Sea Monkey Study Suggests Zooplankton Migrations May Affect Ocean Currents

October 1, 2014

April Flowers for redOrbit.com – Your Universe Online

In 1957, the world was introduced to Sea Monkeys, and people were fascinated. Sea Monkeys were advertised in nearly every popular comic book, and even made a trip to space with Astronaut John Glenn in 1998 aboard Space Shuttle Discovery. The public’s fascination with the tiny brine shrimp known as Sea Monkeys mostly stems from the fact that the dehydrated eggs hatch, develop and mate given little more than a tank of salt water.

Physicists study brine shrimp for even shorter-term patterns than the life cycle. They are interested in the vertical migration that brine shrimp, and other zooplankton, engage in. Large groups migrate from the surface at night to deeper environments during the day in response to changing light conditions.

According to a new study from the California Institute of Technology (Caltech), this pattern of migration creates water currents much larger than the sum of those created by individual organisms. The study, published in Physics of Fluid, suggests that global ocean circulation patterns can be affected by the collective movement of small marine organisms on a level comparable to the wind and tides.

Brine shrimp (Artemia salina) display a tendency to move toward a light source, a phenomenon called phototaxis. Caltech researchers Monica Wilhelmus and John Dabiri induced a vertical migration pattern in a swarm of the tiny crustaceans in a large water tank using lasers of different colors. When the researchers used a blue laser in a rising motion along the side of the tank, the brine shrimp moved upward. When a green laser was kept above the tank, the shrimp stayed centered. Microscopic silver-coated glass spheres were released into the water, allowing the team to visualize the resulting currents by capturing their changing distribution throughout the migration with a high speed camera.

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New Actors in the Arctic Ecosystem

Dec. 18, 2013 — Biologists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have for the first time shown that amphipods from the warmer Atlantic are now reproducing in Arctic waters to the west of Spitsbergen. This surprising discovery indicates a possible shift of the Arctic zooplankton community, scientists report in the journal Marine Ecology Progress Series. The primary victims of this "Atlantification" are likely to be marine birds, fish and whales. The reason is that the migrating amphipods measure around one centimetre, and so are smaller than the respective Arctic species; this makes them less nutritious prey.

Amphipods have a preference which made it easy for AWI biologists to recognise these changes. This is because the sea dwellers, which are classed as zooplankton, would appear to like hiding.

Continued

Amphibian disease research yields weapon

CORVALLIS, Ore., Aug. 26 (UPI) -- U.S. researchers say they've found a freshwater species of zooplankton that can consume a fungal pathogen devastating amphibian populations around the world.

Zoologists at Oregon State University say the tiny zooplankton, called Daphnia magna, could provide a desperately needed tool for biological control of the deadly fungus, whose impact one researcher has called "the most spectacular loss of vertebrate biodiversity due to disease in recorded history."

The fungus B. dendrobatidis, dubbed a "chytrid" fungus, can disrupt electrolyte balance and lead to death from cardiac arrest in its amphibian hosts if it reaches high levels, an OSU release said Friday.

"There was evidence that zooplankton would eat some other types of fungi, so we wanted to find out if Daphnia would consume the chytrid fungus," lead researcher Julia Buck, an OSU doctoral student in zoology, said. "Our laboratory experiments and DNA analysis confirmed that it would eat the zoospore, the free-swimming stage of the fungus.

"We feel that biological control offers the best chance to control this fungal disease, and now we have a good candidate for that," she said. "Efforts to eradicate this disease have been unsuccessful, but so far no one has attempted biocontrol of the chytrid fungus. That may be the way to go."


Read more: http://www.upi.com/Science_News/2011/08/26/Amphibian-disease-research-yields-weapon/UPI-16741314394982/#ixzz1WEcc7Pqt

Motor boat turbulence kills zooplankton in estuaries

Tuesday, 19 April 2011 09:32 UK
By Matt Walker
Editor, Earth News

Turbulence generated by speeding motor boats kills significant numbers of zooplankton, a study has revealed for the first time.

Experiments on copepods, tiny crustaceans that live and float in water, show that a third die in waters frequented by propeller-driven boats.

That is significantly more than in bodies of water not used by boats.

Zooplankton play a crucial role in water ecology and their death may have hitherto unknown impacts.

Details of the discovery are published in the Journal of Experimental Marine Biology and Ecology.

"A number of studies have been performed that looked at the impacts of much smaller scale turbulence on zooplankton," said Samantha Bickel, a PhD student at the Virginia Institute of Marine Science in Gloucester Point, US.

"But to my knowledge, no one had explored the idea that the intense turbulence generated by boats could have an adverse impact on zooplankton."

These prior studies had showed that even a small amount of turbulence can affect a copepod's ability to feed and grow.

So "it seemed intuitive that the sudden and intense turbulence created by a boat could harm or even kill copepods".

With colleagues Kam Tang, and Joseph Hammond of Hampton University, Virginia, US, Ms Bickel conducted experiments to test whether that was the case.

The researchers stained the copepods using a dye, which colours live animals red, while dead ones remain unstained.

That allowed them to quickly identify how many were alive and how many were dead in each sample.

"Regions with high boat traffic exhibited a higher occurrence of copepod carcasses," Ms Bickel told BBC News.

For example, 34% of copepods were dead in a channel while only 5-6% were dead in a marina and along a shoreline.

More copepod carcasses were found inside boat wakes (14%) than outside boat wakes (7%) and the fraction of dead copepods increased with increasing turbulence intensity.

"This suggests that turbulence generated by boats can be an important source of mortality among copepods," Ms Bickel said.

"This could have a number of important impacts within aquatic systems."

Zooplankton are a critical link between phytoplankton and fish in aquatic food webs.

High mortality in copepods could reduce the ability of a zooplankton population to graze down phytoplankton blooms and reduce the amount of food available to smaller fish that eat zooplankton, says Ms Bickel.

Also, if copepod carcasses are not consumed, they could transport high quality organic materials to the sediments or be decomposed by bacteria within the water column, she adds.

"So the zooplankton biomass that would normally go towards feeding fish would be diverted to feed bacteria instead."

The scientists have not yet been able to establish how many boats might cause a problem, and much would depend on their size and speed, which have a large effect on the turbulence they create.

"When viewed at a global scale, the portion of zooplankton killed by boat-generated turbulence is probably minimal," she says.

However, turbulence could have a significant impact on zooplankton, and therefore water ecology, at a local scale.

This may be particularly so in areas of high boat traffic and in closed freshwater systems such as lakes.

http://news.bbc.co.uk/earth/hi/earth_news/newsid_9449000/9449070.stm
(Via Dawn Holloway)