SUSTAINABILITY AND THE ENVIRONMENT: LIVING SEAS
nurseries for important commercial fish
stocks. But oysters today are struggling to
perform these roles because they have
been all but wiped from the wild.
A deadly combination of overfishing,
pollution and disease and has seen the
world lose 85 per cent of its oyster reefs.
For marine scientists the scale of this
depletion highlights the urgent need to
restore this almost-forgotten ecosystem. At
the University of Portsmouth, researchers
have embarked upon an ambitious project
to restore oyster reefs to the Solent and
provide a case study for similar restoration
programmes elsewhere. The 20-mile strait
between mainland England and the Isle of
Wight was once home to millions of native
oysters – in fact, it was once Europe’s
largest oyster fishery – but by 2013 was so
depleted that even collecting oysters from
the area had to be banned.
In 2017 a University of Portsmouth survey
of 300 seabed samples in three harbours
found just three native oysters. This echoed
the stock assessments by the Southern
Inshore Fisheries and Conservation Authority
(SIFCA) that set in motion a major recovery
programme – The Solent Oyster Restoration
Project, a collaboration with the Blue Marine
Foundation, 1851 Trust, MDL Marinas,
Ineos, and UK oyster fisheries. Led by Dr
Joanne Preston, the programme provides an
evidence-based strategy and cutting-edge
restoration science to restore a healthy reefs
ecosystem to Solent and UK waters.
To begin repopulating the strait, the
research team suspended oyster-filled cages
from pontoons. Oyster larvae produced
in what some journalists dubbed aquatic
‘love hotels’ – a nod perhaps to Aphrodite
– are now re-settling the seabed. This is
an achievement in itself, but showing just
how interconnected the marine web of life
is, their cages were promptly occupied by
other creatures. The team has discovered 95
species in the cages, including endangered
European eels. Data from the cage study
are now being used to recommend ways
for marinas around the country to become
involved in oyster restoration.
Oysters are coming home, and they are
saving our seas.
Ecosystem engineers
Dr Preston describes oysters as ‘ecosystem
engineers’, their reefs and beds contributing
substantially to inshore biodiversity by
providing protection and nursery grounds
for juvenile fish and other species.
Oyster reefs are ‘biogenic’, meaning
they are solid structures created by living
organisms; in this case by shells mounting
up as oysters die, and as new oysters
settle on each other. This creates a 3D
hard structure that supports a whole new
ecosystem.
The restoration project, begun in late
2016, hopes to
reseed the Solent
with millions of
oysters over the
next few years to
restore the the
native oyster’s role in
lifting and sustaining
ecosystem health,
increase biodiversity
and improve water
quality.
Dr Preston’s
research also covers
molecular ecology
and evolution, which
involves looking at
the DNA sequences
of organisms to
identify relationships.
“Organisms’ DNA tells
Ecosystems
provide us with
food, oxygenated
water, and other
natural resources
we humans
depend on. And
ecosystems
depend on
biodiversity.
– Joanne Preston
us what’s related and what isn’t, and we
use this to understand true biodiversity.
By pinpointing how much genetic variation
is out there, you can estimate how likely
those organisms can adapt and survive in
the future.
“Essentially, the less genetic variation,
robustness and resilience there is, the
higher the chance of extinction,” she says.
Dr Preston says overfishing has caused
the gene pool (or genetic diversity) of many
marine species to shrink. This includes
oysters and one of the concerns being
addressed by The Solent Oyster Restoration
Project is the level of genetic diversity
within the remaining population, and
whether the population is diverse enough
to enable the oysters to survive and adapt
to the changed marine environment there.
If the oyster populations cannot be
sustained, then multiple other species that
depend on oyster reefs for food and shelter
are also in trouble.
Dr Preston’s Portsmouth team works
closely with Southampton University, Essex
University, Heriot-Watt University, Roslin
Preserving the Mary Rose
Dr Joanne Preston isn’t just preserving marine
life. She has also used her expertise to stabilise
the remains of King Henry VIII’s warship,
the Mary Rose, when it was raised from the
Solent after hundreds of years underwater.
The struggle to preserve it has been
challenging.
Dr Preston explains that the Mary Rose
was producing tonnes of sulphuric acid due to
the oxidation of iron and sulphur in the wood
and bolts after being exposed to air again.
The acid was eating away at the ship and
had to be stopped. Dr Preston used her DNA
expertise to discover iron-oxidising bacteria
in the wood, along with acidophilic bacteria,
which live off the iron and sulphur.
“It took three months trying to get
environmental DNA out of one piece of
archaeological wood. After amplifying a
specific gene from all the microbes that were
inside the wood, I sequenced these to identify
what species were living there, as well as
growing microbes using microbiology culturing
techniques. We discovered several species of
iron and sulphur organisms present in the Mary
Rose, and tested ways of stopping them.”
For Dr Preston, variety is the spice of
scientific life: “I always recommend scientists
go off-piste and challenge themselves by
trying new areas of research and collaborating
with people in different fields. The Mary Rose
work opened up a whole new world for me in
terms of microbiology and microbial ecology,
and it feeds into my oyster restoration work.”
Institute, the Centre for Environment,
Fisheries and Aquaculture Science in the UK,
and other research partners across Europe to
achieve a Europe-wide restoration and revive
the lost memory of thriving oyster reefs in
this part of the world.
� www.nativeoysternetwork.org
www.noraeurope.eu
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Recommendation-Part-1.pdf
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