Page 28 - ARUBA TODAY

A28 SCIENCE
Wednesday 23 august 2017

Vanishing kelp: Warm ocean takes toll on undersea forests

By MICHAEL CASEY,
Associated Press
APPLEDORE ISLAND, Maine
(AP) — When diving in the
Gulf of Maine a few years
back, Jennifer Dijkstra ex-
pected to be swimming
through a flowing kelp for-
est that had long served as
a nursery and food for ju-
venile fish and lobster.
But Dijkstra, a University of
New Hampshire marine bi-
ologist, saw only a patchy
seafloor before her. The
sugar kelp had declined
dramatically and been re-
placed by invasive, shrub-
like seaweed that looked
like a giant shag rug.
“I remember going to
some dive sites and hon-
estly being shocked at
how few kelp blades we
saw,” she said.
The Gulf of Maine, stretch- In this June 15, 2017 photo, a sample of a shrub-like seaweed, bagged in sea water, collected in the waters off Appledore Island,
ing from Cape Cod to Maine is displayed on a dock next to a blade of kelp.
Nova Scotia, is the latest Associated Press
in a growing list of global lect sediment and prevent working group on kelp and and heat waves. of Maine. They found intro-
hotspots losing their kelp, kelp from growing back, climate change. “They pro- But in Maine, it has strug- duced species from as far
including hundreds of miles said the University of West- vide real value to humans.” gled to recover following away as Asia, such as the
in the Mediterranean Sea, ern Australia’s Thomas Wer- The Pacific Coast from an explosion of voracious filamentous red seaweed,
off southern Japan and nberg. northern California to the sea urchins in the 1980s had increased by as much
Australia, and parts of the “Collectively these chang- Oregon border is one place that wiped out many kelp 90 percent and were cov-
California coast. es are part of a recent and that suffered dramatic kelp beds. Now, it must survive ering 50 to 90 percent of
Among the world’s most di- increasing global trend of loss, according to Cynthia in waters that are warming the gulf’s seafloor.
verse marine ecosystems, flattening of the world’s Catton, a research associ- faster than the vast major- They are seeing far fewer
kelp forests are found on kelp forests,” said Wern- ate at the Bodega Marine ity of the world’s oceans — ocean pout, wolf eel and
all continental coastlines berg, co-author of a 2016 Laboratory at the University most likely forcing kelp to pollock that once were
except for Antarctica and study in the Proceedings of California, Davis. Since migrate northward or into commonplace in these
provide critical food and of the National Academy 2014, aerial surveys have deeper waters. kelp beds. But they also
shelter to myriad fish and of Sciences, which found shown that bull kelp de- “What the future holds is are finding that the half-
other creatures. Kelp also that 38 percent of kelp for- clined by over 90 percent, more complicated,” Byrnes dozen invasive seaweeds
is critical to coastal econo- est declined over the past something Catton blamed said. “If the Gulf of Maine replacing kelp are harbor-
mies, providing billions of 50 years in regions that on a marine heat wave warms sufficiently, we know ing up to three times more
dollars in tourism and fish- had data. Kelp losses on along with a rapid increase kelp will have a hard time tiny shrimp, snails and other
ing. Australia’s Great Southern in kelp-eating sea urchins. holding on.” invertebrates.
The likely culprit, accord- Reef threaten tourism and Without the kelp to eat, On their dives around “We’re not really sure how
ing to several scientific fishing industries worth $10 Northern California’s ab- Maine’s Appledore Island, this new seascape will af-
studies, is warming oceans billion. Die-offs contributed alone fishery has been a craggy island off New fect higher species in the
from climate change, cou- to a 60 percent drop in spe- harmed. Hampshire that’s home to food web, especially com-
pled with the arrival of in- cies richness in the Mediter- “It’s pretty devastating to nesting seagulls, Dijkstra mercially important ones
vasive species. In Maine, ranean and were blamed the ecosystem as a whole,” and colleague Larry Harris like fish, crabs and lob-
the invaders are other for the collapse of the aba- Catton said. “It’s like a red- have witnessed dramatic ster,” said Dijkstra, follow-
seaweeds. In Australia, the lone fishery in Japan. wood forest that has been changes. ing a dive in which bags
Mediterranean and Ja- “You are losing habitat. completely clear-cut. If you Their study, published by of invasive seaweed were
pan, tropical fish are feast- You are losing food. You lose the trees, you don’t the Journal of Ecology collected and the inverte-
ing on the kelp. are losing shoreline pro- have a forest.” in April, examined pho- brates painstakingly count-
Most kelp are replaced tection,” said University of Kelp is incredibly resilient tos of seaweed popula- ed. “What we do think is
by small, tightly packed, Massachusetts Boston’s and has been known to tions and dive logs going that fish are using these
bushy seaweeds that col- Jarrett Byrnes, who leads a bounce back from storms back 30 years in the Gulf seascapes differently.”q