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Diseases of Aquatic Organisms

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DAO 64:223-228 (2005)  -  doi:10.3354/dao064223

Physiological responses to acute temperature increase in European eels Anguilla anguilla infected with Anguillicola crassus

Matthew J. Gollock1,2,*, Clive R. Kennedy1, J. Anne Brown1

1School of Biological and Chemical Sciences, Hatherly Laboratories, University of Exeter, Prince of Wales Road, Exeter, Devon EX4 4PS, UK
2Present address: Ocean Sciences Centre, Memorial University of Newfoundland, St John’s, Newfoundland A1C 5S7, Canada

ABSTRACT: The swimbladder parasite, Anguillicola crassus has infected, and spread rapidly, through European eel Anguilla anguilla (L.) populations over the past 20 to 25 yr. Our aim in the present studies was to elucidate whether the presence of A. crassus in these eels alters their rapid physiological responses to an acute temperature increase, compared to the response of uninfected fish. Both infected and uninfected fish showed significant increases in plasma cortisol after 2 h at a raised environmental temperature with increased plasma glucose after 6 h. However, infected eels exhibited a slight lag in glucose mobilisation, which may be due to the metabolic cost of harbouring a sanguiverous parasite. Both infected and uninfected fish showed a significant increase in haematocrit after 6 h of temperature elevation, but only uninfected fish exhibited a significant increase in haemoglobin at this point. However, there were no significant changes in mean erythrocyte haemoglobin concentration in either group. Our results suggest that acute temperature increase alone is unlikely to cause significant mortality of A. crassus-infected European eels; however, the effects of chronic increases in temperature in combination with other factors such as toxicants and hypoxia requires examination.

KEY WORDS: Anguillicola crassus · Anguilla anguilla · Temperature · Stress · Cortisol · Glucos

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