Life in Plastic Ain’t so Fantastic

Guest post by Louis Vassos, MEnvSci Candidate in the Professional Masters of Environmental Science program at the University of Toronto-Scarborough

Much like the Buggles’ 1980 debut album, our material preferences are well within the age of plastic. Thanks to its light weight, durability, inertness, and low manufacturing costs, our use of plastics has increased dramatically since the mid-20^th century. From bottles and toys to car parts and electronics, there is seemingly no application beyond its reach. Despite its uses and benefits, it has come under increasing scrutiny by environmentalists in recent years. In this regard, we tend to think of larger-scale and more visible environmental impacts, such as accumulation in landfills and petrochemical use in manufacturing. There has also been a significant amount of research on plastic in marine environments, usually focused on larger debris known as macroplastics. Over the past decade, however, there has been increasing concern about a new type of plastic debris in our oceans. Though its presence was first highlighted in the 1970s, we are only just beginning to realize the impact of fragments known as microplastics. As their name would suggest, they are small pieces of plastic, typically measuring less than 5mm in diameter and sorted into two distinct classifications.

Primary microplastics are manufactured to be microscopically sized and are typically used in air blasting as a paint and rust remover, as well as in personal care products as an exfoliating scrubber. This latter use has risen sharply in cosmetics and facial cleansers since the 1980s, with plastic “microbeads” replacing natural materials such as pumice and ground almonds. Regardless of application they usually enter water bodies through drainage systems, and are easily able to pass through filtration systems at sewage treatment plants due to their small size.

Microbeads in toothpaste. Retrieved from: https://blog.nationalgeographic.org/2016/04/04/pesky-plastic-the-true-harm-of-microplastics-in-the-oceans/

Secondary microplastics arise from the breakdown of larger pieces of plastic debris on both land and in water. Larger debris will typically enter marine ecosystems directly or indirectly through careless waste disposal, often being transported through river systems. Sources of transfer include coastal tourism, extreme weather events, fishing, other marine industries, and accidental spillage during transportation. Over time, a culmination of processes such as exposure to UV radiation can reduce the debris’ structural integrity, causing brittleness, cracking, and yellowing. This in turn can lead to fragmentation through abrasion and waves, and fragments will gradually become smaller over time before reaching microplastic size (Cole et al, 2011).

As Eriksen et al (2014) have estimated, there is a minimum of 5.25 trillion plastic particles weighing 268,940 tons in the world’s oceans. Microplastics account for 92.4% of this mass, and their reach has been substantial. Because of their buoyancy and durability, they have the ability to travel long distances without degrading for years. Denser plastics (such as PVC) will sink and have the potential to reach coastal sediment (Andray, 2011). Other marine microplastics will end up trapped in ocean current systems known as gyres, the most famous grouping of which is the “Great Pacific Garbage Patch” in the North Pacific Gyre. Despite what the name would suggest, it is not an island-like mass of floating debris, but is more akin to an extensive “soup” of debris difficult to see with the naked eye. At a density of 334,271 pieces/km², microplastic mass in the area was found to be 6 times that of plankton (Moore et al, 2001). 

Potential microplastic transport pathways (From Wright et al, 2013)

Densities such as this increase potential microplastic ingestion by various marine organisms, especially filter feeders, plankton, and suspension feeders. These species may mistake debris for prey based on size or colour, or passively ingest them without being selective (Wright et al, 2013). In Farrell and Nelson’s (2013) study of mussel-eating crabs, they found that it is possible for microplastics to be transferred to individuals at a higher trophic level. The large surface area to volume ratio of microplastics makes them susceptible to water-borne pollutant contamination, and can cause toxic plastic additives such as BPA and PCB to leach into the water. This debris can also act as a dispersal vector for microbial communities, including potentially pathogenic species (Jiang et al, 2018). While the ingested debris can accumulate within individuals and be transferred up the food chain, the exact effects of this are not entirely known at this point in time (Avio et al, 2017). A recent study by Lei et al (2018), however, found that microplastics can cause oxidative stress and intestinal damage in zebrafish and nematodes, and that their toxicity is closely dependent on particle size.

Intestinal damage in zebrafish caused by exposure to 1.0 mg L^-1 of different microplastic types and sizes. Photograph A shows control (top), survival (middle), and dead after exposure (bottom) zebrafish (From Jiang et al, 2018)

Fluorescent microspheres on a crab’s gill lamella transferred from ingesting mussels, each measuring 5 micrometres in diameter (From Farrell and Nelson, 2013)

          What does the future hold for microplastics? Because their effects on both marine life and humans is relatively unknown, it is important to try and prevent them from entering and accumulating within marine environments. Properly dispose of larger plastic items to prevent them from entering waterways and breaking down into secondary microplastics, and be conscious about the presence of primary microplastics in other products. Make informed decisions when buying cosmetics, and choose ones that use natural exfoliating materials. Microbead bans have already begun to be enacted in several countries, including the UK, US, Canada and New Zealand (Pfeifer, 2018). There is also the potential for future studies on topics such as the health effects of microplastic ingestion and leached additives, debris behavior within the water column, and new standardized techniques for detection and sampling (Cole et al, 2011). It is hard to say what will happen next, but the removal of these 5.25 trillion particles from our oceans will prove to be a very difficult challenge without the development of novel extraction methods.

