Acanthocephalan parasites collected from Austrian fishes: molecular barcoding and pathological observations

Acanthocephalan parasites were collected from the intestinal tracts of 137 predominantly wild fish (1 barbel Barbus barbus, 3 European chub Squalius cephalus, 13 rainbow trout Oncorhynchus mykiss and 120 brown trout Salmo trutta) from 12 localities. The condition factor, intensity of acanthocephalan infection and pathological lesions, if applicable, were documented. Routine bacteriology and virology were performed, and the brown trout were additionally tested for the presence of the myxozoan parasite Tetracapsolioides bryosalmonae by PCR. In total, 113 acanthocephalans were barcoded by sequencing a section of the mitochondrial cytochrome oxidase subunit I (COI) gene. Barcoding of the acanthocephalan tissues resulted in 77 sequences, of which 56 were assigned to Echinorhynchus truttae (3 genotypes), 11 to Pomphorhynchus tereti-collis (9 genotypes), 9 to Acanthocephalus sp. (5 genotypes) and 1 to Neoechinorhynchida. Most of these genotypes were detected for the first time. Statistically, the acanthocephalan infection did not have an impact on the condition factor of the brown trout. Infection with P. tereticollis caused more severe pathological changes in the digestive tract than E. truttae. The present study provides new data regarding the distribution of acanthocephalan species in Austria and their impact on individual fish. In addition, new barcoding data from acanthocephalan parasites are presented, and the occurrence of P. tereticollis in European chub in Austria and in brown and rainbow trout in general was confirmed for the first time.