Off California, purple sea urchins are devouring a kelp forest.

Off California, purple
sea urchins are
devouring a kelp forest.
By TONY BARBOZA
Culling a menace
ELOWthe gently rolling
waves off Palos Verdes
Peninsula, a spiny purple
menace is ravaging what should be
a thriving kelp forest.
Millions of sea urchins - scrawny,
diseased and desperate for food
- have over-run a band ofthe shallow sea floor, devouring kelp and
crowding out most all other life at a
time the giant green foliage is making a comeback elsewhere along the
California coast.
In an effort to remedy the situation, scientists and divers will spend
the next five years culling the
urchins from more than 60ha of
coastal waters degraded years ago
by pollution. Once the purple, golf
ball-size creatures are under control, young kelp should be able to
take hold on the rocky sea floor and
grow into the undulating canopies
that sustain hundreds of species of
marine life.
'Trillions of kelp spores are out
there, falling on the sea floor,"
said Tom Ford, director of marine
programmes for the Santa Monica
Bay Restoration Foundation, the
non-profit leading the project in
conjunction with environmental
groups, aquariums, fishermen
and research institutions. "They
just can't get established because
they're getting mowed down."
B
said Bob Bertelli, chairman of the
California Urchin Commission.
Regionally, kelp has been making
a slow but steady rebound as pollution controls in recent decades
have cleaned up coastal waters. A
period of cold, nutrient-rich water
has accelerated that resurgence in
the last several years, with aerial
surveys showing the kelp forest
more widespread than it's been in
decades.
Once a giant kelp anchors itself
to a reef, it can grow up to half a
metre a day. But in the barren zone
off Palos Verdes, urchins have sat
stubbornly in the way of recovery.
Smaller urchin removal efforts - off
Malibu, for example - were able
to bring the canopies back within
a year, Ford said, giving his group
confidence to move ahead with a
larger endeavour.
Other scientists, however, warn
that removing urchins does not
guarantee the return of kelp.
"You need to shift the system
back, but in the long run some
ofthese areas will just remain
urchin barrens no matter what you
do," said Ed Parnell, who studies
coastal ecosystems at the Scripps
Institution of Oceanography in La
Jolla..
Pas failures
Population control:
establi5hJ1atur~1I\l
Diversare killingpurple sea urchins(inset)to reduce their density and clear the wayfor kelpto re-
-CI
_
Other experts said the culling
project was reminiscent of past
efforts that ultimately proved ineffective, such as the 1970s' practice
of scattering quicklime, a caustic
white powder, over the water to kill
urchins and boost production for
the kelp-harvesting industry.
"In retrospect that seemed
really unnecessary," said Gordon
Hendler, who studies sea urchins
for the Natural History Museum of
LosAngeles County. "I don't know
whether cleaning urchins off specific reefs is really going to make a
difference in the big picture."
Kelp's revival will also probably
be hindered by the next EINino,
which brings ashore warm, nutri~e_nt_-JlQQI:.JI\lateL,nd churns
up
lUJlC lUC 5Jdlll
Malibu, for example - were able
to bring the canopies back within
a year, Ford said, giving his group
confidence to move ahead with a
larger endeavour.
Other scientists, however, warn
that removing urchins does not
guarantee the return of kelp.
"You need to shift the system
back, but in the long run some
of these areas will just remain
urchin barrens no matter what you
do," said Ed Parnell, who studies
coastal ecosystems at the Scripps
Institution of Oceanography in La
Jolla.
51CCH JVIJd5C J;) HJdl\.-
ing a comeback elsewhere along the
California coast.
In an effort to remedy the situation, scientists and divers will spend
the next five years culling the
urchins from more than 60ha of
coastal waters degraded years ago
by pollution. Once the purple, golf
ball-size creatures are under control, young kelp should be able to
take hold on the rocky sea floor and
grow into the undulating canopies
that sustain hundreds of species of
marine life.
"Trillions of kelp spores are out
there, falling on the sea floor,"
said Tom Ford, director of marine
programmes for the Santa Monica
Bay Restoration Foundation, the
non-profit leading the project in
conjunction with environmental
groups, aquariums, fishermen
and research institutions. "They
just can't get established because
they're getting mowed down."
