Networked Blogs
Twitter and News feeds
Search this site
Navigation

Entries in reef (9)

Friday
May212010

The Travel Bug bites hard, but it hurts so good

Just once in life I did the totally reckless thing of looking at a photo (in a Lonely Planet guide, if I remember) and saying "Thats it, I am going there, now" and then doing exactly that.  The place was Leh, which is in region called Ladakh, in the province of Jammu & Kashmir in Northern India.  Not once did I ever regret that decision; Leh was one of the most magical places I ever visited, probably made moreso because of the liberating decision to go half way round the world to see it and the good buddies I shared the experience with.

Well, I feel the same bite about Saba in the Netherlands Antilles.  Every time I look at a photo of that little volcanic speck and imagine the hair-raising landing at the airport, followed by the equally follicle-lifting drive through a myriad switchbacks clinging to the side of that impossibly steep volcanic plug, I can barely resist the urge to just walk out the door, head for Hartsfield-Jackson and jump on a plane.  I have assiduously suppressed these feelings for years in favour of pedestrian realism, but now PLoS One has published a series of papers about the diversity of critters on the bank reef adjacent to Saba.  How am I supposed to resist that?  Thanks a lot PLoS...

Somebody help a travel junkie out; either convince me to go, or talk me down!  Ever been there?  Whats it like?

Picture from Throwingpoo.com (I kid you not)

Monday
May172010

Seaweeds and corals go through the media meat-grinder

ResearchBlogging.org“If it bleeds it leads” is a common meme in the journalism field, but when it becomes the mantra of science reporting, sometimes the real message gets lost in translation. Unfortunately, so it is with a new paper from Doug Rasher and Mark Hay down the road at Georgia Tech. In their work, published in PNAS this week, they show that algae from coral reefs can have toxic effects on adjacent corals including bleaching (expulsion of the symbiotic algae that are responsible for much of the corals success) and even death. They provide evidence that these effects are mediated by lipid soluble compounds and that they are much reduced on reefs that have healthy herbivorous fish populations to keep the algae in check. There, I summarized their work in 2 sentences. It’s disappointing, then, that the NSF (NSF for goodness sake!) turned that into “Killer Seaweed: Scientists Find First Proof that Chemicals from Seaweeds Damage Coral on Contact”. Unfortunately, that kind of catch-phrase gets picked up all over, so that MSNBC ran with “Killer seaweed threatens corals: Innocent-looking species turns into an assassin of nearby reefs” (assassin? Really?!). The Georgia Tech website went with “Research shows that chemicals from seaweed kills corals on contact”. Not as dramatic perhaps, but more reasonable. Ed Yong at Discover Blogs chose to emphasise the fish side of the story: “Overfishing gives toxic seaweeds an edge in their competition with corals”; both these seem fine to me, but honestly, I don’t know what’s wrong with using the title of the paper “Chemically rich seaweeds poison corals when not controlled by herbivores”. I think Rasher and Hay did a good job distilling the essence of the paper into a punchy and information-dense title. In any case, its frustrating to see crux of a paper lost in attempts to sensationalise the story, as did all the outlets who went with the “killer seaweed” theme.

Putting aside the press treatment, I think there’s an important part of the story missing from this paper. In it, Rasher and Hay report that in the absence of herbivores, 40-70% of common seaweeds cause bleaching of a model coral species (Porites), depending on where you are. If you average that – 55% - then roughly half of seaweeds were toxic to their model coral. On this proportion and their comparison of overfished and non-overfished reefs, they base the conclusion that these algae are bad for corals, that herbivores suppress the algae and, therefore, that overfishing will increase coral declines by allowing toxic algae to proliferate. All of these seem reasonable ideas, but I kept asking myself: what about the reciprocal effect? What percentage of corals are antagonistic to algae? If, say, half of all corals can damage adjacent algae, then the net effect of all this antagonism at the largest scale is zero. If half of algae kill corals and half of corals kill algae, it could be zero sum. This seems important to me, because it would undermine the conclusion that overfishing of herbivores will necessarily lead to declines in reef corals. Indeed, I could make the reverse argument that overfishing of corallivores (fish that eat corals) might lead to proliferation of corals and therefore the decline of reef algae. We just don't know because that work hasnt been done. 

