Hydrogeologic delineation of habitats for endangered species: the Comal Springs/River System

Crowe, J. C.; Sharp, John M.

doi:10.1007/s002540050128

Cited by 13 publications

(14 citation statements)

References 5 publications

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“…Published values based on laboratory tests suggest that growth is inhibited at velocities greater than 0.8 m/s; however, no values have been published for natural environments and it is suspected that the inhibiting velocity is much greater (Horner et al 1990). The velocity chosen is within the range of velocities suggested for gravel and cobble bed overturn by river hydraulics (Crowe and Sharp 1997). The scouring factor was increased by a factor of three to cause greater scouring of the periphyton community once the water reached scouring velocity, so as to match the patterns observed in the Bow River 2006 sampling study.…”

Section: Calibration and Validationmentioning

confidence: 95%

Modelling aquatic vegetation and dissolved oxygen after a flood event in the Bow River, Alberta, Canada

et al. 2009

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Traditionally, macrophyte density has been considered the primary factor affecting the large dissolved oxygen fluctuations in the Bow River. After a major flood event scoured macrophytes in 2005, and subsequently changed river dynamics, the City of Calgary needed to update their predictive computer model for water quality to reflect the new conditions, which led to this study. A 2006 aquatic vegetation survey was also completed to assess post-flood conditions. The survey found that the average macrophyte dry weight was much lower (28 g/m 2 ± 100 (p = 0.05)) than the historic average of 241 g/m 2 ± 29, while the average periphyton chlorophyll-a concentration was higher (343 mg/m 2 ± 71) than the historic average (158 mg/m 2 ± 17)). Dissolved oxygen (DO) fluctuations were similar to pre-flood levels despite changes in the dominant vegetation. Using the results of this survey, the significant and previously unrecognized effects of periphyton diurnal processes on DO concentrations in the Bow River were identified and the Bow River water quality model (BRWQM) was recalibrated to reflect these findings. Adjustments were made to the BRWQM's periphyton submodel to account for the more dominant role played by these organisms in river processes, and a competitive shading factor between macrophytes and periphyton was also introduced to more accurately model the species' competition for available sunlight. This newly calibrated and validated version of BRWQM was tested and found capable of predicting the occurrence of low DO concentrations in the Bow River and can provide a useful tool for forecasting the water quality effects of the city's planned wastewater infrastructure expansion.Résumé : Traditionnellement, la densité en macrophytes a été considérée comme étant le principal facteur relié à de fortes fluctuations en oxygène dissous dans la rivière Bow. Après le lessivage des macrophytes par une inondation majeure en 2005 et le changement subséquent dans la dynamique de la rivière, la Ville de Calgary a demandé la mise à niveau de son modèle informatique prédictif sur la qualité de l'eau pour les nouvelles conditions déterminées lors d'un relevé de la végé-tation aquatique en 2006. Le relevé a permis de découvrir que le poids sec moyen de macrophytes (28 g/m 2 ± 100 (p = 0.05)) beaucoup plus bas que la moyenne historique de 241 g/m 2 ± 29 alors que la moyenne de la concentration en chlorophylle-a du périphyton était plus élevée (343 mg/m 2 ± 71) que la moyenne historique de 158 mg/m 2 ± 17. Les fluctuations de la teneur en oxygène dissous étaient similaires aux teneurs avant l'inondation malgré les changements dans la végéta-tion dominante. Les effets importants, et antérieurement inconnus, des processus diurnes du périphyton sur les concentrations en oxygène dissous ont été identifiés et le modèle de la qualité de l'eau de la rivière Bow (« BRWQM ») a été étalonné de nouveau pour refléter ces conclusions. Le sous-modèle de périphyton du « BRWQM » a été ajusté afin de tenir compte du rôle plus dominant joué par ces organi...

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Section: Calibration and Validationmentioning

confidence: 95%

Modelling aquatic vegetation and dissolved oxygen after a flood event in the Bow River, Alberta, Canada

et al. 2009

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“…Therefore, high discharges from the springs that create faster flows could restrict T. granifera from achieving higher densities in lotic habitats where native E. comalensis achieve their highest densities. Conversely, when spring flow declines due to pumping of the underground aquifer and/or droughts that cause reduced spring flows (Bowles & Arsuffi, 1993;Crowe & Sharp, 1997), the conditions could become more lentic. Under increasingly lentic conditions, T. granifera densities could increase in the reduced flows of the spring runs, inducing stronger interactions and possible competitive exclusion of E. comalensis.…”

Section: Interactions Of Native and Exotic Snails And Their Distributmentioning

confidence: 96%

“…Hydrologic alterations to the river from both channelization and dam construction have converted much of the upper river from free-flowing lotic habitats to lentic ones. The impoundment of the headwaters of the river resulted in an 8.4 ha reservoir (Landa Lake) with four spring-runs that flow into the lake (Ogden et al, 1986;Crowe & Sharp, 1997).…”

