Department of Ecology &amp; Evolutionary Biology

Connaught Fund

Environment

Graduate Students

Indigenous

Faculty of Arts & Science Staff

Sustainability

PhD student Jaime Grimm’s research into fish pathogens and salmon conservation – and how she conducts that research – is the culmination of growing up amidst the rich ecosystems of Canada’s West Coast, parents who nurtured a love of nature in her, and her Salteaux First Nations heritage.

“Growing up in British Columbia, I spent a lot of time in nature,” she says, “which was a hugely privileged position to be in. We went camping every summer and my mother and I would spend all day looking for frogs and toads and salamanders – it was like a treasure hunt. She inspired that interest in me.”

In high school, Grimm started taking biology courses. “I was like wow, this is so interesting, so fun. We did a section on marine invertebrates – sea slugs, clams, crabs. I was completely enamored and decided then that I wanted to pursue a science degree and be a biologist.”

Today, Grimm is a PhD student in the Faculty of Arts & Science's department of ecology and evolutionary biology (EEB), supervised by Associate Professor Martin Krkosek and Adjunct Professor Andrew Bateman of the Pacific Salmon Foundation.

A salmon farm on the coast of British Columbia. Some may contain as many as a million fish (photo courtesy of Clayoquot Action)

She was recently named a Connaught PhDs for Public Impact Fellow by the School of Graduate Studies. The fellowship will enable her to engage the public in her work through training in science communication and public policy, and project-specific funding.

Grimm's research with Krkosek and Bateman is centred around the enormous salmon farms located in the coastal waters of B.C. The farms are giant pens made of nets so that ocean water circulates through them. Because of the high population density – some hold as many as a million fish – the pens are ripe breeding grounds for pathogens such as bacteria, viruses and fungi which can then threaten wild salmon populations.

Juvenile salmon returning to the ocean from spawning grounds in coastal creeks and rivers are particularly vulnerable. Their immune systems haven’t fully developed. Also, young fish aren’t normally exposed to diseases carried by mature fish because the latter are typically far out at sea when the former return to the ocean.

“But now we're adding these farms right on the migration routes of juvenile salmon,” says Grimm. “So, you have this big, potential source of disease that young salmon are encountering at this vulnerable stage in their lives. It's an enormous issue.”

What’s more, farms can be close together; Grimm is trying to determine if a pathogen outbreak in one can ride coastal currents to another.

Juvenile salmon native to the West Coast are at risk from pathogens that spread from salmon farms (photo courtesy of Jaime Grimm)

Like Krkosek, Grimm is committed to finding socially and ecologically just wildlife conservation solutions that recognize Indigenous rights and sovereignty. Her work, she points out, takes place in partnership with and on the unceded lands of coastal First Nations, including the Ahousaht First Nation, the Tla-o-qui-aht First Nation and the Mowachaht/Muchalaht First Nation.

She also recognizes that salmon conservation is intimately tied to Indigenous rights because of the importance First Nations place on salmon. “Of course, they’re a source of livelihood and sustenance,” says Grimm, “but they're also essential components of culture. These salmon have spawned and lived in these rivers since time immemorial and, during that time, have been stewarded well by the people who live there.

“And now that this system is being disrupted, it's critically important that we recognize and value Indigenous knowledge and get back to the roots of what was working so well. This is their land, their unceded territory – they should have final say over what's happening.”

According to Krkosek, “Pacific salmon are a keystone species to coastal ecosystems and a centrepiece of the identity and food security of First Nations in coastal B.C. Jaime’s work on salmon aquaculture and infectious diseases is providing essential information to First Nation’s decision-making regarding salmon management in their territories.”

Grimm’s partnership with First Nations includes developing relationships with fisheries managers who work for First Nations, understanding their needs, developing research questions together – and being out on the water together conducting field work.

“The biggest part of it is building a relationship and building trust,” says Grimm. “And making sure we don’t just go in and extract data or knowledge and then leave. It's about working towards a shared goal.”

The Connaught fellowship will help Grimm build on those relationships. One of the projects she is considering is developing workshops for training community members to collect water samples and extract DNA from them in order to learn about the pathogens that are present. Not only would this help Grimm in her work, it would also make it possible for communities to do their own testing in support of their own autonomy and advocacy.

