1 / 24

Aquatic Ecology 303-47900

Aquatic Ecology 303-47900. metrics (quantitative representation of community) species/taxa richness, diversity index Hilsenhoff Biotic Index (also, Family Biotic Index) each organism has a tolerance value sum (s i t i )/N where s = species, t = tolerance score

Pat_Xavi
Télécharger la présentation

Aquatic Ecology 303-47900

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Aquatic Ecology303-47900

  2. metrics (quantitative representation of community) species/taxa richness, diversity index Hilsenhoff Biotic Index (also, Family Biotic Index) each organism has a tolerance value sum (siti)/Nwhere s = species, t = tolerance score EPT index (# of families), %EPT focus on Ephemeroptera, Plecoptera, Trichoptera families EPT/chironomid abundances ratio scrapers to filter-feeders, or ratio shredders to total community structure

  3. trade-off loss of precision & accuracy with lower cost quantitative vs. qualitative ID to order, family, or species? Hydropsyche sparna 6, H. phalerata 1, Parapsyche 0 variation among habitats within stream variance based on geography multimetrics: combining a number of metrics RPB - rapid bioassessment protocols standards based on bioregions use of reference streams problems with metrics:

  4. multimetric: calculate a score based on a formula, compare it to score generated from reference streams from the region multivariate: construct a model based upon a large number of sites sampled and related through multivariate statistics multimetric vs. multivariate methods

  5. multimetric: total abundance number of families % EPT individuals % Chironomidae # EPT indiv/(#EPT+chiron.) # hydropsych/#trichop %dominance Family Biotic Index (FBI) multivariate: BEAST (Benthic Assessment of Sediment) AusRivAS (Australian River Assessment Scheme)

  6. comparison of precision and accuracy compared to classification

  7. Oregon study: 6 sites, 43-58 samples/site ID to genus Classification Strength (CS) within site similarity vs. between site similarity larger is better determine relationships CS vs. # of surber samples CS vs. # of organisms sampled type of similarity index effect of sampling effort: multivariate models

  8. magnitude of variation depends on type of biotic measure sampled 4 creeks within one catchment basin and ecoregion yearly over 4-5 years; used multimetric methods compared CV of single streams among years & multiple streams within year within year / among year variation

  9. migration: periodic locomotion, not for daily maintenance dispersal: permanent change in location gene flow: change in gene pools (i.e., frequency of alleles) due to movement of individuals between populations migration, dispersal, gene flow

  10. below the thermocline by day, migrate up nightly migration: zooplankton in lakes

  11. Drift: • downstream transport in the water column • primarily swept downstream by current • invertebrates, larval fish • short-duration association with water column • significant for • downstream dispersal • food source for suspension-feeders

  12. periodicity • most drift occurs at night • peak just after dusk, may rise just before dawn

  13. why drift at night? • avoid visual predators • after contact with night-active tactile predators • mechanism? • partially genetic, partially environmental

  14. also drift when food is limiting

  15. what types and proportions of the insects drift? study of 2 headwater streams: input vs. output <1% of annual mean density <4% of annual mean biomass <1% of annual invertebrate production of floodplains

  16. most leaving in drift were copepods, chironomids, and ostracods (78-88% of individuals; net output) net input primarily mayflies, caddisflies, and isopods (misc. were primarily odonates and megalopterans)

  17. dilema: how to compensate for drift dispersal • upstream crawling by juveniles • Leptophlebia sp. mayflies crawl 200 m / day, a total of 1.6 km • also contributes to initial colonization of streams • upstream crawling typically compensates for 2 - 15% of downstream drift dispersal • upstream flying by adults

  18. what is most important for dispersal? • drift as juveniles or is flight by adults? • answer is obvious for crustaceans • studies in population genetics:

  19. dispersal by freshwater shrimp (Paratya australiensis) live in Australian upland streams planktonic larvae drift, plus can walk upstream as adult examined allele frequencies (6 loci - only 1 shown) ca. 200 km between estuaries of these rivers large difference in genetic structure between streams, but not greater between 2 drainage systems

  20. how effective is dispersal in stream insects? comparison with 3 types of Australian invertebrates Baetis sp. mayfly Rheumatometra sp. water strider Tasiagma sp. caddisfly data indicates limited within-stream movement, probably only a few females colonizing, but genetic blending over streams & catchments

  21. permanent ponds: both metamorphic and paedomorphic salamanders temporary ponds: dispersal of fairy shrimp(study in the Rocky Mtns)

  22. fairy shrimp eggs hatch: if passed through a salamander if live females or just egg sacs are put in a pond

  23. population genetics of fairy shrimps: more similar within valleys than between valleys

More Related