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Earth's sixth mass extinction event under way, scientists warn
Highly Cited The Guardian 13h ago
COMMENT FROM MY EXPERIENCE
1950 WHEN I USED TO GO TO MY BACKYARD GARDEN I USED TO SEE 4 DIFFERENT TYPES OF DRAGON FLIES
MMMMM- Scientists have said it's clear that Earth is entering its sixth mass-extinction event
- Study: A third of the 27,600 species are shrinking in terms of numbers and territorial range
- "What is at stake is really the state of humanity," study author says
John D. Sutter is a columnist for CNN who focuses on climate change and social justice. Follow him on Snapchat, Twitter and Facebook or subscribe to his email newsletter.
(CNN)Many
scientists say it's abundantly clear that Earth is entering its sixth
mass-extinction event, meaning three-quarters of all species could
disappear in the coming centuries.
That's terrifying, especially since humans are contributing to this shift.
But that's not even the full picture of the "biological annihilation" people are inflicting on the natural world, according to a study published Monday
in the Proceedings of the National Academy of Sciences. Gerardo
Ceballos, an ecology professor at the Universidad Nacional Autónoma de
México, and his co-authors, including well-known Stanford University
biologist Paul Ehrlich, cite striking new evidence that populations of
species we thought were common are suffering in unseen ways.
"What is at stake is really the state of humanity," Ceballos told CNN.
Their
key findings: Nearly one-third of the 27,600 land-based mammal, bird,
amphibian and reptile species studied are shrinking in terms of their
numbers and territorial range. The researchers called that an "extremely
high degree of population decay."
The
scientists also looked at a well-studied group of 177 mammal species
and found that all of them had lost at least 30% of their territory
between 1900 and 2015; more than 40% of those species "experienced
severe population declines," meaning they lost at least 80% of their
geographic range during that time.
Looking
at the extinction crisis not only in terms of species that are on the
brink but also those whose populations and ranges are shrinking helps
show that "Earth's sixth mass extinction is more severe" than previously
thought, the authors write. They say a major extinction event is
"ongoing."
"It's the most
comprehensive study of this sort to date that I'm aware of," said
Anthony Barnosky, executive director of the Jasper Ridge Biological
Preserve at Stanford University, who was not involved in the study. Its
value, Barnosky said, is that it makes visible a phenomenon typically
unseen by scientists and the public: that even populations of relatively
common species are crashing.
"We've
got this stuff going on that we can't really see because we're not
constantly counting numbers of individuals," he said. "But when you
realize that we've wiped out 50% of the Earth's wildlife in the last 40
years, it doesn't take complicated math to figure out that, if we keep
cutting by half every 40 years, pretty soon there's going to be nothing
left."
Stuart
Pimm, chair of conservation ecology at Duke University in North
Carolina, summed up the the concept this way: "When I look out over the
woods that constitute my view from my window here, I know we no longer
have wolves or panthers or black bears wandering around. We have
eliminated a lot of species from a lot of areas. So we no longer have a
functional set of species across large parts of the planet."
This
is an important point to emphasize, Pimm said. But the new paper's
analysis risks overstating the degree to which extinction events already
are occurring, he said, and the research methodology does not have the
level of granularity needed to be particularly useful for
conservationists.
"What good
mapping does is to tell you where you need to act," Pimm said. "The
value of the Ceballos paper is a sense of the problem. But given there's
a problem, what the bloody hell are we going to do about it?"
Often,
scientists who study crisis in the natural world focus on species that
are at high and short-term risk for extinction. These plants and animals
tend to be odd and unfamiliar, often restricted to one island or
forest. You probably didn't notice, for example, that the Catarina
pupfish, native to Mexico, went extinct in 2014, according to the paper.
Or that a bat called the Christmas Island pipistrelle is thought to
have vanished in 2009.
Meanwhile, as this research shows, entire populations of other plants and animals are crashing, even if they're not yet on the brink of extinction. Some of these are well-known.
Consider
the African elephant. "On the one hand, you can say, 'All right, we
still have around 400,000 elephants in Africa, and that seems like a
really big number,' " Barnosky said. "But then, if you step back, that's
cut by more than half of what their populations were in the early part
of last century. There were well over 1 million elephants (then).
"And
if you look at what's happened in the last decade, we have been culling
their numbers so fast that if we kept up with that pace, there would be
no more wild elephants in Africa in 20 years."
Twenty years. No more African elephants. Think about that.
