Crustacean parasites of fishes in Lake Kariba, Zimbabwe, preliminary results

Abstract

During a survey of fish ectoparasites in Lake Kariba (Zimbabwe), two crustaceans were often encountered . Dolops ranarum (Branchiura), parasite of the body, mouth and gill chamber, infected mostly cichlids, the catfish Clarias gariepinus, Synodontis zambezensis and two Mormyrids . Among cichlids clear host preferences were shown . No seasonal variations could be detected in the infections . D . ranarum parasitized predominantly fish above 15 cm in standard length . Lamproglena monodi (Copepoda) parasitized only the gills of cichlids with a preference for Serranochromis codringtonii, S . macrocephalus and Tilapia rendalli . Small fish were seldom infected . Seasonal variations of the prevalence occurred, the hot season being the less favourable . Few other crustaceans were found during the survey : a single specimen of Lamproglena hemprichii on the gills of the tigerfish, Hydrocynus vittatus ; three specimens of Afrolernaea longicollis, one found on the gills of Hippopotamyrus discorhynchus and two on the gills of Mormyrops deliciosus ; a hundred of Ergasilus mirabilis in a specimen of H. discorhynchus .

Distribution pattern of crustacean ectoparasites of freshwater fish from Brazil

“…We found 53 species of Copepoda, 15 species of Branchiura and 8 species of Isopoda. Several species of these taxa are also components of assemblies of ectoparasites of freshwater fish in other regions of the world (FRYER, 1968;DOUELLOU & ERLWANGER 1994;BOXSHALL & HALSEY, 2004;POLY, 2008;BOXSHALL & DEFAYE, 2008). However, most of these parasitic crustacean species occurred in hosts within Characiformes and Siluriformes, especially in species within Characidae, Serrasalmidae and Pimelodidae.…”

“…Copepoda was the parasitic taxon most frequently associated with freshwater fish in Brazil, among the samples examined, with 43 species in the family Ergasilidae and dominance of Ergasilus spp., along with the presence of eight species in the family Lernaeidae. Many species of copepods have free-living infective stages, thus possessing morphological and behavioral adaptations that increase the likelihood of transmission (FRYER, 1968;DOUELLOU & ERLWANGER, 1994;THATCHER, 2006). In the Neotropical region, Copepoda is the third largest taxon of crustaceans parasitizing freshwater fish of different environments and ecosystems (LUQUE & POULIN, 2007).…”

“…Many parasitic crustacean species have preferences for particular sites on hosts in comparison with others (FRYER, 1968;DOUELLOU & ERLWANGER, 1994;CARVALHO et al, 2004;THATCHER, 1998THATCHER, , 2006TAVARES-DIAS et al, 2011SMIT et al, 2014), but this degree of restriction varies among parasite species. Thus, we found that while the lernaeid P. gamitanae infested only the oral cavity and gills of its host characids, L. cyprinacea is a parasite with low specificity that prefers the integument and gills of its hosts.…”

“…These results clearly showed a change of site preference in C. macropomum, for some unknown reason. Both feeding and attachment sites probably play important roles in the distribution of native ectoparasite crustaceans in host fish (FRYER, 1968;DOUELLOU & ERLWANGER, 1994;THATCHER, 1998THATCHER, , 2006CARVALHO et al, 2004;SMIT et al, 2014). Thus, one important reason why parasites prefer specific sites may relate to more effective use of resources such as food, the host species available and the vulnerability of the attachment site.…”

“…Ectoparasitic crustaceans attack the gills, oral cavity, nostrils and/or integument of fish (FRYER, 1968;DOUELLOU & ERLWANGER, 1994;CARVALHO et al, 2004;TAVARES-DIAS et al, 2014), which may give rise to a variety of damage to their hosts. Some species of these parasites may have both direct and indirect effects on fish populations, especially through causing reductions in the hosts' growth and reproduction rates, along with mortality among these fish.…”