HR: 14:45h
AN: NB43A-06    [Abstracts]
TI: Order, Family, Genus, Species: How Does Choice of Taxonomic Resolution Affect Multivariate Statistical Outcome?
AU: * Arscott, D B
EM: darscott@stroudcenter.org
AF: Stroud Water Research Center, 970 Spencer Road, Avondale, PA 19311 United States
AU: Jackson, J K
EM: jkjackson@stroudcenter.og
AF: Stroud Water Research Center, 970 Spencer Road, Avondale, PA 19311 United States
AU: Kratzer, E B
EM: ekratzer@stroudcenter.org
AF: Stroud Water Research Center, 970 Spencer Road, Avondale, PA 19311 United States
AB: Taxonomic resolution is an important component of community analyses and may affect statistical recognition of biological responses to environmental conditions. A 60-site macroinvertebrate dataset collected from New York City water supply watersheds was examined for taxonomic resolution effects on indirect gradient analyses, specifically correspondence analysis (CA) and non-metric multidimensional scaling (NMDS). Environmental gradients were significantly correlated with species assemblages in the two study regions, East (EOH) and West of Hudson River (WOH). WOH sites contained 464 taxonomic units (mostly species, including chironomids) from 87 families in 22 orders. EOH sites contained 435 "species" from 80 families in 24 orders. CA clearly separated EOH from WOH sites at all taxonomic levels but order using raw densities, relative abundance, and presence/absence datasets. This indicated strong biogeographic differences at family but not order level. Within each region, NMDS clearly separated impacted sites at species and genera levels, but family and order level ordinations only separated severely impacted EOH sites and did not separate WOH sites along established environmental gradients. Taxonomic differences reflecting biogeography were apparent at gross and fine taxonomic levels but genus/species level contributed to the identification of mild impact gradients and differentiation of severe impact within regions.
UR: http://www.stroudcenter.org/research/nyproject
DE: 9350 North America
DE: 9810 New fields (not classifiable under other headings)
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly