Jellyfish thrive in the man-made disruption of the oceans

SEPTEMBER 24, 2019

by Laure Fillon

Jellyfish are breeding at a much higher rate than before, thanks to changes in their enviroment wrought by human activity

Thousands of them plague our beaches to the horror of holidaymakers who dread their sting, but thanks to man's disruption of the oceans, jellyfish are thriving.

Jellyfish have been on Earth longer than we have—they are believed to have roamed the oceans for nearly 600 million years.

But human activity, from over-fishing to plastic waste and climate change, has created an environment in which they are even more at home.

The proliferation of the jellyfish could lead to what some observers are calling the "jellyfication" of the oceans, which are facing profound changes according to a draft UN report due out on Wednesday.

Fabien Lombard, a French marine biologist at the Sorbonne University specialising in the ecology of plankton and jellyfish, would not go that far.

"There are more jellyfish in certain zones in the world," he told AFP: the Black Sea, off the Namibian coast and the Sea of Japan.

It is not clear if their presence has increased in other parts of the world, because it is difficult to actually count them, although worldwide database was set up in 2014 to track them.

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Deep-Sea Explorers Find Rare Shapeshifting Jellyfish with a Prize Inside

By Brandon Specktor - Senior Writer

Part ghost, part plastic bag, all amazing.

What in the name of Neptune's beard is that thing? A ghost? An alien? The ghost of an alien?

Such were the questions that vexed a team of deep-sea scientists aboard the Nautilus research vessel earlier this month, when their underwater recon robot encountered a limp, limbless creature hovering like a ghostly lantern over the Pacific seafloor. As the team watched, the bell-shaped blob suddenly transformed, ballooning into a long, translucent windsock with a mysterious red splotch stuck to its innards.

The blob, the researchers revealed in a recent video of the encounter, was no alien (it's never aliens), but one of the rarest-seen and least-studied jellyfish in the sea. 

It's called Deepstaria (named for the research vessel that first discovered the genus in the 1960s), and has been seen only a dozen or so times in the last half-century. Researchers don't know much about the armless, shapeshifting sack, but they do know it has a habit of expanding its body to engulf any prey trusting enough to swim nearby.

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The return of JellyWatch

March 20, 2019 by Kim Fulton-Bennett, Monterey Bay Aquarium Research Institute

Are jellyfish populations increasing around the world? Like the weather, jellyfish blooms are something that many people talk about, but few people do anything about. One exception would be MBARI's Steve Haddock, a marine biologist who has been studying jellies for more than two decades. Haddock recently rolled out a new and improved web site (jellywatch.org) that allows citizen scientists around the world to report jellyfish blooms.

Haddock first set up the JellyWatch site about 10 years ago, in an attempt to use citizen science to find out about jelly blooms worldwide. Designed by Haddock and two summer interns, the original JellyWatch site was a joint effort by MBARI and the Monterey Bay Aquarium.

As Haddock explained at the time, "People have been talking about jelly blooms increasing around the world, but we don't really have a lot of data on this. So it's hard to know how localized these events are. That's why we created this website. The idea is that everyday people can get involved in a real ocean research project. Their eyes are important instruments in this study."

The jellywatch.org site was quite popular; by March 2010 it already had observations from every continent except Antarctica. For years it allowed people from all over the world to report and share jellyfish sightings, as well as photos and observations of other transient ocean events.

Unfortunately, due to difficulties with funding and website hosting, the JellyWatch site went dormant in 2018. But just this month, Haddock rolled out a new and improved JellyWatch site, funded in part through a grant from the National Science Foundation.

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First jellyfish genome reveals ancient beginnings of complex body plan

Date:  December 3, 2018

Source:  University of California - Davis

Jellyfish undergo an amazing metamorphosis, from tiny polyps growing on the seafloor to swimming medusae with stinging tentacles. This shape-shifting has served them well, shepherding jellyfish through more than 500 million years of mass extinctions on Earth.

"Whatever they're doing has really worked for them," said David Gold, an assistant professor of paleobiology in the UC Davis College of Letters and Science.

The first in-depth look at the genome of a jellyfish -- the moon jelly Aurelia aurita -- reveals the origins of this successful survival strategy. The Aurelia genome, published online Dec. 3 in the journal Nature Ecology and Evolution, indicates early jellyfish recycled existing genes to morph from polyp to medusa. The results suggest animals can radiate into new niches and forms fairly easily.

"These findings provide further evidence that evolution doesn't necessarily make the genetic code more complex," said Gold, a lead researcher on the genome study. "Jellyfish can build a big, complex life history using many of the same genes found in simpler animals."

The research team was led equally by Gold, who performed much of the work as a postdoctoral fellow at the California Institute of Technology, and by Takeo Katsuki, a project scientist at the Kavli Institute for Brain and Mind at UC San Diego.

The genome: a multi-use tool

Jellyfish come from one of the oldest branches on the animal family tree, the phylum Cnidaria, which includes corals and anemones. Jellyfish were probably the first muscle-powered swimmers in the open ocean. They appeared in the late Precambrian Era, a period of major geologic and ecological changes that preceded the Cambrian explosion of animal life.

