Ocean Science Archives
Lessons In Coral Reef Survival From Deep Time
Lessons from tens of millions of years ago are pointing to new ways to save and protect today’s coral reefs and their myriad of beautiful and many-hued fishes at a time of huge change in the Earth’s systems.
The complex relationship we see today between fishes and corals developed relatively recently in geological terms – and is a major factor in shielding reef species from extinction, says Professor David Bellwood of the ARC Centre of Excellence for Coral Reef Studies and James Cook University.
The red-breasted Maori-wrasse, Cheilinus fasciatus. Like the butterflyfishes and damselfishes, wrasses have evolved in the presence of coral reefs. The close relationship between corals and fishes has stimulated the speciation of reef fishes and provided them with a sanctuary in difficult times. Photo courtesy of João Paulo Krajewski.
“Our latest research provides strong evidence for a view that today’s coral hotspots are both a refuge for old species and a cradle for new ones,” said Peter Cowman, lead author of a recent report. “This is the first real inkling we’ve had that just protecting a large area of reef may not be enough – you have to protect the right sorts of reef.”
Early coral reefs, 300-400 million years ago were much simpler affairs than today’s colourful and complex systems, Prof. Bellwood says. The fish were not specialised to live on or among corals – either lacking jaws altogether, or else feeding on detritus on the seabed or preying on one another.
“By 200 million years ago we are starting to see fish with jaws capable of feeding on corals, but the real explosion in reef diversity doesn’t occur till about 50 million years ago when we see fishes very like today’s specialist coral feeders emerging.”
It is the ever-increasing complexity of this relationship between corals and fishes over the last 20 or 30 million years that produces the wondrous diversity of today’s reefs, he says. Each has become more critical to the survival of the other as their lives have become more interwoven.
“When people think of coral reefs, they usually think of the beautiful branching corals like staghorn (Acropora) – well the evidence is now fairly clear that Acropora needs certain fish for it to flourish. But, it now appears that this may be a reciprocal relationship with Acropora being important for the evolution and survival of fishes on coral reefs. ”
Unfortunately Acropora corals are highly vulnerable to external impacts like Crown-of-Thorns starfish, coral bleaching, climate change and ocean acidification. Their demise will have far reaching effects on the fishes which interact with them, such as damsels, butterfly fish, cardinals and wrasses.
“The study of the past tells us that reefs are all about relationships and, like a family, for them to survive those relationships need to remain strong,” Peter Cowman said.
“In coming years it is probable reefs will be subject to relentless presses that may cause them to change fundamentally. Those with the best long-term prospects of survival will be the ones where the relationships between fish and corals are healthiest.
Both fish and corals managed somehow to survive the five great mass extinction events of the past, though they sustained massive loss of species. Over time these have left us with a world focus of reef biodiversity centered on the Coral Triangle region to Australia’s north, which in turn helps recharge Australian coral reefs, especially in the west.
“The Coral Triangle is currently subject to intensifying human and ecosystem pressure. The latest work by Peter Cowman and Prof Bellwood suggests it is both a cradle for new species and a refuge in troubled times – so it is vital that it remain intact.
“This isn’t about saving individual species or particular reefs, it’s about maintaining the basic relationships which ensure the survival of the whole,” says Prof Bellwood.
“We’ve had a ‘heads up’ from the past that is giving us fresh insights into what is most important on reefs and why we must protect our precious reefs and fishes into the future.”
Their paper “Coral reefs as drivers of cladogenesis: expanding coral reefs, cryptic extinction events, and the development of biodiversity hotspots” by Peter F. Cowman and David R. Bellwood was published in the Journal of Evolutionary Biology 24: 2543-2562. DOI 10.1111/j.1420-9101.2011.02391.x
The ARC Centre of Excellence for Coral Reef Studies are proud sponsors of the 12th International Coral Reef Symposium, Cairns: 9-13 July 2012.
World's Most Extreme Deep-Sea Vents Revealed: Deeper Than Any Seen Before, And Teeming With New Creatures
Scientists have revealed details of the world's most extreme deep-sea volcanic vents, 5 kilometres down in a rift in the Caribbean seafloor.
