Guest Post by Willis Eschenbach
I’ve written a few times on the question of one of my favorite hangouts on the planet, underwater tropical coral reefs. Don’t know if you’ve ever been down to one, but they are a fairyland of delights, full of hosts of strange and mysterious creatures. I’ve seen them 
far from the usual haunts of humanoids, where they are generally full of vigor and bursting life.
I’ve also seen them in various stages of ill-health, including the bleaching caused by occasional high temperatures (which a healthy reef recovers from in a few years). In all of my writings on this subject, I’ve said that the health of the reef depends in large part on parrotfish. I’ve proposed that atoll nations declare the parrotfish as their national bird, just to bring attention to the fish that are responsible for the very existence of the atolls themselves.
This is for two reasons. First, parrotfish are herbivores. They graze on the algae that is constantly trying to take over the reef. This keeps the reef clear of algae so that the coral polyps can get the sunlight that they need to survive.
Second, the parrotfish graze by biting off chunks of coral. They crunch these up between specialized bony plates in their throats, digest all of the greenery, and they subsequently excrete nothing but the finest, whitest, softest coral sand … the very sand that makes the romantic tropical beaches. It’s quite funny to see what happens if you disturb a whole school of them—they drop their entire load and disappear in a flash, leaving nothing but a white cloud of sand slowly dropping to the ocean floor, eventually to be swept by the waves up onto the beach.
Unfortunately, although parrotfish are wary during the day, they sleep at night out in the open. As a result, the advent of the waterproof flashlight has led to their local extinction on many reefs.
To bring this story up to the present, over at his excellent NoTricksZone website, Pierre Gosselin points out a press release from the International Union of Concerned Scientists (IUCN) entitled From despair to repair: Dramatic decline of Caribbean corals can be reversed. It discusses a recent report called “Status and Trends of Caribbean Coral Reefs, 1970-2012”, linked to below.
In the press release, they point out that although climate change has been blamed for the decline in Caribbean coral reefs, the major reason for the decline is … drum roll … the loss of the parrotfish and other reef grazers. The press release says:
Climate change has long been thought to be the main culprit in coral degradation. While it does pose a serious threat by making oceans more acidic and causing coral bleaching, the report shows that the loss of parrotfish and sea urchin – the area’s two main grazers – has, in fact, been the key driver of coral decline in the region.
Despite the obligatory nod to climate change, they have finally come to their senses.
Now, the IUCN has been heavily invested in the “climate change” meme, so I find this to be a most welcome sign that perhaps some sanity is returning to the field. Back a decade ago I wrote about role of parrotfish in reef loss, but at that time everyone from the Sierra Club to the IUCN were blaming climate change.
And this is one of the huge problems with blaming everything and its cousin on climate change—when you blame wrongly climate change, you ignore the real problem. For example, the claimed (but illusory) “sinking” of coral atolls was long blamed on sea level rise from climate change.
But all that did is obscure the real danger to coral atolls, which is the decline of the reefs on which they depend for their continued wellbeing. Regarding the Caribbean reefs, the report itself says:
Outbreaks of Acropora and Diadema diseases in the 1970s and early 1980s, overpopulation in the form of too many tourists, and overfishing are the three best predictors of the decline in Caribbean coral cover over the past 30 or more years based on the data available. Coastal pollution is undoubtedly increasingly significant but there are still too little data to tell. Increasingly warming seas pose an ominous threat but so far extreme heating events have had only localized effects and could not have been responsible for the greatest losses of Caribbean corals that had occurred throughout most of the wider Caribbean region by the early to mid 1990s.
So … will the reefs abide? Fortunately, we now know that waving our hands at CO2 is not the solution to the problems of the reefs—as with far too much of such CO2 hysteria, the underlying problems indeed have human causes, but they have nothing to do with CO2.
And that’s great news, because although we have no hope of changing atmospheric CO2, we can indeed do something about overfishing of parrotfish, and about coastal pollution. Fix those, and we’ll fix the reefs, and they will abide.
Best regards to everyone, and thanks for all the parrotfish, I’m off for Las Vegas.
w.
Yeah, yeah, you already know this: The usual polite request. If you disagree with something, quote the exact words. Only in that way can we understand what you disagree with.
