THE AGE OF JELLYFISH
2 views
Skip to first unread message
spectre
Jul 31, 2009, 2:22:00 PM7/31/09
to spectre.event.horizon.group
http://spectregroup.wordpress.com/2009/07/31/the-age-of-jellyfish/
THE JELLYFISH EFFECT
http://dsc.discovery.com/videos/news-can-jellyfish-predict-climate-change.html
http://www.wired.com/wiredscience/2009/07/jellyfish/
Jellyfish Are the Dark Energy of the Oceans
BY Brandon Keim / July 29, 2009
The fluid dynamics of swimming jellyfish have provided a plausible
mechanism for a once-wild notion: that marine animals, hidden from
sight and ignored by geophysicists, may stir Earth’s oceans with as
much force as its wind and tides. Called induced fluid drift, it
involves the tendency of liquid to “stick” to a body as it moves
through water — and a little bit of drift could add up quickly on a
global scale. “The mere act of swimming implies that some water
travels with the swimmer,” said CalTech engineer Kakani Katija, co-
author of the study in Nature Wednesday. “Drift applies to all
animals, to anything with a body.”
That the mere motion of animals could play a profound role in water-
column commingling was once considered absurd. The sea would surely
absorb the force of a flapping fin, to say nothing of a
phytoplankton’s flagellae. It was a basic principle of friction,
applied to water. But in recent years, this consensus has sprung some
leaks. When added up, winds and tides don’t quite provide enough
energy to account for the amount of water-mixing observed in the seas.
In 2004, a study found that a school of fish could cause as much
turbulence as a storm. Other researchers soon suggested that ocean
swimmers could account for the gap. Soon after that, ocean physicists
measured enormous turbulence generated by a swarm of krill, a
crustacean considered too small to have meaningful mixing effects.
Missing from their equation, however, was a physical explanation for
how tiny forces could avoid being swallowed by the friction of the
sea. One possibility, originally proposed by Charles Darwin’s
grandson, also named Charles, was that the act of swimming created
pressure differentials that pulled water along with a body, an
invisible suitcase to be unpacked along the way by cross-currents. “As
a body moves in a fluid, a high-pressure field is created in front of
the body, and a low-pressure field behind. Because fluid moves from
high to low pressure, the fluid that’s adjacent to the rear of the
body moves along with it,” said Katija. “You get a permanent
displacement of the water.”
Katija and CalTech bioengineer John Dabiri have provided the first
direct observation of this phenomenon. Using fluorescent dyes and
underwater video cameras, they’ve made visible the invisible,
producing videos of swimming jellyfish trailed by the water they came
from. If the video seems like an infinitesimal drop in the bucket
compared to winds or tides, consider that most of the ocean —
excepting the top 300 feet or so — is so placid that a couple hand-
held kitchen mixers could stir a cubic mile of it.
According to Katija and Dabiri, induced fluid drift should be caused
by any swimming animal. Their next task is to verify that it does, and
to put numbers to how much water is moved by each animal, how it
mixes, how the figures vary by body shape and size and population
density. Future findings could have a profound influence on climate
models, which do not now account for this so-called biogenic mixing.
If swimming generates tide-scale forces, then “it has an impact on
global climate. This is a rather novel twist to the whole climate
story,” said William Dewar, a Florida State University oceanographer.
“How one would extend existing models to include a biosphere mixing
input is not clear, largely because no-one has spent much time
thinking about it.”
EARTH'S IMMUNE SYSTEM?
http://www.npr.org/templates/story/story.php?storyId=111346982
Jellyfish May Help Keep Planet Cool
BY Geoff Brumfiel / July 30, 2009
Jellyfish and other related creatures may be helping to reduce the
effects of climate change by stirring up the oceans, according to a
new study in this week's issue of the journal Nature. The finding is
the latest in a decades-old debate over whether swimming animals can
contribute significantly to ocean mixing, the process by which warm
water on the surface combines with the cold water far below. Mixing
plays a role in global climate change because carbon dioxide in the
air above oceans dissolves in the surface water. Through mixing, it
can get pulled into the depths and stored there for long periods. The
process is also a key regulator of the Earth's temperature and the
ocean's nutrients. "It's important for us to understand the dynamics
of the ocean in order to really understand what's going to happen to
climate over land," says John Dabiri, a bioengineer at California
Institute of Technology in Pasadena and co-author of the paper.
Ocean Mixers
Tides and winds are known to be major players in ocean mixing, but
some researchers believe that animals might also contribute. Dabiri
and his graduate student Kakani Katija decided to find out by filming
dozens of jellyfish as they swam in the wild. Studying the movies
shows that the simple animals drag water behind them as they swim.
It's a little bit like a bicyclist in the Tour de France, says Dabiri:
"When Lance Armstrong is riding down the road, he's actually taking
quite a bit of the surrounding air along with him, and the animals are
doing something similar in the water." To avoid predators, jellyfish
and related animals often hide far below the ocean's surface during
the day and swim to the surface at night to feed, according to William
Dewar, an oceanographer at Florida State University in Tallahassee who
was not involved with the study.
Changing The Carbon Balance
If the work is correct, then it could mean that they're ferrying cold
water to the surface and warm water into the depths of the sea with
each feeding cycle. In the process, they may be taking dissolved
carbon dioxide with them far beneath the sea, changing the overall
carbon balance in the atmosphere. But, Dewar adds, there's a still a
long way to go before scientists can say for sure that animals like
jellyfish are helping to regulate the climate. Larger-scale studies
need to be carried out to understand where marine animals are living
and how they move. "What I think we can say at the moment is that it's
a plausible idea," he says.
