There is a huge amount of information available about coral reef health and in particular the mass coral bleaching events that have occurred over the past two years. Two of my previous posts are linked below, but if you scroll to the bottom of the page there are a range of other articles, reports and websites regarding coral bleaching that you might find useful.
Mass coral bleaching events
Coral bleaching - reef resilience
Students should define the following key terms:
- natural selection
Answer the questions below. Conduct internet research to find articles and reports which support your answers.
Coral bleaching - GBRMPA
Coral bleaching and the Great Barrier Reef - ARC CoE
Coral bleaching: Extreme heat pushes parts of the Great Barrier Reef beyond recovery - ABC
Coral bleaching events - AIMS
Great Barrier Reef: a "hopping hotspot" - Australian Geographic
The changes in temperature and associated bleaching are resulting in a different mix of species on the reef. This will impact reefs in the long term.
Loss of species
Fish, whales, dolphins, sharks, rays and the many other organisms found in reefs rely on the complexity of the ecosystem for survival. Some fish rely on the colour of the corals for camoflauge and the structure of the coral for hiding. Many organisms are unable to carry out normal functions and processes as a result of the increased ocean acidification associated with climate change. Shellfish are less able to create their shells due to increased pH. Slow growing corals will take 100-200 years to recover, meaning that the reef will not exist in the form that we have known it in the past.
Dispersal of spawn
Ocean warming impacts on the dispersal or coral spawn (eggs). Increased ocean temperatures result in a decline in the dispersal distance of coral spawn from the origin (parent coral) to the destination site. This change in dispersal patterns can impact on species' distribution, abundance or corals in particular areas and genetic diversity across reefs. Changes to dispersal patterns can also impact on the connectivity (interconnections) between different areas of the reef by limiting the areas of reef that particular coral species are located.
Poleward shift of species
Ocean warming can also result in a poleward shift of species from tropical zones to more temperate zones. Warmer waters are found further from the tropics and species are able to take advantage by increasing their range.
In Western Australia, a species of wrasse - cheorodon rebuscens has started to shift its range with displacement of recruits south of its usual habitat. There is evidence of high recruitment at the temperate edge and no recruitment at the tropical edge. The range shift provides limited expansion opportunities, reducing resilience of the species.
Irukandji are migrating further south on the Great Barrier Reef as a result of warmer waters and are also having longer seasons in other areas. There have been anecdotal reports of increases in reports of stinging and hospitalisations on islands within the Great Barrier Reef (e.g Fitzroy Island) and snorkellers are being strongly advised to wear stinger suits outside of usual peak Irukandji seasons. Irukandji and associated stingings have also been reported on western side of the southern tip of Frazer Island where they haven't previously been found.
Following bleaching events or even natural disasters, corals can become overgrown with algae, making it difficult for coral recruits to settle and grow. The mix species on a reef can impact on how resilient that particular reefs is. For example in Moorea in French Polynesia experienced high coral mortality in the 1980s. Recovery of the reef was enabled in part as a result of grazing fish such as parrot fish removing some of the algae in the process of eating corals. In this way the biodiversity of the reef contributed to high levels of resilience on the reef in comparison to some other reefs globally. The scale of the bleaching on GBR make it unlikely that these types of natural processes will have much of an impact on recovery.
Below: A parrot fish on the outer reef, 2015.
The title for this blogpost came from a comment Dermot O'Gorman made in his presentation at the Eco Expo last weekend (you can read my post Living in Harmony with Nature for more information). As I listened to his presentation I was typing away on my iPad and yes I did tweet. I was a little taken aback by the comment because I have used twitter to connect with environmental groups, researchers, other geography teachers and whole range of like-minded people. As a teacher, Twitter has given me access to current research in education, geography and science, newspaper articles from around the world and discussions on a whole range of issues. It came as a bit of shock to think that maybe sharing all this information wasn't actually achieving anything beyond my own classroom.
Last week as the new Federal government axed the Climate Commission and moved forward with plans to cut the carbon tax, I saw a plethora of disheartened people conversing, but it seemed that everyone was feeling a little helpless and depressed. Links to a few petitions regarding the axing of the Climate Commission were making the rounds, but they were interspersed with a number of other petitions about new government policies (NBN, cuts to universities, etc). O'Gorman's comment came back to me. Is all this discussion actually going to get anywhere?
At midnight, a new twitter and facebook account opened - the Climate Council. People were invited to sign up and donate money to get the Climate Council off the ground. Made up of many of the same people as the Climate Commission, this group are set to continue the work of the Climate Commission without using federal government money. So many people signed up and tried to donate that the twitter account got suspended several times and the facebook account kept requiring captcha requests to ensure that the popularity and spread of the site was legitimate. In the first 13 hours they had raised $160,000 to get the council up and running, and by the end of the day they had reached over $247,000. This is a great example of how the virtual world can create real change in the real world.
Scientists say climate cuts leave public in the dark.
Support for Climate Council takes off.
Deputy Principal at a Sydney high school. Coordinating author of the new Geoactive book series.
7-10 Geography pages have been retired due to the introduction of the new syllabus. The above links relate to current NSW syllabuses. All Commerce and Legal Studies resources have been moved onto this main site (search Commerce or Legal Studies below).