The “man” in mangroves: How does the Anthropocene impact biodiversity in these ecosystems?

 *This post is by Nina Adamo, a student in Marc's 'Causes and COnsequences of Diversity' class.

Mangroves are among the most biologically important forest ecosystems on Earth, found in the intertidal zone between land and sea along tropical and subtropical coasts around the world.⁷ Mangrove ecosystems provide habitat for a wide range of terrestrial as well as aquatic organisms including plants, fish, mollusks, birds, reptiles, and crustaceans, among many others.¹

Mangroves also serve as nursery habitats for various fish and crab species found in coastal regions, as mangroves provide high abundances of food and shelter for developing wildlife living in coastal regions.⁷ Since many species use mangroves as nursery grounds, fish diversity and abundance in neighbouring coastal ecosystems has been positively linked to the proximity of mangrove areas, suggesting that mangrove habitat is critical in supporting biodiversity in surrounding coastal ecosystems.⁵

Figure 1: Many species such as fish and crustaceans use mangroves as a nursery site for their young, where shelter from predators and food is abundant.⁹

Along with supporting a wide range of biodiversity along coastal ecosystems, mangroves also provide many essential ecosystem services to humans. Some of these societal benefits include natural resources such as fish and timber, coastal protection from storms, and assisting in mitigating climate change by removing carbon dioxide from the atmosphere and storing it.¹¹

Despite the critical role mangroves play in supporting coastal biodiversity and providing ecosystem services to society, mangroves have been disappearing globally at an alarming rate of 1-2% per year due to anthropogenic activities and accelerated global climate change.⁴ The main threats to these ecosystems are rising sea levels causing coastal erosion, environmental condition changes due to climate change, land-use changes, deforestation, and overexploitation of natural resources.⁴ This has led to the loss of about 50% of mangrove coverage across the globe since 1950.¹⁰

In recent years, there have been a great number of studies that have explored the impacts of anthropogenic activities and climate change on the biodiversity of vegetation, benthic meiofauna, and benthic fauna found in mangrove ecosystems.

Figure 2: A stilt mangrove tree in a mangrove forest coastal ecosystem on an island in East Kalimantan, Indonesia.⁸

In the Sundarbans, which is the world’s largest remaining natural mangrove ecosystem located on the border of Bangladesh and India, there has been a homogenization of tree species composition over the span of 28 years from the 1980s to the 2010s.¹⁰ In other words, the largest remaining mangrove ecosystem has experienced a loss in community biodiversity of mangrove plant species over time due to anthropogenic activities and the environmental impact of climate change.

The loss of biodiversity in ecosystems is a crucial issue because higher biodiversity in most ecosystems typically leads to higher ecosystem functioning, so if biodiversity is lost through stressors such as habitat loss or extreme environmental conditions such as those produced through global climate change, it could have severe impacts on the diversity of an ecosystem and hence the functioning of the ecosystem as a whole.²

The biodiversity of benthic meiofauna, which are very small invertebrates that live in the bottom of aquatic mangrove ecosystems, are also negatively impacted by anthropogenic disturbances. In a comparison study of disturbed and undisturbed mangrove areas, disturbed areas displayed a 20% loss of benthic meiofauna biodiversity compared to undisturbed mangrove areas.² Since many juvenile fish species that use mangrove ecosystems as nursery grounds rely heavily on meiofauna for food, this loss of biodiversity through anthropogenic causes could cause a reduction in ecosystem functioning not only within mangrove communities but in surrounding coastal ecosystems as well.²

A similar observation is also found with the biodiversity of benthic fauna in mangrove ecosystems in the Philippines, where protected mangrove ecosystems have significantly higher diversity and abundance of crab species than reforested mangrove ecosystems that have been disturbed by humans.¹ This suggests that environmental factors influenced by climate change and human influences in mangrove ecosystems can have a negative impact on the biodiversity of benthic fauna, one of the most dominant groups in these systems, which could impair the overall functioning of the ecosystem.¹

With the increasing loss of mangrove habitat and the biodiversity within it across the globe due to anthropogenic activities and climate change, it is essential that humans intervene with utilizing other paradigms such as the flagship species paradigm to increase mangrove conservation and policies to protect mangrove habitat,¹¹ well-researched and well-managed mangrove planting restoration,⁶ and more research on innovative manmade artificial mangroves that may help to restore these ecosystems.³

Figure 3: Locations of the various megafauna found in mangroves (locations of mangrove areas shown in green) around the globe, with the orange representing terrestrial and the blue representing aquatic megafauna. Some examples of megafauna found in mangroves (from top-left to bottom-left in a clockwise direction) include the Key deer, Manatee, Sailfin lizard, Sawfish, Three-toed sloth, Spotted deer, Bengal tiger, Otter, Green turtle, Crocodile, and the Proboscis monkey.¹¹

The focus of much of the recent research on mangrove conservation has utilized an ecosystem services approach, where the benefits that mangroves provide to humans is stressed as an incentive for conservation.¹¹ For this reason, most of the research has been focused on smaller benthic invertebrates such as crabs and shrimp, rather than larger charismatic megafauna that are found in mangroves around the world such as sloths, Bengal tigers, green turtles, and proboscis monkeys.¹¹

Conservation awareness of mangrove ecosystems could be improved by using the flagship species paradigm which uses larger charismatic species found in mangrove ecosystems in marketing campaigns that would protect the entire ecosystem in which they are found. Since charismatic megafauna have been observed in mangrove habitats across the globe, using the flagship species paradigm in conjunction with the ecosystem services paradigm could increase public awareness of the threats facing these extremely diverse and productive ecosystems.¹¹

Conserving mangrove ecosystems around the world is important as these ecosystems provide ecosystem services to human society and play a critical role in supporting biodiversity within mangrove systems and in neighbouring coastal systems. With the increasing threat of anthropogenic activities and global climate change, the conservation and protection of mangroves is essential to reduce the decline in ecosystem functioning and biodiversity in these ecologically important ecosystems that many animals and humans alike rely on in order to live productive and successful lives.