SOURCES

Anadrady, A.L. 2011. Microplastics in the marine environment. Marine Pollution Bulletin 62:1596 – 1605

Avio, C.G., S. Gorbi, and F. Regoli. 2017. Plastics and microplastics in oceans: from emerging pollutants to emerged threat. Environmental Research 128: 2 – 11

Cole, M., P. Lindeque, C. Halsband, and T.S. Galloway. 2011. Microplastics as contaminants in the marine environment: a review. Marine Pollution Bulletin 62:2588 – 2597

Eriksen, M., L.C.M. Lebreton, H.S. Carson, M. Thiel, C.J. Moore, J.C. Borerro. F. Galgani, P.G. Ryan, and J. Reisser. 2014. Plastic pollution in the world’s oceans: more than 5 trillion plastic pieces weighing over 250,000 tons afloat at sea. PLOS One

Farrell, P., and K. Nelson. 2013. Trophic level transfer of microplastic: Mytilus edulis (L.) to Carcinus maenas (L.). Environmental Pollution 177:1 – 3

Jiang, P., S. Zhao, L. Zhu, and L. Daoji. 2018. Microplastic-associated bacterial assemblages in the intertidal zone of the Yangtze Estuary. Science of the Total Environment 624:48 – 54

Lei, L., S. Wu, S. Lu, M. Liu, Y. Song, Z. Fu, H Shi, K. Raley-Susman, and D. He. 2018. Microplastic particles cause intestinal damage and other adverse effects in zebrafish Danio rerio and nematode Caenorhabditis elegans. Science of the Total Environment 619:1 – 8

Moore, C.J., S.L. Moore, M.K. Leecaster, and S.B. Weisberg. 2001. A comparison of plastic and plankton in the North Pacific Central Gyre. Marine Pollution Bulletin 42:1297 – 1300

Pfeifer, H. 2018. The UK now has one of the world’s toughest microbead bans. CNN. Retrieved from: https://www.cnn.com/2018/01/09/health/microbead-ban-uk-intl/index.html

Wright, S.L., R.C. Thompson, and T.S. Galloway. 2013. The physical impacts of microplastics on marine organisms: a review. Environmental Pollution 178:483 – 492

The problematic charismatics: Are loveable invasives getting a free pass?

Guest post by Will Brown, MEnvSci Candidate in the Professional Masters of Environmental Science program at the University of Toronto-Scarborough

In the world of animal conservation, charismatic wildlife - those loveable, huggable species like giant pandas or koalas - take centre stage. They’re the kinds of animals you see dominating news stories, books, and movies, with less-attractive species often falling by the wayside. The concept of charismatic species is tied closely to animal conservation and protection. And the public’s love and adoration for charismatic creatures plays an essential role in the success of conservation and awareness campaigns. As flagship species they become ambassadors and icons, rallying support and focusing the public’s attention (and money) on an environmental cause or conservation program.

Figure 1 A famous example of a charismatic species used as a flagship species for a conservation group, the World Wildlife Fund (WWF). (Source)

For many years, a societal bias for charismatics has been important for protecting and conserving rare and imperilled species. But what happens when a charismatic species, rather than requiring protection, is considered an invasive pest? And how does this affect the proper implementation of invasive species management and threat abatement?

A perfect example of a charismatic species as an invasive pest is wild horses, known as brumbies, in Australia. First introduced for farm work in 1788, there are now over 400 000 brumbies throughout the country. As an invasive this species causes erosion and damages vegetation with their hard hooves and overgrazing. They damage and foul waterholes and spread weeds through seeds carried in their dung, manes, and tails. As competitors with native species, they can force wildlife from favoured habitats and dominate food and water sources. There is a significant portion of the public, however, that see the brumby as an iconic Australian species that is  ’a unique equine and epitomizes the spirit of freedom’.

 

Figure 2 Feral horses threaten fragile ecosystems in Kosciusko National Park. (Source)

To manage the impacts of brumbies in Kosciuszko National Park, a plan was released in 2016 to reduce the number of wild horses by 90% over a 20-year period. The cull was to be carried out using humane control methods including trapping, fertility control and ground shooting rather than aerial shooting and roping. The management plan sparked angry protests and fierce opposition, despite warnings from scientists about the impacts of brumbies in the region. Even though government scientists declared that the horse population in the region severely degrade natural waterways and threaten fragile native alpine wildlife, hundreds of people protested the cull in Sydney and support groups downplayed the adverse effects brumbies have had on the environment. Lisa Caldwell of the Snowy Mountain Horse Riding Association was reported as saying ‘You've got to remember that the national park is 6,900 square kilometres…horses are not going to have a huge impact on those wetlands’ (www.abc.net.au).

