Archive for the ‘Oceanography’ Category
Wax inside a whale’s ear stores all sorts of useful information on the animal’s exposure to pollutants and stress levels throughout life, researchers have found.
Decimated by historic whaling practices, blue whales number just 5,000–12,000 individuals worldwide, and they are threatened by entanglement in fishing nets, environmental noise and pollution. Scientists have long used whale blubber as a record of the chemicals that these enormous creatures absorb as they traverse the ocean. But analysis of blubber does not indicate when chemical contamination occurred, or how long it lasted.
Whale earwax is a fat-rich deposit that stores the same chemical data as blubber. But it also records time — similarly to the rings of a tree, the wax is laid down in light and dark bands, with each band correlating roughly to a six-month period. In baleen, or filter-feeding, whales, earwax forms a solid plug that may be tens of centimetres long and remains intact even after its death. Learn more here or here.
While the Earth’s oceans are known as five separate entities, there is really only one ocean. So, how big is it? As of 2013, it takes up 71% of the Earth, houses 99% of the biosphere, and contains some of Earth’s grandest geological features.
The largest animals ever to have lived on Earth, blue whales are colossal in every respect — including, it must be said, their poop. When a blue whale goes, it goes big. It’s hard to judge absolute distances from the photo, but in scale the deposit is nearly as long as a full-grown blue whale.
While it looks a bit foul, whales are actually the ocean’s unappreciated gardeners, playing enormous roles in nutrient and carbon cycles. In short — or perhaps in long — their poop helps make the aquatic world go round.
Whales and marine mammals can fertilize their surface waters. This can result in more plankton, more fish, and more whales. Learn more here.
An average teaspoon of ocean water contains five million bacteria and fifty million viruses – and yet we are just starting to discover how these “invisible engineers” control our ocean’s chemistry.
Humanity’s greenhouse gas emissions may be acidifying the oceans at a faster rate than at any time in the last 300 million years. The sheer speed of change means we do not know how severe the consequences will be.
As well as warming the planet, carbon dioxide seeps into the oceans and forms carbonic acid. As a result the water becomes more acidic.
The pH is currently dropping by about 0.1 per century. This ocean acidification harms organisms such as corals that rely on dissolved carbonate to make their shells. It also disrupts behaviour in some animals.
Acidification is not the only threat to the oceans from greenhouse gases. Marine life also faces a threat from rising water temperatures and less dissolved oxygen.
A mere handful of seafloor mud may contain as many species as are found in a square meter of tropical rainforest. The fantastic assemblage seen below was gathered from a single scoop of mud, about 2 inches deep and 5 inches across.
It’s easy, when you get away from the coast, to think of the oceans as a homogeneous blue. It’s a lot more complex than that! Learn more here.
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth. See:
A brinicle is the oceanic equivalent of an atmospheric icicle. Unlike an icicle, which is formed by the accumulation of layers of ice from a slow flow of water, a brinicle is formed beneath sea ice when a flow of extremely cold, salty water is introduced to an area of ocean water. Brinicles typically form in the polar regions due to the seasonally extreme cold surface temperature and salty nature of seawater.
With timelapse cameras, specialists have recorded a brinicle forming - salt water being excluded from the sea ice and sinking.
The temperature of this sinking brine, which was well below 0°C, caused the water to freeze in an icy sheath around it.
Where the so-called “brinicle” met the sea bed, a web of ice formed that froze everything it touched, including sea urchins and starfish. Learn more here.
The age of discovery may be long past, but some areas of our planet remain largely uncharted. In one of those black spots – near the South Sandwich Islands in the Southern Ocean – the British Antarctic Survey (BAS) has discovered a previously unknown chain of volcanoes.
All told a dozen previously unknown peaks were discovered beneath the waves—some up to 3,000 meters (10,000 feet) tall.
The research team also discovered several craters, ranging up to 5 km in diameter, on the nearby ocean floor. These craters are thought to have been caused by volcanoes collapsing. Learn more here or here.