Worse
than we thought: Oceans are now a
plastic soup
The New Scientist March 25,
2011
http://www.newscientist.com/article/dn20295-pollutiontrawling
-voyage-finds-oceans-plastic-soup.html
Pollution-trawling
voyage finds ocean's plastic
'soup'
By Ferris Jabr
If you trawl a fine mesh net
through any of the
globe's five subtropical gyres
- giant ocean
vortexes where currents
converge and swirl
unhurriedly - you will haul on
deck a muddle of
brown planktonic goop, the
occasional fish, squid
or Portuguese man-of-war -
and, almost certainly,
a generous sprinkling of
colourful plastic
particles, each no larger than
your fingernail.
Every flake of plastic cup or
shard of toothbrush
handle is a sponge for
persistent organic
pollutants (POPs) -
potentially hazardous
compounds that do not degrade
easily and cling to
any hard surface they find.
The fate of all this
plastic determines not only
the health of marine
life, but also our own; if
fish are feasting on
these toxic morsels, then we
probably are too.
Last month researchers from
the 5 Gyres Institute
in Santa Monica, California,
and the Algalita
Marine Research Foundation in
Long Beach,
California, sailed into
Piriápolis, Uruguay.
They
had just completed the third
leg of the first
expedition ever to study
plastic pollution in the
South Atlantic subtropical
gyre. In every single
trawl, the team discovered
plastic.
"This issue has only recently
come to the
public's attention," says Anna
Cummins,
co-founder of 5 Gyres. "We're
trying to document
the issue and get baseline
information because
there is such a scarcity of
data."
Plastic dust
There are still significant
gaps in the data the
crew can collect, however. The
nets that they use
cannot capture plastic
particles that are smaller
than one-third of a millimetre
across. "After a
certain size these particles
just disappear,"
says Cummins. "What is their
ultimate state? They
could very well break down to
a size where they
are ingested by fish."
Cummins also explains that
trawling gathers
plastic particles from surface
waters only.
Different kinds of plastic may
be suspended at
different depths - a dreadful
rainbow of rubbish
spanning the ocean from top to
bottom - but no
one has done the research to
find out.
What 5 Gyres researchers are
currently
investigating, however, is
whether
surface-feeding fish are
ingesting plastic - and
if so, what that does to them.
Chelsea Rochman,
who studies marine ecology and
ecotoxicology at
San Diego State University in
California, joined
the 5 Gyres team in November
for a month-long
trawl in the South Atlantic.
In addition to
sampling the water and
plastic, Rochman used a
special net to collect around
660 lanternfish - a
ubiquitous family of small
bioluminescent fish
that make up around 65 per
cent of all deep sea
fish biomass. Lanternfish
inhabit the dim depths
during the day, but swim to
the surface at night
to feed, so if any fish would
have plastic in
their guts, it would be these
guys.
Back at her lab, Rochman has
started analysing
the water and plastic samples
for the presence of
POPs. She has also started
slicing open the
lanternfish so she can
determine if they are
eating plastic and whether
POPs are accumulating
in their tissues. Rochman
wants to see whether
fish caught in highly polluted
areas of the gyres
have more plastic in their
guts and higher levels
of POPs than those taken from
less polluted
waters. Confirming that
distinction would suggest
that fish are indeed consuming
toxic morsels.
In another lab experiment,
Rochman fed one group
of fish a diet infused with
plastic, and another
group a plastic-free diet.
Preliminary results
show that the fish which ate
plastic endured
significant weight loss and
liver damage. "We are
going to look for tumours,
cell death and
congestion in the organs that
filter toxins," she
says.
Plastic, plastic,
everywhere
Plastic in the ocean would not
be so worrisome if
only certain areas were
polluted, but it appears
to travel everywhere. Worse,
it's hard to pin
down exactly where, say, the
remains of a candy
wrapper blown out to sea in
China will eventually
drift. One tool is providing
some answers,
however. For at least two
decades oceanographers
have deployed thousands of
Lagrangian drifting
buoys, which are designed to
map surface ocean
currents rather than wind
patterns or waves.
"We realised that our buoys
are in fact a kind of
marine debris," says Nikolai
Maximenko of the
University of Hawaii in
Honolulu, who
collaborated with 5 Gyres
researchers to identify
which areas of the ocean
should have especially
high levels of plastic
pollution. Wherever the
buoys gather most densely, the
reasoning goes, is
also where plastic particles
should cluster. And
that is what the researchers
have found so far:
all our plastic waste meets
and circulates in the
gyrating wastes of the
ocean.
More surprising is that
despite the lure of the
gyres, the buoys - and,
therefore, probably
plastic in general - really
get around. "It's
amazing to see the global
patterns," says
Maximenko. "I just found out
that one surface
drifter went very close to the
North Pole in
summer 2009, and another made
two loops around
Antarctica."
What researchers have
established so far is that
the plastic in the oceans is
persistent and
pervasive. Investigations into
what all this
pollution means for wildlife
and people are just
getting started, but the early
signs are not
reassuring. "The ocean is not
infinite. It
doesn't have room for our
waste," says Cummins.
