An international consortium has been formed to study the potential effects of adding iron to the ocean to promote the growth of phytoplankton. Phytoplankton use carbon dioxide from the atmosphere and ocean fertilization might therefore be a way of mitigating the effects of global warming. When phytoplankton die, organic carbon sinks to the seafloor where it may remain for decades, centuries or even longer – we still do not now much about the time-line.

Iron fertilization of the ocean is far from uncontroversial, since it is very difficult to foresee the long term effects of such a project. The international consortium, which has been named In-Situ Iron Studies (ISIS) consortium , will carry out iron fertilization experiments in the open ocean in an effort in to answer some of the questions regarding how iron affects the ocean’s capacity for dragging carbon dioxide from the air and into the water. All experiments will adhere to the London Convention/London Protocol regarding ocean iron fertilization research.

“A great deal remains to be learned about ocean iron fertilization and how effective it could be in storing carbon dioxide in the oceans, and the formation of this consortium is an important first step,” says Lewis Rothstein, professor of oceanography at the University of Rhode Island. “This is not a call for climate engineering; on the contrary this is a research consortium. It is premature to advocate for large-scale ocean iron fertilization, but it is time to conduct a focused research experiment that will examine the concept as comprehensively as we can. We want to make sure that it doesn’t generate harmful side effects that might negatively affect the marine ecosystem.”

The twelve ISIS-members are the following:
University of Rhode Island, USA
University of Hawaii, USA
University of Illinois at Urbana-Champaign, USA
University of Maine, USA
University of Massachusetts Boston, USA
University of Plymouth, UK
Xiamen University, Fujian, China
The Antarctic Climate and Ecosystems Cooperative Research Centre, Australia
Netherlands Institute for Sea Research, The Netherlands
The National Oceanography Centre, UK
Moss Landing Marine Laboratories, California, USA
Woods Hole Oceanographic Institution, Massachusetts, USA

Dr Parker, from James Cook University’s School of Veterinary and Biomedical Sciences, and collaborator Professor Rocky de Nys, from JCU’s School of Marine and Tropical Biology, have just received a $7,000 Collaboration Across Boundaries grant to prove their theory that feeding seaweed to cow will improve their digestion and make them produce less methane.

Just like carbon dioxide, methane is a so called green-house gas and the world’s cattle population accounts for up to 20% of methane emissions from human-related activities. Global warming is suspected to be one of several factors harming our tropical reefs worldwide and finding ways of reducing the amount of methane released into the air is therefore highly interesting.

Dr Parker and Professor Rocky de Nys will now test their theory on herd of cattle living at the University’s Townsville campus.

“Orkney sheep are ruminants that live off seaweed and they do very well on such a diet; so the obvious question is, why can’t cows?” said Dr Parker.

“I like to call it the reef and beef project because it has far reaching implications that come full circle:starting with seaweed, taking in the beef and aquaculture industries, and extending back out to the sea to help conserve the Great Barrier Reef.”

“The ‘underwater turbulence’ the jellies create is being debated as a major player in ocean energy budgets,” says marine scientist John Dabiri of the California Institute of Technology.

Jellyfish are often seen to be aimless aquatic drifters, propelled by nothing but haphazard currents and waves, but the truth is that these gooey creatures continuously contract and relax their bells to move in desired directions.

The jellyfish Mastigias papua carries algae-like zooxanthellae within its tissues from which it derives energy and since the zooxanthellae depend on photosynthesis, the jellyfish has to stay in sunny locations. Research carried out in the so called Jellyfish Lake, located in the island nation of Palau 550 miles east of the Philippines, shows that this jellyfish doesn’t rely on currents to bring it to sunny spots – it willingly budges through the lake as the sun moves across the sky.

