Climate change will upset vital ocean chemical cycles, research shows

Sep. 8, 2013 — New research from the University of East Anglia shows that rising ocean temperatures will upset natural cycles of carbon dioxide, nitrogen and phosphorus.Plankton plays an important role in the ocean’s carbon cycle by removing half of all CO2 from the atmosphere during photosynthesis and storing it deep under the sea — isolated from the atmosphere for centuries.Findings published today in the journal Nature Climate Change reveal that water temperature has a direct impact on maintaining the delicate plankton ecosystem of our oceans.The new research means that ocean warming will impact plankton, and in turn drive a vicious cycle of climate change.Researchers from UEA’s School of Environmental Sciences and the School of Computing Sciences investigated phytoplankton — microscopic plant-like organisms that rely on photosynthesis to reproduce and grow.Lead researcher Dr Thomas Mock, said: “Phytoplankton, including micro-algae, are responsible for half of the carbon dioxide that is naturally removed from the atmosphere. As well as being vital to climate control, it also creates enough oxygen for every other breath we take, and forms the base of the food chain for fisheries so it is incredibly important for food security.”Previous studies have shown that phytoplankton communities respond to global warming by changes in diversity and productivity. But with our study we show that warmer temperatures directly impact the chemical cycles in plankton, which has not been shown before.”Collaborators from the University of Exeter, who are co-authors of this study, developed computer generated models to create a global ecosystem model that took into account world ocean temperatures, 1.5 million plankton DNA sequences taken from samples, and biochemical data.”We found that temperature plays a critical role in driving the cycling of chemicals in marine micro-algae. It affects these reactions as much as nutrients and light, which was not known before,” said Dr Mock.”Under warmer temperatures, marine micro-algae do not seem to produce as many ribosomes as under lower temperatures. Ribosomes join up the building blocks of proteins in cells. They are rich in phosphorus and if they are being reduced, this will produce higher ratios of nitrogen compared to phosphorus, increasing the demand for nitrogen in the oceans.”This will eventually lead to a greater prevalence of blue-green algae called cyanobacteria which fix atmospheric nitrogen,” he added.

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Climate change will upset vital ocean chemical cycles

Sep. 8, 2013 — New research from the University of East Anglia shows that rising ocean temperatures will upset natural cycles of carbon dioxide, nitrogen and phosphorus.Plankton plays an important role in the ocean’s carbon cycle by removing half of all CO2 from the atmosphere during photosynthesis and storing it deep under the sea — isolated from the atmosphere for centuries.Findings published today in the journal Nature Climate Change reveal that water temperature has a direct impact on maintaining the delicate plankton ecosystem of our oceans.The new research means that ocean warming will impact plankton, and in turn drive a vicious cycle of climate change.Researchers from UEA’s School of Environmental Sciences and the School of Computing Sciences investigated phytoplankton — microscopic plant-like organisms that rely on photosynthesis to reproduce and grow.Lead researcher Dr Thomas Mock, said: “Phytoplankton, including micro-algae, are responsible for half of the carbon dioxide that is naturally removed from the atmosphere. As well as being vital to climate control, it also creates enough oxygen for every other breath we take, and forms the base of the food chain for fisheries so it is incredibly important for food security.”Previous studies have shown that phytoplankton communities respond to global warming by changes in diversity and productivity. But with our study we show that warmer temperatures directly impact the chemical cycles in plankton, which has not been shown before.”Collaborators from the University of Exeter, who are co-authors of this study, developed computer generated models to create a global ecosystem model that took into account world ocean temperatures, 1.5 million plankton DNA sequences taken from samples, and biochemical data.”We found that temperature plays a critical role in driving the cycling of chemicals in marine micro-algae. It affects these reactions as much as nutrients and light, which was not known before,” said Dr Mock.”Under warmer temperatures, marine micro-algae do not seem to produce as many ribosomes as under lower temperatures. Ribosomes join up the building blocks of proteins in cells. They are rich in phosphorus and if they are being reduced, this will produce higher ratios of nitrogen compared to phosphorus, increasing the demand for nitrogen in the oceans.”This will eventually lead to a greater prevalence of blue-green algae called cyanobacteria which fix atmospheric nitrogen,” he added.

