Stephanie Melles - Academia.edu (original) (raw)

Papers by Stephanie Melles

Limnology and Oceanography Letters

Proceedings of the National Academy of Sciences, 2022

Significance The salinity of freshwater ecosystems is increasing worldwide. Given that most fresh... more Significance The salinity of freshwater ecosystems is increasing worldwide. Given that most freshwater organisms have no recent evolutionary history with high salinity, we expect them to have a low tolerance to elevated salinity caused by road deicing salts, agricultural practices, mining operations, and climate change. Leveraging the results from a network of experiments conducted across North America and Europe, we showed that salt pollution triggers a massive loss of important zooplankton taxa, which led to increased phytoplankton biomass at many study sites. We conclude that current water quality guidelines established by governments in North America and Europe do not adequately protect lake food webs, indicating an immediate need to establish guidelines where they do not exist and to reassess existing guidelines.

Limnology and Oceanography Letters

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Proceedings of the National Academy of Sciences, 2022

Environmental scientists often want to understand how upland features like forest cover affect re... more Environmental scientists often want to understand how upland features like forest cover affect receiving waterbodies (e.g., water quality). Upland areas are characterized by deriving various landscape attributes (e.g., % forest cover in catchment). However, this approach often assumes that the influence of upland features on receiving waterbodies is independent of their proximity to the waterbodies. This may not adequately describe important spatial patterns within the upland area, for example, if there was higher forest cover near the waterbody and lower forest cover farther away. The R statistical software package hydroweight helps to account for these patterns. hydroweight calculates landscape attributes based on distances to waterbodies — areas nearby have more influence than those farther away (i.e., inverse distance-weighting). We implement various scenarios...

Data and analysis code for the paper "Extinction filters mediate the global effects of habit... more Data and analysis code for the paper "Extinction filters mediate the global effects of habitat fragmentation on animals" To run the code for the entire analysis, simply unzip the input folder ("input.zip") and run the script "runner.R" after modifying it to change the working directory. Note - packages listed in this file must be installed beforehand. The analysis scripts read from the provided "input" folder and write to the "output" folder, which is created. Descriptions of variables in the input dataset are provided in "variable descriptions.xlsx".

International Journal of Geographical Information Science, 2018

Citizen science aquatic monitoring programs often rely on opportunistic, incidental contributions... more Citizen science aquatic monitoring programs often rely on opportunistic, incidental contributions, which can lead to spatial bias, the uneven geographical distribution of sample sites. It is less known how this spatial bias compares to professional monitoring activities, or how geospatial biases (e.g. terrain slope, population density, road density) influence aquatic citizen science and professional lake monitoring programs. This paper compares sample sites in Ontario's volunteer Lake Partner Program, against those identified by a stratified random sampling method currently used by the Province of Ontario, Ministry of Natural Resources and Forestry. Exploration of spatial bias within each sampling method was conducted using Kernel Density Estimation, a nonparametric approach to interpolating the spatial trend of a given variable. Results indicate that two distinct patterns of sampling clusters exist between the two datasets, suggesting a 'cottage effect' in which volunteers are more likely to sample accessible locations associated with recreation and summer home ownership. Although professional monitoring programs are not exempt from spatial bias, our research suggests that citizen science lake monitoring programs in Ontario are more influenced by natural and demographic biases related to the location, accessibility, size and general attractiveness of lakes.

This dataset was reformatted from Stephanie J. Melles' (1994) MSc dissertation as part of a L... more This dataset was reformatted from Stephanie J. Melles' (1994) MSc dissertation as part of a Living Data Project internship (https://www.ciee-icee.ca/data.html). Data includes bird abundance and species distribution data, as well as habitat variables at various survey sites in Vancouver, BC.

