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 metric is a value calculated from a
particular set of measurements.
An indicator is 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