.edu.
⁴ University of Massachusetts Boston, Boston, MA, 02125, USA. Electronic address: tchan0378@gmail.com.
⁵ University of Massachusetts Boston, Boston, MA, 02125, USA. Electronic address: emilybtvu@gmail.com.
⁶ University of Massachusetts Boston, Boston, MA, 02125, USA. Electronic address: Isaac.Hounain001@umb.edu.
⁷ University of Massachusetts Boston, Boston, MA, 02125, USA. Electronic address: Helen.poynton@umb.edu.

PMID: 37769835
DOI: 10.1016/j.exppara.2023.108624

Abstract

The blue mussel, Mytilus edulis, is a keystone species in the North Atlantic that plays critical roles in nutrient cycling, water filtration, and habitat creation. Blue mussel populations have declined significantly throughout the North Atlantic due to various factors, including habitat loss, pollution, increasing water temperature, and parasites. One parasite is Proctoeces maculatus, a digenetic trematode, which uses M. edulis as an intermediate host. This parasite causes reduced growth, castration, and death in mussels. The range of P. maculatus has expanded northward from Cape Cod, MA to Maine which may be associated with rising temperatures in the Gulf of Maine. To evaluate the negative impacts of P. maculatus on mussels, we analyzed its infections in M. edulis throughout the Boston Harbor, MA. P. maculatus was present in every population and time point analyzed, with approximately 50% of mussels in the harbor infected. The parasite reduced gonadal development in infected mussels, which could lead to decreased fecundity. Severe P. maculatus infections induced a stress response, indicated by increased HSP70 expression. We developed a non-destructive hemolymph-based assay to determine if mussels are infected with P. maculatus, thus speeding up the evaluation process and eliminating the need to sacrifice individuals. With P. maculatus' continued expansion northward, more mussel populations will be under threat from this parasite.

Keywords: Blue mussel decline; Gonadal development; Heat shock proteins; Hemolymph; Proctoeces maculatus; Trematode.