References

1.     Bandibas, M. B., & Hilomen, V. V. (2016). Crab biodiversity under different management schemes of mangrove ecosystems. Global Journal of Environmental Science and Management, 2(1), 19–30. https://doi.org/10.7508/gjesm.2016.01.003

2.     Carugati, L., Gatto, B., Rastelli, E., Lo Martire, M., Coral, C., Greco, S., & Danovaro, R. (2018). Impact of mangrove forests degradation on biodiversity and ecosystem functioning. Scientific Reports, 8(1), 1–11. https://doi.org/10.1038/s41598-018-31683-0

3.     Florida Atlantic University. (2018). Humanmade mangroves could get to the “root” of the problem for threats to coastal areas. ScienceDaily. Retrieved February 20, 2020, from https://www.sciencedaily.com/releases/2018/08/180829115627.htm

4.     Hapsari, K. A., Jennerjahn, T. C., Lukas, M. C., Karius, V., & Behling, H. (2019). Intertwined effects of climate and land use change on environmental dynamics and carbon accumulation in a mangrove-fringed coastal lagoon in Java, Indonesia. Global Change Biology. https://doi.org/10.1111/gcb.14926

5.     Henderson, C. J., Gilby, B. L., Schlacher, T. A., Connolly, R. M., Sheaves, M., Flint, N., Borland, H. P., & Olds, A. D. (2019). Contrasting effects of mangroves and armoured shorelines on fish assemblages in tropical estuarine seascapes. Ices Journal of Marine Science, 76(4), 1052–1061. https://doi.org/10.1093/icesjms/fsz007

6.     Kodikara, K. A. S., Mukherjee, N., Jayatissa, L. P., Dahdouh‐Guebas, F., & Koedam, N. (2017). Have mangrove restoration projects worked? An in-depth study in Sri Lanka. Restoration Ecology, 25(5), 705–716. https://doi.org/10.1111/rec.12492

7.     Nagelkerken, I., Blaber, S. J. M., Bouillon, S., Green, P., Haywood, M., Kirton, L. G., Meynecke, J.-O., Pawlik, J., Penrose, H. M., Sasekumar, A., & Somerfield, P. J. (2008). The habitat function of mangroves for terrestrial and marine fauna: A review. Aquatic Botany, 89(2), 155–185. https://doi.org/10.1016/j.aquabot.2007.12.007

8.     Rante, A. (2019, December 12). A stilt mangrove tree in a protected area on Semama Island in East Kalimantan. Supertrees: Meet Indonesia’s mangrove, the tree that stores carbon. [Image].Vox. Retrieved February 20, 2020 from https://www.vox.com/2019/12/12/21009910/climate-change-indonesia-mangroves-palm-oil-shrimp-negative-emissions-blue-carbon

9.     Rante, A. (2019, December 12). In the water lapping at mangrove roots, young fish and plankton take refuge from predators. Supertrees: Meet Indonesia’s mangrove, the tree that stores carbon. [Image].Vox. Retrieved February 20, 2020 from https://www.vox.com/2019/12/12/21009910/climate-change-indonesia-mangroves-palm-oil-shrimp-negative-emissions-blue-carbon

10.  Sarker, S. K., Matthiopoulos, J., Mitchell, S. N., Ahmed, Z. U., Mamun, Md. B. A., & Reeve, R. (2019). 1980s–2010s: The world’s largest mangrove ecosystem is becoming homogeneous. Biological Conservation, 236, 79–91. https://doi.org/10.1016/j.biocon.2019.05.011

11.  Thompson, B. S., & Rog, S. M. (2019). Beyond ecosystem services: Using charismatic megafauna as flagship species for mangrove forest conservation. Environmental Science & Policy, 102, 9–17. https://doi.org/10.1016/j.envsci.2019.09.009

Intellectual death by a thousand cuts

My business is thinking. Let me be a little less succinct. My profession as a Professor of Biology is my passion, and I am fortunate enough to be paid to think about how the natural world works and to come up with possible solutions to global problems. I was trained to do this and my past training (all 11 years) and my current salary are paid by taxpayers to do this. This all seems rather straightforward, but yet why does it feel like the universe is conspiring to prevent this intellectual work from being done?

As pointed out brilliantly by Cal Newport in the Chronicle of Higher Education, in an article titled “Is E-mail Making Professors Stupid?”, Professors are being buried under a pile of administrative work at the expense of intellectual pursuits. The amount of time and effort spent on managing people and money, sitting on departmental/university committees, representing the university externally, and applying for research funds and awards have all increased significantly over time. Professors are increasingly being converted into middle managers, the victims of a culture of bureaucratization and downloading.