Of course, you can’t include everything in a single paper and I would expect the authors to respond to my point by saying that the experiments I describe were beyond the scope of their project. But I think it could have been a better paper if they acknowledged that there’s another possibility that cannot be excluded, based on work that’s yet to be done.

Rasher, D., & Hay, M. (2010). Chemically rich seaweeds poison corals when not controlled by herbivores Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.0912095107

Saturday
May152010

Calling the corals home

Ed Yong at Discover Blogs has a great post up about a PLoS One paper describing how coral larvae find their way back to the reef from the plankton, using sound.  This is a remarkable ability for a tiny ciliated ball of cells, demonstrated through a nifty experiment where the scientists played sound from different directions into a dish of tubes containing coral larvae and showed that they moved towards the speaker playing sounds from a reef.

Putting aside the remarkable little larvae, maybe we shouldn't be surprised. Anyone who has ever put their head underwater on a reef, especially a Pacific reef, can tell you they are noisy places.  I always thought it sounded like frying bacon - a sizzling crackle of clicks, pops, scrapes and cracks, courtesy of snapping shrimps, parrotfish and a myriad other beasts.  The first time I heard that sound I remember being startled, and then amazed.  Serene underwater scenes?  Serene, my butt!

Thursday
May062010

Something eerie is happening, down Mexico way...

After a youth spent on the dry side of the water (another post for another day), I have come to love SCUBA diving with a passion. I also love art and photography projects that explore the way nature reclaims all things, in time. (My wife dubbed this obsession “elegant decay” – stuff that’s falling apart and looks good doing it.) Soon there’s going to be an opportunity to combine those passions in one of my favourite places – the Yucatan Peninsula of Mexico. Artist Jason de Caires Taylor is installing the largest underwater sculpture garden in the world, in the waters adjacent to Isla Mujeres, not too far from Cancun. I find this idea captivating. Normally the human world and the underwater world are so forcibly separated by medium, light and a host of other factors, and this project will bring them into eerie juxtaposition. The proposed 200 human figures reclining, working, or even riding a bicycle, contrasting with the reef, fishes and rippling filtered sunlight is just great. How do I know, if it hasn’t been built yet? Because he’s already done similar work on a much smaller scale in the Keys and Grenada.

Some might argue that this stuff is visual pollution of a reef that should just be appreciated for the biological wonder that it is, but I couldn’t disagree more. Especially when the reef begins to claim the sculptures as its own, in time incorporating their forms into its structure and adding its own patina of life, like a painter stepping back from the canvas and daubing the final blobs of color here and there. By then, we and the reef will be one and the same, and that idea really resonates with me. Installation begins in June. I can’t wait to see it when I am down in Mexico this summer.

What do you think – art or pollution?

Tuesday
Apr272010

Me and Terry Hughes, we got Kwan

This is a little spooky. Terry Hughes of the Center for Excellence in Coral Reef Studies in Australia, whom I know only vaguely, has been quoted on the topic of the Shen Neng 1, that Chinese coal ship that ran aground on the Great Barrier Reef. His somewhat dismissive tone sounds creepily like my recent rant on the subject.

He said:
"The [Shen Neng 1] ship grounding, in the scheme of things, is not a major incident. It's bad if you happen to be one of the corals the ship parked itself on, but it's tiny in the face of the real problem: global warming."

I said:
"I am not worried in the slightest about this incident.  Not that its a good thing - far from it - but this accident is nothing more than a tree, obscuring us from seeing one big and scary forest [burning fossil fuels]."

Terry, you're my Ambassador of Kwan.

Thursday
Apr152010

Q: When is a ship like a tree?

A: When you can't see the forest for it.