CONTACT
John Dabiri
http://dabiri.caltech.edu/
http://dabiri.caltech.edu/people/dabiri.html
email : jodabiri [at] caltech [dot] edu
Kakani Katija Young
http://www.its.caltech.edu/~kakani/
http://www.its.caltech.edu/~kakani/research.html
email : kakani [at] caltech [dot] edu
JELLYFISH LAKE
http://www.youtube.com/watch?v=UXV1D13f0Ko
ANIMAL-INDUCED TURBULENCE
http://cat.inist.fr/?aModele=afficheN&cpsidt=15924852
Influence of animals on turbulence in the sea / by Mark Huntley, Meng
Zhou
Abstract : "Analysis of data on the hydrodynamics of swimming by 100
species, ranging in body mass (M) from bacteria to blue whales, leads
to a model of animal-induced turbulence in the ocean. Swimming speeds
and Reynolds number (Re) are strongly correlated with body mass, both
at typical cruising speeds and at escape speeds associated with
predator-prey interactions. We find that animals operating at Re >
1000 typically form schools that are concentrated by many orders of
magnitude above their average abundance. We calculate the rate of
kinetic energy production by 11 representative species of schooling
animals ranging in size from euphausiids to whales, and find it to be
of the order of 10-5 W kg-1, regardless of animal size. Animal-induced
turbulence is comparable in magnitude to rates of turbulent energy
dissipation (E) that result from major storms. The horizontal length
scale (10 to 1000 m) of energy production rate by animal schools is
comparable to the observed fine-scale variability in ε. We present
detailed case studies of 4 species-Atlantic bluefin tuna, Norwegian
herring, northern anchovy and Antarctic krill-all of which have
schooling behavior that places them within the zone of maximum
seasonal stratification where their energy production rate would be 3
to 4 orders of magnitude greater than the background average rate of
turbulent energy dissipation. We conclude that schooling animals are
an important source of fine-scale turbulent mixing in the ocean,
especially in coastal regions during summer."
OCEAN MIXING
http://ocean.fsu.edu/~lous/download/papers/dewaretal.2006.pdf
Does the marine biosphere mix the ocean?
by W.Dewar, R.Bingham, R.Iverson, D.Nowacek, L.St.Laurent, P.Wiebe
Abstract : "Ocean mixing is thought to control the climatically
important oceanic overturning circulation. Here we argue the marine
biosphere, by a mechanism like the bioturbation occurring in marine
sediments, mixes the oceans as effectively as the winds and tides.
This statement is derived ultimately from an estimated 62.7 TeraWatts
of chemical power provided to the marine environment in net primary
production. Various approaches argue something like 1% (.63 TeraWatts)
of this power is invested in aphotic ocean mechanical energy, a rate
comparable to wind and tidal inputs."
KRILL MIGRATION
http://www.livescience.com/animals/060921_critter_mix.html
Swarms of Small Creatures Stir the Sea
BY Charles Q. Choi / 21 September 2006
Swarms of tiny shrimp-like crustaceans known as krill could have a big
impact on ocean life, by churning the waters and bringing nutrients
from the depths up to the surface. The discovery also suggest that sea
life could contribute to mixing gases in the ocean. This might
influence how gases such as carbon dioxide, linked to global warming,
get trapped underwater. The windswept surface layers of the open seas
can teem with life, but scientists could not completely explain why,
since predictions suggested not enough nutrients rise up from the
abyss below to account for such abundance.
The researchers, from the University of Victoria in Canada,
investigated swarms of krill in Saanich Inlet, a fjord on Vancouver
Island. The crustaceans migrate to the surface daily as night
approaches and retreat downward as day breaks. Over the course of
three dusks and two dawns, using data gathered in boat expeditions,
the researchers discovered that in the roughly 10-minute bursts in
which the krill migrated, they increased turbulence by up to thousands
of times. "I was initially skeptical that biologically linked
turbulence could be significant. I was surprised at just how large it
could be," researcher Eric Kunze, an ocean physicist, told
LiveScience.
These findings suggest krill and other sea life could prove critical
in bringing nourishment up from the ocean depths, which are loaded
with nutrients released by surface organisms that died and sank. "The
question now is how frequently and how significant any biologically
linked turbulence really is," Kunze said. The most likely animals to
generate large amounts of ocean turbulence are roughly inch-sized
creatures that travel together in large schools or swarms, he
speculated, such as anchovies, sardines, herring or squid.
EARTH'S IMMORTALS
http://www.dailygalaxy.com/my_weblog/2009/07/the-earths-immortal-species-thriving-in-oceans.html
Genetic Rock Star: Earth's Immortal Species Thriving in Oceans
BY Luke McKinney / 7.23.09
The rock star mantra of "live fast, die young" works in reverse too -
you can trade off enjoyment for endurance. Don't smoke, drink or eat
meat and you can extend your life by decades, though what you're going
to do with all that time is another question. Now it seems that an
animal has taken this to the logical extreme, and can live forever -
the only drawback being it lives forever as a small clump of jelly.
The Hydrozoan, a small predatory sea creature like a jellyfish but
without all their well known exciting higher functions, can achieve
the dream of millions and become a child again. When adverse
environmental conditions threaten death it can collapse into a rugged
blob of cells to survive. When it re-emerges, it does so as a child -
literally building itself up all over again. Since this isn't just a
shell to hide in, but a complete structural restart, it seems possible
that it could keep this up forever.
Since one of these adverse environmental conditions is "getting sucked
into the ballast tanks of a freighter", the hardy hitchhiker has
spread all over the globe. It possesses stingers and eats things,
which are definitely qualities you don't want in something that's
unkillable and spreading worldwide, but if you're larger than a shrimp
you're still safe. If you are currently smaller than a shrimp, get
Rick Moranis to block the laser and try to be in a better comedy next
time.
We aren't in any immediate danger of knock-on effects either, as the
jetsetting jellyfish-ettes seem to be integrating quite harmlessly
into their new homes (though some shrimp might disagree). The rather
damp phoenix-stylings of the hydrozoan have obviously made them a hot
topic in genetics, but don't expect to buy your immortality pills just
yet - this is one life extension option that isn't even remotely
applicable to humans.
