The University of Southampton

Tag: species loss

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.


Roads Reduce Role of Rainforests

Posted on by Anonymous

Rainforests are considered ‘the finest celebration of nature ever known on the planet’ yet increasing pressure to develop new roads for economic growth is their biggest threat.

Tropical rainforests cover 2-7% of Earth. They support 170,000 plant species. Their small area but tremendous biodiversity makes them global hotspots for conservation funds.

High levels of rainfall and constantly high temperatures creates a unique habitat. Many trees packed closely together creates a closed canopy. As a result, the rainforest is dark and humid. There is lower light, wind and temperatures as a result that species need to be specially adapted to in order to thrive (Laurance et al. 2009).

New developments threaten this structure. Species can either respond and adapt to new conditions or face the risk of extinction.

Rainforests are especially vulnerable to economic pressures. Roughly 2.5 million hectares (25,000km2) of the Brazilian Amazon are lost every year through deforestation. Economic growth is often the main driver for habitat loss. If the current rates continue, within 50 years, global rainforests are likely to be lost forever.

Many activities lead to deforestation but roads are seen as especially detrimental (Figure 1). Opportunities for logging, oil and mining often drive the development of new roads (Goosem 2007). Previously untouched areas are now accessible via roads and are now vulnerable to widespread biodiversity loss (Brudvig et al. 2015; Haddad et al. 2015).

Figure 1. New roads create barriers between previously connected species. Barriers for reproduction and pollination ultimately lead to species loss.
Figure 1. New roads create barriers between previously connected species. Barriers for reproduction and pollination ultimately lead to species loss.

The issue is not only minor access roads but large highways built for an increasingly urban world. The Trans-Amazonian Highway in Brazil is 4000km. This only makes it the third longest highway in Brazil (Figure 2).

Destruction of the rainforest is therefore a primary cause of plant biodiversity loss. Roads will change rainforest habitats from large and pristine to small and isolated. New edges are created alongside roads. Species are impacted more than this than widespread deforestation. This process of habitat fragmentation creates smaller, isolated populations and plant species are lost (Linert 2004; Gossem et al. 2011; Weiner et al. 2014).

Figure 2. Trans-Amazonian Highway is among one of many road developments through tropical rainforests that result in widespread deforestation and loss of important plant species that play vital roles in regulating carbon dioxide levels on Earth.
Figure 2. Trans-Amazonian Highway is among one of many road developments through tropical rainforests that result in widespread deforestation and loss of important plant species that play vital roles in regulating carbon dioxide levels on Earth.

Overall, trees lost from the rainforest allows light to reach the ground that was not able to before. Shade preferring species are no longer the best suited. Those plants that thrive on more light become more successful (Laurance et al. 2009). Species that were one dominant no longer are.

These changes to the surrounding environment impact important interacting species. Smaller patches with different conditions attract fewer plant species and therefore fewer pollinators. Pollinating species are likely to decline as a result, threatening their own survival and that of the plants (Aguilar et al. 2006).

If reproductive output declines, the number of species surviving to continue the population declines. The negative cycle continues until a whole species is extinct. Community structure is altered and important interactions are lost.

Each plant species, rare or common, plays an important role in regulating carbon, purifying water and stabilising soil qualities. Loss of species variety creates areas that are extremely similar. Soon, rainforests will lose their functional role and contribute less to the global system.

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REFERENCES

Aguilar, R., Ashworth, L., Galetto, L. & Aizen, M. A. (2006) Plant reproductive susceptibility to habitat fragmentation: review and synthesis through a meta-analysis. Ecology Letters, 9, 968-980.

Brudvig, L. A., Damschen, E. I., Haddad, N. M., Levey, D. J. & Tewksbury, J. J. (2015) The influence of habitat fragmentation on multiple plant-animal interactions and plant reproduction. Ecology, 96, 2669-2678.

Cunningham, S. A. (2000) Effects of habitat fragmentation on the reproductive ecology of four plant species in mallee woodland. Conservation Biology, 14, 758-768.

Goosem, M. (2007) Fragmentation impacts caused by roads through rainforests. Current Science, 93, 1587-1595.

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., Cook, W. M., Damschen, E. I., Ewers, R. M., Foster, B. L., Jenkins, C. N., King, A. J., Laurance, W. F., Levey, D. J., Margules, C. R., Melbourne, B. A., Nicholls, A. O., Orrock, J. L., Song, D. A. & Townshend, J. R. (2015) Habitat fragmentation and its lasting impact on Earth’s ecosystems. Sci. Adv.

Laurance, W. F., Goosem, M. & Laurance, S. G. W. (2009) Impacts of roads and linear clearings on tropical forests. TREE, 1149, 1-11.

Lienert, J. (2004) Habitat fragmentation effects on fitness of plant populations – a review. Journal for Nature Conservation, 12, 53-72.

Weiner, C. N., Werner, M., Linsenmair, K. E. & Bluthgen, N. (2014) Land-use impacts on plant-pollinator networks: interaction strength and specialisation predict pollinator declines. Ecology, 95, 466-474.