You may have followed some press in the last week or so about a Chinese coal ship, Shen Neng 1, that ran aground on the Great Barrier Reef and spilled some of its fuel oil.  This has caused a regular frenzy in the Aussie media and the global conservation and environmental news-o-sphere.  There have been all sorts of calls for prosecution of the shipping company and new stringent regulations for the transport industry and so on, along with dramatic accounts of the damage the ship did and the risky salvage operation that came next.  But you know what?  I am not worried in the slightest about this incident.  Not that its a good thing - far from it - but this accident is nothing more than a tree, obscuring us from seeing one big and scary forest.

The main reasons I am not especially bothered by the Shen Neng accident are that (1) it affected a very limited area - the G.B.R. is really B.I.G. and one ship can only damage so much of it; and (2) it was a single event in time - this was not a process or an ongoing problem, but a singular disturbance.  Science shows us that the GBR, and reefs in general, are amazingly resilient to violent disturbances like this; a decent cyclone can literally turn a reef upside down, and a couple of years later you'd never know the difference.  Indeed, periodic disturbances may  be really important for maintaining a healthy reef ecosystem.

No, the Shen Neng is just a tree, obscuring us from seeing the forest that really threatens the future of the GBR and all reefs.  Its not the 2km gash that the hull cut in the reef, nor is it the tons of fuel oil leaked into the water; it's the very concept of burning that fuel oil, and burning the thousands of tons of coal that the Shen Neng 1 was carrying.  When you consider all the other ships and all the coal and fuel they were carrying that day and every day, and all the cars in the world, the power plants and so on ... ach, you get my point.  THAT'S what we ought to be worried about, because both of the main effects of increased atmospheric CO2 - warming and ocean acidification - will likely result in unrecoverable damage to All reefs. Everywhere. In our lifetime.  Warming is directly linked to lethal bleaching events, while acidification disrupts the ability of reefs to lay down their skeleton and grow.   Oh yeah, and lets not forget the drowning effects of sea level rise, too.  The more I think about it, the more it seems that jumping up and down about the Shen Neng is hypocritical (coal is one of Australia's biggest exports, after all) and akin to complaining about the deck chair arrangements of another, even bigger, ill-fated ship.  (Ironically, if Titanic sailed today, she probably wouldn't have to worry about icebergs...)

Of course, its a false dichotomy, we should be worried about BOTH the Shen Nengs of the world AND the global climate change/ocean acidification.  But I only have so much energy/capacity for worrying about these things, so with a limited anxiety budget, I feel compelled to focus on the bigger issue and what (if anything) we can do about it - to try to reduce consumption and to try to make sensible decisions that are mindful of how much energy is involved and what the broader impacts might be.

In other words, to worry about the forests - and let the trees take care of themselves.

Saturday
Mar272010

The ghost of fishers past

The folks you see out on their boats on the bay are not the only ones fishing; those who came before them still get a slice of the action, as this recent article about the retrieval of "ghost gear" from the Chesapeake Bay illustrates.  In many trap-based fishing industries, like lobsters and crabs, a significant number of traps are lost during the course of regular fishing efforts.  In addition, when a fishery turns bad, as happened in the Long Island Sound lobster fishery in 1999, some fishers cut their losses, and their marker floats, quit the fishery and just leave their gear where it is on the bottom of the bay.

The problem is, ghost gear like this keeps on fishing, long after the fisher has moved on to other endeavours.  The design of the trap continues to attract animals, even without bait, because the trap is basically a refuge or cave.  Those that enter are unable to leave and as they die they may act as bait to attract yet more animals to feed on their body.  In this way, the trap becomes a sort of "biomass black hole", sucking in animals from all around, for as long as the trap holds together.  Nets can ghost fish too, especially gillnets or any kind of trawl that can trap fish or strangle a reef

We used to trawl up ghost lobster gear all the time when I was working in Long Island Sound.  Indeed, few days on the water went by without snagging someone's old gear at some point, which speaks to the density of gear that's out there in some inshore waters.  I'm glad the fishers and the resource management agencies are working together to address the problem, because its one of those awful chronic out-of-sight, out-of-mind issues that can erode a fishery despite everyone's best efforts to manage things properly.  If you find ghost gear, call your local DEP or DEC, even the EPA, and let them know so they can come and retrieve it.

