Charmouth beach in Dorset, a popular destination for walkers and fossil hunters, is currently experiencing a noticeable proliferation of bright green gutweed, particularly near the mouth of the River Char. While the beach remains a busy hub, visitors are advised to heed local council warnings regarding potential E. coli contamination in the immediate vicinity of the river's outflow, despite the main bathing water being designated as safe.
The seaweed, scientifically known as Ulva intestinalis or grass kelp, is a common and harmless species found across UK shores. It's a fast-growing plant that flourishes in summer and provides shelter for tiny marine creatures, such as copepods, within its dense filaments. However, its significant abundance in specific areas of Charmouth beach is raising questions about local water quality.
Experts note that gutweed's growth can be artificially amplified by the presence of excess nutrients, often originating from sewage discharges and agricultural runoff. Observations indicate that the seaweed forms a dense, rippling 'mono-pelt' closer to the river mouth, becoming less dominant further west along the coastline. This natural distribution pattern suggests a higher concentration of these nutrients near the river's entry point into the sea.
Further along the beach, towards Bar Ledges, the gutweed begins to intermingle with a more diverse range of marine flora, including brown wrack, kelp, and red coral weed. These other species do not exhibit the same prolific response to elevated nitrogen levels, underscoring gutweed's role as a potential bio-indicator of nutrient enrichment in the marine environment.
The situation at Charmouth serves as a visible reminder of ongoing concerns regarding water quality in certain coastal areas across the UK. While local authorities work to ensure bathing water safety, the natural world itself can provide clear signals about environmental health, with the vibrant green of the gutweed telling its own story of the water it inhabits.