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We propose a framework for hypothesis-testing of stable isotope ratios in ecological studies. Statistical procedures are based on analysis of nested linear models and a residual permutation procedure (RPP) that is employed to evaluate probabilities associated with test statistics. We used simulated examples and a real data set to illustrate the utility and generality of the method. First, we developed a test for differences in centroid location and dispersion of delta13C and delta15N values within and among groups of isotopic data. Second, we evaluated magnitude and direction of change in centroid position (termed "path") of a pair of isotopic samples separated in space/time relative to paths of other paired sample...
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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In 2014, the USGS Lake Erie Biological Station participated in the Coordinated Science and Monitoring Initiative (CMSI) program, a program founded by the U.S. Environmental Protection Agency (EPA) and Environment Canada in the 1990s as a means to focus collaborative research attention on one of the five Great Lakes each year (on a rotating schedule) as a means to increase scientific knowledge for Great Lakes restoration. The Lake Erie survey examined the food web across a nearshore to offshore gradient, matching the sampling design the preceding USGS studies of the other four Great Lakes (2010-2013). We sampled all trophic levels in all three lake basins across multiple seasons in order to determine nutrient availability...
In many ecosystems, seasonal shifts in temperature and precipitation induce pulses of primary productivity that vary in phenology, abundance, and nutritional quality. Variation in these resource pulses could strongly influence community composition and ecosystem function, because these pervasive bottom-up forces play a primary role in determining the biomass, life cycles, and interactions of organisms across trophic levels. The focus of this research is to understand how consumers across trophic levels alter resource use and assimilation over seasonal and interannual timescales in response to climatically driven changes in pulses of primary productivity. We measured the carbon isotope ratios (delta(13)C) of plant,...
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The Great Lakes Research Vessel Operations data release is taken from the Research Vessel Catch (RVCAT) database curated at the Great Lakes Science Center (GLSC). RVCAT has been used as the primary data collection tool aboard the GLSC’s research vessel operations. Content: The data set has been collected on various vessel operations on all the Great Lakes and select connecting waterways between the years 1958-2018. Data collection begins in early spring and ends in late fall. Each vessel operation was completed for a specific purpose, or target mission, which are enumerated in this data set. In addition to vessel operations data, RVCAT collects trawl and gillnet catch data, sample information of fish species caught,...
Types: Citation; Tags: Alewife, Bathythermograph, Benthos, Bloater, Cisco, All tags...
The main route of exposure for selenium (Se) is dietary, yet regulations lack biologically based protocols for evaluations of risk. We propose here an ecosystem-scale model that conceptualizes and quantifies the variables that determine how Se is processed from water through diet to predators. This approach uses biogeochemical and physiological factors from laboratory and field studies and considers loading, speciation, transformation to particulate material, bioavailability, bioaccumulation in invertebrates, and trophic transfer to predators. Validation of the model is through data sets from 29 historic and recent field case studies of Se-exposed sites. The model links Se concentrations across media (water, particulate,...
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Diet contents of Deepwater Sculpin (Myoxocephalus thompsonii) were identified, enumerated, and measured to monitor the changes in the offshore benthic fish community within Lake Huron. Collections were made using a 21-m headrope with a 4.76mm square mesh cod-end with 10 minute contour trawl tows.. Deepwater Sculpin collected from the USGS fall forage (2003-2005 and 2010-2014) were counted and weighed en masse on board research vessel. Individual weights (nearest 0.001g) and measurements (0.1mm) were conducted in laboratory setting. Stomachs were extracted in laboratory setting (from esophogus to pyloric ceaca). Stomachs were stored in ethanol for later dissection. Stomach contents were removed in petri dish. All...
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These data were compiled for a manuscript that examines the riverine food-web structure of the Colorado River below Glen Canyon dam to its confluence with Lake Mead. Tissue from primary producers (vascular plants and algae) and consumers (aquatic invertebrates and fish) were collected before and after monsoon floods in 2006 along the 388 kilometer segment of the Colorado River in the Southwest US. Tissue samples were dried, ground, and analyzed for δ13C, δ15N, and δ2H stable isotope signatures and percent carbon and nitrogen. Analysis of these data focused on determining the proportion of terrestrial (allochthonous) vs. aquatic (autochthonous) organic matter sources at the base of the food web, trophic diversity...
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This tabular data set contains information about the diets of double-crested cormorants (Phalacrocorax auritus) collected from Saginaw Bay, Lake Huron during April-September 2013 and 2014. Diet items were identified, enumerated, and measured.
The main route of exposure for selenium (Se) is dietary, yet regulations lack biologically based protocols for evaluations of risk. We propose here an ecosystem-scale model that conceptualizes and quantifies the variables that determine how Se is processed from water through diet to predators. This approach uses biogeochemical and physiological factors from laboratory and field studies and considers loading, speciation, transformation to particulate material, bioavailability, bioaccumulation in invertebrates, and trophic transfer to predators. Validation of the model is through data sets from 29 historic and recent field case studies of Se-exposed sites. The model links Se concentrations across media (water, particulate,...
Understanding how communities respond to changes in temperature is a major challenge for community ecology. Temperature influences the relative degree to which top-down and bottom-up forces structure ecological communities. In greenhouse experiments using the aquatic community found in pitcher plants (Sarracenia purpurea), I tested how temperature affected the relative importance of top-down (mosquito predation) and bottom-up (ant carcasses) forces on protozoa and bacteria populations. While bottom-up effects did not vary consistently with temperature, the top-down effects of predators on protozoa increased at higher temperatures. These results suggest that temperature could change the relative importance of top-down...
    map background search result map search result map Great Lakes Research Vessel Operations 1958-2018. (ver. 3.0, April 2019) Double-crested Cormorant Diet Composition from Two Colonies in Saginaw Bay, Lake Huron, 2013-2014 Diets of Deepwater Sculpin collected from fall forage (2003-05 and 2010-14) in Lake Huron Food Web Data, Colorado River Corridor, Grand Canyon, Arizona, 2006 Lake Erie Collaborative Science and Monitoring Initiative 2014 Double-crested Cormorant Diet Composition from Two Colonies in Saginaw Bay, Lake Huron, 2013-2014 Food Web Data, Colorado River Corridor, Grand Canyon, Arizona, 2006 Diets of Deepwater Sculpin collected from fall forage (2003-05 and 2010-14) in Lake Huron Lake Erie Collaborative Science and Monitoring Initiative 2014 Great Lakes Research Vessel Operations 1958-2018. (ver. 3.0, April 2019)