2002
Finlay, Jacques C.; Khandwala, Sapna; Power, Mary E.
Spatial scales of carbon flow in a river food web Journal Article
In: Ecology, vol. 83, no. 7, pp. 1845-1859, 2002.
Abstract | Links | BibTeX | Tags: cannibalism, carbon and nitrogen stable-isotope ratios, carbon flow, Oncorhynchus mykiss, river food webs, scraper and collector-gatherer (SCG) taxa, spatial scale, steelhead trout, terrestrial detritus, trophic structure
@article{Finlay2002,
title = {Spatial scales of carbon flow in a river food web},
author = {Jacques C. Finlay and Sapna Khandwala and Mary E. Power},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Spatial-scales-of-energy-flow-in-food-webs-of-the-South-Fork-Eel-River_Finlay_2002.pdf},
doi = {10.2307/3071769},
year = {2002},
date = {2002-00-00},
journal = {Ecology},
volume = {83},
number = {7},
pages = {1845-1859},
abstract = {Spatial extents of food webs that support stream and river consumers are largely unknown, but such information is essential for basic understanding and management of lotic ecosystems. We used predictable variation in algal δ13C with water velocity, and measurements of consumer δ13C and δ15N to examine carbon flow and trophic structure in food webs of the South Fork Eel River in Northern California. Analyses of δ13C showed that the most abundant macroinvertebrate groups (collector-gatherers and scrapers) relied on algae from local sources within their riffle or shallow pool habitats. In contrast, filter-feeding invertebrates in riffles relied in part on algal production derived from upstream shallow pools. Riffle invertebrate predators also relied in part on consumers of pool-derived algal carbon. One abundant taxon drifting from shallow pools and riffles (baetid mayflies) relied on algal production derived from the habitats from which they dispersed. The trophic linkage from pool algae to riffle invertebrate predators was thus mediated through either predation on pool herbivores dispersing into riffles, or on filter feeders. Algal production in shallow pool habitats dominated the resource base of vertebrate predators in all habitats at the end of the summer. We could not distinguish between the trophic roles of riffle algae and terrestrial detritus, but both carbon sources appeared to play minor roles for vertebrate consumers. In shallow pools, small vertebrates, including three-spined stickleback (Gasterosteus aculeatus), roach (Hesperoleucas symmetricus), and rough-skinned newts (Taricha granulosa), relied on invertebrate prey derived from local pool habitats. During the most productive summer period, growth of all size classes of steelhead and resident rainbow trout (Oncorhynchus mykiss) in all habitats (shallow pools, riffles, and deep unproductive pools) was largely derived from algal production in shallow pools. Preliminary data suggest that the strong role of shallow pool algae in riffle steelhead growth during summer periods was due to drift of pool invertebrates to riffles, rather than movement of riffle trout. Data for δ15N showed that resident rainbow trout (25-33 cm standard length) in deep pools preyed upon small size classes of juvenile steelhead that were most often found in riffles or shallow pools. While many invertebrate consumers relied primarily on algal production derived from local habitats, our study shows that growth of top predators in the river is strongly linked to food webs in adjacent habitats. These results suggest a key role for emigration of aquatic prey in determining carbon flow to top predators.},
keywords = {cannibalism, carbon and nitrogen stable-isotope ratios, carbon flow, Oncorhynchus mykiss, river food webs, scraper and collector-gatherer (SCG) taxa, spatial scale, steelhead trout, terrestrial detritus, trophic structure},
pubstate = {published},
tppubtype = {article}
}
Spatial extents of food webs that support stream and river consumers are largely unknown, but such information is essential for basic understanding and management of lotic ecosystems. We used predictable variation in algal δ13C with water velocity, and measurements of consumer δ13C and δ15N to examine carbon flow and trophic structure in food webs of the South Fork Eel River in Northern California. Analyses of δ13C showed that the most abundant macroinvertebrate groups (collector-gatherers and scrapers) relied on algae from local sources within their riffle or shallow pool habitats. In contrast, filter-feeding invertebrates in riffles relied in part on algal production derived from upstream shallow pools. Riffle invertebrate predators also relied in part on consumers of pool-derived algal carbon. One abundant taxon drifting from shallow pools and riffles (baetid mayflies) relied on algal production derived from the habitats from which they dispersed. The trophic linkage from pool algae to riffle invertebrate predators was thus mediated through either predation on pool herbivores dispersing into riffles, or