When diving in the Gulf of Maine a few years back, Jennifer
Dijkstra expected to be swimming through a flowing kelp forest that
had long served as a nursery and food for juvenile fish and
But Dijkstra, a University of New Hampshire marine biologist,
saw only a patchy seafloor before her. The sugar kelp had declined
dramatically and been replaced by invasive, shrub-like seaweed that
looked like a giant shag rug.
I remember going to some dive sites and honestly being shocked
at how few kelp blades we saw, she said.
The Gulf of Maine, stretching from Cape Cod to Nova Scotia, is
the latest in a growing list of global hotspots losing their kelp,
including hundreds of miles in the Mediterranean Sea, off southern
Japan and Australia, and parts of the California coast.
Among the worlds most diverse marine ecosystems, kelp forests
are found on all continental coastlines except for Antarctica and
provide critical food and shelter to myriad fish and other
Kelp also is critical to coastal economies, providing billions
of dollars in tourism and fishing.
The likely culprit for the loss of kelp, according to several
scientific studies, is warming oceans from climate change, coupled
with the arrival of invasive species.In Maine, the invaders are
In Australia, the Mediterranean and Japan, tropical fish are
feasting on the kelp.
Most kelp are replaced by small, tightly packed, bushy seaweeds
that collect sediment and prevent kelp from growing back, said the
University of Western Australias Thomas Wernberg.
Collectively these changes are part of a recent and increasing
global trend of flattening of the worlds kelp forests, said
Wernberg, co-author of a 2016 study which found that 38 per cent of
kelp forest declined over the past 50 years in regions that had
Kelp losses on Australias Great Southern Reef threaten tourism
and fishing industries worth $US10 billion ($A13 billion).
Die-offs contributed to a 60 per cent drop in species richness
in the Mediterranean and were blamed for the collapse of the
abalone fishery in Japan.
You are losing habitat. You are losing food. You are losing
shoreline protection, said University of Massachusetts Bostons
Jarrett Byrnes, who leads a working group on kelp and climate
Kelp is incredibly resilient and has been known to bounce back
from storms and heat waves.
But in Maine, it has struggled to recover following an explosion
of voracious sea urchins in the 1980s that wiped out many kelp
Now, it must survive in waters that are warming faster than the
vast majority of the worlds oceans most likely forcing kelp to