Consideration of Multitrophic Biodiversity and Ecosystem Functions Improves Indices on River Ecological Status

Abstract

Biological quality elements have been developed worldwide to assess whether a water body is in a good status or not. However, current studies mainly focus on a single taxonomic group or a small set of species, often limited by methods of morphological identification, and lack further aspects of biodiversity (e.g., across taxa and multiple attributes) and ecosystem functions. Here, we advance a framework for assessing the river’s ecological status based on complete biodiversity data measured by environmental DNA (eDNA) metabarcoding and measurements of ecosystem functions in addition to physicochemical elements across a large riverine system in China. We identified 40 indicators of biodiversity and ecosystem functions, covering five taxonomic groups from bacteria to invertebrates, and associated with multiple attributes of biodiversity and ecosystem functions. Our data show that human impact on ecosystems could be accurately predicted by these eDNA-based indicators and ecosystem functions, using cross-validation with a known stressor gradient. Moreover, indices based on these indicators of biodiversity and ecosystem functions not only distinguish the physicochemical characteristics of the sites but also improve the assessment accuracy of 20–30% for the river’s ecological status. Overall, by incorporating eDNA-based biodiversity with physicochemical and ecosystem functional elements, the multidimensional perspectives of ecosystem states provide additional information to protect and maintain a good ecological status of rivers.

Destabilizing Effects of Environmental Stressors on Aquatic Communities and Interaction Networks across a Major River Basin

“…40 000 km 2 . This region was chosen because it has a clear stress gradient on the spatial scale, such as less intensity of human land use and better ecological status in the upstream than that of the middle and downstream. − A total of 20 sites were selected across the Shaying River network, representatively covering different branches and tributaries across the whole catchment. The sites covered individual tributaries as well as the downstream reaches of their intersection.…”

“…Field samples were collected 4 times across 3 years (from 2018 to 2020), namely, in April 2018, October 2018, October 2019, and December 2020, and multiple organismal groups were analyzed, including bacteria, algae, fungi, protozoa, and invertebrates. The sampling strategy of eDNA samples refers to our published studies in the same region. , Briefly, three 1 L samples of surface water were collected per site using sterile bottles (Thermo Fisher, U.S.A.). We set up six field replicates (or subsamples) for each site by filtering 300–500 mL volume of water using a Millipore 0.45 μm hydrophilic nylon membrane (Merck Millipore, U.S.A.).…”

“…The 1 L surface water was diluted with 2% HNO 3 and filtered through a 2.5 μm membrane filter (Whatman, U.K.) for measuring the concentration of different heavy metals using inductively coupled plasma mass spectrometry (Thermo Fisher, U.S.A.). These 10 pollutants were selected because previous studies have suggested that nitrogen, phosphorus, and various heavy metal loads pose potential high ecological risks in the Shaying River. ,, …”

Environmental DNA Biomonitoring Reveals the Interactive Effects of Dams and Nutrient Enrichment on Aquatic Multitrophic Communities

“…The datasets containing the Illumina raw sequence data were submitted to the NCBI Sequence Read Archive under accession project number PRJNA859522. We used the following three steps to filter the OTU tables to identify the reliability of the datasets: 33,47 (1) OTUs with a detection frequency of <50% in all subsamples at any single site were discarded to eliminate false positive OTU detection; (2) all subsamples at the same sampling site were merged by additive averaging to obtain the OTU dataset of the sampling site; (3) any OTU with relative abundances <0.001% and detection frequency <10% across all sites were discarded and then the final OTUs tables were obtained (i.e., OTUs × sites). After the above three screening steps, no sequences were retained in the blank controls.…”

Water Quality and Microbial Community in the Context of Ecological Restoration: A Case Study of the Yongding River, Beijing, China

“…Effective river restoration requires a complete understanding of the whole river ecological system, including the physical, chemical, and biological parameters [ 11 , 12 ]. Water quality may be changed by habitat restoration, and microbes are closely associated with variations in specific environmental factors, such as chemical oxygen demand, total nitrogen, and nitrate nitrogen [ 13 , 14 ].…”