The undersea hot springs, which lie 0.8 kilometres deeper than any seen before, may be hotter than 450°C and are shooting a jet of mineral-laden water more than a kilometre into the ocean above.
Despite these extreme conditions, the vents are teeming with thousands of a new species of shrimp that has a light-sensing organ on its back. And having found yet more ‘black smoker’ vents on an undersea mountain nearby, the researchers suggest that deep-sea vents may be more widespread around the world than anyone thought.
Beebe Vent Field Shrimp
Reporting in the scientific journal Nature Communications this week, a team led by marine geochemist Dr Doug Connelly at the National Oceanography Centre in Southampton and marine biologist Dr Jon Copley of the University of Southampton has revealed details of the world's deepest known ‘black smoker’ vents, so-called for the smoky-looking hot fluids that gush from them.
During an expedition in April 2010 aboard the Royal Research Ship James Cook, the scientists used the National Oceanography Centre’s robot submarine called Autosub6000 and a deep-diving vehicle, HyBIS, manufactured by the British firm, Hydro-Lek to locate and study the vents at a depth of five kilometres in the Cayman Trough, an undersea trench south of the Cayman Islands.
The vents, which the team named the Beebe Vent Field after the first scientist to venture into the deep ocean, are gushing hot fluids that are unusually rich in copper, and shooting a jet of mineral-laden water four times higher into the ocean above than other deep-sea vents. Although the scientists were not able to measure the temperature of the vents directly, these two features indicate that the world's deepest known vents may be hotter than 450 ºC, according to the researchers. “These vents may be one of the few places on the planet where we can study reactions between rocks and 'supercritical' fluids at extreme temperatures and pressures,” says Connelly.
The team found a new species of pale shrimp congregating in hordes (up to 2,000 shrimp per m2) around the six-metre tall mineral spires of the vents. Lacking normal eyes, the shrimp instead have a light-sensing organ on their backs, which may help them to navigate in the faint glow of deep-sea vents. The researchers have named the shrimp Rimicaris hybisae, after the deep-sea vehicle that they used to collect them.
The Cayman shrimp is related to a species called Rimicaris exoculata, found at other deep-sea vents 4,000 kilometres away on the Mid-Atlantic Ridge. Elsewhere at the Beebe Vent Field, the team saw hundreds of white-tentacled anemones lining cracks where warm water seeps from the sea bed. “Studying the creatures at these vents, and comparing them with species at other vents around the world; will help us to understand how animals disperse and evolve in the deep ocean,” says Copley.
The researchers also found black smoker vents on the upper slopes of an undersea mountain called Mount Dent. Mount Dent rises nearly three kilometres above the seafloor of the Cayman Trough, but its peak is still more than three kilometres beneath the waves. The mountain formed when a vast slab of rock was twisted up out of the ocean floor by the forces that pull the plates of the Earth's crust apart.
“Finding black smoker vents on Mount Dent was a complete surprise,” says Connelly. “Hot and acidic vents have never been seen in an area like this before, and usually we don’t even look for vents in places like this.” Because undersea mountains like Mount Dent may be quite common in the oceans, the discovery suggests that deep-sea vents might be more widespread around the world than previously thought.
The vents on Mount Dent, which the team has named the Von Damm Vent Field to commemorate the life of geochemist Karen Von Damm, are also thronged with the new species of shrimp, along with snake-like fish, and previously unseen species of snail and a flea-like crustacean called an amphipod. “One of the big mysteries of deep-sea vents is how animals are able to disperse from vent field to vent field, crossing the apparently large distances between them,” says Copley. “But maybe there are more ‘stepping stones’ like these out there than we realised.”
The UK expedition that revealed the vents followed a US expedition in November 2009, which detected the plumes of water from deep-sea vents in the Cayman Trough. A second US expedition is currently using a deep-diving remotely operated vehicle to investigate the vents further and the UK team also plans to return to the Cayman Trough in 2013 with Isis, the National Oceanography Centre’s deep-diving remotely operated vehicle, which can work at depths of up to six kilometres.
