Showing posts with label ecosystem services. Show all posts
Showing posts with label ecosystem services. Show all posts

Wednesday, October 31, 2018

Losing the rainforest of the sea: Coral reef decline and loss of future ecosystem benefits and services

*This is a guest post by Karuna Sehgal - student in my 'Causes & Consequences of Biodiversity' course. 

The past three decades of human activity has altered the earth in more ways than one. The Earth is losing species, ecosystems and biodiversity because of warming climates, among other factors. Coral reefs, in particular, are greatly impacted by the rise of global surface temperatures.

Coral Reefs throughout tropical and sub-tropical oceans are under tremendous heat stress resulting in coral bleaching and mortality. Corals are animals that live in a symbiotic relationship with microscopic dinoflagellate algae that inhabit the coral tissues (Baker et al., 2008). Increased water temperatures result in corals expelling dinoflagellates living in their tissues, causing the coral to turn white, ending its symbiotic relationship (Heron et al., 2017). This does not necessarily mean death for the coral; however bleaching still adversely impacts corals by inhibiting growth and reproduction (Heron et al., 2017). This symbiotic relationship provides the coral with about 90% of the energy it needs to thrive, it also enables corals to construct limestone skeletons that form the three-dimensional structure of reefs, which provides habitat for over a million species (Heron et al., 2017. They are referred to as the Rainforests of the Sea because they are the most bio-diverse ecosystem in the ocean, comparable to rainforests on land. Species richness and the diversity found in these systems are phenomenal and breathtaking, and yet they are dying at an alarming rate.

Fig. 1: Examples of a healthy and a bleached coral reef (images modified from Wikipedia pages on coral reefs and reef degradation, respectively)

Coral Reefs provide a lot of ecological and economically important services; they gross an estimated value of over $1 trillion (USD) globally, because of their social, economic and cultural services (Heron et al., 2017). With that being said, reefs only account for less than 0.1% of the ocean floor, but host more than one-quarter of all marine fish species (Heron et al., 2017). Climate change alters the pristine attractiveness of coral reefs to tourists, which directly affects low-income coastal countries and small developing islands within coral reef regions (Hoegh-Guldberg et al., 2007). Developing countries are not equipped to respond to climate change, and many rely on tourism for the majority of their economies (Hoegh-Guldberg et al., 2007). But tourist visits are one form of valuation, coral reefs are also critical for supporting fisheries and protecting shorelines from erosion,  For the loss of reef ecosystem services it is going to cost the US about $500 billion per year by 2100 (Hoegh-Guldberg et al., 2015).

This loss of economic value through bleaching is ultimately caused by our activities. Anthropogenic activity has resulted in rising temperatures and increases in the atmospheric concentration of carbon dioxide; this has been the largest increase in global temperature since the pre-industrial times (Stocker et al., 2013). Widespread mass coral bleaching was first documented in 1983 at the time of an extremely strong El Nino (Cofroth et al., 1989). It is important to note that coral reefs have been around a long time and residing in oceans since at least the Triassic period over 200 million years ago, and are well adapted to specific environmental conditions and human activity has damaged them in a matter of 30 years. Therefore water temperatures of even 1-2oC above the normal temperature would result in severe coral bleaching (Heron et al., 2017). It was estimated that coral reefs would take approximately 15- 25 years to recover from mass mortality, but if the frequency of mass mortality events increases to a point where the return time of mortality event is less than the time it takes to recover, the abundance of corals on reefs will decline (Heron et al., 2017).

Ocean acidification is another factor affecting coral reefs because it hinders the coral's ability to build their limestone skeletons and increases bio-erosion of reefs (Heron et al., 2017). With approximately 25% of the emitted CO2 from anthropogenic sources entering the ocean and producing carbonic acid, which then dissociates to form bicarbonate ions and protons, reducing the availability of carbonate to biological systems (Hoegh-Guldberg et al., 2007). These high CO2 levels and ocean acidification are expected to cause coral reefs to erode. A number of studies have determined that the doubling of pre-industrial atmospheric CO2 to 560 ppm decreases coral calcification and growth by up to 40% through the inhibition of aragonite formation as carbonate-ion concentrations decrease (Hoegh-Guldberg et al., 2007). Studies have concluded that the corals will not thrive again until the atmospheric CO2 has been reduced to 320-350 ppm (Heron et al., 2017).

Building the resilience of these reefs by reducing human impacts is now the main focus of organisations like the World Heritage Committee of UNESCO and the Reef Resilience Network. A World Heritage Committee analysis showed that nearly all of the 29 World Heritage coral reef sites were exposed to levels of heat stress that cause coral bleaching, more than twice per decade during the 1985-2013 period (Heron et al., 2017). Roughly 21 of the World Heritage reef properties have been exposed to repeated heat stress during the past three years (Heron et al., 2017), threatening the long-term persists of these unique and valuable places.

