Record of Copepod Parasite (Pennellidae) in Buccal Cavity and Gill Arch of Cultured Groupers, Epinephelus spp. in Batam, Indonesia

The crustacean parasites are the most frequently encountered and cause significant economic loss in mariculture. These parasites infect fish fin, skin, gills, and buccal cavity. This study aims to describe copepod parasite in the buccal cavity of cultured groupers, Epinephelus spp., from Batam waters using morphological and molecular biology approaches. The tiger grouper, Epinephelus fuscoguttatus (Forsskal, 1775), and hybrid grouper, Epinephelus sp. showing lethargy and skin darkening were collected from sea cages. The parasite’s morphology was observed using light and scanning electron microscopes. The genomic DNA was isolated from the parasites and used as a template for amplification of cytochrome oxidase subunit-1 (Cox1) gene and followed by sequencing. The fish exhibited red nodules in the mouth cavity, on the lips, and gill arch in varying numbers and size of nodules. The copepodid, chalimus, and adult copepod stages were found from the nodule. Based on the presence of the oral cone, this parasite belonged to Siphonostomatoida order of copepods. Based on the structure of the caudal ramus with four long and four short setae, the first and second pair legs as biramous, and the third pair leg as uniramous, this parasite belonged to Pennellidae family of copepods. Basic local alignment search tool analysis of this Cox1 showed low homology within 80%, indicating that the DNA sequences of the parasite species were not reported in the GenBank. The unweighted pair group method using arithmetic average phylogenetic trees supported that this parasite belonged to the family Pennellidae. This is the first report on the pennellid parasite infection in the buccal cavity and gill arch of cultured groupers in Batam, Indonesia.

Consistent patterns of trophic niche specialization in host populations infected with a non-native copepod parasite

SUMMARYPopulations of generalist species often comprise of smaller sub-sets of relatively specialized individuals whose niches comprise small sub-sets of the overall population niche. Here, the role of parasite infections in trophic niche specialization was tested using five wild fish populations infected with the non-native parasite Ergasilus briani, a copepod parasite with a direct lifecycle that infects the gill tissues of fish hosts. Infected and uninfected fishes were sampled from the same habitats during sampling events. Prevalence in the host populations ranged between 16 and 67%, with parasite abundances of up to 66 parasites per fish. Although pathological impacts included hyperplasia and localized haemorrhaging of gill tissues, there were no significant differences in the length, weight and condition of infected and uninfected fishes. Stable isotope analyses (δ13C, δ15N) revealed that the trophic niche of infected fishes, measured as standard ellipse area (i.e. the isotopic niche), was consistently and significantly smaller compared with uninfected conspecifics. These niches of infected fishes always sat within that of uninfected fish, suggesting trophic specialization in hosts. These results suggested trophic specialization is a potentially important non-lethal consequence of parasite infection that results from impaired functional traits of the host.