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Is Forest Fragmentation The “New” Deforestation?

Posted on by Ariadne Wilkinson
Global Forest Fragmentation is destroying our most important ecosystems.
Global Forest Fragmentation is destroying our most important ecosystems.

 

It’s a well-known fact that deforestation is happening at extreme rates! Just look at the Amazon rainforest, where 20 football pitches worth of trees are removed every minute (Carrington, 2013). These global environmental changes are associated with our topic for today: fragmentation!

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WHAT IS FRAGMENTATION?

Forest fragmentation occurs when the total cover of a native forest is reduced. It is associated with anthropogenic deforestation, and leads to patchy forests and overall forest loss (Murcia, 1995) (Kupfer et al, 2006).

The isolated patches of forested habitats (remnants) in between the cleared forest cover follow the theory of ‘Island Biogeography’. Principles of Island Biogeography link forest fragmentation with biodiversity loss (Kupfer et al, 2006).

This is a good representation of forest fragmentation by Bacles & Jump (2011). The remnants have a drastically different ecosystem than their surroundings, just like an Island’s ecosystem is isolated from the outside world.
This is a good representation of forest fragmentation by Bacles & Jump (2011). The remnants have a drastically different ecosystem than their surroundings, just like an Island’s ecosystem is isolated from the outside world.

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FRAGMENTATION EFFECTS ON ECOSYSTEMS

 

– Microclimate Change (Saunders et al, 1991)

The microclimate within and surrounding the remnant forest is altered in the following ways:

More solar radiation. This restricts shade-tolerant species and encourages the spread of new species of plants (ex. vines, secondary vegetation) and animals to occupy the forest clearings and edges.

The accompanied temperature rise alters soil moisture and nutrient availability, modifying the local vegetation. It also disturbs species interactions and animal foraging behaviours (ex. Carnaby’s cockatoos).

Image by Georgina Steytler: A Carnaby’s Black-Cockatoo (Calyptorbynchus funereus latirostrus). Higher temperatures in fragmented cockatoo habitats reduced their foraging time available, which led to their local extinction in areas of Western Australia (Saunders et al, 1991)
Image by Georgina Steytler: A Carnaby’s Black-Cockatoo (Calyptorbynchus funereus latirostrus). Higher temperatures in fragmented cockatoo habitats reduced their foraging time available, which led to their local extinction in areas of Western Australia (Saunders et al, 1991).

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Stronger winds. Reducing the denseness of the forest leaves it more exposed to penetrating winds. That, amongst other things, changes vegetation structures and food availability for the forest communities.

Increased water flux. Fragmented forests alter the landscape through heavy water flows that erode the topsoil and transport more particulate matter across the forest cover.

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– Isolation (Saunders et al, 1991)

Remnant forest habitats are usually left crowded, with more species than they can actually support. Therefore, over time species will inevitably be lost due to the lack of resources and space available.

Species survival will generally depend on how well they can adapt to new conditions or migrate to new areas. The most rapid extinctions will occur for species with small populations, or ones that are heavily dependent on native vegetation or large territories.

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– Greenhouse Effect

Tropical rainforests store large amounts of carbon. Destroying them releases this stored carbon into the atmosphere and largely contributes to global warming (Laurance et al, 2002).

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MADAGASCAR

Fragmentation is a serious issue for this biodiversity hotspot, and its all due to human activities.

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Fragmentation is a major concern for Madagascar: The original extent of the eastern rainforest was around 3 times larger than what it currently is!

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Prior to human colonisation the forest on the eastern highland spine of Madagascar was 11.2 million ha, but by 1985 it only covered 3.8 million ha (Green & Sussman, 1990). (These satellite images can be found in Conservation Corridor).

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Its size is diminishing due to fires, illegal logging and agricultural deforestation (Ganzhorn et al, 2001).

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The forest on the Eastern Highland spine of the island is shrinking very fast. Forest can only survive within the gullies, where the fires can’t reach it. Image by: Josia Razafindramanana.
The forest on the Eastern Highland spine of the island is shrinking very fast. Forest can only survive within the gullies, where the fires can’t reach it. Image by: Josia Razafindramanana.

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Many larger species have been lost, and the remainder are unlikely to maintain viable populations beyond 2040. Populations of lemurs with fewer than 40 adults cannot survive. Worryingly, none of the remnant patches on the eastern Madagascar forest are large enough to maintain even such populations (Ganzhorn et al, 2001).

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Lemurs are holding on to the trees for dear life. The high rate of fragmentation is a major concern for these primates, as well as for all of Madagascar’s endemic forest ecosystems. Image by Frank Vassen
Lemurs are holding on to the trees for dear life. The high rate of fragmentation is a major concern for these primates, as well as for all of Madagascar’s endemic forest ecosystems. Image by Frank Vassen.

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THE ONLY SAVING GRACE: CONNECTIVITY

Corridors to connect remnants have proven useful when striving to enhance biodiversity.

They can aid the re-colonisation and immigration of species, provide refuge, and help with further species interactions (Saunders et al, 1991) (Laurance et al, 2002).

The size and shape of the remnants can also affect its vulnerability to external factors:

The best conditions for the conservation management of the ecosystems within remnant patches or forest (here they are termed ‘reserves’ from the “Island-like reserves” biogeography theory) can be seen in this image. The theory of forest connectivity is linked to this.

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Word Count: 499

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FOR MORE INFORMATION ON:

Fragmentation effects on ecosystems you can watch: https://www.youtube.com/watch?v=lzf-uX6kGkk

How Madagascar is managing its lemur populations you can watch: https://www.youtube.com/watch?v=ZhOyD79ymJA

 

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REFERENCES:          

          Carrington, D. (2013). Amazon deforestation increased by one-third in past year. [online] the Guardian. Available at: https://www.theguardian.com/environment/2013/nov/15/amazon-deforestation-increased-one-third [Accessed 18 Mar. 2017].

          Ganzhorn, J., Lowry, P., Schatz, G. and Sommer, S. (2001). The biodiversity of Madagascar: one of the world’s hottest hotspots on its way out. Oryx, 35(04), p.346.

          Green, G. and Sussman, R. (1990). Deforestation History of the Eastern Rain Forests of Madagascar from Satellite Images. Science, 248(4952), pp.212-215.

          Kupfer, J., Malanson, G. and Franklin, S. (2006). Not seeing the ocean for the islands: the mediating influence of matrix-based processes on forest fragmentation effects. Global Ecology and Biogeography, 15(1), pp.8-20.

          Laurance, W., Lovejoy, T., Vasconcelos, H., Bruna, E., Didham, R., Stouffer, P., Gascon, C., Bierregaard, R., Laurance, S. and Sampaio, E. (2002). Ecosystem Decay of Amazonian Forest Fragments: a 22-Year Investigation. Conservation Biology, 16(3), pp.605-618.

          Murcia, C. (1995). Edge effects in fragmented forests: implications for conservation. Trends in Ecology & Evolution, 10(2), pp.58-62.

          SAUNDERS, D., HOBBS, R. and MARGULES, C. (1991). Biological Consequences of Ecosystem Fragmentation: A Review. Conservation Biology, 5(1), pp.18-32.