Past faH;.res
r"rulation contro~
In July, divers started killing an
estimated 4.8 million purple sea
urchins - which rarely are harvested for food - striking through their
pincushion-like exoskeletons with
pointed-tip geology hammers. The
goal is to reduce their density from
as many as 70 per sqm to two. The
thinning will leave behind fewer,
healthier urchins, clearing the way
for kelp to re-establish naturally
in a place where it has declined by
more than half.
Over the years, environmental
groups have repeatedly attempted
to restore kelp forests by removing
urchins aQd transplanting healthy
seaweed. But the scale of this latest endeavour reflects the growing
belief that some ecosystems have
been so altered by humans that
they require radical intervention to
function again.
"We don't want to wait until it's
gone so we have to start planting
kelp," Ford said. "Let's go in there
now while there's still something to
build on."
A fast-growing alga, giant kelp is
the backbone of a rich coastal ecosystem. Its translucent green blades,
Population control: Diversare killingpurple sea urchins(inset)to reduce their densityand clear the wayfor kelpto reestablish naturally.- MCT
held afloat with gas-filled bladders,
tower up from the sea floor to
form canopies that provide shelter
and nutrients for a diverse marine
community. Yet over the last century, kelp declined steeply off the
California coast as storm runoff,
erosion and other shore-based pollution clouded the water and made
it harder for sunlight to penetrate.
As kelp struggled - and predators
like sheep head, lobsters and sea
otters declined - sea urchins moved
in.
"Now these (urchin populations)
are so large and so well-established
that few predators will enter,"
said Dave Witting, a fish biologist
with the National Oceanic and
Atmospheric Administration who is
working on the project.
On a recent series of dives,
half a dozen scientists aboard the
Xenarcha, a 9m research vessel,
pulled on hooded wetsuits and
descended 15m below the chilly
water's surface to the sea floor.
First they examined a healthy
kelp forest just down the coast from
the urchin zone, taking inventory
of the sea life amid the swaying
green columns: rockfish, surf perch
and kelp bass, among other species.
Then they motored over to a corner
of the desolate "urchin barren" and
got to work, following a 2m-wide
path and hammering away at the
slow-moving creatures that clung to
the rocky reef.
It's the beginning of a project that
will take years, with twice-a-week
expeditions by as many as a dqzen
dive boats working in a grid pattern
to thin the urchins and monitor
whether the kelp takes hold and
sea life returns. The project also is
drawing on the expertise of commercial divers based in San Pedro,
who have joined the urchin culling
in hopes of establishing more viable
harvesting grounds. The invading
purple urchins have gobbled up
nutrients and stunted the growth
of red urchins, whose bright orange
gonads - known as uni - are harvested to supply restaurants and
sushi bars.
'There's no nutritional value in
an empty sea urchin, and that's
what you have in an urchin barren,"
Other experts said the culling
project was reminiscent of past
efforts that ultimately proved ineffective, such as the 1970s' practice
of scattering quicklime, a caustic
white powder, over the water to kill
urchins and boost production for
the kelp-harvesting industry.
"In retrospect that seemed
really unnecessary," said Gordon
Hendler, who studies sea urchins
for the Natural History Museum of
LosAngeles County. "I don't know
whether cleaning urchins off specific reefs is really going to make a
difference in the big picture."
Kelp's revival will also probably
be hindered by the next EINino,
which brings ashore warm, nutrient-poor water and churns up
severe winter storms that can tear
the algae from the sea floor.
The US$2.5mil (RM8mil) Palos
Verdes effort is being funded by the
Montrose Settlements Restoration
Programme, a group of state and
federal trustees that have set aside
money for fish habitat restoration under a 2001 settlement with
industrial polluters who dumped
toxic DOTand PCBsinto the ocean
off the peninsula from the 1940s to
the early 1970s.
Ifthe restoration succeeds, backers have their sights set on more
isolated waters that have lost kelp
forest to urchins, such as around
Southern California's offshore
islands. - LosAngeles Times!
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