Life history and production of the stream-dwelling mayfly Habrophlebia vibrans Needham (Ephemeroptera; Leptophlebiidae)

Publisher Website
Google Scholar
Abstract
Habrophlebia vibrans in Québec has a 2-year cycle, a feature unexpected in a small mayfly and unreported in Leptophlebiidae. Emergence (875/m2) occurred in June and was synchronous. Ovipositing females concentrated upstream (239 ± 94.7 eggs/female). Eggs hatched within 3 weeks. In summer, nymphs reached densities of 27 500/m2 and a size of 1.65 mm. During the next 18 months, densities decreased (4000–9500/m2). After a year, nymphs were 2.1 mm long and reached 3 mm at the end of their second summer. The final size (5.0 mm) was attained in the last weeks before emergence, and mean densities then were 648/m2. Nymphs lived on gravel where they preferred larger particles and scanty detritus. Drift occurred in small nymphs during August of their 1st year, in larger nymphs during spring runoff, and in mature nymphs at emergence. This resulted in a concentration of emergence in the lower reaches. Annual production was 710–829 mg/m2 and the production to biomass ratio was 2.5–3.2. About three-quarters of the production was due to the 2nd-year cohort, and one-half was accumulated during the last 2 months. No constant relation was found between production and drift and between production and emergence.
Keywords