Life on the Rocks: all may not be lost for our coral reefs

Reading Julie Berwald's Life on the Rocks, it's a little easier to get some perspective on the plight of our coral reefs. It's well-known that coral reefs throughout the world are in trouble, and that our warming oceans are bleaching and killing them, although it's not easy to get a handle on just how bad things are. Added to that is: the threat to the reefs from agricultural run-off, oil spills and other chemical pollutants; direct destruction from shipping accidents, over-enthusiastic fishermen and clumsy tourists; increasingly frequently and intense hurricanes, typhoons and cyclones; suffocation by a plume of floating sunscreen and plastic; and a whole litany of diseases and viruses that have hit the reefs in recent decades. It's a tough life being a coral.

I'm not going to regurgitate the depressing statistics here - suffice to say, about half of the world's 28 million hectares of coral reefs are damaged or dead, most of that over the last 30 or 40 years - and, interestingly, that is not the point of Ms. Berwald's book (it has been well enough documented elsewhere). Life on the Rocks has a more upbeat message: all is not lost.

For example, Ms. Berwald looks at various schemes to protect or shade corals. She introduces us to a whole sub-culture of coral farmers, collectors and artisanal aquarium traders. She describes, too, the relatively well-known project initiated by the Mars chocolate company to improve the reefs around their cacao plantations in Sulawesi, Indonesia, using networks of steel rebar with coral fragments tied on with zip ties. The Mars initiative in particular has been extremely successful, becoming one of the largest reef restoration projects in the world, and has generated several copy-cat projects in other parts of the world.

But, more interesting to me, she explains how it has become apparent (thanks to extensive experimental work by coral scientists like Dave Vaughan in Florida) that it is actually much easier than was once thought to rebuild coral reefs, through an increasingly effective toolbox of techniques like fragmentation, micro-fragmentation, fusion and reskinning, and how coral has surprised scientists with the speed with which it can regenerate under certain conditions and with certain kinds of help.

Also, it turns out that, when a reef bleaches, or even dies off completely, a few individual corals DON'T die. It's not entirely clear how or why, but the survivors do have certain gene expressions in common. And it also turns out that corals in general, and those with certain genes in particular, are much more adaptable to rising temperatures, acidification and pollution than was once thought, and much more resilient in general. Warm-water corals bred with other warm-water corals are much more resistant to rising temperatures than cool-water temperatures. Some algae symbionts allow corals to become more heat tolerant than others. There are a lot of factors to play with, and the good news is that scientists are finally getting to grips with which factors (characteristics/genes/symbionts/etc) matter most.

It seems we have come a long way since those old Jacques Cousteau videos, important though they were in their own way. Life on the Rocks is a welcome antidote to the doom-and-gloom environmental reporting we so often see. It celebrates little victories in a fight against almost impossible odds, and lauds the brave amd indefatigable scientists who chose not to accept defeat.

In between these descriptions of some of the successes in coral restoration, Ms. Berwald also explains about the fascinating life-cycle of coral, and intersperses factoids like: 

• many corals are sequential hermaphrodites, changing from male to female or vice versa, and some release both egg and sperm packets, but separately so that they don't fertilize themselves; 
• individual corals of the same species spontaneously spawn at the same time each year, despite being separated by many kilometers; 
• some corals are 200 times as venomous as a rattlesnake, and 6,000 times as venomous as a black widow spider; 
• coral polyps have a mutualistic relationship with different species of algae that live actually within their cells, with the algae getting a protected place to live, and the coral getting the food and oxygen it needs to live (as well as those dazzling colours); 
• corals were around at the time of the dinosaurs, and remain almost unchanged; 
• a single polyp is not in itself an animal, even though it looks separate - the animal is the coral as a whole, which is made up of thousands of little polyps;
• corals can produce their own chemical "sunscreen" in day-glo fluorescent colours, with which they try to protect themselves against warming waters and sun-bleaching.

All in all, a book well worth reading, and not half as depressing as you might have thought.