Science is the poetry of Nature.







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Posts tagged "marine biology"

beautyofmicroscopy:

A micrograph of a diatom with Rheinberg illumination.

Source: Frank Fox, http://www.mikro-foto.de/diatomeen-mit-rheinberg-filter.html, via Wikimedia Commons.

(via kenobi-wan-obi)

Ocean Glow Stick: Sea Worm Emits Strange Blue Glow

One common sea worm has a rather uncommon trick: Chaeteopterus variopedatus – also known as the parchment tube worm for the paperlike tubes it builds for itself and lives within throughout its life — secretes a bioluminescent mucus that makes it glow blue.

Now, scientists are a step closer to understanding the mechanisms behind the worm’s glow.

The parchment tube worm can be found on shallow, sandy seafloors all around the world. Its glow sets it apart from other tube worms, most of whichdon’t glow, and other shallow water organisms, which typically emit green light, not blue.

Green light is more typical of shallow-water bioluminescencebecause it travels farther than any other color on the light spectrum, a useful quality in the turbid near-shore environment.

griseus:

IN SCIENCE TERMS, JAPAN HAS NO NEED AT ALL TO KILL WHALES

Final arguments from the defence and prosecution were heard in mid-July, and the world court is now considering its judgment. At issue is Japan’s right to conduct its seasonal “scientific” whaling program in Antarctic waters. But the case has involved arguments about how to define science itself.

The legal challenge to Japan has been brought to the International Court of Justice (ICJ) in the Hague by Australia, which has asked the Netherlands-based court to find that Japan’s whaling program is illegal because it is actually commercial whaling — not scientific research that is permissable under the 1982 moratorium on commercial whaling declared by the International Whaling Commission (IWC), which went into effect in the 1985/86 coastal and pelagic hunting seasons.

Allan Boyle, a professor of public international law at the University of Edinburgh, made the claim that if Japan’s current whaling program was not scientific, then neither were the research activities of numerous institutions worldwide that use fisheries data to assess sustainable catch levels.

  • More: The Japan Times 
  • Photo:  A Minke whale and her 1-year-old calf are hauled aboard the Nisshin Maru, the world’s only whale-factory ship, in the Southern Ocean in February 2008. In this case, Japan’s ‘legal research’ advertised on the ship’s stern left a large wound from an explosive harpoon in the calf’s belly. | AUSTRALIAN CUSTOMS AND BORDER PROTECTION SERVICE

(via kenobi-wan-obi)

outreachscience:

What gives the sea that smell we love?

It has been known for some time that corals serve as the main producer of dimethylsuphoniopropionate (DMSP), the chemical which acts as the seed for clouds and that gives the sea its unique sent, but until recently it was not known that it was not just the algae living with the coral that produced DMSP, but also the young coral animals, or polyps.

In a paper published in the journal Nature, a documented increase of 54% in the levels of DMSP was observed when polyps were introduced into the setting. “… In fact we could smell it [DMSP] in a single baby coral,” said co-author Cherie Motti from the Australian Institute of Marine Science. The researchers also found that when the temperature of the water was increased the polyps produced ~76% more DMSP. This could be used as an indicator for warming sea temperatures, but would also forewarn a mass die-off of the corals. This is of importance because of the role clouds place in climate regulation in the tropics; if the corals die off because of increasing temperatures less DMSP will be produced and thus less clouds will form leading to an even higher increase in sea temperatures. This is known as a negative feedback loop.

nationalaquarium:

DC UPDATE: This Giant Pacific octopus was among the first 38 animals transported to our Baltimore facility today. 

Get the full behind-the-scenes update on how we transport animals.

(via ilovecephalopods)

trynottodrown:

Ctenophores by rdbowlus

mad-as-a-marine-biologist:

An insight into the career of a marine biologist studying Manta Rays in South America.

Why Fish Don’t Need to Be ‘Schooled’ in Swimming

How do fish swim in schools, effortlessly coordinating their every move? The answer appears to be ingrained in their genes.

The genetic basis underlying the complex, social behavior of schooling is revealed in two studies published Sept. 12 in the journal Current Biology. The studies suggest that schooling is not a learned behavior, and instead show it relies on several regions of the fish genome.

