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Tag: great barrier reef

Why those holiday snaps may never look the same again….

Posted on by Lauren Scrace

From Sunday night Attenborough documentaries, to gap year photos from people you haven’t seen for years, we’re becoming increasingly informed about the world around us, enticing us to explore.

The Great Barrier Reef stretching the Queensland coastline is such a vast natural spectacle it can be seen from space. This complex ecosystem is home to over 450 types of coral and provides a habitat for marine creatures ranging from tropical fish to turtles (1), making it a popular holiday destination but for how much longer?

Lizard Island, Luxury Lodges of Australia, Queensland
Unbleached Coral reef community. Queensland (2)

This beautiful system is under threat from rising sea temperatures, putting stress upon the corals causing them to release the algae from their tissues leaving only ghostly white calcium skeletons remaining. Both the coral and the algae rely on their partnership for energy and safety.

These ‘bleached’ corals are unsustainable and will perish within weeks if the sea temperature fails to return to within tolerable ranges. Due to the certainty of rising ocean temperatures, restoration success is unlikely and the devastation likely to continue. (1)

Once a year the reef engages in mass reproduction, triggered by temperature and the lunar cycle, this supports continued reef biodiversity as well as providing an ample source of food for reef dwellers. A shift in the temperature cues for reproduction will have severe impacts on community biodiversity as compared to natural incidents global shifts cause a greater long term impact, reducing the possibility of recovery (3).

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Coral bleaching event. Picture credit- The Ocean Agency / XL Catlin Seaview Survey / Richard Vevers  (4)

Environmental change that impacts the structure of the corals will also affect their functional ability within the community. (5) Corals provide shelter for many marine species, allow for protected migration and increased genetic flow through coral corridors.  This change alter the community structure and exasperate the global mass extinction we are currently experiencing.

So what is actually happening?

Global activities are impacting the future of this system dramatically, through climate change and our ever-increasing carbon footprint.

Corals extract calcium carbonate (the substance that forms eggshells) from the surrounding sea water to build the reef, using energy utilized from the algae within their structures. Each species builds differently to give beautifully diverse reefs, supporting creatures from zooplankton to green turtles.

Increasing atmospheric CO2, is absorbed by the oceans where its combined with seawater to produce an acid, leading to ocean acidification. This reduces the concentration of carbonate ions available for use by the corals to build their structures. (6)

These global changes aren’t the only driver of community shifts. On a local scale, flooding in Queensland has caused sediment and pesticide run off into the oceans. This increased nutrient input is devastating to a system reliant on diversity (7,8),  where some species are more susceptible to change than others, causing a decline in both population density and biodiversity.

So our holiday snaps might never look the same again… To mitigate this change we need to alter our way of life, just travelling to see them impacts their survival! But keep snapping and keep people talking, its the only way we are going to make change!

 

5.8 tonnes of CO2 is released per person during a flight from London to Darwin Australia!! 
Flight # Details: Tonnes CO2
1 Return From London Gatwick to Darwin Australia 1 passenger 5.8

 

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References

  1. Australia’s Coral Reefs under Threat from Climate Change by Lesley Hughes, Will Steffen and Martin Rice (Climate Council of Australia).
  2. Great Barrier Reef | Australia’s Great Natural Wonder”. Great Barrier Reef. (2017). 21 Mar. 2017.
  3. Nyström, M., Folke, C., & Moberg, F. (2000). Coral reef disturbance and resilience in a human-dominated environment.Trends in Ecology & Evolution, 15(10), 413-417.
  4. The Ocean Agency. 2016. THE 3RD GLOBAL CORAL BLEACHING EVENT – 2014/2017. Available at: http://www.globalcoralbleaching.org/#essential-facts. [Accessed 21 March 2017].
  5. Richmond, R. H. (1993). Coral reefs: present problems and future concerns resulting from anthropogenic disturbance.American Zoologist, 33(6), 524-536.
  6. Hoegh-Guldberg, O., Mumby, P. J., Hooten, A. J., Steneck, R. S., Greenfield, P., Gomez, E., & Knowlton, N. (2007). Coral reefs under rapid climate change and ocean acidification.science, 318(5857), 1737-1742.
  7. Mongin, M., Baird, M. E., Tilbrook, B., Matear, R. J., Lenton, A., Herzfeld, M., & Duarte, C. M. (2016). The exposure of the Great Barrier Reef to ocean acidification.Nature communications, 7.
  8. Dubinsky, Z. V. Y., & Stambler, N. (1996). Marine pollution and coral reefs.Global change biology, 2(6), 511-526.