 

 



Eutrophication: A powerful poison to aquatic life

Posted on by Xi Lan

 

3Such tragic pictures were taken in China telling stories of the low-income people who live on fisheries lost their fishes due to the algae bloom. However, this problem does not only present in China: according to reports, during 1972 to 1999 US commercial fisheries lost over 18 million dollars every year due to the poor water quality (National Science Foundation, 2000).

 

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How is it developed?

Under warm and excessive nutrient conditions (e.g., introduction of nitrogen and phosphorus), algae in the lake starts to grow rapidly. In most healthy lakes, all depths are well oxygenated and the species in lakes are diverse. The excessive nutrient loads leads to the dominance of algae to the lakes, in other word, algae bloom. Massive algae bloom in the surface results in water turbidity increasing therefore the sunlight is blocked from underwater plants. Additionally, algae in the lakes has a short lifespan and depletes the oxygen in water causing a death zone along the water column (hypoxia); some algae can release toxins which are deadly to fish (Hallegraeff, 1993). In this stage the amount of fishes along with aquatic plants decreases rapidly. The healthy, well-oxygenated and clear lake becomes turbid, unsightly with few species alive and a disgusting smell.

 

What happens to ecosystem within the lake?
1The submerged aquatic plants which are adapted themselves to original lake conditions (e.g. high concentration of chlorophyll) are almost wiped out from the lakebed during the algae bloom (Jupp and Spence, 1977). In the case of Taihu lake in China, the area covered by submerged aquatic plants was over 530 km2 which reduced to around 300 km2   in 2009 (Qin et al., 2012).

The decreasing amount aquatic plants would have an impact to the zooplanktons. Less coverage of submerged aquatic plants on lakebed means less refuge capacity provided for zooplanktons (SCHRIVER et al., 1995). Therefore, besides the pressure of hypoxia, zooplanktons are struggling to survive at high predation risk.

One pronounced impact of lake eutrophication is the decreasing trend of overall fish population along with rising algal population as oxygen depleted environment is no longer able to hold big fish population as a healthy lake. Aparting from decreasing quantity of fish community, the fish community quality is also under threat. Generally, highly eutrophic lakes often are dominated by ferocious fish species such as carp (Lee and Jones, 1991). They are more adapted to the poorly oxygenated environment and they are voracious predator of zooplanktons that eat algae, which is an enhancing factor of lake eutrophication (Reinertsen et al., 1990). Decreasing fish community diversity could also happen when low oxygen condition driving deep-water living fish coming to open water under oxygen pressure which result in hybrid with open water fish.

 

Human interference to the ecosystem

Under such environmental pressure, countries like China decides to apply biotic approach to solve the algae bloom causing by eutrophication. Deploying algae-munching fish is well-known as approach to regulate algae population (Andersson et al., 1978). However, massive releasing algae-munching fish would dramatically changing the composition of current aquatic community leading unpredictable problems in future.

 

 

 

References

Andersson, G., Berggren, H., Cronberg, G. and Gelin, C. (1978). Effects of planktivorous and benthivorous fish on organisms and water chemistry in eutrophic lakes. Hydrobiologia, 59(1), pp.9-15.

Hallegraeff, G. (1993). A review of harmful algal blooms and their apparent global increase*. Phycologia, 32(2), pp.79-99.

Jupp, B. and Spence, D. (1977). Limitations on Macrophytes in a Eutrophic Lake, Loch Leven: I. Effects of Phytoplankton. The Journal of Ecology, 65(1), p.175.

Lee, G. and Jones, A. (1991). Effects of Eutrophication on Fisheries. Reviews in Aquatic Science, [online] 5(3). Available at: http://www.gfredlee.com/Nutrients/Effects_Eutroph_Fisheries.pdf             [Accessed 22 Mar. 2017].

McKinnon, J. and Taylor, E. (2012). Biodiversity: Species choked and blended. Nature, 482(7385), pp.313-314.

National Science Foundation, (2000). Estimated Annual Economic Impacts from Harmful Algal Blooms (HABs) in the United States. [online] National Science Foundation. Available at:                       http://www.whoi.edu/cms/files/Economics_report_18564_23050.pdf [Accessed 22 Mar. 2017].

Qin, B., Gao, G., Zhu, G., Zhang, Y., Song, Y., Tang, X., Xu, H. and Deng, J. (2012). Lake eutrophication and its ecosystem response. Chinese Science Bulletin, 58(9), pp.961-970.

Reinertsen, H., Jensen, A., Koksvik, J., Langeland, A. and Olsen, Y. (1990). Effects of Fish Removal on the Limnetic Ecosystem of a Eutrophic Lake. Canadian Journal of Fisheries and Aquatic             Sciences, 47(1), pp.166-173.

SCHRIVER, P., BOGESTRAND, J., JEPPESEN, E. and SoNDERGAARD, M. (1995). Impact of submerged macrophytes on fish-zooplanl phytoplankton interactions: large-scale enclosure                         experiments in a shallow eutrophic lake. Freshwater Biology, 33(2), pp.255-270.

 

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Caring for the Community – How Climate Change is Impacting You!

Posted on by Kirsty State

Global warming has resulted in many species responding and behaving differently.  These changes can impact communities of plants, animals, people, in fact, all species that interact with each other within an environment.

Responses by different species to climate change are all connected through the interactions and shared resources of an ecosystem.  Overall earlier life events, such as flowering, feeding and hatching, are being recorded (Walther, 2010).  However, species do not respond equally to environmental changes.  This can result in timings of species interactions being off as a result of varying degrees of responses to temperature changes

The species found at certain locations are determined by three “filters”:

  • Dispersal
  • Environmental
  • Interactions

These filters are based around interacting species and their tolerance to specific environmental conditions (Götzenberger et al., 2012).  Global warming can be seen as an environmental filter (Weiher et al., 1998).  The increase in temperature could result in species being more or less tolerant of the increased temperature and therefore could change the collection of species in a community.

Climate change is occurring all over the planet, with certain ecosystems being particularly sensitive to it…

Take, for example, the tundra.  This is the area that borders the arctic, where species have to adapt to low temperatures with high variation.  Warming can result in many changes in this area.  Evidence from Alaska shows that climate change can influence land cover (Hinzman et al., 2005). This is through the increasingly more temperate climate, which allows species to grow in less hostile areas which were previously too cold or dry.

rein

Reindeer herd moving across their snowy calving grounds in the Mackenzie Delta, Canada (Dory, n.d)

Reindeer and Caribou species have been increasing in number in northern latitudes.  These play an important role in communities as they are often the largest, most numerous herbivores in an area.  As seen in the diagram below, the species are both affected by climate change impacts on the ecosystem as well as changing the ecosystem themselves.  Their impact on the environment has the potential to cause a vegetation transition (Bernes et al., 2015).  This could result in a knock on effect to other species that also feed off the vegetation eaten by Reindeer and Caribou.

flow-diagram

Flow diagram showing how increased temperatures affects vegetation and large herbivores

Another example is the plant-pollinator relationship that is disrupted by increasing temperature.  Both pollinators and the plants they pollinate, are changing their feeding and flowering times, respectively, at similar rates.  However, these rates are not exactly equal, resulting in a mismatch in the timings (Hegland et al., 2009).  Consequences of this mismatch are that pollination is not as efficient as it could be and that both plant and pollinators numbers are at risk.  This can have bottom up effect on the ecosystem, especially on species (such as humans) that rely on crops that are pollinated as a source of food (Walther, 2010).

bee-and-flower

Bumblebee pollinating a Dahlia ‘Moonfire’ plant (Photo by Kirsty State, 2015).