The findings may point to the genetic underpinning of why humans also are social, and tend to gather in groups, some experts said, although others debated this.

abluegirl:

The Strange Beauty of Diatoms and Phytoplankton - Full Gallery

Colorful phytoplankton blooms off the coast of France.  Nasa writes:

Blooms can be a blessing to other marine species, as these tiny floating plants often feed everything from zooplankton to fish to whales. But some algae and plankton blooms can turn dangerous, either through the production of chemical toxins or by severely depleting the oxygen supply in the ocean and creating “dead zones” that suffocate marine creatures.

Pulsing corals. Scientists hypothesize that the movement of the coral keeps oxygen from building up near by, improving the availability of carbon dioxide for the photosynthetic algae that the coral rely on.  The pulsation also stirs the water to improve nutrient supplies. Only corals of the Xeniidae pulsate.

Read more about the study at Science News.

Cancer detection equipment shows us why some corals resist bleaching

Coral bleaching is a huge problem made worse by global warming. It threatens extremely productive ecosystems that are home to countless marine species. Yet some corals do better than others wen exposed to the same hostile environment. Why is that? Scientists at Northwestern University and the Field Museum of Natural History asked themselves that very question, and they think they found the answer using optical technology designed for early cancer detection.

The researchers discovered that reef-building corals scatter light in different ways to the symbiotic algae that feed the corals. Corals that are less efficient at light scattering retain algae better under stressful conditions and are more likely to survive. Corals whose skeletons scatter light most efficiently have an advantage under normal conditions, but they suffer the most damage when stressed.

The findings could help predict the response of coral reefs to the stress of increasing seawater temperatures and acidity, helping conservation scientists preserve coral reef health and high biodiversity. (source)

So the corals that were the “fittest” (in the natural selection meaning of the word) in the past are turning out to be disadvantaged compared to their less efficient cousins under today’s environment. This is the first research to show that light-scattering properties are a risk factor for corals. Hopefully this will help us devise ways to better protect coral reefs, as they are the most fertile biodiversity hotspots in our planet’s oceans.

The whole study was published under an open access license, so you can read it here.

Full Article

Squid’s Daily Rhythms Are Controlled by Glowing Symbiotic Bacteria

At nightfall, the Hawaiian bobtail squid digs itself out of the sand and rises into the ocean water like a spaceship taking off. It switches on its cloaking device: glowing bacteria inside its body light up, disguising the squid’s silhouette against the moonlight for any predators swimming below. As sleek a vehicle as it appears, though, the bobtail may not totally outrank its microscopic crewmembers. The bacteria seem to power a clock inside the squid’s body that can’t function without them.

Hiding during the day and hunting at night in shallow Pacific waters, Euprymna scolopes clearly has a working circadian clock. Researchers had noticed, though, that the squid’s light organ—the specialized pocket inside its body that houses its bacterial helpers—seemed to have a rhythm of its own. The Vibrio fischeri bacteria give off fluctuating amounts of light throughout the day, for one thing. And the bacteria have their own daily rhythm of gene expression (when various genes are turned on or off), explains Margaret McFall-Ngai, a microbiologist at the University of Wisconsin, Madison.

McFall-Ngai and her coauthors looked for genes linked to circadian rhythms within the squid. They found two types of “cry" genes, which are known to control internal clocks throughout the animal and plant kingdoms. One gene had a daily cycle of activity in the squid’s head—which is what you’d expect, since animals’ main circadian clocks are in our brains. Other clocks can be elsewhere in the body, though, and this is what researchers found with the second cry gene. It was cycling only within the light organ.

Baby squid, which hadn’t yet collected bacterial friends in their light organs, didn’t show the same cycling. So it seemed that the bacteria themselves were driving the daily rhythms in the light organ. When the researchers let squid fill their light organs with defective, non-glowing bacteria, the cry gene still didn’t cycle properly. This suggested that the glow of the bacteria was the crucial ingredient.

Full Article

Iceland volcano ash cloud triggers plankton bloom

The 2010 Icelandic volcanic eruption, which disrupted European flights, also had a “significant but short-lived” impact on ocean life, a study shows.

Ash from the Eyjafjallajokull volcano deposited dissolved iron into the North Atlantic, triggering a plankton bloom.

The authors said it was good fortune they were at sea at the time as it provided a unique opportunity to sample the ocean during a volcanic eruption.

The findings appear in the Geophysical Research Letters journal.

