Bruno, M.C.

Carolli, M.

Maiolini, B.

Siviglia, A.

Bruno, Maria Cristina

Carolli, Mauro

Maiolini, Bruno

Archivio istituzionale della ricerca - Fondazione Edmund Mach

 Multiple Responses of Benthic Invertebrates to Hydropeaking WavesMaria Cristina Bruno, Fondazione E. Mach IASMA Research and Innovation Centre, Sustainable Agro-ecosystems andBioresources DepartmentAnnunziato Siviglia, University of Trento, Department of Civil and Environmental EngineeringMauro Carolli, Fondazione E. Mach IASMA Research and Innovation Centre, Sustainable Agro-ecosystems and BioresourcesDepartmentBruno Maiolini, Fondazione E. Mach IASMA Research and Innovation Centre, Sustainable Agro-ecosystems and BioresourcesDepartmentAbstract Sudden instream releases of hypolimnetic water from hydropower plants with high elevation storage reservoirs causeabrupt increases in discharge (i.e., hydropeaking) and can cause abrupt variations in temperature (i.e., thermopeaking),typically on a daily basis. The propagation of the discharge and thermal waves are asynchronous, causing the benthiccommunity to undergo two distinct but consecutive impacts. Because in experiments conducted in natural conditions it isdifficult to disentangle the multiple effects of hydropeaking and thermopeaking, our research group started a set ofexperiments on the effects of hydropeaking and thermopeaking on benthic macroinvertebrates in an experimental structureof five steel channels directly fed by the Fersina Stream (left tributary to the Adige River). One hydropeaking event wassimulated in 2008 with two increases of flow: abrupt and gradual. Invertebrates responded to the sudden increases withstronger intensity than to the gradual increase, with an increase of active (catastrophic) drift. Two cold and two warmthermopeaking events were simulated in 2008-2009. Macroinvertebrates responded to the disturbance by increasing in drift,with temporal drift density trend inversely related to changes in water temperature. Although the achieved changes intemperature were within the tolerability range for benthic invertebrates, their drift increased and was probably behavioral,given the immediate responses of invertebrates which seek habitat patches which are within their temperature toleranceand/or preference levels. Catastrophic and behavioural drift can occur as distinct events in hydropeaking-impacted streams,thus we analysed the effects of a hydropeaking wave followed by a thermopeaking wave in the same flume system. Weobserved that the slight but abrupt increase in discharge caused an increase in drift but the abrupt decrease in temperaturecaused a stronger response. The long-term effects of thermopeaking are mixed and synergical with those due tohydropeaking and, on the long-term, may alter the longitudinal distribution of benthic communities.Powered by TCPDF (www.tcpdf.org)page 1 / 1

Multiple responses of benthic invertebrates to hydropeaking waves

https://openpub.fmach.it/bitstream/10449/21606/1/14752.pdf

Multiple responses of benthic invertebrates to hydropeaking waves

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Archivio istituzionale della ricerca - Fondazione Edmund Mach