2002
Sabo, John L.; Bastow, Justin L.; Power, Mary E.
Length-mass relationships for adult aquatic and terrestrial invertebrates in a California watershed Journal Article
In: Journal of the North American Benthological Society, vol. 21, no. 2, pp. 336-343, 2002, ISSN: 0887-3593.
Abstract | Links | BibTeX | Tags: biomass estimation, body size, energy flux, length-mass regression, river-watershed exchange
@article{Sabo2002c,
title = {Length-mass relationships for adult aquatic and terrestrial invertebrates in a California watershed},
author = {John L. Sabo and Justin L. Bastow and Mary E. Power},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Sabo_2002_JNABS.pdf},
doi = {10.2307/1468420},
issn = {0887-3593},
year = {2002},
date = {2002-06-00},
journal = {Journal of the North American Benthological Society},
volume = {21},
number = {2},
pages = {336-343},
abstract = {We collected 541 invertebrate specimens in riparian and upland habitats of the South Fork (SF) Eel River, California, USA, representing 12 orders and 55 families, and including adults of both aquatic and terrestrial origin. We fitted a power function to this data set at 4 taxonomic levels: 1) the entire pooled sample, 2) composite samples of aquatic and terrestrial taxa, 3) individual orders, and 4) individual families for which there were adequate data (n > 8; 24 families). Coefficients of determination (R-2) for length-mass relationships generally increased with increasing taxonomic specificity. Composite samples of aquatic and terrestrial taxa had significantly different length-mass relationships, with dry mass increasing faster with length in terrestrial taxa. Differences in length-dry mass relationships between aquatic and terrestrial taxa appeared to result from significantly higher slopes for terrestrial taxa in length-width relationships, and significantly lower slopes in length water content relationships. Our results suggest that the use of terrestrial regressions to estimate aquatic insect biomass flux in riparian habitats overestimates both the absolute magnitude of biomass flux as well as its relative importance to insect standing stocks. Development of unique regression algorithms for adult aquatic insect taxa increases the accuracy of aquatic insect biomass estimates in terrestrial habitats.},
keywords = {biomass estimation, body size, energy flux, length-mass regression, river-watershed exchange},
pubstate = {published},
tppubtype = {article}
}
We collected 541 invertebrate specimens in riparian and upland habitats of the South Fork (SF) Eel River, California, USA, representing 12 orders and 55 families, and including adults of both aquatic and terrestrial origin. We fitted a power function to this data set at 4 taxonomic levels: 1) the entire pooled sample, 2) composite samples of aquatic and terrestrial taxa, 3) individual orders, and 4) individual families for which there were adequate data (n > 8; 24 families). Coefficients of determination (R-2) for length-mass relationships generally increased with increasing taxonomic specificity. Composite samples of aquatic and terrestrial taxa had significantly different length-mass relationships, with dry mass increasing faster with length in terrestrial taxa. Differences in length-dry mass relationships between aquatic and terrestrial taxa appeared to result from significantly higher slopes for terrestrial taxa in length-width relationships, and significantly lower slopes in length water content relationships. Our results suggest that the use of terrestrial regressions to estimate aquatic insect biomass flux in riparian habitats overestimates both the absolute magnitude of biomass flux as well as its relative importance to insect standing stocks. Development of unique regression algorithms for adult aquatic insect taxa increases the accuracy of aquatic insect biomass estimates in terrestrial habitats.
Bastow, Justin L.; Sabo, John L.; Finlay, Jacques C.; Power, Mary E.
A basal aquatic-terrestrial trophic link in rivers: algal subsidies via shore-dwelling grasshoppers Journal Article
In: Oecologia, vol. 131, no. 2, pp. 261-268, 2002.