Another potential project lies at the intersection of her scientific endeavors and commitment to science communication. “I’d like to hire an artist from one of the First Nations I'm currently working with to produce a graphical representation of this research,” she says.

“My aim is to publish my scientific results in a peer-reviewed journal but in that form, it will only be accessible to a small group of people. So, I would like to have this beautiful, artistic piece that would be much more accessible that I could share with many more people.”

Grimm is spending the winter in Krkosek’s lab in Toronto but she’s looking forward to being back on the west coast next spring and, at the same time, is looking far into the future.

“I think this will be the journey for the rest of my life,” she says. “Learning how to do this right and do it well. The path I'm on now is difficult and humbling, but it’s what I hope the rest of my career will look like.”

Intensive agriculture turned a wild plant into a pervasive weed, study finds

lanthierj — Tue, 13 Dec 2022 22:52:36 +0000

Intensive agriculture turned a wild plant into a pervasive weed, study finds

lanthierj Tue, 12/13/2022 - 17:52

Cutline

Lead author Julia Kreiner performing DNA extractions of historical herbarium samples in the ancient DNA lab in Tuebingen, Germany (all photos courtesy Julia Kreiner/University of British Columbia)

Topic

Agriculture

Collaboration

New research published in Science shows how the rise of modern agriculture turned a North American native plant, common waterhemp, into a problematic agricultural weed.

An international team led by researchers at the University of British Columbia with colleagues at the University of Toronto, compared 187 waterhemp samples from modern farms and neighbouring wetlands with more than 100 historical samples dating as far back as 1820 that had been stored in museums across North America.

Much like the sequencing of ancient human and neanderthal remains has resolved key mysteries about human history, studying the plant’s genetic makeup over the last two centuries allowed the researchers to watch evolution in action across changing environments.

“The genetic variants that help the plant do well in modern agricultural settings have risen to high frequencies remarkably quickly since agricultural intensification in the 1960s,” said study lead author Julia Kreiner. A postdoctoral researcher in UBC’s department of botany, Kreiner completed her PhD at U of T with study co-authors John Stinchcombe and Stephen Wright, both professors in the department of ecology and evolutionary biology in the Faculty of Arts & Science at U of T.

Waterhemp occurring in natural habitats, the sandy merging of a lake in southern Illinois.

The researchers discovered hundreds of genes across the weed’s genome that aid its success on farms, with mutations in genes related to drought tolerance, rapid growth and resistance to herbicides appearing frequently.

“The types of changes we’re imposing in agricultural environments are so strong that they have consequences in neighbouring habitats that we’d usually think were natural,” said Kreiner.

The findings could inform conservation efforts to preserve natural areas in landscapes dominated by agriculture. Reducing gene flow out of agricultural sites and choosing more isolated natural populations for protection could help limit the evolutionary influence of farms.

A 155-year-old waterhemp herbarium specimen from the Missouri Botanical Garden Herbarium

Common waterhemp is native to North America and was not always a problematic plant. Yet in recent years, the weed has become nearly impossible to eradicate from farms thanks to genetic adaptations including herbicide resistance.

Notably, five out of seven herbicide-resistant mutations found in current samples were absent from the historical samples. “Modern farms impose a strong filter determining which plant species and mutations can persist through time,” said Kreiner. “Sequencing the plant’s genes, herbicides stood out as one of the strongest agricultural filters determining which plants survive and which die.”

Waterhemp carrying any of the seven herbicide resistant mutations have produced an average of 1.2 times as many surviving offspring per year since 1960 compared to plants that don’t have the mutations.

Herbicide resistant mutations were also discovered in natural habitats, albeit at a lower frequency, which raises questions about the costs of these adaptations for plant life in non-agricultural settings.

“In the absence of herbicide applications, being resistant can actually be costly to a plant, so the changes happening on the farms are impacting the fitness of the plant in the wild,” said Kreiner.

