Seasonal dynamics of Callibaetis willineri (Ephemeroptera, Baetidae) associated with Eichhornia azurea (Pontedericeae) in Guaraná Lake of the Upper Paraná River, Brazil
文摘
Nymphs of the Callibaetis willineri Navás, 1932 colonize Eichhornia azurea in Guaraná Lake, a várzea (floodplain) lake of the Upper Paraná River. The plants were sampled monthly from October 1997 to October 1998. Higher abundances of C. willineri coincided with months of higher dissolved oxygen concentrations in the water, suggesting that the nymphs were sensitive to variations in dissolved oxygen. The presence of different size classes and the predominance of small specimens suggest that this species has asynchronous development.