Global Change Biology, 2010

Species' ranges are dynamic, shifting in response to a large number of interrelated ecological an... more Species' ranges are dynamic, shifting in response to a large number of interrelated ecological and anthropogenic processes. Climate change is thought to be one of the most influential drivers of range shifts, but the effects of other confounded ecological processes are often ignored even though these processes may modify expected range responses to climate change. To determine the relative effects of climate, forest availability, connectivity, and biotic processes such as immigration and establishment, we examine range changes occurring in a species of bird, the Hooded Warbler (Wilsonia citrina). We focus predominantly on the periphery of the species' northern range in Canada but we also examine data from the entire species' range. Nesting records in southern Ontario were obtained from two breeding bird Atlases of Ontario separated by a period of 20 years (1981-1985 and 2001-2005), and the rate of range expansion was estimated by comparing the number of occupied areas in each Atlas. Twelve hypotheses of the relationship between the rate of range expansion and factors known to influence range change were examined using modelselection techniques and a mixed modeling approach (zero-inflated Poisson's regression). Cooler temperatures were positively related to a lack of range expansion indicating that climate constrained the species' distribution. Establishment probability (based on the number of occupied, neighboring Atlas squares) and immigration from populations to the south (estimated using independent data from the North American Breeding Bird Survey) were also important predictors of range expansion. These biotic process variables can mask the effects of forest availability and connectivity on range expansion. Expansion due to climate change may be slower in fragmented systems, but the rate of expansion will be influenced largely by biotic processes such as proximity to neighboring populations.

Spatial Statistics, 2012

This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit:

To assess the relative importance of local- and landscape-level habitat measures in relation to o... more To assess the relative importance of local- and landscape-level habitat measures in relation to observed bird distributions, we used urban gradient analysis to examine the bird community in Vancouver and Burnaby, British Columbia, Canada along four transects. Specifically, we tested the expectation that bird species richness should decline and mean relative abundance of the remaining species should increase with increasing urbanization, as summarized by a habitat gradient. We expected that the surrounding landscape (habitat measures within 0-1000 m) would adequately describe this urbanization gradient and would make better predictors of bird species and nesting guild presence than local-level habitat measures at the residential plot scale (within 50 m). We were also interested in examining whether or not species incidence (the proportion of sites occupied) increased with park proximity, possibly because birds disperse from high-density park areas or because parks contribute critical...

This study presents an innovative approach to the design of a road weather information monitoring... more This study presents an innovative approach to the design of a road weather information monitoring system (RWIS) that optimally combines spatial data on weather-related road surface conditions with data on traffic volume over a state-wide road network. The optimization method minimizes the spatially averaged ordinary kriging variance of hazardous road surface condition (HRSC) frequencies. Since it is desired that an RWIS should also be located at high traffic demand areas, road class data is implemented in the optimization process. Spatial simulated annealing (SSA) is used to search for the optimal RWIS network design by iteratively examining each possible location and accepting designs that ameliorate a weighted sum of average kriging variance and road class detection capability. This novel approach is applied in the optimization of Minnesota RWIS network to illustrate the distinct features of the proposed method, assess the effectiveness of the current location setting, and recomme...

The design of radiation monitoring networks were optimized by combining a geostatistical assessme... more The design of radiation monitoring networks were optimized by combining a geostatistical assessment of routine prediction error with simulation modelling to assess network signalling function in emergency settings. A physical atmospheric dispersion model was used to simulate radioactive releases throughout the study area under different accident scenarios and varying weather conditions (e.g. small nuclear power plant accidents and mock human-caused radioactive emissions). Network signalling function was defined as the ability to detect radioactivity above a critical threshold within 3 hours of a nuclear release. Spatial simulated annealing was used to obtain optimal monitoring designs by moving stations around and accepting those designs that reduced a weighted sum of two criteria (prediction error of mean annual background radiation and network signalling function). Results were promising and the method should prove useful for assessing the efficacy of hazard monitoring networks de...

Mercury pollution is a global environmental problem that threatens ecosystems, and negatively imp... more Mercury pollution is a global environmental problem that threatens ecosystems, and negatively impacts human health and well-being. Mercury accumulation in fish within freshwater lakes is a complex process that appears to be driven by factors such as individual fish biology and water chemistry at the lake-scale, whereas, climate, and land-use/land-cover conditions within lake catchments can be influential at relatively larger scales. Nevertheless, unravelling the intricate network of pathways that govern how lake-scale and large-scale factors interact to affect mercury levels in fish remains an important scientific challenge. Using structural equation models (SEMs) and multiple long-term databases we identified direct and indirect effects of lake-scale and larger-scale factors on mercury levels in Walleye and Northern Pike - two species that are valued in inland fisheries. At the lake-level, the most parsimonious path models contained direct effects of fish weight, DOC, and pH, as we...

