1. Kelp forests provide habitat for over 1800 species by providing shelter, food and protection from predators and waves. They absorb carbon dioxide and release oxygen, helping to buffer ocean acidification. 2. However, kelp forests are at risk from climate change effects like rising ocean temperatures, acidification, and stronger storms. Increased carbon dioxide is raising ocean temperatures and acidity. This stresses kelp and dissolves shells of calcifying species. 3. If emissions are not reduced, experts predict kelp forests will continue shrinking and may disappear from some areas. This would degrade coastal ecosystems and reduce their ability to absorb carbon dioxide and protect coastlines. Urgent action is needed to transition away from fossil fuels

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Help our Kelp!!!
Image by Kyle McBurnie
Kelp Forests Provide a refuge from Ocean Acidification:-
But Could They Be at Risk from Climate Change?
Within a hidden underwater forest of
dense kelp that extends to 30m deep, the
limit of most scuba divers, there is an
abundance of activity. Juvenile fish and
marine mammals, swim amongst kelp
fronds, underwater forms of exaggerated
leaves, sheltered from predators. The
vigorous frond blades are adorned with
epiphytes of flat and feather-like
calcareous algae of pink and red hues to
Image by Ian Skipworth

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green and brown turfing, bushy and foliose algae, providing a gastronomic delight for hundreds of
grazing gastropod snails, limpets and sea-urchins. These become a menu of prey for predatory whelks,
crustaceans, sea otters and fish. At the seabed holdfasts of kelp, mistakenly confused as roots, attach
to the bedrock, creating a cavern of niches. Within these niches a myriad of animals hide from
predators, whilst mobile animals crawl around the bedrock scavenging for detritus.
What are Kelp Forests?
These magnificent kelps are key habitat forming species, dominating temperate rocky reefs says
Professor Robert Steneck. They provide energy and food by photosynthesising. Supplying a safe haven
for over 1800 species, from predators and
wave exposure, they are a vital coastal and
marine landscape. Astonishingly, a single kelp
frond alone supplies a home for over 8000
individual organisms, from not only 40 species
of macroinvertebrates, such as crabs,
molluscs, sea urchins, as well as sponges and
hilarious sea-squirts, which, as their name
suggests, squirt seawater. As well as micro-
invertebrates, so small they can only be identified by high-powered microscopes, such as amphipods
and isopods that hop, skip and jump between the fronds. In addition, epiphytes, organisms that attach
themselves to kelp, such as membrane-like bryozoans and, turfing, feathery and encrusting algae that
offer a secondary home to those that choose. Kelp with coarse stipes supply additional homes for
animals and epiphytes to attach to, whilst holdfasts of various shapes, ranging from root-like to ruffled
fans, can support between 30-70 different types of species.
Just How Important Are They?
Dr. Juliet Brodie believes they are amongst the most productive ecosystems in the world, providing
over a kg of carbon per meter square per year by way of primary production. To put this into context,
this is between 3 to 10 times more than coastal phytoplankton adds Dr. Dan Smale. Although some
20% of kelp is consumed directly by grazing invertebrates, such as Sea Urchins and snails (that leave
tell-tale signs of holes where they’ve fed), 80% of its carbon is consumed as dissolved organic matter
or detritus, where older fragments of fronds have withered away with age.
Image by Brian Skerry

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Newly hatched fish make the most
of the tangled kelp, sneakily hiding
away from predatory terminators.
Whilst on the surface sea-otters
make use of the dense canopy as a
make-shift raft as they lie back,
enjoy the sunshine and break sea-
urchins with rocks for their supper,
safe from killer whale predation.
Deep-down below sessile invertebrates, such as sponges and tunicates hide away amongst the
holdfasts from predatory fish, sea stars and sea-urchins.
The magnitude in number of most individual kelps entwined together absorbs and weakens the power
of the strongest of currents and waves, protecting adjoining coastlines. Providing such a contrasting
environment frees the forest occupiers to go about their daily business, entertaining guests in the
holdfasts and flirting with each other amongst the fronds. To put this into context, imagine how it
feels walking home from the pub on a really windy night compared to a calm, moonlight sky.
Now for the Chemistry Part!!!
Atmospheric CO2 is absorbed by seawater, across a thin boundary layer on the surface and, dissolves
into an aqueous form. Almost 99% of this reacts with seawater, creating destructive carbonic acid
which, luckily, rapidly splits apart into 2 types of dissolved inorganic carbon, that are freely available
as the building blocks of sea life and, free Hydrogen ions. Hydrogen bicarbonate, as in bicarbonate of
soda, accounts for 90% of this dissolved inorganic carbon and,
carbonate the remainder.
For life to survive in the ocean, the chemical make-up of seawater
has to be at an optimum acid-alkaline balance. This is controlled by
seawater’s innate buffering capacity, known as alkalinity, which
resists changes in balance. This is measured by pH, which is the
negative logarithmic value of unattached, free Hydrogen ion
concentration. Optimum pH is around 8.2, so to maintain this level,
the addition of CO2 as Hydrogen Bicarbonate and Carbonate, is
balanced by equivalent amounts of free Hydrogen ions. As the
Image by Vancouver Aquarium
Image by Author

