Networked Blogs
Search this site
Navigation
Twitter and News feeds

Entries in coral reef (22)

Thursday
Jan272011

Attenborough and deep sea corals

There’s a new website up that talks about deep sea corals, including one of the species the science team has been studying here in Brazil - Lophelia.  Its even called Lophelia.org and was put together by some Scottish scientists who discovered Lophelia reefs off the coast of Scotland in 2003.  It’s very comprehensive and well worth a visit, and it’s recently earned an endorsement of the doyen of nature documentaries, Sir David Attenborough.  One of the weird things to think about when you click on over is that the same corals that form those reefs in Scotland are forming deep reefs here in Brazil.  How is that possible?  I mean, one is in the chilly North Atlantic, while the other is in the tripical south Atlantic.  Well, if you think about it, once you go deep, it doesn’t matter where you are, it’s always gloomy dark and cold!  For example, even though the surface temperature was in the high 20’s (low 80’s for the US readers) here in Brazil, the temperature down where the sub was going was 7-9 dgrees (around 45).

A Dendrophyllia alternata (originally mislabeled here as Lophelia) colony collected from the Abrolhos platform

The new website is a great resource for learning more about Lophelia and other deep coral reef species and just maybe it will help us all broaden our horizons to start considering coral reefs in a context broader than the insanely colourful shallow reefs that most easily comes to mind when you hear the phrase.

Monday
Jan242011

A sobering sight at 600 meters

On the very first Johnson Sea Link dive during this cruise, the very second thing seen on the bottom was the bottle shown in the video below shot by Johnson Sea Link crew.  This was observed at 600m (technically, it was at 1,850ft), in soft calcareous mud, over 45 nautical miles from land and 60 miles from the nearest town.  On the next dive, the scientists observed a lot of old longline fishing gear wrapped around the reef structure.  It seems, even in this remote location, which has never before been visited by humans, trash from human activities elsewhere has made its mark on the habitat.  It is a prominent and disturbing reminder of our impact on even the unseen parts of the planet.  I can only hope that this bottle becomes a home for some small thing, or that it becomes crusted over with coralline algae such that one day it is simply a bottle-shaped rhodolith

Monday
Jan242011

Seized by a sneeze - more from Kristie Cobb Hacke

AD - Its clear to me that Kristie is a repressed zoologist!  Her pure joy at the sight of dozens of tiny brittle stars attached to a sea fan is the kind of emotion that drove many of us into marine science in the first place.  But don’t take my word for it…

________________________________

When I was a kid I used to spend hours thinking about how small we are in a really big world. I would often ponder “what is at the end of the universe?” I would amuse myself by thinking things like “it’s a brick wall” and then assume if you walked around or knocked it over there was always something on the other side. I would have this same thought again and again sometimes stopping to pause and wonder if it is something just like a big brick wall and there is no other side. When I was in high school these thoughts were shared by some of my friends as we circulated and chatted about Douglas Adams and his version of the universe and the restaurant at the end.

Another popular thought of mine was that earth was created by a giant sneeze. Sometime in middle school biology a teacher posed the thought that there could be whole universes in something as small as a pin-head. I had this great vision of the giant humans, one standing in front of another being seized by a sneeze. This uncontrollable sneeze produced projectile droplets that landed on the other person’s glasses. Although the term “yuck” is the first thing that comes to mind the second was always….”what if that just created a whole universe?” Would some small organism in that universe consider the edge of the droplet the end of the universe? Would they push on to see what was on the other side? Would they live and die a whole lifetime in the instant between the sneeze and the inevitable wiping of the lens?

From the collection boxes of the Sea Link II the scientists brought up a bio-box of goodies. Their samples included a beautiful gorgonian sea fan. As they unloaded, documented and photographed the various items, they pointed out many beautiful teeny-tiny brittle stars on the single fan sample. One of the researchers suggested that the sample piece contained more than 30 of the sea stars. Each of the sea stars was amazingly blended to hide themselves among the thin fan structure of the coral. Their fragile thin legs curled around the fan and, when coupled with their patterning, it created the perfect camouflage. The researchers were amazingly accommodating and allowed me to touch and handle one of the sea stars and a piece of the coral. As I carefully unwound an arm I had a stunning flashback to the brick wall and the sneeze. I wondered instantly if to these sea stars is the edge of their universe the single fan, the whole coral colony, the structure to which it is attached or some expanse of sea floor?

