Whiteness Gap IPA

Location: North easterly tip of the Isle of Thanet, between Margate and Broadstairs.

Grid Reference: TR 394 710

Whiteness Gap IPA has been recognised as one of 165 Important Plant Areas in the UK.

The key features of this IPA are:

  • The species richness of marine algae in Littoral rock and other hard substrata
  • The coastal chalk reef and cave habitats around Thanet are very unusual. There is very little coastal chalk in Europe, but the UK has most of it and 20% of this can be found at Thanet.

    These shores are the longest continuous stretch of coastal chalk in Britain. The reefs of Thanet are the chalk rocks that extend out to sea and are encrusted with marine plants and animals. The chalk here is softer than other coastal chalk, and with other muddy sediments often makes the water very cloudy.

    Marine plants and animals are found in unexpected combinations with some rarities amongst them. Thanet’s many sea caves form the second most extensive chalk sea caves in Britain. Partially submerged they vary considerably in depth, height and aspect and hence in the algal communities present. Some caves extend for up to 30m into the cliffs and reach 6-10m in height, although many are much smaller.

    The reefs are encrusted with marine plants. The soft chalk and cloudy water means that marine plants and animals are found in combinations that are not found elsewhere: kelp seaweeds with rock boring marine shellfish and worms, red seaweed turfs and microscopic marine plants and lichens which form velvety bands on the chalk.

    There is an unusually rich littoral algal flora, essentially of chalk-boring algae, which may extend above high water mark into the splash zone in wave-exposed areas. The caves support very specialised algal and lichen communities which form distinct velvety orange, brown or black bands around the high water mark. Some of these are only found on the shaded damp walls and ceilings of the caves and include species such as Pseudendoclonium submarinum and Lyngbya spp., some of which were first described from Thanet and so far have not been found anywhere else in the world. Other species of particular interest are Pilinia rimosa, and Apistonema carterae.