Advertisement
UK markets close in 2 hours 4 minutes
  • FTSE 100

    7,964.39
    +32.41 (+0.41%)
     
  • FTSE 250

    19,890.30
    +79.64 (+0.40%)
     
  • AIM

    743.76
    +1.65 (+0.22%)
     
  • GBP/EUR

    1.1692
    +0.0023 (+0.20%)
     
  • GBP/USD

    1.2638
    +0.0000 (+0.00%)
     
  • Bitcoin GBP

    56,124.40
    +909.76 (+1.65%)
     
  • CMC Crypto 200

    885.54
    0.00 (0.00%)
     
  • S&P 500

    5,250.18
    +1.69 (+0.03%)
     
  • DOW

    39,746.28
    -13.80 (-0.03%)
     
  • CRUDE OIL

    82.42
    +1.07 (+1.32%)
     
  • GOLD FUTURES

    2,228.00
    +15.30 (+0.69%)
     
  • NIKKEI 225

    40,168.07
    -594.66 (-1.46%)
     
  • HANG SENG

    16,541.42
    +148.58 (+0.91%)
     
  • DAX

    18,497.31
    +20.22 (+0.11%)
     
  • CAC 40

    8,216.81
    +12.00 (+0.15%)
     

The Five Key Threats Facing Depths Of The Sea

The oceans are the planet's life support system. Half the oxygen we breathe is produced by marine plankton. And one billion people depend on fish as their primary source of protein.

Yet the seas are in peril - and here are five reasons why.

1. Sea temperature

Climate change is affecting the oceans just as it affects the land.

Sea temperature has risen by 1C over the past 35 years. Coldwater fish species are migrating towards the Poles to keep cool.

But for coral reefs - home to a quarter of all marine life - it's a catastrophe. It's taken them to the very limit of the temperature they can tolerate.

ADVERTISEMENT

And in an El Nino year - as now - the reefs can get so stressed that they "bleach". The corals expel the symbiotic algae that normally live inside their tissues.

But without the algae, which provide their hosts with energy from sunlight, the corals will die in a matter of weeks. Only the ghostly white skeletons remain.

Some scientists suggest 40% of coral has been destroyed in the last three decades.

2. Acidification

Greenhouse gases also make the oceans more acidic.

Every day they absorb 22 million tonnes of carbon dioxide from the atmosphere.

That's 525 billion tonnes since the start of the industrial revolution.

Mixed with seawater the gas forms carbonic acid.

Since 1800, the acidity of seawater has increased by 30%.

And some computer models predict the acidity will increase another 150% by the end of the century.

A by-product of the rising acidity is a reduction in calcium carbonate dissolved in the water. Molluscs aren't able to build their hard shells without the mineral. And fragile branching corals are struggling to survive.

3. Plastics

Eight million tonnes of plastic rubbish is dumped in the oceans every year.

It never disappears; it's just broken down into ever smaller pieces by the action of sunlight and the churning waves.

More than five trillion pieces of plastic are in the world's oceans. Most are just millimetres across. Too small and too numerous to clean up.

Sea birds, turtles and fish mistake the plastic for food. It fills their stomachs until they starve to death.

4. Overfishing

Fish is the primary source of protein for one billion people.

Almost 80 billion kilograms of wildlife are removed from the seas each year.

And it's not sustainable.

Purse seine nets can catch hundreds of tons of fish in a single trawl. And "longlining" - with hooks stretched over a 100km line - can catch thousands of fish.

Scientists have warned that if stocks are depleted at the present rate, all fisheries will have collapsed by 2048. The fish simply can't breed fast enough for the population to survive.

5. Invasive species

The lionfish underlines just how damaging a species can be when it invades a new habitat.

It's normally found in the Pacific, but a small number have been released into the Atlantic - some believe by Hurricane Andrew smashing a Florida aquarium in 1992.

They are protected by poisonous spines and have no natural predators in their new home.

They've quickly spread from New York to South America and in some areas more than 1,000 can be found in every acre.

They have voracious appetites. Research shows one lionfish eats around 5,000 other fish every year, its stomach expanding up to 30 times its normal size to accommodate its enormous appetite.

And with each female laying 2 million eggs a year, lionfish quickly out-competes other predators to dominate coral reefs.