Biology subjects

Rooney, R. C.

Publications and source records attributed to Rooney, R. C..

8 recordsLinked to original sources

bioRxiv2025

High co-occurrence of invasive wetland plants and species at risk in Canada's biodiverse Carolinian

Invasive species are a major driver of biodiversity loss, with invasive plants increasingly threatening wetland ecosystems. Southern Ontarios Carolinian Zone, a biodiversity hotspot supporting 79% of Ontarios non-fish Species at Risk (SAR), is especially vulnerable. Over half (54%) of these SAR rely on wetland or semiaquatic habitats, emphasizing the importance of wetland protection for their recovery. These habitats are fragmented and highly susceptible to plant invasions. To guide conservation, we conducted a spatial co-occurrence analysis of non-fish SAR dependent on wetlands and invasive wetland plant species. We identified 33 invasive species posing current (n = 26) or imminent (n = 7) threats in the Carolinian Zone. Overlap between SAR and invasive plants was greatest in Lake Eries coastal marshes and shallow waters, where invasions are well documented, and also in urban areas such as Toronto, Windsor, London, and Niagara, where SAR richness was unexpectedly high. Co-occurrence of SAR and invasive plants in these regions indicates that managing invasive plants in urban wetlands could directly support SAR recovery. Marsh-nesting birds, reptiles, and wetland plants were most exposed and vulnerable to habitat alteration and resource competition. Spatial analyses help pinpoint where invasive plants most threaten SAR, enabling targeted, effective management.

ecology↗

bioRxiv2023

Urban-use pesticides in stormwater ponds and their accumulation in biofilms

Stormwater ponds frequently receive urban runoff, increasing the likelihood of pesticide contamination. Biofilms growing in surface waters of these ponds are known to accumulate a range of aquatic contaminants, paradoxically providing both water purification services and potentially posing a threat to urban wildlife. Thus, sampling biofilms in stormwater ponds may be a critical and biologically relevant tool for characterizing pesticide contamination and toxicity in urban environments. Here, we aimed to investigate pesticide occurrences at 21 stormwater ponds in Brampton, ON, one of Canadas fastest growing municipalities, and quantify their accumulation in biofilm. Over nine weeks, we collected time-integrated composite water and biofilm samples for analysis of [~]500 current-use and legacy pesticides. Thirty-two pesticide compounds were detected across both matrices, with 2,4-D, MCPA, MCPP, azoxystrobin, bentazon, triclopyr, and diuron having near-ubiquitous occurrences. Several compounds not typically monitored in pesticide suites (e.g., melamine and nicotine) were also detected, but only in biofilms. Overall, 56% of analytes detected in biofilms were not found in water samples, indicating traditional pesticide monitoring practices fail to capture all exposure routes, as even when pesticides are below detection levels in water, organisms may still be exposed via dietary pathways. Calculated bioconcentration factors ranged from 4.2 - 1275 and were not predicted by standard pesticide physicochemical properties. Monitoring biofilms provides a sensitive and comprehensive supplement to water sampling for pesticide quantification in urban areas, and identifying pesticide occurrences in stormwater could improve source-tracking efforts in the future. Further research is needed to understand the mechanisms driving pesticide accumulation, to investigate toxicity risks associated with pesticide-contaminated biofilm, and to evaluate whether pesticide accumulation in stormwater pond biofilms represents a route through which contaminants are mobilized into the surrounding terrestrial and downstream aquatic environments.

ecology↗

bioRxiv2021

Control of invasive Phragmites australis (European common reed) alters macroinvertebrate communities

Wetland restoration often involves invasive plant species suppression to encourage the recovery of native-dominated vegetation communities. However, assessment of recovery is usually focused only on vegetation and the response of other critical wetland biota, such as macroinvertebrates, is seldom assessed. We characterized the aquatic, semi-aquatic, and terrestrial macroinvertebrate communities in remnant, uninvaded marsh to identify restoration targets and compared this to the communities in Phragmites australis-invaded marsh, and in formerly invaded marsh that was treated with the herbicide glyphosate in 2016 to simultaneously evaluate the effects of invasion and of invasive species suppression. We sampled invertebrates in 2017 and 2018 to track two years following herbicide treatment. The invertebrate community composition captured by the emergence traps was similar between P. australis and remnant marsh, suggesting invasion has little effect on macroinvertebrate community structure. There was also high concordance between the aquatic and emerging invertebrate communities in the invaded and uninvaded habitats. In contrast, herbicide-treated sites had a unique community composition, characterized by very high densities of Chironomidae (Diptera) and low taxa richness and evenness. Herbicide-treated sites also exhibited low concordance between the aquatic and emerging invertebrate communities, potentially attributable to the sparse emerging vegetation cover providing limited substrates for emergence. Herbicide-based invasive species control results in considerable changes to the macroinvertebrate community in freshwater marshes for at least two years after treatment, which may have consequences for aquatic food webs and species that rely on macroinvertebrates as prey.

ecology↗

bioRxiv2021

Invasive grass causes biotic homogenization in wetland birds

Plant invasions often lead to homogenization of the plant community, but the potential for plant invasions to cause homogenization of other trophic levels is under-studied in many systems. We tested whether the bird community in Phragmites australis-invaded marsh would exhibit spatial and temporal taxonomic homogenization compared to remnant cattail and meadow marsh. We compared the bird community using marsh invaded by P. australis and remnant, uninvaded marsh vegetation in a year with average water depths and a year with above-average water depths in the coastal marshes of a World Biosphere Reserve. Our results demonstrate strong evidence for spatial and temporal homogenization of the wetland bird community following P. australis invasion. The birds present in P. australis-invaded marsh were a nested subset of those present in remnant marsh, and total beta diversity decreased when water depths were above average. In contrast, total beta diversity was high in remnant marsh vegetation and stable between the two years. The distinctively structured vegetation zones in remnant (uninvaded) marsh yields structural complexity and habitat heterogeneity that supports greater taxonomic turnover in the bird community. Our study provides evidence that invasion by a plant has resulted in biological homogenization of the wetland bird community.

ecology↗

bioRxiv2020

Wetland birds in the northern prairie pothole region may show sensitivity to agriculture.