From these case studies it is important to note that not only is climate change impacting specific species that respond to temperature change, but through a network of communities and interactions within an ecosystem, it can indirectly affect us all.

 

 

Word count: 494

References

Bernes, C., Bråthen, K.A., Forbes, B.C., Speed, J.D. and Moen, J., 2015. What are the impacts of reindeer/caribou (Rangifer tarandus L.) on arctic and alpine vegetation? A systematic review. Environmental Evidence, 4(1), p.1-26.

Dory, N., n.d.  The reindeer of the Mackenzie Delta, Northwest Territories. [photograph] Available at: <http://www.nicolasdory.com/reindeer-of-the-mackenzie-delta/> [Accessed 17 March 2017].

Götzenberger, L., de Bello, F., Bråthen, K.A., Davison, J., Dubuis, A., Guisan, A., Lepš, J., Lindborg, R., Moora, M., Pärtel, M. and Pellissier, L., 2012. Ecological assembly rules in plant communities—approaches, patterns and prospects. Biological reviews, 87(1), pp.111-127.

Hegland, S.J., Nielsen, A., Lázaro, A., Bjerknes, A.L. and Totland, Ø., 2009. How does climate warming affect plant‐pollinator interactions? Ecology letters, 12(2), pp.184-195.

Hinzman, L.D., Bettez, N.D., Bolton, W.R., Chapin, F.S., Dyurgerov, M.B., Fastie, C.L., Griffith, B., Hollister, R.D., Hope, A., Huntington, H.P. and Jensen, A.M., 2005. Evidence and implications of recent climate change in northern Alaska and other arctic regions. Climatic Change, 72(3), pp.251-298.

Walther, G.R., 2010. Community and ecosystem responses to recent climate change. Philosophical Transactions of the Royal Society B: Biological Sciences, 365(1549), pp.2019-2024.

Weiher, E., Clarke, G.P. and Keddy, P.A., 1998. Community assembly rules, morphological dispersion, and the coexistence of plant species. Oikos, 81(2), pp.309-322.



Addressing the Elephant in the Room: A look into the Global Loss of Megafauna

Posted on by Julia Daly

In the light of the current epoch, the Anthropocene, being classified as a sixth mass extinction (Pievani, 2014), losses in biodiversity and its effects on ecosystems, from which humans directly benefit, has had a lot of scientific attention (Diaz et al., 2006). However, only recently has there been a focus on the global loss of terrestrial megafauna; larger bodied mammals of mass greater than 1000kgs (Ripple et al., 2015). In March 2014, the University of Oxford hosted the first ever international conference on ‘Megafauna and Ecosystem Functions’ (Malhi and Doughty, 2015) to address this global issue. Terrestrial megafauna, are under threat from human caused habitat loss and fragmentation (Segan et al., 2016), due to land-use change, such as agricultural expansion and deforestation (Ripple et al., 2015, 2016). Although this is a global issue, the heaviest decline in megafauna is concentrated in sub-saharan African and south-east Asia (Figure 1).

screen-shot-2017-03-21-at-23-27-08

 

Figure 1– Global representation of the number of declining megafauna worldwide (Ripple et al., 2016)

Environmental change through the alteration of habitats puts the larger sized megafauna at a higher risk of extinction as they need larger, non-fragmented habitats, and have slower life-histories (Ripple et al., 2016), taking longer to reproduce.

Why focus on megafauna? Extensive research into losses of biodiversity and its effect on ecosystems has revealed one thing for certain: the importance of functional traits. Biodiversity can ensure the functioning of an ecosystem if its functional composition is adequate to maintain the system, having organisms with specific traits (Diaz, et al., 2006). Much like a well-working machine, all the pieces are needed for it to run. The more important parts of this machine, or ecosystem, are the megafauna, as many act as ecosystem engineers (Smith et al., 2015) and keystone species (Ripple et al, 2016). Megafauna fill the roles- niches- in the ecosystem that would otherwise not be filled. The effect of their loss will be felt by the whole ecosystem as impacts will filter down through trophic levels and the food web (Svenning et al., 2015).

The African elephant alters ecosystem structure and composition, through various behaviour including uprooting and debarking of trees (Mograbi et al., 2017), seed dispersal and alteration of habitats (Ripple et al, 2015). They have overall effects on the ecosystem in which they live, which indirectly affects the other organisms that depend on that ecosystem (Figure 2). Land-use change has caused a decline in African elephants (Ripple et al., 2015); a key player in ecosystem functioning. The ecosystem may therefore begin to fall apart without it’s key piece (Smith et al., 2015). This is just one example of how the loss of a single species can have significant implications, highlighting the severity of impacts if several species were to be lost.

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Figure 2– Diagram demonstrating how the African elephant can effect the ecosystem and the other organisms they impact (Ripple, et al., 2015).

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Figure 3 – Diagram and explanation of the interactions between global changes, human activities and ecosystems (Chapin III, et al., 2000).

These global changes can be felt not only by the animals, that depend on the megafauna, but by humans as well. Figure 3 shows how humans will also ultimately feel the effects of the global changes they cause due to their effects on ecosystems.

 

 

References:

Chapin III, F. S., Zavaleta, E. S., Eviner, V. T., Naylor, R. L., Vitousek, P. M., Reynolds, H. L., Hooper, D. U., Lavorel, S., Sala, O. E., Hobbie, S. E., Mack, M. C., Diaz, S., 2000. Consequesnce of changing biodiversity. Nature 405, pp 234-242.

Diaz, S., Fargione, J., Chapin III, F. S., Tilman, D., 2006. Biodiversity Loss Threatens Human Well-Being. PLoS Biol 4(8): e277

Malhi and Doughty, 2015. Megafauana and Ecosytem Function: Learning from the Giants. Available at < http://www.eci.ox.ac.uk/news/2015/1026-megafauna.html> [Accessed: 21st March 2017]

Morgabi, P., Asner, G. P., Witkowski, E. T. F., Erasmus, B. F. N., Wessels, K. J., Mathieu, R., Vaughn, N. R., 2017. Humans and elephants as treefall drivers in African savannas. Ecography 40: 001-011

Pievani, T., 2014. The sixth mass extincton: Anthropocene and the human impact on biodiversity. Rend. Fis. Acc. Lincei 25: 85-93

Ripple, W. J., Newsome, T. M., Wolf, C., Dirzo, R., Eceratt, K. T., Galetti, M., Hayward, M. W., Kerley, G.I.H., Levi T., Lindsey, P. A., Macdonald, D. W., Malhi, Y., Painter, L. E., Sandom, C. J., Terborgh, J & Van Valkenburgh, B, 2015. Collapse of the world’s largest herbivores. Science Advances, 1: e1400103, pp 1-12

Ripple, W. J., Chapron, G., López-Bao, J. V., Durant, S. M., Macdonald, D. W., Lindsey, P. A., Bennett, E. L., Beschta, R. L., Bruskotter, J. T., Campos-Arceiz, A., Corlett, R. T., Darimont, C. T., Dickman, A. J., Dirzo, R., Dublin, H. T., Estes, J. A., Everatt, K. T., Galetti, M., Goswami, V. R., Hayward, M. W., Hedges, S., Hoffmann, M., Hunter, L. T. B., Kerley, G. I. H., Letnic, M., Levi, T., Maisels, F., Morrison, J. C., Nelson, M. P., Newsome, T. M., Painter, L., Pringle, R. M., Sandom, C. J., Terborgh, J., Treves, A., Van Valkenburgh, B., Vucetich, J. A., Wirsing, A. J., Wallach, A. D., Wolf, C., Woodroffe, R., Young, H. and Zhang, L., 2016. Saving the World’s Terrestrial Megafauna. BioScience, 60 : 10, pp 807-812

