2002
Sabo, John L.; Power, Mary E.
River-watershed exchange: Effects of riverine subsidies on riparian lizards and their terrestrial prey Journal Article
In: Ecology, vol. 83, no. 7, pp. 1860-1869, 2002, ISSN: 0012-9658.
Abstract | Links | BibTeX | Tags: APPARENT COMPETITION, AQUATIC INSECTS, BENTHIC-PELAGIC LINKS, COMMUNITIES, FOOD-WEB, invertebrates, ISLANDS, MARINE, SECONDARY PRODUCTION, STREAM
@article{Sabo2002,
title = {River-watershed exchange: Effects of riverine subsidies on riparian lizards and their terrestrial prey},
author = {John L. Sabo and Mary E. Power},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/River-watershed-exchange-Effects-of-riverine-subsidies-on-riparian-lizards-and-their-terrestrial-prey_Sabo_2002.pdf},
issn = {0012-9658},
year = {2002},
date = {2002-07-00},
journal = {Ecology},
volume = {83},
number = {7},
pages = {1860-1869},
abstract = {Resource subsidies from external habitats can enhance the performance or population density of local consumers, altering their effects on in situ prey. Indirect effects of subsidies may be either positive or negative depending on the behavior of the shared consumer. Here we document strong links between riverine insects, riparian lizards (Sceloporus occidentalis), and terrestrial invertebrates. We hypothesized that aquatic insects subsidize riparian lizard populations leading to higher growth rates of these lizards in near-river habitats, and that subsidies exert short-term positive effects on terrestrial resources as a result of diet shifts by lizards to aquatic insects. To test these hypotheses, we used 2 m high fences, or "subsidy shields," to experimentally reduce aquatic insect flux to large (91 m 2) enclosures of lizards. Subsidy shields reduced aquatic insect flux by 55-65%. Growth rates of lizards were 7X higher in subsidized (no-shield) enclosures during the early summer but were not significantly different later in the summer, when ambient fluxes of aquatic insects dropped to 20% of their early season levels. Within the watershed, lizard growth rates (in mass) were positively correlated with the numerical abundance of aquatic insects. Thus, lizard growth rates tracked both seasonal and spatial availability of riverine insect subsidies during our experiment. Subsidies also had indirect effects on the ground-dwelling, terrestrial prey of lizards. Declines of diurnal terrestrial invertebrates Were significantly higher in shield than no-shield enclosures, and the most common ground spider (Arctosa sp. [Lycosidae]) disappeared completely from shield enclosures by the end of the experiment. Declines in terrestrial invertebrate abundance did not differ between no-shield enclosures and lizard exclosures. These data suggest that riverine insects subsidize riparian Sceloporus and, in the short term, reduce their predation on terrestrial arthropods.},
keywords = {APPARENT COMPETITION, AQUATIC INSECTS, BENTHIC-PELAGIC LINKS, COMMUNITIES, FOOD-WEB, invertebrates, ISLANDS, MARINE, SECONDARY PRODUCTION, STREAM},
pubstate = {published},
tppubtype = {article}
}
Resource subsidies from external habitats can enhance the performance or population density of local consumers, altering their effects on in situ prey. Indirect effects of subsidies may be either positive or negative depending on the behavior of the shared consumer. Here we document strong links between riverine insects, riparian lizards (Sceloporus occidentalis), and terrestrial invertebrates. We hypothesized that aquatic insects subsidize riparian lizard populations leading to higher growth rates of these lizards in near-river habitats, and that subsidies exert short-term positive effects on terrestrial resources as a result of diet shifts by lizards to aquatic insects. To test these hypotheses, we used 2 m high fences, or “subsidy shields,” to experimentally reduce aquatic insect flux to large (91 m 2) enclosures of lizards. Subsidy shields reduced aquatic insect flux by 55-65%. Growth rates of lizards were 7X higher in subsidized (no-shield) enclosures during the early summer but were not significantly different later in the summer, when ambient fluxes of aquatic insects dropped to 20% of their early season levels. Within the watershed, lizard growth rates (in mass) were positively correlated with the numerical abundance of aquatic insects. Thus, lizard growth rates tracked both seasonal and spatial availability of riverine insect subsidies during our experiment. Subsidies also had indirect effects on the ground-dwelling, terrestrial prey of lizards. Declines of diurnal terrestrial invertebrates Were significantly higher in shield than no-shield enclosures, and the most common ground spider (Arctosa sp. [Lycosidae]) disappeared completely from shield enclosures by the end of the experiment. Declines in terrestrial invertebrate abundance did not differ between no-shield enclosures and lizard exclosures. These data suggest that riverine insects subsidize riparian Sceloporus and, in the short term, reduce their predation on terrestrial arthropods.