The Great Barrier Reef – Not so Great Anymore

Posted on by Edward Simmons

The great barrier reef is a place that the vast majority of people have heard of, perhaps due to its incredible natural beauty, or maybe due

Figure 1: An image of the great barrier reef we’re all familiar with; full of colour and life. Source: Cruiseexperts.com
Figure 1: An image of the great barrier reef we’re all familiar with; full of colour and life.
Source: Cruiseexperts.com

to the large host of species that it supports. Around 150 soft corals, 411 hard corals, 1625 bony fish, and about 1300 crustacean species call the great barrier reef their home, to name a few (Great barrier reef marine park authority, 2014). However, climate change is impacting the corals that make up the structure of the reef, with an estimated yearly loss of around 3,168km2 per year being the calculated loss between 1997 and 2003 alone (Bruno and Selig, 2007).

 

 

 

 

What are the Impacts of Climate Change?

 

Figure 2: Sea surface temperature anomalies for the Coral Sea, 1900-2013, using 1961-1990 average as a baseline. Source: Great barrier reef marine park authority, 2014
Figure 2: Sea surface temperature anomalies for the Coral Sea, 1900-2013, using 1961-1990 average as a baseline. Source: Great barrier reef marine park authority, 2014

Climate change has caused the sea surface temperatures to rise in recent years, as shown by figure 2 for the Coral Sea. In fact, the past 15 years has shown the hottest temperature averages all together, and this has many impacts on the animals and plants that live within the sea. This temperature rise leads to a phenomenon called coral bleaching. This is where corals lose their symbiotic algae, which live within the coral and provide it energy, which can lead to the coral’s death if the bleaching is prolonged or severe. The effects of this are easily seen, as the corals lose their colour, leaving just the white of the calcium skeleton (Brown, 1997).

As the temperature of the water increases, so does its ability to absorb CO2, leading to ocean acidification. The current level of atmospheric CO2 has been measured at 406.42 ppm, (NOAA, 2017), which is more than 100ppm above the maximum values seen over the last 740,000 years (Hoegh-Guldberg et al. 2007). 25% of the CO2 created by humans goes into the sea, leading to significant acidification. As the water turns more acidic, corals are unable to create their calcium skeletons as well, decreasing the rate at which they grow. The growth of corals has in fact decreased by 13.3% since 1990 (De’ath et al. 2009).

Climate change may lead to indirect damages to coral reefs too, with it leading to an increase in both the number and the intensity of storms, including hurricanes, in some regions (Hughes et al. 2003). This damages the corals, and the increase in frequency of the storms gives the reef less time to recover, killing some corals completely.

 

 

 

More than just the corals

Figure 3: Drained of colour, a contrast between a reef before and after bleaching. Source: dw.com
Figure 3: Drained of colour, a contrast between a reef before and after bleaching. Source: dw.com

The health of the corals also effect the many animals that inhabit the reef. The worst affected are the fish that require live corals as their homes, but fish that don’t depend on live coral are impacted too, as they are still dependent on the complexity of structure that the live coral bring (Pratchett et al. 2008).

With climate change growing more intense year by year, up to 60% reefs may be lost by 2030, and with them all the life which calls the reef home (Hughes et al, 2003).  So, while it certainly remains a barrier reef, perhaps it’s not so great anymore…

 

 

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References

 

  • Brown B.E. 1997. ‘Coral bleaching: causes and consequences’ Coral reefs, 16, pp. 129-138
  • Bruno J.F. and Selig E.R. 2007. ‘Regional Decline of Coral Cover in the Indo-Pacific: Timing, Extent, and Subregional Comparisons’ PLoS one 2(8), e711
  • De’ath G., Lough J.M., Fabricus K.E. 2009. ‘Declining Coral Calcification on the Great Barrier Reef’ Science, 323, pp. 116-119
  • Great Barrier Reef Marine Park Authority 2014, Great Barrier Reef Outlook Report 2014, GBRMPA, Townsville.
  • Hoegh-Guldberg O. et al. 2007. ‘Coral Reefs Under Rapid Climate Change and Ocean Acidification’ Science, 318, pp. 1737-1742
  • Hughes T.P. et al. 2003. ‘Climate Change, Human Impacts, and the Resilience of Coral Reefs’ Science, 301, pp. 929-933
  • National Oceanic and Atmospheric Administration (NOAA), 2017. Trends in Atmospheric Carbon Dioxide. [Online] Available at: https://www.esrl.noaa.gov/gmd/ccgg/trends/index.html [Accessed: 21/03/2017]
  • Pratchett M.S. et al. 2008. ‘Effects of climate-induced coral bleaching on coral-reed fishes – ecological and economic consequences. Oceanography and marine biology: an annual review, 46, pp. 251-296


RIP Great Barrier Reef: a Reef In Peril?

