Tag Archives: jellyfish

jellyfish

Killer Robots Slash Jellyfish

Jellyfish blooms are increasingly causing problems. In Korea, the number of accidents and financial losses caused by jellyfish is estimated at 300 billion won (£1.8 m) per year. To combat the jellyfish, Korean researchers led by Professor Hyeon Myeong are using a team of robots, called JEROS (Jellyfish Elimination Robotic Swarm). These slash and grind the jellyfish, killing 900 kg an hour.

Jellyfish cause the fishing industry to lose money by breaking fishing nets. They sting swimmers. They block the seawater cooling systems of power plants. In 2009, a ten-ton Japanese trawler capsized after the three man crew tried to haul up a net loaded with jellyfish.

Scientists have proposed several reasons why jellyfish blooms are apparently becoming more common around the world’s coasts. One recent suggestion is that “ocean sprawl” may be an important driver of the global increase in jellyfish blooms. Ocean sprawl is the proliferation of artificial structures associated with shipping, aquaculture, other coastal industries and coastal protection. The theory is that the structures provide habitat for jellyfish polyps thus causing the increase in jellies.1 Another theory is over-fishing of predators like turtles. Polluted waters – where fertiliser run-off etc causes plankton blooms – increase the food for jellyfish.

Will robots exterminating jellyfish solve any jellyfish problems? What happens to the jellyfish parts that have been cut up?

Reducing the underlying cause of the jellyfish blooms is surely more of a solution than producing billions of jellyfish bits.

The aquatic robot designed by the Korean Higher Institute of Science and Technology (KAIST) has a mountable grinding part buoyed by two cylinders that use motors to move forward and reverse, as well as rotate 360 degrees. Data from a GIS (geographic information system) map is used to specify the region for jellyfish extermination. JEROS then navigates autonomously using a GPS (Global Positioning System) receiver and an INS (inertial navigation system).

The assembly robots maintain a set formation pattern, while calculating its course to perform jellyfish extermination. The advantage of this method is that there is no need for individual control of the robots. Only the leader robot requires the calculated path, and the other robots can simply follow in a formation by exchanging their location information via wireless communication (ZigBee).

JEROS uses its propulsion speed to capture jellyfish into the grinding part on the bottom, which sucks the jellyfish toward the propeller to be exterminated.

Further Reading
Kaist: Korean Higher Institute of Science and Technology

Jellyfish Blooms and Their Effects in the Sea of Japan

1Is global ocean sprawl a cause of jellyfish blooms?
Carlos M Duartee et al Frontiers in Ecology and the Environment 2013 11:2, 91-97


Lions Mane Jellyfish

Have you seen Basking Sharks, Jellyfish or Turtles in UK Waters?

The Marine Conservation Society wants to know if you’ve seen any basking sharks, turtles or jellyfish – in UK and Irish waters.

Jellyfish? Yes, because jellyfish are the favourite food of Leatherback Turtles. And they don’t just want to know about live jellyfish but about strandings on beaches as well. Identification of live jellyfish is usually easy but once they’ve washed up on the beach it can become more difficult. They want you to therefore send photos if possible, and offer a jellyfish identification guide.

Leatherback turtles (Dermochelys coriacea) are the largest species of turtle, and occasional visitors to the North and Irish seas. By comparing the distribution of jellyfish with environmental factors such as sea temperature, plankton production and current flow, the Marine Conservation Society (MCS) hope to understand what influences the seasonal distribution of jellyfish and leatherbacks in UK waters.

The basking shark (Cetorhinus maximus) is Britain’s largest fish. They can grow up to 11 metres long and weigh up to 7 tonnes – about the size and weight of a double-decker bus. Once numerous in the UK basking sharks were hunted for their liver oil and their populations declined to such an extent that now they are considered to be endangered in UK waters. The MCS Basking Shark Watch programme has generated the largest basking shark sightings database in the world and is instrumental in identifying surface feeding hotspots.

