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Effects of a variable hydrograph on ...

Weibell, Benjamin J.

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Effects of a variable hydrograph on wood-dwelling invertebrate production and assemblage dynamics in medium-sized rivers.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Effects of a variable hydrograph on wood-dwelling invertebrate production and assemblage dynamics in medium-sized rivers./
Author:	Weibell, Benjamin J.
Description:	267 p.
Notes:	Adviser: Arthur C. Benke.
Contained By:	Dissertation Abstracts International68-07B.
Subject:	Biology, Ecology. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3270513
ISBN:	9780549107521

Effects of a variable hydrograph on wood-dwelling invertebrate production and assemblage dynamics in medium-sized rivers.
Weibell, Benjamin J.

Effects of a variable hydrograph on wood-dwelling invertebrate production and assemblage dynamics in medium-sized rivers. - 267 p.

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 &sim;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.

ISBN: 9780549107521Subjects--Topical Terms:

1017726
Biology, Ecology.

Effects of a variable hydrograph on wood-dwelling invertebrate production and assemblage dynamics in medium-sized rivers.
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020 $a 9780549107521
035 $a (UMI)AAI3270513
035 $a AAI3270513
040 $a UMI $c UMI
100 1 $a Weibell, Benjamin J. $3 1281494
245 1 0 $a Effects of a variable hydrograph on wood-dwelling invertebrate production and assemblage dynamics in medium-sized rivers.
300 $a 267 p.
500 $a Adviser: Arthur C. Benke.
500 $a Source: Dissertation Abstracts International, Volume: 68-07, Section: B, page: 4241.
502 $a Thesis (Ph.D.)--The University of Alabama, 2007.
520 $a 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 &sim;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.
590 $a School code: 0004.
650 4 $a Biology, Ecology. $3 1017726
650 4 $a Biology, Limnology. $3 1018638
650 4 $a Environmental Sciences. $3 676987
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710 2 0 $a The University of Alabama. $3 1019361
773 0 $t Dissertation Abstracts International $g 68-07B.
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790 1 0 $a Benke, Arthur C., $e advisor
791 $a Ph.D.
792 $a 2007
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3270513