Today we want to talk to you about a matter of life and death: the state of health of the Great Barrier Reef.
Recently we have been a little uneasy with some comments from followers that the Reef looks in pretty good nick. In an attempt to focus on the riches of the Reef and highlight what is at stake, we have shown and written about more of the positives than the negatives. We worry that based on some of our posts you might think the Reef is just fine. This is not the case. After spending several months at the Great Barrier Reef this year, and on our fourth year of reef exploration, it is time to reflect on what we have seen – warts and all – as you know us for.
So how do we really see the state of the Reef? B L E A K
Overall, we have noticed a marked deterioration. We see less colour in the corals, less density, more algae, less fish variety and quantity. We have also witnessed extremes in reef health: significant destruction along the inner and fringing reefs, vigorous growth on the outer reefs. Of course with any coral destruction you also lose habitat and food source for the fish populations that dwell in those reefs.
Four elements are damaging to the reef:
- Increased ocean temperature creating bleaching or heat stress.
- Coastal runoff which increases turbidity, adds nitrogen in the water, both resulting in algal growth that suffocates the coral.
- Increasingly violent and frequent storms that uproot corals and smash reef platforms.
- Crown of Thorn Starfish infestations that devour corals.
Big differences between fringing, inner and outer reefs
We have observed a significant difference between the inner and outer reefs. The satellite image below shows a section of the Great Barrier Reef. Within the dark blue stretch you can see two distinct lines of reefs which run along its entire length, an inner line, closest to the coast, and an outer line, furthest offshore on the edge of the Continental Shelf. There is also a string of continental islands between the mainland and the reef.
Fringing and Inner Reefs
The fringing reefs edging the continental islands located 8 to 10nm off the coast are in the worst state. This includes areas like the Keppels, the Whitsundays, the islands off Townsville and Cairns. The water is turbid with increased sediment, pollutants and contaminants. You dangle your feet at the back of your boat and they disappear into a milky opaque water with poor visibility. With little light penetrating under the surface, hardly any coral is left and there is low fish population.
The whole line of reefs running about 30nm from the Queensland coast is also very damaged. Here is what many of the inner reefs look like:
When corals are stressed by changes in conditions such as temperature, light, or nutrients, they expel the symbiotic algae living in their tissues, causing them to turn completely white. We have not seen the totally bleached white coral expanses that are often shown on TV. We have seen patches of this, but typically what follows after bleaching is algal growth… and that we have seen… a lot!
Bleached corals are weaker and more susceptible to a microbial takeover fuelled by algae. Once fleshy algae gain foothold in a reef, it encourages the growth of disease-causing micro-organisms that can kill coral. It is not uncommon for lagoons to heat up too much in summer and consequently we are seeing less and less live corals inside these shallow inlets on the inner reefs.
Why is it so bad at both the fringing and inner reefs? Because they are affected by multiple stressors, the big one being agricultural runoff. In addition, some of these reefs have also suffered the effect of storms a few years ago and most of them have been affected by marine heat waves repeatedly over the past five years. With multiple devastating assaults, can they survive and recover? We worry they won’t.
A little further offshore, things are less dire, but not good. Some reefs positioned a bit more centrally on the GBR are in reasonably good condition, however it is dependent on where you go and where you look. You will see live coral colonies, often on the more exposed slopes rather than in the lee of the reef platform, but there are areas of dead coral covered in algae. Generally 40% cover is what you can expect.
The healthiest reefs we have seen are the ones on the very outer edge of the Great Barrier Reef where marine life is thriving thanks to their position along the Continental Shelf with its upwelling of clean, cool and nutrient rich ocean waters.
The offshore reefs in the central and northern region (offshore of Mackay, Townsville and Cairns) have been damaged by large scale coral bleaching events but they are fighting back. The Reef is incredibly resilient and despite the onslaughts it is recovering in places far from the coast, 50 to 90nm offshore, where there are areas thriving with life and vigorous coral growth again. It gives us some hope, as long as another bleaching event does not cook the new growth this summer.
