The Behaviour of Gasterosteus Aculeatus L. in the Zone of Action of Warm Waste Waters

Abstract

[The behaviour of Gasterosteus aculeatus L. was studied in the escape canal of an electric power station, which uses the water of a sea bay for cooling. In spring, warm waters attract G. aculatus into the escape canal, where males construct nests and spawning occurs. The male: female ratio in catches is usually 1 :8. When the temperature in the canal was raised to 28-30°C, a part of the females died, the percentage of the males increased to 47%. Among the captured females, the majority had attained the IIIrd stage of maturity, since the females with more mature eggs had died. Of great interest is the fact that in the stomachs of most males eggs of their own species were present, at various developmental stages. Since G. aculeatus males construct a nest which is carefully protected against enemies, there is ground to believe that the rise in temperature to over 28°C in the escape canal resulted in disruption of parental behaviour. Incubation of the eggs taken from a G. aculeatus nest constructed in the canal, revealed that the eggs could develop without any visible anomalies at rather high temperatures (24-26°C), and even sustain a short-term increase of temperature to 37°C at the stage of the segmentation of the trunk mesoderm. That gives evidence that the increase of temperature of waste waters can be sustained by the eggs, but eventually it causes their death due to the disturbance of the male's parental behaviour. The male either eats the eggs laid in his own nest, or he gives up the nest, and the eggs are eaten by other fish as a result., The behaviour of Gasterosteus aculeatus L. was studied in the escape canal of an electric power station, which uses the water of a sea bay for cooling. In spring, warm waters attract G. aculatus into the escape canal, where males construct nests and spawning occurs. The male: female ratio in catches is usually 1 :8. When the temperature in the canal was raised to 28-30°C, a part of the females died, the percentage of the males increased to 47%. Among the captured females, the majority had attained the IIIrd stage of maturity, since the females with more mature eggs had died. Of great interest is the fact that in the stomachs of most males eggs of their own species were present, at various developmental stages. Since G. aculeatus males construct a nest which is carefully protected against enemies, there is ground to believe that the rise in temperature to over 28°C in the escape canal resulted in disruption of parental behaviour. Incubation of the eggs taken from a G. aculeatus nest constructed in the canal, revealed that the eggs could develop without any visible anomalies at rather high temperatures (24-26°C), and even sustain a short-term increase of temperature to 37°C at the stage of the segmentation of the trunk mesoderm. That gives evidence that the increase of temperature of waste waters can be sustained by the eggs, but eventually it causes their death due to the disturbance of the male's parental behaviour. The male either eats the eggs laid in his own nest, or he gives up the nest, and the eggs are eaten by other fish as a result.]