In Jellyfish Lake, enormous congregations of Mastigias papua can be found in the western half of the lake each morning, eagerly awaiting dawn. As the sun rises in the east, all jellyfish turn towards it and starts swimming towards east. The smarmy creatures will swim for several hours until they draw near the eastern end of the lake. They will however never reach the eastern shore, since the shadows cast by trees growing along the shoreline cause them to stop swimming. They shun the shadows and will therefore come to a halt in the now sundrenched eastern part of the lake. As the solar cycle reverses later in the afternoon, millions of jellyfish will leave the eastern part of the lake and commence their journey back to the western shore.

Together with his research partner, marine scientists Michael Dawson of the University of California at Merced, John Dabiri have investigated how this daily migration of millions of jellyfish affects the ecosystem of the lake.

What the jellies are doing, says Dabiri, is “biomixing”. As they swim, their body motion efficiently churns the waters and nutrients of the lake.

Dabiri and Dawson are exploring whether biomixing could be responsible for an important part of how ocean, sea and lake waters form so called eddies. Eddies are circular currents responsible for bringing nitrogen, carbon and other elements from one part of a water body to another. The two researchers have already shown how Jellyfish like Mastigias papua and the moon jelly Aurelia aurita use body motion to generate water flow that transports small copepods within jellyfish feeding range; now they want to see if jellyfish movements make any impact on a larger scale.

“Biomixing may be a form of ‘ecosystem engineering’ by jellyfish, and a major contributor to carbon sequestration, especially in semi-enclosed coastal waters,” says Dawson.

According to the simplest version of the so called Iron Hypothesis, plankton blooms move atmospheric carbon down to the deep sea and increased carbon dioxide levels in the atmosphere can therefore be counteracted by promoting plankton blooms. The Iron Hypothesis derives its names from the suggestion that global warming can be thwarted by fertilizing plankton with iron in regions that are iron-poor but rich in other nutrients like nitrogen, silicon, and phosphorus, such as the Southern Ocean.

New research from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory is now dealing a powerful blow to this hypothesis by showing that most of the carbon used for plankton blooms never reaches to deep sea.

Using data collected around the clock for over a year by deep-diving Carbon Explorer floats, Oceanographers Jim Bishop* and Todd Wood** have revealed that a lot of the carbon tied up by plankton blooms never sink very far.

“Just adding iron to the ocean hasn’t been demonstrated as a good plan for storing atmospheric carbon,” says Bishop. “What counts is the carbon that reaches the deep sea, and a lot of the carbon tied up in plankton blooms appear not to sink very fast or very far.”

The reasons behind this behaviour are complex, but the seasonal feeding behaviour of planktonic animal life is believed to play major part.

Photoplankton

The Carbon Explorer floats used in the study were launched in January 2002, as a part of the Southern Ocean Iron Experiment (SOFeX)***, and experiment meant to test the Iron Hypothesis in the waters between New Zealand and Antarctica during the Antarctic summer.

SOFeX fertilized and measured two regions of ocean, one in an HNLC (high-nutrient, low-chlorophyl) region at latitude 55 degrees south and another at 66 degrees south. Carbon Explorers were launched at both these sites while a third Carbon Explorer was launched well outside the iron-fertilized region at 55 degrees south as a control.

Bishop and Wood were originally assigned to the project to monitor the iron-fertilization experiment for 60 days, but the Carbon Explorers continued to transmit data throughout the Antarctic fall and winter and on into the following spring.

“We would never have made these surprising observations if the autonomous Carbon Explorer floats hadn’t been recording data 24 hours a day, seven days a week, at depths down to 800 meters or more, for over a year after the experiment’s original iron signature had disappeared,” Bishop explains. “Assumptions about the biological pump – the way ocean life circulates carbon – are mostly based on averaging measurements that have been made from ships, at intervals widely separated in time. Cost, not to mention the environment, would have made continuous ship-based observations impossible in this case. Luckily one Carbon Explorer float costs only about as much as a single day of ship time.”

The scientific hypothesis that iron can be used to stimulate phytoplankton growth in regions low in iron but rich in other nutrients is still intact and experiments show that algal blooms do in fact occur if you add iron to such waters. The study by Bishop and Wood only shows that the carbon bound by the plankton do not end up far down in the depths of the sea.