Now almost 2 years on, backlash to the draft legislation has halted any form of management and a new amended management plan is in the works. It is reported that the amended plan includes less aggressive reduction of wild horses, with culling more likely to reduce the numbers to several thousand rather than just 600. To overcome Australia’s environment laws that require a more complete removal of wild horses, a ‘brumbies bill’ is being put forward to give recognition to the horses’ ‘cultural significance’, providing them with legal protection to remain in the park.

Now consider how an uncharismatic species is treated in a similar situation. The feral pig, generally perceived as dirty, disease-ridden and hated by farmers, also roams through Kosciuszko National Park and has very similar impacts on the environment. Feral pigs degrade natural areas through rooting up soils, grasslands and forest litter as they feed on native plants. They also spread a number of diseases and predate on a host of native animals including insects, frogs, snakes and small ground-nesting birds. Unlike brumbies however, their numbers are managed within in the park with almost no opposition.

 

Figure 3 Feral pigs populations are controlled in Australia with minimal public opposition. (Source)

In both cases there are two species found in the same location, negatively impacting the ecosystem in a similar way. For the uncharismatic species, management plans are carried out promptly and effectively. But for the charismatic species, it seems clear that societal bias can lead to strong resistance from the public and as a result, management efforts can be delayed or watered down.

And this pattern isn’t restricted to Australia. In Canada, introduced feral cats are the No.1 killer of birds, responsible for over 100 million bird deaths per year. Even with this information available, there is no widescale control programs for managing feral cat populations. In British Columbia, an exploding European rabbit population at the University of Victoria was responsible for extensive damage to fields, lawns and mature trees. When the university tried to implement a removal program, public outcry delayed efforts and the university ended up committing to using non-lethal methods for controlling the rabbit population. Meanwhile, less cute and fluffy invasive species such as America bullfrogs in BC have active population control programs with almost no objection from the public.

Based on these examples, it is clear there is a degree of favouritism when it comes to how invasive species are perceived and subsequently managed. With an obvious bias towards charismatic species, the power of public opinion can have significant impacts on invasive species control. This in turn has the potential to result in severe ecological consequences. Unfortunately, due to the complexity of the issue there is likely no single solution. The most impactful approach may be to increase the public’s awareness of the negative impacts of invasives with a focus on how these species may be damaging native wildlife. A more controversial approach may be to simply provide government scientists with greater decision-making power when it comes to wildlife management, especially for federally and state-owned lands. Adding to the complexity of the issue is how valuable are the cultural ecosystem services provided by charismatic invasives. Are the cultural benefits of invasive species as important as those provided by native species? This is an important question that should be addressed in evaluating the overall impacts caused by invasive species. Biases present in invasion biology are rarely discussed but the issues are clear. For the effective management of all invasive species, whether huggable or ugly, these biases should be recognised and carefully considered. 

Don't be Ranunculus... Little known plant behaviours

Guest post by Agneta Szabo, MEnvSci Candidate in the Professional Masters of Environmental Science program at the University of Toronto-Scarborough

Through the scientific study of plant behaviour, we continue to discover new ways in which plants interact with their environment in animal-like ways. Words like “listening”, “foraging”, and “parenting” may seem odd to associate with plants, and yet plants show evidence of all of these behaviours. Here are some of the many ways in which plants behave.

Listening

As it turns out, plants are listening! A study by Heidi Appel and Rex Cocroft published in 2014 describes their discovery that plants can detect their predators acoustically and ramp up their defenses as a response. Appel and Cocroft recorded the sound vibrations of caterpillars chewing on Mouse‑ear Cress leaves, and played these recorded vibrations to previously unaffected Mouse-ear Cress plants over several hours before allowing caterpillars to attack the plants. The researchers found that, compared to plants that were primed with recordings of silence, those who were primed with recordings of chewing produced much higher levels of the oils glucosinolate and anthocyanin, which are toxic to caterpillars. Furthermore, Appel and Cocroft found that the plants were able to distinguish the sound vibrations caused by chewing from recordings of wind or other insect noises.

In addition to listening for their predators, plants can also listen for water. In 2017, Monica Gagliano and her colleagues published a paper showing that the Garden Pea was able to locate water by sensing the vibrations generated by water moving inside pipes. Garden Pea seedlings were planted in pots shaped like an upside-down Y, and each arm of the pot was treated with different experimental conditions. When one arm was placed in a tray of water and the other was dry, plant roots grew towards the arm with water. Seems obvious enough. However, when one arm was placed above a tube with flowing water and the other was dry, the plant roots still grew towards the water, even though there was no moisture. When given a choice between a tray of water and the tube with flowing water, the Garden Pea seedlings chose the tray of water. This led Gagliano to hypothesize that plants may use sound vibrations to detect water at a distance, but that moisture gradients allow the plants to reach their target at close proximity.

Garden Pea water acoustics experimental set-up (Gagliano et al., 2017)

Foraging

Plant roots forage for food in a similar way to animals. In his 2011 review, James Cahill explores plant root responses to varying nutrient cues in the soil. Cahill explains that plant roots are responsive to both spatial and temporal nutrient availability. For example, when a nutrient patch is placed in the soil at a distance from the plant, there is a substantial acceleration in root growth in the following days. This growth is directed precisely towards the nutrient patch, and as the root approaches its target, the rate of growth slows as the nutrient patch is consumed. Furthermore, plants develop greater root biomass in richer nutrient patches, and they allocate more root biomass to patches with increasing nutrient levels.