1997
Gresens, Susan E.
Interactive effects of diet and thermal regime on growth of the midge Pseudochironomus richardsoni Malloch Journal Article
In: Freshwater Biology, vol. 38, no. 2, pp. 365-373, 1997, ISSN: 0046-5070.
Abstract | Links | BibTeX | Tags: Blackwater River, diptera, larval chironomidae, rapid growth, Riparian, river food webs, SECONDARY PRODUCTION, size, STREAM, temperature
@article{Gresens1997,
title = {Interactive effects of diet and thermal regime on growth of the midge Pseudochironomus richardsoni Malloch},
author = {Susan E. Gresens},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Gresens_FreshwaterBiology1997.pdf},
doi = {10.1046/j.1365-2427.1997.00248.x},
issn = {0046-5070},
year = {1997},
date = {1997-10-00},
journal = {Freshwater Biology},
volume = {38},
number = {2},
pages = {365-373},
abstract = {1. Larvae of Pseudochironomus richardsoni were reared to pupation in individual enclosures, in one of three thermal habitats in a northern California stream. The average temperature range in cold seeps was 15-21 degrees C, while the main channel ranged from 20 to 27 degrees C, and side pools ranged from 18 to 33 degrees C. Diet consisted of either diatoms or algal detritus.
2. Specific growth rate ranged from 0.057 to 0.267 day(-1). Specific growth and developmental rates were highest on a diatom diet, and increased with temperature. Regressions of growth rate on mean microsite temperature were also significantly altered by diet. Differences in specific growth rate due to diet are magnified at higher temperatures.
3. Pupae reared on diatoms were larger than those reared on detritus. The mass of pupae reared on detritus decreased with increasing temperature. However, there was no significant relationship between pupal mass and temperature for larvae reared on diatoms.
4. The combined effects of food quality and thermal environment on growth of the midge P. richardsoni are significantly different from the independent effects of diet and temperature. Interactive effects of food quality and temperature may influence the contribution of certain aquatic habitats (algal mats) to invertebrate secondary production.},
keywords = {Blackwater River, diptera, larval chironomidae, rapid growth, Riparian, river food webs, SECONDARY PRODUCTION, size, STREAM, temperature},
pubstate = {published},
tppubtype = {article}
}
1. Larvae of Pseudochironomus richardsoni were reared to pupation in individual enclosures, in one of three thermal habitats in a northern California stream. The average temperature range in cold seeps was 15-21 degrees C, while the main channel ranged from 20 to 27 degrees C, and side pools ranged from 18 to 33 degrees C. Diet consisted of either diatoms or algal detritus.
2. Specific growth rate ranged from 0.057 to 0.267 day(-1). Specific growth and developmental rates were highest on a diatom diet, and increased with temperature. Regressions of growth rate on mean microsite temperature were also significantly altered by diet. Differences in specific growth rate due to diet are magnified at higher temperatures.
3. Pupae reared on diatoms were larger than those reared on detritus. The mass of pupae reared on detritus decreased with increasing temperature. However, there was no significant relationship between pupal mass and temperature for larvae reared on diatoms.
4. The combined effects of food quality and thermal environment on growth of the midge P. richardsoni are significantly different from the independent effects of diet and temperature. Interactive effects of food quality and temperature may influence the contribution of certain aquatic habitats (algal mats) to invertebrate secondary production.
2. Specific growth rate ranged from 0.057 to 0.267 day(-1). Specific growth and developmental rates were highest on a diatom diet, and increased with temperature. Regressions of growth rate on mean microsite temperature were also significantly altered by diet. Differences in specific growth rate due to diet are magnified at higher temperatures.
3. Pupae reared on diatoms were larger than those reared on detritus. The mass of pupae reared on detritus decreased with increasing temperature. However, there was no significant relationship between pupal mass and temperature for larvae reared on diatoms.
4. The combined effects of food quality and thermal environment on growth of the midge P. richardsoni are significantly different from the independent effects of diet and temperature. Interactive effects of food quality and temperature may influence the contribution of certain aquatic habitats (algal mats) to invertebrate secondary production.