At the organizational level, this all makes sense. The necessary regulatory obligations and internal checks and balances are very robust, and appear, to outside scrutiny, as though tax-payer funds are being used correctly and efficiently. However, the reality is that university bureaucracies have grown substantially over the past couple of decades while student enrollment and faculty numbers at many institutions has been stagnant or even declining. And a byproduct of this increased bureaucracy has been an increase in internal programs and procedures that require communication and paperwork.

This increase in internal communication and administration has been paired with increasing external demands for professors’ time. Increasing requests to perform grant and manuscript reviews, participate in panels, pressure to include outreach and knowledge mobilization in research projects, and the inundation of predatory journals and conference requests have been experienced by all researchers.

All these forces conspire to eat away at the ability for professors to do the thing they are actually paid to do –literally the death of the intellectual by a thousand cuts. If I were to properly answer all of the e-mails I receive, I would be spending 3+ hours a day doing this one task. Not to mention meetings. Professors spend much more of their time in meetings today than a generation ago. I just looked at the next week in my calendar (an uneventful week by my standards), and there are 14 hours of meetings scheduled. I also need to schedule these meetings myself an increasingly frustrating activity that requires multiple attempts. So e-mail and meetings alone would amount to about 25-32 hours a week.

 

What should I be doing with my time? Well, working on manuscripts (my students and my own), editing and reviewing for journals, writing grant proposals, teaching, participating in student committees, data analyses, research projects and training, and reading are all necessary. My estimation of the time needed to optimize these, or at least do a minimally acceptable job, would be about 30 hours a week. So, either I work a minimum of 60 hours a week, or something has to give. I am fortunate that I have the resources to hire a lab manager and do not need to deal with lab management and ordering supplies, etc., which would require an additional 4-8 hours a week.

At the moment I am faced with a dichotomous decision, work evenings and weekends or purposefully prioritize certain activities over others. And to the frustration of colleagues and administrators, e-mail tends to the bottom of the priority list. But this cost of bureaucratization should not be burdened by professors alone.

Cal Newport highlights several mechanisms to relieve this burden in his article. Minimally, professors should schedule e-mail time, like one hour a day. And, filed under “do as I say, not as I do”, professors should say 'no' to many of the unsolicited requests that pull them away from their core responsibilities. Yet institutions have a role to play. Newport suggests that Professors require executive assistants to manage e-mail correspondence, scheduling and paperwork and these should come with their positions (not one to one, perhaps shared amongst groups of faculty). Since professors routinely work extra hours to stay on top of all the demands, they should start to be compensated for this additional work. Further, there should be an agreed upon fixed amount of administrative service they are required to do (e.g., 10 hours a week), and going beyond this should require teaching buyouts or other forms of compensation (e.g., funds for assistant).

While the onslaught of demands seems so overwhelming, there are solutions. They just need to be pursued and pushed to university administrations.

Life isn't all Rainbows and Butterflies...

Guest post by Carolyn Thickett, MSc. Candidate at the University of Toronto-Scarborough

Life isn't all Rainbows and Butterflies...

… especially in an age of extreme habitat loss, chemical pollution, invasions by alien species and climate change. All of these pressures are contributing to the dramatic decline of insects currently being observed all around the world.

In Canada, the general public is responding by trying to contribute their time and knowledge in any way that they can. Citizen Science programs encourage people with little or no previous experience to participate by working with staff from one of the conservation areas in the Greater Toronto Area. These programs are aimed at engaging the general public in conservation efforts for the purpose of education, but with the added benefit of reducing the cost of expensive conservation work.

Many more events are happening out of the public eye, not advertised, even held in secret. I attended one such event this past June, held in an undisclosed location, in Eastern Ontario. This was an invitation-only event, attended by a consortium of people concerned about the status of the Mottled Duskywing Butterfly in Ontario, spearheaded by butterfly enthusiast Jessica Linton.

Mottled Duskywing Butterfly. Photo: Carolyn Thickett

Dr. Gard Otis, a bee and butterfly researcher from the University of Guelph, is unveiling new
information about these specialist butterflies and their unique habitat requirements. The Mottled Duskywing depends on New Jersey Tea (Ceanothus americanus), a plant that is common to alvars as well as sandy soils supporting oak savannas, a critically endangered habitat in Canada. Land management issues related to the preservation and restoration of grassland habitats, such as oak savannas, must then be included in the Mottled Duskywing recovery strategy.

One of those issues is fire suppression, originally put into practice due to the inherent risk to
property and human lives. The suppression of fire over time promotes plant succession, which is the process by which grasslands turn into shrublands, then into thickets and eventually into forests. Succession is detrimental to New Jersey Tea. It is a grassland plant that requires full sun and is unable to compete with the increasing canopy density of a forest. But what if fire wasn’t suppressed? Wouldn’t New Jersey Tea burn too?

As it turns out, New Jersey Tea is not only tolerant of fire, but it produces vigorous growth shortly after a fire disturbance (Throop & Fay, 1999). So, there is a threatened population of butterflies… living in a rare habitat… and scientists are setting it on fire?? Yup. It’s called prescribed burning.