Other foraging plants include the parasitic Dodder vine. This plant has no roots and lives off a host plant. In 2006, Consuelo De Moraes and her team published a study demonstrating that the Dodder plant uses scent, or volatile chemical cues, to locate and select its host plant. De Moraes experimentally planted Dodder seedlings between a Tomato and Common Wheat plant, the Tomato being its preferred host. Using a time lapse camera, De Moraes captured the circling movement of the Dodder plant as it approached both host options repeatedly, before settling on the Tomato plant 90% of the time. Through further experimentation by giving the Dodder seedlings a choice between the condensed chemical odour of the Tomato plant and a live Tomato that has been covered to prevent giving off odour, it was determined that the Dodder uses the chemical signals to select its host. Without being able to “smell” the live Tomato plant, the Dodder chose to attach to the vile containing the condensed chemical odour. 

Dodder vine attaching to a Tomato plant

(PBS, 2014: https://www-tc.pbs.org/wnet/nature/files/2014/09/Mezzanine_485.jpg)

Parenting

One of the most fascinating aspects of plant behaviour is parental care and kin recognition. Suzanne Simard’s work studying forests as a complex, interconnected organism has been featured on several popular media outlets including the TED Talk series and the Radiolab podcast. Through her research, Simard discovered that through a network of mycorrhizal fungi, adult trees were nurturing their young with a targeted exchange of nutrients such as carbon and nitrogen, as well as defense signals and hormones. Through experimental plantings of Douglas Fir seedlings that were directly related to the adult trees and unrelated Douglas Fir seedlings, she found that the “mother trees” recognized and colonized their kin with larger networks of mycorrhizal fungi, and sent more carbon to these seedlings. Furthermore, there was a reduction in root competition with the related seedlings. When injured, the adult trees sent large amounts of carbon and defense signals to their young, which increased the seedlings’ stress resistance.

Tree mycorrhizal network schematic 

(Medium, 2017: https://medium.com/ideo-colab/fungal-networks-connected-businesses-b38025ca7171)

Similar recognition of kin was observed by Susan Dudley and Amanda File in a 2007 paper. In this study, Dudley and File planted related “sibling” Sea Rocket plants together in pots, as well as unrelated “stranger” Sea Rocket plants together in pots. After several weeks, the roots were cleaned and assessed. The study found that kin groups allocated less biomass to their fine roots, while stranger groups grew larger roots in order to compete for resources. The same responses were not observed when kin and stranger groups were grown in isolated pots, which suggests that the mechanism for kin recognition was through root interactions.

Although we still don’t fully understand the mechanism by which plants process information, it is clear that the way plants interact with their environment is far more complicated than we previously thought. The concept of plants as inanimate organisms, blindly competing for resources is now outdated. Continued discoveries in plant behaviour demonstrate, once again, how little we understand about the natural environment—a humbling thought in an age when humankind thinks itself superior to our fellow species.

Bibliography

Appel, H.M. & Cocroft, R.B. (2014). Plants respond to leaf vibrations caused by insect herbivore chewing. Oecologia, (2014)175: 1257–1266.

Cahill, J.F. & McNickle, G.G. (2011). The behavioral ecology of nutrient foraging by plants. Annual Review of Ecology, Evolution, and Systematics, 2011(42): 289–311.

Dudley, S.A. & File, A.L. (2007). Kin recognition in an annual plant. Biology Letters (2007)3: 435–438.

Gagliano, M., Grimonprez, M., Depczynski, M. & Renton, M. (2017). Tuned in: plant roots use sound to locate water. Oecologia (2017)184: 151–160.

Runyon, J.B., Mescher, M.C. & De Moraes, C. (2006). Volatile chemical cues guide host location and host selection by parasitic plants. Science, 313(5795): 1964–1967.

Simard, S. (2016). Suzanne Simard: How trees talk to each other [Video file]. Retrieved from https://www.ted.com/talks/suzanne_simard_how_trees_talk_to_each_other#t-18444

Gained in translation: translational ecology for the Anthropocene

A recent evaluation of the state of science around the world run by 3M found that 86% of the 14,000 people surveyed believed that they knew 'little to nothing' about science. 1/3 of all respondents also said they were skeptical of science and 20% went farther, saying that they mistrust scientists and their claims.

Those attitudes wouldn't surprise anyone following US politics these days. But they're still troubling statistics for ecologists. Perhaps more than most scientific disciplines, ecologists feel that their work needs to be communicated, shared, and acted on. That's because modern ecology can't help but explicitly or implicitly include humans – we are keystone species and powerful ecosystem engineers. And in a time where the effects of global warming are more impactful than ever, and where habitat loss and degradation underlie an age of human-caused extinction, ecology is more relevant than ever.