“While waterhemp typically grows near lakes and streams, the genetic shifts that we’re seeing allow the plant to survive on drier land and to grow quickly to outcompete crops,” said co-author Sarah Otto, Killam University Professor at UBC. “Waterhemp has basically evolved to become more of a weed given how strongly it’s been selected to thrive alongside human agricultural activities.”

Agricultural practices have also reshaped where the weedy variety of common waterhemp can be found to grow on the North American continent. Over the last 60 years, a weedy southwestern variety has made an increasing progression eastward, spreading their genes into local populations as a result of their competitive edge in agricultural contexts.

Waterhemp can drastically reduce corn and soy yields, as seen on the right in a corn field in Essex County, Ontario

“Understanding the fate of these variants and how they affect plants in non-farm, ‘wild’ populations is an important next step for our work,” says Stinchcombe.

The researchers also plan to delve further into their discoveries on the rate of plant evolution over different geographic and temporal scales, with the hope of uncovering how variation in land-use across changing landscape influences the evolution of native plants.

“These results highlight the enormous potential of studying historical genomes to understand plant adaptation on short timescales,” says Wright. “Expanding this research across scales and species will broaden our understanding of how farming and climate change are driving rapid plant evolution.”

Broadly speaking, the researchers say the findings mean greater consideration of the impact of farming practices on native plants is needed.

“On one hand, preserving natural areas within agricultural landscapes provides an important ecological service,” says Kreiner. “On the other hand, these natural populations will become quite genetically different from what they would have looked like in the absence of agriculture. How well these plants will be able to persist in their native habitats remains a mystery.”

With files from the University of British Columbia

Nature's scuba tanks? Researchers discover how Anolis lizard breathes underwater

lanthierj — Fri, 14 May 2021 16:25:01 +0000

Nature's scuba tanks? Researchers discover how Anolis lizard breathes underwater

lanthierj Fri, 05/14/2021 - 12:25

Cutline

Close-up of an Anolis lizard with a rebreathing bubble on its snout (photo by Lindsey Swierk)

Chris Sasaki

Topic

Global

A team of evolutionary biologists from the University of Toronto has shown that Anolis lizards, or anoles, are able to breathe underwater with the aid of a bubble clinging to their snouts.

Anoles are a diverse group of lizards found throughout the tropical Americas. Some anoles are stream specialists. The semi-aquatic species frequently dive underwater to avoid predators, where they can remain submerged for as long as 18 minutes.

“We found that semi-aquatic anoles exhale air into a bubble that clings to their skin,” says Chris Boccia, an alumnus of the Faculty of Arts & Science’s department of ecology and evolutionary biology.

Chris Boccia is a recent master of science graduate from the Faculty of Arts & Science’s department of ecology and evolutionary biology (photo courtesy of Chris Boccia)

“The lizards then re-inhale the air, a maneuver we’ve termed ‘rebreathing’ after the scuba-diving technology.”

Boccia is lead author of a paper describing the finding published in the journal Current Biology.

The researchers measured the oxygen content of the air in the bubbles and found that it decreased over time, confirming that rebreathed air is involved in respiration. Rebreathing likely evolved because the ability to stay submerged longer increases the lizard’s chances of eluding predators, the authors say.

The authors studied six species of semi-aquatic anoles and found that all possessed the rebreathing trait, despite most species being distantly related. While rebreathing has been studied extensively in aquatic arthropods like water beetles, it was not expected in lizards because of physiological differences between arthropods and vertebrates.

“Rebreathing had never been considered as a potential natural mechanism for underwater respiration in vertebrates,” says Luke Mahler, an assistant professor in the department of ecology and evolutionary biology and Boccia’s thesis supervisor.

“But our work shows that this is possible and that anoles have deployed this strategy repeatedly in species that use aquatic habitats.”

Luke Mahler is an assistant professor in the department of ecology and evolutionary biology (photo courtesy of Luke Mahler)

Mahler and co-author Richard Glor, from the University of Kansas, first observed anoles rebreathing in Haiti in 2009, but were unable to carry out further observations or experiments. Another co-author, Lindsey Swierk, from Binghamton University, State University of New York, described the same behaviour in a Costa Rican species in 2019. These early observations suggested that rebreathing was an adaptation for diving, but this idea had not been tested until now.

