Gavin Leslie Simpson

Gavin Leslie Simpson
Aarhus University | AU · Department of Animal Science

B.Sc. (Hons), Ph.D.

About

421
Publications
126,771
Reads
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24,619
Citations
Introduction
I'm Quantitative Environmental Scientist in the Institute of Environmental Change & Society, & Adjunct Professor, at the University of Regina, Canada. I undertake research on environmental problems, including climate change and atmospheric pollution, affecting lakes. I use lake sediments to look back in time at the history of lakes to look at what organisms are present and how the species in the lake have changed through time and how lakes evolve and respond to pollution and perturbations.
Additional affiliations
March 2013 - present
University of Regina
Position
  • Professor (Associate)
February 2012 - present
University of Regina
Position
  • Quantitative Environmental Scientist
January 2004 - December 2012
University College London
Education
October 1998 - February 2002
University College London
Field of study
  • Geography
October 1995 - June 1998
University College London
Field of study
  • Environmental Geography

Publications

Publications (421)
Article
Full-text available
Common physiological time series and waveforms are composed of repeating cardiac and respiratory cycles. Often, the cardiac effect is the primary interest, but for, e.g., fluid responsiveness prediction, the respiratory effect on arterial blood pressure also convey important information. In either case, it is relevant to disentangle the two effects...
Book
Full-text available
The vegan package provides tools for descriptive community ecology. It has most basic functions of diversity analysis, community ordination and dissimilarity analysis. Most of its multivariate tools can be used for other data types as well. The functions in the vegan package contain tools for diversity analysis, ordination methods and tools for th...
Article
Full-text available
Climate-induced variation in lake level can affect physicochemical properties of endorheic lakes, but its consequences for phototrophic production and regime shifts are not well understood. Here, we quantified changes in the abundance and community composition of phototrophs in Kenosee and White Bear lakes, two endorheic basins in the parkland Moos...
Article
Full-text available
The COVID-19 pandemic prompted a transition to remote delivery of courses that lack immersive hands-on research experiences for undergraduate science students, resulting in a scientific research skills gap. In this report, we present an option for an inclusive and authentic, hands-on research experience that all students can perform off-campus. Bio...
Article
Full-text available
Biological nutrient removal (BNR) may be an effective strategy to reduce eutrophication; however, concerns remain about effects on receiving waters of removing both nitrogen (N) and phosphorus (P), rather than P alone. Phytoplankton abundance (as µg chlorophyll a/L) and community composition (as nmol biomarker pigment/L) were quantified over 6 year...
Article
Full-text available
Pollution with nitrogen (N) and phosphorous (P) impairs streams by favoring suspended algae and cyanobacteria over diatom‐rich periphyton. Recently, wastewater treatment plants have been upgraded to biological nutrient removal to eliminate both P and N (mainly NH4+), although little is known of the effects of this effluent on flowing waters. Here,...
Article
Full-text available
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Article
How Indigenous peoples and European settlers transformed terrestrial ecosystems in the Americas is well evidenced in the literature, but far less is known about how aquatic ecosystems changed. This study examined diatom records from sediment cores from paleoclimate studies in mountain lakes of Guatemala, Panama, and Colombia, in order to clarify th...
Article
Full-text available
Stable isotopes of hydrogen (δ2H) and oxygen (δ18O) provide important quantitative measures of lake hydrology and water balance, particularly in lakes where monitoring of fluxes is incomplete. However, little is known of the relative effects of seasonal variation in water isotopes on estimates of lake hydrology, particularly over decadal scales. To...
Book
Full-text available
The vegan package provides tools for descriptive community ecology. It has most basic functions of diversity analysis, community ordination and dissimilarity analysis. Most of its multivariate tools can be used for other data types as well. # The functions in the vegan package contain tools for diversity analysis, ordination methods and tools for t...
Article
Full-text available
Incidence of elevated harmful algal blooms and concentrations of microcystin are increasing globally as a result of human‐mediated changes in land use and climate. However, few studies document changes in the seasonal and interannual concentrations of microcystin in lakes. Here, we modeled 11 yr of biweekly microcystin data from six lakes to charac...
Article
Full-text available
Human activities alter processes that control local biodiversity, causing changes in the abundance and identity of species in ecosystems. However, restoring biodiversity to a previous state is rarely as simple as reintroducing lost species or restoring processes to their pre-disturbance state. Theory suggests that established species can impede shi...