The difficulties in converting primary ecological literature into applications are often construed as being caused (at least in part) by the poor communication abilities of professional scientists. Typically, there is a call for ecologists to provide better science education and improve their communication skills. But perhaps this is an 'eco-centric' viewpoint – one that defaults to the assumption that ecologists have all the knowledge and just need to communicate it better. A more holistic approach must recognize that the gap between science and policy can only be bridged by meaningful two-way communication between scientists and stakeholders, and this communication must be iterative and focused on relevance for end-users.

William H. Schlessinger first proposed this practice - called Translational Ecology (TE) - nearly 8 years ago. More recently an entire special issue in Frontiers in Ecology and the Environment was devoted to the topic of translational ecology in 2017. [The introduction by F. Stuart Chapin is well worth a read, and I'm jealous of the brilliant use of Dickens in the epigraph: “It was the best of times, it was the worst of times, it was the age of wisdom, it was the age of foolishness, it was the epoch of belief, it was the epoch of incredulity.”]

Although applied ecology also is focused on producing and applying ecological knowledge for human problems, translational ecology can be distinguished by its necessary involvement of the end user and policy. Enquist et al. (2017, TE special issue) note: "Ecologists who specialize in translational ecology (TE) seek to link ecological knowledge to decision making by integrating ecological science with the full complement of social dimensions that underlie today's complex environmental issues."

From Hallet et al. (2017, TE special issue)

The essential component of translational ecology is a reliance on people or groups known as boundary spanners, which are the key to (effectively) bridging the chasm between research and application. These people or organizations have particular expertise and skill sets to straddle the divide between "information producers and users". Boundary spanners are accountable to the science and the user, and generally enable communication between those two groups.

Boundary spanners likely have interdisciplinary backgrounds, and integrate knowledge and skills from ecology and biology, as well as disciplines such as anthropology, human geography, sociology, law, or politics. The key issue in that boundary spanners can overcome is the lack of trust between information users and producers. Translational ecology – through communication, translation, and mediation – is especially focused on developing relationships with stakeholders and boundary spanners are meant to be particularly skilled at this. 

For example, academics publish papers, and then the transmission of information to potential users is usually allowed to occur passively. At best, this can be slow and inefficient. At worst, potential end users lack access, time, and awareness of the work. Boundary spanners (including academics) can ensure this knowledge is accessibly by producing synthetic articles, policy briefs and white papers, by creating web-based decision-support tools, or by communicating directly with end users in other ways. A great example of existing boundary spanners are Coop extension offices hosted at US land grant universities. Coops are extensions of government offices (e.g. USDA) whose mission is to span the knowledge produced by research and to bring it to users through informal education and communication. 

For working academics, it may feel difficult to jump into translational ecology. There can be strong institutional or time constraints, and for those without tenure, fear that translational activities will interfere with other requirements. Institutions interested in working with ecologists also often face limitations of time and funding, and variable funding cycles can mean that boundary-spanning activities lack continuity.

But what's hopeful about the discussion of translational ecology in this issue is that it doesn't have an individualistic viewpoint: translational ecology requires teams and communities to be successful, and everyone can contribute. I think there is sometimes a very simplistic expectation that individual scientists can and must be exceptional generalists able to do excellent research, write and give talks for peers, teach and lecture, mentor, and also communicate effectively with the general public (in addition to taking care of administration, human resources, ordering and receiving, and laboratory management). We can all contribute, especially by training boundary spanners in our departments and labs. As F.S. Chapin says, "The key role of context in translational ecology also means that there are roles that fit the interests, passions, and skills of almost any ecologist, from theoreticians and disciplinarians to people more focused on spanning boundaries between disciplines or between theory and practice. We don't need to choose between translational ecology and other scientific approaches; we just need to provide space, respect, and rigorous training for those who decide to make translational ecology a component of their science." 

From Enquist et al. (2017, TE special issue).

References:
Special Issue: Translational ecology. Volume 15, Issue 10. December 2017. Frontiers in Ecology and the Environment

The Gender-Biased Scientist: Women in Science

Guest post by Maika Seki, MEnvSci Candidate in the Professional Masters of Environmental Science program at the University of Toronto-Scarborough

In November of 2017, Nature Ecology & Evolution published “100 articles every ecologist should read” by Courchamp and Bradshaw, sparking a social media outrage. Rightfully so, because the list of first authors only included two women. There remains a pervasive perception that women lack the skills to practice science, and that there simply are not enough women in the field for them to have made a significant contribution, referring to the male-dominated history of the sciences. Many of us have come across studies highlighting gender bias in science education - which people have attempted to use to explain gender gaps in STEM fields. However in 2011, neuroscientist Melissa Hines found no significant difference between the mathematical, spatial, and verbal skills of boys and girls. But of course that finding did not receive much attention. In light of the emerging discourse of vital inclusivity in science, now is the time to confront our own social biases with the goal of achieving gender equity in the scientific community.