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amount of free Hydrogen ions increases pH levels drop, seawater becomes more acidic/less alkaline,
like bleach and this is where kelps help.
Different species of kelp take up Hydrogen Bicarbonate by a variety of different methods, known as
carbon concentrating mechanisms, and, inside their cells, convert this to Carbon Dioxide using an
enzyme known as Carbon Anhydrase says Pamela Fernandez. In the presence of sunlight, the Carbon
Dioxide is converted into Lucozade-like energy, glucose, releasing Oxygen into the seawater for fish
and animals to breath, just as we do. Whilst calcareous animals, such as crabs, snails and sea urchins,
and microscopic plankton that float around at the surface, make use of the available carbonate to
form their protective shells and plates.
Ocean Acidification – Climate Change’s Evil Twin
When the amount of CO2, dissolved into the water, exceeds the rate at which oceanic chemical
reactions can occur, it becomes so saturated, that excess free hydrogen ions form increasing amounts
of destructive carbonic acid, the equivalent of battery acid on our skin. As the protective shell coats
of animals are dissolved by this battery acid, the weaker they become to the environment and, more
easily consumed by predators, similar to how Coca-Cola dissolves aged dirt on coins.
Over the past 200 years to 2000 atmospheric CO2 increased, by a very high 33% to 360 ppm (parts per
million), amounting to 0.17% per year. Since
2000, monitoring records at the Scripts
Institute of Oceanography, Mauna Loa on the
idyllic islands of Hawaii, show current
atmospheric CO2 has increased, by a further
15%, to over 400 ppm or 0.94% per year. This
equates to an anxiously astonishing rate of
increase, between pre-2000 and 2016 of 73%.
At the same time, free Hydrogen ion
concentrations have increased, by 32%
between the 1800s and 2000, a rate of 0.16%
per year. This is predicted to increase by a total
of 70% in 2050 and a total of 130% by 2100, i.e.
at a rate of 1.4% per year says Dr. Ken Caldeira. This amounts to an increase, in the rate of Hydrogen
Ion concentration released into the ocean, of 8.75% between pre-2000 and 2050. “By 2050 we will be
Image by Katharina Fabricus

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in unknown territory, as pH levels are predicted to be lower, than at any point in the past 25 million
years” says Prof. Jason Hall-Spencer, a pioneer of research into the effects of ocean acidification at
natural CO2 seeps.
However, it is not necessarily as bad a situation as it could be, since there are winners and losers in all
walks of life. Excess CO2 is a great treat for photosynthetic algae and kelps, that take it up like it’s gold
dust, increasing their growth and primary production, as well as seawater alkalinity. On the other side
of the coin though, this lowers the availability of carbonate for animals using calcium carbonate, to
form their protective coatings and shells. But, due to the enormous density of kelp in these forests,
the amount of Hydrogen Bicarbonate they are able to absorb, can keep pH at normal levels during
daytime. Thus allowing animals to form their shells, as shown by Dr. Bruno Delille, who observed in
the sub-Antarctic, a 1.6% increase in seawater pH inside the forest, compared to outside.
Too hot to handle
Add to this seawater boiling away in a saucepan and, a
recipe for disaster begins to emerge, as our insatiable
desire for fossil fuels continues. The unstoppable rise of
greenhouse gases projected into the atmosphere creates
“radiative forcing”. Solar energy that is not absorbed by the
planet, is rebounded back into the stratosphere, becoming
trapped, known as “the greenhouse effect”. Like a mirror,
the stratosphere reflects back this extra solar energy,
accumulating heat and rising the planet’s temperature.
Just like ourselves being stuck in a sunlit office devoid of
open windows all day, kelp become stressed and over-
heated, by temperatures higher than their normal range of
5-20o
C, depending on the particular species. This causes a
loss of their defence chemicals and pigments, similar to
melatonin which we rely upon to defend our skin against sunburn, frizzling their fronds, that inhibits
their photosynthetic working capacity.
Extreme elevated temperature events, also known as “El Nino” and “El Nana” years, are increasing in
number. As Dr. Dan Smale says temperature increases of 2-4o
C, a 7.8-16% increase above the ~20o
C
norm in Australia, 5 years ago, are increasing. Curtailing regions in which Kelp Forests can occupy,
Image by Sandy Didine