Camouflaged brittle star attached to a gorgonian

When you consider the ocean as a whole it is amazing to think about all the millions of places that are yet to be discovered. Not to mention the uncountable species yet to be recorded. There are new depths known only through scans just waiting to be explored by humans. This journey has allowed time for conversations about new technology being created and innovative ways to use existing technologies or commercial vessels for research applications. As each of these becomes available and is applied it will undoubtedly lead to new discoveries. As this continued, in our lifetimes alone, there are bound to be millions if not trillions of questions to be asked and hopefully answered. Although I doubt the answer to life the universe and everything is as simple as “42” and I certainly cannot claim to know if there is a brick wall waiting at the bottom of challenger deep just waiting to be knocked over. What I do know is that research and its concrete ability to pose and then answer questions is incredibly important to our full comprehension of both the universe and the deep.

AD - This relationship between the brittle star and the sea fan is a great example of how little we know about symbioses in the oceans.  Clearly the two organisms are living in close association, but in what manner?  Is it pure parasitism, whereby the brittle star benefits and the sea fan is damaged?  Or is it commensalism, where the brittle star benefits and the sea fan is indifferent to its passenger?  Is it maybe possible that there is some sort of mutual benefit that we are unaware of?  As a parasitologist by training, how little we know about the these associations makes it hard for me to define my own field.  So, while Kristie’s vision is a little broader than mine (scaling up from brittle stars to the edge of the known universe!), I mostly grapple with smaller questions of who makes out better in this little biological transaction, and how does the sum of those transactions across the diversity of animal groups serve to reinforce or undermine stability in the whole ecosystem.

Sunday
Jan232011

Dia 2 Campanha Seward Johnson - A guest post from Gustavo Duarte

Gustavo Duarte is a PhD student with the Abrolhos expedition.  Here, he describes for Portuguese readers, Day 2 of the research cruise.  Gustavo has a blog at IPAq; you can read more there.

_________________________________________

Ontem o que fizemos basicamente foi combinar toda a estratégia de coleta para hoje. O submersível estava agendado para descer as 8:00 da manhã com dois pesquisadores: Clovis Castro, meu orientador do Museu Nacional e Shirley Pomponi, do Harbor Branch, além do piloto e do co-piloto.

O mergulho foi um sucesso total. Foram trazidas várias espécies de mar profundo. O destaque foi uma belíssima estrala do mar, vários caranguejos bem diferentes, um lirio do mar e várias espécies de corais vivos.

A temperatura da água durante o mergulho foi de 6˚C aos 700 m subindo para 8˚C aos 450 m. Na verdade o submersível desce até a profundidade máxima do mergulho e vai junto ao fundo até a profundidade mínima e então sobe a superfície.

Os corais estão nos aquários que estão por sua vez dentro de uma câmara fria, a tal “environmental chamber”. Lá eu tenho água do mar corrente saindo de uma torneira. Montei os fragmentos num suporte usando superbonder gel e depois durepoxi. Se sobreviverem até amanhã vou alimentá-los com naupilios de artêmia e plancton coletado pelo navio.

Deu muito trabalho triar todo o material, veio muita coisa diferente. Mais a noite eu tento postar as fotos. Agora estamos fazendo coleta de água em várias profundidades para medir nutrientes, penetração da luz, níveis de clorofila, temperatura, tudo isso de acordo com a profundidade. Um pesquisador a bordo vai filtrar esta água e congelar o material a -80˚C para análise genética dos microorganismos presentes na coluna d’água. Para isso estão usando um CTD com uma rossette.

As 4 da tarde faremos um mergulho mais raso, que começará em 120 m e terminará em 70 m. Coletaremos amostras de corais com zooxantelas e eu medirei a resposta fotossintética destes organismos. Depois, usando uma serra copo, vou retirar uns plugs de cada coral e no laboratório do Rio iremos medir a clorofila das amostras, a microbiota associada bem como uma contagem de zooxantelas.

Com isso esperamos conhecer um pouco mais destes corais que conseguem fazer fotossíntese em regiões tão fundas.

Sunday
Jan232011

Diving is like a box of chocolates...

…You never know what you’re going to get.  In this video, the Johnson Sea Link (JSL) is recovered after the first dive of the Abrolhos2011 Expedition.  Brazilian scientist Clovis Castro was aboard with HBOI scientist Shirley Pomponi. 