Boccia says he became interested in aquatic anoles after encountering one in Panama. He began his rebreathing investigations in Costa Rica in 2017 and continued the research in Colombia and Mexico.

As the authors note, the rebreathing trait may have developed because anoles’ skin is hydrophobic – it repels water – a characteristic that likely evolved in anoles because it protects them from rain and parasites. Underwater, air bubbles cling to hydrophobic skin and the ability to exploit these bubbles for breathing developed as a result.

While further work is required to understand how the process works in detail, Boccia, Mahler and their co-authors suggest different ways in which rebreathing may function.

In its simplest form, the air bubble on a lizard’s snout likely acts like a scuba tank, providing a submerged animal with a supply of air in addition to the air in its lungs. This is what aquatic arthropods like water beetles do to extend the time they can remain submerged.

The researchers also suggest that the rebreathing process may facilitate using air found in a lizard’s nasal passages, mouth and windpipe that would otherwise not be used by the lizard in breathing.

The bubble may also help rid waste carbon dioxide (CO2) from exhaled air through a process other researchers have already observed in aquatic arthropods. Those studies concluded that, because CO2 is highly soluble in water, and because the level of CO2 in the bubbles is higher than in the surrounding water, exhaled CO2 dissolves into the surrounding water rather than being rebreathed.

Finally, the authors speculate that the bubble may act as a gill and absorb oxygen from the water – again, something already observed in arthropods. Boccia and Mahler are planning further research to confirm if these rebreathing processes are occurring with anoles.

“This work enriches our understanding of the creative and unexpected ways that organisms meet the challenges posed by their environments,” says Mahler. “That is valuable in its own right, but discoveries like this can also be valuable to humans as we seek solutions to our own challenging problems.”

“It’s too early to tell if lizard rebreathing will lead to any particular human innovations,” says Boccia. “But biomimicry of rebreathing may be an interesting proposition for several fields – including scuba-diving rebreathing technology, which motivated our naming of this phenomenon.”

The research was supported by the Natural Sciences and Engineering Research Council of Canada, among others.

U of T researchers explore how to prevent the flow of harmful microplastics from washing machines into waterways

Romi Levine — Fri, 08 Feb 2019 19:13:11 +0000

U of T researchers explore how to prevent the flow of harmful microplastics from washing machines into waterways

Romi Levine Fri, 02/08/2019 - 14:13

Cutline

Washing machines can release microfibres into waterways, but there are ways of mitigating it, a U of T study finds (photo via Getty Images)

Romi Levine

Topic

Our Community

Graduate Students

Undergraduate Students

University of Toronto researchers are tracking the source of tiny pieces of plastic, called microplastics, that are making their way into Canadian waterways – one laundry load at a time.

A study led by undergraduate students Hayley McIlwraith and Jack Lin, and Chelsea Rochman, an assistant professor of ecology and evolutionary biology, looks at how washing machines play a part in the release of synthetic microfibres (a kind of microplastic) into the environment, and the most effective ways of mitigating the problem. They specifically looked at two different products marketed as being able to reduce the amount of microfibres released by washing machines: Cora Ball and Lint LUV-R filter.

U of T News spoke with Rochman about the team’s findings.

What went into studying microfibres in washing machines?

We know washing machines are a source of microfibres out into the lake or into the environment. We were interested to know how many microfibres shed from a single fleece blanket when we do a load of laundry. What we really wanted to know is if we implement these mitigation strategies that are currently on the market, how much would it mitigate the amount of microfibres that leave our washing machines and head to the waste water treatment plant?

There are two undergrads that led the project, Hayley McIlwraith and Jack Lin. First they developed a method to be able to quantify the microfibres in an efficient way because it's not easy. And then they did laundry and quantified the microfibres in the washing machine effluent with and without those mitigation technologies – and then we compared.

We found that if you put an after-market filter on your washing machine, which anyone can do – you can buy them online – it mitigates almost 90 per cent of all the fibers going out the back of the wash.

What kind of fabrics release microfibres?

