Bioassessment and biomonitoring: some general principles
What’s the difference? Bioassessment: - the use of living organisms to assess aspects of the integrity (condition, ‘health’) of the environments in which they live OR - the process of determining if human activity has altered the biological properties of an ecosystem
Biomonitoring: the use of living organisms to track conditions in the environments in which they live OR the systematic use of biological responses to evaluate environmental changes [within a quality-control programme]
A metricis a value calculated from a particular set of measurements. An indicatoris a feature (biological, physical, chemical, a metric, an index) that reflects specific condition or change in condition. An index is a numerical indicator derived from a series of metrics.
Indices can be based on metrics derived from the biota e.g. SASS (inverts); VEGRAI (riparian veg.) or physical features e.g hydrological, habitat indices or mixed features e.g. WetEcoservices: derived from socio-economic & biotic indices
Bioassessment uses components of the biota to reflect aspects of e.g. - water chemistry - hydrology (e.g. water level) - availability of nutrients - ecosystem integrity (‘health’) - suitability for particular purposes (i.e. ‘quality’) etc. e.g. the Saprobien Index: organic pollution
Why bioassessment? While chemical and physical analyses are - reliable (accurate, repeatable) - provide ‘instant’ snapshots’ They are - limited to the period of sample collection - limited to the constituents measured - expensive (if comprehensively done) - limited by sensitivity of the methods used: low concentrations cannot be detected.
Living organisms - provide a longer-term view - are continuous monitors: they integrate effects of time and multiple pollutants - can be cheap and easy to assess - can be used for different purposes - account for synergistic (magnifying) and antagonistic (reducing) effects (e.g. pH)
Where does ecotoxicology fit in? The study of the effects of toxic substances on [aquatic] organisms usually laboratory-based experiments link between WQ and its effects on the biota: e.g. used for deriving guidelines includes field studies: bioaccumulation / biomagnification “active biomonitoring” use of biomarkers
Which organisms to use in bioassessment? Protozoa /diatoms – identification specialised Algae / periphyton Macroinvertebrates Fish Macrophytes Birds
First ask, WHAT DO WE WANT THE BIOTA TO TELL US?? i.e. what are we monitoring FOR?
e.g. it can provide a measure of change We can monitor specific features, usually at fixed points: e.g. edges between veg. types water level degree of sedimentation fixed-point photography geomorphology of channels density of aliens aspects of ground water
Individual species as ‘indicator species’ e.g. halophytes & halophobes tolerators of low pH rapid responders to changes in nutrient levels those whose eggs must desiccate before hatching ruderal species …
Can use assemblages: e.g. diatoms (good for aspects of water chemistry) odonates (IBI?) molluscs (IBI?) macrophytes (hydroperiod / water level) macro-invertebrates (generalized impairment of water quality)
What criteria are important when selecting techniques / indicators? - rapidity (& therefore cost) - narrowness of tolerance ranges - common-ness (or even rarity) - ease of identification - life cycle of the right length
What methods of analysis? What taxonomic level of identification? What numerical methods – simple arithmetic (e.g. SASS)? multivariate analyses (e.g. AusRivas, Rivpacs): predictive modelling? Validation of proposed indices? What level of confidence is necessary?
What can biomonitoring NOT do?? It cannot replace phys & chem. data (it complements it) It does not explain the cause of the problem, merely indicates that there is one It seldom predicts outcomes (but indicates trajectory of change).
THE NATIONAL WETLAND RESEARCH PROGRAMME PHASE II: WETLAND HEALTH AND INTEGRITY
Development of the WHI research programme: Strategic overview of research needs in wetlands Malan & and Day (2005) Strategic overview of the research needs for wetland health and integrity. WRC Report no. KV 171/05. Malan, Day & Marr (2005) Assessment of wetland ecological health and socio-economic importance: an annotated bibliography. WRC Report no. KV 172/05
Aims of the WHI research programme To develop tools for assessing - ecological condition - aspects of the biophysical environment (e.g. water quality, hydroperiod) - socio-economic importance - loss of wetland function through degradation …
THE INDIVIDUAL PROJECTS DIATOM INDEX Development of an index based on diatoms - commonly used for aspects of water chemistry MACROPHYTE INDEX Development of an index of biotic integrity / ecosystem condition based on macrophytes - consolidation of plant species lists: individual species as indicators of specific conditions (e.g. high salinity or low pH)
INVERTEBRATE INDEX To investigate the feasibility of developing an index of wetland health using invertebrates - PhD project DRY CONDITION INDEX - identification of non-perennial wetlands - assessment of their condition / integrity in the dry state Use of macrophytes? invertebrates? diatoms?
TESTING OF EXISTING TOOLS: critique/gap analysis - WET-EcoServices (index of ‘functionality’): rapid evaluation of wetland goods & services - WET-Health (a type of IBI) - Ecological Importance and Sensitivity (to be used by DWAF)
DEPENDENCY METRIC Development of a metric of socio-economic dependency of communities on a wetland SUSTAINABILITY METRICS: effect of human use on - ecosystem functionality - sustainability use of a wetland
LOSS-OF-FUNCTION METRIC Relationship between function and extent of degradation LANDSCAPE-LEVEL IMPACTS The cumulative impact of wetland loss at the landscape level