My previous posts on the subject:
IUCN Press Release: From despair to repair: Dramatic decline of Caribbean corals can be reversed
IUCN Report: Status and Trends of Caribbean Coral Reefs: 1970-2012
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Thanks Willis. I knew that parrot fish made the beaches, but did not know they cleared the weeds.
This may explain why, on the reef I visited in the Philippines this year, the reef was overgrown with weed, while we dined on parrotfish in the evening. Sorry about that Willis…… 🙁
The locals explained that the parrot fish killed the coral by eating it. But if you are right, then the locals are completely wrong, and they are killing their reef through their ignorance.
R
And regards killing the reefs, in the Philippines, the locals eat anything and everything. They had basket after basket of little dried tiddlers about 3 cm long, in the market, mainly angel-fish types. This represents the overfishing of the bottom of the food-chain, which was probably another reason there were no large fish on the reef at all. The most boring reef I have ever visited – and nothing to do with Climate Change, that’s for sure.
R
The locals explained that the parrot fish killed the coral by eating it.
===============
In a sense they do, but the corals have evolved to take advantage of this, such that now the corals need the constant grazing to survive.
A similar situation occurs with grazing animals on land. They eat the grass, but in the process they also eat the young shrubs and trees that would otherwise grow to shade and kill the grass.
Thus, the grasslands have evolved with the grazing animals. Each needs the other to survive. The same situation with coral reefs.
I lived in Bermuda for several years and just to append the record sometimes the parrot fish poo creates pink beaches such as Elbow Beach in Bermuda.
Andy Revkin, in his Dot Earth blog on the NY Times — covered this thoroughly yesterday.
The parrotfishes in the Caribbean are not important for their sand production, but rather for the fact that they eat the ALGAE (not coral) that would otherwise cover and suppress the coral — they are cleaners, like the sea urchins. When they nip at the surface of the coral to eat the algae, they often get a bit of the surface hard “coral” (which is not the coral organism — see the diagram in w.’s The Reef Abides) — but really the non-living coral skeleton. It is the continuous cleaning by parrotfishes (there are some 90 types) that keeps the Caribbean reefs healthy.
The IUCN reports states specifically:
One commenter [Peter] makes an error to say that parrotfish eat coral and are thus deadly. I suspect he is referring to ciguatera poisoning. Ciguatera poisoning usually results from eating large carnivorous fish that have bio-magnified (bio-accumulated) toxins from eating a lifetime of smaller fishes, each containing a tiny amount of toxin — barracuda, snapper, amberjck and larger groupers are most often cited. Parrotfishes, particular the larger, older parrotfishes, in areas of high ciguatera danger, should be avoided, as they can, over their lifespan, bio-accumulate enough toxins from directly eating the dinoflagellates (the microorganism responsible for the toxin) which adhere to coral, algae and seaweed. Reading the IUCN report reveals that the eating of the parrotfishes in the Caribbean is what has reduced their numbers — and thus helped to degrade the reefs there. Apparently, we must assume, that ciguatera poisoning from parrotfishes is not a big issue in the Caribbean.
The IUCN report further confirms that the simple act of banning fishing — creating sea preserves — acts to restore the reefs. An example is the Exuma Cays Land and Sea Park in the Bahamas.
Of course, nothing helps if the local city is pouring trash, sewage effluent, and erosion-caused-silt onto the reef daily.
the Philippines, … The most boring reef I have ever visited – and nothing to do with Climate Change, that’s for sure.
==========
agreed. yet in those areas of the Philippines where the reefs are protected, such as Puerto Galera, the corals and fish are spectacular. so clearly it cannot be climate change. Otherwise reef protection would have no effect.
The Philippines is clear proof that climate change is not the cause of reef degradation. Those areas where the reefs are locally protected AND ENFORCED by law are quite simply world class. This cannot be explained by climate change, because climate change pays no attention to human laws.
The Philippines also shows the value of educating local people on how to maintain a healthy reef. How to leave areas protected to encourage tourism revenue and to provide a nursery to re-populate areas where fishing is allowed. Once the local people have a vested interest in the reef and understand how it works, they provide the necessary enforcement to drive off people that would otherwise harm the reef.
Teaching people that climate change is the cause or reef degradation is self-perpetuating. The local people will perc3eive that there is nothing they can do about climate change, so there is no reason to protect the reef if it going to die anyways. Might as well fish it out while you can.
So, in that sense, it is not climate change, but rather the belief in climate change that is killing the reefs.