They can come from cotton materials, too, but the majority of our clothing these days is polyester and other types of plastics. A lot of textiles in the clothing we wear is made out of plastic, so when they shed fibers, they are microplastic.

What would you want people to know about what their clothes are releasing into the environment?

A lot of people hear about plastic pollution and microplastic in our lakes, but I don't think people realize that the majority of what we find, especially in freshwater environments, are these microfibres – these tiny little bits of textiles. While they probably also come from fishing gear and some of it comes from dust, we know that washing our clothes are a source. Every time we wash our clothes –whether it's the fibers, the chemicals associated with them, and of course dirt and other things that come out into the wash water – they exit out of our house and into the waste water treatment plant, where some of them will still make their way out to the lake.

A lot of people clean out their lint trap in their dryer. They are in the habit of it and they do it because they're told it's a safety hazard. We're not talking about anything different in washing machines – we're talking about wet lint instead of dry lint. I don't think everyone realizes we are talking about laundry lint.

In my opinion, it's not about every single person on the planet buying an after-market filter, it's more that washing machines should be made to have lint traps in them the way dryers do.

Will you be continuing to study microfibres in laundry?

We’re taking this small study and turning it into a pilot. My graduate student Lisa Erdle and my colleagues at Georgian Bay Forever are leading a study where they are putting filters in the homes of 100 different people in Parry Sound. In the township of Parry Sound, the waste water treatment plant operators are allowing us to sample before and after these people put them in their homes.

Read the full study

Hairy legs and inflatable abdomens: How female dance flies attract males

lanthierj — Tue, 25 Sep 2018 04:00:00 +0000

Hairy legs and inflatable abdomens: How female dance flies attract males

lanthierj Tue, 09/25/2018 - 00:00

Cutline

In dance flies, some females use their hairy legs and inflatable abdominal sacs to make themselves appear bigger – and more attractive – to potential partners

Elaine Smith

Topic

Global Lens

Alumni

Global

Graduate Students

U of T Mississauga

When it comes to the mating game, it’s true that size does matter for North American male dance flies, who are most attracted to mates who display the largest inflatable abdominal sacs, says Rosalind Murray, a post-doctoral researcher in biology at the University of Toronto.

Murray’s research, published last week in Proceedings of the Royal Society B, focuses on one of the rare insect species (Rhamphomyia longicauda) in which the female partner displays sexual ornamentation to attract mates to fertilize her eggs. It is much more for common for males to display ornamentation, because doing so requires energy. The female generally devotes this energy to producing eggs and parenting.

Before and after inflation for a female Rhamphomyia longicauda

Murray and researchers from U of T Mississauga and the University of Stirling in Scotland explored the attractiveness of two sexual ornaments common among North American female dance flies: inflatable abdominal sacs and leg scales. She and her colleagues demonstrated that larger, inflated abdominal sacs are the most alluring to the males of the species. Leg scales are important to mates only if the female in question has a small abdomen – and among this population, the males prefer females with larger leg scales.

The experimental research to discover male mating responses to female ornamentation took place during field tests on an island in the Credit River, near Glen Williams, Ont., over a 10-day period. Murray created models of female fly silhouettes from plastic transparencies, varying the abdominal size and leg size separately. Five models at a time were hung on fishing line and positioned at the mating swarm site. Swarms occurred daily at dawn and dusk and involved large numbers of both males and females. As a swarm began, Murray and her colleagues observed and recorded each approach a male fly made to one of the silhouettes.

Murray says there are two theories about why large sexual ornaments have developed among the female dance flies. The large abdomens and leg scales may honestly signal that the females have the most or largest eggs and are the best bet for the male to father the most offspring. Alternatively, they may serve as a symbol of sexual conflict between the sexes: All of the females want to attract males, but large abdominal sacs and/or large leg scales may be deceiving males about the number and size of eggs available for fertilization within a female.

Why do female dance flies go to such extreme lengths to attract males? Each time he mates, the male provides the female with gifts of food that allows her to nourish her eggs. As a result, the females might mate more frequently during the mating period than the males.

These findings are of particular interest because they shed light on what controls sexual differences in the animal kingdom, says co-author Darryl Gwynne, a professor of biology at U of T Mississauga.

