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Aquatic Ecology 303-47900

Aquatic Ecology 303-47900. what determines co-occurrence of species in a water body? structured communities, or random species assemblages? if structured: by biotic factors, or abiotic factors (or both)? if different patterns of resource use:

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Aquatic Ecology 303-47900

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  1. Aquatic Ecology303-47900

  2. what determines co-occurrence of species in a water body? structured communities, or random species assemblages? if structured: by biotic factors, or abiotic factors (or both)? if different patterns of resource use: is it resource partitioning, or coincidental differences? a species may specialize on certain foods or living in certain habitats to increase efficiency, while coincidentally, other species specialize in different ways

  3. intraspecific vs. interspecific exploitation vs. interference resource partitioning many studies in aquatic communities fail to show competition competition: review

  4. Paradox of plankton: assumptions: predict: one species should suceed, drive others out reality: typical mesotrophic & oligotropic lakes have 10-100 species of phytoplankton present at one time

  5. suggested reasons: changing environmental conditions, so shifting advantage selective grazing on dominant competitor reduces competition different nutrients limit different species probably is some combination of factors

  6. sampled 8 riffles in a parent stream and its major upstream tributary compared biophysical features of environment 5 spp. of Hydropsychidae: Spatial variability of Hydropsychidae

  7. stepwise regression numbers of each spp. vs. environmental variables seston quality was important for 2 species

  8. distribution of blackflies has been shown to relate to abiotic conditions in physically dissimilar streams sampled 18 physically similar streams in Yellowstone temp., current, depth, pH are all within range of species at least 30 species collected, looked at co-occurrence ran Monte Carlo simulations based 3 different models species assemblages of larval blackflies

  9. southern Appalachian mtns 13 sympatric species, seem to occupy the same ecological niche examined diatom assemblages in their diet, among species within and between discrete microhabitats species are selective feeders multivariate stats (ordination) niche overlap of sympatric Blephaceria larvae

  10. Zebra mussel invasion into Lake Huron: massive build-up in 1992 corresponding increased light penetration, shift in algal species extreme cases: alien mussel invasions

  11. Zebra Mussels(Dreissena polymorpha) affect native species, by: depleting food resources fouling the shells of native spp. net effect: reduced numbers or local extinction of native species

  12. Asian Clam (Corbicula fluminea) first appeared in NorthWest, then in Ohio R., and now spreading through E. North America appear to affect native mussels: typically have non-overlapping spatial distributions growth rates of native species are negatively correlated with #’s of Asian clams

  13. use organisms to evaluate water quality approaches: indicator species tolerant species (e.g., tubificid worms, red midge larvae) bioaccumulation toxins &/or heavy metals incorporated into organisms deformities community structure Biomonitoring

  14. metrics (quantitative representation of community) species/taxa richness, diversity index Hilsenhoff Biotic Index (also, Family Biotic Index) sum (siti)/Nwhere s = species, t = tolerance score EPT index (# of families), %EPT EPT/chironomid abundances ratio scrapers to filter-feeders, or ratio shredders to total community structure

  15. 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:

  16. 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

  17. 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)

  18. comparison of precision and accuracy compared to classification

  19. 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

  20. 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

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