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First global atlas of marine plankton reveals remarkable underwater world

July 19, 2013 — Under the microscope, they look like they could be from another planet, but these microscopic organisms inhabit the depths of our oceans in nearly infinite numbers.To begin to identify where, when, and how much oceanic plankton can be found around the globe, a group of international researchers have compiled the first ever global atlas cataloguing marine plankton ranging in size from bacteria to jellyfish. The atlas was published today in a special issue of the journal Earth System Science Data.The atlas, known as the Marine Ecosystem Biomass Data (MAREDAT), is the first step towards a comprehensive inventory of the marine biota based on counts of individual cells or organisms. It will help researchers better understand marine biodiversity for conservation and monitoring and is the result of collaborations between scientists at the Woods Hole Oceanographic Institution (WHOI), the University of East Anglia, ETH Zurich, University of Manchester, Université d’Angers and CNRS, the US National Oceanic and Atmospheric Administration (NOAA), together with many other scientific institutions around the world.”One of the more surprising findings from the study is that phytoplankton and zooplankton biomass are roughly the same size in the upper ocean. Compare that to more familiar land ecosystems where the biomass of plants greatly exceeds that of animals and it’s pretty illuminating,” says WHOI Senior Scientist and Marine Chemist Scott Doney, a collaborator on the project.The MAREDAT database is open-source and available through a public website.Thus far, it has catalogued about half a million measurements of plankton biomass, which are subdivided into 12 broad plankton groups. Each group has a separate database.”The data and documentation can be downloaded by any researcher so that they can explore their own scientific questions,” Doney says. “Over time we hope to grow the database by adding other historical and newly collected data for plankton groups already in the database as well as extend into different plankton groups.”One group of microorganisms Doney and his colleague Yawei Luo have focused on cataloguing in MAREDAT is marine nitrogen-fixing bacteria called “diazotrophs.” These unique microbes can literally make the nutrients they need for growth out of thin air, or at least from dissolved nitrogen gas. They play an essential role in subtropical ocean gyres providing a source of nitrogen in the otherwise nutrient-poor surface waters. The nitrogen fixation rates and diazotroph cell counts are being used to study the environmental conditions that determine nitrogen fixation and diazotroph community structure.Working with more than 45 other scientists from WHOI and around the world, Luo and Doney built the first-ever global dataset on nitrogen-fixers by collecting data from historical scientific literature and existing databases. The past decade has seen a virtual explosion in new ocean field data on marine nitrogen-fixers spanning a wide range of taxonomic groups including free-living cells and filamentous organisms as well as symbiotic organisms that live inside other plankton. Luo and Doney study ocean microbes as part of the Center for Microbial Oceanography, Research, and Education (C-MORE), a National Science Foundation Science and Technology Center based at the University of Hawaii.The first edition of the MAREDAT global plankton atlas took three years to compile and combines information from half a million data points. …

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New study proposes solution to long-running debate as to how stable the Earth system is

June 10, 2013 — Researchers at the University of Southampton have proposed an answer to the long-running debate as to how stable the Earth system is.Earth, with its core-driven magnetic field, oceans of liquid water, dynamic climate and abundant life is arguably the most complex system in the known Universe. Life arose on Earth over three and a half billion years ago and it would appear that despite planetary scale calamities such as the impacts of massive meteorites, runaway climate change and increases in brightness of the Sun, it has continued to grow, reproduce and evolve ever since.Has life on Earth simply been lucky in withstanding these events or are there any self-stabilising processes operating in the Earth system that would reduce the severity of such perturbations? If such planetary processes exist, to what extent are they the result of the actions of life?Forty years ago James Lovelock formulated his Gaia Hypothesis in which life controls aspects of the planet and in doing so maintains conditions that are suitable for widespread life despite shocks and perturbations. This hypothesis was and remains controversial in part because there is no understood mechanism by which such a planetary self-stabilising system could emerge.In research published in PLOS Computational Biology, University of Southampton lecturer Dr James Dyke and PhD student Iain Weaver detail a mechanism that shows how when life is both affected by and alters environmental conditions, then what emerges is a control system that stabilises environmental conditions. This control system was first described around the middle of the 20th Century during the development of the cybernetics movement and has until now been largely neglected. Their findings are in principle applicable to a wide range of real world systems — from microbial mats to aquatic ecosystems up to and including the entire biosphere.Dr Dyke says: “As well as being a fascinating issue in its own right, we quite desperately need to understand what is currently happening to Earth and in particular the impacts of our own behaviour.”Pretty much whatever we do, life on Earth will carry on, just as it did for the previous 3.5 billion years or so. It is only by discovering the mechanisms by which our living planet has evolved in the past can we hope to continue to be part of its future.”

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Cooling ocean temperature could buy more time for coral reefs

May 14, 2013 — Limiting the amount of warming experienced by the world’s oceans in the future could buy some time for tropical coral reefs, say researchers from the University of Bristol.