Jim Bishop’s team. (From left) Christopher Guay,
Phoebe Lam, Jim Bishop, Todd Wood, and David Kaszuba.

During the early stages of the South Sea experiment, the Iron Hypothesis seemed to hold up to scrutiny as the Berkeley researchers could detect not only a vigorous plankton bloom in the fertilized region at 55°N, but also how carbon particles sank beneath the bloom carrying 10-20 percent of the fixed carbon away from the surface layer and down to a dept of at least 100 meters. These results were published in the 2004April issue of Science.

But since the Carbon Explorers continued to submit information even when the 3-month study was officially over, Bishop and Wood could continue their monitoring of South Sea carbon levels throughout fall and winter and well into the following spring; a continued monitoring that would prove invaluable.

The two Carbon Explorers released at 55 degrees south continued to report for over 14 months and almost reached South America before they turned silent. After this, the explorer launched at 66 degrees south continued to transmit for another four months, despite having spent much of the Arctic winter recording at a dept of 800 meters where the pressure is immense. This explorer also had several encounters with the underside of chunky sea ice as it tried to surface to report during the Arctic winter.

All this new data surprisingly showed that there seemed to be much less particulate matter reaching the depth where the biomass was highest, i.e. in plankton blooms. Reports from the 66°S explorer showed how particulate carbon levels decreased sharply as the perpetually dark Arctic winter commenced and ice began to cover previously open waters. As the sun returned in spring and melted the ice the levels made a modest increase, but no sinking (sedimentation) of large amounts of carbon to the deep ocean was observed.

Another even more surprising report came from the control float, dubbed 55 C, which reported higher sedimentation of carbon 800 meters under a region with no plankton bloom than what the other 55°S (dubbed 55A) reported from the fertilized, blooming region.

Researchers are currently pondering several ideas as to explain these unforeseen results but have not reached any conclusion. A higher biomass seems to be linked to a lower export of carbon, but one knows why. One of the most promising hypotheses takes into account how phytoplankton needs sufficient amounts of light to survive and grow. Latitude 55°S is located far enough from the Arctic for light to reach the ocean year round, even though the amount is severely reduced during the winter months. But the notorious winter storms occurring in these waters can cause mixing between near-surface water and underlying water layers all the way down to a dept of 400-500 meters. Phytoplankton are dragged down to depths where it is too dark for them to grow and where hungry zooplankton waits for them.

“Mixing is the dumbwaiter that brings food down,” says Bishop. “The question is whether the dumbwaiter is empty or full.”

If mixing is consistently below the critical light level, phytoplankton can not grow, i.e. the dumbwaiter stays empty and the zooplankton gets no food. As the winter storms stop with the advent of spring, the phytoplankton can quickly rebound, aided by increased levels of sunlight. But since a lot of zooplankton starved to death during the winter, the zooplankton population is not large enough to keep steps with the phytoplankton bloom and intercept carbon loaded material as it sinks between 100 and 800 meters.

In the part of the South Sea where Carbon Explorer 55C spent the winter collecting data, storms where not continuous and the mixing was therefore halted now and then. More zooplankton survived, zooplankton which fed on the phytoplankton in spring, keeping their numbers down and increasing carbon sedimentation.

Bishop says these observations point to an important lesson: “Iron is not the only factor that

determines phytoplankton growth in HNLC regions. Light, mixing, and hungry zooplankton are fundamentally as important as iron.”

You can find more information about Bishop and Wood’s study in the journal Global Biogeochemical Cycles. Preprints of the issue are already available to subscribers at http://www.agu.org/journals/gb/papersinpress.shtml.

* Jim Bishop is a member of Berkeley Lab’s Earth Sciences Division and a professor of Earth and planetary sciences at the University of California at Berkeley.

** Todd Wood is a staff researcher with the U.S. Department of Energy’s Laurence Berkley National Laboratory.

*** The Southern Ocean Iron Experiment (SOFeX) is a collaboration led by scientists from Moss Landing Marine Laboratory and the Monterey Bay Aquarium Research Institute.

