Showing posts with label extinctions. Show all posts
Showing posts with label extinctions. Show all posts

Tuesday, March 24, 2020

The Fight for Bumblebees

*Guest post by Sonya Sharma, a student in Marc's 'Causes and Consequences of Diversity' class.


A rusty patched bumblebee (Getty Images)


Behind the scenes of the food we see stocked in grocery stores are arguably one of the most important organisms in the world, bumblebees (Bombus), which provide pollination in both natural and managed systems. However, human food security may be at risk because of the recent worldwide declines in bumblebee populations.

Land-use change is generally accepted as being the main driver of bumblebee abundance decline. Numerous studies have documented reductions in bumblebee populations more noticeably in areas that have gone through anthropogenic changes, such as agricultural intensification and urbanization. Bumblebee species richness seems to be positively correlated with the availability of grassland resources, such as pollen sources and nesting habitat, which are scarce in agricultural landscapes. Additionally, due to the mechanical disturbances across large areas that are characteristic of agricultural landscapes, they do not typically provide suitable habitat for wild bumblebee populations. Furthermore, bumblebees have a limited flight range, long colony cycle and specific food and nesting requirements that cause them to be especially susceptible to habitat loss.

Another factor that could be leading to the wild bumblebee decline is pathogen spillover from commercialized or domestic bumblebee populations. The commercialization of bumblebees as agricultural pollinators has inadvertently made wild populations more susceptible to a variety of emergent diseases and epidemics. Commercial rearing facilities provide an ideal environment for the development of a high load of pathogens and parasites because of the high density and high rates of transmission in these facilities. Constant pathogen spillover from commercialized bumble bees with high parasite loads could potentially extirpate small wild bumblebee populations. 
 
A bumblebee hive- similar to ones placed in agricultural landscapes (Wikipedia)

A further contributing factor to the decline in bumblebees is the use of pesticides. Specifically, neonicotinoid containing pesticides, which are most widely used globally, have been found to dramatically reduce egg-laying by queen bumblebees. To mitigate neonicotinoids detrimental effects, a new class of pesticides are being adopted worldwide, sulfoximines. However, a recent study suggests that sulfoximines may also diminish queen bumblebees’ reproductive capacity. Exposure to small amounts to a sulfoximine containing pesticide caused colonies to produce 54% fewer male drones and no new queen bees (Meeus et al., 2011). Therefore, pesticide use is very likely a contributing factor to the widespread bumblebee decline.

All factors considered; we can conclude that bumble bee populations are in serious risk of losing diversity and possibly going extinct. However, when it was proposed in June 2018 to include four species of bumblebee in the Californian Endangered Species Act, the state was sued by the Californian Farm Bureau Federation and six other agricultural associations. These groups argue that bees cannot be protected under this law because it defines candidate species as “bird, mammal, fish, amphibian, reptile or plant” and does not list any insects.

This conflict in government policy is not unique to California however, and is an example of the longstanding tension between conservation biologists and the agricultural industry about the protection of pollinators. If bumblebees were listed on the Californian Endangered Species Act it would restrict grazing, pesticides and the use of commercial bumblebees. It could also limit where bumblebee hives could be placed. Farmers and ranchers claim that listing bumble bees would harm agricultural production dramatically.

Other environmentalists suggest that attempts to conserve bumblebees should focus more on wildlife-friendly approaches such as increasing agricultural land set-asides, hedgerows and employing integrated pest management. Whatever the strategy taken through policy to protect bumblebees, it should aim to increase the abundance of grassland resources, reduce pathogen spillover from commercialized populations and reduce the use of harmful pesticides. How to create a policy that will appease both the agricultural industry and conservation biologists is still up for debate. However, all can agree that bumblebees are an indispensable member of both managed and natural ecosystems.

Works Cited:
Grixti, J. C., Wong, L. T., Cameron, S. A., & Favret, C. (2009). Decline of bumble bees (Bombus) in the North American Midwest. Biological Conservation, 142(1), 75–84.

Meeus, I., Brown, M. J. F., Graaf, D. C. D., & Smagghe, G. (2011). Effects of Invasive Parasites on Bumble Bee Declines. Conservation Biology, 25(4), 662–671.


