Vol. 61, 2022
between a Copepod (Pharodes
tortugensis) and Small Reef-associated Gobies (Coryphopterus) in the British
Graham E. Forrester1,*,§
and Rachel J. Finley2,§
of Natural Resources Science, University of Rhode Island, Kingston,
Rhode Island 02881, USA. *Correspondence: E-mail: email@example.com
2Department of Natural Resources
Science, University of Rhode Island, Kingston, Rhode Island 02881, USA.
E-mail: firstname.lastname@example.org (Finley)
§GF and RF contributed
equally to this work.
Received 21 February 2021 / Accepted 4 May 2022
Communicated by Benny K.K. Chan
The effects of parasitic copepods
on free-living hosts are infrequently documented, and the copepod Pharodes tortugensis has remained
virtually unstudied since described. For the first time, we document
its host range in the British Virgin Islands (BVI), the prevalence and
intensity of infections on wild hosts, and its impacts on host
morphology and performance. Infections were observed on four benthic
gobies in the BVI (Coryphopterus
glaucofraenum, C. venezuelae,
C. dicrus and C. eidolon) but not on other host
species previously reported from other parts of the western Atlantic.
Infected gobies were widespread in the BVI (detected at 33 of 52 sites,
prevalence from 1–25%) but extremely rare elsewhere in the Caribbean
(detected at 2 of 16 sites, prevalence < 0.006%). As is typical of
macroparasite infections, P. tortugensis was over-dispersed in
BVI host populations (mean intensity = 4.7, range = 1–17). Infections
were most common in juvenile and female hosts, and rarely found in
larger male hosts. The copepods attach in the branchial chamber of the
goby; female copepods show high attachment fidelity to the ventral
surface of the chamber, while male copepods attached most often to the
first two gill arches and in the branchial chamber adjacent to the
female. Infections caused substantial damage to the host’s branchial
chamber and gill filaments. Parasitized gobies also had larger livers
and smaller gonads than unparasitized individuals of similar length.
The changes in organ mass of infected gobies were not sizeable enough
to affect total body mass, and host condition (the body-length vs.
body-mass relationship) was similar for gobies with and without
infections. Parasitized gobies were, however, significantly smaller in
body mass at a given age, reflecting slower overall growth. Effects of P. tortugensis on individual hosts
were broadly similar to those of other parasitic copepods that infect
fish gills and, for unknown reasons, the BVI appears to be a persistent
hotspot of infections on these goby hosts.
Key words: Coral
reef fish, Ectoparasite, Gill pathology, Host-range, Infection
intensity, Liver condition, Prevalence, Reproductive output.
Citation: Forrester GE, Finley RJ. 2022.
Host-parasite interactions between a copepod (Pharodes tortugensis) and small
reef-associated gobies (Coryphopterus)
in the British Virgin Islands. Zool Stud 61:32. doi:10.6620/ZS.2022.61-32.