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作者 Weibell, Benjamin J
書名 Effects of a variable hydrograph on wood-dwelling invertebrate production and assemblage dynamics in medium-sized rivers
國際標準書號 9780549107521
book jacket
說明 267 p
附註 Source: Dissertation Abstracts International, Volume: 68-07, Section: B, page: 4241
Adviser: Arthur C. Benke
Thesis (Ph.D.)--The University of Alabama, 2007
The effects of natural water level variation on wood-dwelling invertebrates were examined in the Sipsey River, a Coastal Plain river in west central Alabama. Habitat distribution, invertebrate evacuation, variations in drift and colonization patterns, and monthly depth-specific production were measured. Wood surface area was 0.463 m2 of wood per m2 of channel and volume was 0.0173 m3 per m2 of channel. Other low-gradient forested rivers have comparable wood loadings, and vertical patterns of wood distribution were consistent in these rivers with ∼50-70% of wood submerged at low flows. When invertebrates on snags were exposed to air, they evacuated when desiccation was imminent. Evacuation peaked at 2-4 h with most animals leaving snags within 24 h, but evacuation lasting for 7 d. Mortality for the entire period was high (85-92%), but evacuating animals made up 75 to almost 100% of original biomass. Mean colonization and drift density and biomass were higher during falling water than rising water. Over 7 d, colonization efficiencies were low (density 14.75%, biomass 3.86%), but varied seasonally and between taxa. Vertical patterns of invertebrate distribution correlated strongly with several hydrologic variables. Distribution appeared to be determined by taxon-specific responses to recent hydrological events. Multiple regression models predicted vertical distribution of abundance, biomass, production, turnover rate, and mean animal size from hydrologic variables. Also, a study was made of a human-induced desiccation event in the Rio Grande, New Mexico, a Basin and Range river. Despite lower abundance of wood habitat in the Rio Grande, invertebrate abundance, biomass and diversity were comparable to the Sipsey. Abundance at a desiccated site recovered in 2 wk, but taxonomic composition was still different after 12 wk. Overall, the wood-dwelling invertebrate community demonstrated little resistance, but high resilience, to desiccation events. Resilience is most likely a function of the abundance of habitat and high turnover rates. Drift and colonization are important mechanisms for evacuation during habitat contraction and dispersal during habitat expansion
School code: 0004
Host Item Dissertation Abstracts International 68-07B
主題 Biology, Ecology
Environmental Sciences
Biology, Limnology
Alt Author The University of Alabama
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