Posts
Anoxic
Oceans, Biotoxins and Harmful Algae — Missing Links in Mass Dolphin
Deaths on US East Coast?
17
October, 2013
(East
Coast Dolphin Strandings by State and Year. Image source: NOAA)
According
to reports from NOAA, as of early October more than 550 dolphins had
died and washed up along the US East Coast. The deaths, which NOAA
has causally linked to morbillivirus infection, are occurring at a
more rapid pace than the massive 1987 die-off which eventually
resulted in more than 1100 East Coast dolphin deaths over the course
of a 1 year period. By the time the first three months had passed in
the 1987 die-off about 350 dolphins had perished. If the current
event lasts as long as the 1987 die-off we could possibly see nearly
2000 deaths, setting up the current event as the worst in modern
memory.
Morbillivirus
— Cause, or Symptom of a More Ominous Problem?
In
recent calls to NOAA and the various state institutes of marine
science, I continue to receive confirmation that morbillivirus is
listed as the primary cause of dolphin deaths. Most of the stranded
dolphins have tested positive for morbillivirus and the disease has
been implicated in dolphin deaths before. (For reference,
morbillivirus is the same disease that causes measles in humans and
is similarly virulent in dolphins. )
That
said, numerous scientific sources, including
The Scientific American
and researchers
at the NRDC,
have questioned whether morbillivirus is the primary cause or just a
symptom of a larger problem with ocean health. They point to research
showing stranded dolphins with high levels of biotoxins in fatty
tissue and individuals that are generally plagued by parasites and
other infections. Many of these dolphins display compromised or
weakened immune systems as a result of elevated toxicity levels.
Meanwhile, a large enough segment of these animals are among the
adult population to rule out age as a major secondary cause of
mortality.
Algae
Blooms as Source of Biotoxins
(Satellite
Shot of Green and Brown Tinted Water Indicative of Algae Blooms off
the Virginia Coast on Oct 18. Image
Source: Lance-Modis)
Sitting
on the top of the food chain as one of the oceans’ high-order
predators, dolphins consume a large volume of fish. These fish, in
turn, are fed by lower food chain sources. As food passes up the
chain, any toxin within the food will reach higher levels of
concentration, making top order predators, like dolphins, more
vulnerable to poisoning.
The
biotoxins found in recently deceased dolphins can be linked to
harmful forms of algae that tend to develop in low oxygen ocean
environments. Some of these toxins can cause various forms of food
poisoning in mammals (including humans). Others, like hydrogen
sulfide, can build up in adipose tissue to have a number of long-term
effects resulting in stresses to major organ systems, neurological
and psychological health, and strains on a body’s immunity to
disease and infection.
Most
of the dead dolphins discovered, thus far, are either males or
nursing infants. Both are more vulnerable than females to toxicity
due to the fact that males have no means of rapidly shedding
biological toxins and infants receive higher doses of harmful
substances from toxins concentrating in mother’s milk.
Fasting
Dolphins Likely to be More Affected
As
toxins build up in the dolphins’ fatty tissues, they come under
increased risk of immuno compromise and infection during times when
they tap the energy from these stores. Elevated toxicity can happen
any time a dolphin may decide to fast rather than forage. As the fats
are tapped by the body, the toxins are re-released into the dolphin’s
blood stream where they can build up to harmful levels.
Morbillivirus
Shouldn’t be So Lethal
Supporting
the biotoxin/immuno compromise theory is the fact that morbillivirus
shouldn’t carry such a high lethality rate. The virus normally only
results in death among the most vulnerable individuals — primarily
the very young, the very old, or the already weak or sick. The fact
that morbillivirus, in this case, is carrying such a high lethality
rate is a direct sign that the virus isn’t the only cause and that
a higher portion of the dolphin population is far less healthy than
is usual. High biotoxin levels in dead dolphins also point toward a
combination of causes.
Dying
Oceans and Dying Dolphins
A
recent report on the health of the world’s oceans resulted in
ominous findings that may also provide further hints as to why so
many East Coast dolphins are dying this year. The
IPSO 2013 State of the Oceans report
found that oceans were experiencing anoxia (loss of oxygen) not just
along coastal regions where human nutrient run-off was resulting in
massive algae blooms and dead zones, but also in the deep ocean.
There, in even the far off-shore waters, ocean oxygen levels were
falling. Other high order predators, requiring high oxygen levels to
sustain their high metabolisms — like the deep sea marlin — were
found to have changed their migratory patterns to avoid deep ocean,
oxygen-poor, dead zones forming and expanding throughout the world’s
oceans.
The
expanding anoxia is both an ocean killer and a direct signal of the
changes resulting from human caused climate disruption. Warmer ocean
waters hold less oxygen in solution and so they dump more into the
atmosphere. In addition, increased fresh water run-off from melting
glaciers and more intense rainfall events (due to increases in the
world’s hydrological cycle directly caused by warming), result in
less mixing of surface waters and deeper waters. Increased run-off
also results in more algae blooms which further starve the oceans of
oxygen.
These
all contribute to increasingly anoxic waters. And once the ocean
environment flips to anoxic states, it becomes a host to numerous
toxin-producing bacteria. These toxins, in turn, end up in the food
chain and directly impact the dolphins and a whole host of other
animals.
In
other words, a more anoxic ocean is an ocean that produces more
harmful bacteria. An ocean full of harmful bacteria is one that
increases the risk of dolphin mortality. And when we see spikes in
dolphin deaths, as we have on the US east coast this year and on the
US gulf coast for every year since 2010, we had better sit up and pay
attention. As it’s a clear signal that the oceans, as a whole, are
in trouble.
Implications
for Both Ocean and Land Dwellers
Because
the ocean and the atmosphere are interconnected and because humans
greatly rely on the oceans for both foods and livelihoods, it is pure
folly to ignore the ongoing plight of the world’s oceans. Toxic
fish, mass deaths of ocean animals, and a thinning of the ocean
biosphere could result in the loss of enough food to feed upwards of
a billion people. Increasing instances of toxic algae blooms will
also likely result in higher sickness and mortality rates for those
who frequently come into contact with the seas. In the most extreme
cases, blooms of hydrogen sulfide producing bacteria could poison the
air near toxic algae blooms, resulting in severe hazards for those
who live on land.
Transitioning
to a stratified, anoxic and/or Canfield ocean state is an outcome of
climate change that is all too often ignored. A risk that should be
listed among the worst potential outcomes of human greenhouse gas
emissions. A risk that has echoes in the great Permian Extinction
event in our world’s deep past. It is a danger exists now and the
growing risk of its emergence are becoming increasingly apparent.
Signal
Received?
The
dolphins, our ‘sentinels of ocean health’ are dying. And in their
deaths are a message that we should be hearing loud and clear. Will
we listen?
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