Cycle de développement de l'éphéméroptère Baetis rhodani Pictet dans deux rivières salmonicoles belges: la Rulles et le Samson

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Summary

The life cycle of the mayfly Baetis rhodani Pictet was studied in two salmonicol rivers which are different in temperature and in degree of mineralization of their waters. In the two rivers Baetis rhodani has two generations and the individuals of the spring generation are bigger than those of the summer one. Nevertheless, differences appear between the two environments. Accelerated spring growth of larvae and emergence begins earlier in the more mineralized water. Also the average length and weight are superior to those of the less mineralized river. These differences were compared with the primary production which depends on temperature and mineralization of the water.