Further reading:
Sulfoximine pesticide effects on bumble bees: https://www.the-scientist.com/news-opinion/New-Pesticide-Affects-Bumblebee-Reproduction-64647

California Cotton Growers petition: https://www.cottonfarming.com/special-report/seven-ag-groups-file-lawsuit-regarding-bumblebee-species/

Conservation Groups Join California in Legal Dispute Over Protecting Bumblebees: https://www.kqed.org/science/1956515/conservation-groups-join-california-in-legal-dispute-over-protecting-bumblebees

If Bumble Bees Become Endangered In California, Farmers Say It Sets A ‘Dangerous Precedent: http://www.capradio.org/articles/2020/02/05/if-bumble-bees-become-endangered-in-california-farmers-say-it-sets-a-dangerous-precedent/


Monday, March 9, 2020

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., DahdouhGuebas, 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



Monday, April 3, 2017

Biodiversity conservation in a human world: do successes involve losses?

It's become commonplace to state that the world is in the midst of a mass extinction event. And there is no doubt about the cause. Unlike previous mass extinction events, like the cretaceous extinction event that saw most dinosaurs disappear, the current extinction event is not caused by a geological or astrological event. Rather, the current extinction event is caused by a single species, humans. Through habitat destruction, wildlife harvesting, pollution, and the introduction of pest species to other regions, the current extinction rate is 100 to 1000 times higher than it should normally be. We often think of human legacy in terms of art or architecture, but a permanent scar in the biological record of the Earth is our greatest legacy.

Of course many people and some governments are very concerned about our impact, and have committed to try to conserve elements of the remaining natural world. How best to do this is largely influenced by conservation biology, a field of research and applied management that includes biology, economics, and sociology, amongst others. There are many debates within conservation biology, and a big one is about how much to involve people, and their activities, in conservation areas versus attempting to completely exclude people from protected areas.

Two conservation conversations have explored this dichotomy in meaningful ways. First is a recent paper by Elena Bennett (Bennett 2017), who argues that strategies for environment and conservation protection needs to take a human-first approach and focus on human well-being. The second is a talk I saw from Daniel Janzen the other day. Janzen is a world-renowned ecologist and has dedicated his life to conservation in Costa Rica for the past 30 years. This debate was central to his talk about the conservation successes at the Area de Conservacion Guanacaste (ACG), where Janzen developed and implemented a conservation philosophy that included local people in the managing and research in the conservation area. Before Janzen, the Park relied on the traditional approach of excluding people to protect nature and it was failing. Janzen’s approach has been immensely successful, and the Park is now considered a conservation success story.

People can be convinced to appreciate biodiversity around
-if it provides a benefit. (photo by M. Cadotte)
Including people in nature conservation is bound to have successes. People feel more familiar and involved with nature protection, which gives them a sense of ownership. If people understand the benefits of nature, economic and otherwise, then they will be invested in its protection. It all seems so logical, but as I listened to Janzen’s talk (and read Bennett’s paper), I kept thinking: “would there be any losers under a human-first approach to conservation”. I think the answer is yes, and the reason is that we are prone to use a shifting baseline to evaluate success. Let me explain what I mean.

The human-nature story is one that is about a continual 30,000 year retreat. All of our successes -our population growth, our art, our medicine, have all come at the expense of nature. Anywhere on Earth where there are humans, there are losses. Habitat alteration and destruction, and species extinctions are the defining feature of our presence. This legacy has permanently altered the biology of our planet.

Why is this important? Because we really don’t care. We don’t miss wholly mammoths in northern Europe. We don’t miss giant sloths in California. We don’t miss black bears in downtown Toronto. We don’t miss lions in Cape Town. The definition and acceptance of nature  for most people is not influenced by what is not there, but rather the critters we are familiar with and are willing to accept. Big mammals simply have no place in human dominated landscapes and we don’t bemoan their absences.

Can human-first conservation protect jaguars?
(Photo from wikipedia)

Human-first conservation strategies work simply because we accept a less valuable system as acceptable and perhaps normal because of our shifting baselines. Would a human-first conservation strategy work in Costa Rica’s ACG if there was a huge jaguar population that was attacking livestock? Not likely.

The United States government spends billions on national parks to conserve nature (among other things), but if it was up to ranchers living near Yellowstone, for example, all the top predators will be exterminated. Hunters and ranchers in Germany are similarly up in arms (literally) over the re-appearance of wolves and lynx in restored forests within Germany’s borders. Some there consider the extermination of large predators a commendable feat of an advanced society.

The point is that we like the nature we know, and the nature that is not likely to kill us. People are most often invested, familiar, and willing to conserve nature around them, which already works for them.

Costa Rica’s ACG human-first conservation works in certain contexts. It gets people involved, it protects certain facets of nature, and it has a high likelihood of long-term success. If this is the model for a successful conservation philosophy, then we must accept that not all of nature can be protected. In all likelihood, many large mammals will go extinct in my childrens’ lifetime, regardless of how well we do conservation. So perhaps, moving forward with the human-first strategy is the best option, but a part of me hopes that there is a place for real nature in our world. The rest of me knows that there isn’t.