The study, published by the journal Geophysical Research Letters, used computer models to investigate how shallow-water tropical coral reef habitats may respond to climate change over the coming decades.

Elena Couce and colleagues found that restricting greenhouse warming to three watts per square metre (equivalent to just 50-100 parts per million carbon dioxide, or approximately half again the increase since the Industrial Revolution) is needed in order to avoid large-scale reductions in reef habitat occurring in the future.

Shallow-water tropical coral reefs are amongst the most productive and diverse ecosystems on the planet. They are currently in decline due to increasing frequency of bleaching events, linked to rising temperatures and fossil fuel emissions.

Elena Couce said: “If sea surface temperatures continue to rise, our models predict a large habitat collapse in the tropical western Pacific which would affect some of the most biodiverse coral reefs in the world. To protect shallow-water tropical coral reefs, the warming experienced by the world’s oceans needs to be limited.”

The researchers modelled whether artificial means of limiting global temperatures — known as solar radiation ‘geoengineering’ — could help. Their results suggest that if geoengineering could be successfully deployed then the decline of suitable habitats for tropical coral reefs could be slowed. They found, however, that over-engineering the climate could actually be detrimental as tropical corals do not favour overly-cool conditions. Solar radiation geoengineering also leaves unchecked a carbon dioxide problem known as ‘ocean acidification’.

Elena Couce said: “The use of geoengineering technologies cannot safeguard coral habitat long term because ocean acidification will continue unabated. Decreasing the amount of carbon dioxide in the atmosphere is the only way to address reef decline caused by ocean acidification.”

Dr Erica Hendy, one of the co-authors, added: “This is the first attempt to model the consequences of using solar radiation geoengineering on a marine ecosystem. There are many dangers associated with deliberate human interventions in the climate system and a lot more work is needed to fully appreciate the consequences of intervening in this way.”

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Why we need to put the fish back into fisheries

May 19, 2013 — Overfishing has reduced fish populations and biodiversity across much of the world’s oceans. In response, fisheries are increasingly reliant on a handful of highly valuable shellfish. However, new research by the University of York shows this approach to be extremely risky.

The research, published today in the journal Fish and Fisheries, shows that traditional fisheries targeting large predators such as cod and haddock, have declined over the past hundred years. In their place, catches of shellfish such as prawns, scallops and lobsters have rocketed as they begin to thrive in unnaturally predator-low environments often degraded by the passage of trawls and dredges.

In many places, including the UK, shellfish are now the most valuable marine resource. The research by the Environment Department at York suggests that although a shellfish-dominated ecosystem appears beneficial from an economic perspective, it is highly risky. Like simplified agricultural systems, these shellfisheries are unstable in the long-term and at great risk of collapse from disease, species invasions and climate change. Warming and acidification of our oceans due to greenhouse gas emissions is expected to affect shellfish worst. Ocean acidification, in particular, will limit the ability of scallops and other shellfish to form proper shells, and lead to widespread mortality.

Lead author, Leigh Howarth, says: “Prawns are now the most valuable fishery in the UK, with catches currently worth over £110 million a year. But this fishery has come to exist only after we overexploited populations of cod, haddock and other predators. If shellfish now collapsed the social consequences for fishermen would be devastating. There are simply very few remaining species left to target.”

The study reports similar findings from all over the world. In the United States and Canada, catches of lobster, scallops and crab have also come to dominate following the collapse of cod. However, disease and climate change again put these species at great risk. While in the Black Sea, Baltic and off the west coast of Africa, overfishing of large predators have caused the ecosystems to become overrun with jellyfish, resulting in severe oxygen depletion and eruptions of hydrogen sulphide, thereby wiping out important food chains across 100,000 square kilometres of seabed.

Co-author Dr Bryce Stewart adds: “Shellfish make a valuable contribution to our fisheries. But we cannot just assume everything is rosy. There is an urgent need for continued improvements in management of finfish fisheries, and an ecosystem approach which rebuilds the diversity, resilience and productivity of our oceans into the future.”

Co-author Professor Callum Roberts concludes: “The rise of shellfish has been welcomed by many as a lifeline for the fishing industry. However, such changes are not a result of successful management, but rather a result of management failure, a failure to protect stocks and their habitats in the face of industry innovation and overfishing. This study highlights why the UK needs to urgently act to protect our seas. We need more marine protected areas to stop our seas from becoming a wasteland and to restore the diversity and productivity of fisheries well into the future.”

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