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Milas A.S.,Bowling Green State University | Arend K.,Old Woman Creek National Estuarine Research Reserve | Mayer C.,University of Toledo | Simonson M.A.,University of Toledo | Mackey S.,Office of Coastal Management
International Journal of Remote Sensing | Year: 2017

Due to their low light conditions, shadows reduce the accuracy of feature extraction and change detection in remote-sensing images. Unmanned aerial vehicles (UAVs) are capable of acquiring images that have a resolution of several centimetres and removing shadows is a challenge. In this study, the Maximum Likelihood (ML) and Support Vector Machine (SVM) classifiers were used to classify a UAV image acquired using a red–green–blue (RGB) camera over the Old Woman Creek National Estuarine Research Reserve in Ohio, USA. The impact of shadows on the classification process was explored for different pixel sizes ranging from 0.03 to 1.00 m. The SVM generated higher overall accuracy (OA) at finer spatial resolution (0.25–0.50 m), while the optimal spatial resolution for the ML classifier was 1.00 m. The percentage of shadow coverage increased with spatial resolution for both classifiers (1.71% for ML and 6.63% for SVM). Shadows were detected and extracted using two approaches: (a) as a separate class using regions of interests (ROIs) observed in the image, and (b) by applying a segmentation threshold of 0.3 to visible atmospherically resistant index (VARI). The extracted shadows were separately classified using ROIs selected from shaded surfaces, and then removed using the fusion of RGB reflectance, VARI, and digital surface model (DSM) images. The OA of classified shadows reached 91.50%. OAs of merged sunlit and shadow classified images improved for 18.48% for SVM, and 17.62% for the ML classifier. VARI accurately captures shadows, and when fused with RGB reflectance and DSM, it intensifies their low signal and enhances classification. Whether used to capture or to remove shadows, VARI serves as an effective ‘shadow index’. Shadows create obstacles to remote-sensing processing; however, their spectral information should not be neglected as both shadows and sunlit areas are important for ecological processes such as photosynthesis, carbon balance, evapotranspiration, fish abundance, and more. © 2017 Informa UK Limited, trading as Taylor & Francis Group


Scavia D.,University of Michigan | David Allan J.,University of Michigan | Arend K.K.,Old Woman Creek National Estuarine Research Reserve | Bartell S.,ENTRIX Inc. | And 24 more authors.
Journal of Great Lakes Research | Year: 2014

Relieving phosphorus loading is a key management tool for controlling Lake Erie eutrophication. During the 1960s and 1970s, increased phosphorus inputs degraded water quality and reduced central basin hypolimnetic oxygen levels which, in turn, eliminated thermal habitat vital to cold-water organisms and contributed to the extirpation of important benthic macroinvertebrate prey species for fishes. In response to load reductions initiated in 1972, Lake Erie responded quickly with reduced water-column phosphorus concentrations, phytoplankton biomass, and bottom-water hypoxia (dissolved oxygen <2mg/l). Since the mid-1990s, cyanobacteria blooms increased and extensive hypoxia and benthic algae returned. We synthesize recent research leading to guidance for addressing this re-eutrophication, with particular emphasis on central basin hypoxia. We document recent trends in key eutrophication-related properties, assess their likely ecological impacts, and develop load response curves to guide revised hypoxia-based loading targets called for in the 2012 Great Lakes Water Quality Agreement. Reducing central basin hypoxic area to levels observed in the early 1990s (ca. 2000km2) requires cutting total phosphorus loads by 46% from the 2003-2011 average or reducing dissolved reactive phosphorus loads by 78% from the 2005-2011 average. Reductions to these levels are also protective of fish habitat. We provide potential approaches for achieving those new loading targets, and suggest that recent load reduction recommendations focused on western basin cyanobacteria blooms may not be sufficient to reduce central basin hypoxia to 2000km2. © 2014 Elsevier B.V.


Back C.L.,Ohio State University | Back C.L.,The McGraw Hill Co. | Holomuzki J.R.,Ohio State University | Klarer D.M.,Old Woman Creek National Estuarine Research Reserve | Whyte R.S.,California University of Pennsylvania
Wetlands Ecology and Management | Year: 2012

