Responses of Macroinvertebrate Assemblages to Flow Variations in the
Qinghai-Tibet Plateau: Establishment and Application of a Multi-metric
Habitat Suitability Model
Abstract
Anthropogenic impacts and climate change modify instream flow, altering
ecosystem services and impacting on aquatic ecosystems. Alpine rivers
and streams on the Qinghai-Tibet Plateau (QTP), are especially
vulnerable to disturbance due to a limited taxonomic complexity. The
effects of variations in flow have been studied using specific taxa,
however, the flow-biota relationships of assemblages are poorly
understood. A multi-metric habitat suitability model (MM-HSM) was
developed, using biological integrity measures of macroinvertebrate
assemblages to substitute for habitat suitability indices (HSI) derived
from individual taxa. The MM-HSM was trained using macroinvertebrate
data from three representative alpine rivers (the Yarlung Tsangpo, the
Nujiang, and the Bai Rivers) on the QTP, and was verified using data
from the Lanmucuo River. The model produced reliable predictions using
the training dataset (R2 = 0.587) and the verification dataset (R2 =
0.489), and was robust to inter-basin differences and changes in dataset
size. By coupling the MM-HSM with hydrodynamic simulations, the
relationship between weighted usable area (WUA) and flow variations
(0.11–1.99 m3/s) for macroinvertebrates was established, and a unimodal
response pattern (optimal flow Q = 1.21 m3/s) was observed for
macroinvertebrate assemblages from the Lanmucuo River. This was in
contrast to the skewed unimodal or monotonically increasing
relationships observed for individual indicator taxa, supporting our
hypothesis that biological integrity varies with changing flow and
conforms to the intermediate disturbance hypothesis. The MM-HSM provides
a novel framework to quantify species-environment relationships, which
may be used for integrated river basin management.