SIX FEET ACROSS
http://www.youtube.com/watch?v=HqfCm58SB6Y
http://news.nationalgeographic.com/news/2009/07/photogalleries/giant-jellyfish-invasion-japan-pictures/index.html
http://www.treehugger.com/files/2009/07/giant-jellyfish.php
The world--and especially the world's oceans--are full of strange
animals, but the weirdest may be the Nomura jellyfish. It can measure
up to 6 feet in diameter and weigh more than 450 pounds. Half a dozen
can break fishing lines and give a Japanese fisherman a fit. About
four years ago, the giant jellyfish started to gain notice when
fishermen, fishing the Sea of Japan for anchovies, salmon and
yellowtail, were instead catching these sea monsters in their massive
fishing nets. Now the jellyfish are again gathering in the Yellow Sea
off China and the Korean peninsula. It is expected to drift into the
Sea of Japan in the next few months. Last time the situation got so
bad, the salmon boats in northern Japan stopped going out, and it's
reported that in some places fishermen lost 80 percent of their
income. The nuclear power plants along the Japan Sea coast even sucked
the jellyfish into their water pumps used to cool the reactors.
PREVIOUSLY ON SPECTRE
[ from the archive, originally posted on spectre 4/24/07 ]
http://securityandclimate.cna.org/report/National%20Security%20and%20the%20Threat%20of%20Climate%20Change.pdf
http://www.popsci.com/popsci/science/19b1a5353f2a1110vgnvcm1000004eecbccdrcrd.html
Global warming is helping jellyfish rule the sea
BY Bjorn Carey / March 2007
"Jellyfish will actually thrive in warmer oceans- bad news for dozens
of fish species, says biologist Martin Attrill of the University of
Plymouth in England. Attrill has analyzed 50 years' worth of data from
the North Sea and found that jellyfish are more prevalent in warm-
water years. As seas continue to heat up, this could pose trouble for
cod, salmon and other commercial fish: Jellyfish not only outcompete
fish larvae for food but eat them too."
THE AGE OF JELLYFISH
http://animals.howstuffworks.com/marine-life/jellyfish.htm
http://dsc.discovery.com/news/slideshows/monster-jellyfish.html
'Jellyfish Stable State' / June 8, 2009
Giant jellyfish like this one are taking over parts of the world's
oceans as overfishing and other human activities open windows of
opportunity for them to prosper, say researchers. Jellyfish are
normally kept in check by fish, which eat small jellyfish and compete
for jellyfish food such as zooplankton, researchers said. But, with
overfishing, jellyfish numbers are increasing. These huge creatures
can burst through fishing nets, as well as destroy local fisheries
with their taste for fish eggs and larvae. Anthony Richardson of CSIRO
Marine & Atmospheric Research and colleagues reported their findings
in the journal Trends in Ecology and Evolution to coincide with World
Oceans Day. They say climate change could also cause jellyfish
populations to grow. The team believes that for the first time, water
conditions could lead to what they call a "jellyfish stable state," in
which jellyfish rule the oceans. The combination of overfishing and
high levels of nutrients in the water has been linked to jellyfish
blooms. Nitrogen and phosphorous in run-off cause red phytoplankton
blooms, which create low-oxygen dead zones where jellyfish survive,
but fish can't, researchers said. "(There is) a jellyfish called
Nomura, which is the biggest jellyfish in the world. It can weigh 200
kilograms (440 pounds), as big as a sumo wrestler and is 2 meters (6.5
feet) in diameter," Richardson said. Richardson said jellyfish numbers
are increasing in Southeast Asia, the Black Sea, the Gulf of Mexico
and the North Sea.
JELLY SWARMS
http://www.livescience.com/animals/081219-bts-jellyfish.html
The Truth Behind Global Jellyfish Swarms
BY Lily Whiteman, National Science Foundation / 19 December 2008
Large swarms of jellyfish and other gelatinous animals — sometimes
covering hundreds of square miles of ocean — have recently been
reported in many of the world's prime vacation and fishing
destinations. In this interview with Lily Whiteman of the National
Science Foundation, renowned "jellyologist" Monty Graham of the
Dauphin Island Sea Lab in Alabama discusses the origins and impacts of
such swarms. (Note: Jellyfish and other gelatinous animals are called
"jellies" here.)
Q. What types of damage have jelly swarms caused?
A. "Damage" can be seen as either economic or environmental. Recent
examples of jelly swarms that have created such problems include:
* Tourism in Australia where deadly box jellies live and in the
Mediterranean where stinging jellyfish closed down many beaches during
the summer of 2008.
* Many important fisheries, including the Gulf of Mexico, where
jellies regularly clog nets, fowl fishing gear or prey on eggs and
larvae of fish.
* Aquaculture operations are often affected. One particular example
was in 2007 when an extraordinarily large swarm of jellyfish virtually
wiped out a salmon farm off northern Ireland.
* Seafloor diamond operations off the coast of Namibia, where jellies
have clogged vacuum pipes.
* Nuclear power plants in many locations. Recently, in November 2008,
a jelly swarm clogged intake pipes at the Diablo Canyon power plant in
California, and thereby caused a temporary plant shut-down.
Q. How densely are jellies packed together in swarms?
A. In most cases, a dense swarm would be a few animals in one cubic
meter of water. However, in extreme cases, there can be more jellies
than water. Such swarms may cover a hundred miles of more of coastline
at a time.
Q. Are jelly swarms natural phenomena?
A. Yes. Jellies have likely swum and swarmed in our seas for over 600
million years. When conditions are right, jelly swarms can form
quickly. They appear to do this for sexual reproduction. Since males
need to release gametes (sperm) into the water, they need to be very
close to females. Therefore swarming behavior is just a way for them
to be close to each other.
Q. Are jelly populations increasing?
A. In some locations, jelly populations are increasing. But such
increases are regional in nature; we do not have evidence that there
are "global" increases due to global influences, but evidence is
mounting that climate change may have an effect.
Q. Are human-caused environmental problems promoting population
explosions of jellies?
A. Various types of environmental problems may promote the formation
of jelly swarms. These problems include pollution, the overharvesting
of fish, the introduction of non-native jelly species into new
habitats, the addition of artificial substrate (like fishing reefs,
and various offshore platforms) in the ocean and climate change.
