biotic integrity ppt
TRANSCRIPT
INDEX OF BIOTIC INTEGRITY
Presentation by Livi Wilson and Jitendra KumarCOF Mangalore
IBI
A scientific tool used to identify and classify water pollution problems.
An IBI associates anthropogenic influences on a water body with biological activity in the water body, and is formulated using data developed from biosurveys
The IBI concept was formulated by Dr. James Karr in 1981
HISTORY
Water quality act ( 1972) stimulated many efforts to monitor the quality of water resource systems
It resulted in development of thresholds & criteria levels for specific contaminants ,often based on acute toxicity tests
Drawbacks
They have not taken into account naturally occurring geographic variations of contaminants (eg:asbestos,iron,zinc)
Considered the synergistic effects of numerous contaminants
Not considered sub lethal effects of most contaminants(eg:reproduction,growth)
Cont…
Chemical monitoring misses many of the man-induced perturbations (eg:flow alterations,habitat degradation,heated effluents)
In short ,criteria that emphasize physical & chemical attributes of water are unsuccessful for measuring biotic integrity
Pollution
Clean Water Act of 1977 defines pollution as
“the manmade or man-induced alteration of the chemical,physical,biological & radiological integrity of water
Biological integrity
“the capability of supporting &
maintaining a balanced,integrated,adaptive community of organisms having a species composition,diversity ,& functional organization comparable to that of the natural habitat of the region”(Frey 1977)
Why monitor fish???
Life history information is extensive for most fish species
Fish communities generally include a range of species that represent a variety of trophic levels
Their position at the top of the aquatic food web in relation to diatoms & invertebrates also help to provide an integrative view of the watershed environment
Cont..
Fishes are relatively easy to identify. Technicians require relatively little training.
Both acute toxicity (missing taxa) & stress effects (depressed growth & reproductive success) can be evaluated
Fishes are typically present ,even in the smallest streams & in all but the most polluted waters
Biotic integrity classesclass Attributes Excellent Comparable to the best situations without influence of man,
with most intolerant forms, full array of age& sex classes; balanced trophic structure
Good Species richness somewhat below expectation, loss of most intolerant forms, trophic structure shows some signs of stress
Fair Signs of additional deterioration include fewer intolerant forms, more skewed trophic structure
Poor Dominated by omnivores, pollution –tolerant forms,& habitat generalists, growth rate & condition factors commonly depressed ;hybrids & diseased fish often present
Very poor Few fish present, mostly introduced or very tolerant forms; hybrids common ,disease, fin damage ,other anomalies regular
No fish Repetitive sampling fails to turn up any fish
Parameters used in assessment of fish communitiesSpecies composition & richness
Ecological factors Number of species Presence of intolerant
species Species richness &
composition of Darters,Suckers,Sunfish
Proportion of Hybrid individuals
Number of individuals in sample
Proportion of Omnivores
Proportion of Insectivores
Proportion of top carnivores
Proportion with disease ,tumor, fin damage, other anomalies
IBI system
Several species composition metrics are evaluated
Each fish species has characteristic tolerance for water quality ,habitat,& other conditions
Within each family,sets of species may be ranked for their tolerances
Cont…
Presence of intolerant species is an important criterion
Eg of intolerant species found in mid-western warm waters include rock bass. Banded darter,longear sunfish….
Another metrics is the presence & abundance of green sunfish ,often the dominant or only sunfish present at degraded sites(>20% of individuals indicate degraded condition)
Presence of hybrids
Hybridization probably occurs as a result of habitat degradation
Frequency of hybrids seems to increase in modified streams
Finally in very degraded conditions, hybrids of carp & goldfish become quite common
Ecological factors
When a site declines in quality ,the proportion of individuals that are omnivores increases
The most degraded streams are commonly support large population of the omnivores(gold fish)
Their dominance is due to degradation of food base, especially invertebrates.
Cont…
<20% of individuals as omnivores as good>45% omnivores to be badly degraded Presence of top carnivore is another
important indicator
Viable & healthy population of top carnivore species indicate a relatively healthy,trophically diverse community
References
Assessment of biotic integrity using fish communities. Karr, J. R. 1981
U.S.Environmental protection agency (EPA)”BIOLOGICAL INTEGRITY”