Afterwards, the science team went to work processing invertebrate samples including gorgonians, the hard coral Lophelia, and a range of brittle stars, crinoids, urchins and miscellansous crustaceans

The Brazilian science team evaluates their first samples. L-R Gustavo Duarte, Clovis Castro, lead scientist Rodrigo Moura and Ronaldo Francini-Filho

 

Reporter Glenda Koslowski with Brazilian scientists (L-R) Gustavo Duarte, Clovis Castro, Rodrigo Moura and Ronaldo Francini-Filho

 

PhD student Gustavo Duarte takes Lophelia fragments for cultivation

 Alex Bastos with a fine carbonate mud sediment core from 600m

 

Sunday
Jan232011

Rocking the Abrolhos

This is the first post from onboard the R/V Seward Johnson, currently at 18 deg 6 min S, 38 deg 25 min W, somewhere off the coast of Bahia State, Brazil.

_______________________

Alex Bastos likes rocks.  Biologists may scoff, but the truth is that rocks and geology provide the context for biology in the oceans, much the same way as a playing field provides the context for a game of football.  In an expedition concerned with coral reef ecology, then, it’s important to have a thorough understanding of geological processes, because they shape the history of the reef and can help predict its future.  Dr. Bastos, who hails from the Federal University of Espirito Santo, is a marine geologist with a special interest in the Abrolhos.  He is trying to understand what has happened in the prehistoric past and what is happening on the reef today by reading the shape of the bottom features (what geologists like to call morphology) and reconstructing a story and past and present events on the Abrolhos shelf.  Scientists call this sort of activity “inferring process from pattern”, and in terms of marine geology it brings with it some special challenges.  The biggest of these is that, for the most part, Alex can’t see the morphology he wants to study, certainly not as easily as a terrestrial geologist might fly above a mountain range and read the faults and synclines of the landscape to understand what geological forces shaped the land.  No, he has to construct his story a piece or two at a time, like putting together a jigsaw puzzle, often from indirect evidence.  He gets his jigsaw pieces from some pretty cool technology though, including seismic equipment, side scan sonar and by drilling cores out of the sediment.

Side scan sonar is an especially great tool that has become really popular in research circles in recent years.  It uses sound to reconstruct bottom morphology by sending out high frequency noises and then gathering back the echoes off the bottom, much the same way bats find food.  What makes side scan different from regular sonar is that instead of aiming the sound straight down under the boat, it is directed away to each side.  Since the sound hits objects and bounces back at an angle, any structure of any height will cast a sort of sound “shadow” on the side facing away from the boat.  The resulting image is a plan view, but with shadows that reveal shapes and structures, rather like taking a photo from an aeroplane late in the day, when shadows are long on the ground.

Side-scan reveals and ancient river channel. Img: Alex BastosBy combining studies of morphology with reconstructions of sea level at different times in geological history, Alex tells a story about the way the Abrolhos platform evolved.  Around 40 million years ago the main playing field was established by a flood of volcanic basalt that spread out to create the basis of the platform.  In the ensuing geological periods, carbonate rocks (i.e. limestone) were deposited, implying that reefs existed there at times in the distant past (my assertion in a previous post that there were no reefs on Abrolhos before 8,000 years ago was wrong).  During the last ice age, the sea level was over 100m lower than its current height, so much of the platform, including the locations of all the current shallow coral reefs, was above the surface.  At that time, a central depression in the platform was probably still filled with water, forming a shallow coastal lagoon opening to the south.  The Caravelas River probably drained into this lagoon from the north, cutting a number of different channels through the limestone as it meandered over time.  The river also provided a source of sediment that fanned out off the edge of the platform from the mouth of the lagoon.  All three of these features – the shallow depression, the channels in the limestone and the sediment fan – are still there on the bottom of the sea and help to tell the story.  At the end of the last ice age came the last great transgression, when sea level rose to approximately its current levels.  The entire platform was flooded, and corals once again colonized the platform and began to grow up towards the surface to where we see them today.

How Abrolhos might have looked during the last ice age; note the central lagoon opening to the south

Current bottom topography of Abrolhos; note central depression due south of the islands

Holocene sedimentary processes.

Unfortunately, morphology only gets you so far.  Knowing the history of the platform, many of Dr. Bastos’ questions now relate to what has happened since the last transgression, during the most recent geological period (the Holocene), and most of these need other methods to answer.  These questions include “Is all the sediment on the platform a relict of geological history, or are sediments actively being deposited to this day?” and “If they are still being deposited, do they come from the land via the river, or are they produced in the ocean by corals, coralline algae and other organisms?”  To answer these questions, Alex will use a combination of seismic methods and sediment cores.  Seismic surveys provide indirect evidence of the nature of sediments below the surface of the sea bed, and these can be calibrated or “ground-truthed” by taking sediment cores that will reveal a timeline of sediment history on the platform.  These geological questions played a large part in the choice of sites for the main transects on this expedition.  One is to the south, in the mouth of that ice-aged lagoon, on the edge of the shallow-sloping fan of sediment.  The other is in the north, on a much steeper shelf break where the platform gives way to the deep sea beyond.  These two locations not only have profoundly different geology, but it’s likely that organic processes differ between them too, as we shall see in a future post.