Section: Study Sitementioning

confidence: 98%

“…1). Spring Run 1 (SR1) is the largest spring run with an average discharge of 600 L s -1 , length of 180 m and an average width of 10 m. Spring Run 3 (SR3) has an average discharge between 300 and 600 L s -1 , a length of 138 m, and an average width of 8 m (Crowe and Sharp, 1997). The confluence (Confluence) of SR1 and Spring Run 2 (Spring Run 2 was not used in this study due to use as a public swimming area) served as one lentic site and is a channelized, deep reach with a length of 110 m and an average width of 20 m. The second lentic site was chosen within Landa Lake near an island (Island) and samples from this location were taken along a 100 m transect (Transect 1) and a perpendicular 25 m transect between the islands (Transect 2).…”

Section: Study Sitementioning

confidence: 99%

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Habitat influences snail community structure and trematode infection levels in a spring-fed river, Texas, USA

Tolley-Jordan

Owen

2007

Hydrobiologia

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The spring-fed Comal River in Texas, USA, has been impounded and channelized resulting mainly in a lentic environment with four headwater spring runs. We sampled two spring runs (lotic sites) and two lentic sites seasonally from April 2001 through April 2002 to assess (1) co-occurrence of native and exotic snail species (as determined by interspecific association), (2) the importance of habitat conditions in structuring relationships among these species, and (3) the distribution of snails infected with exotic trematode parasites. Three exotic and four endemic species of aquatic snails were collected, but only Elimia comalensis (Prosobranchia: Pleuroceridae, native), Melanoides tuberculatus, and Tarebia granifera (Prosobranchia: Thiaridae, exotic) were in sufficient densities for further analyses.Tarebia granifera was positively associated with both M. tuberculatus (v 2 = 18.5, P \ 0.001) and E. comalensis (v 2 = 7.3, P \ 0.01), although the cooccurrence between the two exotics was much stronger. Melanoides tuberculatus and E. comalensis exhibited a strong, negative association (v 2 = 10.9, P \ 0.001). The weaker co-occurrence between E. comalensis with the thiarids appeared to be driven by differences in habitat use by the thiarids and native E. comalensis. In lentic habitats, densities of M. tuberculatus and T. granifera were similar but differed significantly from E. comalensis whose densities were 200 times less than the exotic snails. In lotic spring runs, densities of T. granifera and E. comalensis were similar, but differed significantly from M. tuberculatus whose densities were 10 times fewer. Lower densities of M. tuberculatus and T. granifera in habitat conditions common to the spring runs may explain why exotic snail interactions were less with the native E. comalensis than with each other. The native snail, E. comalensis, was not infected with any trematodes, while 6.1% of M. tuberculatus and 4.8% of T. granifera were infected with exotic trematodes. Distributions of infected snails were aggregated; such that most infected snails were found in lentic habitats with silt substrates and moderate to high levels of detritus. Continued declines in spring-flows due to aquifer withdrawals and droughts will increase lentic habitats that may lead to increased densities of T. granifera and M. tuberculatus and their concomitant parasites.

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“…Spring-influenced lotic ecosystems often exhibit high diversity and levels of endemism, but also face anthropogenic stressors (Bowles & Arsuffi, 1993;Crowe & Sharp, 1997;Earl & Wood, 2002). Because spring-influenced ecosystems exhibit low variability in physicochemical conditions, they are particularly sensitive to the successful invasion of non-native species (Moyle & Light, 1996b).…”

Section: Introductionmentioning

confidence: 99%

Nutrient enrichment scarcely affects ecosystem impacts of a non‐native herbivore in a spring‐fed river

et al. 2014

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1. Non-native invasive species (NNIS) are a global issue whose introduction into novel ecosystems can fundamentally alter nutrient recycling and storage. It is therefore important to understand factors that affect the abundance and distribution of NNIS and their effects on ecosystems. 2. We investigated how nutrient enrichment and herbivorous armoured catfish separately and in combination affect ecosystem processes in a subtropical spring-fed river (San Marcos, River, TX, U.S.A.). A replicated stream channel experiment in which nutrient enrichment was cross-classified with the presence and the absence of armoured catfish was conducted to evaluate how nutrient enrichment may affect the ecosystem and nutrient cycling effects of catfish. 3. The presence of catfish reduced periphyton biomass and altered detrital decomposition rates and, contrary to predictions, decreased periphyton N:P. In addition, the presence of catfish increased the severity of periphyton P-limitation. We found little evidence that adding nutrients altered the effects of armoured catfish on ecosystem dynamics. 4. Armoured catfish likely play an important role in the nutrient dynamics of the San Marcos River, but nutrient enrichment has little influence on determining the magnitude of ecosystem and nutrient cycling effects of this invasive and stoichiometrically unique consumer.

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Hydrogeologic delineation of habitats for endangered species: the Comal Springs/River System

Cited by 13 publications

References 5 publications

Modelling aquatic vegetation and dissolved oxygen after a flood event in the Bow River, Alberta, Canada

Modelling aquatic vegetation and dissolved oxygen after a flood event in the Bow River, Alberta, Canada

Habitat influences snail community structure and trematode infection levels in a spring-fed river, Texas, USA

Nutrient enrichment scarcely affects ecosystem impacts of a non‐native herbivore in a spring‐fed river

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