Barn
swallows and jaguars are two other examples, according to Ceballos, the
lead author of the paper. Both are somewhat common in terms of their
total numbers, he said, but their decline is troubling in some places.
Such
population crashes can, of course, lead to inevitable extinctions. And
currently, scientists say that species are going extinct at roughly 100
times what would be considered normal -- perhaps considerably more.
There has been some dispute lately
about whether the Earth's sixth mass extinction event already has begun
or is simply on the horizon, but there is little disagreement among
scientists that humans are driving an unprecedented ecological crisis.
And the causes are well-known. People are burning fossil fuels, contributing to climate change. They're chopping down forests and other habitat for agriculture, to the point 37% of Earth's land surface now is farmland or pasture,
according to the World Bank. The global population of people continues
to rise, along with our thirst for land and consumption. And finally,
but not exclusively, poachers are driving numbers of elephants, pangolins, rhinos, giraffes and other creatures with body parts valuable on the black market to worryingly low levels.
All of this is contributing to a rapid decline in wild creatures, both on land and in the ocean.
Ceballos' paper highlights the urgency of this crisis -- and the need for change.
"The
good news is, we still have time," he said. "These results show it is
time to act. The window of opportunity is small, but we can still do
something to save species and populations."
Otherwise, "biological annihilation" continues
COMMENT FROM MY EXPERIENCE
1950 WHEN I USED TO GO TO MY BACKYARD GARDEN I USED TO SEE 4 DIFFERENT TYPES OF DRAGON FLIES
6 DIFFERENT TYPES OF ANTS
3 DIFFERENT TYPES OF FROGS
AND MANY TYPES OF LIZARDS
NOW NOTHING REMAINS !!!!!!!!!!!
ONLY MOSQUITOS ,COCROACHES AND HOUSE FLIES RATS SURVIVED
ALL THIS HAPPENED WHEN IN 1950 D.D.T. WHERE SPRAYED TO CONTROL MALARIA MOSQUITO
FOLLOWED BY TOXIC CHEMICALS EVERY YEAR OVER THE FOOD CROPS WE EAT
I BELIEVE WE ARE ON THE WAY TO EXTINCTION OURSELVES BECAUSE OF TOXIC SPRAYS .AND ENVIRONMENTAL DAMAGE
MOSQUITOS AND RAT FEVERS ARE KILLING MANY
1960- THERE WERE NOT MUCH MOSQUITO FEVERS-(MALARIA,DENUE ETC}
WE- NEXT ON THE EXTINCTION LIST
Natural Mosquito Killers
all these natural enemies of mosquito were killed of by humans using toxic pesticides on food crops
MOSQUITOS AND RAT FEVERS ARE KILLING MANY
1960- THERE WERE NOT MUCH MOSQUITO FEVERS-(MALARIA,DENUE ETC}
WE- NEXT ON THE EXTINCTION LIST
Natural Mosquito Killers
We
have all heard the stories, purple martins can consume their weight in
mosquitoes every day, bats eat thousands of mosquitoes, "mosquito hawks"
eat nothing but mosquitoes during their entire life cycle, is any of
this true? As you'll see below natural 
predators
all play a part in mosquito control, but not to the extent that would
be acceptable as a viable means of control. This is true especially
during times of extreme mosquito numbers (after flooding or hurricanes) ,
and when levels of mosquitoes borne disease (such as WNV) are high. The
fact is there is usually no scientific data to back up the anecdotal
claims that predators such as birds, dragonflies, bats, purple martins,
and others consume "thousands of mosquitoes". Also what scientific data
does exist is often produced from a study within a controlled
environment where these predators are only offered mosquitoes, this does
not take into account the opportunistic feeding nature of most natural
predators. There are very few instances where natural predators are
quite efficient at controlling mosquito populations, although there are
exceptions to the rule. Two prime examples would be canals and ponds.