Wetland losses in the Northern Prairie Pothole Region (NPPR) are largely attributed to agriculture. Since land-use is known to influence bird habitat selection, bird community composition is likely sensitive to the extent of neighboring agricultural activity. We determined which local and landscape habitat variables are most predictive of wetland bird assemblage occurrence in southern Alberta. We:1) identified distinct bird assemblages with a cluster analysis, 2) identified which species were indicative of these assemblages using an indicator species analysis and 3) predicted which bird assemblage would occur in a wetland with a classification and regression tree. Avian assemblages were more loosely defined and had few indicator species. Importantly, assemblages were specific to the natural region in which the wetland occurred. Also, landscapes with higher agricultural activity generally supported waterfowl and shorebirds, likely because agricultural activities excluded wetland-dependent birds that nest in upland habitat. Though waterfowl and shorebirds show poor sensitivity to surrounding landscape composition, edge-nesting wetland avifauna may make good indicators of ecological integrity.

ecology↗

bioRxiv2020

Bioconcentration of glyphosate in wetland biofilms

Wetland biofilms were exposed to the herbicide glyphosate via in situ field exposures and controlled microcosm experiments to measure bioconcentration and metabolism of glyphosate by biofilm organisms. Glyphosate concentrations in biofilms were orders of magnitude higher than the surrounding water, bioconcentration factors averaged 835 and 199 in field- and lab-exposed biofilms, respectively. Glyphosate in water where it had been detected in biofilms at field-exposed sites ranged from below detection (<0.001 ppm) up to 0.13 ppm. Glyphosate bioconcentration in biofilms was inversely proportional to levels in the surrounding water, and the retention kinetics were similar to both adsorption and enzymatic models. Microorganisms present in both the water and biofilms metabolized glyphosate to its primary breakdown product aminomethyl phosphonic acid (AMPA), with increased rates of breakdown in and around the biofilms. Photosynthetic efficiency of the algae within the biofilms was not affected by 24 h glyphosate controlled exposures. Our results demonstrate the role of biofilms in improving wetland water quality by removing contaminants like glyphosate, but also as a potential exposure route to higher trophic levels via consumption. Due to bioconcentration of pesticides, exposure risk to organisms consuming or living in biofilms may be much higher than indicated by concentrations in ambient water samples.

ecology↗

bioRxiv2020

Functional dispersion of wetland birds, invertebrates and plants more strongly influenced by hydroperiod than each other

The relative role of biological and abiotic filters on the assembly of co-occurring taxa is widely debated. While some authors point to biological interactions (e.g., competition) as the stronger driver of ecological selection, others assert that abiotic conditions are more important because they filter species at the regional level. Because communities influenced by a dominant abiotic filter, (e.g., Prairie Pothole Region (PPR) wetlands, each varying in ponded water permanence), often have strong cross-taxon relationships, we can study these communities to better understand the relative influence of abiotic vs biotic filters on community structure. Using functional dispersion as our measure of communities, we test six alternate hypotheses about the relative importance of various pathways representing influence of biological and permanence filters on birds, aquatic macroinvertebrates and wetland plants in the northwest PPR using structural equation modeling. We aimed to understand whether: 1) ponded water permanence alone explained functional dispersion; 2) the influence of permanence on functional dispersion was direct or mediated; and 3) abiotic filtering by permanence was stronger than biotic filtering by co-occurring taxa. The best model suggests that there is a direct influence of permanence on the functional dispersion of each taxonomic group and that both bird and macroinvertebrate functional dispersion are causally related to plant functional dispersion, though for invertebrates the influence of plants is much less than that of permanence. Thus, the relative importance of wetland permanence and the functional dispersion of co-occurring taxa depends on which taxon is considered in PPR wetlands.

ecology↗

bioRxiv2020

Suppression of established invasive Phragmites australis leads to secondary invasion

Invasive Phragmites australis (European Common Reed) is rapidly spreading throughout North American wetlands, with negative impacts on wildlife and native plants. The removal or suppression of P. australis is desired to provide an opportunity for native vegetation and wetland fauna to recover. In Ontario, managers applied a glyphosate-based herbicide to >400 ha of P. australis in ecologically significant Great Lakes coastal marshes, representing the first time this tool was used over standing water to suppress P. australis in Canada. Using a replicated Before-After-Control-Impact monitoring design, we 1) evaluated the efficacy of glyphosate-based herbicide at suppression P. australis along a water depth gradient and 2) assessed the recovery of the vegetation community for two years after treatment in relation to local reference conditions. We found that herbicide reduced live P. australis stem densities by over 99% the first year after treatment and about 95% the second year post-treatment. Treatment was equally effective along the entire water depth gradient (10 - 48 cm). The initial suppression focused management was successful, but sustained monitoring and containment focused follow-up treatment will be required to prevent reinvasion. Two years after treatment, the vegetation community does not resemble reference conditions. Although some treated plots initially increased in similarity to the vegetation communities typical of reference areas, many plots where P. australis was suppressed are on a novel trajectory comprising a vegetation community dominated by non-native Hydrocharis morsus-ranae. Secondary invasions represent a major challenge to effective recovery of native vegetation after P. australis control.

ecology↗