The British Isles
245
central role in the nitrogen cycle, providing a transfer mechanism for
nitrogen and carbon from the water column onto the mudflats.
Additional problems are also encountered when the algal mats become
detached from the surface of the mudflats. For example, sometimes they
occur as large drifting mats (Anonymous 1976a) which can interfere with
boating activities (Montgomery et al. 1985) and when subsequently cast
upon the shore as the so-called "green tides" usually during autumn
gales, they can accumulate in large quantities (Cotton 1911; Jeffreyet al.
1992) lowering the aesthetic quality of bathing beaches (Wilson et al.
1990; Jeffrey et al. 1992). Noxious smells caused by their decomposition
have also been reported, both locally in the bays/harbours (Cotton 1910,
1911; Letts and Richards 1911; Perkins and Abbott 1972; Southgate 1972;
Fletcher 1974; Montgomery and Soulsby 1980; Montgomeryet al. 1985;
den Hartog 1994), and in the vicinity of refuge dumps where the beach
casts are sometimes deposited (Fletcher 1974). There have also been reports of algal mats blocking power station intake ducts (Southgate 1972)
and, during decomposition on the beaches, encouraging swarms of
flies (Anonymous 1987; 1988) and blackening the lead-based paints on
boats and houses due to the presence of hydrogen sulphide (Cotton 1910,
1911).
The main "treatment" method usually involves removal of troublesome deposits, especially from recreational beaches (Fletcher 1974;
Anonymous 1987, 1988; Jeffrey et al. 1972); at Worthing, on the south
coast of England, it was suggested that assistance be given to the
"natural" removal of seaweed, involving modifications to groynes and
pushing the seaweed down the shingle in reach of the tides (Anonymous
1987, 1988). In some situations, the effluent load is either diverted away
(Soulsbyet al. 1985) or longer outfall pipes are used (Anonymous 1976a;
Ford et al. 1983). Previous considerations given to the chemical treatment of the algae have not been implemented on environmental grounds
(Cotton 1911; Anonymous 1976a). Whilst it is widely considered that
long term treatment will require a reduction in the levels of nutrients
being discharged into nearshore waters and this is already receiving
attention at some sites (e.g partial nutrient removal is underway in
Langstone Harbour; Ford et al. 1983), this is expensive and would be
difficult in the case of diffuse sources via river runoff (Wilson et al. 1990).
There is also growing evidence that any changes made in the
concentrations of nutrients being released might not necessarily
be reflected in seaweed growth patterns (Anonymous 1976a; Soulsby
et al. 1985). Clearly, there is an urgent need for more detailed studies to
be carried out on the relationship between nutrient inputs and the occurrence of excess algal growths at the various sites affected and such needs
245
central role in the nitrogen cycle, providing a transfer mechanism for
nitrogen and carbon from the water column onto the mudflats.
Additional problems are also encountered when the algal mats become
detached from the surface of the mudflats. For example, sometimes they
occur as large drifting mats (Anonymous 1976a) which can interfere with
boating activities (Montgomery et al. 1985) and when subsequently cast
upon the shore as the so-called "green tides" usually during autumn
gales, they can accumulate in large quantities (Cotton 1911; Jeffreyet al.
1992) lowering the aesthetic quality of bathing beaches (Wilson et al.
1990; Jeffrey et al. 1992). Noxious smells caused by their decomposition
have also been reported, both locally in the bays/harbours (Cotton 1910,
1911; Letts and Richards 1911; Perkins and Abbott 1972; Southgate 1972;
Fletcher 1974; Montgomery and Soulsby 1980; Montgomeryet al. 1985;
den Hartog 1994), and in the vicinity of refuge dumps where the beach
casts are sometimes deposited (Fletcher 1974). There have also been reports of algal mats blocking power station intake ducts (Southgate 1972)
and, during decomposition on the beaches, encouraging swarms of
flies (Anonymous 1987; 1988) and blackening the lead-based paints on
boats and houses due to the presence of hydrogen sulphide (Cotton 1910,
1911).
The main "treatment" method usually involves removal of troublesome deposits, especially from recreational beaches (Fletcher 1974;
Anonymous 1987, 1988; Jeffrey et al. 1972); at Worthing, on the south
coast of England, it was suggested that assistance be given to the
"natural" removal of seaweed, involving modifications to groynes and
pushing the seaweed down the shingle in reach of the tides (Anonymous
1987, 1988). In some situations, the effluent load is either diverted away
(Soulsbyet al. 1985) or longer outfall pipes are used (Anonymous 1976a;
Ford et al. 1983). Previous considerations given to the chemical treatment of the algae have not been implemented on environmental grounds
(Cotton 1911; Anonymous 1976a). Whilst it is widely considered that
long term treatment will require a reduction in the levels of nutrients
being discharged into nearshore waters and this is already receiving
attention at some sites (e.g partial nutrient removal is underway in
Langstone Harbour; Ford et al. 1983), this is expensive and would be
difficult in the case of diffuse sources via river runoff (Wilson et al. 1990).
There is also growing evidence that any changes made in the
concentrations of nutrients being released might not necessarily
be reflected in seaweed growth patterns (Anonymous 1976a; Soulsby
et al. 1985). Clearly, there is an urgent need for more detailed studies to
be carried out on the relationship between nutrient inputs and the occurrence of excess algal growths at the various sites affected and such needs