But how do the butterflies survive such a disturbance? Sites are burned in sections, creating a patchwork of habitat with some portions left for conditions required by the butterflies. Some research by Swengel and Swengel (2007) suggests that some permanent unburned areas within the landscape may be important for specialist Lepidopterans, such as the Mottled Duskywing and the Karner Blue Butterfly (Lycaeides melissa samuelis), which is extirpated in Canada. Additionally, fire can provide many benefits which can even outweigh the risks. Recent work by Henderson et al. (2018) shows the short-term positive effect on another grassland butterfly to prescribed fire regimes. The diagrams below illustrate the results of their study and show the positive benefit derived from regular, and even frequent, burns.

Dr. Otis and myself walked transects through specific locations within the landscape, recording the location of each Mottled Duskywing that we encountered, the quantity of New Jersey Tea plants and keeping tally of the totals. Dr. Otis’ study will examine how Mottled Duskywings respond to the prescribed burns by utilizing different portions within the landscape. The next prescribed burn will occur early next spring by property staff, then the butterfly populations will again be assessed and compared with the baseline data.

In addition, staff at the Cambridge Butterfly Conservatory are currently working on determining the caterpillar rearing requirements of a related species, the Wild Indigo Duskywing. At this point they have had success getting females to lay eggs in captivity and rearing the larvae. The knowledge gained with the Wild Indigo Duskywings will be applied to the Mottled Duskywings, working towards reintroduction to one or more sites where they used to occur within the province, perhaps as early as 2020.

The Mottled Duskywing butterfly population we surveyed is the largest in Canada. At the end of the count, we received word that 4 teams of observers recorded 210 butterflies. This was great news for the researchers as the population appears to be stable, although the true population can only be determined through a detailed mark-recapture study which is tentatively being planned for summer 2019.

Mottled Duskywing conservation is gaining momentum… work has already started on habitat recovery and caterpillar rearing protocols. The information gathered and recovery actions taken could have implications for many other native prairie and grassland species. The same can be said for every other count, assessment, or restoration event. Whether you are a researcher or a concerned citizen, get involved. Know that your efforts could have massive implications for biodiversity, you could even SAVE a species from extinction!

To get involved in conservation, visit citizen science.

For more information on Mottled Duskywing butterflies, read the recovery strategy.

References

Fickenscher, J.L., Litvaitis, J.A., Lee, T.D. & Johnson, P.C. Insect responses to invasive shrubs:
Implications to managing thicket habitats in the northeastern United States. Forest Ecology
and Management 322 (complete), 127-135 (2014).

Henderson, Richard A., Meunier, Jed, & Holoubek, Nathan S. Disentangling effects of fire,
habitat, and climate on an endangered prairie-specialist butterfly. Biological Conservation 218
(complete), 41-48 (2018).

Swengel, A. B. & Swengel, S. R. Benefit of permanent non-fire refugia for Lepidoptera
conservation in fire-managed sites. Journal of Insect Conservation 11, 263–279 (2007).

Throop, Heather L. & Fay, Philip A. Effects of fire, browsers and gallers on New Jersey tea
(Ceanothus herbaceous) growth and reproduction. The American Midland Naturalist 141 (1),
51 (1999).

Amphibian Chytrid Crisis: A Deep Dive into a Deadly Disease

Guest post by Tristan Williams, MEnvSc Candidate at the University of Toronto-Scarborough

We currently live in an era of mass extinction, where many species around the world are at high risk of being lost forever, and among these species, amphibians are at much higher risk of extinction than any other (Wake and Vrendenburg, 2008). This comes from a combination of many factors, including climate change, habitat destruction and human land use, the presence of invasive species, and as we’ll be looking at here: the fungal infection chytridiomycosis.

Chytridiomycosis is a skin disease caused by a chytrid fungus, either Batrachochytrium dendrobatidis (Bd), or Batrachochytrium salamandrivorans (Bsal). Though these fungi may be small, they are a big deal when it comes to the health and stability of amphibian populations. They have been implicated for the heavy decline or even outright extinction of a large number of amphibian species, making it potentially the most impactful wildlife disease known (Scheele et al., 2014). These fungi have a number of traits that make it easy for them to spread to amphibians. One such trait is the ability to reside within a host without causing infection, using it as a reservoir from which it can spread to more vulnerable species (Fisher, 2017). This can be seen in the example of the midwife toad and alpine newt, which are carriers for Bsal, and can lead to infection of fire salamander populations.

Figure 1: Potential pathways for the spread of Bsal in Europe, from Fisher 2017.

The zoospores of these fungi also have two forms which contribute to their spread among amphibian population. The first is the motile aquatic form, which allows them to establish infection during the tadpole stage (Fisher, 2017). The second is the non-motile form, called an encysted spore, which has a thick cell wall, and are highly resilient. These encysted spores are capable of persisting in the environment while retaining their infectiousness, without needing a host at all for a long period of time. And if that wasn’t enough, it could be the case that birds can act as carriers for these encysted spores, bringing the fungus to new locations and further contributing to the spread of disease over larger distances. As noted by Fisher et al. (2017), it really does seem like amphibians really are in peril from a perfect pathogen. But what exactly do these fungal infections do to amphibians that make it such a problem?