Article
Full-text available
Small farm reservoirs are abundant in many agricultural regions across the globe and have the potential to be large contributing sources of carbon dioxide (CO2) and methane (CH4) to agricultural landscapes. Compared to natural ponds, these artificial waterbodies remain overlooked in both agricultural greenhouse gas (GHG) inventories and inland wate...
Article
Full-text available
Mass-balance models using stable isotopes of hydrogen and oxygen provide useful estimates of the water balance of lakes, particularly in the absence of instrumental data. However, isotopic mass balances are rarely compared directly to measured water fluxes. Here we compared instrumental and isotope-based determinations of water fluxes in seven conn...
Article
Full-text available
Small farm reservoirs are abundant in many agricultural regions across the globe and have the potential to be large contributing sources of carbon dioxide (CO2) and methane (CH4) to agricultural landscapes. Compared to natural ponds, these artificial waterbodies remain overlooked in both agricultural greenhouse gas (GHG) inventories and inland wate...
Preprint
Full-text available
Converting habitat for agricultural production threatens biodiversity loss worldwide and has significant implications for human well-being. Debates on how to conserve biodiversity as the demand for agriculture products rises is being informed by studies using habitat specificity as a proxy for sensitivity to land modification, assuming all species...
Article
Full-text available
In this paper, we discuss an extension to two popular approaches to modeling complex structures in ecological data: the generalized additive model (GAM) and the hierarchical model (HGLM). The hierarchical GAM (HGAM), allows modeling of nonlinear functional relationships between covariates and outcomes where the shape of the function itself varies b...
Article
Full-text available
Nitrogen pollution and global eutrophication are predicted to increase nitrous oxide (N 2 O) emissions from freshwater ecosystems. Surface waters within agricultural landscapes experience the full impact of these pressures and can contribute substantially to total landscape N 2 O emissions. However, N 2 O measurements to date have focused on flowin...
Article
Full-text available
Cultivation of dedicated soil plots called ‘landfarms' is an effective technology for bioremediation of hydrocarbon waste generated by various industrial practices. To understand the influence of soil conditions on landfarm microbial communities, analysis of bacterial and fungal community structure using next‐generation sequencing at different sect...
Article
Carbon and nitrogen stable isotope ratios of sub-fossil invertebrate remains are potentially powerful indicators of nutrient flux, habitat-specific resource utilization, and trophic interactions in lentic food webs, but are rarely estimated for multiple species within lakes. Here we examined historical time series of δ 13 C and δ 15 N in remains of...
Article
Full-text available
The La Niña and El Niño phases of the El Niño-Southern Oscillation (ENSO) have major impacts on regional rainfall patterns around the globe, with substantial environmental, societal and economic implications. Long-term perspectives on ENSO behaviour, under changing background conditions, are essential to anticipating how ENSO phases may respond und...
Article
Full-text available
Biogeochemical processes are active year‐round in ice‐covered lakes, such that processes in one season can affect limnological conditions in subsequent seasons. However, the extent and nature of these legacy effects are poorly understood, particularly for the CO2 content of lakes and when considering gas exchange with the atmosphere. Here, we used...
Preprint
Full-text available
Human activities alter processes that control local biodiversity, causing changes in the abundance and identity of species in many ecosystems. However, restoring biodiversity to a previous state is rarely as simple as reintroducing lost species or restoring processes to their pre-disturbance state. Theory suggests that established species can imped...
Article
Full-text available
Previous research suggests that fertilization of surface waters with chemically reduced nitrogen (N), including ammonium (NH4+), may either enhance or suppress phytoplankton growth. To identify the factors influencing the net effect of NH4+, we fertilized natural phytoplankton assemblages from two eutrophic hardwater lakes with growth‐saturating co...
Article
Full-text available
Context/Objectives: Spinal cord injury (SCI) results in significant neuronal and glial cell death resulting in impaired neurological and motor function. Uncontrolled Ca²⁺ entry results in excitotoxicity and cell death. In this study, we examine the use of a BK channel activator, Isopimaric acid (ISO), as a neuroprotective agent post-SCI as this cha...