In a study announced today by the Wildlife Conservation Society* (WCS) at the International Coral Reef Initiative** (ICRI) meeting in Thailand, researchers show that some coral reefs located off East Africa are unusually resilient to climate change. The high resilience is believed to be caused by geophysical factors in combination with improved fisheries management in these waters.

After studying corals off the coast of Tanzania, researchers found that these coral reefs has made an incredibly speedy recovery from the 1998 bleaching event that wiped out up to 45 percent of the region’s corals. The authors of the study attribute the swift recovery to a combination of reef structure and reef management.

Compared to many other coral reefs around the world, Tanzania’s reefs are used to considerable variations in both current and water temperature which has turned these reefs into an unusually complex web of different coral species. This bio-diverse ecosystem includes several different species known to quickly re-colonize an area after a bleaching incident.

The authors of the study believe that reefs in other parts of the world subjected to similarly diverse environmental conditions might have the same high ability to recover from large-scale climatic and human disturbances. The study provides additional evidence that such “super reefs” can be found in the triangle from Northern Madagascar across to northern Mozambique to southern Kenya and the authors suggest that these reefs should be a high priority for conservation efforts since they may come to play an important global role in the future recovery of coral reefs worldwide.

“Northern Tanzania’s reefs have exhibited considerable resilience and in some cases improvements in reef conditions despite heavy pressure from climate change impacts and overfishing,” says Dr. Tim McClanahan***, the study’s lead author. “This gives cause for considerably more optimism that developing countries, such as Tanzania, can effectively manage their reefs in the face of climate change.”

The study also stresses the impact of direct management measures in Tanzania, including closures to commercial fishing. Algae is known to easily smother corals, but researchers found how areas with fishery closures contained a rich profusion of algae eating fish species that kept the corals clean. The few sites without any management measures remained degraded, and in one of them the population of sea urchins had exploded. Sea urchins feed on corals and can therefore worsen the problem for an already suffering reef.

The study has been published in the online journal Aquatic Conservation: Marine and Freshwater Ecosystems.

Authors of the study include Tim McClanahan and Nyawira Muthiga of the Wildlife Conservation Society, Joseph Maina of the Coral Reef Conservation Project, Albogast Kamukuru of the University of Dar es Salaam’s Department of Fisheries Science and Aquaculture, and Saleh A.S. Yahna of the University of Dar es Salaam’s Institute of Marine Sciences and Stockholm University’s Department of Zoology.

* The Wildlife Conservation Society is an institutional partner to ICRI and is actively conserving tropical coral reef species in priority seascapes in Belize, Indonesia, Papua New Guinea, Fiji, Kenya and Madagascar. Along with monitoring reefs, WCS also trains of park staff in protected areas.

** The International Coral Reef Initiative (ICRI) is a global partnership among governments and organizations working to stop and reverse the degradation of coral reefs and related ecosystems. This ICRI General Meeting was convened by the joint Mexico – United States Secretariat.

*** Dr. McClanahan’s research regarding ecology, fisheries, climate change effects, and management of coral reefs at key sites throughout the world is supported by the Western Indian Ocean Marine Science Association (WIOMSA) and The Tiffany & Co. Foundation.

The oceans of the world absorb a large part of the carbon dioxide released into the atmosphere by us burning fossil fuels, burning forests to make room for fields, etc. This have helped slow down global warming, but new studies shows that it might have a devastating effects on certain fish species such as clown fish. Tests performed on clown fish larvae have shown that increased levels of carbon dioxide can make them disoriented an unable to find a suitable home and avoid predators. The pH level in the ocean has dropped 0.1 since pre-industrial times due to the absorption of carbon dioxide and researchers believe that it will fall another 0.3-0.4 before the end of this century.