Fig. 2: Satellite image of coral bleaching alerts from  2014–2017 (image from NOAA Coral Reef Watch)
Bleaching and heat stress spread across tropical oceans and intensified during El Niño, and continued from La Niña and beyond (Heron et al., 2017). This period has included the three warmest years on record: 2014, 2015, and 2016 (Heron et al., 2017). Figure 2 shows that more than 70% of the global coral reef locations have experienced bleaching and most of these have experienced it twice or more, since June 2014 (Heron et al., 2017).

What is the future of these reefs? Will the next generation be able to see and explore them as we have or will they have to watch documentaries of what used to be? Coral Reefs are the most biologically diverse and economically important ecosystem on the planet, providing ecosystem services, essential to human societies and they are at danger (Hoegh-Guldberg et al., 2007).


Baker AC, Glynn PW, Riegl B (2008) Climate change and coral reef bleaching: An ecological assessment of long-term impacts, recovery trends and future outlook. Estuarine, Coastal and Shelf Science 80:435-471.
Cofroth MA, Lasker HR, Oliver JK (1989) Coral mortality outside of the eastern Pacific during 1982-83: Relationship to El Niño. In: Global Ecological Consequences of the 1982-83 El Niño-Southern Oscillation. Glynn, PW. (ed.). Elsevier.
Heron et al. 2017. Impacts of Climate Change on World Heritage Coral Reefs : A First Global Scientific Assessment. Paris, UNESCO World Heritage Centre.
Hoegh-Guldberg O, et al. (2015) Reviving the Ocean Economy: the case for action - 2015. WWF International, Gland, Switzerland.Geneva, 60p.
O. Hoegh-Guldberg, P. J. Mumby, A. J. Hooten, R. S. Steneck. (2007). Coral Reefs Under Rapid Climate Change and Ocean Acidificaition. Science, 318, 1-7. Doi: 10.1126/science.1152509
Stocker TF, et al. (2013) Climate Change 2013: The Physical Science Basis. Working Group 1 (WG1) Contribution to the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report (AR5), Cambridge University Press. 


Tuesday, March 27, 2018

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

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

In the world of animal conservation, charismatic wildlife - those loveable, huggable species like giant pandas or koalas - take centre stage. They’re the kinds of animals you see dominating news stories, books, and movies, with less-attractive species often falling by the wayside. The concept of charismatic species is tied closely to animal conservation and protection. And the public’s love and adoration for charismatic creatures plays an essential role in the success of conservation and awareness campaigns. As flagship species they become ambassadors and icons, rallying support and focusing the public’s attention (and money) on an environmental cause or conservation program.
Figure 1 A famous example of a charismatic species used as a flagship species for a conservation group, the World Wildlife Fund (WWF). (Source)

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

A perfect example of a charismatic species as an invasive pest is wild horses, known as brumbies, in Australia. First introduced for farm work in 1788, there are now over 400 000 brumbies throughout the country. As an invasive this species causes erosion and damages vegetation with their hard hooves and overgrazing. They damage and foul waterholes and spread weeds through seeds carried in their dung, manes, and tails. As competitors with native species, they can force wildlife from favoured habitats and dominate food and water sources. There is a significant portion of the public, however, that see the brumby as an iconic Australian species that is  ’a unique equine and epitomizes the spirit of freedom’.
Figure 2 Feral horses threaten fragile ecosystems in Kosciusko National Park. (Source)
To manage the impacts of brumbies in Kosciuszko National Park, a plan was released in 2016 to reduce the number of wild horses by 90% over a 20-year period. The cull was to be carried out using humane control methods including trapping, fertility control and ground shooting rather than aerial shooting and roping. The management plan sparked angry protests and fierce opposition, despite warnings from scientists about the impacts of brumbies in the region. Even though government scientists declared that the horse population in the region severely degrade natural waterways and threaten fragile native alpine wildlife, hundreds of people protested the cull in Sydney and support groups downplayed the adverse effects brumbies have had on the environment. Lisa Caldwell of the Snowy Mountain Horse Riding Association was reported as saying ‘You've got to remember that the national park is 6,900 square kilometres…horses are not going to have a huge impact on those wetlands’ (

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

Now consider how an uncharismatic species is treated in a similar situation. The feral pig, generally perceived as dirty, disease-ridden and hated by farmers, also roams through Kosciuszko National Park and has very similar impacts on the environment. Feral pigs degrade natural areas through rooting up soils, grasslands and forest litter as they feed on native plants. They also spread a number of diseases and predate on a host of native animals including insects, frogs, snakes and small ground-nesting birds. Unlike brumbies however, their numbers are managed within in the park with almost no opposition.
Figure 3 Feral pigs populations are controlled in Australia with minimal public opposition. (Source)
In both cases there are two species found in the same location, negatively impacting the ecosystem in a similar way. For the uncharismatic species, management plans are carried out promptly and effectively. But for the charismatic species, it seems clear that societal bias can lead to strong resistance from the public and as a result, management efforts can be delayed or watered down.