Instead of rehashing these outdated arguments, why don’t we talk about the barriers that women face in science? Why don’t we talk about the sexism in the publishing and peer-review process? In 2015, evolutionary geneticist Fiona Ingleby submitted a research paper to PLOS ONE, where the peer-reviewer suggested that she work with male biologists in order to strengthen the study, stating, “It would probably … be beneficial to find one or two male biologists to work with (or at least obtain internal peer review from, but better yet as active co-authors).” The under-recognition of women scientists has been so rampant in the fabric of science that it has been coined the Matilda effect; named after the first women scientist to comment on the phenomenon, Matilda Jocelyn Gage.
   
Why don’t we talk about the barriers women face in accessing employment in science, even while possessing the same qualifications as their male counterparts? At Yale University, a study was conducted wherein over 100 scientists assessed a resume for a job posting. The only difference between the resumes were the names; half of them were given recognizably male names, and the other half recognizably female names. The resumes submitted under the female names were deemed significantly less competent and employable, and were offered lower salaries. Clearly there is work to be done.

And then there was Tim Hunt, a Nobel laureate who made outright sexist comments at the World Conference of Science Journalists stating, “Let me tell you about my trouble with girls … three things happen when they are in the lab … You fall in love with them, they fall in love with you and when you criticize them, they cry.” Twitter responded with the hashtag #DistractinglySexy, where women scientists shared unglamorous photos of them doing their research work. Hunt subsequently resigned from his honorary post at the University College-London. We may think that this is an exceptional and isolated event, but studies show that we are not immune to these kinds of social forces of gender discrimination, even if we like to think so — especially as scientists. These seemingly minor micro-aggressions translate to devastating and tangible effects, such as the gender pay gap. 

Photo by @STEPHEVZ43 on Twitter, as a response to Tim Hunt’s sexist comments.

-Source: http://www.bbc.com/news/blogs-trending-33099289

Within scientific fields, we like to pride ourselves in being as close to bias-free as possible with our empirical, quantitative, and reproducible data. But scientists are people, and as such, we must confront the cultural and social influences that may permeate our objectivity. As scientists, we do not like to admit to this. But if we are going to arrive as close to the truth as possible, we need to capitalize on the emerging discourse of gender issues in science.
    
As of 2015, Canadian women represented only 22% of the STEM workforce. Not only are women under-represented in the workforce despite 62% of undergraduate students being women, but they are under-compensated. According to Statistics Canada, the wage gap persists across all fields, with the women median income of a bachelor’s degree being $68,342, and $82,083 for men. This is not a “third world” problem. This is a global issue. It is indisputable that there are systemic barriers that women face when pursuing careers in science. So why can’t scientists consider the confounding social factors at play that create these patterns? In science when somebody denies a phenomenon after many analyses point to the same mechanism, we would likely consider that as being irrational. With this in mind, is the denial of gender bias in science not irrational? By acknowledging these biases and promoting change, we take aim at the lack of objectivity in the discipline of science. It should also be encouraged to confront the sexism, racism, and all other intersectionalities of power imbalance within the science community. Some may argue that there is no place for politics in science, but we must face the reality that the two can not be separated. Addressing the sexism would bring us better, more balanced science. 

Statistics Canada graph on the Canadian men and women in STEM fields.

-Source: http://www.macleans.ca/society/science/gender-inequality-in-the-sciences-its-still-very-present-in-canada/

How can we aspire towards a world of innovation and ground-breaking research when roughly half of the population is held back? And how can we address it? To start, we need to hold institutions more accountable. It is disheartening to know that had people not reacted to the all-male panels, it would not be seen as a problem. Furthermore, it is not enough to tweet about it. It’s a start, but not nearly enough — because how many of these types of stories repeat themselves in the media? We need it to be written in the mandates of institutions, and this is not enough. We need it to be enforced. We also need women to be more involved and hold power in these decision-making panels; it is not enough to throw in a token white woman and call it a day. It is not enough for women to be given a seat on the board as a corporate marketing tool under the guise of inclusivity. They must also be afforded the same power that men have. We need to hold each other more accountable. We need to confront our own prejudices, no matter how uncomfortable that may be. If not for women, then do it for practical and selfish reasons; do it because there are studies that show that women have to be more productive than men to be deemed equally scientifically competent (feeling the pressure to prove themselves). And do it because it is better for the economy, and because diversity in the workplace increases productivity

Graph by The Star on the income of full-time men and women in Canada, who have a bachelor’s degree.

-Source: https://www.thestar.com/news/canada/2017/11/29/gender-pay-gap-persists-census-data-shows.html

There is no good reason to continue to exclude women from the same influential roles that men have, and it is time that we each consider our own sexist views (whether sub-conscious or not). It is time to challenge the systemic biases in powerful institutions in order to let women claim their full potential as true peers to men; as colleagues, partners, scientists, and in all other walks of life. In order to increase scientific literacy, we can not afford to continue to exclude women from science, because science needs women. In the spirit of the United Nations’ International Day of Women and Girls in Science day, which passed on February 11^th, and International Women’s day today, let us commit to empowering women to reach political, social, and economic equality to men. And let us make changes in our own lives, begin conversations with those around us, and become more active in our communities to progress towards gender equity.