Segan, D., B, Murray, K. A., Watson, J. E. M., 2016. A global assessment of current and future biodiversity vulnerability to habitat loss-climate change interactions. Global Ecology and Conservation 5, pp 12-21

Smith, F. A., Doughty, C. E., Malhi, Y., Svenning, J., Terborgh, J., 2015. Megafauna in the Earth System. Ecography 39: 2, pp 99-108

Svenning et al., 2015. Science for a wilder Anthropocene: Synthesis and future directions for trophic rewilding research. PNAS 114 (4), pp 898-906

 

 

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Diamonds aren’t Forever, as Villainous Tourists have a ‘License to Kill’ the World’s Coral Reefs

Posted on by Thomas Manktelow

Tourism is killing coastlines worldwide, destroying crucial coral reefs and the immense diversity within these ecosystems. Humans are irreversibly changing the marine environment!

There is a modern urge to travel the world; tropical, coastal areas increasingly visited for the sun and climate. More money in these regions puts natural systems at-risk, increased development and uncontrolled tourism affecting ecosystems such as coral reefs. Tourism has the ability to severely degrade coral reefs, introduced below (4earthTV, 2016).


Akumal Case Study

Akumal, Mexico, is an example of a coastline and reef ravaged by tourism. The number of hotel rooms in the region has increased by 80,000 in the last 30 years (Gil et al, 2015).
I have seen for myself the extent of the local environment change, which has had obvious negative effects on the health of the Mesoamerican barrier reef (BBC Earth, 2014).

In Akumal’s popular snorkeling areas, coral cover declined by 79% between 2011 and 2014. Globally, holiday activities have negative effects on the coral and on the native reef species (Gil et al, 2015). Turtle and shark populations suffer increased stress as tourism and tourists dominate the coastline (Constantine, 2001). Coral reefs are very sensitive to rapid tourism development, the popularity of these areas increasing algal cover and coral disease in the community (Garpow, 1999).

Tourism and boat traffic in Akumal Bay, Akumal (Photo: J. Houston)
Tourism and boat traffic in Akumal Bay, Akumal (Photo: J. Houston)

Hotel Pollution

Another consequence of global change are the septic tanks from growing hotel complexes, which feed coral reefs with nutrients, boosting the growth of algae and negatively changing the system. This clouds the water, meaning sunlight cannot reach the coral, causing unhealthy reef conditions (Garpow, 1999). Tourists are a huge environmental change impacting coral reefs. Coastal resorts attract the greatest number of tourists annually, often because of our growing desire to view coral reefs (Davenport & Davenport, 2006).

 

SCUBA Divers and Snorkelling

Worldwide, SCUBA divers and swimmers can severely damage the reef – in crowded areas, coral contact can lead to 100% mortality (Reef Resilience, 2016), inflicting abrasion and tissue loss (Davenport & Davenport, 2006). Tourists can also suffocate the coral, stirring up silt and encouraging algal domination. Coral reefs are also experiencing more boat traffic, which can disrupt coral communities, upsetting species interactions. Using boat anchors on the reef can damage the coral for decades, lowering reproductive health and species fitness (Rogers and Garrison, 2001).

Left: Snorkeler touching native turtle (Photo: J.Bartoszec, 2010). Right: Brain coral suffering anchor damage (Photo: Z. Livnat)
Left: Snorkeler touching native turtle (Photo: J.Bartoszec, 2010). Right: Brain coral suffering anchor damage (Photo: Z. Livnat)


The Future of Coral Reefs

There are global plans to increase tourism around coral reefs, building additional hotels. Human pollution will increase; sun-cream and E. coli contamination expected to impact reef health. Marine turtles are also developing tumours from a tourism-borne virus, demonstrating the reduced health of coral reefs and the species within them; all because of tourism (Sanchez-Navarro Russell, 2016).

Coral reefs across the world are experiencing problems associated with tourism. Fifty years ago reefs were untouched; only in the last 30 years have coral reefs become a primary tourist attraction. The coastline has changed so dramatically that slow-growing coral and the species within them cannot adapt fast enough and are suffering greatly.

Tourism has the potential to kill existing coral reefs; therefore, it is our responsibility to manage coastlines with greater effect, and as tourists, show greater respect towards the marine environment.

 

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References

BBC Earth. (2014). The Struggle to Save the Caribbean’s Huge Barrier Reef. Available: http://www.bbc.co.uk/earth/story/20141128-the-other-great-barrier-reef. Last accessed 13th March 2017

Constantine (2001), Increased Avoidance of Swimmers by Bottlenose Dolphins (Tursiops truncatus) due to Long-Term Exposure to Swim-With-Dolphin Tourism, Marine Mammal Science. 17 (4), p689-702.

Davenport and Davenport (2006), Impact of Tourism and Personal Leisure Transport on Coastal Environments: A Review. Estuarine, Coastal and Shelf Science. 67, p280-292.

Garpow, W (1999), Sustainability Indicators Regarding Tourism Development and Coral Reef Conservation: A Case Study of Akumal in the Caribbean, Proceedings of the 1999 Northeastern Recreation Research Symposium. P23-29.

Gil et al (2015), Rapid Tourism Growth and Declining Coral Reefs in Akumal Mexico, Marine Biology. 162 (11), p2225-2233

Reef Resilience (2016), Tourism and Recreational Impacts. Available: http://www.reefresilience.org/coral-reefs/stressors/local-stressors/coral-reefs-tourism-and-recreational-impacts/. Last accessed 13th March 2017.

Rogers and Garrison (2001), Ten Years after the Crime: Lasting Effects of Damage from a Cruise Ship Anchor on a Coral Reef in St. John, U.S. Virgin Islands. Bulletin of Marine Science. 69 (2), p793-803.

Sanchez-Navarro Russell (2016), Akumal Suffering from Unsustainable Growth. Available: http://mexiconewsdaily.com/opinion/akumal-suffering-from-unsustainable-growth/. Last accessed 13th March 2017.

4earthTV. (2016). Coral Reef Conservation: 4earthTV. Available: https://www.youtube.com/watch?v=OGcnzggMqKA. Last accessed 22nd March 2017.



Fragmentation devastation: Why terrestrial habitats around the globe are being pushed over the edge.

Posted on by Dmitri Dharmasena

Habitat fragmentation is a term describing the process by which a large  habitat is broken up into numerous smaller habitats of decreased area and size, separated by a matrix of new unfamiliar habitat types – driven by the action of habitat loss (Didham, R.K., 2010). The loss of habitat through fragmentation is thought to be one of the main drivers of global biodiversity loss and can be either naturally occurring (climate change, volcanism, fires etc.) or human induced.

 

“70% of remaining forest is within 1km of the forest edge..” (Haddad et al, 2015)

 

Figure 1: The process of habitat fragmentation shown over time. Black regions represent areas of habitat and white regions represent newly formed matrix habitats. (Source: Fahrig, 2003).
Figure 1: The process of habitat fragmentation shown over time. Black regions represent areas of habitat and white regions represent newly formed matrix habitats. (Source: Fahrig, 2003).

