Wetlands by the coast
Drive along the Ferry Road and you will catch glimpses of one of the jewels of Studland: the 35 hectare freshwater lake known locally as Little Sea.
However, this is just the most eye-catching part of a much larger wetland system that dissects the dunes all the way up to Shell Bay.
As the dune ridges formed over the past 400 years, they blocked off large areas of water from the sea, and the rainwater that has flushed through these dune ‘slacks’ since then has gradually turned them from salt to fresh water.
Although the dunes have been here for centuries now, the wetlands are still adapting to them. As the sand continues to build up in Shell Bay and along the northern part of Studland Beach, it impedes the drainage of the marshes still further. Water levels in Little Sea and throughout the wetlands have risen by about half a metre since 1930.
Although Little Sea is still largely open water, most of the smaller and shallower dune slacks have become colonised by purple moor grass, bog myrtle and other specialist wetland plants and mosses, and they now form an intricate mosaic of reedbeds, swamps, wet grasslands and sallow-dominated wet woodland.
Many areas are almost impossible to access on foot, so as well as being home to a vast array of specialist plants and invertebrates they are sheltered refuges for birds and animals, from great white egret to otters and water voles.
They are also some of the best places to spot sika deer in Purbeck. These water loving animals originally came from Asia but now find a safe haven in Studland’s impenetrable marshes and wet woodlands.
Little Sea is an idyllic lake in a beautiful setting – but sadly it tells a tale of ecological decline.
Despite being internationally protected as one of the UKs largest oligotrophic low nutrient lakes, in the early 2000s a member of the public illegally introduced carp into the lake, and unintentionally started a chain of knock-on effects that we are still trying to rectify.
Within a few years these bottom-feeding fish churned up sediments that had remained undisturbed for decades and stripped the lake of its highly specialist and rare aquatic plants.
The nutrient status of the lake has changed, most of the overwintering birds have gone and the water – described as recently as 2006 as being “clear, faintly tea coloured” is now murky and thick with suspended matter.
The National Trust is currently embarking on a major project to remove the carp (between 2014 and 2015 we fished out more than 1,000 kg!) and are hopeful that over the next few years we will restore it to its former glory.