Applying the lessons

Alex was telling me that one of the more satisfying aspects of his work is translating geology data into benthic (bottom) habitat maps.  In other words, taking all that information from the sonar morphology, the seismic data and the sediment cores, and mapping out what different parts of the platform are like on the bottom.  This is important, because once scientists can say with confidence that Area X is a rhodolith bed, or Area Y is a steep-sided valley, then they can predict with good accuracy what sorts of organisms will live there.  That sort of information is of critical value when deciding where to take biological samples and even more so when the Ministry of the Environment needs to make decisions about the boundaries of protected areas, which they are currently doing.  In this way geology plays a very important role in both the biological sciences and in conservation decision making.

Friday
Jan212011

Getting down to the nitty gritty

How deep can we go?  How can we collect fish?  How much water can we sample at once?  These are just some of the questions that filled today’s planning session in Vitoria for the Abrolhos 2011 expedition.  They’re not straightforward questions to which some resident authority has a simple answer.  No, when you’re planning work between 300 and 3000 feet down, no questions are simple, and nor are the answers easy; rather, they are crafted through a careful group discussion of what’s a priority, what’s possible, what’s practical, and what we have time for.  In other words, its not all The Life Aquatic, its large parts careful planning and preparation.

The day started with presentations from representatives of Cepemar, Harbor Branch and the Rosenstiel School of Marine Science at U. Miami.  After that, Rodrigo Mouraled the planning session where we talked reef biology for hours, fueled (as all the best science chats are!) by shots of excellent Brazilian coffee.  Dr. Moura is a faculty member at Santa Cruz University and a consulting scientist with Conservation International, who have a substantial marine conservation program focused at Abrolhos.  He explained all the things that make Abrolhos unique, from the 40,000km2 platform on which they occur, to the unique fauna and dominance of shallower reefs by the endemic coral Mussismilia braziliensis, to the unusual mushroom formation of these reefs (chapeiroes), and finally to the history of human impacts and conservation efforts surrounding these unique ecosystems and the deeper and less-known seafloor habitats around them.  The Abrolhos Marine National Park was the first marine national park in Brazil, established in 1983, but like many reefs it faces its fair share of threats from pollution, global climate change and marine development.

 Suitably up to speed on the history and context for the expedition, the next speakers were the 8 principal investigators to give details of the motivations for their respective parts of the expedition, and to outline their specific sampling needs.  Alex Bastos, a geologist from the Federal University of Espirito Santo, talked about the geological history of the platform, how its central depression was likely once a shallow coastal lagoon during the last ice age, and how taking samples of sediment from the bottom will explain more about how the reef came to be and how much it contributes to calcium carbonate production in that part of the Atlantic. Paulo Sumida from the University of São Paulo explained how organic matter (carbon based material either secreted from living organisms or leftover by dead ones) is distributed unevenly across the platform, with more in the south and less in the north.  We learned from Mauricio Torronteguy’sgroup at Cepemar how water sampling and measurements of the properties of the water overlying the reef would be used to provide a better understanding of the biology taking place on the reef.  Microbiologist and geneticist Fabiano Thompson from the Federal University of Rio de Janeiro explained what has been learned about the importance of Vibriobacteria on the reef, both as potential agents of disease in corals and, surprisingly, as possible agents of photosynthesis; i.e. food production from sunlight.  Vibrios were not previously known to use light for food, so this is potentially big news.  His graduate student, Nelson Alves, will be sampling for water-borne viruses by looking for their DNA signature.  These aren’t viruses as we know them (causes of A rhodolith bedhuman disease), but a natural and dominant part of the very smallest members of the plankton, whose importance has only been realized in the last few years.  Gilberto Filho, who is a head botanist at the Botannic Gardens in Rio de Janeiro, talked about the importance of rhodolith beds, which are an unusual sort of habitat made up of softball-sized lumps of reddish rock that are produced by algae that are able to secrete calcium skeletons as they photosynthesise, much like corals do.  These lumps then become substrate for all manner of other things to live on, since they are hard and rigid, unlike the soft, shifting sediments on which they sit.  In this way, rhodoliths can increase the diversity of a patch of otherwise empty seabed.  Ronaldo Francini-Filho talked about what is known and not known about some of the bigger critters that make up the reef community, like fish and larger invertebrates.  The final presentations from National Museum scientist Clovis Castro and student Gustavo concerned deep-sea corals of the Abrolhos, including those that use light and have symbiotic algae in their tissues (zooxanthellate) and those that lack algae and feed by filtering plankton or absorbing organic material directly from seawater (azooxanthellate).  We’ll learn more about each of these projects in coming days, so if you have questions for the researchers, by all means post them in the comments below. 