Amphibians are cutaneous respirators. They “breathe” through their skin, allowing them to maintain the correct osmotic balance of electrolytes and water within the body. This is what makes chytrid fungi such a unique threat to amphibians. To other organisms the development of a cutaneous chytrid infection is usually not a big deal, but to amphibians it can directly interfere with their ability to respire (Voyles et al., 2009). The ensuing loss of electrolytes impairs the ability of the heart to function, blood flow to the rest of the body is reduced, and cardiac arrest leads to death as a result of complete collapse of the circulatory system. However, even before that occurs, the now physically impaired and lethargic individual is likely to become a victim of predation or a combination of other stressors as well. As an example of the potential severity of this disease, fire salamanders in the Netherlands that were infected with Bsal experienced a mortality rate of over 96% (Fisher, 2017). A very morbid and unfortunate situation our amphibian friends find themselves in.

Normally, the mucus layer present on the skin of amphibians contains a number of antimicrobial peptides and lysozymes, as well as symbiotic bacteria which all contribute to innate defenses against invading pathogens (Rollins-Smith et al., 2011). Amphibians have also shown to be capable of developing an acquired immune response to chytrid fungi after exposure, with some even developing Bd specific antibodies. So then why is chytridiomycosis such a problem for amphibians? The answer appears to be because chytrid fungi are capable of suppressing immune responses in many species before these defenses are capable of protecting against infection (Ellison et al., 2014). Other environmental stressors can also interfere with the ability of amphibians to mount an appropriate immune defense. Lack of food resources, temperature stress, or exposure to chemicals like pesticides can all increase the likelihood of fungal infection (Rollins-Smith et al., 2011). Furthermore, the amphibian life cycle itself can impair the ability of an individual to resist infection. When a tadpole undergoes metamorphosis into an adult, the immune system also goes through a drastic transition to maturity. This period of time provides an opening for infection to develop while the defenses of the amphibian aren’t at full capacity. Ultimately, this means that the ability for a species of amphibian to defend against chytrid fungi varies heavily based on the level of innate and acquired defenses mounted, the health of the habitat, the climate, and what part of the life cycle the species in question is in.

 It is abundantly clear that amphibian populations are in great danger as a result of this disease outbreak, so the obvious follow-up question is what can we do about this ongoing threat? While there is no silver bullet for stopping chytridiomycosis outright, there are a number of potentially promising forms of intervention that could help to bring mortality rates down to less extreme levels. In short-term or small scales, the direct treatment of individuals with antifungals is shown to be an effective method of temporarily controlling an outbreak, but more long-term measures are needed to ensure success in restoring populations (Garner et al., 2016). Scheele et al. (2014) provide a framework of three potential classes of action to protect amphibians from fungal infection. The first class is Environmental Manipulation. As mentioned previously, there are a number of environmental factors that influence the chance of successful infection. Reducing the presence chemical pollutants can reduce stress on amphibian populations are lower infection rates. The creation of warm regions in the habitat, such as warm pools of water, areas of high sun exposure to bask in, or the introduction of artificial heat sources can also allow species to initiate behavioural fever, raising their body temperature to levels that are no longer ideal for chytrid fungi to survive. Finally, methods such as bio-augmentation, which involves introducing microbes with the ability to inhibit chytrid fungi to the environment, can potentially provide an ecosystem-wide treatment, so long as proper testing is done to ensure that this will not negatively impact the environment in any way. 

Artificial ponds for the captive breeding of the endangered Pseudophryne corroboree.

(Figure 2 from Scheele et al., 2014)

When manipulation is not a reasonable solution, the Amphibian Introduction class is next in line. This involves the translocation of amphibian populations to refugia: environments that are ideal for the species, but poor for chytrid fungus. This method does require that it is ensured that this translocation will not cause any impacts in the new environment. Alternatively, captive bred amphibians can be added to wild populations in order to increase the buffering capacity of the ecosystem, allowing higher likelihood of survival for a population even after an chytrid epidemic. Finally, failing the previous two classes, the last class is Ex-Situ Conservation, which involves keeping colonies in captivity. Infected individuals are treated with chemicals or heat to kill the fungus, and individuals are bred in order to improve resistance among the population while maintaining genetic diversity (Scheele et al. 2014).

While these treatments are still in development and have not been used in proper field tests yet, they definitely have the potential to rescue amphibian populations. However, the fact remains that many amphibians around the world are critically imperilled, so there is clear need for feasibility research as soon as possible if we want to prevent any more extinctions. The loss of mass amounts of amphibians could lead to huge impacts on many ecosystems around the world, and it is all but guaranteed to happen unless we take action.

Literature Cited:

Ellison AR et al. 2014. Fighting a Losing Battle: Vigorous Immune Response Countered by Pathogen Suppression of Host Defenses in the Chytridiomycosis-Susceptible Frog Atelopus zeteki. G3-Genes Genom Genet 4(7): 1275-1289.

Fisher MC. 2017. Ecology: In peril from a perfect pathogen. Nature 544(7650): 300-301.

Garner TWJ et al. 2016. Mitigating amphibian chytridiomycoses in nature. Philos T Roy Soc B 371(1709).

Rollins-Smith LA et al. 2011. Amphibian Immune Defenses against Chytridiomycosis: Impacts of Changing Environments. Integr Comp Biol 51(4): 552-562.

Scheele BC et al. 2014. Interventions for Reducing Extinction Risk in Chytridiomycosis-Threatened Amphibians. Conserv Biol 28(5): 1195-1205.

Voyles J, et al. 2009. Pathogenesis of Chytridiomycosis, a Cause of Catastrophic Amphibian Declines. Science 326(5952): 582-585.