The reason that you do not find mosquitoes breeding in these places as
often is because they are usually a permanent source of water, and as
such can support a greater and varied concentration of natural
predators. All of this being said, most of these predators are extremely
beneficial in many other ways and should be protected and allowed a
place in our urban habitat. The list below is by no means meant to say
these are the only natural predators that will eat mosquitoes. Here
we'll just concentrate on the most common natural predators we see and
the ones that are most commonly surrounded by false stories concerning
their ability to control mosquito populations.
predators
all play a part in mosquito control, but not to the extent that would
be acceptable as a viable means of control. This is true especially
during times of extreme mosquito numbers (after flooding or hurricanes) ,
and when levels of mosquitoes borne disease (such as WNV) are high. The
fact is there is usually no scientific data to back up the anecdotal
claims that predators such as birds, dragonflies, bats, purple martins,
and others consume "thousands of mosquitoes". Also what scientific data
does exist is often produced from a study within a controlled
environment where these predators are only offered mosquitoes, this does
not take into account the opportunistic feeding nature of most natural
predators. There are very few instances where natural predators are
quite efficient at controlling mosquito populations, although there are
exceptions to the rule. Two prime examples would be canals and ponds.
The reason that you do not find mosquitoes breeding in these places as
often is because they are usually a permanent source of water, and as
such can support a greater and varied concentration of natural
predators. All of this being said, most of these predators are extremely
beneficial in many other ways and should be protected and allowed a
place in our urban habitat. The list below is by no means meant to say
these are the only natural predators that will eat mosquitoes. Here
we'll just concentrate on the most common natural predators we see and
the ones that are most commonly surrounded by false stories concerning
their ability to control mosquito populations.
Gambusia
Affinis also known as the mosquitofish is a live-bearing American fish
that is utilized by some mosquito control districts across the country
as a very effective predator of mosquito larvae. As far as natural
predators go I think it can be said without hesitation that the
mosquitofish is by far the most efficient natural predator of
mosquitoes. Full grown females can reach a length of up to 2.5 inches
and males up to 1.5 inches. The female Gambusia Affinis can produce
anywhere from 10-300 live free swimming young per brood and can have
between 3 to 6 broods per 
season.
The mosquitofish is known to be an opportunistic and voracious
predator. In certain studies they have been shown to consume 42-167% of
their body weight in various invertebrate prey including mosquito larvae
per day. This species as well as some other species of small predatory
fish ( such as guppies ) can be quite useful in the reduction of
mosquito larvae given the right conditions.
season.
The mosquitofish is known to be an opportunistic and voracious
predator. In certain studies they have been shown to consume 42-167% of
their body weight in various invertebrate prey including mosquito larvae
per day. This species as well as some other species of small predatory
fish ( such as guppies ) can be quite useful in the reduction of
mosquito larvae given the right conditions.
The
purple martin is an excellent example of a natural mosquito predator
who's mosquito controlling ability has often been grossly exaggerated.
Yes, they will and do eat mosquitoes but nowhere near the amount that
would be needed to consider them effective at controlling mosquito
populations. In a quote taken from the AMCA's page titled frequently
asked questions, ornithologist James Hill founder of the Purple Martin
Conservation Association (PMCA) writes, "The number of mosquitoes that
martins eat is extremely 
insignificant,
and they certainly don't control them. In-depth studies have shown that
mosquitoes comprise no more than 0 to 3 percent of the diet of
martins". In fact during daylight hours purple martins most often will
feed on larger flying insects such as June bugs, moths, bees,
butterflies, wasps, and unfortunately dragonflies, another natural
mosquito predator. In the hours just before and after sunset is usually
when mosquitoes are most active and during this time our friends the
martins are usually feeding in the treetops, which puts them way above
most mosquito activity. The purple martin is a beautiful bird, but like
other natural predators who occasionally consume mosquitoes they
probably would rather snag a nice juicy Japanese beetle or some other
large bodied flying insect than a scrawny little mosquito.
insignificant,
and they certainly don't control them. In-depth studies have shown that
mosquitoes comprise no more than 0 to 3 percent of the diet of
martins". In fact during daylight hours purple martins most often will
feed on larger flying insects such as June bugs, moths, bees,
butterflies, wasps, and unfortunately dragonflies, another natural
mosquito predator. In the hours just before and after sunset is usually
when mosquitoes are most active and during this time our friends the
martins are usually feeding in the treetops, which puts them way above
most mosquito activity. The purple martin is a beautiful bird, but like
other natural predators who occasionally consume mosquitoes they
probably would rather snag a nice juicy Japanese beetle or some other
large bodied flying insect than a scrawny little mosquito.
