Severe dermatitis and branchitis are described in a wild population of empire gudgeon Hypseleotris compressa, an Australian eleotrid, exposed naturally to runoff from acid sulfate soils (ASS) in a drained estuarine embayment in eastern Australia. After at least 2 d exposure to pH < 4, and up to 7 d exposure to pH < 6, approximately 50% of the fish sampled had moderate to severe diffuse epidermal hyperplasia, usually at scale margins, and scattered areas of moderate to severe, focal to locally extensive, subacute, necrotising dermatitis. Saprolegnia spp. had invaded epidermis in some inflamed areas. In gills, there was moderate to severe hyperplasia and necrosis of secondary lamellar epithelium, with fusion of adjacent secondary lamellae. Inorganic monomeric aluminium and calcium concentrations in water at the site during the event were 27.7 and 16.6 mg l -1 , respectively. Large numbers of empire gudgeons at the study site had died after at least 8 d exposure to pH < 4, and up to 13 d exposure to pH < 6. These findings provide clear evidence that acidification of estuarine systems by runoff from ASS has deleterious effects on aquatic biota. Furthermore, study findings suggest a mechanism whereby lesions of epizootic ulcerative syndrome (EUS) may be initiated in estuarine fishes by a combination of sublethal exposure to ASS runoff and Aphanomyces invadans infection, a suggestion consistent with the geographic and temporal distribution of EUS outbreaks in Australian estuaries.KEY WORDS: Dermatitis · Mortality · Branchitis · Fish · Acid sulfate soils · Saprolegniasis · Epizootic ulcerative syndrome · EUS
Resale or republication not permitted without written consent of the publisherDis Aquat Org 63: [247][248][249][250][251][252][253] 2005 posure (Daye & Garside 1980, Freda & McDonald 1988, Playle et al. 1989, Mount et al. 1990, Witters et al. 1990, Norrgren et al. 1991, Poleo et al. 1991, Galle & Montoroi 1993. Gill lesions, typically including lamellar epithelial hyperplasia and fusion of secondary lamellae, are common in fish exposed naturally or experimentally to acidified water (Daye & Garside 1976, Linnenbach et al. 1987, Dietrich & Schlatter 1989, Norrgren et al. 1991. Mild skin lesions, including increased secretion of mucus, cutaneous goblet cell hypertrophy and/or hyperplasia, as well as more severe skin lesions, including epidermal necrosis and sloughing, have also been described in fish exposed experimentally to acidified water (Daye & Garside 1976, Tandjung et al. 1982, Segner et al. 1988, Ingersoll et al. 1990b, Iger & Wendelaar Bonga 1994. We have found no reports of skin lesions in naturally exposed fish.In this paper we describe severe dermatitis with opportunist mycotic involvement, branchitis and mortality in a wild population of empire gudgeon Hypseleotris compressa, an Australian eleotrid, exposed naturally to acidified runoff from ASS.
MATERIALS AND METHODSAs part of a study examining possible relationships between ASS runoff and deleterious effects on aquatic biota, water quality ...