The Marine Environment

  • Why is the sea blue and some seas bluer than others? The sea is blue because sea water absorbs all the different colours of light differently and scatters the blue light most and so we see the sea as blue

  • Why is sea water salty? The sea is salty because the rivers that flow into it wash salts and other minerals out of the ground. These dissolve in the rivers and the rivers then flow into the sea. Another source of salt is the sea bed. As the Sun evaporates the water from the sea to make clouds, it leaves the salts and minerals behind, so the sea is much saltier than rivers and lakes. Even though it rains on the sea as on land, this isn't enough to dilute the salt.
  • Three quarters of the earth is covered in water - more is known about outer space than the seas
  • 97% of the life on Earth is in the sea
  • The global abundance of cold water corals has only recently been discovered - the Darwin Mounds off NW Scotland are now a Special Area of Conservation
  • The greatest genetic resource on Earth is in the sea and there is more DNA in a bucket of seawater than in the human body

Page updated: Tuesday, March 20, 2012