The hardest part of planning a research trip came next: deciding how on earth we’re going to meet everyone’s needs within a limited timespan, using the assets of the ship and the brain trust of people aboard it.  This is where the beautiful ideality of a proposed sampling scheme meets the stark and sometimes gruesome reality of what you can, practically speaking, actually do.  All scientists, especially biologists, know and dread this bit; indeed, Mmmmm…mesophotic reefs…argleargle….a lot of the very best biologists are those that have mastered this challenging process and can come up with intelligent and efficient sampling schemes that provide maximum bang for the research buck and minimize down or wasted time.  The upside of this process is that as everyone thinks and talks, you start to see the days to come materializing before you, and a sense of very real excitement sets in.  Ahead lie mornings spent deploying the submersible, afternoons sorting samples of sediment, deep sea corals and sponges, and evenings spent measuring water column properties with a CTD/Rosette and ADCP (more on these later).  It’s enough to make any marine scientist practically drool with anticipation. 

Thursday
Jan202011

The start of something beautiful

My travelling partner Kristie Cobb (Georgia AquariumVP) and I arrived in Brazil today for the Abrolhos 2011 expedition.  The flight in from Atlanta is long (10hrs) and a red-eye, so we arrived a little the worse for wear in Rio.  As we flew, I was considering the similarities and differences between Brazil and Australia.  Brazil’s great mountain range is to the west and is immense in both length and height: the Andes.  It circumscribes the Amazon basin, the most spectacular crucible of biodiversity on the planet.  It drains to the eastern seaboard, which has some coral reefs (including the ones we’ll survey), but nothing like the Great Barrier Reef.  By contrast, Australia is mostly a giant flat arid zone (Google the awesomely ominous sounding “yilgarn kraton” to learn more) with its “great” mountain range on the eastern coast, where a once-active subduction zone scraped off enough Pacific sea floor to make a strip of lan on which >75% of Aussies live.  I say “great” because even the highest of the Snowy Mountains is a pimple compared to the Andes.  There are rainforests in appropriate microclimate pockets along the great dividing range, sure, but not like the vast unending ones we flew over today; there just isn’t the volume of reliable rain (recent floods notwithstanding).  Partly as a result of that tiny eastward drainage and low rainfall, the tropical coastal waters of north eastern Australia are nutrient poor and therefore ideal for coral reefs; accordingly, the Great Barrier Reef is the Amazon rainforest of reefs.  They are two countries with priceless biodiversity treasures, of totally different kinds, as dictated by the constraints of their respective geological histories and their prevailing climates.

We came within three miles of the mighty Amazon today; it was just a pity that it was a vertical three miles!

During an awkwardly long layover in Rio de Janeiro, we decided to bail on the airport and make a lightning visit to the famous Christ the Redeemerstatue; a gargantuan art deco edifice that presides over the spectacular sprawl of beachfront hi-rises and mountain-clinging favelasbelow.  I’m really glad we did too, because the views were stunning and the statue itself a marvel; I’m not a religious guy, but you have to admire the inspiration that drives people to conceive of and build such things on that tiny inhospitable peak at the top of Corcovado.

Christ the Redeemer statue, Rio de Janeiro

After that we made our connection to Vitoria, in the state of Espiritu Santu, north of Rio.  Here we will meet up with our Harbor Branch and Brazilian colleagues for a research co-ordination meeting tomorrow; then a short charter flight to meet the R/V Seward Johnsonat our port of departure in Bahia state.  Right now though, it’s caipirinha o’clock!

Monday
Jan172011

Which came first, the Abrolhos or the Abrolhos?

In just a couple of days I’ll join a group of scientists from Brazil, Australia and the US for an expedition to study the reefs of the Abrolhos platform, off Bahia state in Brazil.  When this trip was first mentioned I have to admit being confused.  That’s because, as a native Aussie, to me “the Abrolhos reefs” means a group of reefs and emergent islands off the remote Northwest coast of Western Australia.  So why are there two Abrolhos Reefs, and which came first?