So if you dive around UK or Ireland, get over to the MCS site and report your sitings at http://www.mcsuk.org/what_we_do/Wildlife protection/Report wildlife sightings/Report wildlife sightings

Mauve Stinger Jellyfish

Mauve Stinger is Creature of the Month

The Mauve Stinger, or Luminescent Jellyfish, is a beautiful jellyfish. Often coloured purple, you can find it around the world in warm and temperate waters from around 12 to 30 m.

This jellyfish is the most venomous in the Mediterranean. However, its sting is usually limited to the skin surface with local pain which lasts for one to two weeks. In some cases the sting can leave scars, or pigmentation of the skin lasting for several years. Should you be stung by a jellyfish, rinse the area with vinegar for 30 minutes. If vinegar is not available use sea water: don’t use fresh water. Remove any tentacles left on the skin.

As the name suggests, the luminescent jellyfish gives off light. When water is disturbed by waves, or a ship, the jellyfish flashes attractively for a short while.

The jellyfish can move vertically, but are unable to propel themselves horizontally and so are carried by currents. They move up and down in response to migrations of their prey, zooplankton.

Intestingly, a group of jellyfish have their own collective noun, in fact they have two: a “smack” or a “fluther” of jellyfish.

Further Reading:

Mariottini, G.L.; Giacco, E.; Pane, L. The Mauve Stinger Pelagia noctiluca (Forsskål, 1775). Distribution, Ecology, Toxicity and Epidemiology of Stings.. Mar. Drugs 2008, 6, 496-513.

Jellyfish blooms move food energy from fish to bacteria

jellyfish

Jellyfish blooms move food energy from fish to bacteria

Over the last few years reports of jellyfish blooms around the world have been increasing. This is bad news for the marine food web, as the jellyfish are voracious predators of plankton, but are not readily consumed by other predators.

A new study by researchers at the Virginia Institute of Marine Science shows that jellyfish have a significant impact, drastically altering marine food webs by shunting food energy from fish toward bacteria.

The results of the study – led by Rob Condond – appear in this week’s Early Edition of the Proceedings of the National Academy of Sciences.

The researchers tracked the flow of food energy in the lab by measuring the amount of carbon taken up and released by jellyfish and bacteria within closed containers during “incubation” experiments of varying length. Carbon is the “currency” of energy exchange in living systems.

“Jellyfish are voracious predators,” says Condon. “They impact food webs by capturing plankton that would otherwise be eaten by fish and converting that food energy into gelatinous biomass. This restricts the transfer of energy up the food chain, because jellyfish are not readily consumed by other predators.”

Jellyfish also shunt food energy away from fish and shellfish that humans like to eat through their affects on the bacterial community. “Marine bacteria typically play a key role in recycling carbon, nitrogen, phosphorus, and other byproducts of organic decay back into the food web,” says Condon. “But in our study, we found that when bacteria consumed dissolved organic matter from jellyfish they shunted it toward respiration rather than growth.”

The upshot of this “jelly carbon shunt” is that bacteria in jelly-laden waters end up converting carbon back to carbon dioxide, rather than using it to grow larger or reproduce. This means the carbon is lost as a direct source of organic energy for transfer up the food web.

He adds that a host of factors, including climate change, over-harvesting of fish, fertilizer runoff and habitat modifications could help to fuel jellyfish blooms into the future. “Indeed,” he says, “we’ve seen this already in Chesapeake Bay. If these swarms continue to emerge, we could see a substantial biogeochemical impact on our ecosystems.”

Further Reading:
Robert H. Condon, Deborah K. Steinberg, Paul A. del Giorgio, Thierry C. Bouvier, Deborah A. Bronk, William M. Graham, and Hugh W. Ducklow
Jellyfish blooms result in a major microbial respiratory sink of carbon in marine systems. PNAS 2011 : 1015782108v1-201015782.
Virginia Institute of Marine Science