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We present a case-study evaluation of gillnet catches of Walleye Sander vitreus to assess potential effects of large-scale changes in Oneida Lake, New York, including disruption of trophic interactions by double-crested cormorants Phalacrocorax auritus and invasive dreissenid mussels. We used the empirical long-term gillnet time series and a negative binomial linear mixed model to partition variability into spatial and coherent temporal variance components, and we propose that variance partitioning can help quantify spatiotemporal variability and examine if variance structure differs before and after large-scale perturbation. Here, we found that average catch and total variability of catches decreased following...
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Synopsis: This study investigates the relationships of landscape disturbance, altered prey resources, and rattlesnake populations in the Upper Snake River Plain of southeastern. Researchers used radio telemetry to track rattlesnakes while concurrently conducting habitat sampling and small mammal trapping in areas used by snakes and in random locations. Disturbed areas (by grazing and/or burning) were characterized by lower biological crust cover, shrub cover, shrub height, and shrub dispersion, as well as higher grass and bare soil cover. Disturbed areas were also characterized by lower proportions of small animal biomass, abundance, and large prey species (such as chipmunks), while the proportions Conclusions:...
By influencing nutrient mineralization in the soil, decomposers may affect the performance of plants and their associated herbivores. The strength of above–belowground linkages may therefore depend on the availability of nutrients in ecosystems. We investigated the dependency of decomposer- and leaf-herbivore-mediated changes in plant performance on soil nutrient availability in microcosm systems. In separate treatments, Poa annua was used as host plant for the herbivore and was grown in combination with different herb species: Plantago lanceolata, Trifolium repens, and Sanguisorba minor. At three different levels of nutrient availability, the impact of Collembola (Folsomia candida) and aphids (Rhopalosiphum padi),...
Crayfish are not native to the Colorado River basin (CRB), however they are now established in portions of the mainstem and in many tributaries. I used density manipulation experiments in a laboratory setting to determine intra- and interspecific competition for food between Orconectes virilis, an aggressive polytrophic crayfish now common in the CRB, and two native fishes: Gila chub, Gila intermedia, and flannelmouth sucker, Catostomus latipinnis. I tested each fish species in separate trials. Growth of Gila chub decreased when animal densities increased, however they were more affected by intraspecific competition than by crayfish presence. In contrast, growth of flannelmouth suckers was more affected by crayfish...
Spatial patterns of resource use by small-bodied fishes in the San Juan River were examined using stable isotopes. Using δ15N of fishes as an index of trophic position, our data suggest both native and non-native fishes primarily consumed macro-invertebrates. The δ13C of these fishes further suggested a detritus-based food web, from which most species fed on chironomids in low-velocity habitats. A two-way ANOVA revealed a significant interaction between trophic level of fish species and longitudinal position in the river. This interaction was primarily attributed to a decline in trophic level of non-native red shiner Cyprinella lutrensis, relative to other species, in upstream reaches of the river. In addition,...
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Lake Erie Biological Station (LEBS), located in Sandusky, Ohio, is a field station of the USGS Great Lakes Science Center (GLSC). LEBS is the primary federal agency for applied fisheries science excellence in Lake Erie. From 2011-2013, LEBS carried out a project which addressed the effects of regional climate change on aquatic food webs in the Great Lakes. This study focused on Lake Erie, as it is a representative system with a high level of anthropogenic impacts, strong nutrient gradients, seasonal hypoxia, and spatial overlap of cold- and cool-water fish guilds. In Lake Erie and in large embayments throughout the Great Lakes basin, this situation is a concern for fishery managers, as climate change may exacerbate...
By influencing nutrient mineralization in the soil, decomposers may affect the performance of plants and their associated herbivores. The strength of above–belowground linkages may therefore depend on the availability of nutrients in ecosystems. We investigated the dependency of decomposer- and leaf-herbivore-mediated changes in plant performance on soil nutrient availability in microcosm systems. In separate treatments, Poa annua was used as host plant for the herbivore and was grown in combination with different herb species: Plantago lanceolata, Trifolium repens, and Sanguisorba minor. At three different levels of nutrient availability, the impact of Collembola (Folsomia candida) and aphids (Rhopalosiphum padi),...
The consequences of climate change for ecosystem structure and function remain largely unknown. Here, I examine the ability of climate variation to explain long-term changes in bird and plant populations, as well as trophic interactions in a high-elevation riparian system in central Arizona, USA, based on 20 years of study. Abundances of dominant deciduous trees have declined dramatically over the 20 years, correlated with a decline in overwinter snowfall. Snowfall can affect overwinter presence of elk, whose browsing can significantly impact deciduous tree abundance. Thus, climate may affect the plant community indirectly through effects on herbivores, but may also act directly by influencing water availability...
    map background search result map search result map Linking landscape disturbance to the population ecology of Great Basin rattlesnakes (Crotalus oreganus lutosus) in the Upper Snake River Plain A comparison of aquatic trophic interactions (fish, benthic macroinvertebrates, and zooplankton) between the Lake Erie Central Basin and the Lake Erie Eastern Basin, 2011-2013 A comparison of aquatic trophic interactions (fish, benthic macroinvertebrates, and zooplankton) between the Lake Erie Central Basin and the Lake Erie Eastern Basin, 2011-2013 Linking landscape disturbance to the population ecology of Great Basin rattlesnakes (Crotalus oreganus lutosus) in the Upper Snake River Plain