Living as part of a blue planet

Coral reefs form the most biodiverse ecosystems in the world and as the most critically and irreversibly endangered, they must take centre stage when we consider marine conservation. As an example, one single reef from the Coral Triangle in the Indo-Pacific can be home to as many as over 1500 species of fish and 600 species of corals – all relying on each other in a close symbiosis! Unfortunately, due to multiple human effects, reefs around the world are being degraded and lost forever. One of the major impacts comes from the warming of ocean waters around the tropics, which causes a process known as coral bleaching. A permanent increase of as little as 1ºC above the normal average sea temperature can lead to the death of a coral reef and as shown by the photo on the right the noticeable difference is truly heartbreaking! We will return to explore the effects of coral bleaching in sections further down, but it’s important to remember that its impact is worsened by other human activities, so the actions we take need to address them collectively!

Most of the problems the oceans face, such as coral bleaching and pollution, are caused by the small actions that we might not think make a difference. Major threats stem from our daily use of nonrecyclable plastics, consumption of fish from fisheries that damage the environment, and the energy we use around the house (like leaving lights or other electronic appliances on when not in use) – all of these are very easy to reduce!

There are many things you can do daily to have a positive impact. From recycling plastic to raising awareness for conservation campaigns, all of these solutions help us to protect the oceans and the livelihoods they sustain for the future!

To better understand the actions you can take and how they help, try to match each of the problems shown on the poster (on the right) with a relevant solution! The answers are shown as inverted at the bottom.

Among the numerous threats to ocean biodiversity, coral bleaching is projected to cause the biggest disturbance to the reef communities supporting fish stocks and to the hundreds of millions of people that rely on them. The bleaching process all comes down to the symbiotic relationship between the polyps forming the coral structures and tiny zooxanthellae algae that live inside their cells and provide the polyps with nutrients in exchange for a safe home. When the algae are stressed by changes in ocean temperature, intense sunlight or pollution, they actively leave the coral and break that relationship, so the polyps begin to starve and may die. As the algae have photosynthetic pigments, the colour of the corals disappears together with them and that is how we see bleaching occur. Importantly, if conditions improve the algae can be up-taken by the coral again and some species are more resilient to environmental changes than others, so there is some hope for restoration projects. The colour reference chart, which you can see on the bottom of our coral photos and shown here as used by researchers at the University of Queensland, was originally developed by Siebeck et al. in 2006 and it has been very important for allowing a cheap and reliable method to standardise the surveillance of coral reefs around the world by comparing their colours in each stage of the bleaching process to the relevant hue of the chart. The bleaching shown in the photos has been scaled to represent what a 1ºC increase in temperature would cause for the corals.

Multiple citizen science projects are currently using this methodology, offering an opportunity for the public to get involved.