My Brazilian friend and colleague Julia Todorov tells me that Abrolhos is a contraction of two Portuguese words, abro and olhos, meaning “open eyes” as in “Keep your eyes peeled, Marcos, lest you plough the ship into the reef!”.  That etymology is listed in several online sources.  The above Wikipedia link for the Aussie Abrolhos, however, says its not a true etymology, but I don’t see why not, since it applies just as well to reefs as it would to caltrops: basically, watch where you’re going!

Frederick de Houtman (Wikimedia commons)None of that explains why the Aussie reefs got the name, since the Portuguese did not explore Australia that we know of.  Nor does it explain which place name came first.  That’s a bit easier.  The Australian reefs are properly called the “Houtman Abrolhos” or “Frederick de Houtman’s Abrolhos” and were named by de Houtman, the captain of the Dutch East India Company ship Dordrecht in 1619.  He almost certainly named them after the Brazilian reefs, which he had previously sailed through in 1598.  The Brazilian reefs were already known and named at that time, so by name, the Brazilian Abrolhos came first.

Putting the trivialities of human history aside for a moment, we might ask a bigger question: which Abrolhos ultimately came first? Y’know, biologically.  Which reef grew up from the seafloor first?  In short, it was a tie.  Both reefs showed a major growth spurt around 8,000 years ago in the midst of the “last transgression”, when sea level started rising as the ice caps melted away from the last ice age.  This is a pretty common pattern everywhere.  In fact, there are pretty much no extant coral reefs anywhere older than about 12,000 years, since they were all high and dry back then (the reef organisms having receded into what are now much deeper areas).

OK then, if the current reef communities of the Abrolhoses (?) are both about the same age, then which reef came first geologically?  Which one has the longest geological history?  Chalk that one up as a win in the Houtman column.  The current  Houtman Abrolhos islands and reefs sit atop limestone bedrock that is the remnant of a coral reef that grew in the same location in the Quaternary period, before about 125,000 years ago.  The Brazilian Abrolhos, on the other hand, sit atop a layer of flood basalts (i.e. volcanic rocks, solidified lava) that spread out across the edge of the continental shelf during the Eocene (>30 million years ago).  When scientists core into the reef, the oldest reef they find before they hit the volcanic layer is a bit over 7,000 years; suggesting that the Brazilian reefs are relatively much younger (see Dillenburg & Hesp, 2009

The Houtman Abrolhos in Australia. (Wikimedia commons)Aside from the name and the similar recent growth spurt, the Abrolhos reefs have little in common; Houtman Abrolhos is a faily typical Indo-Pacific reef with high coral, invertebrate and fish diversity growing on a relict of an even older reef, whereas Brazilian Abrolhos is species poor and dominated by just a few coral and fish species growing on a volcanic base.  Could the short geological history of the Brazilian Abrolhos account for the biological differences?  Maybe, but biogeography probably has a lot to do with it too.  Houtman Abrolhos are not too far from the Indo-Pacific center of diversity, the highest tropical diversity there is and source of much species richness throughout the Indo-Pacific, whereas Brazilian Abrolhos are remote and cut-off from other major centers of reef diversity.  There will be a lot more to talk about regarding the diversity in Brazilian Abrolhos in future posts.

So the Aussie Abrolhos has probably been around quite a bit longer, but the Brazilian Abrolhos has been known to people (European at least) longer by about 100 years.  Despite this, the Brazilian reefs are still poorly known, having come to research and conservation attention only for the last two decades or so.  Its fantastic to think that on this expedition we will still have so much to learn about such a unique ecosystem.  I look forward to reporting  from onboard the R/V Seward Johnson some new biology in the Brazilian Abrolhos, starting later this week.  I hope you’ll stick around and join in the conversation.

Thursday
Jan132011

Abrolhos, here we come!

Mussismilia braziliensis at the Abrolhos Reefs, BrazilThings have been a little quiet around here over the holiday break, but that’s about to change in a big way.  In just under a week’s time, I’ll be representing Georgia Aquarium in a new international consortium of scientists for an exciting expedition to explore the Abrolhos reef platform off the coast of Brazil from January 20-28.  The Abrolhos are completely unique reefs: they’re the largest and southernmost in the South Atlantic and biologically very different from perhaps more familiar Pacific or Caribbean Reefs.  You’d think they might show some similarity to Caribbean reefs, but not so, possibly because unfavourable currents and the influence of the Amazon pouring into the ocean between the two may serve as an important barrier to animal dispersal (more on that in future posts).  There’s tremendously high endemicity there, which is to say that many of the resident critters are found nowhere else in the world.  Of key importance is the main reef-forming coral Mussismilia braziliensis, a massive species that forms an unusual bommie-like reef structure called a mushroom reef; we’ll meet this species in more detail later too.