Wake DB and Vredenburg VT. 2008. Are we in the midst of the sixth mass extinction? A view from the world of amphibians. P Natl Acad Sci USA 105(1): 1466-1473.

Holiday caRd 2018!

I had a busy year, and it completely slipped my mind that I usually do a caRd for the blog! So it's a little late, but hopefully provides a little end of year cheeR ;-)

A short warning: I've stopped trying to make these compatible with RStudio. I know that RStudio is very popular, but I struggle to get its internal plotting device to update iteratively to make an animation (despite trying various things, like while() or if() statements, or Sys.sleep()). If someone has a solution, please share.

To enjoy these plots you should see the animation in real time: e.g. Base R (any operating system) or R run via emacs or vim.

To run, you can access the source file on github

or run this code:

source("https://tinyurl.com/2018rcard")

If you prefer not to run the code, the gif version can be found here!

Into the Eye of the Elephant Storm: Poaching in Africa’s Last Great Elephant Refuge

Guest post by Adam Byers, MEnvSc Candidate at the University of Toronto-Scarborough

It’s hard to put into words the feeling you get gazing up into the gentle, intelligent eyes of a 5-tonne African elephant. But that’s exactly where I found myself six months ago, deep within the borders of Botswana’s Chobe National Park.

Two members of a small bachelor herd in Chobe National Park, Botswana

I was nearing the end of a camping safari across the grasslands of southern Africa, and just when I thought it wasn’t possible to top the incredible wildlife I’d already experienced, Africa proved me wrong in a surreal heart-stopping moment. A towering young bull elephant emerged from the bush and passed by our jeep close enough to touch. It’s the kind of experience you never forget. But it’s an experience that may soon cease to be possible.

The African bush elephant is a threatened species as designated by the IUCN (Blanc, 2008), the global organization that assesses at-risk wildlife. Tracked since 1986, the species is currently listed as “vulnerable”, and recent trends suggest populations are in decline (Chase et al., 2016). Making matters worse, this year elephant conservation was dealt a devastating blow that is already having major consequences: in May, the new president of Botswana revoked the country’s zero-tolerance policy on poaching and stripped the weapons from Parks officers. Mere weeks later, the place of my elephant encounter was transformed into a scene of destruction and violence. By September, surveys carried out by the charity Elephants Without Borders found 87 dead elephants killed for their tusks.

Botswana supports among the densest populations of elephant in Africa (from Chase et al., 2016)

Botswana is home to the world’s largest population of elephants, and has long been esteemed for its tough stance on poaching. A commentary released last year by researchers from the University of Botswana emphasized the nation’s shoot-to-kill order as responsible for reducing illegal hunting (Mogomotsi & Madigele, 2017), which is a leading cause of elephant mortality, particularly for tusked males (CITES, 2017). The belief was widespread, shared with me by guides and park staff from Zimbabwe to South Africa, who lauded Botswana’s approach. So it’s no wonder the policy reversal was met with international outrage, which only intensified with the discovery of dozens of poached elephants in the Chobe park and other protected areas.

The government denied the claims, insisting the numbers were much lower, but in a continent still rife with corruption it is difficult to know who to believe. But whether it’s one elephant or one hundred, the harm is unacceptable. And the fact that it followed so closely after the disarmament of the country’s anti-poaching unit can be no coincidence.

Further investigation, however, shows that despite the likely connection, the government may have done no wrong. The shoot-to-kill policy was never official legislation, and as I was warned during my adventure, there were no real criteria before escalating to violence – simply being in a protected area after dark was sufficient for guards to open fire. This led to several years of clashes between anti-poaching units and citizens of neighbouring nations.

Proportion of illegally killed elephants (PIKE) from 2003 to 2016; the red line represents the level at which half of all deaths are due to illegal hunting or poaching (adapted from CITES, 2017)

Regardless of the controversies and merits of the former anti-poaching strategy, scholars are quick to point out that this sort of harsh response was only a band-aid solution. In an impoverished country ravaged by AIDS, inequality, and lack of clean water, poaching offers a high-risk but extremely tempting escape. Ivory values peaked at over $1,700 per kilo (CAD) in 2015, and with a pair of adult male tusks weighing up to 90kg, a single elephant could represent a lifetime’s salary. The price of ivory has decreased since China’s ban earlier this year, but with a thriving black market trade, and U.S. President Trump reversing a ban on ivory imports, the world is far from a cohesive anti-poaching strategy.

Given the lucrative market, it’s no wonder that a sophisticated system of poachers has descended on the country, especially now that the risk is reduced. But as one ranger in Botswana explained, these poachers are not necessarily bad men. They are sons and brothers. Husbands. Fathers.

If we want to fix the poaching problem, we need to dig deeper for a solution. We need alternative livelihoods for the marginalized men that are turning to poaching in order to provide for their families. Conservation and humanitarian NGOs operating around the world have long tried to implement programs to encourage alternate sources of food and income, but unfortunately few of these programs have had adequate funding or infrastructure to measure the results. To assess whether conservation benefits were being achieved, the IUCN conducted interviews as part of an enlightening assessment of 15 alternative livelihood projects in Central Africa (Wicander & Coad, 2015). In many cases funding was inadequate to meet program targets, and the majority lacked sufficient monitoring to measure progress. These findings were echoed in a systematic review conducted by Dilys Roe and colleagues (2015). The authors found only 21 studies that adequately assessed conservation outcome of alternative livelihood projects, only a third of which were from Africa, and none of those specifically dealt with poaching. Scientists are often quick to raise problems, and usually to suggest solutions, but there is also a need to follow through to determine whether those solutions are working. There is a clear gap that needs to be addressed to determine which interventions are effective at both reducing poaching and meeting socioeconomic goals, and researchers and NGOs must work together to ensure adequate funding is available for such programs.