“The males are generally the showy sex and the females are usually the ones who are choosy about mates, so this species is one of a handful where the roles are reversed in mating behaviour,” he says. “This research will help us to understand why the sexes are so different.”

The study was partly supported by the Natural Sciences and Engineering Research Council of Canada.

Plastic not just a problem in our oceans, also affecting the Great Lakes: U of T research

ullahnor — Mon, 18 Jun 2018 15:24:44 +0000

Plastic not just a problem in our oceans, also affecting the Great Lakes: U of T research

ullahnor Mon, 06/18/2018 - 11:24

Cutline

Plastic water bottle in the Pacific Ocean. An international conference being held at U of T Scarborough will explore issues including plastic polluting the Great Lakes (photo by Citizen of the Planet/Education Images/UIG via Getty Images)

Don Campbell

Topic

Global Lens

Climate Change

Environmental Science

International

U of T Scarborough

When it comes to plastics polluting our water, it’s not just the world’s oceans that should keep us concerned.

Chelsea Rochman, assistant professor of ecology and evolutionary biology at the University of Toronto, says we should be paying close attention to what's taking place closer to home in the Great Lakes.

“The contamination in the Great Lakes and other bodies of freshwater from plastics and microplastics is ubiquitous,” says Rochman, who looks at plastic debris and its associated chemical contaminants.

Pollution from plastics is just one of many environmental issues to be explored during the annual conference of the International Association for Great Lakes Research (IAGLR), taking place June 18 to 22 at U of T Scarborough. It’s the largest scientific event held in the Great Lakes area with more than 800 participants from countries all over the world, and will feature more than 50 scientific presentations.

Rochman points to published research, in addition to work in her lab and with colleagues, that finds the concentration of plastics in parts of the Great Lakes are equal to or greater than those reported in the ocean. Their work in Lake Ontario, Lake Superior and Lake Huron has also found microplastics (particles five millimetres and smaller) in nearly all fish collected.

This shouldn’t come as a surprise, says Rochman. Canada and the United States discard about 22 million pounds of plastic into the Great Lakes annually and unlike oceans, which get flushed out by global currents, the lakes are less diluted.

Most plastics end up in the Great Lakes from stormwater runoff through rivers or streams, from wastewater treatment plants or litter blown directly into the lakes. Other sources include agricultural runoff and maritime debris like fishing gear. Rochman’s own research on microplastics has uncovered pollution from tiny bits of tire dust, microfibers from clothing, glitter, plastic bottles and microbeads found in face wash.

“Toxicity tests show that microplastics can be harmful to wildlife, impacting growth, feeding behaviour, survival and reproduction,” she says.

Assistant Professor Chelsea Rochman (right), an expert on water pollution from plastic contaminants, says the concentration of plastics in parts of the Great Lakes rivals those in the oceans

Rochman says a lot of the research on plastic pollution in the Great Lakes is still in its infancy, but it’s becoming a hot topic of environmental research. One line of her lab’s current research is focusing on how plastics move through Great Lakes food webs, and how this contamination may affect local aquatic wildlife.

“It’s exciting to be part of a group of researchers that are really moving the needle on microplastics in freshwater,” she says. “I think the research we will see in the next few years will be eye-opening.”

The Great Lakes basin is home to 43 million inhabitants in Canada and the U.S. It accounts for 58 per cent of Canada’s economy, while $311 billion of Ontario’s annual exports derive directly from its natural resources, including municipal and industrial water supplies, fish harvesting and land uses.

“There’s no question it’s an invaluable economic resource, but it’s also home to numerous natural aquatic habitats that, in many ways, remain under threat,” says Professor George Arhonditsis, chair of the department of physical & environmental sciences at U of T Scarborough and co-chair of the conference.

In addition to pollution from plastics, there’s also the threat from parasites, invasive species, algae blooms, habitat loss and various other forms of pollution. The conference will be looking at developing effective environmental policy to protect them.

“We will have leading experts covering important environmental issues facing the Great Lakes, the important scientific research being done in the lakes as well as sessions on governance and environmental policy,” adds Arhonditsis, an expert in food web ecology and biogeochemical modelling.