Posted on by Claire Murray

The threat of climate change for coral reef ecosystems across the world

By Claire Murray, University of Southampton student

 

the_sun
Losing Nemo? Are we seeing the demise of the Great Barrier Reef? Source: The Sun, 2016

Coral reefs are unique, awe-inspiring ecosystems; distinctively bright, bursting with biodiversity. However, they are already facing impacts of climate change. Headlines last year claimed the death of the most famous coral reef system on earth – the Great Barrier Reef. Whilst the story was greatly exaggerated, the possibility of the threat is all too real.

 

 

 

 

whitecoral
Good greef! Bleached coral, a contrast with the vibrant reef. Source: The Guardian, 2017

The importance of coral

Coral is a living organism, with algae it’s partnering, symbiotic component. Algae and coral are mutually dependent on each other for survival; providing food and a habitat respectively. However, coral bleaching is the loss of the symbiotic algae, occurring due to intolerance to changing environmental conditions such as increased sea temperatures. This is visually evident as a loss of pigmentation; replacing vibrant colours with the white colour of the coral’s calcium structure (Antonelli, et al., 2013). Increasing sea temperatures are a certain consequence of climate change, meaning that more coral bleaching could occur as temperatures increase in the near future (Antonelli, et al., 2013).

 

vibrantcoral
A vibrant coral reef ecosystem, without bleaching. Source: The Sun, 2016

What’s the catch?

Coral reefs provide important local ecosystem services, including coastal protection and fishery support (Hicks & Cinner, 2014). Corals are the main habitat-forming organism in the reef ecosystem – centrally important for biological and physical structure (Coker, et al., 2014). Various species are supported within the ecosystem, making reefs biodiversity hotspots (Hicks & Cinner, 2014). However, rising global sea temperatures are an environmental driver of the change being seen in ecosystems; threatening the benefits the ecosystem brings.

Threats to coral reefs are two-fold: global climate change pressures, and local anthropogenic pressures (Mongin, et al., 2016). Local stressors include pollution, sedimentation and overfishing (Ateweberhan, et al., 2013). Coral reefs are highly sensitive to the global risks of ocean acidification and warming (Ateweberhan, et al., 2013; Wolff, et al., 2015; Van Hooidonk, et al., 2014). The loss of the physical habitat ultimately threatens the abundance of marine life that depends on coral for its survival, reducing the resilience of the ecosystem as a whole.

 

acropora
Acropora coral, found in the Caribbean. Source: Pinterest, 2017

All bad news?

There is inequity of climate change impacts across coral reefs – for example, the Caribbean is likely to experience only relatively low levels of stress (Wolff, et al., 2015). The rates of environmental change also varies at different latitudes, meaning impacts will be staggered throughout the ecosystems on a global scale (Van Hooidonk, et al., 2014).

Despite the obvious negatives experience by the majority of coral reefs, it’s not bad news everywhere. Acropora corals seen on the northern Gulf of Mexico and on the Florida peninsula are extending their range – resulting in new, ‘novel’ ecosystems (Graham, et al., 2014). The emergence of new communities demonstrates the changing dynamics of the ecosystem.

The diverse environmental changes being seen globally are certainly going to impact coral reef ecosystems, and predominantly in a negative way. However some positives are likely; so not all hope is lost. But in the meantime, it might be worth visiting the Great Barrier Reef before it’s too late…

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References

Antonelli, P. L., Rutz, S. F., Sammarco, P. W. & Strychar, K. B., 2013. A coral bleaching model. Nonlinear Analysis: Real World Applications, Volume 16, pp. 65-73.

Ateweberhan, M. et al., 2013. Climate change impacts on coral reefs: Synergies with local effects,. Marine Pollution Bulletin, 74(2), pp. 526-539.

Coker, D. J., Wilson, S. K. & Pratchett, M. S., 2014. Importance of live coral habitat for reef fishes. Reviews in Fish Biology and Fisheries, 24(1), pp. 89-126.

Graham, N. A. J., Cinner, J. E., Norstrom, A. V. & Nystrom, M., 2014. Coral reefs as novel ecosystems: embracing new futures. Current Opinion in Environmental Sustainability, Volume 7, pp. 9-14.

Mongin, M. et al., 2016. The exposure of the Great Barrier Reef to ocean acidification. Nature communications, 7(10732), pp. 1-8.

Van Hooidonk, R., Maynard, J. A., Mazello, D. & Planes, S., 2014. Opposite latitudinal gradients in projected ocean acidification and bleaching impacts on coral reefs. Global Change Biology, 20(1), pp. 103-112.

Wolff, N. H. et al., 2015. Global inequities between polluters and the polluted: climate change impacts on coral reefs. Global Change Biology, 21(11), pp. 3982-3994.