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both now and in the future. Dr. Juliet Brodie has pointed out that the warming of the NE Atlantic alone,
is already causing a poleward shift, of species adapted to cooler waters of below 13o
C, such as
Laminaria hyperborea and L. digitata. Along the eastern coast of the Pacific Ocean, in the sunshine
state of California, only a 3o
C rise in temperature is enough to reduce growth in the giant kelp,
Macrocystis pyrifera, says Matthew Brown. However, ironically, he goes on to say that, when coupled
with increased CO2, the opposite occurs.
Wild as the Wind
Increasing storms, such as
Hurricane Katrina, add to the
vulnerability of Kelp Forests. On
the one hand, kelp forests require
a certain degree of wave and
current flow, to remove sediment
from blocking the sunlight they
need to photosynthesise. Dr. Dan
Smale has shown that, in the “wild
west” of the Northern Scottish
Isles, an increase in wave speed of
an astonishing 538%, from 0.16 to
1.02 meters per second, has a profound effect. The number of individual L. hyperborea per square
meter rose dramatically, by 66% from six to ten and, like a runaway train, frond length increased by
41% from 1.7 to 2.4 meters.
Along the western and southern coasts of the UK L. digitata and L. hyperborea entwine together, but
epiphytic animals and algae are discerning in their choice of stipe. They choose the sandpaper surface
of that of L. hyperborea, to which they can form an attachment, as oppose to the smooth, glossy
surface of L. digitata. But with this comes at a price. L. hyperborea snaps as waves crash down, unable
to cope with the pressure, whereas the flexibility of L. digitata can absorb this. The result: an epiphytic
habitat lost, forever, as it is washed upon the shoreline, leaving broken L. hyperborea fronds floating
amongst the surface.
Image by www.boatus.com

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The UK is not unique for this. All over the world increasing hurricanes are decimating and, destroying
our underwater magical forests. Only to be replaced by rocks and boulders, smothered with slimy,
gruesome, turfing green algae, that provides no protection for animals, fish and our coastlines.
The Future?
The pernicious cocktail of ocean
acidification, increased warming
and strengthening storms is
placing one of the few jewels
left of our oceanic world in
jeopardy. Now is the time to act.
To protect these forests that
provide a healthy ecosystem, a
storage for excess CO2 and a
habitat abounding with an array
of exquisite micro and macro-
animals, fish and algae.
Deforestation has already wiped
out kelp in Canada, California,
Central and South America, not
to mention Europe, Japan and
Australasia. If we do not act
now, to reduce our unnecessary,
excessive use of fossil fuels, we
risk losing even more
environments which they
occupy, to invasive, non-native, competitive species, as suitably climatic areas become more and more
constricted. We have a choice now, we have a chance to turn things round, a challenge to act against
the greatest threat mankind has ever known. Let’s take that chance to better the future for our
children and their children and the planet they inherit from us.
Matthew Brown is a researcher at the Department of Biology, San Diego State University, San Diego, California, USA.
Dr. Ken Caldeira is a senior scientist at Carnegie Institution for Science (Global Ecology), Stanford, California, USA researching
issues related to climate, carbon, and energy.
Dr. Bruno Delille is a Research Associate at FRS-FNRS Chemical Oceanography Unit, University of Liège, Liège, Belgium.
Pamela Fernandez is a PhD student in the Department of Botany, University of Otago, New Zealand.
Image by Lynn Lee

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Prof. Jason Hall-Spencer is a Professor of Marine Biology at the University of Plymouth, UK, Editor-in-Chief of Regional Studies
in Marine Science, a UK Government Scientific Advisor on Marine Conservation Zones and serves on the Ocean Acidification
International Reference User Group.
Dr. Juliet Brodie is a Research Phycologist at the Department of Life Sciences, Natural History Museum, London
Dr. Dan Smale is a benthic marine ecologist and Research Fellow at the Marine Biological Association of the UK.
Prof. Robert S. Steneck is a Professor in the structure and function of coastal marin2e ecosystems at the University of Maine,
USA.