The main aim of the expedition is actually to go a bit deeper than the known parts of the Abrolhos, and look at the depths where light starts to get dim: the mesophotic zone.  These parts of many reef platforms are poorly known and nowhere moreso than at Abrolhos, where these areas are completely unexplored.  That’s because mesophotic reefs are beyond comfortable SCUBA diving range and therefore hard to get to.   To study them between 300 and 3,000ft in depth, we’ll be using the Johnson Sea Link, a submersible that operates from the R/V Seward Johnson, which is on a 5 year assignment from it’s home at Harbor Branch Oceanographic Insitute to CEPEMAR, a Brazilian environmental services company.

The Johnson Sea Link and R/V Seward Johnson

There’s much more to come in future blog posts here and in my tweet stream @para_sight or using the hashtag #Abrolhos2011.  We’ll discuss the Abrolhos reefs, mesophotic reefs, some geology and biology, as well as meeting the people and partners and exploring the logistic challenges of making a complex expedition like this happen.  So, I encourage you to follow along and also to share this information with colleagues and (especially) students of marine science so that they might also follow and share in the excitement of discovering new parts of the ocean floor, never seen before, in tropical Brazil.

Sunday
Dec122010

The World's Resilient Reefs

There’s no doubt about it, coral reefs face a lot of threats.  If you watch the news, read the paper or follow online, you might be familiar with many of these: overfishing, nutrient pollution, physical damage from tourists and of course the biggies - diseases, bleaching and ocean acidification.  If you have no idea what I am talking about, read J.E.N. Veron’s piece in Yale Environment 360 for a good introduction, and a thorough demoralisation!  The TL;DR of that article is that bleaching comes from heat stress that causes corals to expel their mutualistic algae, while all that atmospheric carbon dioxide we’re putting up in the air is leading to more acidic oceans that are ever more hostile to corals and other animals that want to deposit a calcium skeleton.  Together, these threats may spell the end of coral reefs as we know them within a generation.  That’s the idea anyway, but to the contrary, I want to make a case here that all is not lost and that efforts to restore reefs are not futile.  I will present two pieces of work that suggest that recovery is possible and can be enhanced if we make a decent effort to help the reef do what it does best - recover - and I want to offer another thought that is very relevant to reef recovery, concerning heterogeneity. 

Black band disease in a massive coralLets start with Caribbean reefs.  What a mess!  All over the Caribbean, reefs have been subjected to widespread damage, especially overharvesting and nutrient pollution, stressors which in turn have been associated with extensive outbreaks of previously unknown diseases.  Why does the Caribbean get it so bad?  Well, there aren’t nearly as many coral species in the West Atlantic as there are in the Indo-West Pacific to start with, i.e. diversity is much lower and so is the percentage of space occupied by corals, or “coral cover”.  So if the key coral species - staghorn Acropora cervicornis and elkhorn A. palmata in particular  - are wiped out, then a lot of the reef forming ability is lost.  With such low diversity, it isn’t far to fall, so to speak.  And that’s exactly what happened.  In some places it was the result of diseases that wiped out sea urchins that would normally graze down algae that would outcompete the corals.  In other places it was overharvesting of herbivorous fishes.  Take away the urchins/fish and the algae runs rampant and overgrows the corals and the reef dies.  To make it worse, we insist on tipping the balance further in favour of algae by adding nutrients in the form of sewage effluent.  A lot of diseases have also taken their toll on Caribbean corals.  Many of these have descriptive names like “brown band”, “black band” and “white pox” that evince the nature of the lesion (say, a discoloured stripe, slowly spreading across the colony); these simplistic descriptions also highlight that their causes are often poorly understood.

So, low diversity, excess nutrients, overharvesting, diseases, pretty hopeless right?  Well, yes, you might think so.  In many parts of the Caribbean, staghorn and elkhorn populations are down >95%.  Let me stress that: coral populations are down by ninety-five percent or more.  How grim is that?  There’s no coming back from that, right?  I mean, that’s too small a population to repopulate, right?  Well, we’ll see in a minute.