 

What are the major effects of habitat fragmentation?

A long term global forest fragmentation study revealed that decreases in fragment area and an increase in fragment isolation, generally causes a drop in the abundance of:

  • Mammals
  • Birds
  • Insects
  • Plants

In tropical forests, reduced fragment sizes led to an increase in the portion of edge habitat exposed to unfamiliar surroundings. Following the increase in edge habitat, a shift in the physical environment was observed which caused a subsequent loss in the oldest and largest trees from these fragments, which had knock-on impacts on the wider community and specifically insect community compositions (Haddad et al, 2015).

Figure 2: Fragmented forests in the tropics.
Figure 2: Forest fragmentation in the tropics (Source: ALERT, 2015).

Fragmentation also effects communities through alterations of predator-prey interactions. It has been theorised that specialist predators are affected more severely by the fragmentation than their prey leading to a lower specialist predator abundance (Ryall & Fahrig, 2006). Generalist predators whom live predominantly within the matrix are thought to be benefited by increased fragmentation, so long as the new matrix is able to provide the generalist predator with alternative resources (Ryall & Fahrig, 2006). These adjustments will have cascading effects down through communities due to a rise or fall in the populations of top predators and their prey.

 

What is being done to help?

Case study: The Bhutanese Tiger corridor

One mechanism that has been implemented around the world is the use of ‘wildlife corridors’ (Silveira et al, 2015), which serve to reconnect fragmented patches of habitat. The Bhutanese Tiger corridor, from Northern India into Bhutan (see figure 2) has proven that this method does work. The corridor connects isolated Tiger habitats that now allow free passage for Tigers and other community species across a far greater space of land. Since its introduction the Bhutanese Tiger population has risen by more than a third of its previous population estimate.

Figure 2: A map visualising the Tiger corridor implemented between North Eastern India and Bhutan.
Figure 3: A map visualising the Tiger corridor implemented between North Eastern India and Bhutan (Source: Broad, 2012).

 

Fragmentation induces diverse changes that progressively filter through ecosystems. It  considerably lowers species richness of both plants and animals and in many cases it has impacted the structure and make up of entire animal communities. Habitat fragmentation is therefore an extreme threat to virtually all terrestrial biodiversity. Consequently, conservation efforts and habitat restoration projects must being immediately in order to prevent catastrophic losses and extinctions of some of the most iconic species on earth.

 

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References

  • ALERT, (2017). Forest fragmentation in the tropics.. [image] Available at: http://alert-conservation.org [Accessed 21 Mar. 2017].
  • Broad, M. (2012). NE Indian Tiger corridor. [image] Available at: http://pictures-of-cats.org/the-tigers-of-bhutan.html [Accessed 20 Mar. 2017].
  • Didham, R.K., 2010. Ecological consequences of habitat fragmentation. eLS.
  • Fahrig, L., 2003. Effects of habitat fragmentation on biodiversity. Annual review of ecology, evolution, and systematics, 34(1), pp.487-515.
  • Haddad, N.M., Brudvig, L.A., Clobert, J., Davies, K.F., Gonzalez, A., Holt, R.D., Lovejoy, T.E., Sexton, J.O., Austin, M.P., Collins, C.D. and Cook, W.M., 2015. Habitat fragmentation and its lasting impact on Earth’s ecosystems. Science Advances, 1(2).
  • Ryall, K.L. and Fahrig, L., 2006. Response of predators to loss and fragmentation of prey habitat: a review of theory. Ecology, 87(5), pp.1086-1093.
  • Silveira, L., Sollmann, R., Jácomo, A.T., Diniz Filho, J.A. and Tôrres, N.M., 2014. The potential for large-scale wildlife corridors between protected areas in Brazil using the jaguar as a model species. Landscape ecology, 29(7), pp.1213-1223.

 



In hot water: a planet surviving on thin ice.

Posted on by Katherine Turnbull

We’ve all seen it, the iconic lone polar bear stranded on the only ice in view. It has become the poster-boy for climate change (CC). CC is impacting almost every habitat on earth, but is the impact it’s having on Arctic organisms as bad as we’re made to believe?

Source: Hennesseysview.com
Source: Hennesseysview.com


The climate is changing. This mainly due to human’s releasing greenhouse gases into the atmosphere, causing the global phenomenon, CC. With increasing temperatures, melting ice stocks and changing ocean currents and weather, CC is one of the greatest challenge facing our generation (Steinfield et al., 2006).

The Arctic is expected to experience the most dramatic change out of any place on Earth (WWF, n.d). It is warming at twice the rate of the globe, a trend set to continue with global temperatures predicted to increase 1.4-5.8°C between 1990-2100 (Naware, 2015; Vihma, 2014). However, worryingly the so-far moderate warming has already impacted Arctic organisms; directly, through the immediate impacts, but also indirectly, by changing ecological interactions, such as predation and habitat distribution (Nahrgang et al., 2014). Heralding changing ecosystems and communities in the region.

It’s getting hot in here, shame polar bears can’t take off their clothes…

As temperature continues to rise, animals are moving poleward, to escape the heat or expand their territories (IPCC, 2007). This has caused ‘the clash of the animals’. For example, Red Foxes are migrating poleward placing their northern counterpart the Arctic Fox under threat (Post et al., 2009). The Red Fox is bigger and more aggressive, leading to a decline in populations of Arctic Foxes (Merchant, 2011). These invasions alter communities and carry threats of hybridization and increased disease (FAO, 2012). As the globe continues to warm, we will witness more unprecedented clashes like this…

Shame cuteness doesn't count for anything in nature right? Source: Foxesworld.com/ pintrest.com
Shame cuteness doesn’t count for anything in nature right? Source: Foxesworld.com/ pintrest.com

Increasing temperatures are altering the life-cycle events of birds, insects and plants. Bringing forward migration and reproduction. The Buff-breasted sandpiper is now nesting 10-days earlier due to increasing temperatures in the Arctic (Hattam, 2009).

‘If you meet a woman start talking about global warming, it’s a real icebreaker…’

The extent and thickness of ice coverage in the Arctic has reduced by 700,000m2 compared to historical levels (1981-2010) (EPA, 2016). This has negatively impacted species that rely on the ice for prey, reproduction and predator avoidance (Post et al., 2009). This includes Walruses, who use sea ice to rest and reproduce, but now use land instead (Badore, 2014). This has been linked to decreasing populations, meaning it is so-far unclear if they will be able to successfully adapt. Changing extent and timing of sea ice formation impacts ecosystem resilience by affecting lower levels of the food chain, thereby impacting predators such as Polar Bears and Walruses who depend on them to survive (Derocher, 2004).

Walrus's resting on the beach instead of ice, their usual habitat, due to decreased ice stocks in the Arctic. Source: Walrus-world.com / Treehugger.com
Walruses resting on the beach instead of ice, their usual habitat, due to decreased ice stocks in the Arctic. Source: Walrus-world.com / Treehugger.com

So yes, the impacts are bad and possibly irreversible. The entire globe will be impacted through CC effecting the services the Arctic provides us with, such a climate regulation and natural resources (Post et al., 2009). So, what happens in the Arctic doesn’t just stay in the Arctic…

[Word count: 500]

References:

Badore, M. (2014). This is what it looks like when 35,000 walrus can’t find enough sea ice. [Online] [Last accessed: 20/03/2017] [Accessed at: http://www.treehugger.com/climate-change/what-it-looks-when-35000-walrus-cant-find-enough-sea-ice.html]

Derocher, A. (2004). Polar Bears in a Warming Climate. Integrative and Comparative Biology, 44(2), pp.163-176.

