160 likes | 376 Views
Rapid Bioassessment Protocol (RBP). Background to RBP. changes in community/assemblage composition used to evaluate existence and degree of impact on an ecosystem Can infer functional changes by evaluating structural changes
E N D
Background to RBP • changes in community/assemblage composition used to evaluate existence and degree of impact on an ecosystem • Can infer functional changes by evaluating structural changes • Not designed to provide definitive answer, id systems needing in-depth evaluation • Base on two assessments • Biological assessment • Habitat assessment
Biological Assessment • Evaluates overall biological condition from a few samples (must keep seasonality in mind) • Assumes composition of benthic community will reflect an integrated response to environmental effects over time • Can be performed at many levels • 1st level is Functional Feeding Groups of benthic macroinvertebrates (mostly larval stages of aquatic insects)
Advantages of Using Benthic Macroinvertebrates • Limited migration = good for upstream/downstream evaluation • Usually have complex life cycle > 1 year can integrate long-term impact • Very quick and easy to determine degraded condition by experienced sampler • Sampling easy with few people, inexpensive, no detrimental effect on resident biota (no rotenone) • Benthic inverts usually abundant (and serve as food source) • State agencies often keep data bases on benthic mac. to be used for comparisons
Habitat Assessment • Evaluate habitat, then predict what stream organisms should be there • Is “poor” bioassessment due to poor habitat or ecosystem stress (or combination)?
Bottom substrate Embeddedness Flow Channel alteration Bottom scouring/ deposition >50% rubble, gravel, logs, other stable habitat < 25% surrounded by fine sediments Cold >0.05 cms (2 cfs); warm >0.15 cms (5 cfs) No enlargement of islands /bars, no channelization <5% of bottom affected by scouring and deposition Stream Habitat Assessment VariableExcellent Habitat
Pool/rifle, run/bend ratio (distance between riffles/stream width) Bank stability Bank vegetation Streamside cover 5 – 7 (>25 is poor) Stable (no evidence of erosion or bank failure > 80% of bank surfaces covered by vegetation, boulders or cobble Dominant vegetation is shrub, secondarily trees Stream Habitat Assessment VariableExcellent Habitat