Abstract | Links | BibTeX | Tags: pygmy grasshopper, Riparian, river-watershed exchange, subsidy, tetrigidae
@article{Bastow2002,
title = {A basal aquatic-terrestrial trophic link in rivers: algal subsidies via shore-dwelling grasshoppers},
author = {Justin L. Bastow and John L. Sabo and Jacques C. Finlay and Mary E. Power},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/A-Basal-Aquatic-Terrestrial-Trophic-Link-in-Rivers-Algal-Subsidies-via-Shore-Dwelling-Grasshoppers_Bastow_2002.pdf},
doi = {10.1007/S00442-002-0879-7},
year = {2002},
date = {2002-03-14},
journal = {Oecologia},
volume = {131},
number = {2},
pages = {261-268},
abstract = {Rivers provide important resources for riparian consumers, especially in arid or seasonally arid biomes. Pygmy grasshoppers (Paratettix aztecus and P. mexicanus; Tetrigidae) graze river algae stranded along shorelines of the South Fork Eel River in northern California (39°44′N, 123°39′W) as the river recedes during the summer drought. Densities of tetrigids during the mid to late summer were highest (1 $textindividual/textm^2$ in July) within 1 m of the river margin, and declined to near zero at 4 m from the margin, especially during peak temperatures in the afternoon. These observations suggested that the distribution of tetrigids was determined by the availability of algae, water, or both. We manipulated the presence/absence of water and beached algae (Cladophora glomerata) in a 2×2 factorial design. All treatments were positioned 2 m upslope from the river's edge (about 30 cm above the water table), where the cobble bar was naturally dry and devoid of algae and densities of tetrigids were lower than at the river margin (0.4 individuals/m2 in July). Tetrigids responded only to the wet Cladophora treatment, which had 30× higher densities than other treatments. Stable isotopic signatures (δ 13C) of tetrigids (-19.7‰) collected from the same cobble bars were more similar to those of epilithic algae (-20.4‰) than terrestrial plants (-28.2‰), and higher than those of acridid grasshoppers (-27.9‰) from the same habitats. Mixing models suggest that 88-100% of the C in tetrigid grasshoppers at our study site is derived from riverine algae. A preliminary analysis suggests that tetrigids ingested sufficient quantities of algae to easily meet their energetic demands during the summer. This study supports the idea that algae, produced in stream systems, can determine the distribution and relative abundance of a common terrestrial scavenger and provide an additional pathway for energy exchange between rivers and riparian food webs.},
keywords = {pygmy grasshopper, Riparian, river-watershed exchange, subsidy, tetrigidae},
pubstate = {published},
tppubtype = {article}
}
Rivers provide important resources for riparian consumers, especially in arid or seasonally arid biomes. Pygmy grasshoppers (Paratettix aztecus and P. mexicanus; Tetrigidae) graze river algae stranded along shorelines of the South Fork Eel River in northern California (39°44′N, 123°39′W) as the river recedes during the summer drought. Densities of tetrigids during the mid to late summer were highest (1 $textindividual/textm^2$ in July) within 1 m of the river margin, and declined to near zero at 4 m from the margin, especially during peak temperatures in the afternoon. These observations suggested that the distribution of tetrigids was determined by the availability of algae, water, or both. We manipulated the presence/absence of water and beached algae (Cladophora glomerata) in a 2×2 factorial design. All treatments were positioned 2 m upslope from the river’s edge (about 30 cm above the water table), where the cobble bar was naturally dry and devoid of algae and densities of tetrigids were lower than at the river margin (0.4 individuals/m2 in July). Tetrigids responded only to the wet Cladophora treatment, which had 30× higher densities than other treatments. Stable isotopic signatures (δ 13C) of tetrigids (-19.7‰) collected from the same cobble bars were more similar to those of epilithic algae (-20.4‰) than terrestrial plants (-28.2‰), and higher than those of acridid grasshoppers (-27.9‰) from the same habitats. Mixing models suggest that 88-100% of the C in tetrigid grasshoppers at our study site is derived from riverine algae. A preliminary analysis suggests that tetrigids ingested sufficient quantities of algae to easily meet their energetic demands during the summer. This study supports the idea that algae, produced in stream systems, can determine the distribution and relative abundance of a common terrestrial scavenger and provide an additional pathway for energy exchange between rivers and riparian food webs.
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.