EPA. (2016). Climate Change Indicators: Arctic Sea Ice. [Online] [Last accessed: 19/03/2017] [Accessed at: https://www.epa.gov/climate-indicators/climate-change-indicators-arctic-sea-ice]

FAO. (2012). Wildlife in a changing climate. [Pdf]. [ Last accessed: 12/02/2017] [Accessed at:
http://www.fao.org/docrep/015/i2498e/i2498e.pdf]

Hattam, J. (2009). ‘Unsung’ Species Stressed by Climate Change Too. [Online]. [Last accessed: 20/03/2017] [Accessed at: http://www.treehugger.com/natural-sciences/unsung-species-stressed-by-climate-change-too.html]

IPCC. (2007). Climate Change 2007: Working Group II: Impacts, Adaptation and Vulnerability. [Online] [Last accessed: 18/02/2017] [Accessed at: https://www.ipcc.ch/publications_and_data/ar4/wg2/en/ch1s1-3-5-2.html]

Merchant, B. (2011). Foxfight: Climate Change Causing Arctic & Red Foxes to Clash. [Online]. [Last accessed: 19/03/2017] [Accessed: http://www.treehugger.com/clean-technology/foxfight-climate-change-causing-arctic-red-foxes-to-clash.html]

Nahrgang, J., Varpe, Ø., Korshunova, E., Murzina, S., Hallanger, I., Vieweg, I. and Berge, J. (2014). Gender Specific Reproductive Strategies of an Arctic Key Species (Boreogadus saida) and Implications of Climate Change. PLoS ONE, 9(5), p.e98452.

Naware, R. (2015). 10 reasons why climate change in the Arctic affects us all. [Online]. [Last accessed: 11/03/2017] [Accessed at: https://www.earthhour.org/blog/10-reasons-why-climate-change-the-arctic-affects-us-all]

Post, E., Forchhammer, M., Bret-Harte, M., Callaghan, T., Christensen, T., Elberling, B., Fox, A., Gilg, O., Hik, D., Hoye, T., Ims, R., Jeppesen, E., Klein, D., Madsen, J., McGuire, A., Rysgaard, S., Schindler, D., Stirling, I., Tamstorf, M., Tyler, N., van der Wal, R., Welker, J., Wookey, P., Schmidt, N. and Aastrup, P. (2009). Ecological Dynamics Across the Arctic Associated with Recent Climate Change. Science, 325(5946), pp.1355-1358.

Schofield, O., Ducklow, H., Martinson, D., Meredith, M., Moline, M. and Fraser, W. (2010). How Do Polar Marine Ecosystems Respond to Rapid Climate Change? Science, 328(5985), pp.1520-1523.

Steinfeld, H. (2006). Livestock’s long shadow. 1st ed. Rome: Food and Agriculture Organization of the United Nations. Pp. xxi

Vihma, T. (2014). Effects of Arctic Sea Ice Decline on Weather and Climate: A Review. Surveys in Geophysics, 35(5), pp.1175-1214.

WWF. (N.d). Factsheet: Effects of climate change on arctic ecosystems. [Online]. [Last accessed: 10/03/2017] [Accessed at: https://c402277.ssl.cf1.rackcdn.com/publications/396/files/original/
Effects_of_Climate_Change_on_Arctic_Ecosystems_fact_sheet.pdf?1345753524]

 

 

 



Marine Aliens Are Invading…And They Are Not Coming In Peace!

Posted on by Anonymous

      

Biological invasions are the introduction of non-native (alien) species into an ecosystem (fig. 1), and is a major cause of global change (Ruiz et al., 1997). Marine ecosystems are particularly affected due to ballast water in shipping acting as a means of transport, and as shipping increases so do the invasions (Seebens et al., 2013). However, the likelihood of new introductions depends not only on shipping intensity but also on other ecological and environmental factors (Keller et al., 2010). Marine invasions are usually devastating to ecosystems because most are difficult or impossible to remove/control (Molnar, 2008).  Most marine invasions are not deliberate and impact the ecosystem negatively, however, not all invasions are bad and some are even on purpose to for human gain e.g. pest control.

Lyretail Anthias in Coral Reef

                              Figure 1. Coral reefs are delicate ecosystems and are very  susceptible to marine invasions

It is often marine ecosystems in coastal areas, with harbours/ports, that are the most affected (or at least first) by marine invasions (Seebens et al., 2013), which is intensified by increased pollution often found there. A study by Molnar et al. (2008) focused on the impact marine invasions had on coastal ecosystems (fig. 2) and identified 57% of species were ‘harmful’ to the ecosystem. Also identified, was that only 16% of marine ecoregions (classification used for marine coastal environments) had no reported marine invasions, which was even thought to be inflated. This revealed the true extent and seriousness of marine invasions and their negative impacts on ecosystems.sadfasd                                             Figure 2. Map of ecoregions and their number of known alien species                                                                                                                    

The sea walnut (fig. 3) is a classic example of an introduced species via ballast water. It was first introduced into the Black sea in the early 80s, later spreading into the Caspian Sea in the 90s, where it increased to dramatic numbers with a negative impact on the ecosystem (Roohi et al., 2008).  It was thought to be the main cause of a decrease in anchovy, and other fish, stocks through competition and by directly consuming anchovy fish eggs and larvae. This change in fish also effects those at the top of the food chain as less prey is available to them; and those at the bottom (tiny cells that photosynthesise like plants) that use nutrients in the water; which the sea walnut significantly changes when present in large numbers.

jelly-6Figure 3. Sea walnuts (Mnemiopsis leidyi) are approximately 10 cm in length

Ballast water is not the only way of introducing non-native species; as seen with the Indo-Pacific lionfish (fig. 4). The coral reef inhabiting lionfish was introduced, via the aquarium trade, into the southeast of the United States in the mid-80s (Albins & Hixin, 2007). Lionfish numbers have since increased due to being opportunistic feeders, possessing venomous spines, fishing of native predators and lack of fishing of themselves. It is predicated, and already being seen in, that lionfish will severely degrade coral reefs by feeding on parrotfish and other herbivores, who prevent seaweed outcompeting corals. They also compete and/or prey on mid-sized predators which destabilises coral reef populations, therefore impacting the delicate ecosystem balance.

lionfish-3Figure 4. Red Lionfish (Pterois volitans) and its array of venomous spines

These are just some examples of how marine invasions have had devastating consequences to the ecosystem, by disrupting the natural balance in place. These consequences also impact services to humans, and is why so much scientific research is taking place on biological invasions in marine ecosystems and how to control them

[496 words]

References

Albins, M. A. & Hixon, M. A. (2013) Worst case scenario: potential long-term effects of invasive predatory lionfish (Pterois volitans) on Atlantic and Caribbean coral-reef communities, Environmental Biology of Fishes, 96(10-11); 1151-1157

