Shelf Seas

What are shelf seas?

The term “Shelf Seas” or “Shallow Seas” refers to the ocean waters over the continental shelf under 200m depth.

The movement of these waters is controlled by the combined influences of the tides, wind & currents, and river inflows.

Some Facts on Shelf Seas…

Shelf seas are arguably the most important part of our ocean systems – providing society with a wide range of extremely valuable ecosystem services – like fisheries.
  • Shelf seas cover about 7% of the global surface area of the oceans.
  • However – the the UK coast is characterised by shelf seas – with approximately 78% of UK waters being shelf seas.
  • Shelf seas are highly productive compared to the open ocean, supporting more than 90% of global fisheries.
Image: National Oceanography Centre

A deep dive into shelf seas

Shelf seas are extremely valuable in terms of their biodiversity, capacity for carbon cycling & storage, ability to recycle nutrients and eliminate wastes and toxins, availability for recreation and leisure activities, and potential for renewable energy.

Here are some interesting facts….

  • Nutrients – such as nitrate, phosphate, silicate, and iron – enter the marine system through riverine inputs into shelf seas. This creates  conditions for primary production – i.e. the growth of microscopic marine plants – providing the basis of the food web and supporting fisheries.
  • The interaction between the water and shallow seabed allows nutrients, carbon and contaminants to be deposited and stored in the sediments on the seafloor, or recycled and released to stimulate water column productivity.
  • In shallow seas, mixing of the water column is driven by tides, winds, changes in temperature, and freshwater inputs. Frequent mixing leads to pulses in productivity – sustaining healthy fisheries!
  • The water column interacts with the seafloor to determine the physical properties of the seabed. Creating  a mosaic of different habitats, from fine muds to coarse sands or boulders and rocks, with associated diverse biological communities.

Want to find out more?

Take a sneak peek at our Shelf Seas lecture slides

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