A bleached acroporid reefOK, now to the Pacific.  Pacific reefs are like a Rolls Royce to the Caribbean Toyota (see how I did that?  I offended millions of Toyota drivers and all the Caribbean reef fans at the same time - pretty nifty, huh?).  Its undeniable though: on the whole, Pacific reefs have higher diversity, higher coral cover and are just flat out better reefs.  Or rather, they were until the disastrous bleaching event of 1998/99 and those that have occured since.  In addition, with so many more “stony” corals (the reef-forming or scleractinian types), Pacific reefs may be especially susceptible to ocean acidification.  Various folks have tried to predict how the combination of heat/bleaching stress and acidification might affect Pacific reefs; I mentioned Veron’s article earlier, but you could also look at David Bellwoods paper from a couple of years back in Nature.

During the 1998/1999 El Nino event, vast tracts of Pacific reefs were bleached to death.  Areas that had previously had 100% live coral cover now had none, and were soon covered in a veneer of turf algae.  Much like the Caribbean situation, you have to wonder how a reef could possibly recover from that.

Yet - and this is where it gets good - recovery is possible.  Perhaps we shouldn’t be surprised; reefs have had to recover from cyclones, climate changes, diseases and pests since time immemorial.  But, can they recover from the man-made threats we’ve thrown at them lately?  Two people at least say yes.

Ken Nedimyer is an unlikely hero for coral reefs.  A former tropical fish and coral collector for the auqarium biz, he one day realised the threats to both his livelihood and his favourite places, and so he started and now runs runs the Coral Restoration Foundation, a non-profit reef restoration effort based in the Florida Keys.  It seems  like tilting at windmills, but no.  Ken visited Georgia Aquarium recently and explained the foundation’s activities and, crazy as they might seem, it just might work.  Ken and his team have a coral nursery off the coast of Key Largo, where they propagate corals to restore Florida reefs.  How is this possible?  Partly its the power of geometric increase.  If Ken takes a colony of coral and breaks it into 25 pieces, each of those can grow a new colony that within a year or two can be broken into another 25 pieces, or 625 pieces total.  Pretty soon you have enough “frags” or “nubs” to replant a decimated reef.  Ken has done just that and the reefs have shown phenomenal growth since then.  I asked him “What’s the point in replanting a reef if the original insult that killed the reef is still around?”  I thought it was a fair question, but so was his answer, that its like a rainforest thats been clearfelled: the cutting crew is actually long gone but the thing preventing the forest from regrowing is that there aren’t enough seeds left to repopulate.  But, if you plant some new colonies, you can recover the reef and do so suprisingly quickly.  He showed photographic evidence of the reocvery of replanted reefs in just a few short years and by the end, he’d made a believer out of me.  There IS potential for coral propagation as a meaningful way to rehab the reefs of Floirida and the Caribbean.

CRF Coral nursery. Image copyright: Carey Wagner, South Florida Sun Sentinel

What about the vast, vast Pacific though?  How can we possibly restore those reefs?  Enter our second reef scientist, Dr. Bruce Carlson.  Bruce has been a leading figure in coral aquariculture for decades since his seminal works at the Waikiki Aquarium, but he’s also a passionate conservationist, diver and photographer, all of which combined to help him study natural resilience of Pacific reefs.  After the 1998 bleaching event, Bruce had a chance to study the recovery of a number of reefs in Fiji, which he did in collaboration with his wife Marj Awai for the next decade, often on their own dime.  Together they showed that the reef could crash from 100% live cover to just 3% and back to >95% in less than ten years.  In the geological timescale (hell, even the biological), ten years is a fleeting instant.  Thus they showed that reefs can and will recover from disastrous bleaching , naturally.

Bruce Carlson on one of his transects in Fiji. Photo by Marj Awai

The reefs of the world are incredibly special places and we should all be concerned about the threats that they face, but we can’t succumb to fatalism, because if we think that there is no hope, then we will take no action.  To do so would be a terrible mistake because, as Ken Nedimyer and Bruce Carlson show us, passionate and committed people can make a big difference and reefs can heal naturally and do so even better with our help.

Heterogeneity plays an important part in both the decline of reefs and our efforts to rehabilitate them.  In ecological parlance, heterogeneity means “patchiness” and it’s a pervasive feature of studies in biology.  Heterogeneity is important in the problems that reefs suffer: it’s not all reefs everywhere that are degraded, it’s some reefs in some places.  Similarly, our efforts to recover reefs will not occur everywhere reefs do; they will be highly focused in time and especially in space.  Heterogeneity is thus a critical feature of both the problem and the solution.  It means that we must always be mindful of where and when the problems occur, and that we must be equally strategic about applying solutions like Ken’s coral propagation programs.  Given the severity of the problem and the limited resources available to meet the challenge, we have few other choices but we can be confident in the success of our efforts  at preserveing or restoring reefs in at least some places, so that future generations can enjoy them as we have.

 

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!