Invasive common reed (Phragmitesaustralis) can rapidly form expansive, near-monotypic stands, and thereby lower plant diversity and change marsh habitat structure. Consequently, North American wetland managers often use herbicides, such as glyphosate-based AquaNeat ® and imazypr-based Habitat ®, to control its establishment and spread. However, herbiciding might indirectly affect benthic community structure by directly altering habitat structure, and habitat alterations may vary with herbicide and concentration. These effects may be particularly pronounced ≥1 year post-herbiciding when dead above-ground biomass collapses and submerges. To evaluate how herbicide-caused alterations in habitat affect key trophic linkages, we compared snail and epiphytic algal assemblages, and habitat conditions, among 20- × 20-m replicated plots of reed treated with either AquaNeat ® (30 % solution), Habitat ® (5 % solution), or left herbicide-free (i. e., controls) in an eutrophic Lake Erie coastal marsh 1-y post-herbiciding. Both herbicides equally reduced reed above-ground growth by >90 % relative to controls. Fossaria spp. and Gyraulus parvus snails were more abundant in herbicide-treated plots than in controls, but Shannon-Wiener diversity was similar (H′ ≈ 1. 0) across treatments. All snails collected were pulmonates, suggesting habitat drying might be driving assemblage structure. Snails were denser in plots with metaphyton (mostly Spirogyra) than without, and metaphyton was more abundant in herbicide-treated plots with higher incident light levels and warmer water temperatures than in controls. Snail biomass was positively related to amount of benthic macro-organic matter but not epiphytic algal biomass, which was similar among treatments. Diatoms dominated algal communities in all treatments. In June, Navicula spp. was dominant in controls, whereas Nitzschia palea and Aulacoseira italic, and Nitzschia spp., were dominant in AquaNeat ® and Habitat ® treatments, respectively. However, algal and diatom assemblages were similar in treatments by early-July when marsh water levels significantly decreased and nitrate levels were <1 μg/L. Marsh hydrologic patterns may mediate herbiciding's indirect effects on trophic structure. © 2012 Springer Science+Business Media B.V.


Millie D.F.,Florida Fish And Wildlife Conservation Commission | Fahnenstiel G.L.,National Oceanic and Atmospheric Administration | Weckman G.R.,Ohio University | Klarer D.M.,Old Woman Creek National Estuarine Research Reserve | And 3 more authors.
Journal of Phycology | Year: 2011

Phytoplankton and Microcystis aeruginosa (Kütz.) Kütz. biovolumes were characterized and modeled, respectively, with regard to hydrological and meteorological variables during zebra mussel invasion in Saginaw Bay (1990-1996). Total phytoplankton and Microcystis biomass within the inner bay were one and one-half and six times greater, respectively, than those of the outer bay. Following mussel invasion, mean total biomass in the inner bay decreased 84% but then returned to its approximate initial value. Microcystis was not present in the bay during 1990 and 1991 and thereafter occurred at/in 52% of sample sites/dates with the greatest biomass occurring in 1994-1996 and within months having water temperatures >19°C. With an overall relative biomass of 0.03±0.01 (mean+SE), Microcystis had, at best, a marginal impact upon holistic compositional dynamics. Dynamics of the centric diatom Cyclotella ocellata Pant. and large pennate diatoms dominated compositional dissimilarities both inter- and intra-annually. The environmental variables that corresponded with phytoplankton distributions were similar for the inner and outer bays, and together identified physical forcing and biotic utilization of nutrients as determinants of system-level biomass patterns. Nonparametric models explained 70%-85% of the variability in Microcystis biovolumes and identified maximal biomass to occur at total phosphorus (TP) concentrations ranging from 40 to 45μg·L -1. From isometric projections depicting modeled Microcystis/environmental interactions, a TP concentration of <30μg·L -1 was identified as a desirable contemporary "target" for management efforts to ameliorate bloom potentials throughout mussel-impacted bay waters. © 2011 Phycological Society of America.


Holomuzki J.R.,Ohio State University | Klarer D.M.,Old Woman Creek National Estuarine Research Reserve
Wetlands Ecology and Management | Year: 2010

We examined how dominance (% canopy cover) and invasion history of common reed, Phragmites australis, affected benthic macroinvertebrate diversity and density in 8 marshes along Lake Erie's southern shoreline. We also compared macroinvertebrate densities among patches (0.25 m2) of reed, cattail (Typha spp.), and native flora (e. g., Sagittaria, Sparganium) and epiphytic algal communities on submerged stems of reed and cattail. Narrow-leaf cattail (T. angustifolia) is also a common invasive plant to these wetlands, but does not greatly change plant community composition or ecosystem conditions like reed. Macroinvertebrate diversity (Shannon-Weaver H′) was positively related to reed cover and was highest (4.6) in two marshes with ~35- and 5-year invasion histories. Shading from high reed cover increased H′-diversity, in part, by reducing the abundance of floating duckweed, which harbored many Hyalella azteca amphipods. Percent Ephemeroptera, Odonata, and Trichoptera was low to moderate across marshes, regardless of reed cover and invasion history. Macroinvertebrate density was not affected by reed cover or average plant stem density, and did not differ among plant types. However, epiphyton densities and % diatoms were greater on reed than on cattail, suggesting reed provides a better feeding habitat for microalgal grazers than Typha. Abundance rankings of common species in these diatom-dominated communities were also typically dissimilar between these plant types. Although % grazers was unrelated to epiphyton densities and % diatoms, grazer identity (snails) differed between natural and diked marshes, which had different microalgal food supplies. Our findings suggest that Phragmites does not necessarily adversely affect macroinvertebrate community structure and diversity and that invasion history alone has little effect on the H′-diversity-reed dominance relationship. © Springer Science+Business Media B.V. 2009.