Dirscherl, D. (2015) Coral reefs are delicate ecosystems and are very susceptible to marine invasions, Available at http://www.travelandleisure.com/travel-tips/responsible-travel/great-barrier-reef-severe-bleaching-photos [Accessed 19th March 2017]

Johanhansson, L (2015) Sea walnut (Mnemiopsis leidyi), Available at http://www.devbio.biology.gatech.edu/?page_id=6890 [Accessed 19th March 2017]

Keller, R. P. et al. (2010) Linking environmental conditions and ship movements to estimate invasive species transport across the global shipping network. Diversity and Distribtutions, 17(1); 93-102

Molnar, J. L. (2008) Assessing the global threat of invasive species to marine biodiversity, Frontiers in Ecology and the Environment, 6(9); 485-492

Molnar, J. L. (2008) Map of ecoregions and their number of known alien species, Available at http://ballast-outreach-ucsgep.ucdavis.edu/files/136965.pdf [Accessed 19th March 2017]

Present, N. (2016) Red Lionfish (Pterois volitans) with its array of venomous spines, http://nautika-present.com/2016/07/22/bright-colours-deep-sea [Accessed 19th March 2017]

Roohi, A. (2008) Impact of a new invasive ctenophore (Mnemiopsis leidyi) on the zooplankton community of the Southern Caspian Sea, Marine Ecology, 29(4); 421-434

Ruiz, G. M. (1997) Global invasions of marine and estuarine habitats by non-indigenous species: mechanisms, extent, and consequences, American Zoologist, 37(6); 621-632

Seebens, H., Gastner, M .T. & Blasius, B. (2013) The risk of marine bioinvasion caused by global shipping, Ecology letters, 16(6); 782-790



When Nelly The Mastodon packed her Trunk….

Posted on by William Townsend

The Mammoth Steppe

Image result for Mammoth steppe species
Figure 1. An artist’s rendition of the Mammoth Steppe

The “mammoth steppe” ecosystem existed approximately 11 thousand years ago, during the Pleistocene epoch (University of California Museum of Palaeontology, 2011). This ecosystem was typified by high species densities, highly productive vegetation and high levels of nutrient cycling. (Pleistocene Park, 2017). In appearance it was very similar to the modern tundra ecosystem seen in northern latitudes such as Iceland and Northern Canada. Within these ecosystems the predominant species were large herbivores; Steppe Bison (Bison priscus), Horses (Equus lambei), Musk ox (Boothrium bombifrons) and Mammoths (Mammuthus primigenius) (Guthrie, 1989; Merck, 2011) but other large herbivorous species included the woolly rhino and giant deer (Van Kolfschoten, 2007) were also present in less abundance.

Image result for beringia
Figure 2. The extent of the Mammoth Steppe across the landmass Beringia

Whilst this is not an exhaustive list of the species present, as exemplified by the fossil record presented in Cooper (2008), this megafaunal community provides a good example of the prevalent community assemblage of the ecosystem. An example of this ecosystem is “Beringia” the landmass present when the bed of the Bering sea was exposed linking Siberia and North America.

 

How The Mammoth Went Extinct And Took Its Habitat With It

There are two prevalent theories as to how species within these ecosystems went extinct; The impacts of Climate change and the impacts of overhunting by humans. In terms of “biogeographic population theory” these constitute the environmental and biotic constraints; the limits placed upon a species by the environment and by other species, however both are driven by a change in climate. The direct impact of environmental change was increased seasonal variation and widely fluctuating climates, putting stress on many species and limiting populations. Indirectly this increased the pressure between species, with declines in food sources due to altered growing seasons resulting in resident humans relying more heavily on large mammal hunting. The combination of environmental and biotic pressures it is thought, resulted in the extinction of many large  grazing species in this ecosystem and it is argued, resulted in a shift away from the tundra and towards higher productivity systems (Pleoistocene Park, 2017).

 

Why Does It Matter?

Image result for tundra map
Figure 3. The modern extent of the tundra ecosystem

When applied to modern tundra ecosystems, which share much of the same range as the “Mammoth steppe”, these theories could have several implications. With modern human driven climate change, species that are highly sensitive to changes like snow cover reduction and rising temperatures in the modern day tundra ecosystems could be at risk. This is visible in Caribou populations, which show a decline correlated with rising temperature and rainfall (Vors and Boyce, 2009) and who’s populations may be influenced by plant community shifts driven by abiotic changes.

Musk ox populations also show variability as a result of forage ability, habitat availability, and infectious diseases. increasing temperature and humidity (Ytrehus, et al., 2008).

Image result for tundra species
Figure 4. An artist’s rendition of the tundra ecosystem

With the loss of such prevalent grazing herbivorous species could come a resultant ecosystem shift as seen during the Pleistocene quaternary extinction, and result in the loss of the modern tundra ecosystem.

Word Count: 495

 

Bibliography

Cooper, C.L. (2008) Pleistocene Fauna. Available at: http://www.uky.edu/OtherOrgs/KPS/poky/files/pokych10-01-29.pdf (Accessed: 1 March 2017).

Lenart, E.A., Bowyer, R.T., Hoef, J.V. and Ruess, R.W. (2002) ‘Climate change and caribou: Effects of summer weather on forage’, Canadian Journal of Zoology, 80(4), pp. 664–678. doi: 10.1139/z02-034.

Merck, J. (2011) Alaska 2007 – the mammoth Steppe. Available at: https://www.geol.umd.edu/~jmerck/alaska/alaska11pleistocene.html (Accessed: 1 March 2017).

Pleistocene Park (2017) Pleistocene park: Restoration of the mammoth Steppe Ecosystem. Available at: http://www.pleistocenepark.ru/en/background/ (Accessed: 1 March 2017).

University of California Museum of Paleontology (2011) The Pleistocene epoch. Available at: http://www.ucmp.berkeley.edu/quaternary/pleistocene.php (Accessed: 1 March 2017).

Van Kolfschoten, T. (2007) The collapse of the mammoth Steppe ecosystem. Available at: http://www.nwo.nl/en/research-and-results/research-projects/i/57/3357.html (Accessed: 1 March 2017).

Vors, L.S. and Boyce, M.S. (2009) ‘Global declines of caribou and reindeer’, Global Change Biology, 15(11), pp. 2626–2633. doi: 10.1111/j.1365-2486.2009.01974.x.

Ytrehus, B., Bretten, T., Bergsjø, B. and Isaksen, K. (2008) ‘Fatal pneumonia Epizootic in musk ox (Ovibos moschatus) in a period of extraordinary weather conditions’, EcoHealth, 5(2), pp. 213–223. doi: 10.1007/s10393-008-0166-0.



Undeniable, unequivocal, underwater.

Posted on by Sarah Mayson

Climate change is undeniable (don’t argue), unequivocal and impacting underwater ecosystems.

Figure 1: A coral reef before and after the occurrence of coral bleaching. Source: climate.gov
Figure 1: Goodness reefuss! The devastation of Coral Bleaching. Source: climate.gov

Expanding from ‘Finding Nemo’, coral reefs are diverse underwater ecosystems playing host to symbiotic algae called Symbiodinium (Baker, Glynn and Riegl, 2008). This symbiotic relationship is mutually beneficial; algae capture sunlight and perform photosynthesis providing oxygen and nutrients to coral, whilst coral provides algae with a protected environment and photosynthetic compounds. However, this relationship is vulnerable to climate change, existing exclusively within narrow temperature limits associated with shallow, sunlit waters (Frieler et al., 2012). When exposed to above-normal temperatures, stressed corals expel dinoflagellates (Symbiodinium) from its tissues exposing its bleach-white skeleton (‘witwoo’) in a process called Coral Bleaching(figure1&2).