Bennett, E. M. 2017. Changing the agriculture and environment conversation. Nature Ecology & Evolution 1:0018.

Monday, February 27, 2017

Archiving the genomes of all species

There is so much bad news about global biodiversity, that it is nice to hear about new undertakings and approaches. One of these is the 'Earth BioGenome Project' which proposes to sequence the genomes of the entirety of life on earth. Given that sequencing services have never been more affordable and more available to scientists, without question, though ambitious this is a feasible undertaking. Still, with perhaps 9 million eukaryotes on the planet, a rough prediction suggests it could take 10 years and several billion dollars to achieve.

The cost suggests a certain agony of choice - what is the best use of that amount of money (in the dream world where money can be freely moved between projects)? Direct application to conservation and management activities, or a catalog of diversity which may be the only way to save some of these species? 
Leonard Eisenberg's tree of life (https://www.evogeneao.com).

Saturday, February 13, 2016

The vanishing pangolin: How do you change the value of an endangered species?

Extinction is forever. Extinction reduces the biological heritage of the Earth and is something that we cannot undo.

While living in China, and traveling around Asia, I have said something to my children I have never said before: “I want you to take a really good look, these animals will go extinct in your lifetime”.  I said this as we were watching 8 of the 60 remaining Hong Kong pink dolphins.

Hong Kong pink dolphin (photo by Shirley Lo-Cadotte)

Species become rare and endangered for many reasons, like habitat destruction, pollution, human facilitated spread of problematic species (rats for example), and direct harvesting. While all of these factors are subject to laws and regulations that attempt to control them, it is the last one, harvesting, that relies most on altering peoples' wants and desires. I don’t know why, but to me it is also the saddest cause, the idea that a species dies out because we desire it and kill it or chop it down, just doesn’t seem right.  

Walking through the market alley near my apartment in Guangzhou, China, I saw something that both intrigued and horrified me: a dead and quartered pangolin. You may not be familiar with pangolins –also called scaly anteaters; they are mammals about the size of a large cat or medium-small dog (like a cocker spaniel), with a very long and thick prehensile tail that they use in trees. Their most unique feature is that they are covered in large flat scales that are made of keratin –the same as your fingernails. 

A Chinese pangolin, Manis pentadactyla (https://commons.wikimedia.org/wiki/File:Pangolin%27s_tail.jpgsted to Flickr by verdammelt cc-by-sa-2.0) 
Pangolins are critically endangered. They also have the distinction of being one of the most trafficked animals in the world. In China and Vietnam there is high demand for pangolins because they are considered a delicacy and more importantly their scales are used in traditional medicine. These scales are believed to provide a cure for a number of diseases, including cancer. The incidence of cancers in China is skyrocketing, which is not surprising given the level of pollution, and couple this with increasing affluence, the desire and ability to pay for pangolin parts has never been greater.

Obviously pangolin scales do not cure cancer. You might as well save your money and suck on your fingernails instead, but evidence and logic are not likely to sway mortal fear. There are groups in Asia dedicated to protecting endangered animals and educate citizens about wildlife. Such organizations have an opportunity to capitalize on recent attitude shifts in China and elsewhere, where animal wellbeing is increasingly seen as important. In China, pet ownership has increased dramatically over the past decade and pets are now seen as companions –which I suspect was partially a result of the one-child policy. But the demand for pangolins still exists. When we visited the Angkor Conservation Centre in Cambodia, which works tirelessly to rehabilitate animals and educate people, they were recovering from the theft of one of their pangolins from an enclosure, which they knew was transported to China.

The Chinese authorities are coming down hard on the illegal pangolin trade. They now routinely arrest individuals selling pangolins and seize large shipments. While such seizures and arrests show that the Chinese government is taking pangolin protection seriously, there is only so much they can do while demand is high.

Police confiscating a large illegal pangolin shipment bound for China (photo originally from news.163.com) 

My Mother-in-law, who is from southern China, said it best when I told her about the dead pangolin in the alley: “people just need to be educated”. That is really where the answer lies. Laws can only change peoples’ behaviour so much; education campaigns are desperately needed. Currently, there is an internationally funded billboard campaign in China to stop people from buying elephant ivory. Ivory demand is high in China. Despite the importance of reducing ivory purchases, I would argue that this type of education campaign needs to focus a little closer to home, and Pangolin conservation efforts are in desperate need of help. 

When we were visiting the conservation centre in Cambodia, I told my children that the Pangolin would go extinct in their lifetime. I really hope that I am wrong.




