Impact of oxygen deficiency on the disease status of common dab Limanda limanda

Abstract

ABSTRACT-An epidemiological survey of the fish diseases lymphocystis, epidermal papilloma and skin ulcers in common d a b Limanda limanda L. was conducted in the southern Kattegat each year in May from 1984 to 1993. During the period of investigation, severe oxygen depletion occurred in late summer 1986 and 1988. After the oxygen deficiency in 1986. the occurrence of lymphocystis and epidermal papilloma increased and peaked in 1989 with prevalences of 14 7 and 3.3%, respectively. The prevalence of skin ulcers never exceeded 0.6 %. The relative nsk of contracting lymphocystis increased significantly from 1987 to 1991 compared with 1984 to 1986, the p e r~o d prior to the severe oxygen depletion. A significant increase in the relative risk of contracting epidermal papilloma was observed from 1987 to 1990. Females were 3 times more likely to contract this disease than males. The relative risk of skin ulcers did not change significantly during the investigation period. The prevalence of lymphocystis and epidermal papilloma was negatively correlated with the minimum oxygen levels measured in August and September the previous year; this negative correlation was significant ( p c 0.05) for lymphocystis in September, while not for epidermal papilloma ( p < 0.1). The prevalence of lymphocystis and epidermal papilloma was significantly correlated ( p < 0.01). No significant correlation was observed between stock density (expressed as catch per unit effort) a n d the diseases in question. It is probably the stress caused by the oxygen deficiency -especially the sublethal levels -that triggered the outbreak of the 2 viral diseases lymphocystis and epidermal papilloma.

Epidemiology of lymphocystis, epidermal papilloma and skin ulcers in common dab Limanda limanda along the west coast of Denmark

“…The highest prevalences for lymphocystis and epidermal papilloma were observed in Area 1 (German Bight) and in Area 2 (off the west coast of Denmark) and for skin ulcers in Area 4 (Skagerrak). Similar temporal parallelisms between the diseases lymphocystis and epidermal papilloma have been described before from the German Eight and the Dogger Bank (Dethlefsen 1990) and from the Kattegat (Mellergaard & Nielsen 1995), where statistically significant correlation was found between the 2 diseases. In the present study, these diseases were also found positively correlated in the Areas 1, 2 and 3 but this correlation was not statistically significant.…”

“…Dethlefsen (1990) found that low oxygen levels may be one of the stress factors contributing to the outbreak of lyrnphocystis and epidermal papilloma in the German Bight. It has not been possible to establish significant correlations between lymphocystis and epidermal papilloma and oxygen deficiency in the present material as were demonstrated for the Kattegat (Mellergaard & Nielsen 1995), probably due to the lack of baseline prevalence data for the areas (i.e. before the oxygen deficiency occurred).…”

“…It is likely that oxygen deficiency may be one of the provoking factors for fish diseases in these areas. The hypothesis that oxygen depletion might be involved as a stress factor in the outbreak of lymphocystis and epidermal papilloma in the eastern North Sea was put forward by Mellergaard & Nielsen (1987), whose observations confirmed that in the Kattegat oxygen deficiency was a n important factor in provoking the outbreak of these diseases (Mellergaard & Nielsen 1995). Dethlefsen (1990) found that low oxygen levels may be one of the stress factors contributing to the outbreak of lyrnphocystis and epidermal papilloma in the German Bight.…”

“…Some long-term investigations including ones examining the prevalence and the temporal and spatial trends of fish diseases over wider sea areas have been reported by Dethlefsen et al (1987) and Dethlefsen (1990), who examined diseases in common dab Limanda limanda in most of the North Sea, by Banning (1987), who conducted disease studies in common dab, plaice Pleuronectes platessa and cod Gadus morhua in the south-eastern North Sea, and by Mellergaard & Nielsen (1990, 1995, who carried out disease studies in common dab in Danish coastal zones.…”

“…The first considerations and results of this work on the monitoring of biological effects of marine pollution were summarized by McIntyre & Pearce (1980). During the late 1970s and early 1980s, studies on diseases in wild fish stocks were carried out in many countries, especially those bordering the North Sea and in the USA (Christensen 1980, Dethlefsen 1980, Moller 1981, Despres-Patanjo et al 1982, Deth-Q Inter-Research 1997 Resale of full article not permitted lefsen & Watermann 1982, Mellergaard & Nielsen 1984, 1985, 1995, Vethaak 1991, 1992, 1993, Lindesjoo & Thulin 1994. However.…”