Q. How may climate change promote population explosions of jellies?
A. Higher water temperatures may speed jelly reproduction as well as
extend the growing season for jellies; a longer reproduction season
could result in more jellies. Climate change may also increase the
amount of food available for jellies. Also, climate change may change
ocean currents. Changed currents may transport jellies — which drift
with currents — into new habitats. Because climate change appears to
be a world-wide phenomenon, climate change may have worldwide impacts
on jellies. But we really don’t know yet what the details regarding
interactions between climate change and jelly populations.
Q. In light of the abundance of jellies, why don’t we know more about
them?
A. Marine ecologists have traditionally regarded jellies as mere
nuisances that interfered with studies of truly important creatures.
Because of such attitudes, ecologists have traditionally gone to great
lengths to avoid jellies, rather than to study them. In fact, in the
past, when scientists accidentally caught jellies in their research
nets, they often did horrific things to jellies — like pouring bleach
over them in order to dissolve them away without destroying the hard
critters that they really wanted to study. Because jellies have
traditionally been understudied, we don’t have many accurate long-term
records of their population sizes. Therefore, in many places, we can’t
yet say for sure whether or how much jelly population sizes may be
changing.
Q. Are jellies finally getting the respect they deserve?
A. Appreciation of the ecological importance of jellies has steadily
grown since the 1980s, when jelly populations exploded in several
ecosystems, including the Black Sea. More scientists are now studying
jellies in more locations than ever before.
Q. Why are jellies particularly difficult to study?
A. Jellies are fragile and so they are often destroyed when we try to
collect them in nets. Also, jellies are difficult to preserve because
their bodies are destroyed by many types of preservatives. Plus, many
types of jellies are too big or too small to be raised and studied in
captivity.
Q. Have you ever been badly stung by jellies while researching them?
A. Yes, but not more than an uncomfortable sting. I do have colleagues
that have been hospitalized while studying jellies, though.
Q. In light of the fact that jellies are difficult to study and the
ocean is so complex, how can scientists identify the individual
impacts of each type of environmental disturbance on jelly
populations?
A. By developing computer models of marine ecosystems. One of my main
activities now is to help build such models, and then manipulate
various factors in these models — such as water temperature or
salinity and the size of fish harvests — in order to identify their
relative influences on jelly populations.
Q. If some places have too many jellies, why don’t people just eat
them?
A. Some jellies are eaten by humans and have long been considered a
delicacy in some Asian countries. In addition, processed jellies are
sold in some Asian food stores in the U.S.
Q. As long-lived, hardy and often abundant creatures, are jellies "the
cockroaches of the sea?"
A. Absolutely not! Jellies are much better than cockroaches! Jellies
represent among the oldest living animals on Earth and if the past is
prologue, these highly successful creatures will continue to thrive
even under the changing conditions of today's oceans. I have said
before that most likely cockroaches will be long gone when the last
jelly swims in a lonely sea.
BAD INDICATOR
http://dsc.discovery.com/news/2008/06/18/jellyfish-ecosystems.html
Jellyfish Booms Signal Ecosystems Out of Whack
BY Jerome Cartillier / June 18, 2008
The dramatic proliferation of jellyfish in oceans around the world,
driven by overfishing and climate change, is a sure sign of ecosystems
out of kilter, warn experts. "Jellyfish are an excellent bellwether
for the environment," explains Jacqueline Goy, of the Oceanographic
Institute of Paris. "The more jellyfish, the stronger the signal that
something has changed." Brainless creatures composed almost entirely
of water, the primitive animals have quietly filled a vacuum created
by the voracious human appetite for fish. Dislodging them will be
difficult, marine biologists say. "Jellyfish have come to occupy the
place of many other species," notes Ricardo Aguilar, research director
for Oceana, a international conservation organization.
Nowhere is the sting of these poorly understood invertebrates felt
more sharply than the Mediterranean basin, where their exploding
numbers have devastated native marine species and threaten seaside
tourism. And while much about the lampshade-like creatures remains
unknown, scientists are in agreement: Pelagia noctiluca -- whose
tentacles can paralyze prey and cause burning rashes in humans -- will
once again besiege Mediterranean coastal waters this summer. That, in
itself, is not unusual. It is the frequency and persistence of these
appearances that worry scientists.
Two centuries worth of data shows that jellyfish populations naturally
swell every 12 years, remain stable four or six years, and then
subside. 2008, however, will be the eighth consecutive year that
medusae, as they are also known, will be present in massive numbers.
The over-exploitation of ocean resources by man has helped create a
near-perfect environment in which these most primitive of ocean
creatures can multiply unchecked, scientists say. "When vertebrates,
such as fish, disappear, then invertebrates -- especially jellyfish --
appear," says Aguilar.
The collapse of fish populations boost this process in two important
ways, he added. When predators such as tuna, sharks, and turtles
vanish, not only do fewer jellyfish get eaten, they have less
competition for food. Jellyfish feed on small fish and zooplankton
that get caught up in their dangling tentacles. "Jellyfish both
compete with fish for plankton food, and predate directly on fish,"
explains Andrew Brierley from the University of St Andrews in
Scotland. "It is hard, therefore, to see a way back for fish once
jellyfish have become established, even if commercial fishing is
reduced."
Which is why Brierley and other experts were not surprised to find a
huge surge in the number of jellyfish off the coast of Namibia in the
Atlantic, one of the most intensely fished oceans in the world.
Climate change has also been a boon to these domed gelatinous
creatures in so far as warmer waters prolong their reproductive
cycles. But just how many millions, or billions, of jellyfish roam the
seas is nearly impossible to know, said scientists. For one things,
the boneless, translucent animals -- even big ones grouped in large
swarms -- are hard to spot in satellite images or sonar soundings,
unlike schools of fish. They are also resist study in captivity, which
means a relative paucity of academic studies. "There are only 20
percent of species of jellyfish for which we know the life cycle,"
said Goy.
And the fact that jellyfish are not commercially exploited, with the
exception of a few species eaten by gastronomes in East Asia, has also
added to this benign neglect. But the measurable impact of these
stinging beasts on beach-based tourism along the Mediterranean has
begun to spur greater interest in these peculiar creatures whose
growing presence points to dangerous changes not just in the world's
oceans, but on the ground and in the air as well.
