Why Is the Gulf of Maine Warming Faster Than 99% of the Ocean?
"The Gulf of Maine’s location at the meeting point of two major currents, as well as its shallow depth and shape, makes it especially susceptible to warming.
Late last month, four endangered sea turtles washed ashore in northern Cape Cod, marking an early onset to what has now become a yearly event: the sea turtle stranding season. These turtles—in last month’s case, Kemp’s ridley sea turtles—venture into the Gulf of Maine during warm months, but they can become hypothermic and slow moving when colder winter waters abruptly arrive, making it hard to escape. “They are enjoying the warm water, and then all of a sudden the cold comes, and they can’t get out fast enough,” said Andrew Pershing, an oceanographer at the Gulf of Maine Research Institute in Portland, Maine. [...]"
What could cause the Mississippi Bight to become hypoxic?
"Coastal regions with low dissolved oxygen (known as hypoxia) can lead to poor water quality and harm regional fisheries. These areas of low dissolved oxygen are expanding and expected to continue growing in coming years due to human impacts on the environment.
A recent article published in Continental Shelf Research explores aspects of the environmental conditions that can potentially lead to hypoxia in the Mississippi Bight region of the northern Gulf of Mexico. This area extends from Apalachicola in Florida to the Mississippi River Delta. [...]"
[German] Dem Ozean geht die Luft aus
"In den tropischen und subtropischen Meeren existieren in mittleren Tiefen riesige sauerstoffarme Zonen. Im Zuge des Klimawandels dehnen sie sich immer stärker aus. Auch in Küstenregionen entstehen durch Stickstoffbelastung aus der Landwirtschaft lebensfeindliche Zonen ohne Sauerstoff – mit verheerenden Folgen für das marine Ökosystem [...]"
[German] TV reports about ocean deoxygenation in the german media
Oregon Now Has A Hypoxia Season, Just Like A Wildfire Season
"Scientists say warming ocean temperatures mean Oregon’s coastal waters now have a low-oxygen season, or hypoxia season, just as the state’s forests have a fire season.
Hypoxia is a condition in which the ocean water close to the sea floor has such low levels of dissolved oxygen that the organisms living down there die.
Some of the first signs came in 2002 when dead crabs were hauled up in crab pots. Since then, scientists and crabbers say things have worsened."
Author: Kristian Foden-Vencil
Shift in large-scale Atlantic circulation causes lower-oxygen water to invade Canada’s Gulf of St. Lawrence
"The Gulf of St. Lawrence has warmed and lost oxygen faster than almost anywhere else in the global oceans. The broad, biologically rich waterway in Eastern Canada drains North America’s Great Lakes and is popular with fishing boats, whales and tourists.
A new study led by the University of Washington looks at the causes of this rapid deoxygenation and links it to two of the ocean’s most powerful currents: the Gulf Stream and the Labrador Current. The study, published Sept. 17 in Nature Climate Change, explains how large-scale climate change already is causing oxygen levels to drop in the deeper parts of this waterway."
Source: University of Washington
Author: Hannah Hickey
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Earth's oxygen increased in gradual steps rather than big bursts
"A carbon cycle anomaly discovered in carbonate rocks of the Neoproterozoic Hüttenberg Formation of north-eastern Namibia follows a pattern similar to that found right after the Great Oxygenation Event, hinting at new evidence for how Earth's atmosphere became fully oxygenated.
By using the Hüttenberg Formation, which formed between a billion and half a billion years ago, to study the time between Earth's change from an anoxic environment (i.e. one lacking oxygen) to a more hospitable environment that heralded the animal kingdom, a team of researchers led by Dr. Huan Cui of the NASA Astrobiology Institute at the University of Wisconsin–Madison discovered a sustained, high level of carbon. This influx of carbon, coupled with changes in other elements, indicates how changing levels of oceanic oxygen may have lent a helping hand to early animal evolution. [...]"
Acid coastal seas off US putting common fish species at risk
Scientists have recently discovered that marine creatures can be adversely affected by hypercapnia, a condition of too much dissolved CO2 in seawater (CO2 partial pressure, or pCO2). When this level rises above 1000 micro atmospheres (1000 μatm), some fish species suffer cognitive problems and disorientation, such as losing their way or even swimming towards predators. Surface ocean CO2 partial pressures tend to be around 400 μatm, so until now scientists have thought that hypercapnia was a problem which would only become apparent over time in subsurface waters. [...]"
Back to the future of climate change
Researchers are looking to the geologic past to make future projections about climate change. Their research focuses on the ancient Tethys Ocean (site of the present-day Mediterranean Sea) and provides a benchmark for present and future climate and ocean models.
Source: Science Daily