Vogt R.J.,University of Regina |
Matthews B.,University of Regina |
Matthews B.,Eawag - Swiss Federal Institute of Aquatic Science and Technology |
Cobb T.P.,University of Regina |
And 4 more authors.
Limnology and Oceanography | Year: 2013
In an intensive study of the vertical and horizontal distribution of zooplankton in a eutrophic lake (Katepwa Lake), we found that only adult Leptodora kindtii (> 5 mm in body size) exhibited diel vertical migration (DVM), whereas juvenile Leptodora (< 5 mm) and other zooplankton species did not. Even though a longitudinal survey of five lakes (1994-2004) indicated that variation in Leptodora density was correlated with several indicators of habitat use (e.g., water temperature) and resource availability (e.g., zooplankton abundance), feeding experiments performed in both lit and unlit conditions demonstrated that a vertebrate predator (perch) strongly reduced Leptodora abundances under all conditions and always preferentially selected large-bodied individuals. Collectively, this evidence suggests that the migratory behavior of large Leptodora is consistent with an anti-predator defense strategy. To estimate the ecological significance of Leptodora DVM behavior, we modeled how predation rates on different zooplankton taxa differed between day and night in Katepwa Lake. We found that Leptodora had as much as five-fold higher prey-specific predation rates at night, particularly for intermediate-sized prey. We conclude that ignoring the habitat use, size-structure, and vertical migration behavior of Leptodora could considerably underestimate the significance of invertebrate predation in lake food webs, particularly in eutrophic lakes where Leptodora can coexist at high densities with planktivorous fish. © 2013, by the Association for the Sciences of Limnology and Oceanography, Inc.
Caners R.T.,Alberta Biodiversity Monitoring Institute |
Lieffers V.J.,University of Alberta
Restoration Ecology | Year: 2014
Peatlands in northern Alberta, Canada, are being rapidly impacted by oil sands activities, with potentially long-term consequences for their recovery. In situ oil sands extraction requires exploration of oil resources on a dense network of drilling pads across the landscape. This study examined the recovery of wooded moderate-rich (WMR) fens 10years after abandonment of these sites with minimal restorative measures. Bryophyte and vascular plant diversity, site microtopography, and water chemistry were assessed on drilling pads and in adjacent areas of undisturbed reference habitat. WMR fens affected by drilling activities were divided a priori into two groups based on strongly divergent trends in their successional development. One group represented the majority of WMR fens observed on the land base; at these sites hummock-forming mosses including minerotrophic Sphagnum species were infrequent and tree recruitment was almost absent. The other group was dominated by Sphagnum species, had Picea mariana and Larix laricina recruitment, and appeared to recover more quickly. Both groups had high abundance of wetland sedges, notably Carex aquatilis. Further, drilling pads belonging to the first group had a high water table, limited elevated microsites, and had surface flooding over a portion of the growing season, in contrast to Sphagnum-dominated sites. Development of the aquatic, bryophyte-poor wetland type is comparable to early stages of wetland succession and these systems will recover relatively slowly, likely from decades to more than a century. Restoring part of the vertical distribution of microhabitats before abandonment of these pads could stimulate the successional recovery of vegetation. © 2014 Society for Ecological Restoration.