THE JELLYFISH EFFECT
http://dsc.discovery.com/videos/news-can-jellyfish-predict-climate-change.html
http://www.wired.com/wiredscience/2009/07/jellyfish/
Jellyfish Are the Dark Energy of the Oceans
BY Brandon Keim / July 29, 2009
The fluid dynamics of swimming jellyfish have provided a plausible
mechanism for a once-wild notion: that marine animals, hidden from
sight and ignored by geophysicists, may stir Earth’s oceans with as
much force as its wind and tides. Called induced fluid drift, it
involves the tendency of liquid to “stick” to a body as it moves
through water — and a little bit of drift could add up quickly on a
global scale. “The mere act of swimming implies that some water
travels with the swimmer,” said CalTech engineer Kakani Katija, co-
author of the study in Nature Wednesday. “Drift applies to all
animals, to anything with a body.”
That the mere motion of animals could play a profound role in water-
column commingling was once considered absurd. The sea would surely
absorb the force of a flapping fin, to say nothing of a
phytoplankton’s flagellae. It was a basic principle of friction,
applied to water. But in recent years, this consensus has sprung some
leaks. When added up, winds and tides don’t quite provide enough
energy to account for the amount of water-mixing observed in the seas.
In 2004, a study found that a school of fish could cause as much
turbulence as a storm. Other researchers soon suggested that ocean
swimmers could account for the gap. Soon after that, ocean physicists
measured enormous turbulence generated by a swarm of krill, a
crustacean considered too small to have meaningful mixing effects.
Missing from their equation, however, was a physical explanation for
how tiny forces could avoid being swallowed by the friction of the
sea. One possibility, originally proposed by Charles Darwin’s
grandson, also named Charles, was that the act of swimming created
pressure differentials that pulled water along with a body, an
invisible suitcase to be unpacked along the way by cross-currents. “As
a body moves in a fluid, a high-pressure field is created in front of
the body, and a low-pressure field behind. Because fluid moves from
high to low pressure, the fluid that’s adjacent to the rear of the
body moves along with it,” said Katija. “You get a permanent
displacement of the water.”
Katija and CalTech bioengineer John Dabiri have provided the first
direct observation of this phenomenon. Using fluorescent dyes and
underwater video cameras, they’ve made visible the invisible,
producing videos of swimming jellyfish trailed by the water they came
from. If the video seems like an infinitesimal drop in the bucket
compared to winds or tides, consider that most of the ocean —
excepting the top 300 feet or so — is so placid that a couple hand-
held kitchen mixers could stir a cubic mile of it.
According to Katija and Dabiri, induced fluid drift should be caused
by any swimming animal. Their next task is to verify that it does, and
to put numbers to how much water is moved by each animal, how it
mixes, how the figures vary by body shape and size and population
density. Future findings could have a profound influence on climate
models, which do not now account for this so-called biogenic mixing.
If swimming generates tide-scale forces, then “it has an impact on
global climate. This is a rather novel twist to the whole climate
story,” said William Dewar, a Florida State University oceanographer.
“How one would extend existing models to include a biosphere mixing
input is not clear, largely because no-one has spent much time
thinking about it.”
EARTH'S IMMUNE SYSTEM?
http://www.npr.org/templates/story/story.php?storyId=111346982
Jellyfish May Help Keep Planet Cool
BY Geoff Brumfiel / July 30, 2009
Jellyfish and other related creatures may be helping to reduce the
effects of climate change by stirring up the oceans, according to a
new study in this week's issue of the journal Nature. The finding is
the latest in a decades-old debate over whether swimming animals can
contribute significantly to ocean mixing, the process by which warm
water on the surface combines with the cold water far below. Mixing
plays a role in global climate change because carbon dioxide in the
air above oceans dissolves in the surface water. Through mixing, it
can get pulled into the depths and stored there for long periods. The
process is also a key regulator of the Earth's temperature and the
ocean's nutrients. "It's important for us to understand the dynamics
of the ocean in order to really understand what's going to happen to
climate over land," says John Dabiri, a bioengineer at California
Institute of Technology in Pasadena and co-author of the paper.
Ocean Mixers
Tides and winds are known to be major players in ocean mixing, but
some researchers believe that animals might also contribute. Dabiri
and his graduate student Kakani Katija decided to find out by filming
dozens of jellyfish as they swam in the wild. Studying the movies
shows that the simple animals drag water behind them as they swim.
It's a little bit like a bicyclist in the Tour de France, says Dabiri:
"When Lance Armstrong is riding down the road, he's actually taking
quite a bit of the surrounding air along with him, and the animals are
doing something similar in the water." To avoid predators, jellyfish
and related animals often hide far below the ocean's surface during
the day and swim to the surface at night to feed, according to William
Dewar, an oceanographer at Florida State University in Tallahassee who
was not involved with the study.
Changing The Carbon Balance
If the work is correct, then it could mean that they're ferrying cold
water to the surface and warm water into the depths of the sea with
each feeding cycle. In the process, they may be taking dissolved
carbon dioxide with them far beneath the sea, changing the overall
carbon balance in the atmosphere. But, Dewar adds, there's a still a
long way to go before scientists can say for sure that animals like
jellyfish are helping to regulate the climate. Larger-scale studies
need to be carried out to understand where marine animals are living
and how they move. "What I think we can say at the moment is that it's
a plausible idea," he says.