Preprint
Full-text available
In this paper, we discuss an extension to two popular approaches to modelling complex structures in ecological data: the generalized additive model (GAM) and the hierarchical model (HGLM). The hierarchical GAM (HGAM), allows modelling of nonlinear functional relationships between covariates and outcomes where the shape of the function itself varies...
Preprint
Full-text available
In this paper, we discuss an extension to two popular approaches to modelling complex structures in ecological data: the generalized additive model (GAM) and the hierarchical model (HGLM). The hierarchical GAM (HGAM), allows modelling of nonlinear functional relationships between covariates and outcomes where the shape of the function itself varies...
Article
Full-text available
• Limnological theory posits that phosphorus (P) limits primary production in freshwater lakes, in part because fixation of atmospheric nitrogen (N2) can compensate for limitations in nitrogen (N) supply to phytoplankton. However, quantitative estimates of the degree to which N2 fixation satisfies planktonic N demand are rare. • Here we used biweek...
Article
Full-text available
In the absence of annual laminations, time series generated from lake sediments or other similar stratigraphic sequences are irregularly spaced in time, which complicates formal analysis using classical statistical time series models. In lieu, statistical analyses of trends in palaeoenvironmental time series, if done at all, have typically used sim...
Conference Paper
Full-text available
Carbon fluxes from aquatic environments have proven to be globally significant in offsetting terrestrial carbon uptake. At the catchment scale, aquatic pathways can contribute 1 to 300 gCm-2yr-1 to ecosystem carbon budgets, representing a large range in terrestrial carbon offsets (<1% to 500% of terrestrial production). However, existing studies th...
Article
Spatiotemporal variation in climate and weather, allochthonous carbon loads, and autochthonous factors such as lake metabolism (photosynthesis and respiration) interacts to regulate atmospheric CO2 exchange of lakes. Understanding this interplay in diverse basin types at different timescales is required to adequately place lakes into the global car...
Preprint
Full-text available
In the absence of annual laminations, time series generated from lake sediments or other similar stratigraphic sequences are irregularly spaced in time, which complicates formal analysis using classical statistical time series models. In lieu, statistical analyses of trends in palaeoenvironmental time series, if done at all, have typically used sim...
Article
Full-text available
Disruption of the nitrogen cycle is a major component of global environmental change. d15N in lake sediments is increasingly used as a measure of reactive nitrogen input but problematically, the characteristic depleted d15N signal is not recorded at all sites. We used a regionally replicated sampling strategy along a precipitation and N-deposition...
Book
Full-text available
The vegan package provides tools for descriptive community ecology. It has most basic functions of diversity analysis, community ordination and dissimilarity analysis. Most of its multivariate tools can be used for other data types as well. The functions in the vegan package contain tools for diversity analysis, ordination methods and tools for th...
Article
Background: Cytomegalovirus (CMV) infection is implicated in endothelial dysfunction and graft damage after pediatric heart transplantation. CMV specific immune responses are thought to be necessary for CMV viral control but there is little data in pediatric heart transplantation. Methods: We studied 28 consecutive pediatric heart transplant rec...
Article
Critical transitions in ecosystem states are often sudden and unpredictable. Consequently, there is a concerted effort to identify measurable early warning signals (EWS) for these important events. Aquatic ecosystems provide an opportunity to observe critical transitions due to their high sensitivity and rapid response times. Using palaeoecological...
Article
Full-text available
The relative roles of anthropogenic nitrogen (N) deposition and climate change in causing ecological change in remote Arctic ecosystems, especially lakes, have been the subject of debate over the last decade. Some palaeoecological studies have cited isotopic signals (δ(¹⁵N)) preserved in lake sediments as evidence linking N deposition with ecologic...
Article
Full-text available
Hardwater lakes are common in human-dominated regions of the world and often experience pollution due to agricultural and urban effluent inputs of inorganic and organic nitrogen (N). Although these lakes are landscape hotspots for CO2 exchange and food web carbon (C) cycling, the effect of N enrichment on hardwater lake food web functioning and C c...
Data
Statistical results for temporal patterns in mesocosm plankton dynamics and C cycling. Repeated -measures analysis of variance (RM-ANOVA) of the effects of urea amendments (0, 1, 3, 8, or 18 mg N L-1 week-1) on variables related to biological production. Tukey’s HSD post hoc analyses indicate differences among treatments, and given probability leve...
