Similarities and differences between the massive eel (Anguilla anguilla L) devastations that occurred in Lake Balaton in 1991 and 1995

• Published in: Ecotoxicology and Environmental Safety
• Main Authors: Bálint Tamás, Ferenczy Judith, Kátai Ferenc, Kiss István, Kráczer László, Kufcsák Oszkár, Láng Gabriella, Polyhos Csaba, Szabó István, Szegletes Tivadar, Nemcsók János
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1997
• Subjects: Brama; Western Basin; Anguilla anguilla; Larus canus; ulv
• Online Access: http://publicatio.bibl.u-szeged.hu/12861/; http://publicatio.bibl.u-szeged.hu/12861/1/2451756.pdf; https://doi.org/10.1006/eesa.1996.1509

In the past few years, two massive eel (Anguilla anguilla L.) devastations occurred in Lake Balaton, Hungary. In 1991, 300 tons of eel perished in the western basin of the lake, while in the summer of 1995 30 tons of eel died in the eastern part of the lake. Investigations carried out to find the causes of these ecocatastrophes included measurements of certain biochemical parameters: the blood sugar level, and the acetylcholinesterase (AChE, EC 3.1.1.7), lactate dehydrogenase (LDH, EC 1.1.2.3), glutamic-oxaloacetic transaminase (GOT, EC 2.6.1.1), and glutamic-pyruvic transaminase (GPT, EC 2.6.1.2) activities in the blood serum of the collected eels. In both 1991 and 1995, deltamethrin (DM), the active ingredient of the insecticide K-OTHRIN 1 ULV used against mosquitoes, was detected in the eels; in 1995 it was demonstrated in several other animal species, i.e., bream (Abramis brama L.), pike perch (Stizostedion lucioperca L.), and the common gull (Larus canus), and in sediment samples from the lake. Additionally, laboratory experiments were carried out to study the effects of DM on eels. In 1991, eels were collected from the western (the site of the devastation) and eastern basins of the lake. The eels from the eastern basin were used as controls. At that time, the AChE activity in the blood serum of the eels from the western basin was significantly inhibited compared to that in animals from the eastern basin (P < 0.05, Student t test). Eels from the western part of the lake had GOT and GPT levels 20 and 100 %, respectively, higher than those of eels from the eastern part of the lake. The blood glucose level was much higher in the eels from the affected area of the lake as compared to those from the eastern part. The brain and liver of the eels contained DM residues at 20 mu g/kg wet tissue (Gonczy, 1992). Gonczy suspected that one of the causes of the massive eel loss in 1991 was the presence of DM in the fish. In 1995, when the eel devastation occurred in the eastern basin, moribund and surviving eels were ...