on filter feeders. Algal production in shallow pool habitats dominated the resource base of vertebrate predators in all habitats at the end of the summer. We could not distinguish between the trophic roles of riffle algae and terrestrial detritus, but both carbon sources appeared to play minor roles for vertebrate consumers. In shallow pools, small vertebrates, including three-spined stickleback (Gasterosteus aculeatus), roach (Hesperoleucas symmetricus), and rough-skinned newts (Taricha granulosa), relied on invertebrate prey derived from local pool habitats. During the most productive summer period, growth of all size classes of steelhead and resident rainbow trout (Oncorhynchus mykiss) in all habitats (shallow pools, riffles, and deep unproductive pools) was largely derived from algal production in shallow pools. Preliminary data suggest that the strong role of shallow pool algae in riffle steelhead growth during summer periods was due to drift of pool invertebrates to riffles, rather than movement of riffle trout. Data for δ15N showed that resident rainbow trout (25-33 cm standard length) in deep pools preyed upon small size classes of juvenile steelhead that were most often found in riffles or shallow pools. While many invertebrate consumers relied primarily on algal production derived from local habitats, our study shows that growth of top predators in the river is strongly linked to food webs in adjacent habitats. These results suggest a key role for emigration of aquatic prey in determining carbon flow to top predators.
2001
Finlay, Jacques C.; Power, Mary E.
In: Technical Completion Report, vol. UCAL-WRC-W-906, 2001.
Abstract | Links | BibTeX | Tags: cannibalism, Carbon and nitrogen stable isotope ratios, energy flow, Oncorhynchus mykiss, river food webs, river-watershed exchange, spatial scale, steelhead trout, terrestrial detritus, trophic structure
@article{Power2001,
title = {Carbon isotope signatures and spatial scales of energy flow in food webs supporting salmonids in food webs supporting salmonids in Northern California rivers},
author = {Jacques C. Finlay and Mary E. Power},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/eScholarship-UC-item-79t2s4f8.pdf},
year = {2001},
date = {2001-05-01},
journal = {Technical Completion Report},
volume = {UCAL-WRC-W-906},
abstract = {Spatial scales of the food webs that support the growth of juvenile salmonids in California rivers are largely unknown, but such information is essential for management of flows, species, and other ecosystem factors influencing salmonid production. Our project objectives were:
1. to determine whether predictable variation in algal d13C with water velocity, and measurements of consumer d13C and d15N could be used to examine energy flow and trophic structure in food webs of the South Fork Eel River, and other salmon-bearing streams in Northern California, and
2. to provide this information as a basis for examining how changes in access to energy sources following river regulation or invasions of exotic species might influence the access of various web members, including salmonids, to these sources.},
keywords = {cannibalism, Carbon and nitrogen stable isotope ratios, energy flow, Oncorhynchus mykiss, river food webs, river-watershed exchange, spatial scale, steelhead trout, terrestrial detritus, trophic structure},
pubstate = {published},
tppubtype = {article}
}
Spatial scales of the food webs that support the growth of juvenile salmonids in California rivers are largely unknown, but such information is essential for management of flows, species, and other ecosystem factors influencing salmonid production. Our project objectives were:
1. to determine whether predictable variation in algal d13C with water velocity, and measurements of consumer d13C and d15N could be used to examine energy flow and trophic structure in food webs of the South Fork Eel River, and other salmon-bearing streams in Northern California, and
2. to provide this information as a basis for examining how changes in access to energy sources following river regulation or invasions of exotic species might influence the access of various web members, including salmonids, to these sources.
1. to determine whether predictable variation in algal d13C with water velocity, and measurements of consumer d13C and d15N could be used to examine energy flow and trophic structure in food webs of the South Fork Eel River, and other salmon-bearing streams in Northern California, and
2. to provide this information as a basis for examining how changes in access to energy sources following river regulation or invasions of exotic species might influence the access of various web members, including salmonids, to these sources.
Finlay, Jacques C.
Stable-carbon-isotope ratios of river biota: Implications for energy flow in lotic food webs Journal Article
In: Ecology, vol. 82, no. 4, pp. 1052-1064, 2001, ISSN: 0012-9658.
