The influence of floods on the life history of dominant mayflies (Ephemeroptera) in a subtropical mountain stream

MOLINERI, C.

STUDIES ON NEOTROPICAL FAUNA AND ENVIRONMENT

TAYLOR & FRANCIS LTD

Año: 2010 vol. 45 p. 149 - 157

0165-0521

The larval life cycles and annual production of two mayfly (Ephemeroptera) species were studied in a subtropical low-order mountain stream. The relationship between precipitation and nymphal density, biomass (B) and secondary production was also investigated. Surber samples were taken weekly during a period of two years. Life spans were estimated from size-class frequency graphs and, independently, from nymphal length and environmental data. Annual production (P) was calculated using the size-frequency method. Thraulodes consortis (Leptophlebiidae) and Leptohyphes eximius  (Leptohyphidae) showed asynchronous and continuous multivoltine life cycles. Mean life spans were 74 days for L. eximius and 124 days for T. consortis. Annual production values ranged from 1.4 to 4.05 g/m2 year in T. consortis, and from 0.28 to 0.93 g/m2 year in L. eximius. Annual P/B ratio ranged from 9 to 15 in T. consortis, and from 15 to 17 in L. eximius. Nymphal density and biomass declined abruptly after heavy storms but recovered quickly. Daily production was much higher in the dry than in the wet season for both species. Thraulodes consortis (Leptophlebiidae) and Leptohyphes eximius  (Leptohyphidae) showed asynchronous and continuous multivoltine life cycles. Mean life spans were 74 days for L. eximius and 124 days for T. consortis. Annual production values ranged from 1.4 to 4.05 g/m2 year in T. consortis, and from 0.28 to 0.93 g/m2 year in L. eximius. Annual P/B ratio ranged from 9 to 15 in T. consortis, and from 15 to 17 in L. eximius. Nymphal density and biomass declined abruptly after heavy storms but recovered quickly. Daily production was much higher in the dry than in the wet season for both species.