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Categories: Biology: Marine, Geoscience: Oceanography

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A new study examined nitrogen fixation among diazotrophs--microorganisms that can convert nitrogen into usable form for other plants and animals -- living among sargassum. Sargassum, a brown macroalgae in the seaweed family, floats on the surface of the open ocean and provides habitat for a colorful array of marine life such as small fish, brine shrimp and other microorganisms. Previous studies have overlooked diazotrophs associated with sargassum, which could mean a historical underestimation of nitrogen fixation in the Atlantic nitrogen budget. The study found that nitrogen fixation in sargassum communities was significant.

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A subpolar species associated with Atlantic water expanded far into the Arctic Ocean during the Last Interglacial, analysis of microfossil content of sediment cores reveals. This implies that summers in the Arctic were ice free during this period.

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The Gulf Stream system plays an important role in climate. The weakening of this system that has been observed over the last two decades is therefore a cause for concern and much debate. The question is whether the measurable changes are already due to human-induced climate change -- model simulations predict such an influence with high probability for the future. A new study concludes that the currently observed weakening can be interpreted, at least in part, as a natural fluctuation following some extremely cold winters in the Labrador Sea in the 1990s.

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An international drilling expedition off the Norwegian coast confirms the theory that methane emissions from hydrothermal vents were responsible for global warming about 55 million years ago. The study shows that the vents were active in very shallow water depth or even above sea level, which would have allowed much larger amounts of methane to enter the atmosphere.

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New research has revealed the importance of mineral forms of iron in regulating the cycling of this bio-essential nutrient in the ocean. The findings pave the way for new work on the relationship between the iron and carbon cycles and how changing ocean oxygen levels may interact.

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As global climate change causes weather extremes ranging from heat waves and droughts to heavy rains and flooding, the large amounts of freshwater pouring into nearshore ecosystems are altering habitats. A team of biologists studied the impacts of low salinity and how it alters sea urchins' ability to grip and move within their habitat.

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A chemical process used in the browning of food to give it its distinct smell and taste is probably happening deep in the oceans, where it helped create the conditions necessary for life. Known as the Maillard reaction after the French scientist who discovered it, the process converts small molecules of organic carbon into bigger molecules known as polymers. In the kitchen, it is used to create flavors and aromas out of sugars. But a research team argues that on the sea floor, the process has had a more fundamental effect, where it has helped to raise oxygen and reduce carbon dioxide levels in the atmosphere, to create the conditions for complex life forms to emerge and thrive on Earth.

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Human-caused climate change has also caused extreme ocean temperatures and conditions with detrimental impacts on marine ecosystems and ocean-related ecology.  A new study explores ocean temperature data along California's Coast, finding that certain environmental conditions and the state of the ocean led to an enhanced risk for marine heatwaves and cold spells, conditions that scientists and environmental managers will need to monitor to preserve and protect vital ecosystems critical to the California ocean economy, known as the Blue Economy.

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Royal Ontario Museum announces the oldest swimming jellyfish in the fossil record with the newly named Burgessomedusa phasmiformis. This 505-million-year-old swimming jellyfish from the Burgess Shale highlights diversity in the Cambrian ecosystem.

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A newly published study describes the response to sea level rise by the silver rice rat, an endangered species only found in the Florida Keys.

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A patch of ocean in the North Atlantic is stubbornly cooling while much of the planet warms. This anomaly -- dubbed the 'cold blob' -- has been linked to changes in ocean circulation, but a new study found changes in large-scale atmospheric patterns may play an equally important role, according to an international research team.

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A new study uses nearly a century of data to show that the average heights of winter waves along the California coast have increased as climate change has heated up the planet.

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With mighty jaws and plate-like teeth, the globally endangered whitespotted eagle ray can pretty much crunch on anything. Yet, little information is available on critical components of their life history in the U.S., such as their diet. A study is the first use DNA barcoding to uncover the finer-scale feeding patterns of this protected species in Florida. The surprising results have important implications for both shellfish enhancement activities and species management.

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Scientists found that trout from lakes stocked decades ago in the Wind River Mountains have higher numbers of gill rakers, which are bony or cartilage structures in the gullets of fish that act as sieves to retain zooplankton and nourish the trout. The difference is likely a result of the trout adapting to the food sources of the once-fishless high-mountain lakes -- a change that has taken place in a relatively short period of time and at a rate that is generally consistent with the historic timing of stocking for each of the lakes.

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The smallest member of the filter-feeding family is one of the only whale species not to embark on seasonal migrations, new research finds.

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Four decades of conservation spending totaling more than $9 billion in inflation-adjusted tax dollars has failed to improve stocks of wild salmon and steelhead in the Columbia River Basin.

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Resilient corals, often referred to as 'super corals', have recently been seen as potential saviours in the face of climate change and its detrimental effects on coral reefs. Now, a team of scientists is working to better understand these corals in order to develop strategies to protect fragile ecosystems such as the Great Barrier Reef.

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Over the last several years, the residents of Santa Monica, a coastal city on the edge of Los Angeles, saw something neither they, their parents, or perhaps even their grandparents had ever seen before: a three-foot-tall dune system rising gently from the flat, groomed expanse of one of the world's most famous urban beaches. It's a six year alliance between sand, wind and vegetation, and, according to researchers, it's one way to enlist nature to help protect the coast from the impacts of climate change.

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Arctic terns -- which fly on the longest migrations of any animal on Earth -- may be able to navigate the dangers posed by climate change, new research suggests.

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Important ocean currents that redistribute heat, cold and precipitation between the tropics and the northernmost parts of the Atlantic region will shut down around the year 2060 if current greenhouse gas emissions persist. This is the conclusion based on new calculations that contradict the latest report from the IPCC.