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New Zealand Journal of Marine and Freshwater Research abstracts
Recovery of benthic macroinvertebrate and epilithic communities following a large flood, in an unstable, braided, New Zealand river
GARRY J. SCRIMGEOUR* ROBERT J. DAVIDSON JACQUELINE M. DAVIDSON
Department of Zoology University of Canterbury Private Bag, Christchurch New Zealand
Abstract Benthic macroinvertebrates and small stones were collected from a riffle in the Ashley River, North Canterbury, New Zealand, on 12 occasions within a 132-day period following a particularly large flood in 1986. Despite the occurrence of smaller floods during this period, benthic macroinvertebrate communities and stone surface organic layers recovered rapidly. Mean concentration of stone surface organic carbon increased from 0.23 g/ni2 to 1.01 g/m2 stone surface in the first 23 days after the flood and chlorophyll a concentration increased from 0.13 mg/m2 (day 3) to 9.2 mg/m2 by day 132. Minor floods during the recover,' period had little effect on organic layer biomass. Mean faunal density increased from 230/m2 to 7920/m2 during this time and taxon richness; from 7 to 21 per 5 benthic samples. Immediately after the flood and throughout the study period the fauna was dominated by larvae of Deleatidium (Ephemeroptera: Leptophlebiidae), Hydora (Coleoptera: Elmidae), and Chironomidae. Re-establishment of Deleatidium populations in previously denuded brands was effected by ovi-position, egg-hatching, and larval immigration. Minor braids are likely to represent important epicentres from which recolonisation proceeds.Keywords Deleatidium sp.; Leptophlebiidae; benthic macroinvertebrates; recovery; floods; disturbance; epilithon; stream; organic layers
New Zealand Journal of Marine and Freshwater Research, 1988, Vol. 22 : 337-344 Crown copyright 1988Received 15 August 1987; accepted 16 November 1987
PDF file of entire paper: medium quality (623K); (scanned from paper original: notes about this process)
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