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

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

Monday, November 23, 2015

Conservation’s toughest decision

Guest post by Shelby Hofstetter, currently enrolled in the Professional Masters of Environmental Science program at the University of Toronto-Scarborough

“We should have thrown in the towel years ago!”- the dinner-table conversation takes a drastic turn from gushing over new panda bear cubs at the Toronto Zoo to a more pessimistic view of the state of global panda conservation efforts. The speaker of these words is recalling a program that aired on the CBC when the pandas were first arriving at the Toronto Zoo. In it, host Amanda Lang acknowledged herself as a “panda hater” and expressed her disapproval of the money wasted on continued panda conservation efforts that are based solely on their appearance (link to video below). As someone who queued in line for the chance to take far too many pictures of the adorable bears, I blanch at some of Lang’s comments that pandas are “big and stupid“ and “want to be extinct”. But as a student of conservation, I recognise the underlying truth that we as a society have a bias for spending our conservation dollars on big, fluffy animals, regardless of their likelihood of survival.

(Photo taken by Shelby Hofstetter at the Toronto Zoo)

But what are the alternatives? With the realisation that funds for biodiversity conservation are finite, there has been a long history of debate over the best methods for choosing worthy species. The umbrella species concept seems to be the logical response to this conundrum – the classic 2 for 1 sale where conservation efforts for one species have the added bonus of protecting various other species that share the same ecosystem. This is the reason why some claim that the “big, fluffy” species are often highlighted in conservation projects, because the large, continuous tracts of land that are a necessity for their protection become a safe haven for many more.

The reality of the umbrella species concept may not be as simple however- there is some debate over how well it actually works. In some cases the large habitats required for the umbrella species do not overlap with biodiversity hotspots for other types of organisms like invertebrates, plants, amphibians or reptiles[1]. And unfortunately, even in cases where these pieces of habitat would provide protection for additional species, safeguarding the large amount of land necessary is often unrealistic[2].

Figure 1. Based on phylogenetic diversity, species A would be a higher conservation priority than species B or C as it has fewer close relatives that would be similar genetically[4]

Another response to this conservation riddle is aptly named the “Noah’s Ark Problem”, and is a framework for choosing species for conservation based on cost and likelihood of survival, but also on phylogenetic diversity[3]. This objective focus on phylogenetic diversity, or the amount of genetic history that a species contains, has gained momentum in recent years and is aimed at saving species that encapsulate high amounts of Earth’s evolutionary life history. The hope is that phylogenetic diversity is correlated with genetic diversity in general, which could also give these species a better chance of adapting to a changing planet[4].

Another notion that is becoming more prevalent is the consideration of ecosystem services, or the benefits that humans derive from a species or ecosystem, when planning for conservation projects. This concept is not necessarily centered around a specific species, but is more focused on the ecosystem as a whole. The emphasis on ecosystem services may help increase the perceived relevance of conservation projects, as the benefit to society is being highlighted. The uptake of this idea within global conservation efforts has been slow however, with less than 10% of conservation assessments including ecosystem services as part of their rationale for conservation[5]. There also seems to be a push for determining the corresponding economic and monetary value of the services that ecosystems provide to society. This is a science that, in a world focused on dollars and cents, may become very important to determining which species or areas are worthy of conservation efforts.

The jury is still out on how to best make conservation’s toughest decision-   determining which struggling species on this planet should be the lucky winners of our conservation resources. In the meantime the importance of this issue is becoming very clear, as many suggest that Earth is currently experiencing a sixth mass extinction. Smart and timely decision-making is vital for which species limited conservation efforts should be focused on. I wouldn’t go so far as to call myself a “panda hater”, or suggest that we “throw in the towel” on conservation efforts for big fluffy species that may not be likely to recover, but I do agree that these decisions should go beyond visual appearances.
Additional Links:
link to Amanda Lang video:

1. Marris, E. (2013, December 24). Charismatic mammals can help guide conservation. Nature | News.
2. Fleishman, E., Blair, R., & Murphy, D. (2001). Empirical Validation Of A Method For Umbrella Species Selection. Ecological Applications, 11(5), 1489-1501.
3. Weitzman, M. (1998). The Noah's Ark Problem. Econometrica, 66(6), 1279-1298.
4. Owen, N. (2014). Life on the edge. Significance, 26-29.
5. Egoh, B., Rouget, M., Reyers, B., Knight, A., Cowling, R., Jaarsveld, A., & Welz, A. (2007). Integrating ecosystem services into conservation assessments: A review. Ecological Economics, 63(4), 714-721.