The
bat is another natural predator of the mosquito that is often described
as a voracious mosquito eater. In reality bats like other natural
predators of the mosquito are opportunistic feeders. This basically
means that they will eat whatever food source is available, and while
they will eat mosquitoes they do not go out and specifically hunt just
mosquitoes. In fact studies of bats in the wild have shown that they
consume mostly 
beetles,
wasps, moths, and these same studies have shown that mosquitoes make up
less than 1 percent of their total diet. While they are not the
voracious mosquito eaters that some people claim them to be, bats are
extremely beneficial little creatures. Though they have a unearned
reputation as something to be feared bats do us a great service by
eating a huge amount of other flying insects and consequently help to
control some dangerous and harmful pest.
beetles,
wasps, moths, and these same studies have shown that mosquitoes make up
less than 1 percent of their total diet. While they are not the
voracious mosquito eaters that some people claim them to be, bats are
extremely beneficial little creatures. Though they have a unearned
reputation as something to be feared bats do us a great service by
eating a huge amount of other flying insects and consequently help to
control some dangerous and harmful pest.
Dragonflies
as well as being a natural predator of the mosquito are a fascinating
and unique group of insects. Dragonflies are often referred to as
"mosquito hawks" for their supposed ability to kill thousands of
mosquitoes. Though they do consume their fair share of mosquitoes,
dragonflies like most natural predators of mosquitoes do not consume
enough mosquitoes to cause a significant impact on mosquitoes
populations in the wild. However, one thing that 
makes
the dragonfly a better predator than most is the fact that in the
aquatic larval stage one of their food sources is mosquito larvae.
Actually it is during this stage (which can last up to six years) that
they will do their most damage to mosquito populations, the reason being
that as adults they typically like to feed during the day which is when
most mosquitoes are hiding in bushes and timberlines. These dragonfly
naiads as they are called are voracious and bold little predators and
will take on almost any aquatic animal including other naiads.
makes
the dragonfly a better predator than most is the fact that in the
aquatic larval stage one of their food sources is mosquito larvae.
Actually it is during this stage (which can last up to six years) that
they will do their most damage to mosquito populations, the reason being
that as adults they typically like to feed during the day which is when
most mosquitoes are hiding in bushes and timberlines. These dragonfly
naiads as they are called are voracious and bold little predators and
will take on almost any aquatic animal including other naiads.
Damselflies
and their naiads are another natural predator of mosquitoes but
probably not to the extent of their larger brother the 
dragonfly.
Damselfly adults are easy to tell apart from their larger cousins
because of obvious size difference, however their naiads are very
similar and have the same predatory traits as dragonflies.
dragonfly.
Damselfly adults are easy to tell apart from their larger cousins
because of obvious size difference, however their naiads are very
similar and have the same predatory traits as dragonflies.
These
beautiful insects come in a wide array of colors and their naiads are
considered fairly good predators of mosquito larvae especially in the
early instars.
Frogs,
toads and their young called tadpoles are often touted as excellent for
mosquito control. In reality, while they do consume their fare share
once again it is not enough to seriously put a dent in vast mosquito
populations. When frogs and toads do consume mosquitoes
it is usually after they have transformed from tadpole to adult.
Tadpoles are mostly herbivorous and usually feed on algae and plants,
although some larger species will occasionally prey on mosquito larvae.
Although they are not the mosquito vacuum cleaners we want them to be,
frogs are extremely beneficial little creatures and are usually a
measuring stick for a healthy environment.
it is usually after they have transformed from tadpole to adult.
Tadpoles are mostly herbivorous and usually feed on algae and plants,
although some larger species will occasionally prey on mosquito larvae.
Although they are not the mosquito vacuum cleaners we want them to be,
frogs are extremely beneficial little creatures and are usually a
measuring stick for a healthy environment.
Dragonfly nymph feeding on mosquito larvae
Here is a nymph from a dragonfly of the Aeshnidae family (i presume it is, since the particular shape and colour pattern), feeding ...
Dragonfly Nymph Feeding
Dragonfly nymphs are natural predators of mosquito larvae, other aquatic insects and worms, and even small aquatic vertebrates ...
Nymph Eats Fish
The top view of an aquarium. Here you can see a dragonfly nymph. The diet of my dragonfly nymphs consists of fish. This nymph ...
- 4K
Dragonfly eating mosquito
Dragonfly eating mosquito.
Emperor Dragonfly Nymph Hunting Prey - Creekside Education Trust
The
pond at the Creekside Discovery Centre is full of life and a great
place to observe nature. Watch this Deptford "born and bred" ...
Dragonfly nymph eating a mosquito larvae
This nymph is a left over from the tadpole rescue project that maall these natural enemies of mosquito were killed of by humans using toxic pesticides on food crops
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