Picture of ghost gear on a coral reef from NOAA

Friday
Mar262010

Lionfish - more spectacular than your average invasive, but still a right pest.

When we think of invasive species, flamboyant fish from coral reefs are not usually the first thing that comes to mind.  Indeed, if you put together a list of characteristics of successful invasive species (like this one), "boring" would probably be close to the top, along with being quick to reproduce, not fussy about what you eat, having a large natural range, a great tolerance for extremes in the environment, and lacking natural enemies such as predators or parasites.  Think of some of the most successful invaders and decide for yourself if these predictions hold true: carp, starlings, mosquitofish, rats, sparrows, mice, rabbits, dogs, cane toads, cats, foxes, kudzu, chickweed... 

All this makes the invasion of the Atlantic seaboard by the Pacific lionfish, Pterois volitans, all the more remarkable.  Lionfish are flat-out spectacular!  Long prized as an aquarium specimen, they have bold stripes that spill over onto their fantastically long and showy fins; their scientific name even means "fluttering wings".  The sheer beauty of lionfish doubtless plays a role in how they came to invade the Atlantic in the first place; most likely they were an escaped or released aquarium species that found itself able to survive quite nicely in the conditions of the coastal Atlantic.  The beauty of lionfish conceals a dangerous secret - venomous spines on their dorsal (back) and pelvic (bottom) fins.  While they won't kill a person; they cause excruciating pain.  I've never been stung by one, but I have been stung by related scorpionfish (most recently the short-spined wasp fish) and the feeling is not one I'd care to go through again!

Over the course of just a few years, mostly since 2000, lionfish have spread dramatically along the coast of the Atlantic, from North Carolina down to the southern Caribbean and Mexico's beautiful Yucatan peninsula.  Typically considered to be a rocky or coral reef species, they've now been found swimming in the intracoastal waterway; that labyrinth of salt-marshes, channels and estuaries, engineered to allow safe passage of boats along the US coast in wartime.  This is sort of an unusual location, but it speaks to the adaptability of this remarkable fish.

So, what to do about such an animal??  Well, that's a tough one.  Invasive species (or more accurately, moving species around) are one of the greatest impacts humanity has had on natural environments, and there are very few cases where we have successfully eradicated or controlled an invasive (but see prickly pear in Australia), more often they just become part of the furniture and we get used to their impacts on the local ecosystem.  Introducing natural enemies (diseases, predators) like they did for prickly pear is a dangerous game; if you tried to get the Cactoblastus moth introduced to Australia in these days of stricter biosecurity, you'd almost certainly be denied.  You can easily get into a "spider to catch the fly" situation too; in fact that's how cane toads were introduced to many places - to control sugar cane beetles (which they suck at).  Perhaps the best approach is to do what we do best - create a market that will promote human efforts to exploit them, and then rely on the Tragedy of the Commons to do the work for you.  This has already been proposed with Asian carp.  Fortunately, it turns out that lionfish are not only spectacular aquarium fish, but also delicious in a white wine sauce.  I am sure that if we set our minds to it, we could do as good a job wiping out this species as we have with so many others.  So c'mon everyone and grab a fork; Save a reef - eat a lionfish, today!

(Photo and graphic from NOAA)

Tuesday
Dec152009

Feral fish

No, not the long-haired hippy type, I mean those that are not indigenous to a habitat.  USGS and NOAA just co-published a pictorial guide to the non-native fishes of Florida.  This is doubtless part of the heightened awareness of this problem in US waters and, indeed, worldwide.  Lord Robert May recently cited invasive alien species - along with climate change, over-exploitation, and habitat destruction - as the most important causes is species extinctions in the biodiversity crisis.  It seems marine species are not immune to this effect; even though the diversity-stability hypothesis predicts that reefs ought to resist invasions.

My PhD thesis was about what happens to the parasite fauna when a fish gets introduced to a new habitat, so this subject is close to my heart.  To learn more, read about the subject as reviewed by my colleague Mark Torchin here: