Splitfin flashlight fish uses bioluminescent light to illuminate plankton

Fish in the lab produced more light at night, in presence of planktonic prey

Date: February 8, 2017

Source: PLOS

The flashlight fish uses bioluminescent light to detect and feed on its planktonic prey, according to a study published February 8, 2017 in the open-access journal PLOS ONE by Jens Hellinger from Ruhr-University, Bochum, Germany, and colleagues.

The splitfin flashlight fish, Anomalops katoptron, is one of many ocean-dwelling animals that produces its own bioluminescent light using symbiotic bacteria. The fish has light organs located under its eyes such that the light can be turned on and off by blinking, like a flashlight. Little is known about the function and purpose of the Morse code-like blinking patterns displayed by the fish.

To investigate how the flashlight fish uses bioluminescent illumination, Hellinger and colleagues examined the blink frequency of a school of flashlight fish under different laboratory conditions. They found that during darkness at night time, the flashlight fish blink very frequently, at 90 blinks per minute, with the light being on and off for an approximately equal amount of time. However, when the flashlight fish detected living planktonic prey in the experimental tank at night, their light organs were opened for more time, keeping the light on longer, and they blinked five times less frequently than in the absence of prey.

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Scientists using new technology to track endangered basking sharks as the creatures reach UK shores

Plankton is attracting the sharks directly into the reaches of researchers

TOM BAWDEN

ENVIRONMENT EDITOR 

Friday 15 May 2015

The average basking shark may be the size and weight of a double-decker bus, but these giant fish are still notoriously hard to find.

Scientists have so far struggled to track the endangered fish, meaning that very little is known about the species. But all this is about to change – thanks to the amount of plankton found in UK waters at this time of year..

The plankton is attracting the sharks – one of just three shark species that eat plankton – directly into the reaches of researchers. As a result, scientists are now poised to start tagging the sharks for the first time, allowing them to track their movements via GPS.

The move forms part of a groundbreaking project off the Cornish coast that seeks to protect basking sharks.

Continued ...

Shift in Arabia sea plankton may threaten fisheries: Growing 'dead zone' could short-circuit food chain

A growing "dead zone" in the middle of the Arabian Sea has allowed plankton uniquely suited to low-oxygen water to take over the base of the food chain. Their rise to dominance over the last decade could be disastrous for the predator fish that sustain 120 million people living on the sea's edge.

Scientists at Columbia University's Lamont-Doherty Earth Observatory and their colleagues are the first to document the rapid rise of green Noctiluca scintillans, an unusual dinoflagellate that eats other plankton and draws energy from the sun via microscopic algae living within its cells. Noctiluca's thick blooms color the Arabian Sea an emerald green each winter, from the shores of Oman on the west, to India and Pakistan on the east.

In a study published this week in Nature Communications, the researchers show how the millions of green algae living within Noctiluca's cells allow it to exploit an oxygen-starved dead zone the size of Texas. They hypothesize that a tide of nutrient-rich sewage flowing from booming cities on the Arabian Sea is expanding the dead zone and feeding Noctiluca's growth.

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Plankton Adjusts to Changing Ocean Temperatures

Mar. 8, 2013 — Imagine trying to swim through a pool of honey. Because of their small size, this is what swimming in water is like for tiny marine plankton. So, it was often assumed they would be easy prey, especially in the dense viscosity of colder waters, but that is not necessarily so.

Texas Tech Associate Professor and Whitacre Endowed Chair in Mechanical Engineering Jian Sheng, along with biologists Brad Gemmell and Edward Buskey from the University of Texas Marine Science Institute, have discovered new information that explains how these tiny organisms overcome this disadvantage.

Their paper, titled "A compensatory escape mechanism at low Reynolds number" was published in the current issue of Proceedings of the National Academy of Sciences.

"The purpose of the study was in trying to determine the effects of climate change at the very base of the food chain," Sheng said.