In the last days of my trip I visited a local primary school where I had the opportunity to meet both students and teachers. Despite its troubles, Botswana is a fast-advancing nation and a leader in education among its peers. Their children today have more choice and freedom than ever before, and it is up to them to set the course for the world’s last great elephant refuge. And I have no doubt they will succeed if we just give them the opportunity, because like their gentle giant neighbours, they are kind and enthusiastic. Thoughtful. Intelligent.
To see it, you just need to look into their eyes.

Photo by Adam Byers

Much of the information in this posting is taken from first-hand experiences and conversations in Botswana and neighbouring nations. For fuller appreciation of the complexities of the issue, I recommend reading the news articles linked above and the referenced studies and documents below. For more on endangered elephant populations or to find out how you can help, visit the IUCN or World Wildlife Fund.


References
Blanc, J. (2008). Loxodonta africana. The IUCN Red List of Threatened Species 2008. International Union for Conservation of Nature and Natural Resources.

Chase, M. J., Schlossberg, S., Griffin, C. R., Bouché, P. J., Djene, S. W., Elkan, P. W., ... & Omondi, P. (2016). Continent-wide survey reveals massive decline in African savannah elephants. PeerJ, 4, e2354.

CITES. (2017). MIKE Report: Levels and Trends of Illegal Killing of Elephants in Africa to 31 December 2016 - Preliminary Findings. Convention on International Trade n Endangered Species of Wild Fauna and Flora.

Mogomotsi, G. E., & Madigele, P. K. (2017). Live by the gun, die by the gun: Botswana’s ‘shoot-to-kill’policy as an anti-poaching strategy. South African Crime Quarterly, 60, 51-59.

Roe, D., Booker, F., Day, M., Zhou, W., Allebone-Webb, S., Hill, N. A., ... & Shepherd, G. (2015). Are alternative livelihood projects effective at reducing local threats to specified elements of biodiversity and/or improving or maintaining the conservation status of those elements? Environmental Evidence, 4(1), 22.

Wicander, S., & Coad, L. (2015). Learning our Lessons: A Review of Alternative Livelihood Projects in Central Africa. International Union for Conservation of Nature and Natural Resources.

Un-BEE-lievable: The Buzz on Native Bee Conservation in Canada

Guest post by University of Toronto-Scarborough MEnvSc Candidate Rachel Siblock

Unless you’ve been living under a rock (much like native mining bees in Canada), you’ve probably seen the numerous campaigns to “Save the Bees”. Bee species across the globe are in decline. There are many factors that contribute to this decline, such as pesticide use, colony collapse, disease, habitat loss, and climate change¹. Many of these factors interact with one another, exacerbating the consequences and impacts. Conservation efforts are being implemented to try to stop the loss of these pollinators, and the valuable services they provide to humans. Canada is no exception. There are local, provincial, and national policies and programs operating and currently being developed in order to reduce the impacts of these threats. In the past few years, programs like The Bee Cause, Bees Matter, Feed the Bees, and others have implemented programs and recommendations in order to increase the bee populations in Canada. Honey Nut Cheerios has even campaigned to get the public engaged and involved in the conservation of bees. These programs, however, all have one common issue: they focus their efforts on Honey Bees. 

An example of a campaign by Honey Nut Cheerios, focusing on honey bees. 

There are no native honey bees in Canada. The most well-known bee in Canada was not even present in the country until it was introduced from Europe in the 1600s². The European Honey Bee was intentionally introduced to Canada for honey production, and since has increased in number dramatically, both in farmed and wild colonies. Honey bees have large colonies, allowing them to be easily managed and farmed. They also pollinate crops and produce honey, which may make them seem more economically valuable than their native, non-honey-producing counterparts. However, there have been unexpected impacts of the introduction of the European Honey Bee on native bee species in Canada.

            There are over 800 native bee species in Canada. While there are many different types of bees in Canada, the best understood group of native bees are bumble bees. Bumble bees have the ability to buzz pollinate, which allows them to obtain pollen from plants with pollen that is difficult to extract. Many of these plants are economically valuable, such as kiwi and blueberry crops. This, along with general pollination, makes managed populations of bumble bees worth several billion dollars annually³. Bumble bees naturally have low genetic diversity and can be subject to inbreeding depression, leading to declining populations and making the some species more vulnerable to extinction⁴. Threats can then interact with these low population levels, and intensify population loss. 

A male Rusty-patched Bumble Bee, one of Canada’s native bee species. It is currently listed as endangered in Canada.

