Application of Synchronous Evaluation-Diagnosis Model with Quantitative Stressor-Response Analysis (SED-QSR) to Urban Lake Ecological Status: A Proposed Multiple-Level System

Ecological integrity assessment and degradation diagnosis
are used
globally to evaluate the health of water bodies and pinpoint critical
stressors. However, current studies mainly focus on separate evaluation
or diagnosis, leading to an inadequate exploration of the relationship
between stressors and responses. Here, based on multiple data sets
in an urban lake system, a synchronous evaluation-diagnosis model
with quantitative stressor-response analysis was advanced, aiming
to improve the accuracy of evaluation and diagnosis. The weights for
key physicochemical stressors were quantitatively determined in the
sequence of NDAVIadj > CODMn > TP >
NH4+–N by the combination of generalized
additive
model and structural equation modeling, clarifying the most significant
effects of aquatic vegetation on the degradation of fish assemblages.
Then, sensitive biological metrics were screened by considering the
distinct contributions of four key stressors to alleviate the possible
deviation caused by common methods. Finally, ecological integrity
was evaluated by summing the key physicochemical stressors and sensitive
biological metrics according to the model-deduced weights instead
of empirical weights. Our system’s diagnosis and evaluation
results achieved an accuracy of over 80% when predicting anthropogenic
stress and biological status, which highlights the great potential
of our multiple-level system for ecosystem management.