CONTACT
John Dabiri
http://dabiri.caltech.edu/
http://dabiri.caltech.edu/people/dabiri.html
email : jodabiri [at] caltech [dot] edu
Kakani Katija Young
http://www.its.caltech.edu/~kakani/
http://www.its.caltech.edu/~kakani/research.html
email : kakani [at] caltech [dot] edu
JELLYFISH LAKE
http://www.youtube.com/watch?v=UXV1D13f0Ko
ANIMAL-INDUCED TURBULENCE
http://cat.inist.fr/?aModele=afficheN&cpsidt=15924852
Influence of animals on turbulence in the sea / by Mark Huntley, Meng
Zhou
Abstract : "Analysis of data on the hydrodynamics of swimming by 100
species, ranging in body mass (M) from bacteria to blue whales, leads
to a model of animal-induced turbulence in the ocean. Swimming speeds
and Reynolds number (Re) are strongly correlated with body mass, both
at typical cruising speeds and at escape speeds associated with
predator-prey interactions. We find that animals operating at Re >
1000 typically form schools that are concentrated by many orders of
magnitude above their average abundance. We calculate the rate of
kinetic energy production by 11 representative species of schooling
animals ranging in size from euphausiids to whales, and find it to be
of the order of 10-5 W kg-1, regardless of animal size. Animal-induced
turbulence is comparable in magnitude to rates of turbulent energy
dissipation (E) that result from major storms. The horizontal length
scale (10 to 1000 m) of energy production rate by animal schools is
comparable to the observed fine-scale variability in ε. We present
detailed case studies of 4 species-Atlantic bluefin tuna, Norwegian
herring, northern anchovy and Antarctic krill-all of which have
schooling behavior that places them within the zone of maximum
seasonal stratification where their energy production rate would be 3
to 4 orders of magnitude greater than the background average rate of
turbulent energy dissipation. We conclude that schooling animals are
an important source of fine-scale turbulent mixing in the ocean,
especially in coastal regions during summer."
OCEAN MIXING
http://ocean.fsu.edu/~lous/download/papers/dewaretal.2006.pdf
Does the marine biosphere mix the ocean?
by W.Dewar, R.Bingham, R.Iverson, D.Nowacek, L.St.Laurent, P.Wiebe
Abstract : "Ocean mixing is thought to control the climatically
important oceanic overturning circulation. Here we argue the marine
biosphere, by a mechanism like the bioturbation occurring in marine
sediments, mixes the oceans as effectively as the winds and tides.
This statement is derived ultimately from an estimated 62.7 TeraWatts
of chemical power provided to the marine environment in net primary
production. Various approaches argue something like 1% (.63 TeraWatts)
of this power is invested in aphotic ocean mechanical energy, a rate
comparable to wind and tidal inputs."
KRILL MIGRATION
http://www.livescience.com/animals/060921_critter_mix.html
Swarms of Small Creatures Stir the Sea
BY Charles Q. Choi / 21 September 2006
Swarms of tiny shrimp-like crustaceans known as krill could have a big
impact on ocean life, by churning the waters and bringing nutrients
from the depths up to the surface. The discovery also suggest that sea
life could contribute to mixing gases in the ocean. This might
influence how gases such as carbon dioxide, linked to global warming,
get trapped underwater. The windswept surface layers of the open seas
can teem with life, but scientists could not completely explain why,
since predictions suggested not enough nutrients rise up from the
abyss below to account for such abundance.
The researchers, from the University of Victoria in Canada,
investigated swarms of krill in Saanich Inlet, a fjord on Vancouver
Island. The crustaceans migrate to the surface daily as night
approaches and retreat downward as day breaks. Over the course of
three dusks and two dawns, using data gathered in boat expeditions,
the researchers discovered that in the roughly 10-minute bursts in
which the krill migrated, they increased turbulence by up to thousands
of times. "I was initially skeptical that biologically linked
turbulence could be significant. I was surprised at just how large it
could be," researcher Eric Kunze, an ocean physicist, told
LiveScience.
These findings suggest krill and other sea life could prove critical
in bringing nourishment up from the ocean depths, which are loaded
with nutrients released by surface organisms that died and sank. "The
question now is how frequently and how significant any biologically
linked turbulence really is," Kunze said. The most likely animals to
generate large amounts of ocean turbulence are roughly inch-sized
creatures that travel together in large schools or swarms, he
speculated, such as anchovies, sardines, herring or squid.
EARTH'S IMMORTALS
http://www.dailygalaxy.com/my_weblog/2009/07/the-earths-immortal-species-thriving-in-oceans.html
Genetic Rock Star: Earth's Immortal Species Thriving in Oceans
BY Luke McKinney / 7.23.09
The rock star mantra of "live fast, die young" works in reverse too -
you can trade off enjoyment for endurance. Don't smoke, drink or eat
meat and you can extend your life by decades, though what you're going
to do with all that time is another question. Now it seems that an
animal has taken this to the logical extreme, and can live forever -
the only drawback being it lives forever as a small clump of jelly.
The Hydrozoan, a small predatory sea creature like a jellyfish but
without all their well known exciting higher functions, can achieve
the dream of millions and become a child again. When adverse
environmental conditions threaten death it can collapse into a rugged
blob of cells to survive. When it re-emerges, it does so as a child -
literally building itself up all over again. Since this isn't just a
shell to hide in, but a complete structural restart, it seems possible
that it could keep this up forever.
Since one of these adverse environmental conditions is "getting sucked
into the ballast tanks of a freighter", the hardy hitchhiker has
spread all over the globe. It possesses stingers and eats things,
which are definitely qualities you don't want in something that's
unkillable and spreading worldwide, but if you're larger than a shrimp
you're still safe. If you are currently smaller than a shrimp, get
Rick Moranis to block the laser and try to be in a better comedy next
time.
We aren't in any immediate danger of knock-on effects either, as the
jetsetting jellyfish-ettes seem to be integrating quite harmlessly
into their new homes (though some shrimp might disagree). The rather
damp phoenix-stylings of the hydrozoan have obviously made them a hot
topic in genetics, but don't expect to buy your immortality pills just
yet - this is one life extension option that isn't even remotely
applicable to humans.