So bleached corals can still be alive but are devoid of the symbiotic zooxanthellae algae.
==========
correct.
much of the alarm over bleaching is due to ignorance of the polyp life cycle and how prodigious they are at creating new polyps. the major problem for polyps is simply to find a spot to attach to, such as the newly cleaned area left by parrot fish browsing.
In a fashion it is like human children growing up and looking for a place to live. If you can’t find any place that is available, you are going to have to move somewhere else. Since every spot on the reef is already occupied with other corals, sponges, algae, etc., etc., you are going to have to keep swimming around and looking, until eventually you find a home or become fish food. However, if you are lucky enough to find a spot where parrotfish have been browsing, you can latch on and now have a permanent home for the rest of your life. From now on your time will be spent eating and creating new polyps.
Another aspect about bleaching is that it tends to be limited to the top and inside of the reef, in shallow waters. The face of the reef, where it meets the ocean and drops off, often to thousands of feet, is unlikely to bleach.
ferdberple said on July 7, 2014 at 7:26 am:
Well that will work out just fine, as I’ve noticed the TV telling me sea urchins are good eating. As in they’re pushing them now and I have never heard of them before as edible. Seems likely they’re set to become a new trendy exotic food item, suitable for harvesting by the tens of thousands.
http://www.cooksinfo.com/sea-urchin
Fish has become more interesting, recommended for eating at least a few times a week. Even though the cheapest breaded fish sticks are more expensive than basic ground beef per pound. Canned mackerel is still feasibly affordable, except I once couldn’t get some of the cats to touch it despite their being fiends for the stinkiest canned food.
And what has shown up in the local supermarket here in central Pennsylvania, away from anything resembling a large prosperous city? Frozen cleaned octopus. Breaded calamari rings are still something you’d offer your buddy as a prank, and they’re selling naked octopus? How do you prepare octopus, batter up and deep fry?
It makes me wonder just how over-fished the oceans have become for them to keep pushing this “exotic” stuff to persuade us the seas are still filled with endless bounty. Plain frozen fish chunks, tasteless stuff like tilapia and “swai”, are shipped all the way from South Africa and Vietnam, and can cost three times the going rates for fresh chicken. How can ordinary people afford to eat healthy by eating fish? Extra mayo in the tuna fish salad sandwich to stretch it out?
You don’t eat Parrotfish.
Parrotfish eat corals which contain neurotoxins – harmless to the Parrotfish, but deadly to humans.
=========
Ciguatera poisoning is a problem when eating any fish that feeds on the reef, or on reef fish. It probably won’t kill you, but it will make you wish you were dead. The toxin builds up in humans over time, such that you may be symptom free, and then have an attack after eating a very small amount of fish. Locals fear eating any large reef fish, and you will often only see very small reef fish for sale as a result. Not simply because there are no large fish, but because no one dares eat one.
There is no accepted treatment, though there have been reports of some success treating the condition with intravenous mannitol.
Because Ciguatera toxin is cumulative, a tourist may be symptom free after eating a fish that would otherwise cause severe poisoning in the local population.
Reply to ferdberple ==> See my comment regarding ciguatera in the Caribbean, via-a-vis parrotfish.
Reply to ferdberple ==> “Locals fear eating any large reef fish, and you will often only see very small reef fish for sale as a result. Not simply because there are no large fish, but because no one dares eat one.”
Where are you talking about? I suggest that it is both – no large fish and in some areas, people know better than ti eat them – but it depends on species.
In the DR, PR, and the Virgin Islands, and the Exumas (Bahamas, outside of the sea park) this is simply not true at all. Locals eat everything — fishermen fish (hook-n-line, traps, spears) everything bigger than a sardine, fishing the same local reef their fathers and grandfathers fished — in these high population areas, all the BIG reef fish are gone. Locals tend to know where ciguatera problems are and avoid certain fishes from those areas — few, for instance, will eat large barracuda.
According to “Ciguatera in the Eastern Caribbean“:
and
The report linked is a pretty complete overview of the subject for the Caribbean.
Note that pelagic fish (ocean going, not local reef fish) are generally excepted (IMHO, barracuda are always to be suspected).
A relevant item in the Weekly Climate and Energy News Roundup:
Lessons from the shop floor
By John Shade, Bishop Hill, Jul 4, 2014
http://bishophill.squarespace.com/blog/2014/7/4/lessons-from-the-shop-floor.html
Funnily enough, I understand that large-ish reef fish species on the Queensland (Australia) reef complexes build up ciguatera, especially the pelagics such as Spanish Mackerel but on the other side of the continent (Western Australia) large fish such as Red Emperor are quite ok to eat. (Guilty!)