As one of the most abundant animal groups on the planet, many species, including many commercially important fish species, rely on planktonic copepod nauplii at some point during their life cycle. Understanding the ability of these animals to respond to changes in the environment could have direct implications into understanding the future health of our oceans.

By independently varying temperature and viscosity, Sheng recorded their movements with 3-D high speed holographic techniques developed by the Sheng lab at Texas Tech.

"At 3,000 frames per second, it was like tracking a racecar through a microscope," Sheng said. "We were able to determine that the plankton adapted to changes in viscosity by altering the rhythm of its pulsing appendage."

The response, built-in to its natural muscle fiber, was only triggered by changes in temperature, Sheng said. It could not compensate for changes in viscosity due to environmental pollution, such as algae blooms or oil spills.

http://www.sciencedaily.com/releases/2013/03/1303081

33057.htm

The Acid Test: Armor-Covered Plankton Adapt to Warming World

Tiny armor-covered creatures that float along with the ocean's currents may adapt and survive, if badly, as their watery world warms and becomes more acidic, a new study finds.

Even so, the plankton may become flimsier and could turn into more of a "french fry" than a nutritious snack for its consumers.

As more carbon dioxide, a greenhouse gas, gets pumped into the atmosphere, and ultimately dissolves in the oceans, the seas are becoming more acidic. How this will impact life in the oceans is not known, though various studies have undertaken the challenge to find out.

In the new study, a trio of scientists at the Helmholtz Center for Oceanographic Research in Kiel, Germany, bred a variety of phytoplankton, called Emiliania huxleyi, to tolerate higher levels of carbon dioxide dissolved in the water.

Read on:  http://www.livescience.com/19557-global-warming-acidic-oceans-plankton.html

Natural phenomenon turns Maldives sea water brighter than the Milky Way Read more: http://www.metro.co.uk/weird/895162-natural-phenomenon-turns-maldives-sea-water-brighter-than-the-milky-way#ixzz1rMMGSvLd

Visitors to the Maldives expect to see spectacular scenery – but this colourful light display was something else. 

The Maldives tide turned electric blue (Picture: Doug Perrine/Barcroft Media)

The bright blue glow came from the beach on Vaadhoo Island after local plankton reacted with oxygen in the sea water to produce a light brighter than the Milky Way.

The natural phenomenon, called ‘bio-luminescence’, is hardly ever seen close to land and was captured by photographer Doug Perrine on a trip to the Indian Ocean.

He told AOL: 'This picture was taken on a starry, but moonless night.

'Each small wave lapping onto the shoreline was lit up like sheets of lightning.

'The plankton creating the light show was concentrated along the edge of the beach. The organisms creating it were large enough to be seen with the naked eye.'

Expert Peter Franks explained the phenomenon, saying: 'When jostled, each organism will give off a flash of blue light created by a chemical reaction within the cell.

'When billions and billions of cells are jostled — say, by a breaking wave — you get a seriously spectacular flash of light.'

The rare phenomenon is usually only seen further away from land when ships stir up the sea bed.

http://www.metro.co.uk/weird/895162-natural-phenomenon-turns-maldives-sea-water-brighter-than-the-milky-way

'Flying plankton' escape predatory fish

Tiny shrimp-like creatures called copepods break through the ocean's surface and leap through the air to escape predators, US scientists say.

They have been investigating how the brightly-coloured Pontellid copepods, which live close to the surface, are so abundant yet so conspicuous to fish.

Writing in Proceedings of the Royal Society B, the scientists say copepods travel further in air than in water.

Predators are also left confused about where they will land, they say.

Almost all commercially important fish, including cod, pollock and whiting, feed on copepods.

There are reports from the late-19th Century of copepods breaking through the water surface but observers at the time thought this was to allow them to moult.

A later report proposed jumping was part of an escape from predators but was not confirmed.

Read on:  http://www.bbc.co.uk/news/science-environment-17430640

See further into plankton

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http://e-edition.metro.co.uk/2010/04/19/ - p23.