The paper ‘Connelly DP, Copley JT et al. (2012). Hydrothermal vent fields and chemosynthetic biota on the world's deepest seafloor spreading centre’ is available from Nature Communications at http://dx.doi.org/10.1038/ncomms1636
Gulf of Mexico Topography Played Key Role in Bacterial Consumption of Deepwater Horizon Spill
Scientists document how geology, biology worked together after oil disaster
When scientist David Valentine and colleagues published results of a study in early 2011 reporting that bacterial blooms had consumed almost all the deepwater methane plumes after the 2010 Gulf of Mexico Deepwater Horizon oil spill, some were skeptical.
How, they asked the University of California at Santa Barbara (UCSB) geochemist, could almost all the gas emitted disappear?
Recovery in June 2010 of water sampling device at the Gulf of Mexico oil spill
Credit: David Valentine
In new results published this week in the journal Proceedings of the National Academy of Sciences (PNAS), Valentine; Igor Mezic, a mechanical engineer at UCSB; and coauthors report that they used an innovative computer model to demonstrate the respective roles of underwater topography, currents and bacteria in the Gulf of Mexico.
This confluence led to the disappearance of methane and other chemicals that spewed from the well after it erupted on April 20, 2010.
The National Science Foundation (NSF) funded the research.
"As scientists continue to peel apart the layers of the Deepwater Horizon microbial story," said Don Rice, director of NSF's chemical oceanography program, "we're learning a great deal about how the ocean's biogeochemical system interacts with petroleum--every day, everywhere, twenty-four/seven. "
The results are an extension of a 2011 study, also funded by NSF, in which Valentine and other researchers explained the role of bacteria in consuming more than 200,000 metric tons of dissolved methane.
"It seemed that we were putting together a lot of pieces," Valentine said. "We would go out, take some samples, and study what was happening in those samples, both during and after the spill.
"There was a transition of the microorganisms and a transition of the biodegradation, and it became clear that we needed to incorporate the movement of the water."
The scientists believed that there was an important component of the physics of the water motion--of where the water went.
Valentine turned to Mezic, who had published results in 2011 forecasting where the oil slick would spread.
"Our work was on the side of: here's where the oil leaked and here's where it went," Mezic said. "We agreed that it would be beautiful if we could put a detailed hydrodynamic model together with a detailed bacterial model."
The resulting computer model has data on the chemical composition of hydrocarbons flowing into the Gulf of Mexico, and is seeded with 52 types of bacteria that consumed the hydrocarbons.
The physical characteristics were based on the U.S. Navy's model of the gulf's ocean currents and on observations of water movements immediately after the spill and for several months after it ended.
The scientists then sought the help of Mezic's former colleagues--engineers at the University of Rijeka in Croatia.
"We needed somebody to build the software," Mezic said. "It was a big task, a mad rush, but they did it.
"The power behind this is a tour de force. A typical study of this kind would take a year, at least. We found a way that led us to answers in three or four months."
The model revealed that one of the key factors in the disappearance of the hydrocarbon plumes was the physical structure of the Gulf of Mexico.
"It's the geography of the gulf," Valentine said. "It's almost like a box canyon. As you go northward, it comes to a head.
"As a result, it's not a river down there; it's more of a bay. And the spill happened in a fairly enclosed area, particularly at the depths where hydrocarbons were dissolving."
When the hydrocarbons were released from the well, bacteria bloomed. In other locations outside the gulf, those blooms would be swept away by prevailing ocean currents.
But in the Gulf of Mexico, they swirled around as if they were in a washing machine, and often circled back over the leaking well, sometimes two or three times.
"What we see is that some of the water that already had been exposed to hydrocarbons at the well and had experienced bacterial blooms, then came back over the well," Valentine said.
"So these waters already had a bacterial community in them, then they got a second input of hydrocarbons."
As the water came back over, he explained, the organisms that had already bloomed and eaten their preferred hydrocarbons immediately attacked and went after certain compounds.
Then they were fed a new influx of hydrocarbons.
"When you have these developed communities coming back over the wellhead, they consume the hydrocarbons much more quickly," Valentine said, "and the bacterial composition and hydrocarbon composition behaves differently. It changes at a different rate than when the waters were first exposed."
The model allowed the scientists to test this hypothesis and to look at some of the factors that had been measured: oxygen deficits and microbial community structure.
"What we found was very good agreement between the two," Valentine said.
