河流健康指标和评估

River Health Indicators
Invertebrates as response indicators
Why use invertebrates?
– Ubiquitous (found almost everywhere) • occur in most habitats across a diverse range of aquatic systems – Many species and families • have a broad range of responses to disturbance – Sedentary • effective spatial analyses of pollutants or disturbance effects – Relative longevity • They can be used to assess changes through time
Steps in developing a river health program
What are “indicators of river health”?
• River „health‟ can be assessed using indicators of a river‟s ecological condition in terms of its physical, chemical and biological attributes • These indicators must be efficient, rapid and founded on ecology, and must also
River Health Indicators
Why monitor beyond water quality?
• There are other forms of human disturbance to rivers that we want to detect besides pollution • Water quality is highly variable through time, biological indicators tend to be less so • There are more pollutants than it is possible to measure • Pollutants interact and cause synergistic effects that may be unknown • Biological indicators integrate through time and across multiple stressors
– be responsive to environmental changes – be comparative over different ecological regions, and – report on the whole ecosystem condition
• No shortage of potential indicators
No
yes River Classification Adopt appropriate standard
Can thresholds and targets be established from the data? yes Include in scorecard
No Consider for future programs
River Health Indicators
Invertebrates as response indicators
• Some limitations
– typically used for small or wadeable streams (edge and riffle habitats) rather than large, un-wadeable rivers – taxonomy may be poorly developed for some regions (hard to identify all species) – taxonomic identification and sample processing can be intensive and take a long time depending on the level of identification required – multiple samples or compositing of samples from one site may be required to reduce variation between samples / sample the river community thoroughly
River Health Indicators
Biological indicators show structural and functional responses
• Biotic communities and populations show structural changes in response to disturbance
River Health Indicators
Different kinds of indicators…
• Pressure Indicators (indicators of human disturbance)
– – – – – Measures of hydrological alteration Indicators of channel modification Land-use change indicators Measures of nutrient and sediment inputs Indicators of exotic and/or invasive species‟ introductions
Did the indicator respond as expected?
Land-use assessment to define disturbance gradient No Review indicator
Consider for inclusion in scorecard
yes
Do standards already exist (Chinese or international)
• They also have functional and process responses to disturbance
• Change in condition (e.g. fish body weight to length ratio usually decreases) • Change in food webs (e.g. fish predator to prey ratios usually decreases) • Change in recruitment / reproduction (e.g. number of young fish in the total fish population usually decreases)
– How do you standardise and compare indicators among sites and through time (how do you score river health)? – Does the score make sense?
• Different ways to combine scores for reporting
• Ecosystem Response Indicators
– Indicators of an ecosystem response to environmental change
River Health Indicators
Types of ecosystem response indicators we typically use.....
• Process and biological function indicators
– Primary production, benthic metabolism and nutrient cycling, decomposition, fish body condition, food webs
• Change in diversity (usually decreases) • Change in abundance (sometimes increases) • Loss of certain groups (loss of diversity and/or abundance)
– E.g. sensitive macroinvertebrate taxa like Trichoptera (caddisflies), Ephemeroptera (mayflies) and Plecoptera (stoneflies) = EPT taxa
River Health Indicators and Assessment
Flow chart of the process
Conceptual models Identify suite of potential indicators Field trial Assess indicator sensitivity to disturbance gradient
• First session (Cath Leigh):
– Indicators and benchmarking for scoring and assessing river health
• Second session (Nick Bond):