This increased acidicy of the water can cause serious problems for clown fish larvae, since clownfish larvae lose the ability to sense vital odours in more acidic waters – probably owing to the damage caused to their olfactory systems. Kjell Døving (Oslo University), co-author of the rapport that was published in US journal Proceedings of the National Academy of Sciences, says “They can’t distinguish between their own parents and other fish, and they become attracted to substances they previously avoided. It means the larvae will have less opportunity to find the right habitat, which could be devastating for their populations.“

The research indicates that other species might be affected in a similar way and might have a hard time finding their way to suitable habitats if carbon dioxide levels raises in the oceans.

About the study

The study was executed in such a way that the researchers checked how well clownfish larvae could detect smells in normal sea water (pH 8.15) and how well they could detect odours in more acidic water (at levels predicted to be a reality around the year 2100 and later). The test showed that at pH 7.8 the larvae stopped following scent trails released by reefs and anemones and started following sent trails they would normally avoid; scents that are associated with environments not suitable for clown fish. The larvae also lost the ability to use smell to distinguish between their parents and other fish. At pH 7.6 the larvae were unable to follow any kind of odour in the water, and instead swam in random directions.

Vast amounts of creatures looking like jelly balls have begun to appear off the eastern coast of Australia, and researchers now suspect that these animals may help slow down global warming by moving carbon dioxide from the atmosphere to the ocean floor.

The proper English name for this “jelly ball” being is salp. A salp is a barrel-shaped free-floating tunicate that moves around in the ocean by contracting and relaxing its gelatinous body. Just like the other tunicates, the salp is a filter feeder that loves to eat phytoplankton and this is why it has caught the attention of scientists researching global warming.

Phytoplankton are famous for their ability to absorb carbon dioxide from the top level of the sea, and a salp feasting on phytoplankton will excrete that carbon dioxide in the form of faeces. The faeces will drop to the ocean floor; thus lowering the amount of carbon dioxide present in the upper part of the ocean. Since the carbon dioxide found in this level of the sea chiefly hails from the atmosphere, phytoplankton and salps are a great aid when it comes to removing carbon dioxide from the air. Salps will also bring carbon down to the ocean floor when they die, which happens fairly often since the life cycle of this organism is no more than a few weeks.

Salp species can be found in marine environments all over the world, but they are most abundant and concentrated in the Southern Ocean near Antarctica where it is possible to encounter enormous swarms of salp. Over the last 100 years, krill populations in the Southern Ocean have declined and salp populations seem to be replacing them in this cold ecosystem. According to researcher Mark Baird of the Australian Commonwealth Scientific and Research Organization (CSIRO), the amount of salps in the waters off Australia are also on the increase, at least according to a survey carried out last month by CSIRO and the University of New South Wales.

While salp may help slow down global warming, their increase may also cause problems. Salp has a fairly low nutrient content and salps replacing nutrient rich krill in the Southern Sea may therefore prove detrimental for oceanic animals higher up in the food chain.

According to University of Queensland marine biologist Professor Ove Hoegh-Guldberg, recipient of the prestigious Eureka science prize in 1999 for his work on coral bleaching, sea temperatures are likely to rise 2 degrees C over the next three decades due to climate change and such an increase will cause Australia’s Great Barrier Reef to die.

Hoegh-Guldberg’s statement is now being criticized by other scientists for being overly pessimistic, since it does not consider the adaptive capabilities of coral reefs. According to Andrew Baird, principal research fellow at the Australian Research Council’s Centre for Excellence for Coral Reef Studies, there are serious knowledge gaps when it comes to predicting how rising sea temperatures would affect the coral.

Great barrier reef

“Ove is very dismissive of coral’s ability to adapt, to respond in an evolutionary manner to climate change,” says Dr Baird. “I believe coral has an underappreciated capacity to evolve. It’s one of the biological laws that, wherever you look, organisms have adapted to radical changes.”

According to Dr Baird, climate change would result in major alterations of the reef, but not necessarily death since the adaptive qualities of coral reefs would mitigate the effects of an increased water temperature. “There will be sweeping changes in the relative abundance of species,” he says. “There’ll be changes in what species occur where. But wholesale destruction of reefs? I think that’s overly pessimistic.”