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Common jellyfish is actually two species, scientists find

Researchers determine that US Atlantic sea nettle and the Atlantic bay nettle are individual species

Date:  November 22, 2017

Source:  University of Delaware

University of Delaware professor Patrick Gaffney and alumnus Keith Bayha, a research associate with the Smithsonian's National Museum of Natural History, have determined that a common sea nettle jellyfish is actually two distinct species.

The Atlantic sea nettle is one of the most common and well known jellyfish along the U.S. East Coast, especially in the Chesapeake Bay and Rehoboth Bay where they commonly sting swimmers in large numbers. Since it was described nearly 175 years ago, the jellyfish has been assumed to be a single species.

The discovery that is was actually two distinct species, Gaffney said, was made possible by DNA sequencing techniques

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Under the sea ice, behold the ancient Arctic jellyfish

October 24, 2017 by Kevin Krajick

The doings of creatures under the Arctic sea ice are many, but they are rarely observed by humans; it's pretty hard to get under the ice to look. In recent years, marine biologist Andy Juhl and his colleagues have gotten around this problem by driving snowmobiles several miles from Point Barrow, Alaska, out onto the adjoining frozen Chukchi Sea, drilling holes in the four-foot-plus thick ice, and poking in a video camera attached to an small underwater vehicle.

Among the things that they have observed: sizable Chrysaora melanaster jellyfish floating by, trailing their foot-long-plus tentacles along the shallow bottom. Their presence came as a surprise: adult jellyfish, or medusae, are generally thought to live only a few months. Scientists had assumed that the species survived winter only in a life stage called polyps–formless masses that cling to rocks and release little baby medusae in the spring. In a scientific paper out this week, Juhl and colleagues say the videos indicate that the creatures in fact last through winter. They could even be several years old–the Methuselahs of medusae.

"One reason we were interested was, first of all, we saw them, and it was kind of weird," said Juhl, a researcher at Columbia University's Lamont-Doherty Earth Observatory. "The whole study is based on videos we made over several years." Also, he says, the rich pollock fishery in the nearby Bering Sea is the engine for "everything fish"–fish sticks, fish paddies and other mystery-meat-type marine fast foods. But in some years, jellyfish numbers in the Bering Sea swell, and fishing nets can get seriously clogged–a problem that may crescendo over several years before dying back again. The study may reveal something about the jellyfish population dynamics that drive these cycles.

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Mysterious 'Cosmic' Jellyfish Spotted in Remote Ocean Depths

By Tia Ghose, Senior Writer | March 1, 2017 07:13am ET 

An ethereal, 'cosmic' jellyfish was spotted in some of the deepest reaches of the ocean, hovering near a previously unexplored seamount.

The luminous sea creature, which may be a completely new species, was spotted by a remotely operated underwater vehicle (ROV) roughly 9,800 feet (3,000 meters) below sea level in a remote region of the Pacific Ocean near American Samoa. The creature was discovered at the previously unexplored seamount, called Utu Seamount, by the members of the National Oceanic and Atmospheric Administration's (NOAA) 2017 American Samoa Expedition.

After the dive, Allen Collins, an invertebrate zoologist with NOAA's National Systematics Lab, initially identified the creature as Benthocodon hyalinus. Still, there's a possibility that the jellyfish could be a species previously unknown to science, Collins said. 

"It is potentially new. There really is no way to be definitive about it, though, because specimens would need to be observed under a microscope and using genetics," Collins told Live Science in an email.

The logic behind classing this creature as a separate species is that, while B. hyalinus typically has gonads — or sexual organs — distributed along all eight canals, this little creature has gonads extending along only the outer half of these canals, Collins added.

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Hundreds of jellyfish invade New Zealand coastline

Warmer sea temperatures possible reason for mass jellyfish landings on beaches from Nelson in the south island to Whangarei in the far north
 

Eleanor Ainge Roy in Dunedin

Wednesday 12 October 2016 06.25 BST Last modified on Wednesday 12 October 2016 07.08 BST

 

Thousands of kilometres of New Zealand coastline have been invaded by giant jellyfish, a phenomenon that has been linked to warmer sea temperatures.

In the last month mass jellyfish landings have been reported on beaches from Nelson in the south island to Whangarei in the top of the north island.

The Department of Conservation suspects more mass landings may have gone unreported or unsighted.

The jellyfish have been identified by marine biology expert Dr Lisa-ann Gershwin as Lion’s Mane – the world’s largest jellyfish – in Whangarei, and its close relative Desmonema in Nelson.

Gershwin, who is director of the Australian Marine Stinger Advisory Services, said the invasion suggested a significant bloom in the local jellyfish population, but the presence of them so early in the season was strange.

“I get excited any time there is jellyfish activity, and their welfare is not a concern because their population is not endangered,” said Gershwin, who has discovered 200 new species of jellyfish during the course of her career.

“New Zealand can probably expect to see more of these landings in the coming years, as jellyfish take advantage of prime breeding conditions in the oceans, which help them grow in super abundance.”

Gershwin said multiple factors could have contributed to a population explosion this season, but likely contenders included warming sea waters providing fertile breeding grounds, nutrient rich seas and a lack of natural predators for the juvenile jellyfish due to over-fishing.

Gershwin said any jellyfish landings in large numbers were always “interesting phenomena”, and gave scientists more opportunities to study the creatures up close.

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