Abstract | Links | BibTeX | Tags: algae, carbon limitation, energy flow, lotic food webs, stable-carbon-isotope ratios, terrestrial detritus, watershed area, δ13C
@article{Finlay2001,
title = {Stable-carbon-isotope ratios of river biota: Implications for energy flow in lotic food webs},
author = {Jacques C. Finlay},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/STABLE-CARBON-ISOTOPE-RATIOS-OF-RIVER-BIOTA-IMPLICATIONS-FOR-ENERGY-FLOW-IN-LOTIC-FOOD-WEBS_Finlay_2001.pdf},
doi = {10.1890/0012-9658(2001)082[1052:SCIROR]2.0.CO;2},
issn = {0012-9658},
year = {2001},
date = {2001-04-00},
journal = {Ecology},
volume = {82},
number = {4},
pages = {1052-1064},
abstract = {Stable-isotope ratios of carbon (13C/12C or δ13C) have been widely used to determine the energy base of stream food webs, but such use is controversial due to unexplained variability in algal δ13C. I used published δ13C data from temperate headwater streams through medium-sized rivers (0.2–4000 km2 watershed area) collected during summer baseflows and original data from streams in northern California to analyze energy pathways through river food webs. The analyses showed three important results. First, epilithic algal δ13C and watershed area are positively related, suggesting that effects of carbon limitation on algal carbon uptake result in 13C enrichment of algal δ13C in larger, more productive rivers. Second, epilithic algae and terrestrial detritus δ13C values are often distinct in small shaded streams but overlap in some larger unshaded streams and rivers. Measurements of δ13C values may be most useful in distinguishing algal and terrestrial energy sources in unproductive streams with supersaturated dissolved CO2 concentrations, and some productive rivers where CO2 concentrations are low relative to photosynthetic rates. Finally, consumer δ13C values are more strongly related to algal δ13C than terrestrial δ13C. The relative contribution of terrestrial and algal carbon sources often varied by functional feeding group within and between sites. However, with the exception of shredders and scrapers, which respectively relied on terrestrial and algal carbon sources, patterns of consumer δ13C clearly show a transition from terrestrial to algal carbon sources for many lotic food webs in streams with ≥10 km2 watershed area. The observed transition to algal carbon sources is likely related to increasing primary production rates as forest canopy cover declines in larger streams, although decreasing retention or quality of terrestrial carbon may also play a role. Improved analyses of algal δ13C and δ15N combined with quantitative study of organic matter dynamics and food web structure should allow the relative importance of these factors to be distinguished in future food web studies.},
keywords = {algae, carbon limitation, energy flow, lotic food webs, stable-carbon-isotope ratios, terrestrial detritus, watershed area, δ13C},
pubstate = {published},
tppubtype = {article}
}
Stable-isotope ratios of carbon (13C/12C or δ13C) have been widely used to determine the energy base of stream food webs, but such use is controversial due to unexplained variability in algal δ13C. I used published δ13C data from temperate headwater streams through medium-sized rivers (0.2–4000 km2 watershed area) collected during summer baseflows and original data from streams in northern California to analyze energy pathways through river food webs. The analyses showed three important results. First, epilithic algal δ13C and watershed area are positively related, suggesting that effects of carbon limitation on algal carbon uptake result in 13C enrichment of algal δ13C in larger, more productive rivers. Second, epilithic algae and terrestrial detritus δ13C values are often distinct in small shaded streams but overlap in some larger unshaded streams and rivers. Measurements of δ13C values may be most useful in distinguishing algal and terrestrial energy sources in unproductive streams with supersaturated dissolved CO2 concentrations, and some productive rivers where CO2 concentrations are low relative to photosynthetic rates. Finally, consumer δ13C values are more strongly related to algal δ13C than terrestrial δ13C. The relative contribution of terrestrial and algal carbon sources often varied by functional feeding group within and between sites. However, with the exception of shredders and scrapers, which respectively relied on terrestrial and algal carbon sources, patterns of consumer δ13C clearly show a transition from terrestrial to algal carbon sources for many lotic food webs in streams with ≥10 km2 watershed area. The observed transition to algal carbon sources is likely related to increasing primary production rates as forest canopy cover declines in larger streams, although decreasing retention or quality of terrestrial carbon may also play a role. Improved analyses of algal δ13C and δ15N combined with quantitative study of organic matter dynamics and food web structure should allow the relative importance of these factors to be distinguished in future food web studies.