Responses of multiple structural and functional indicators along three contrasting disturbance gradients

Ecosystem functioning and community structure are recognized as key components of ecosystem integrity, but comprehensive, standardized studies the responses both structural functional indicators to different types anthropogenic pressures remain rare. Consequently, we lack an empirical basis for (i) identifying when monitoring alone misses important changes in functioning, (ii) recommending sets metrics best suited detecting ecological change driven by pressures, (iii) understanding cumulative effects multiple, co-occurring stressors on function. We investigated variation stream ecosystems along three gradients (10–16 independent sites each) increasing impact arising from agriculture, forestry river regulation hydropower, respectively. For each stream, quantified abiotic environment, composition four organism groups basal processes underpinning carbon nutrient cycling streams. assessed responsiveness multiple biodiversity, based variance explained effect size metrics. Along a gradient agricultural impact, diatoms fish were most responsive overall, significant was detected at least one aspect composition, abundance and/or biodiversity every group . In contrast, our did not vary significantly gradient, possibly due contrasting, antagonistic concentrations turbidity process rates. The exception detritivore-mediated litter decomposition which increased up moderate levels nutrient. Impacts marked diatoms, increasingly frequent hydropeaking seasonal regulation. Among indicators, algal biomass accrual declined with hydropeaking. Few or varied forest management, macroinvertebrate diversity fungal accrual. Together, these findings highlight challenges making inferences about impacts disturbances level data alone, pinpoint need identify optimal associated human activities.