Marine scientist Dr Russell Reichelt, chairman of the Great Barrier Reef Marine Park Authority, agrees with Dr Baird. “I think that he’s right,” says Dr Reichelt. “The reef is more adaptable and research is coming out now to show adaptation is possible for the reef.”

Professor Hoegh-Guldberg responds to the criticism by saying that the view “that reefs somehow have some magical adaptation ability” is unfounded. He also raises the question of how big of a risk we are willing to take. “The other thing is, are we willing to take the risk, given we’ve got a more than 50 per cent likelihood that these scenarios are going to come up?” professor Hoegh-Guldberg asks.”If I asked (my colleagues) to get into my car and I told them it was more than 50 per cent likely to crash, I don’t think they’d be very sensible getting in it.“

As we release more and more carbon dioxide from fossil fuel into the atmosphere, the world’s oceans become more and more acidic. Exactly how this will affect marine life remains unknown, but a paper published this week by marine chemists Keith Hester and his co-authors at the Monterey Bay Aquarium Research Institute is now shedding some light on how a change in acidity affects sound waves under water.

Beluga Whale

So, why is the speed of sound underwater of any interest to Monterey Bay Aquarium researchers? As sounds travel faster, the amount of background noise in the sea will increase and this could affect the behaviour of marine mammals. Many marine mammals, such as whales, dolphins, and porpoises, relay on sounds for communication and food location.

According to conservative projections by the Intergovernmental Panel on Climate Change (IPCC), the chemistry of seawater could change by 0.3 pH units by 2050. According to Hester and his colleges, such a change in acidity would allow sounds to travel up to 70 percent farther underwater in some areas, especially in the Atlantic Ocean. The paper also states that sound may already be travelling 10 percent farther in the oceans than it did a few centuries ago.

According to Hester et al, a change by 0.3 pH units by 2050 will have the greatest effect on sounds below about 3,000 cycles per second. This range includes most of the low frequency sounds that marine mammals are known to use, but it also includes a lot of sounds produced by human activity, such as boating, shipping, and certain military activities. As if acidification of the ocean wasn’t enough, the amount of underwater sound produced by human activities has increased dramatically over the last 50 years. So, even if acidification would make it possible for sound produced by marine mammals to travel farther than ever before, it might also cause these sounds to be effectively drenched by a cacophony of human generated low frequency noise. In such a noisy sea, a marine mammal’s ability to locate prey animals and a suitable mate and could be severely impinged on.

The paper will be published in the October 1, 2008 issue of Geophysical Research Letters.

Tidal movements involve immense amounts of energy and are as reliable as, well, the tide. If we could find an efficient way of harnessing these mammoth forces, tidal action might become an important source of renewable energy for populations world wide. With this in mind, a team of engineers from Oxford University have worked together to develop a new and more robust turbine design that will make it both easier and more cost-effective to take advantage of this natural resource.

The turbines developed by the research team have been labelled “second generation” tidal turbines since they are less expensive to build and maintain compared to traditional tidal turbines, and capable of harnessing more energy. Unlike today’s underwater turbines – which are built like underwater windmills with blades that turn at right angles to the flow of water – these second generation tidal turbines are centred on a cylindrical rotor which rolls around its long axis as the water ebbs and flows. The Oxford team calls their new creation Thawt, short for Transverse Horizontal Axis Water Turbine.

Producing enough energy for 12,000 average UK family homes using traditional turbine design would today require 10 generators and five foundations. With the new Thawt, only one generator and three foundations would be enough, according to estimates done by the Oxford team.

Steph Merry, head of marine renewable energy at the Renewable Energy Association welcomed the new design but also cautioned against the costs of environmental monitoring to safeguard the ecology of tidal areas. “We have to get it in proportion, you can’t have an unlimited budget for environmental monitoring when every engineering company has to work to a budget for any project. At the moment, there is no limit to the monitoring that can be imposed.”