Figure 2: The following schematic describes the coral bleaching process. If the stress-caused bleaching is not severe, coral have been known to recover. However, if the algae loss is prolonged and the stress continues, coral eventually dies. Source: Oceanservice.noaa
Figure 2: Back to shoal special! This educational schematic describes the coral bleaching process.  Source: Oceanservice.noaa

The IPCC (2007) reported with HIGH confidence that observed changes in marine systems are associated with rising ocean temperatures. This is obviously not linked to the average 0.8℃ global ‘human-induced‘ temperature rise between 1961-2010 (NOAA, 2016) (figure 3); yes I’m rolling my eyes. Average tropical sea surface temperature (SST) has risen by 0.7℃ since 1970 (NOAA, 2016; figure3), parallel to atmospheric temperatures and with considerable variability, from our friend El Nino (NOAA, 2016). This is ultimately driving Coral Bleaching.

Figure 3ab: It's getting hot in here...and coral are literally taking off their clothes.
Figure 3: It’s getting hot in here…and coral are literally taking off their clothes. Source: left: www.epa.gov/climate-indicators right:www.metoffice.gov.uk

Still not convinced?

Bleaching has been SCIENTIFICALLY-PROVEN to correlate with climate-induced temperature rise, notably after 1970. For example, a 35% increase in Caribbean bleaching incidence between 1980-1990 resulted from a 1℃ regional SST rise (Baker, Glynn & Riegl, 2008). Case-studies are summarised in figure4ab.

Figure 4ab: Documented case studies of worldwide bleaching. Since the early 1980s, episodes of coral reef bleaching and mortality, due to climate-induced ocean warming, have occurred almost annually with increased frequency and intensity. Africa remains to be an outlier and yet to report a coral bleach event. Source: Baker, Glynne and Riegl, 2008.
Figure 4ab: Is anywhere safe? Since the early 1980s, episodes of coral reef bleaching and mortality, due to climate-induced ocean warming, have occurred almost annually with increased frequency and intensity (Baker, Glynn & Riegl, 2008). 
Source: Baker, Glynn & Riegl, 2008.

The third global bleach was designated by the NOAA in 2016; the first (1998) decimated 16-19% of the world’s coral (NOAA, 2017). A strong el-Nino (2016-2017) worsened the bleach and as of February 2017, the on-going global bleach continues to be the longest and most prevalent on record (NOAA, 2017; figure5).

Figure 5: The NOAA coral reefs watch indicates bleaching heat stress continues to build. There is a 60% chance that the displayed heat stress levels will occur. Multiple coral reefs are experiencing Alert Level 1 and Alert Level 2 bleaching stress (associated with widespread coral bleaching and significant mortality). Source: https://coralreefwatch.noaa.gov/satellite/analyses_guidance/global_coral_bleaching_2014-17_status.php
Figure 5:  Uh oh Alert! (1 and 2). The NOAA coral reefs watch indicates bleaching heat stress continues to build with a 60% chance that the displayed heat stress levels will occur. Source: https://coralreefwatch.noaa.gov

The ecological impacts of coral bleaching and related mortality you say? I’ve chosen my favourites.

Figure 6. Clown fish keep their fronds close but their anemones closer. Source: cargocollective.com
Figure 6. Clown fish keep their fronds close but their anemones closer. Source: cargocollective.com

Coral reefs are underwater rainforests. Covering 1% of the ocean floor, they support a 1/4 of all ocean life by providing the foundations for complex food webs and essential nurseries, spawning, breeding and feeding habitats (Jones et al., 2004; Bellard et al., 2012). An 8-year study in Papua New Guinea saw a dramatic decline in coral cover and a parallel decline in fish biodiversity; 75% of reef species declined in abundance (Jones et al., 2004). Yes folks, this includes much loved ‘Nemo’, the Pomacanthidae family(figure 6).

Coral diseases (figure 7) have been observed to correlate with temperature anomalies and bleaching events (Weil, 2004). Bleaching in the US Virgin Islands (a piece of the Caribbean ‘disease-hotspot’), followed by a disease outbreak (2005), resulted in severe reef degradation; the amount of living coral cover decreased by 60% (Jackson et al., 2014). Reported impacts included a reduction in live coral cover and considerable changes in community structure, diversity and abundance of reef-associated organisms (Weil, 2004).

Figure 7. Common coral diseases in the Caribbean. (A) Diploria strigosa with black band disease, (B) Dichocoenia stockesii with white plague, (C) Acropora cervicornis with white band and (D) Montastraea faveolata with yellow blotch syndrome. Source: www.reefresilience.org/coral-reefs/stressors/coral-disease/disease-impacts/
Figure 7: No wonder their as white as a sheet…and yellow…and black!                    (A)  black band disease, (B) white plague, (C) white band and (D) yellow blotch syndrome. Source: www.reefresilience.org

 

 

Bad news, the Worlds Resource Institute reports 10% of coral reefs are permanently damaged; even worse, global warming trends suggest SST will reach that pesky 1℃ resulting in increased bleaching frequency and intensity (Burke et al., 2011). If we continue business-as-usual, 90% of coral reefs will be in danger by 2030 and all by 2050 (Burke et al., 2011).

 

 

 

 

 

 

 

References

Baker, A.C., Glynn,P.W. & 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(4), pp. 435-471.

Bellard, C., Bertelmeier, C., Leadley, P., Thuiller, W. & Courchamp, F., 2012. Impacts of climate change on the future of biodiversity. Ecology Letters, 15(4), pp. 365-377.

Burke, L., Reytar, K., Spalding, M. & Perry, A., 2011. Reefs at Risk Revisited , s.l.: Worlds Resource Institute .

Frieler, K., Meinshausen, M., Golly, A., Mengel, M., Lebek, K., Donner, S. & Hoegh-Guldberg, O., 2013. Limiting global warming to 2 ◦C is unlikely to save. Nature Climate Change, Volume 3, pp. 165-170.

IPCC, 2007. Climate Change 2007: Synthesis Report, Valencia: IPCC.

Jackson, J., Donovon, M., Cramer, K. & Lam, V., 2014. Status and Trends of Caribean Coral Reefs: 1970-2012, Washington, D.C. : Global Coral Reef Monitoring Network.

Jones, G. P., McCormick, M. I., Srinivasan, M. & Eagle, J. V., 2004. Coral decline threatens fish biodiversity in marine reserves. PNAS, 101(21), pp. 8251-8253.

National Oceanic and Atmospheric Administration (NOAA), 2016. Global Analysis- Annual 2016. [Online]
Available at: https://www.ncdc.noaa.gov/sotc/global/201613

National Oceanic and Atmospheric Administration (NOAA), 2017. Coral Reef Watch. [Online]
Available at: https://coralreefwatch.noaa.gov/satellite/analyses_guidance/global_coral_bleaching_2014-17_status.php
[Accessed 20 03 2017].

Weil, E., 2004. Coral reef diseases in the wider Caribbean. In Coral health and disease (pp. 35-68). Springer Berlin Heidelberg.

[Word Count excluding title, captions and references: 500]