SIX FEET ACROSS
http://www.youtube.com/watch?v=HqfCm58SB6Y
http://news.nationalgeographic.com/news/2009/07/photogalleries/giant-jellyfish-invasion-japan-pictures/index.html
http://www.treehugger.com/files/2009/07/giant-jellyfish.php
The world--and especially the world's oceans--are full of strange
animals, but the weirdest may be the Nomura jellyfish. It can measure
up to 6 feet in diameter and weigh more than 450 pounds. Half a dozen
can break fishing lines and give a Japanese fisherman a fit. About
four years ago, the giant jellyfish started to gain notice when
fishermen, fishing the Sea of Japan for anchovies, salmon and
yellowtail, were instead catching these sea monsters in their massive
fishing nets. Now the jellyfish are again gathering in the Yellow Sea
off China and the Korean peninsula. It is expected to drift into the
Sea of Japan in the next few months. Last time the situation got so
bad, the salmon boats in northern Japan stopped going out, and it's
reported that in some places fishermen lost 80 percent of their
income. The nuclear power plants along the Japan Sea coast even sucked
the jellyfish into their water pumps used to cool the reactors.
PREVIOUSLY ON SPECTRE
[ from the archive, originally posted on spectre 4/24/07 ]
http://securityandclimate.cna.org/report/National%20Security%20and%20the%20Threat%20of%20Climate%20Change.pdf
http://www.popsci.com/popsci/science/19b1a5353f2a1110vgnvcm1000004eecbccdrcrd.html
Global warming is helping jellyfish rule the sea
BY Bjorn Carey / March 2007
"Jellyfish will actually thrive in warmer oceans- bad news for dozens
of fish species, says biologist Martin Attrill of the University of
Plymouth in England. Attrill has analyzed 50 years' worth of data from
the North Sea and found that jellyfish are more prevalent in warm-
water years. As seas continue to heat up, this could pose trouble for
cod, salmon and other commercial fish: Jellyfish not only outcompete
fish larvae for food but eat them too."
THE AGE OF JELLYFISH
http://animals.howstuffworks.com/marine-life/jellyfish.htm
http://dsc.discovery.com/news/slideshows/monster-jellyfish.html
'Jellyfish Stable State' / June 8, 2009
Giant jellyfish like this one are taking over parts of the world's
oceans as overfishing and other human activities open windows of
opportunity for them to prosper, say researchers. Jellyfish are
normally kept in check by fish, which eat small jellyfish and compete
for jellyfish food such as zooplankton, researchers said. But, with
overfishing, jellyfish numbers are increasing. These huge creatures
can burst through fishing nets, as well as destroy local fisheries
with their taste for fish eggs and larvae. Anthony Richardson of CSIRO
Marine & Atmospheric Research and colleagues reported their findings
in the journal Trends in Ecology and Evolution to coincide with World
Oceans Day. They say climate change could also cause jellyfish
populations to grow. The team believes that for the first time, water
conditions could lead to what they call a "jellyfish stable state," in
which jellyfish rule the oceans. The combination of overfishing and
high levels of nutrients in the water has been linked to jellyfish
blooms. Nitrogen and phosphorous in run-off cause red phytoplankton
blooms, which create low-oxygen dead zones where jellyfish survive,
but fish can't, researchers said. "(There is) a jellyfish called
Nomura, which is the biggest jellyfish in the world. It can weigh 200
kilograms (440 pounds), as big as a sumo wrestler and is 2 meters (6.5
feet) in diameter," Richardson said. Richardson said jellyfish numbers
are increasing in Southeast Asia, the Black Sea, the Gulf of Mexico
and the North Sea.
JELLY SWARMS
http://www.livescience.com/animals/081219-bts-jellyfish.html
The Truth Behind Global Jellyfish Swarms
BY Lily Whiteman, National Science Foundation / 19 December 2008
Large swarms of jellyfish and other gelatinous animals — sometimes
covering hundreds of square miles of ocean — have recently been
reported in many of the world's prime vacation and fishing
destinations. In this interview with Lily Whiteman of the National
Science Foundation, renowned "jellyologist" Monty Graham of the
Dauphin Island Sea Lab in Alabama discusses the origins and impacts of
such swarms. (Note: Jellyfish and other gelatinous animals are called
"jellies" here.)
Q. What types of damage have jelly swarms caused?
A. "Damage" can be seen as either economic or environmental. Recent
examples of jelly swarms that have created such problems include:
* Tourism in Australia where deadly box jellies live and in the
Mediterranean where stinging jellyfish closed down many beaches during
the summer of 2008.
* Many important fisheries, including the Gulf of Mexico, where
jellies regularly clog nets, fowl fishing gear or prey on eggs and
larvae of fish.
* Aquaculture operations are often affected. One particular example
was in 2007 when an extraordinarily large swarm of jellyfish virtually
wiped out a salmon farm off northern Ireland.
* Seafloor diamond operations off the coast of Namibia, where jellies
have clogged vacuum pipes.
* Nuclear power plants in many locations. Recently, in November 2008,
a jelly swarm clogged intake pipes at the Diablo Canyon power plant in
California, and thereby caused a temporary plant shut-down.
Q. How densely are jellies packed together in swarms?
A. In most cases, a dense swarm would be a few animals in one cubic
meter of water. However, in extreme cases, there can be more jellies
than water. Such swarms may cover a hundred miles of more of coastline
at a time.
Q. Are jelly swarms natural phenomena?
A. Yes. Jellies have likely swum and swarmed in our seas for over 600
million years. When conditions are right, jelly swarms can form
quickly. They appear to do this for sexual reproduction. Since males
need to release gametes (sperm) into the water, they need to be very
close to females. Therefore swarming behavior is just a way for them
to be close to each other.
Q. Are jelly populations increasing?
A. In some locations, jelly populations are increasing. But such
increases are regional in nature; we do not have evidence that there
are "global" increases due to global influences, but evidence is
mounting that climate change may have an effect.
Q. Are human-caused environmental problems promoting population
explosions of jellies?
A. Various types of environmental problems may promote the formation
of jelly swarms. These problems include pollution, the overharvesting
of fish, the introduction of non-native jelly species into new
habitats, the addition of artificial substrate (like fishing reefs,
and various offshore platforms) in the ocean and climate change.
Q. How may climate change promote population explosions of jellies?
A. Higher water temperatures may speed jelly reproduction as well as
extend the growing season for jellies; a longer reproduction season
could result in more jellies. Climate change may also increase the
amount of food available for jellies. Also, climate change may change
ocean currents. Changed currents may transport jellies — which drift
with currents — into new habitats. Because climate change appears to
be a world-wide phenomenon, climate change may have worldwide impacts
on jellies. But we really don’t know yet what the details regarding
interactions between climate change and jelly populations.
