Trophic Linkages in the Lower Colorado River: Multiple Stable Isotope Evidence

Angradi, Ted R.

doi:10.2307/1467845

Cited by 101 publications

(75 citation statements)

References 27 publications

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“…N values of periphyton (δ 15 N = 9.31‰ ± 1.22‰) were higher than those of terrestrial detritus across all sites (δ 15 N = 6.3‰ ± 0.17‰; t = −5.99, P < 0.001, df = 10). This is consistent with the findings of Angradi (1994), who indicated that dual isotope plots reveal that lotic algae, riparian vegetation, and upland vegetation had distinct isotope signatures.…”

Section: Discussionsupporting

confidence: 92%

“…The overall δ 13 C values of fish in channelized stretches are usually lower than those in natural ones and are generally close to those of algal carbon. Similarly to previous studies (Rosenfeld and Roff 1992, Angradi 1994, Coat et al 2009, Sullivan et al 2015) the fish assemblages of natural stretches were found to be more 13 C-enriched indicating their feeding on the terrestrial (riparian) food sources. Fish from the natural sites had isotopic labels much closer to terrestrial one than to aquatic carbon.…”

Section: Discussionsupporting

confidence: 82%

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Impact of the riverbed morphology on the source of organic material and the trophic structure of fish community along the upper reaches of the Nevėžis River, Lithuania

Čivas¹,

Kesminas²,

Barisevičiūtė³

2016

Acta Ichthyol. Piscat.

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Čivas L., Kesminas V., Barisevičiūtė R. 2016. Impact of the riverbed morphology on the source of organic material and the trophic structure of fish community along the upper reaches of the Nevėžis River, Lithuania. Acta Ichthyol. Piscat. 46 (4): 303-312.Background. The catchment of the Nevėžis River, the sixth longest river in Lithuania, is among the most affected by agricultural activities. Although seriously disturbed by land reclamation and agricultural pollution, the Nevėžis River still has natural, anthropogenically unaffected stretches. Fish species were studied at two sites of the upper part of the river with different hydrological regime, exhibiting clear differences in the trophic status of fish. The combined effect of hydrogeomorphic and water-chemistry variability on the stable isotope composition of fish assemblages in Lithuania has not been investigated. The presently reported study was intended to explore the possible effects of the riverbed morphology and agricultural activities on the chemistry and stable isotope composition of the three main fish species. Materials and methods. This study covered three species of freshwater fishes: the European perch, Perca fluviatilis Linnaeus, 1758; the roach, Rutilus rutilus (Linnaeus, 1758); and the northern pike, Esox lucius Linnaeus, 1758. The sampling was performed in both natural and regulated river stretches using backpack electrofishing equipment. Stable isotope composition of the samples was revealed by applying stable isotope analyses (SIA) with an elemental analyser connected to an isotope ratio mass spectrometer. To obtain more information about environmental variability and variation of stable isotopes δ 13 C and δ 15 N in fish, the entire data matrix was analysed using Principal Component Analysis (PCA). Results. In the study sites on the Nevėžis River, algal carbon isotope ratios were more 13 C-depleted than those from terrestrial sources. The fishes were clearly dependent on terrestrial carbon sources in natural locations. However, the fishes collected from regulated sites had carbon isotope signatures more similar to algal than to terrestrial sources. Mean values of δ 15 N of the fishes from the natural sites were lower than those from the regulated ones. Conclusion. The presently reported study revealed impact of abiotic habitat variables indicating the importance of physicochemical and morphological characteristics on δ 13 C and δ 15N isotopic values variance of fish at natural and regulated river sites. Our findings would help to evaluate and predict changes on river food webs that occur due to hydromorphological alterations determined by human activity and climate change. The results could be useful for fisheries, i.e., impact of environmental factors on fish nutrition and growth.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 82%

Impact of the riverbed morphology on the source of organic material and the trophic structure of fish community along the upper reaches of the Nevėžis River, Lithuania

Čivas¹,

Kesminas²,

Barisevičiūtė³

2016

Acta Ichthyol. Piscat.

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show abstract

“…It was suggested that the changes in d 13 C were due to a decreasing contribution of phytoplankton with downstream distance, but they could offer no explanation for the enrichment of 15 N in macrophytes. In contrast, Angradi (1994) observed depletion of 13 C and 15 N in seston in a downstream direction and no longitudinal variation in the isotopic composition of amphipods or fish for 25 km. Shannon et al (2001) observed enrichment of 13 C in benthic algae, macroinvertebrates and fish up to 350 km downstream of Glen Canyon Dam but no longitudinal trends in d 15 N for the same groups.…”

Section: Introductionmentioning

confidence: 56%

The effects of dams on longitudinal variation in river food webs

Growns¹,

Chessman

Mitrovic

et al. 2013

Journal of Freshwater Ecology

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“…The quality of overall rainbow trout habitat decreases precipitously below the Little Colorado River (Makinster and others, 2010). In the reach between Glen Canyon Dam and the Little Colorado River, the aquatic food web is fuelled almost exclusively by microscopic algae (Angradi, 1994;Shannon and others, 1994), invertebrate biomass is high (Stevens and others, 1997), and rainbow trout completely dominate the fish catch (Makinster and others, 2010).…”

Section: Aquatic Ecosystem Backgroundmentioning

confidence: 99%