30
R.L. Fletcher
potential utilization of the algal biomass obtained. For example,
consideration is being given to anaerobic digestion processes to produce
biogas (Wise et al. 1979; Habig et al. 1984; Croatto 1985; Missoni and
Mazzagardi 1985; Nicolini and Viglia 1985; DeBusk et al. 1986; Briand and
Morand 1987; Frederiksen 1987; Rigoni et al. 1989), aerobic digestion
processes to produce soil compost (Gladstone and Lopez-Real 1993; Maze et al.
1993), use as animal/human feed (Bonalberti and Croatto 1985) and the
industrial extraction of fine chemicals, lectins, polysaccharides, B-carotene etc.
Other control methods which have been considered include:
(1) improving water circulation and current flow and thereby, preventing
the build up of nutrients (Buttermore 1977);
(2) lowering the salinity of the contaminated waters by controlled
freshwater influx in order to kill the algae (Buttermore 1977);
(3) removal of nutrients from effiuents at the tertiary sewage treatment stage
or at least regulating the nutrient composition to produce an effiuent less
favourable to algal growth (Frederiksen 1987; Bokn et al. 1992). Nutrient
extraction and regulation is, however, an expensive process and would
not be appropriate in regions where the nutrient loading was derived
principally from agricultural runoff (e.g. 80% of nitrogen entering
Odense Fjord, Denmark; Frederiksen 1987) or if the bulk of nutrients is
from diffuse sources via river run-off (Wilson et al. 1990); the latter
would require long-term reductions in the use of fertilizers.
One interesting prospect is the removal of nutrients by mariculture
techniques. For example, Merrill (1994) and Merrill and Fletcher (1991)
suggest that eutrophicated regions could provide suitable conditions for
the commercial production of economically important species.
References
Alfimov NN (1959) Methods of hydrobiological analysis of the sanitary quality of littoral
seawater. Tr V ses gidrobiol Obua 9: 360-366
Anderson M (1942) Einige ernahrungsphysiologische Versuche mit Ulva und Enteromorpha. K Fysiogr Sallsk Lund Forh 12: 42-52
Aneer G (1987) High natural mortality of Baltic herring (Clupea harengus) eggs caused by
algal exudates? Mar BioI 94: 163-169
Anonymous (1973) Environmental study of Port Phillip Bay. Report on Phase One
1968-1971. Melbourne, 372pp
Anonymous (1976a) Langstore Harbour Study- the effect of sewage effluent on the ecology
of the harbour. Rep to Southern Water Authority. Portsmouth Polytechnic, Portsmouth,
356pp
R.L. Fletcher
potential utilization of the algal biomass obtained. For example,
consideration is being given to anaerobic digestion processes to produce
biogas (Wise et al. 1979; Habig et al. 1984; Croatto 1985; Missoni and
Mazzagardi 1985; Nicolini and Viglia 1985; DeBusk et al. 1986; Briand and
Morand 1987; Frederiksen 1987; Rigoni et al. 1989), aerobic digestion
processes to produce soil compost (Gladstone and Lopez-Real 1993; Maze et al.
1993), use as animal/human feed (Bonalberti and Croatto 1985) and the
industrial extraction of fine chemicals, lectins, polysaccharides, B-carotene etc.
Other control methods which have been considered include:
(1) improving water circulation and current flow and thereby, preventing
the build up of nutrients (Buttermore 1977);
(2) lowering the salinity of the contaminated waters by controlled
freshwater influx in order to kill the algae (Buttermore 1977);
(3) removal of nutrients from effiuents at the tertiary sewage treatment stage
or at least regulating the nutrient composition to produce an effiuent less
favourable to algal growth (Frederiksen 1987; Bokn et al. 1992). Nutrient
extraction and regulation is, however, an expensive process and would
not be appropriate in regions where the nutrient loading was derived
principally from agricultural runoff (e.g. 80% of nitrogen entering
Odense Fjord, Denmark; Frederiksen 1987) or if the bulk of nutrients is
from diffuse sources via river run-off (Wilson et al. 1990); the latter
would require long-term reductions in the use of fertilizers.
One interesting prospect is the removal of nutrients by mariculture
techniques. For example, Merrill (1994) and Merrill and Fletcher (1991)
suggest that eutrophicated regions could provide suitable conditions for
the commercial production of economically important species.
References
Alfimov NN (1959) Methods of hydrobiological analysis of the sanitary quality of littoral
seawater. Tr V ses gidrobiol Obua 9: 360-366
Anderson M (1942) Einige ernahrungsphysiologische Versuche mit Ulva und Enteromorpha. K Fysiogr Sallsk Lund Forh 12: 42-52
Aneer G (1987) High natural mortality of Baltic herring (Clupea harengus) eggs caused by
algal exudates? Mar BioI 94: 163-169
Anonymous (1973) Environmental study of Port Phillip Bay. Report on Phase One
1968-1971. Melbourne, 372pp
Anonymous (1976a) Langstore Harbour Study- the effect of sewage effluent on the ecology
of the harbour. Rep to Southern Water Authority. Portsmouth Polytechnic, Portsmouth,
356pp