Crown of Thorn Starfish – it can hit anywhere
As if storms and rising temperatures aren’t enough, there is the impact of the Crown of Thorns Starfish (COTS). These can invade an area and obliterate the corals at lightening speed. They feed on branching and table corals such as Acropora species rather than more rounded corals with less exposed surface area, such as Porites. Like other starfish, they exude their stomach and start the process of digestion outside their body. They settle on a piece of hard coral, release chemicals which attract additional COTS to healthy reef sections. They then begin their destructive feeding frenzies, releasing digestive enzymes onto the reef, and liquefying the coral tissue. You will notice the white coral skeleton – the scar – where they have digested the polyps as they move around and eat their way through an area. The coral skeleton is then rapidly infested with filamentous algae. An older scar will look brown or grey. During a severe outbreak, there can be many crown-of-thorns starfish per square metre, even piling on top of each other. They can eat so much that they can kill most of the living coral in that part of the reef, reducing hard coral cover from the usual 25 – 40% of the reef surface to less than 1%. Such a reef can take 10 years or more to recover its coral cover.
Last year we saw and reported a COTS outbreak at Walker Reef. It got dealt with swiftly. We returned to that reef this year and it is showing some signs of recovery, but very patchy. We are told by marine biologists at the Australian Institute of Marine Science (AIMS) that the Swain Reefs have been badly damaged by COTS. These are the furthest offshore reefs on the GBR, some 150 nm from the coast. We are yet to go there at this stage. The GBR Marine Parks Authority is quick to react to reports of outbreaks and send teams to cull the COTS. We have seen Crown of Thorns but not at outbreak level anywhere again and we have seen the scars they leave behind on most reefs.
Thank God for Green Zones
One thing is encouraging: the effect of the Marine National Park Green Protection zones which forbid fishing or take of any kind and in so doing limit the activities of people using and abusing those fragile places. Reefs in green zones are in noticeably better condition with many more fish. But they represent only 33% of the Great Barrier Reef Marine Park. We need more of these protected areas to help preserve and restore habitat. The Marine Park people are patrolling these reefs by air and sea and severe fines are imposed on those breaking the rules. We have little pity for those getting caught.
The Reef is a sensational and delicate ecosystem. We have shown this in our series of Outer Reef posts. We have been incredibly lucky to spend so much time exploring and witnessing what is there, good and bad.
But there is no denying that the Great Barrier Reef is being ravaged by climate change. Should it be listed as an endangered world heritage site? Yes, because it is, and we are running out of time to halt the devastation. How long have we got? We don’t know, marine biologists we met on our journey don’t know either. We fear we are talking a few years rather than several decades.
What we do know is this… If we stay on the current destructive trajectory, burning fossil fuels, letting agricultural run off flow carelessly into our rivers and inshore waters, if we keep over populating and overfishing, if we keep showing an insatiable desire for stuff, if we keep getting rid of waste recklessly, we will surely kill what is left of the Reef, and not in the distant future, but very, very soon.
It is sad to see that while everyone has been distracted with the global pandemic and focused on saving people, the real issue of protecting, nurturing and safeguarding the environment and the very ecosystems that keep us and every living thing alive have been neglected.
When will our local and global priorities change? When will we shift our focus to the real crisis of our time?
We need climate action now, but our Australian politicians don’t really get it. Rather than taking energetic and urgent action, Australia’s so-called Plan lazily falls back on projections that emissions will fall by up to 35% by 2030, “exceeding” the federal target of 26 to 28% that was set some 6 years ago by just “momentum”. This is half of what we need to do! While some countries in the rest of the world try, with targets and properly costed and mandated strategies, we have no plan for 2030, having been dragged kicking and screaming to reach even a woolly, irrelevant 2050 net-zero promise. Our leaders worry about their re-election rather than the climate crisis with its dyeing reefs, rising seas, catastrophic bushfires, cyclones and floods. Our prime minister is embarrassing, lacks leadership, vision and diplomacy, and certainly doesn’t represent us. We can’t wait for the next federal election… to show our current leaders what we think of their Plan and vote them out! We hope many other Australians do likewise.
Only with bold, ambitious 2030 targets, and new, concrete policies will we reverse this global emergency. Let’s hope the COP26 Summit achieves the shake up that is so desperately needed.
Rant over! We look forward to your comments.