Moving on up to the regional scale

Like the blind men and the elephant, perspective drives understanding in ecology. The temporal and spatial scale of analysis (let alone the system and species you focus on) has major implications for your conclusions. Most ecologists recognize this fact, but consider only particular systems, scales or contexts due to practical limitations (funding, reasonable experimental time frames, studentship lengths). 

Ecologists have long known that regional processes affect local communities and that local processes affect regional patterns. Entire subfields like landscape ecology, metapopulations, metacommunities, and biogeography (species area relationships) highlight these spatial dependencies. But high-profile ecological research into biodiversity and ecosystem functioning ('BEF') primarily considers only local communities. Recently though, the literature has started to fill this gap and asking what BEF relationships look like at larger spatial scales, and how well local BEF relationships predict those at larger spatial scales.

'Traditional' BEF experiments were done at relatively small spatial scales (often only a few meters^2). Positive BEF relationships were commonly observed, but often were quite saturating – that is, only a few species were necessary to optimize the function of interest. If the impact of biodiversity saturates with only a few species, it would seem that surprisingly few species are necessary to maintain functioning. True, studies that considered multiple ecosystem functions are more likely to conclude that additional diversity is required for optimal functioning (e.g. Zavaleta et al. 2010). But a simplistic evaluation of the facts that a) ecosystem functioning rapidly saturates with diversity, and b) locally, diversity may not be generally decreasing (Vellend et al. 2017), could lead to overly confident conclusions about the dangers of biodiversity loss. Research on BEF relationships, as they transition from local to larger spatial scales, is increasingly suggesting that our understanding is incomplete, and that BEF relationships can grow stronger at large spatial scales.

A number of recent papers have explored this question, and in considering the essential role of spatial scale. Predictions about how BEF relationships will change with spatial scale vary. On one hand, in most systems there are only a few dominant species and these species may disproportionately contribute to ecosystem functions, regardless of the spatial scale. On the other hand, species-area relationships tend to increase rapidly at small scales, as community composition turns over. If that is the case, then different species may make important contributions in different places. Winifree et al. (2018) contrasted these predictions for three crop species that rely on natural bee pollinators (cranberries, blueberries, and watermelons). They censused pollinators at 48 sites, over a total extent of ~3700 km^2. Though at local scales very few bee species were required to reach pollination goals, the same goals at larger spatial scales required nearly an order of magnitude more bee species. These results in particular appeared to be driven by species turnover among sites--perhaps due to underlying environmental heterogeneity.

From Winifree et al. "Cumulative number of bee species required to maintain thresholds of 25% (orange), 50% (black), and 75% (purple) of the mean observed level of pollination, at each of n sites (16). Horizontal dashed lines indicate the total number of bee species observed in each study. Error bars represent 1 SD over all possible starting sites for expanding the spatial extent. For all three crops combined, each x-axis increment represents the addition of one site per crop".

Another mechanism for increased BEF at larger scales is insurance effects. The presence of greater diversity can interact with spatial and temporal environmental variation to increase or stabilize ecosystem functioning. Greater diversity should maximize the differential responses of species to changing conditions, and so buffer variation in ecosystem functioning. Such effects, when they occur through time are temporal insurance, and when they occur via dispersal among sites, spatial insurance. Wilcox et al. (2018) considered the role of synchrony and asynchrony among populations, communities, and metacommunities to ask whether local asynchrony affected stability (see Figure below for a nice conceptual explanation). Across hundreds of plant data sets, they found that asynchrony of populations did enhance stability. However, the degree to which it affected stability varied from very weak to very important (e.g. by 1% to 300%). Maximizing species or population differences at local scales apparently can have implications for dynamics, and so potentially stability of functioning, at much larger scales.

From Wilcox et al. "Conceptual figure showing how stability and synchrony at various spatial scales within a metacommunity combine to determine the stability of ecosystem function (here, productivity). In (a), high synchrony of species within and among local communities results in low stability at the scale of the metacommunity. In (b), species remain synchronised within local communities, but the two communities exhibit asynchronous dynamics due to low population synchrony among local patches. This results in relatively high gamma stability. Lastly, in (c), species exhibit asynchronous dynamics within local communities through time, and species-level dynamics are similar across communities (i.e. high population synchrony). This results in relatively high gamma stability. Blue boxes on the right outline stability components and mechanisms, and the hierarchical level at which they operate. Adapted from Mellin et al. (2014)."

Finally, Isbell et al. (2018) describe ways in which ecosystem functioning and other contributions of nature to humanity are scale-dependent, laying out the most useful paths for future work (see figure below).

From Isbell et al. 2018.

These papers make nearly identical points worth reiterating here: 1) we have done far too little work beyond the smallest spatial scales (~3 m^2) and so lack necessary knowledge of the impacts of losing of biodiversity, and 2) policy decisions and conservation activities are occurring at much larger scales – at the scale of the park, the state, or the nation. Bridging this gap is essential if we are to make any reasonable arguments as to why ecosystem function figure into  large-scale conservation activities.