DeVanna Fussell K.M.,Ohio State University | Smith R.E.H.,University of Waterloo | Fraker M.E.,Ohio State University | Boegman L.,Queen's University | And 16 more authors.
Journal of Great Lakes Research | Year: 2016

The Great Lakes Fishery Commission sponsored a 2-day workshop that sought to enhance the ability of Great Lakes agencies to understand, predict, and ideally manage fisheries production in the face of changes in natural and anthropogenic forcings (e.g., climate, invasive species, and nutrients). The workshop brought together 18 marine and freshwater researchers with collective expertise in aquatic ecology, physical oceanography, limnology, climate modeling, and ecosystem modeling, and two individuals with fisheries management expertise. We report on the outcome of a writing exercise undertaken as part of this workshop that challenged each participant to identify three needs, which if addressed, could most improve the ability of Great Lakes agencies to manage their fisheries in the face of ecosystem change. Participant responses fell into two categories. The first identified gaps in ecological understanding, including how physical and biological processes can regulate early life growth and survival, how life-history strategies vary across species and within populations, and how anthropogenic stressors (e.g., nutrient runoff, climate change) can interact to influence fish populations. The second category pointed to the need for improved approaches to research (e.g., meta-analytic, comparative, spatial translation) and management (e.g., mechanistic management models, consideration of multi-stock management), and also identified the need for improved predictive models of the physical environment and associated ecosystem monitoring programs. While some progress has been made toward addressing these needs, we believe that a continued focus will be necessary to enable optimal fisheries management responses to forthcoming ecosystem change. © 2016.


Young W.A.,Ohio University | Millie D.F.,University of South Florida | Weckman G.R.,Ohio University | Anderson J.S.,Ohio University | And 2 more authors.
Environmental Modelling and Software | Year: 2011

Artificial neural networks (ANNs) and Bayesian belief networks (BBNs) utilizing select environmental variables were developed and evaluated, with the intent to model net ecosystem metabolism (a proxy for system trophic state) within a freshwater wetland. Network modeling was completed independently for distinct data subsets, representing periods of 'low' and 'high' water levels throughout in the wetland. ANNs and BBNs were 'benchmarked' against traditional parametric analyses, with network architectures outperforming regression models. ANNs delivered the greatest predictive accuracy for NEM and did not require expert knowledge about system variables for their development. BBNs provided users with an interactive diagram depicting predictor interaction and the qualitative/quantitative effects of variable dynamics upon NEM, thereby affording better information extraction. Importantly, BBNs accommodated the imbalanced nature of the dataset and appeared less affected (than ANNs) with variable auto-correlation traits that are typically observed within large and 'noisy' environmental datasets. © 2011 Elsevier Ltd.


Whyte R.S.,California University of Pennsylvania | Bocetti C.I.,California University of Pennsylvania | Klarer D.M.,Old Woman Creek National Estuarine Research Reserve
Natural Areas Journal | Year: 2015

A decline in Lake Erie water levels in 2000 from historic high levels of the 1990s has facilitated a shift in coastal wetland vegetation from open-water floating-leaf plant communities to emergent communities often dominated by the invasive perennial grass, Phragmites australis. Dense, near monotypic stands of this grass may lead to the loss of native plants and reduce suitable habitat for waterfowl and other wetland birds. To assess avian response to this shift in plant community structure, we conducted bird surveys (June-August, 2007) across four vegetation types in two coastal wetlands in the western basin of Lake Erie. Phragmites habitat had higher overall bird abundance but contained the lowest species diversity (H' = 0.71) of the four habitat types. Of the 35 species observed across habitat types, 4 species: (1) red-winged blackbird (Agelaius phoeniceus); (2) tree swallow (Tachycineta bicolor); (3) barn swallow (Hirundo rustica); and (4) bank swallow (Riparia riparia), accounted for 94% of total bird abundance. Ninety-four percent of all birds observed in sampled plots of Phragmites were red-winged blackbirds, and 73% of the total bird abundance (all species) across habitats occurred in Phragmites. This was mostly attributed to the large roosts (>500 birds/50-m radius plot) of red-winged blackbirds in sampled plots of Phragmites. Phragmites community overlap (Ro), represented by Horn's index, varied from a low of 0.30 with floating-leaved vegetation to a high of 0.69 within the Typha (cattail) community. Our results suggest that Phragmites does influence bird abundance and species diversity, but caution is warranted without additional data on nest success and survival.

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