Data
Hypothetical mechanism by which addition of urea stimulates heterotrophic microbial production. (DOCX)
Data
Map of Wascana Lake and experiment location. a) continental location, b) gross drainage basin (1400 km2) and lake location, and c) depth contour map with the location of the mesocosm experiment (hatched area) and two long term monitoring sites (x). (TIF)
Data
Temporal patterns in mesocosm plankton dynamics. Effects of urea on (a) phytoplankton abundance (Chl a), (b) gross primary production (GPP), (c) bacterial density, (d) bacterial C consumption (BCC; production + respiration), (e) GPP:BCC, and (f) dissolved oxygen concentration (DO). Experimental enclosures received urea amendments of 0 (black circle...
Data
Temporal patterns in mesocosm limnological conditions. Limnological conditions during July, August, and September mesocosm experiments including concentrations of (a) total dissolved nitrogen (TDN), (b) total dissolved (TDP), (c) soluble reactive phosphorus (SRP), (d) dissolved organic carbon (DOC), (e) water transparency as Secchi disk depth, and...
Data
Temporal patterns in mesocosm inorganic carbon dynamics. Effects of urea on (a) pH, (b) dissolved inorganic carbon concentration (DIC), (c) partial pressure of CO2 in the water column (pCO2; dashed line indicates equilibrium with the atmosphere), and (d) net air-water CO2 flux (positive values above dashed line represent influx). Experimental enclo...
Data
Statistical results for temporal patterns in mesocosm limnological conditions. Repeated-measures analysis of variance (RM-ANOVA) of the effects of urea amendment (0, 1, 3, 8, or 18 mg N L-1 week-1) on limnological conditions in mesocosms. Tukey’s HSD post hoc analyses indicate differences among treatments, and given probability levels (P) are prese...
Data
Data underlying experimental analyses. (XLSX)
Conference Paper
Full-text available
Ponds and small lakes are known to be hotspots for carbon and nutrient cycling in landscapes, but are currently underappreciated in global inland water cycles. Such water bodies are particularly important in agricultural landscapes as they receive, store and process large quantities of organic matter and nutrients which would otherwise enter downst...
Article
Full-text available
Several limnological and paleolimnological investigations have linked enhanced atmospheric nitrogen (N) deposition to nutrient enrichment and increased primary production. The Athabasca Oil Sands Region (AOSR) in northeast Alberta, Canada is a significant source of N emissions, particularly since development intensified during the 1990s, and recent...
Book
Full-text available
The vegan package provides tools for descriptive community ecology. It has most basic functions of diversity analysis, community ordination and dissimilarity analysis. Most of its multivariate tools can be used for other data types as well. The functions in the vegan package contain tools for diversity analysis, ordination methods and tools for th...
Article
Full-text available
Snowpack chemistry, nitrate stable isotopes and net deposition fluxes for the largest ice-free region in Greenland were investigated to determine whether there are spatial gradients from the ice sheet margin to the coast linked to a gradient in precipitation. Late-season snowpack was sampled in March 2011 at 8 locations within 3 lake catchments in...
Article
Full-text available
As the industrial footprint of the Athabasca Oil Sands Region (AOSR) continues to expand, concern about the potential impacts of pollutants on the surrounding terrestrial and aquatic ecosystems need to be assessed. An emerging issue is whether recent increases in lake production downwind of the development can be linked to AOSR activities, and/or w...
Book
Full-text available
The vegan package provides tools for descriptive community ecology. It has most basic functions of diversity analysis, community ordination and dissimilarity analysis. Most of its multivariate tools can be used for other data types as well. The functions in the vegan package contain tools for diversity analysis, ordination methods and tools for th...
Book
Full-text available
The vegan package provides tools for descriptive community ecology. It has most basic functions of diversity analysis, community ordination and dissimilarity analysis. Most of its multivariate tools can be used for other data types as well. The functions in the vegan package contain tools for diversity analysis, ordination methods and tools for th...
Article
Full-text available
Lake Whitefish Coregonus clupeaformis is the most commercially valuable species in Lake Huron. The fishery for this species has historically been managed based on 25 management units (17 in Canada, 8 in the USA). However, congruence between the contemporary population structure of Lake Whitefish and management units is poorly understood. We used st...