References:
Sustaining multiple ecosystem functions in grassland communities requires higher biodiversity. Erika S. Zavaleta, Jae R. Pasari, Kristin B. Hulvey, G. David Tilman. Proceedings of the National Academy of Sciences Jan 2010, 107 (4) 1443-1446; DOI: 10.1073/pnas.0906829107. 

Plant biodiversity change across scales during the Anthropocene. Vellend, Mark, et al. Annual review of plant biology 68 (2017): 563-586.

Species turnover promotes the importance of bee diversity for crop pollination at regional scales. RACHAEL WINFREE, JAMES R. REILLY, IGNASI BARTOMEUS, DANIEL P. CARIVEAU, NEAL M. WILLIAMS, JASON GIBBS. SCIENCE16 FEB 2018 : 791-793

Asynchrony among local communities stabilises ecosystem function of metacommunities. Kevin R. Wilcox, et al. Ecology Letters. Volume 20, Issue 12, Pages 1534–1545.

Isbell, Forest, et al. "Linking the influence and dependence of people on biodiversity across scales." Nature 546.7656 (2017): 65.

A general expectation for the paradox of coexistence

There are several popular approaches to the goal of finding generalities in ecology. One is essentially top down, searching for generalities across ecological patterns in multiple places and at multiple scales and then attempting to understand the underlying mechanisms (e.g. metabolic scaling theory and allometric approaches). Alternatively, the approach can be bottom up. It may consider multiple models or multiple individual mechanisms and find generalities in the patterns or relationships they predict. 

A great example of generalities from multiple models is in a recent paper published in PNAS (from Sakavara et al. 2018). It relies on, links together, and adds to, our understanding of community assembly and the effects of competition on the distribution of niches in communities. In particular, it adds additional support to the assertion that both combinations of either highly similar or highly divergent species can coexist, across a wide variety of models.

Work published in 2006 by Scheffer and van Nes played an important early role towards a reconciliation of neutral theory and niche-based approaches. They used a Lotka-Volterra model to highlight that communities could assemble with clusters of coexisting, similar species evenly spaced along a niche axis (Figure 1). Neutrality, or at least near-neutrality, could result even when dynamics were determined by niche differences. [Scheffer, van Nes, and Remi Vergnon also provide a nice commentary on the Sakavara et al. paper found here].

Fig. 1: From Scheffer and van Nes, emergent 'lumpiness' in communities.

One possibility is that Scheffer and van Nes's results might be due to the specifics of the L-V model rather than representing a general and biologically realistic expectation. Sakavara et al. address this issue using a mechanistic consumer-resource model in "Lumpy species coexistence arises robustly in fluctuating resource environments". Under this model, originally from Tilman's classic work with algae, coexistence is limited by the number of resources that limit a species' growth. For 2 species, for example, 2 resources must be present that limit species growth, and further the species must experience a tradeoff in their competitive abilities for the 2 resources. Coexistence can occur when each species is limited more by the resource on which it is most competitive (Figure 2). Such a model– in which resources limit coexistence—leads to an expectation that communities will assemble to maximize the dissimilarity of species.

Fig 2. From Sakavara et al. (2017).

Such a result occurs when resources are provided constantly, but in reality the rates of resource supply may well be cyclical or unpredictable. Will community assembly be similar (resulting in patterns of limiting similarity) when resources are variable in their supply? Or will clumps of similar species be able to coexist? Sakavara et al. considered this question using consumer-resource models of competition, where there are two fluctuating limiting resources. They simulated the dynamics of 300 competing species, which were assigned different trait values along a trait gradient. Here the traits were the half-saturation coefficients for the 2 limiting resources: these were related via a tradeoff between the half saturation constants for each resource.

What they found is strikingly similar to the results from Scheffer and van Nes and dissimilar to the the results that emerge when resources are constant. Clumps of coexisting species emerged along the trait axis. When resource fluctuations occurred rapidly, only fairly specialized species survived in these clumps (R* values that were high for either resource 1, or resource 2, rather than intermediate). But when fluctuations were less frequent, clusters of species also survived at intermediate points along the trait axis. However, in all cases the community organized into clumps composed of very similar species that were coexisting (see Figure 3). It appears that this occurs because the fluctuating resources result in the system having non-stationary conditions. That is, similar sets of species can coexist because the system varies between those species' requirements for persistence and growth. 

Fig. 3. "Lumpy species coexistence". The y-axis shows the trait value (here, the R*) of species present under 360 day periodicity of resource supply.  

Using many of the dominant models of competition in ecology, it is clearly possible to explain the coexistence of both similar or dissimilar species. This is true across approaches from the Lotka-Volterra results of Scheffer and van Nes, to Tilman's R* resource competition, to Chessonian coexistence (2000). It provides a unifying expectation upon which further research can build. Perhaps the paradox of the planktons is not really a paradox anymore?

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Reference:
Athanasia Sakavara, George Tsirtsis, Daniel L. Roelke, Rebecca Mancy, and Sofie Spatharis. Lumpy species coexistence arises robustly in fluctuating resource environments. PNAS 2017; published ahead of print December 20, 2017, doi:10.1073/pnas.1705944115