Arhonditsis and fellow conference co-chair Mathew Wells, an associate professor of physical & environmental science at U of T Scarborough, both note the significant work done over the past few decades in cleaning up the Great Lakes.

“Just 20 to 30 years ago, you couldn’t safely eat the fish in the Great Lakes because toxic PCB levels were so high,” says Wells, an expert on environmental fluid dynamics.

“Much of that has changed because the water quality has improved, and much of it comes down to good science and environmental agreements made between Canada and the United States. Problems exist, but in many respects there are great news stories about the work that’s been done.”

Associate Professor Mathew Wells an expert on environmental fluid dynamics does much of his research in the Great Lakes

Dragonfly enzymes point to how they interact in ecosystem: U of T research

noreen.rasbach — Wed, 23 May 2018 16:52:26 +0000

Dragonfly enzymes point to how they interact in ecosystem: U of T research

noreen.rasbach Wed, 05/23/2018 - 12:52

Cutline

A four-spotted skimmer dragonfly (photo courtesy of Shannon McCauley)

Nicolle Wahl

Topic

Biology

U of T Mississauga

New research by University of Toronto scholars reveals that understanding small physiological activities in dragonflies could reveal a deeper understanding of how they interact with other organisms in an ecosystem.

“We often think communities [of dragonflies] are so complex,” says Shannon McCauley, an assistant professor of biology at U of T Mississauga. “It looks like the underlying physiological mechanisms could simplify our understanding of ecological dynamics.”

Dragonflies are common near lakes, streams and ponds where they catch insects like mosquitoes, moths and midges. Although they seek cover in plants and have large eyes with nearly 360-degree vision, they can become prey for birds, fish, spiders, frogs and even other dragonflies. After hatching from an egg, dragonflies live in water as aquatic nymphs, feeding on insects, tadpoles and small fish.

In a paper published in the latest issue of the Proceedings of the National Academy of Science, McCauley and her colleagues, Denon Start, a PhD candidate, and Ben Gilbert, an associate professor in the department of ecology and evolutionary biology, studied 17 species of nymph-stage dragonflies in ponds in and around the Koffler Scientific Reserve, located roughly 60 kilometres north of the downtown U of T campus. .

They determined that in ponds without large fish, they were more likely to find dragonfly nymphs with high activity rates but lower “burst speeds” – a capability to swim explosively away from a potential predator. Alternately, in ponds with large fish, dragonfly nymphs with low activity rates but high burst swimming speeds were more common.

But the team took this a step further. They were able to link high levels of an enzyme called lactate dehydrogenase (Ldh) to high activity rates and high levels of the enzyme arginine kinase (Ak) to fast burst speeds.

The team found that the activity of these two enzymes accounted for more than 80 per cent of the variation in dragonfly community composition.

“It’s a further step down the scale of biology,” says McCauley. “It suggests that we can look at these low levels of biological co-ordination and make predictions about communities."

Beyond our oceans: Microplastics pollute rivers and lakes too

ullahnor — Fri, 27 Apr 2018 15:20:47 +0000

Beyond our oceans: Microplastics pollute rivers and lakes too

ullahnor Fri, 04/27/2018 - 11:20

Cutline

Researchers are finding plastics in fish in freshwater ecosystems (Shutterstock)

Chelsea Rochman

Kennedy Bucci

Topic

Our Community

Environment

The Conversation

Subheadline

The Conversation with Kennedy Bucci and Chelsea Rochman

When you think of microplastic pollution, plastic debris less than five millimetres in size, you likely envision the ocean – probably because ocean gyres gained notoriety for being a microplastic soup.

But what about our lakes, rivers, forests and fields? They can be just as contaminated with microplastic debris as the oceans.

Until recently, these environments were described as conduits – ways for plastics to get to the oceans. But now we’re seeing rivers, lakes and soil in a different light, as reservoirs for plastic particles.

We now know that agricultural land, surface waters, freshwater lakes and river sediments are also contaminated.

In the past five years, researchers have started to study the sources, fates and effects of microplastics in freshwater and terrestrial ecosystems, but only a handful of studies have been done so far.