"We have about a 70 percent success rate of hitting where those oxygen declines were. It means that not only is the physics model doing a good job of moving the water in the right place, but also that the biology and chemistry results are doing a good job, because you need those to get the oxygen declines. It's really a holistic view of what's going on."
There are valuable lessons to be learned from the study, the scientists believe.
"It tells us that the motion of the water is an important component in determining how rapidly different hydrocarbons are broken down," Valentine said. "It gives us concepts that we can now apply to other situations, if we understand the physics."
Mezic said that this should be a wake-up call for anyone thinking of drilling for oil.
"The general perspective is that we need to pay more attention to where the currents are flowing around the places where we have spills," he said.
"We don't have models for most of those. Why not mandate a model?
"This one worked--three-quarters of the predictions were correct. For almost everything, you can build a model. You build an airplane, you have a model. But you can drill without having a model. It's possible we can predict this. That's what a model is for."
The U.S. Department of Energy and the U.S. Office of Naval Research also supported the research.
In addition to Valentine and Mezic, co-authors of the paper are Senka Macesic, Nelida Crnjaric-Zic, and Stefan Ivic, of the University of Rijeka in Croatia; Patrick J. Hogan of the Naval Research Laboratory; Sophie Loire of the Department of Mechanical Engineering at UCSB; and Vladimir A. Fonoberov of Aimdyn, Inc. of Santa Barbara.
CSA Develops Seabed Restoration Methodology Program
Remediation from organic loading in deepwater marine sediments
CSA International, Inc. (CSA) has initiated a program to develop a remediation methodology that can be successfully utilized with marine sediments that have been subjected to excessive loading with organic compounds, particularly in deepwater environments where biodegradation processes are slowed due to low temperature. To address this problem and in consideration of the inherent difficulties associated with working in deepwater, CSA has combined proven mechanical and biologic technologies to be applied in a unique way.
CSA has assembled the engineering and scientific team to take the program forward and has now completed the Preliminary Design Effort. The concept incorporates proven subsea equipment modified to deploy specific tools developed by the program to properly restore the deepwater seabed through the use of both mechanical and biological systems.
“The capability and capacity advancement of free flying and seabed crawling remotely operated vehicles (ROVs) has finally allowed us to deploy technology to the seabed in a way not previously possible,” stated Kevin Peterson, President and CEO of CSA. “By combining proven ROV tooling technology with the application of known biological compounds, we’re able to positively effect the remediation of marine sediments, speeding up its natural recovery.”
Phase II of the program includes a Pilot Study, during which the efficacy of the prototype will be evaluated in the lab. Phase III will build and test the full size tooling required to be deployed by ROVs of opportunity.
World Ocean Council Invited to Join U.N Secretary General’s Expert Group on Oceans
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Independent Panel to Draft “Oceans Compact” for 10-yearly U.N. Conference on Sustainable Development WOC participation in the U.N. Secretary General’s five-person ocean expert group creates an exceptional opportunity for the ocean business community to help shape international efforts to address ocean sustainability. The oceans have been declared as one of 8 thematic priorities for “Rio + 20” – the U.N. Conference on Sustainable Development taking place in Rio de Janeiro in June 2012. The U.N. Secretary General’s ocean expert group will develop an Oceans Compact for consideration as U.N. input to the conference. In addition to private sector involvement via the WOC Executive Director, the four other experts in the group represent government, academic and non-government organizations. Achim Steiner, U.N. Under-Secretary General and Executive Director of the U.N. Environment Programme (UNEP), said: “The marine environment is under pressure as a result of issues such as over-fishing, insensitive development, pollution and climate change. Engaging the private sector will be an essential element towards ensuring the future health of the oceans and seas. The World Ocean Council (WOC) efforts to catalyze an unprecedented cross-sectoral industry alliance for leadership on ocean sustainability represents an important opportunity to realize this as the world prepares for Rio + 20 in June 2012. Thus I welcome the ocean business community's involvement in this high level UN expert group as a result of the participation of the WOC.” The objective of the Oceans Compact is to build a framework to advance political and pragmatic policies and actions to address the most pressing issues regarding sustainable management of oceans. The compact is to highlight the major challenges facing oceans - such as overfishing, pollution, and the management of ocean ecosystems beyond national jurisdictions - and propose actions to redress these challenges.
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