To prepare for the unlikely event of a nuclear eme rgency, atmospheric dispersion models are used... more To prepare for the unlikely event of a nuclear eme rgency, atmospheric dispersion models are used to forecast relea s concentrations and radionuclide deposition rates. By combining model pre dictions with spatial analyses of real-time gamma-dose rate measurements at permanent ( n = 153) and mobile device stations ( n = 8), more informed intervention decisions can be considered. The main objective of this research was to determine where to optimally locate mobile measuring dev ic s in order to minimize costs associated with faulty decisions. Incorr ect decisions may be the result of uncertainty in predicting the spread of a potential radioactive plume. Spatial simulated annealing was used to opti mally position mobile devices by minimizing a weighted sum of expected fa lse positive and false negative areas (i.e., false classification into saf e and unsafe zones). Results indicated that the optimal placement of mobile devi c s tended to be in areas at, or just inside, the edge of an a...

The unequal distribution of wealth in cities contributes to other forms of spatial, social, and b... more The unequal distribution of wealth in cities contributes to other forms of spatial, social, and biological inequities in complex, interacting, and self-reinforcing ways. Recent work on urban birds has often focused on community-level correlation studies of short duration in which many points along an urban gradient are surveyed for birds, and the data are related to various ecological variables measured at multiple scales. Spatial variation in urban bird communities may also reflect socioeconomic variables and cultural differences among the human population. The purpose of this paper was to examine whether socioeconomic factors (such as mean family income and ethnic diversity) also relate to the diversity and abundance of birds in Vancouver, British Columbia. I used redundancy analysis to characterize the socioeconomic gradient in a citywide study of the bird community in 44 census-defined neighborhoods. Mean family income, census tract area, and ethnicity were some of the dominant variables that correlated with most of the variation in the bird community. I found no direct relationship between neighborhood age and bird diversity and abundance. Results demonstrate that wealthier neighborhoods have more native species of birds and that these native species increase in abundance as the socioeconomic status of the neighborhood improves. With two-thirds of the world's population expected to live in cities by 2030, more and more people will grow up surrounded by a depauperate community of birds, and this could adversely affect the way people perceive, appreciate, and understand nature. Ultimately, as city birdlife diminishes and urban dwellers become dissociated from the natural diversity it represents, popular support for preserving and restoring such diversity may wane, allowing ecological conditions to further erode.

Scientific Data

Climate change and other anthropogenic stressors have led to long-term changes in the thermal str... more Climate change and other anthropogenic stressors have led to long-term changes in the thermal structure, including surface temperatures, deepwater temperatures, and vertical thermal gradients, in many lakes around the world. Though many studies highlight warming of surface water temperatures in lakes worldwide, less is known about long-term trends in full vertical thermal structure and deepwater temperatures, which have been changing less consistently in both direction and magnitude. Here, we present a globally-expansive data set of summertime in-situ vertical temperature profiles from 153 lakes, with one time series beginning as early as 1894. We also compiled lake geographic, morphometric, and water quality variables that can influence vertical thermal structure through a variety of potential mechanisms in these lakes. These long-term time series of vertical temperature profiles and corresponding lake characteristics serve as valuable data to help understand changes and drivers of...

Scientific Reports

Globally, lake surface water temperatures have warmed rapidly relative to air temperatures, but c... more Globally, lake surface water temperatures have warmed rapidly relative to air temperatures, but changes in deepwater temperatures and vertical thermal structure are still largely unknown. We have compiled the most comprehensive data set to date of long-term (1970–2009) summertime vertical temperature profiles in lakes across the world to examine trends and drivers of whole-lake vertical thermal structure. We found significant increases in surface water temperatures across lakes at an average rate of + 0.37 °C decade−1, comparable to changes reported previously for other lakes, and similarly consistent trends of increasing water column stability (+ 0.08 kg m−3 decade−1). In contrast, however, deepwater temperature trends showed little change on average (+ 0.06 °C decade−1), but had high variability across lakes, with trends in individual lakes ranging from − 0.68 °C decade−1 to + 0.65 °C decade−1. The variability in deepwater temperature trends was not explained by trends in either s...

Journal of Environmental Quality

Limnology and Oceanography Letters

Proceedings of the National Academy of Sciences, 2022

Limnology and Oceanography Letters

Proceedings of the National Academy of Sciences, 2022

International Journal of Geographical Information Science, 2018

Global Change Biology, 2010

Spatial Statistics, 2012

Scientific Data

Scientific Reports

Journal of Environmental Quality