But we don't know a lot about bees in Alberta—there isn't even a complete record of what species live in the province. Jessamyn Manson, an assistant professor in the Department of Biological Sciences, is helping change that; essentially, her goal is to figure out how many bees and which species are in the province, and where. "We don't know what bees were doing years ago so we don't know if things have changed," says Manson. "There's a very good chance we're losing species, and we don't know. This work is the foundation of our tracking." Manson also wants to know which wild bees are pollinating which plants. The data she gathers will help lay the foundation for what we know about bees across Alberta. It builds on the university's current collections of bees found in the province. She is also collaborating with the researchers working on the Alberta Biodiversity Monitoring Institute's Ecosystem Services Assessment project, which aims to assess pollination services provided by native bees and provide new information on the diversity of species and their ranges across Alberta. Manson echoes what you hear from other biologists: research is vital to understanding and addressing issues of human-induced climate change. Without long-term, comprehensive data, you can't see the patterns of a species' behaviour or determine whether climate change is affecting that species. Her work is a first step in a long process, but Alberta is a great place to do it, given its abundance of agricultural and natural regions, says Manson. In general, most studies examining changes in bee communities have focused on the effects of pesticides and land use; researchers have only recently started to consider the role of climate change in current and future bee distributions. Manson refers to a paper published in summer 2015, led by Jeremy Kerr from the University of Ottawa. "It was one of the first really big papers looking at wild bees and climate change," Manson says. The study used observations across North America and Europe over 110 years. Manson expected it would show a decrease in the southern range of bees coupled with an increase in the northern range—basically assuming that bees were moving into the cooler north as the south heated up. Instead, the study indicates that, while the more southerly bees are moving north, northerly bees are not shifting their range northward; the bottom end of their range is shrinking while the top end of their range is staying the same. The bees are being squeezed into a smaller area. "It was a surprise," says Manson. Researchers aren't certain what is causing the bees to leave the southern part of their range, but it's worth noting that the study ruled out land use and pesticides as causes for the shift. Temperature, however, is correlated. The research is young, but Manson says the data show that climate change is probably affecting bees. As for what that means in Alberta, the research is only beginning. "They're doing their job in the background," Manson says of her study subjects. "We don't really notice bees until they're not there." Jessamyn Manson and her students have spent the past two summers systematically collecting bees in Alberta, from the Montana border to Grande Prairie. The days are hot and long—sometimes they are in the truck for 12 hours or more. Wearing bug shirts with hoods and mesh panels so they can avoid using insect repellent, the small army of bee biologists strategically sets up pan traps along a planned grid. On days where there is only a light breeze, the students might also use nets to capture the bees. But it's when they return to the lab that the truly painstaking work begins. The students have collected an estimated 18,800 bees from more than 200 sites and identified more than 85 species of wild bees living in Alberta. The team also measures air temperatures and precipitation to learn how bees relate to habitat and climate variables. You can help by planting a bee-friendly garden with flowers that bloom at different times. Bee species have different tongue lengths, so a variety of shapes and sizes will attract a diversity of bees. Native or heirloom plants are excellent choices. Crocuses are popping out of the snow two weeks earlier than they did in the 1940s. So what happens if pollinators can't follow suit? Who doesn't love an early spring? Certainly the prairie crocus and the aspen crocus have been taking advantage of warmer weather by flowering earlier. A study by two researchers from the U of A's Department of Renewable Resources shows that over 71 years, from 1936 to 2006, these Alberta plant species bloomed two weeks earlier at the end of the study than they had at the beginning. Aspen and prairie crocus awoke earlier in the season due to less snow cover and substantial warming—a mean monthly temperature increase of 5.3C in February and 1.5C in May, found Elisabeth Beaubien, '91 MSc, '13 PhD, research associate and longtime co-ordinator of Alberta PlantWatch (a citizen science effort to record plant bloom times), and Andreas Hamann, associate chair of research in the renewable resources department. Spring plant phenology (when flowers emerge) is one of the most immediate and easily observed responses to climate change in temperate regions, according to the study. So what does an earlier bloom mean for bees? Bee researcher Jessamyn Manson isn't sure if the flowers and bees will meet up in the spring. "The change is happening so quickly," she says. "Two weeks doesn't sound like a lot but it's scary. The bees are not able to adapt fast enough. These are animals that are built to adapt, but they can't keep up." If the bees and flowers don't meet to perform their pollen dance, the consequences will be severe. It would mean a reduction in flower diversity from alpine meadows to backyard gardens. This would lead to decreased soil quality and lower-quality forage for animals, including cattle. Agriculture would suffer and only self-fertilizing plants would persist. There would be less biodiversity, fewer plants and animals, poorer water quality and more soil erosion. In fact, it's already happening. Beaubien cites a 2015 study by the U.S. Geological Survey that found berry harvests in Alaska may be declining or becoming increasingly unpredictable due to less snowfall and warmer winters. Studies like this have her concerned. "Things seem to be a little out of whack. We need our PlantWatch citizen scientists to note down bloom dates so we can better understand the changes that result when the climate warms up," Beaubien says. Explore further: Bees use colour-coding to collect pollen and nectar
Bayne E.,University of Alberta |
Leston L.,University of Alberta |
Lisa Mahon C.,Environment Canada |
Solymos P.,University of Alberta |
And 9 more authors.
