Terrestrial invertebrates as bioindicators Flashcards
What is a bioindicator?
Taxonomic i.d. versus functional group i.d. -> both can be useful
Indicate environmental change
Monitor particular stressors (detectors versus exploiters; also accumulators)
Indicate overall levels of biodiversity
How to select terrestrial invertebrates as bioindicators?
Several taxa
Separate abundance fluctuation from change of interest
Model change in abundance with variable of interest e.g. in a predictive relationship like a regression
What ecosystem attribute do you want to measure?
Do you know important life-history features of your group (e.g. LH-stage & phenology)
How good is knowledge of distribution, environmental tolerance?
Can you identify them
What do you think is a problem here?
Case study I: Dung beetles as bioindicators
Bioindicators must have strong relationship with environmental characteristic
Robustness of this should be tested
Bioindicators need a degree of specificity to the environment
Two sand forest sites
Two mixed woodland sites
Two disturbed sand forest sites
SYSTEMATIC PITFALL GRID SAMPLING
Baited with elephant dung and sampled every 48hrs
High and significant percentages indicate good indicator species
They selected species with moderate affinity for woodland and not much affinity for sandy habitat as bioindicators
Case study II: Chironomids as indicators of stress
Tested a bioassay using chironomid mouthpart deformities as a measure of environmental stress
Sediments absorb and bind toxins which may be bioavailable
Toxic pollutants may induce mouthpart deformities in chironomids
Advantage: can use at sites where it is not naturally present
Increase in abundance with stress
Can also use deformities as an index of pollution
Case study III: Biodiversity indicators of species richness
Conservation planners need to assess species richness
Complete species inventories are expensive and time consuming
Does the indicator species approach have validity within taxonomic groups?
Glossary of some key terms
Bioindicator> a species or collection of taxonomic groups that can be used to monitor particular stressors (e.g. toxins in the environment), indicate overall levels of biodiversity in an area or indicate some aspect(s) of environmental change
Specificity> indicates that a species is more limited to one particular site, based on the spread of individuals across sites
Fidelity> in a bioindicator context, this indicates the proportion of sites occupied by a species in a particular habitat
Species richness> total number of species (per sample, per site, per habitat etc).
RIVPACS, RICT> a sampling method that uses aquatic invertebrates to give an indication of water quality
