Undergraduate Honors Theses

Thesis Defended

Spring 2018

Document Type


Type of Thesis

Departmental Honors


Ecology and Evolutionary Biology

First Advisor

Pieter Johnson


Cymothoid parasites have many deleterious effects on their hosts’ fitness. Atlantic menhaden (Brevoortia tyrannus) support the largest fishery on the Atlantic coast and are frequently parasitized by the cymothoid parasite Olencira praegustator. Despite their economic and ecological importance, this interaction has not been carefully explored. I investigated the relationship between O. praegustator and B. tyrannus across three sites in the salt marshes of South Carolina. Over a five-week period I collected 169 B. tyrannus and found that over 96% were infected (163/169). Of the six-uninfected fish, five exhibited signs of previous infection. When O. praegustator was present, it was removed with forceps and preserved on ice to be measured (mm) and weighed (g). Brevoortia tyrannus length (mm) was recorded. Sixty O. praegustator were female, nine of which were mature and gravid, and 103 were either male or in the transitioning phase from male to female. Using a Poisson distribution and chi-squared goodness-of-fit test, I found that the number of parasites per fish is non-random, with 162/169 B. tyrannus, harboring only one O. praegustator. A metric of pathology was also created to assess the external damage present on the operculum of B. tyrannus. Olencira praegustator length was negatively correlated with B. tyrannus operculum damage. Considering this high infection prevalence, the significant damage O. praegustator has on its hosts’ operculum, and the impairing effects other cymothoids have on their hosts, the relationship between B. tyrannus and this pervasive parasite should be considered in the future management decisions of this keystone species.

Available for download on Saturday, April 13, 2019