Anyone know why this is so?
Some species when large such as Chinamen are more prone to ciguatera.
But I’ve only ever eaten plate-sized reef fish in Qld.
“I’ve proposed that atoll nations declare the parrotfish as their national bird”
SkS will now be running an article pointing out that a parrotfish is not a bird…
When I first dove into the ocean my first question was “what the heck is that crunching sound” and it was parrotfish munching on the corals. I don’t think the average land bound person understands the enormous role parrotfish play with the reefs and islands. If there is ever an effort to get the message across to the masses with something other than press releases, it would be a good idea to play those crunching sounds in the background, once heard it is not forgotten.
Reply to Mick In The Hills ==> Not sure what the situation in Queensland is .. I have visited the GBR but not when concerned about ciguatera. See this link on ciguatera in the Caribbean. Maybe you can extrapolate from principles explained in it.
Generally, pelagic (sea going) fish are not subject to ciguatera — however, in the Caribbean, fish such as barracuda, which feed both on the reefs and in the open sea, are avoided by those in the know — especially larger ones, as they have certainly fed on the reefs during their long lives.
kadaka (KD Knoebel) said @ur momisugly July 7, 2014 at 11:34 am
The octopi I eat have tentacles about the thickness of my thumbs. Beat thoroughly with a meat hammer. Marinate in lime juice and olive oil overnight. Char grill on the barbecue. Greek salad to accompany is optional, but highly recommended. Absolutely delicious and my favourite dish when dining at The Republic Bar in Hobart 🙂
Great post Willis -thanks. Some thoughts on the foregoing comments: Reefs are super sensitive to a numbers of factors – light, temperature, suspended sediment, nutrients and salinity.
Dinoflagellate zooxanthellae algae are in a symbiotic relationship with reef forming corals and are light dependant. Therefore reef forming corals do best in clear water. Suspended silt from rivers both reduces light and in some species can clog coral feeding apparatus. Corals are also temperature sensitive. In the cooler waters around Bermuda only 20 or so species can survive. In the warmer waters of the Caribbean up to 70 species can be found. However in some of the warmest ocean waters in the western Pacific there can be as many as 700 plus species of reef building corals. Corals and their symbionts are highly sensitive to nutrients like nitrates, phosphates etc and in high nutrient settings such as river mouths or in areas where untreated sewage is discharged, this fertilization of the ocean promotes the growth of algae which will outcompete corals. This is why parrotfish, urchins and other grazers are so vitally important in keeping the reef “clean”. Parrot fish rasp off algal filaments growing on dead coral and coralline algal substrates and in doing so remove some of the calcium carbonate substrate. This is what they and sea urchins poop out and it can form a significant percentage of beach sand. However that sand will also consist of wave abraded coral fragments and fragments of other hard bodied, calcified reef dwellers as well as shell fragments from things like molluscs.
The pink sand of Bermuda which were commented on are pink because of a bright red single called foraminiferan Homotrema which grow on the reefs there and are detached by storms and by grazing parrot fish and can constitute a large fraction of the beach sand especially on the south coast.
In the early 80’s many Caribbean reefs suffered an algal infestation when the spiny sea urchin population was decimated by a wind-borne virus thought to have originated in the Sahara. Urchin populations are slowly recovering which might be linked to the recovery of many reefs there.
In my experience modern corals can easily adapt to short term temperature changes – some have the ability to swap out zooxanthellae as temperatures rise. The biggest threat is from overfishing, “over-tourism” and pollution from untreated sewage which encourages algal growth and coral death. As mentioned above it is these things that we should be putting our effort and money into.
As for coral atolls threatened by rising sea levels, growth of coral and other reef sediment producers can easily outpace any known rate of sea level rise. Darwin was the first to explain the formation of coral atolls around subsiding volcanic peaks and deep drilling has subsequently confirmed that the reefs forming the foundation of coral atolls are hundreds to thousands of feet thick and have easily kept pace with rising sea levels which were some 120metres lower during the last glacial maximum. Island states would be well advised to maintain healthy reefs because these will be the source of sediment which will keep the island above sea level no matter what that rate of rise will be.