Acanthochondria

Abstract: As part of integrated biological-effect monitoring, the parasite fauna of the flounder Platichthys flesus (L.) was investigated at five locations in the German Bight, with a view to using parasite species as bio-indicators. Over a period of 6 years, parasites from 30 different taxa were identified, but only 7 taxa of the parasite community occurred regularly at all locations and in sufficient abundance that they could be considered as potential indicator species. These species were the ciliophoran Trichodina spp., the copepods Acanthochondria cornuta, Lepeophtheirus pectoralis and Lernaeocera branchialis, the helminths Zoogonoides viviparus and Cucullanus heterochrous and metacercaria of an unidentified digenean species. Infection characteristics of these parasites are presented, with a comparison of the results from individual sampling periods and those of the long-term data set. Natural influences on the infection levels, such as temporal variations, habitat conditions and host-related factors, were evaluated. All of these parasite species showed significant differences in their infection levels between the Elbe estuary, as the most polluted site, and the less polluted coastal and marine locations: Helgoland, Outer Eider estuary and Spiekeroog, especially in the long-term data set. Gradual differences between the Elbe, the Outer Eider and Helgoland, which were not detected in individual sampling periods, also became evident in the pooled-data set. These were found in the prevalence of Trichodina spp., A. cornuta, Z. viviparus and C. heterochrous. Although salinity is considered as the most important natural factor, influencing the distribution pattern of the majority of the potential indicator species, infection levels of most of these species differed between locations with similar salinity conditions. Infection levels corresponded to a contamination gradient (Elbe > Inner Eider, Outer Eider > Helgoland) established across the locations. Seasonal variation in the infection parameters affected the spatial distribution of the copepod species Lepeophtheirus pectoralis and Lernaeocera branchialis. Annual variations are considered to occur in the range of natural variability, so no trend of increasing or decreasing infection levels of the parasites was found during the course of the study. This study underlined the idea that an analysis of fish-parasite fauna is very useful in ecosystem monitoring.

Abstract: Seasonal changes in the levels of copepod ectoparasitic infections from Merlangius merlangus and Platichthys flesus were examined and related to the annual migrations of young fish into an estuary. Lernaeocera branchialis (L.) was the only parasite common to both fish species; its life-cycle stages infected the branchial chambers of 96·7% flounders (P. flesus) and 40·4% whiting (M. merlangus). Infection in the two fish species exhibited similar seasonal fluctuations and a temporal relationship between the parasite's occurrence on its two hosts was apparent. Whiting were also parasitized by Clavella uncinata (Milller); 26·9 % fish were affected. The copepods' distribution was highly localized with the majority restricted to the long gill rakers of the first gill arch. Infection was related to size of whiting up to 12·5 cm; there was little increase beyond this length. In addition to L. branchialis, flounder was also host to Acanthochondria depressa (T. Scott) and Lepeophtheirus pectoralis (Muller). A. depressa showed a preference for the ocular side of the body with its developing stages attached mainly to the second gill arch and the adults located in the posterior pocket of the branchial chamber. L. pectoralis was associated with the paired fins. Factors which could result in such localized distributions are discussed.

Abstract: A collection of copepods parasitic on fishes taken mainly off the coast of New South Wales, Australia, at depths 274–1 150 m, is described and illustrated. It comprises 23 species, of which only 19 can be identified and described in any detail. Seven species belong to the family Chondracanthidae, one to Caligidae, 10 to Lernaeopodidae and one to Naobranchiidae. Five of these species (Acanthochondria incisa, Chondracanthus genypteri, Ch. neali, Ch. polymixiae and Clavella ovata) have been found in Australian waters for the first time. The remaining comprise two new genera (Rohdea and Cryptova) and 12 new species (Rohdea cryptopoda, Lateracanthus novus, Caligus cresseyorum, Cryptova limbifera, Clavella tumidula, C. deminuta, Anaclavella (?) filifera, Neobrachiella brevibrachiata, N. microdigitata, N. chlorophthalmi, N. mirifica and Naobranchia alta). The exact generic affiliation of A. (?) filifera is impossible, because the male of its only other hitherto known species, A. sillaginoides, has not been found...

Abstract: The composition of the parasite fauna of the flounder, Platichthys flesus, retrieved from two locations in the tidal Thames is described in detail for the first time. The combined parasite species list of the flounders from Lots Road in the upper tideway and West Thurrock in the middle tideway consisted of one protozoan (Glugea stephani), one monogenean (Gyrodactylus sp.), four larval digeneans (Cryptocotyle concava, Timoniella imbutiforme, T. praeterita, and Labratrema minimus), five adult digeneans (Derogenes varicus, Lecithaster gibbosus, Podocotyle sp., Plagioporus varius, and Zoogonoides viviparus), one larval cestode (unidentified tetraphyllidean), one or possibly more larval nematodes (unidentified) plus five adult nematodes (Capillaria sp., Cucullanus heterochrous, C. minutus, Contracaecum sp. and Goezia sp.), two acanthocephalans (Pomphorhynchus laevis and Acanthocephalus anguillae), three copepods (Lepeophtheirus pectoralis, Acanthochondria sp. and Lernaeocera branchialis), and one mollusc (unidentified glochidia). The overall parasite community of flounders from Lots Road and West Thurrock were compared in terms of species richness and diversity. The parasite community in flounders from the former location in the upper tideway was found to be less diverse than that of its counterpart at West Thurrock in the middle estuary. The component community of Lots Road flounders was dominated by the acanthocephalan Pomphorhynchus laevis.