- The North Sea is undergoing "ecological meltdown"
as a result of global warming, according to startling new research. Scientists
say that they are witnessing "a collapse in the system", with
devastating implications for fisheries and wildlife.
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- Record sea temperatures are killing off the plankton
on which all life in the sea depends, because they underpin the entire
marine food chain. Fish stocks and sea bird populations have slumped.
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- Scientists at the Sir Alistair Hardy Foundation for Ocean
Science in Plymouth, which has been monitoring plankton in the North Sea
for over 70 years, say that an unprecedented heating of the waters has
driven the cold-water species of this microscopic but vital food hundreds
of miles to the north. They have been replaced by smaller, warm-water species
that are less nutritious.
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- "A regime shift has taken place and the whole ecology
of the North Sea has changed quite dramatically", says Dr Chris Reid,
the foundation's director. "We are seeing a collapse in the system
as we knew it. Catches of salmon and cod are already down and we are getting
smaller fish.
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- "We are seeing visual evidence of climate change
on a large-scale ecosystem. We are likely to see even greater warming,
with temperatures becoming more like those off the Atlantic coast of Spain
or further south, bringing a complete change of ecology.
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- "Some of the colder-water fish species that people
like to have with chips are at the southern limit of their range, and if
the warming trend continues, cod are likely to become extinct in the North
Sea in the next few decades."
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- This year stocks of young cod were at their lowest for
20 years. The numbers of wild salmon have almost halved over the past two
decades and this year the numbers returning to British rivers to spawn
fell to a record low. Meanwhile, warm-water fish such as red mullet, horse
mackerel, pilchards and squid are becoming increasingly common.
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- Overfishing has played a part in the decline, but scientists
have been surprised to see that stocks have not made their expected recovery
after severe cuts in fishing quotas. They say that continued warming will
effect all forms of marine life, including seabirds and dolphins.
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- Research by the Royal Society for the Protection of Birds
has established that seabird colonies off the Yorkshire coast and the Shetlands
this year suffered their worst breeding season since records began, with
many simply abandoning nesting sites.
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- The society puts it down to a record slump in sand eels,
which normally breed in their millions, providing the staple diet for many
seabirds and large fish. The eels depend on the plankton that are now being
pushed out by the warming waters.
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- The survey concentrated on kittiwakes, but other species
that feed on the eels, including puffins and razorbills, are also known
to be seriously affected. Dr Euan Dunn of the RSPB said last week: "We
know that sand eel populations fluctuate and you do get bad years. But
there is a suggestion that we are getting a series of bad years, and that
suggests something more sinister is happening."
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- He too pointed the finger at global warming and added:
"Everything points to the conclusion that there are major ecological
changes going on in the North Sea."
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- Plankton
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- Microscopic creatures found in their billions in every
square foot of sea. As the base of the marine food chain, they are vital
to young cod, salmon and sand eels. As North Sea temperatures have risen,
cold-water plankton have moved hundreds of miles to the north, disrupting
ecology. Warmer-water species tend to be smaller and less nutritious.
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- Crustaceans
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- Crab and lobster fisheries are thriving in the warmer
water around the UK and on warm-water plankton which have taken the place
of cold-water species.
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- Sea birds
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- An RSPB survey this summer shows east coast colonies
of kittiwakes, guillemots, puffins and razorbills had the worst breeding
season on record. Nest counts in east Yorkshire and Shetlands show kittiwakes
not laying or hatching eggs because of a severe shortage of their favourite
food - sand eels. Some colonies have even been abandoned.
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- Seals
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- Populations of common seal were hit in the late Eighties
by viral infection. Numbers had almost recovered when they were hit by
a second outbreak last winter. Both viral outbreaks coincided with influxes
of warm Atlantic water into the North Sea, and some scientists believe
that two events might be linked.
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- Salmon
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- Numbers estimated to have almost halved in 20 years,
and this year adults returning to UK rivers fell to a new low. Studies
show salmon are highly dependent on plankton on their journey to feeding
grounds in the north Atlantic.
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- Mediterranean fish
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- As seas have warmed, large numbers of Mediterranean species,
such as red mullet, squid and sardine, have moved into UK waters. Red mullet,
popular in Spain and France, are now being caught commercially in the North
Sea. In the Channel there are emerging sardine fisheries.
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- Sand eels
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- Make up between a third and half of the weight of all
fish in the North Sea. Caught in huge quantities by Danish factory ships,
which turn them into food pellets for pigs and fish. This summer, the Danish
fleet caught only 300,000 tonnes out of its 950,000-tonne quota - a record
low.
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- Cod
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- Stocks of young cod this year at their lowest for 20
years. Waters around the UK are the southern limit of their range. The
International Council for the Exploration of the Seas says numbers are
lower than previously thought, and has called for a ban on cod fishing
in the North Sea and Irish Sea.
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- © 2003 Independent Digital (UK) Ltd
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- http://news.independent.co.uk/uk/environment/story.jsp?story=454828
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