Tuesday, November 10, 2015

Culling Koalas for Conservation

Guest post by Stefanie Thibert, who is currently enrolled in the Professional Masters of Environmental Science program at the University of Toronto-Scarborough


Euthanizing diseased koalas may be the most effective management strategy to save koalas from extinction in Queensland. A recent study published in the Journal of Wildlife Disease suggests that if 10% of terminally diseased and sterile koalas were culled while other infected koalas were treated with antibiotics, chlamydial infections could be completely eliminated and population sizes could increase within four years. 
The beloved koala relaxing in a eucalyptus tree
(Source:
http://www.onekind.org/be_inspired/animals_a_z/koala/) 

Although koalas are under pressure from habitat degradation, dog attacks and road accidents, disease burden is the largest threat to its population sizes. It is estimated that 50% of the current koala population in South-East Queensland is infected with the Chlamydia spp. The sexually transmitted disease causes lesions in the genitals and eyes, leading to blindness, infertility, and ultimately death. Rhodes et al. (2011) suggest that reversing the observed population decline in Queensland koalas would require either entirely eliminating deaths from cars and dogs, complete reforestation, or reducing deaths caused by Chlamydia by 60%. It is clear that the best conservation tool is to reduce the prevalence of chlamydial infection.

In the study, Wilson et al. (2015) examined the potential impact of euthanizing koalas infected with Chlamydia. As shown in Figure 1, computer simulation models were used to project koala population sizes based on four separate intervention programs: “no intervention”, “cull only”, “treat only”, and “cull or treat”. In the “cull or treat” program, sterile and terminal koalas were euthanized, while infected kolas that were not sterile or terminal were treated with antibiotics. It was concluded that the “cull or treat” is the most successful intervention program for increasing long-term population growth and eliminating chlamydial infections. 
The projected numbers of koalas in the Queensland population under different intervention programs.(From Wilson et al. 2015)
Without intervention, it is estimated that merely 185 koalas will persist in 2030. Under both the “cull only” and “treat only” intervention, it would take seven years before there would be greater koalas numbers than there would be without intervention. Under the “cull or treat” program, the population size was projected to overtake the no-intervention population after four short years. The population size in 2030 is also greatest under the “cull or treat” intervention. The increase in koala numbers in the “cull or treat” strategy is due to the considerable decrease in the prevalence of Chlamydia.
As expected, the proposal received considerable attention and was scrutinized by the public. Some argue that it is inhumane, while others suggest alternative management strategies. However, when it comes down to it, the science is clear. Euthanizing can be done in a humane way, and it is the most effective method for conservation of the species. The only real alternative to culling is treatment with antibiotics, which is costly, requires an immense amount of monitoring, and has been shown to take much longer to eliminate the disease and increase population sizes.
The question we must ask ourselves is: we cull other species, so why not koalas? For instance, in the United States, the culling of four million cattle successfully prevented bovine tuberculosis from spreading to humans. Even when based on sound scientific research, culling has always been dismissed as a management option for the iconic Australian marsupial. In 1997, culling was suggested as a method to protect the overabundant koala population on Kangaroo Island, but sterilization and relocation was used instead. It is amazing that a program that was significantly more expensive and less effective was chosen because the public could never think of killing the adorable and innocent koala.
Managing koala populations is clearly a case in which science intersects with emotion. However, it is essential that we put our emotions aside, and make a decision that is based on scientific evidence. Let us remember that the study only suggests culling or treating 10% of the population each year, which is equivalent to approximately 140 koalas. It is also important to improve the communication of science to the public. It needs to be made abundantly clear that without culling, the koala populations will continue to decrease.


To read the full article visit: http://www.bioone.org/doi/full/10.7589/2014-12-278 

References:

Oliver, M. (2015, October, 20). Proposal to euthanise koalas with chlamydia divides experts. The Guardian. Retrieved from: http://www.theguardian.com/world/2015/oct/20/proposal-to-euthanise-koalas-with-chlamydia-divides-experts.

Olmstead, A.L., & Rhode, P.W. (2004). An impossible undertaking: The eradication of bovine tuberculosis in the United States. Journal of Economic History, 64, 734-772.

Rhodes, J.R., Ng, C.F., de Villiers, D.L., Preece, H.J., McAlpine, C.A., & Possingham, H.P. (2011). Using integrated population modeling to quantify the implications of multiple threatening processes for a rapidly declining population. Biological Conservation, 144, 1081–1088.

Wilson, D., Craig, A., Hanger, J., & Timms, P. (2015). The paradox of euthanizing koalas to save populations from elimination. Journal of Wildlife Diseases, 51, 833-842.