Microplastics in our Great Lakes

Here in North America, when we think of freshwater, we often think of the Laurentian Great Lakes. They hold more than one fifth of the world’s freshwater, are the basis of billions of dollars in economic activity and are a point of pride for those living on their shorelines.

For the Indigenous peoples of Canada, the Great Lakes hold even more importance. There are more than 75 First Nations communities in the Great Lakes watershed, all of whom fish the waters for food or sport.

It is no secret, however, that the Great Lakes have had their share of ecological problems. Most have been caused by us, including the ongoing issues of nutrient-loading, invasive species like zebra and quagga mussels, tributary dams and reduced ice cover.

Recent research now shows the Great Lakes also contain microplastic pollution, with the highest concentrations in heavily urbanized areas, like Toronto and Detroit.

Plastic debris washed up on the shore of Lake Ontario, near Toronto (photo courtesy of Kennedy Bucci)

Another study found that a litre of sediment from the St. Lawrence River contained up to 1,000 spherical microplastics – on par with the world’s most polluted marine sediments.

Microplastics are now globally distributed in freshwater lakes and rivers. They’ve been found in North America, Europe and Asia.

Contaminated habitats, contaminated wildlife

Microplastics fill the digestive tracts of the wildlife that inhabit freshwater ecosystems.

In a Texas river basin, for example, 45 per cent of captured sunfish had reportedly consumed microplastics. Another study found that 12 per cent of gudgeons, a small bottom-dwelling fish, caught in a French stream had microplastics in their guts.

Closer to home, our lab has found that fish from the Great Lakes can have up to 40 microplastics in their digestive tracts. Many of these are microfibres – small strands of synthetic textiles, some of which come from our clothing.

In marine animals, microplastics can alter gene expression, cause inflammation in tissues and affect reproductive success. But we know much less about the effects in freshwater wildlife, which may be different than in marine animals. For example, marine fish drink water, whereas freshwater fish absorb water through their gills and skin; this may lead to different exposure concentrations of microplastics.

Although some studies have examined population- and community-level effects, most have focused on the effects on individual animals. As a result, evidence regarding the effects of microplastics on populations of animals are scarce. We need to ask how these pollutants affect survival, reproduction and the interactions between species in a community.

Our lab is beginning to do just that. For example, an ongoing study is comparing the effects of a range of microplastics found in Lake Ontario, and measuring their effects on freshwater fish survival, development and reproduction.

Calling all scientists

The oceans cover more than 70 per cent of our globe. Still, the biodiversity on land and in freshwater is more than five times that in the oceans. In addition, the global population relies on freshwater and terrestrial ecosystems for food, water and recreation. As such, microplastic research must include all ecosystems.

We are using plastic products at an unprecedented rate, and have already generated an estimated 6,300 metric tonnes of plastic waste. Although some of this is recycled, about 79 per cent is accumulating in landfills or the environment.

Moving forward, we must invest in gathering more scientific evidence about the sources, fate and effects of microplastics in terrestrial and freshwater ecosystems. At the same time, we know enough about plastic pollution to act.

As Canada takes presidency of the G7 this year, we applaud our government, which has committed to take leadership in preventing further contamination of the planet by plastic pollution.

Kennedy Bucci is a graduate student at the University of Toronto, and Chelsea Rochman is an assistant professor of ecology and evolutionary biology at the University of Toronto

This article was originally published on The Conversation. Read the original article.

U of T health-care collaborations share $3.5 million in new federal funding

noreen.rasbach — Thu, 22 Feb 2018 15:45:37 +0000

U of T health-care collaborations share $3.5 million in new federal funding

noreen.rasbach Thu, 02/22/2018 - 10:45

Cutline

Nataly Siqueira, a U of T postdoctoral student working with Professor Craig Simmons, shows federal officials a vial of nanoparticles that will be added to a living tissue valve replacement for infants prior to implantation (photo by Jennifer Robinson)

Jennifer Robinson

Topic

Our Community

Computer Science

Faculty of Applied Science & Engineering

Faculty of Dentistry

Faculty of Medicine

Institute for Biomaterials and Biomedical Engineering