Aside from facing the same threats as honey bees, native bumble bees are also threatened by the very presence of honey bees. Competition for resources with honey bees is a major threat to native bumble bees. A study performed in the United Kingdom found that bumble bees at sites with high honey bee density were significantly smaller in body size when compared to their relatives at sites with low honey bee density⁵. An additional study discovered a reduction of native bumble bee colony success when colonies were experimentally exposed to honey bees⁶. Honey bees generally produce larger colony sizes which can store a larger amount of resources than bumble bees. They also have the ability to communicate with one another about valuable floral resource locations⁷. Honey bees have a larger foraging range than native bumble bees, and have an increased ability to forage on introduced plant species⁷. These adaptations allow honey bees to outcompete native bumble bees, and commandeer sparse resources in the area.

            Threats from honey bees do not just end at competition; pathogens and parasites specifically adapted to honey bees have been shown to have the ability to spread to wild bumble bee populations. Managed honey bees are known to carry higher than natural levels of pathogens⁸, which can be transmitted to wild bumble bee populations when the bees interact. In particular, two pathogens endemic to honey bees, C. bombi and N. bombi, are wreaking havoc on bumble bee populations. While these pathogens do not have lethal effects, their sublethal effects can be devastating to colonies. These pathogens cause reduced pollen loads, a decline in flowers visited per minute, slower growth rates of colonies, decreased queen reproductive rates, shortened life spans and diminished colony growth⁸. With small populations already, entire bumble bee colonies can be wiped out by these pathogens. Honey bee parasites, such as the Small Hive Beetle, have also been shown to be able to spread to bumble bee colonies, where they consume the wax, pollen, and nectar stores of hives⁸. While honey bees have co-evolved with these parasites and pathogens for eons, bumble bees have not had the time to adapt to these threats, making them much more vulnerable to these hazards. 

Small Hive Beetle infestation in a honey bee colony. 

But why do we care about losing native bees? The same concerns about the loss of honey bees applies to native bees. Native bee species pollinate crops and flowers, which we depend on for food. It is estimated that about one in three bites of food we consume can be traced back directly to pollination by bees and other pollinators. However, native bees have been found to be more effective pollinators than honey bees. Some plant species in Canada rely solely on native bees for their pollination. With the loss of native bees, these plants will also become endangered, along with many other food crops requiring pollination. Additionally, there is a severe lack of research into native bees. Research tends to focus on honey bee populations, resulting in much more knowledge of honey bee behaviours, adaptations, actions, and responses to stressors. The truth is, we don’t know much about native bee species in Canada. We have no idea what the consequences of the loss of these species will be. However, this does not excuse us from protecting these bees. If anything, this lack of knowledge should increase our urge to protect them, so we have the opportunity to learn about them in the future.

            The native bee species in Canada share little life history traits with the European Honey Bee⁸, making many conservation efforts that focus on honey bees unsuccessful. Focusing conservation efforts on one species may not address the specific needs of native bees. In addition, by focusing on improving honey bee populations, there will be increased stress on native bees, which will lead to a decline in their populations. If we continue with these conservation strategies, we may threaten native species further.

            An increase in honey bee populations will increase parasite and pathogen levels in native bees, and also increase the competition between honey bees and native bees. So what can you do to focus conservation efforts on native Canadian bees? For starters, avoid the use of pesticides, which will decrease already low populations⁸. Improve your knowledge of bee species, and report invasive or introduced species in areas used by native bee species. Plant a wide variety of native plants with high pollen and nectar concentrations to ensure newly emerging bees have the resources they need to survive. And finally, avoid tilling, mowing, or burning in areas where native bee species, particularly ground dwelling species, are known to live. With increased knowledge of native bee needs, and species specific conservation efforts, it is hoped that native bee species will begin to rebound. Let’s BEE positive!

BEE Informed – To get involved with native bee conservation check out these links:

Native Pollinator Initiative – Wildlife Preservation Canada

Bumble Bee Recovery – Wildlife Preservation Canada

Help Native Bees – Conservation Halton 

Native Bee Information – Canadian Wildlife Federation

BEE-bliography:

    1.     Pettis, J.S., and K.S. Delaplane. 2010. Coordinated responses to honey bee decline in the USA. Adipologie 41:256-263.

    2.     van Engelsdorp, D., and M.D. Meixner. 2010. A historical review of managed honey bee populations in Europe and the United Sates and the factors that may affect them. Journal of Invertebrate Pathology 103:80-95.    

    3.     James, R., and T.L. Pitts-Singer. 2008. Bee Pollination in Agricultural Ecosystems. Oxford University Press, USA.

    4.     Zayed, A., and L. Packer. 2005. Complementary sex determination substantially increases extinction proneness of haplodiploid populations. Proceedings of the National Academy of Sciences of the United States of America 102:10742-10746.

    5.     Goulson, D., and K. Sparrow. 2009. Evidence for competition between honey bees and bumble bees: Effects on bumble bee worker size. Journal of Insect Conservation 13:177-181.

    6.     Thomson, D. 2004. Competitive interactions between the invasive European honey bee and native bumble bees. Ecology 85:458-470.

    7.     Goulson, D. 2003. Effects of introduced bees on native ecosystems. Annual Review of Ecology, Evolution, and Systematics 34:1-26.

    8.     Colla, S.R. 2016. Status, threats and conservation recommendations for wild bumble bees (Bombus spp.) in Ontario, Canada: a review for policymakers and practitioners. Natural Areas Journal 36:412-426.

Image Sources:

  1. https://bringbackthebees.ca

  2. https://inaturalist.com

  3. http://beeaware.org.au/archive-pest/small-hive-beetle/#ad-image-0