In April 2010, the eruption sent an ash plume several kilometres into the atmosphere, causing ash to deposited across up to 570,000 sq km of the North Atlantic Ocean.

The five-week volcanic activity was still ongoing when a team of researchers arrived in the Iceland Basin region aboard a research vessel.

"Our study was unique in the sense that we were the first to undertake sampling at sea of volcanic ash deposition and the chemical and biological effects in the surface ocean," explained lead author Eric Achterberg from the National Oceanography Centre Southampton, UK.

"In addition, we were able to sample the ocean region again a few months after the eruption and observe the changes since the eruption.

"The opportunity to sample during the eruption and also a couple of months after the event allowed us to obtain a unique insight into the effects of the ash deposition on the biology and chemistry of the Iceland Basin."

Three years earlier, the team had shown that the production of phytoplankton - microscopic plants that form a key component of marine food chains - was limited by the availability of dissolved iron, which was essential for the tiny plants’ growth.

Prof Achterberg told BBC News what the in-situ team was able to record: “Biological experiments showed that the volcanic ash released the iron that stimulated phytoplankton growth.

"The effect of the volcanic ash inputs were nevertheless short-lived as the extra iron supplied by the volcano resulted in rapid biological nitrate removal, thereby causing nitrogen limitation of the phytoplankton population."

So while the additional dissolved iron triggered an earlier-than-usual phytoplankton bloom, as the metal triggered growth in a greater number of phytoplankton cells, the bloom was only 15-20% larger than normal because the growth was limited by the amount of available nitrogen, another vital ingredient required for the organisms to develop.

As well as playing an important role in food chains, phytoplankton also absorb carbon dioxide from the atmosphere.

Oceans are considered to be one of the planet major players in the global carbon cycle, but the carbon uptake in the region where the eruption occurred has limited capacity.

"The high latitude North Atlantic Ocean is a globally important ocean region, as it is a sink for atmospheric carbon dioxide and an area where deep water formation takes place," Prof Achterberg observed.

"A limit to the availability of iron in this region means that the ocean is less efficient in its uptake of atmospheric carbon dioxide."

However during the bloom triggered by the ash deposits from the eruption, the team recorded that it was a shortage of nitrogen that limited the size of the phytoplankton bloom and - as a result - the volume of carbon dioxide uptake.

Prof Achterberg concluded: “The 2010 Eyjafjallajokull eruption therefore resulted in a significant but short lived perturbation to the biogeochemistry of the Iceland Basin.”

Full Article
Image Source

biologyoffishes:

image

(Blind Mexican cave fish Astyanax fasciatus)

The blind Mexican cave fish lacks vision and thus cannot see a wall right in front of its face. However, they rarely hit walls while swimming. So the question arises: how do they prevent themselves from hitting obstacles that they cannot see?

Scientists have determined that they use what they call hydrodynamic imaging. A. fasciatus uses hydrodynamic imaging by creating a flow field around themselves and sensing the perturbations in that field. 

image

(A. fasciatus avoiding a head-on collision with the wall)

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(A physical model created to visualize the velocity (A-E) and pressure (F-J) contours used for hydrodynamic imaging against a head-on wall by A. fasciatus)

To create the flow field, A. fasciatus swims in short controlled bursts. By doing so, they create a flow field (velocity and pressure) around them. As the fish approaches the wall, the flow field deforms, which the fish senses with its lateral line, and adjusts their swimming trajectory accordingly for.

image

(A. fasciatus avoiding contact with wall parallel to its body)

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(A physical model created to visualize the velocity (A-E) and pressure (F-J) contours used for hydrodynamic imaging against a parallel wall by A. fasciatus

And as you can imagine, the same principle applies for the fish when swimming parallel against a wall; the fish senses the deformation in the flow field with its lateral line and adjusts its swimming trajectory accordingly.

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(A. fasciatus with its lateral line function removed lacks the ability to perform hydrodynamic imaging)

The above figure shows A. fasciatus specimens whose lateral lines were made dysfunctional. As you can see, they lack the ability to perform hydrodynamic imaging and need direct contact, be it with their face, pectoral fin, or other parts of their body, in order to sense the wall. 

Sources: Windsor, Tan, and Montgomery 2008, Windsor et al 2010a, Windsor et al 2010b