27 Apr Ecological Distancing? Safeguarding Biodiversity and Human Health
Ecological Distancing? Safeguarding Biodiversity and Human Health
From the Making Biodiversity Count Series
Canada is increasing protected areas but how do we pay for them?
From the Making Biodiversity Count Series
Biodiversity Action Agenda Item 3.6
Require connectivity mapping and hotspot identification be integrated into Official Community Plans and Land and Resource Management Plans.
COVID-19, biodiversity and human health
Remarkably, the timing of this blog post exploring biodiversity hotspots and habitat connectivity coincides with a global pandemic, when most of Earth’s human population is obsessed with avoiding COVID-19. Physical connectivity in this context is reckless and dangerous.
Although there are some competing theories, the virus is believed to have found its way to humans from a species of wildlife. Such ‘viral spillover’ events have always occurred but are very much on the rise. Nearly all recent pandemics and more than 70% of emerging infectious diseases stem from or involve wildlife (Allen et al., 2017; Salerno et al., 2017). The way to avoid viral spillover, experts say, is to reduce physical connectivity between humans and other species carrying viruses that can spill over — typically, but not always — bats, rodents, migratory birds, and non-human primates. This has important implications for how we approach planning for biodiversity conservation along with ecosystem and habitat connectivity.
Before COVID-19, I would have advocated for improving connectivity of natural habitats via the urban and suburban ‘matrix’ of modified landscapes — the remnant patches, backyards, green roofs, balcony gardens, and other spaces that can provide a link to natural areas. This would help make the landscape more accessible for species that need to move among habitats. Before COVID-19, I would have emphasized the importance of spending time in nature to view wildlife and for general human health and well-being. This helps deepen the attachments that tend to lead to better care for ecosystems and wild species.
Can anyone imagine a world where instead of protecting the green spaces in and around urban areas, and visiting natural settings for recreation, we actively reduce these spaces and behaviours to protect human health? I suggest that we are laying the foundation for precisely this type of outcome.
Biodiversity and pandemic hotspots
All species carry viruses and other pathogens. Within a healthy animal population, these pathogens may exist without causing any significant harm. Or, they may cause disease but at levels that are so low that the impact on the population as a whole is negligible. Disease is often held in check by ecological processes. When populations become unusually high, viruses more easily spread and cause die-offs that bring them into some level of harmony with the extent and quality of their habitats. Natural predators cull the weak, and competitors lessen the abundance and densities of species that host pandemic-generating viruses. Looking at hantavirus, researchers (Keesing et al., 2010) found high levels of small mammal biodiversity reduced deer mouse encounters and the prevalence of infection, for example.
It is well understood that we humans have been part of these landscape-level processes for thousands of years, and we are generally well tolerated by wildlife when our impacts are low. But in the Anthropocene, our impacts are rarely low. Natural areas with rich biodiversity and critical habitats attract human visitors and common forms of encroachment that lead to ecosystem and habitat degradation and destruction. These include resource extraction, real estate development, tourism, everyday recreation, and so on. Abruptly or incrementally, we alter ecological relationships and squeeze wildlife into smaller and smaller spaces. We unwittingly create the conditions for disease emergence and spread in our natural landscapes, not unlike farming practices that crowd livestock. We fragment wildlife habitats with roads and other infrastructure, disconnecting them from food and water sources, places to shelter, and peace and quiet. As these become scarce, wildlife are increasingly stressed (Ziolo, 2020). Not unlike humans experiencing stress, some animals succumb to illnesses that they might otherwise ward off or overcome.
As we create more and more interfaces between built environments and natural ones, we generate opportunities for human-wildlife interactions. David Quammen, author of Spillover: Animal Infections and the Next Human Pandemic, described how human disturbances ‘shake loose’ viruses from their natural hosts to replicate in a new environment. The virus may be amplified in an intermediate host or vector, or may spillover to us. Since we are social and highly mobile, we are the perfect hosts.
As recent events have clearly shown, the globe is very well-connected for disease transmission. So too is it connected for biodiversity and habitat loss. In parts of the world where people rely on wildlife or ‘bushmeat’ for food and are more directly susceptible to viral spillover, our hunger for cell phones and exotic foods drives many forms of impactful encroachment, such as mining and deforestation. Climate change, a noteworthy global connection, contributes to spillover conditions by shifting species ranges, disrupting cycles and seasons, disaggregating ecosystems, and altering vector behaviour, for example.
Humans are not just victims of viral spillover and pandemics;
we are often the cause of them, in countless ways.
Areas frequently associated with the emergence of infectious disease (sometimes called ‘pandemic hotspots’) align with biodiversity hotspots — including those in the northern hemisphere (Allen et al., 2017; Salerno et al., 2017; Wilkinson et al., 2018; Ziolo, 2020). This is partly due to the larger number of potential hosts in areas of high biodiversity, (Wilkinson et al., 2018), and the ‘depth of the pathogen pool’ from which novel pathogens might emerge (Allen et al., 2017). A closer look shows us that emergence of novel pathogens is often associated with recent land use changes that fragment and create interfaces with biodiverse forests (Allen et al., 2017; Olivero et al., 2017; Rulli et al., 2017; Walsh et al., 2019). Emergence events are frequently near dense human settlements and areas that are already highly disturbed (Pandit et al., 2018).
How do we safeguard biodiversity and human health?
COVID-19 reminds us that connections matter. It is an indicator of humanity’s troubled connections with species and their habitats. We now have an opportunity to change these relationships. This begins with recognizing that human health, wildlife health, environmental health, and planetary health are woven together. We can also take tangible steps to avert another spillover event:
Conserve areas of rich biodiversity with minimal edges: Although the relationships among biodiversity and viral spillover are very complex (I have barely scratched the surface here) biodiversity is believed to be generally protective against viral spillover (Keesing et al., 2010; Walsh et al., 2019). Scientists have demonstrated with models that maintaining core, structurally and functionally intact habitats, and not fragmenting them, would reduce the risk of pathogen spillover (Faust et al., 2018; Wilkinson et al., 2018).