Q. In light of the abundance of jellies, why don’t we know more about
them?
A. Marine ecologists have traditionally regarded jellies as mere
nuisances that interfered with studies of truly important creatures.
Because of such attitudes, ecologists have traditionally gone to great
lengths to avoid jellies, rather than to study them. In fact, in the
past, when scientists accidentally caught jellies in their research
nets, they often did horrific things to jellies — like pouring bleach
over them in order to dissolve them away without destroying the hard
critters that they really wanted to study. Because jellies have
traditionally been understudied, we don’t have many accurate long-term
records of their population sizes. Therefore, in many places, we can’t
yet say for sure whether or how much jelly population sizes may be
changing.
Q. Are jellies finally getting the respect they deserve?
A. Appreciation of the ecological importance of jellies has steadily
grown since the 1980s, when jelly populations exploded in several
ecosystems, including the Black Sea. More scientists are now studying
jellies in more locations than ever before.
Q. Why are jellies particularly difficult to study?
A. Jellies are fragile and so they are often destroyed when we try to
collect them in nets. Also, jellies are difficult to preserve because
their bodies are destroyed by many types of preservatives. Plus, many
types of jellies are too big or too small to be raised and studied in
captivity.
Q. Have you ever been badly stung by jellies while researching them?
A. Yes, but not more than an uncomfortable sting. I do have colleagues
that have been hospitalized while studying jellies, though.
Q. In light of the fact that jellies are difficult to study and the
ocean is so complex, how can scientists identify the individual
impacts of each type of environmental disturbance on jelly
populations?
A. By developing computer models of marine ecosystems. One of my main
activities now is to help build such models, and then manipulate
various factors in these models — such as water temperature or
salinity and the size of fish harvests — in order to identify their
relative influences on jelly populations.
Q. If some places have too many jellies, why don’t people just eat
them?
A. Some jellies are eaten by humans and have long been considered a
delicacy in some Asian countries. In addition, processed jellies are
sold in some Asian food stores in the U.S.
Q. As long-lived, hardy and often abundant creatures, are jellies "the
cockroaches of the sea?"
A. Absolutely not! Jellies are much better than cockroaches! Jellies
represent among the oldest living animals on Earth and if the past is
prologue, these highly successful creatures will continue to thrive
even under the changing conditions of today's oceans. I have said
before that most likely cockroaches will be long gone when the last
jelly swims in a lonely sea.
BAD INDICATOR
http://dsc.discovery.com/news/2008/06/18/jellyfish-ecosystems.html
Jellyfish Booms Signal Ecosystems Out of Whack
BY Jerome Cartillier / June 18, 2008
The dramatic proliferation of jellyfish in oceans around the world,
driven by overfishing and climate change, is a sure sign of ecosystems
out of kilter, warn experts. "Jellyfish are an excellent bellwether
for the environment," explains Jacqueline Goy, of the Oceanographic
Institute of Paris. "The more jellyfish, the stronger the signal that
something has changed." Brainless creatures composed almost entirely
of water, the primitive animals have quietly filled a vacuum created
by the voracious human appetite for fish. Dislodging them will be
difficult, marine biologists say. "Jellyfish have come to occupy the
place of many other species," notes Ricardo Aguilar, research director
for Oceana, a international conservation organization.
Nowhere is the sting of these poorly understood invertebrates felt
more sharply than the Mediterranean basin, where their exploding
numbers have devastated native marine species and threaten seaside
tourism. And while much about the lampshade-like creatures remains
unknown, scientists are in agreement: Pelagia noctiluca -- whose
tentacles can paralyze prey and cause burning rashes in humans -- will
once again besiege Mediterranean coastal waters this summer. That, in
itself, is not unusual. It is the frequency and persistence of these
appearances that worry scientists.
Two centuries worth of data shows that jellyfish populations naturally
swell every 12 years, remain stable four or six years, and then
subside. 2008, however, will be the eighth consecutive year that
medusae, as they are also known, will be present in massive numbers.
The over-exploitation of ocean resources by man has helped create a
near-perfect environment in which these most primitive of ocean
creatures can multiply unchecked, scientists say. "When vertebrates,
such as fish, disappear, then invertebrates -- especially jellyfish --
appear," says Aguilar.
The collapse of fish populations boost this process in two important
ways, he added. When predators such as tuna, sharks, and turtles
vanish, not only do fewer jellyfish get eaten, they have less
competition for food. Jellyfish feed on small fish and zooplankton
that get caught up in their dangling tentacles. "Jellyfish both
compete with fish for plankton food, and predate directly on fish,"
explains Andrew Brierley from the University of St Andrews in
Scotland. "It is hard, therefore, to see a way back for fish once
jellyfish have become established, even if commercial fishing is
reduced."
Which is why Brierley and other experts were not surprised to find a
huge surge in the number of jellyfish off the coast of Namibia in the
Atlantic, one of the most intensely fished oceans in the world.
Climate change has also been a boon to these domed gelatinous
creatures in so far as warmer waters prolong their reproductive
cycles. But just how many millions, or billions, of jellyfish roam the
seas is nearly impossible to know, said scientists. For one things,
the boneless, translucent animals -- even big ones grouped in large
swarms -- are hard to spot in satellite images or sonar soundings,
unlike schools of fish. They are also resist study in captivity, which
means a relative paucity of academic studies. "There are only 20
percent of species of jellyfish for which we know the life cycle,"
said Goy.
And the fact that jellyfish are not commercially exploited, with the
exception of a few species eaten by gastronomes in East Asia, has also
added to this benign neglect. But the measurable impact of these
stinging beasts on beach-based tourism along the Mediterranean has
begun to spur greater interest in these peculiar creatures whose
growing presence points to dangerous changes not just in the world's
oceans, but on the ground and in the air as well.
Reply all
Reply to author
Forward
0 new messages