Condor | Year: 2016
Responses of boreal birds to changes in forest structure and composition caused by construction of well pads, seismic lines, and pipelines are poorly understood. Bird species associated with older forests are predicted to experience larger population declines with increased disturbance compared with species associated with younger or open habitats; however, point count methods may influence apparent outcomes because the proportional area of disturbed vegetation and the magnitude, uncertainty, and detection of a disturbance response by birds vary as a function of sampling area. We analyzed point count data from 12 energy sector studies and measured how disturbance type and point count radius interacted to affect 531 impact ratios (mean abundance at point counts centered within disturbances relative to abundance at point counts within forest 150-400 m from the nearest edge bordering those disturbances [59 species∗3 disturbance types∗3 point count radii]). We observed larger disturbance effects (impact ratios) within larger-radius point counts at well pads (100-m and unlimited-distance) and pipelines (unlimited-distance) compared with 50-m point counts at seismic lines, and within 50-m point counts at well pads relative to 50-m point counts at seismic lines. Effect uncertainty was higher at well pads and pipelines than seismic lines, and lower within larger-radius point counts. The probability of detecting a disturbance response was greater for larger-radius point counts at pipelines than for 50-m point counts at seismic lines, and within 50-m point counts at well pads relative to 50-m point counts at seismic lines. On average, a species was more likely to increase in abundance near an energy sector disturbance if the species was not associated with older (.75 yr) forest stages. While the effects of disturbance varied by species and with disturbance type, the effects of pipelines and seismic lines were better detected by largerradius point counts, while the effects of well pads were better detected by smaller-radius point counts. © 2016 Cooper Ornithological Society.
Mollard F.P.O.,University of Alberta |
Mollard F.P.O.,University of Buenos Aires |
Roy M.-C.,University of Alberta |
Roy M.-C.,Alberta Biodiversity Monitoring Institute |
Foote A.L.,University of Alberta
Environmental Monitoring and Assessment | Year: 2015
Companies mining oil sands in Alberta (Canada) face the challenge of reclaiming wetlands under water use restrictions. Wetland reclamation after mining will generate marshes characterized by elevated salinity and residual hydrocarbons. Oil sands wetlands are also impoverished in forbs, suggesting that their establishment may be constrained by water chemistry. We transplanted skullcap, mint, and smartweed plants into experimental trenches that simulated two possible reclamation scenarios: wetlands amended with on-site freshwater or with oil sands processed water (OSPW). The main scientific question was is OSPW a suitable water amendment as freshwater for reclaiming wetland forb habitat? As a surrogate of plant health, we studied plant ecophysiology (gas exchange, leaf fluorescence), leaf chemistry, and plant growth. Results showed that there were no differences in skullcap mineral contents under either treatment; however, mint and smartweed plants subjected to OSPW had a significantly higher Na content than those under freshwater. Smartweed dark-adapted leaf fluorescence showed a reduced photochemistry in OSPW relative to plants in freshwater. Mint leaves exhibited lower stomatal conductance in OSPW than in freshwater, a condition that negatively affected transpiration and carboxylation. Skullcap plants grown in OSPW had lower net CO2 assimilation rates than those in freshwater but did not show any other ecophysiological difference between treatments. Mint plants experienced growth reductions (i.e., shoot height) in OSPW. Our results show, for the first time in the literature, that plants photosynthetic capacity was negatively affected by OSPW. Conditions in OSPW proved to be suitable for establishment as transplanted forbs showed 100 % survival after the first growing season. However, impaired physiological functions in plants subjected to OSPW indicated that OSPW amendment created a less hospitable habitat for wetland forbs than freshwater. © 2015, Springer International Publishing Switzerland.