Conserve connectivity among biodiverse areas: Since many of our core habitats are now too small or degraded to be functionally sound, it is essential that we consider and possibly redesign the broader landscape. If we maintain and enhance corridors, stepping stones, and other connections among habitat patches, we will not only protect humans and other species from viral spillover, but we will maintain other ecosystem services as well, and help all species adapt to a changing climate. However, in considering human-wildlife interfaces, and the notions of connecting natural ecosystems to urban areas and promoting wildlife viewing, we need surveillance systems and new thinking that will safeguard human health, wildlife health, biodiversity and habitats – at the edges and beyond.
Integrate ecological and health knowledges, practices, and learning among relevant disciplines, sectors, and communities: This includes Indigenous and local knowledges and practices. There are a number of established frameworks that are designed specifically for this integrative work. See: Community of Practice in Ecosystem Approaches to Health (CoPEH), EcoHealth, EcoHealth journal, Canadian Wildlife Health Cooperative, One Health, One Health Initiative, Planetary Health Alliance, Planetary Health – Lancet journal, and my organization, the ECHO Network.
Allen, T., Murray, K. A., Zambrana-Torrelio, C., Morse, S. S., Rondinini, C., Marco, M. D., Breit, N., Olival, K. J., & Daszak, P. (2017). Global hotspots and correlates of emerging zoonotic diseases. Nature Communications, 8(1), 1–10. https://doi.org/10.1038/s41467-017-00923-8
Emergence Magazine. (2020, March 30). Shaking the Viral Tree: An Interview with David Quammen. Retrieved April 17, 2020, from https://emergencemagazine.org/story/shaking-the-viral-tree/
Faust, C. L., McCallum, H. I., Bloomfield, L. S. P., Gottdenker, N. L., Gillespie, T. R., Torney, C. J., Dobson, A. P., & Plowright, R. K. (2018). Pathogen spillover during land conversion. Ecology Letters, 21(4), 471–483. https://doi.org/10.1111/ele.12904
Keesing, F., Belden, L. K., Daszak, P., Dobson, A., Harvell, C. D., Holt, R. D., Hudson, P., Jolles, A., Jones, K. E., Mitchell, C. E., Myers, S. S., Bogich, T., & Ostfeld, R. S. (2010). Impacts of biodiversity on the emergence and transmission of infectious diseases. Nature, 468, 647–652. https://doi.org/doi:10.1038/nature09575
Olivero, J., Fa, J. E., Real, R., Márquez, A. L., Farfán, M. A., Vargas, J. M., Gaveau, D., Salim, M. A., Park, D., Suter, J., King, S., Leendertz, S. A., Sheil, D., & Nasi, R. (2017). Recent loss of closed forests is associated with Ebola virus disease outbreaks. Scientific Reports, 7(1), 14291. https://doi.org/10.1038/s41598-017-14727-9
Pandit, P. S., Doyle, M. M., Smart, K. M., Young, C. C. W., Drape, G. W., & Johnson, C. K. (2018). Predicting wildlife reservoirs and global vulnerability to zoonotic Flaviviruses. Nature Communications, 9(1), 1–10. https://doi.org/10.1038/s41467-018-07896-2
Rulli, M. C., Santini, M., Hayman, D. T. S., & D’Odorico, P. (2017). The nexus between forest fragmentation in Africa and Ebola virus disease outbreaks. Scientific Reports, 7(1), 1–8. https://doi.org/10.1038/srep41613
Salerno, J., Ross, N., Ghai, R., Mahero, M., Travis, D. A., Gillespie, T. R., & Hartter, J. (2017). Human-Wildlife Interactions Predict Febrile Illness in Park Landscapes of Western Uganda. EcoHealth, 14(4), 675–690. https://doi.org/10.1007/s10393-017-1286-1
Walsh, M. G., Mor, S. M., Maity, H., & Hossain, S. (2019). Forest loss shapes the landscape suitability of Kyasanur Forest disease in the biodiversity hotspots of the Western Ghats, India. International Journal of Epidemiology, 48(6), 1804–1814. https://doi.org/10.1093/ije/dyz232
Wilkinson, D. A., Marshall, J. C., French, N. P., & Hayman, D. T. S. (2018). Habitat fragmentation, biodiversity loss and the risk of novel infectious disease emergence. Journal of the Royal Society, Interface, 15(149). https://doi.org/10.1098/rsif.2018.0403
Ziolo, Mira. (2020, April 15). Karma… Mother Nature Fights Back with a virus. CoPEH Canada EcoHealth in Action Webalogue, Learning for Planetary Health: Early Lessons from a Pandemic. https://viuvideos.viu.ca/media/Learning+for+Planetary+HealthA+Early+Lessons+from+a+Pandemic/0_zkd5q92r
About Making Biodiversity Count Series
In February 2019, the Biodiversity Action Agenda, authored by Women for Nature was published. It asks all Canadians to take immediate action on biodiversity loss as there is no recovery from extinction. As a 24-point action agenda, it offers a combination of actions, including low-hanging fruit as well as long-term systemic changes. Follow our blog for bi-weekly posts exploring each action.
As Canadians, we could become stewards of some of the planet’s greatest reservoirs of life and its natural systems upon which we all depend.
Most species at risk of extinction are in the tropics. That's why we should act globally as well as locally when it comes to tackling biodiversity loss.
Canada faces many challenges with conserving our biodiversity, but there are many evidence-based programs in place to help.