Histopathology of parasitic infections in greater pipefish, Syngnathus acus L., from an estuary in the UK.
A survey of parasitic diseases in greater pipefish Syngnathus acus from the Mersey estuary in Northern England was conducted in May 2000. A number of different parasites and prokaryotic infections were recorded, including epitheliocystis (23%) and Trichodina sp. in the gills (13%), myxosporeans Kudoa cf. quadratum in the skeletal muscle (3%), Myxidium cf. incurvatum in the gall bladder (33%), the larval nematode Anisakis simplex in the viscera (40%) and metacercaria of the digenean Cryptocotyle lingua in the musculature (17%). In addition, an unidentified digenean was present in the stomach of one fish and cestode plerocercoids were found in the intestines of two fishes. Pathological responses, similar to those reported for other species of fish, were generally minor and included fibrous encapsulation of digeneans and mild epithelial hyperplasia associated with the presence of trichodinids. Epithelial hyperplasia and cellular necrosis were consistent findings and in some cases there was atrophy and sloughing of the epithelial cells. Although greater pipefish have no commercial value and their ecological role as prey items is unknown, an understanding and recognition of the parasite fauna of this and other non-commercial species is important in order to determine their role in disease transmission to commercial stocks, to understand their ecological interactions and to aid in any future captive breeding programmes.