70
R.H. Charlier and Th. Lonhienne
observation of the problem, as is still occasionally expounded, and the
time has probably come for a coordinated European policy (Ministere
de l'Environnement France 1987).
It has been established that human activities and climatic modifications are leading causes of eutrophication and of the ensuing "green
tides". Little, if anything, can be done about weather and climate. Notwithstanding sustained campaigns in favor of and pious promises to
implement measures for environmental clean up and pollution abatement, it is highly improbable that discharges of domestic and industrial
wastes will be so reduced that enrichment of the coastal waters in phosphates and nitrates will be eradicated. And yet it has been shown that
river sand streams are the major nutrient contributors, particularly in
the Baltic area where used water treatment drastically reduced phosphate
discharge into the sea. Consequently, steps must be taken to approach
the problem differently.
Toxic algal blooms have been reported in water masses with high
nutrient and high irradiance levels, but the role of eutrophication is
questioned (Smayda 1989). A reduction in the quantity of nutrients will
not affect fish productivity, but rather that of filter feeders. Quantity and
quality of nutrients delivered to the coastal zone depend strongly on the
retention capacity of the river system, which is itself largely affected by
land use and management of the watershed (Billen 1991a,b).
Bioconversion has been frequently suggested as a remedy for the accumulation of algae, as mentioned above. Indeed, it is important for the
development of seaweed cultivation on an industrial scale, it can playa
far from negligible role in the production of needed organic fertilizers,
and it is a weapon against eutrophication. Yet, commercialization entails
may aleas: if one were to consider economic exploitation of the strandings on the coasts of Brittany, one would be faced with an investment
with a return time of 10 years. Leaving natural production, for cultivation it was once estimated that kelp farms along the Californian coast
. covering 400000 ha (10 6 acres) could gross 0.2 quad of energy. However,
the degree of uncertainty ranges from 0.1 to 10 times a given estimate
(Jackson and North 1973). The net energy recovered is, according
to some researchers, only a small fraction of the crop energy content
(Charlier 1991).
Bioconversion appears well adapted for treating the proliferating algal
biomass, for seaweeds (cultivated or harvested), for purifying the environment or for eliminating nutrients from waste waters.
No matter what the primary utilization of a coastal zone, attempts
must be made to reduce and control the agents bringing about eutrophication. This entails a coastal management plan on a national scale, which
R.H. Charlier and Th. Lonhienne
observation of the problem, as is still occasionally expounded, and the
time has probably come for a coordinated European policy (Ministere
de l'Environnement France 1987).
It has been established that human activities and climatic modifications are leading causes of eutrophication and of the ensuing "green
tides". Little, if anything, can be done about weather and climate. Notwithstanding sustained campaigns in favor of and pious promises to
implement measures for environmental clean up and pollution abatement, it is highly improbable that discharges of domestic and industrial
wastes will be so reduced that enrichment of the coastal waters in phosphates and nitrates will be eradicated. And yet it has been shown that
river sand streams are the major nutrient contributors, particularly in
the Baltic area where used water treatment drastically reduced phosphate
discharge into the sea. Consequently, steps must be taken to approach
the problem differently.
Toxic algal blooms have been reported in water masses with high
nutrient and high irradiance levels, but the role of eutrophication is
questioned (Smayda 1989). A reduction in the quantity of nutrients will
not affect fish productivity, but rather that of filter feeders. Quantity and
quality of nutrients delivered to the coastal zone depend strongly on the
retention capacity of the river system, which is itself largely affected by
land use and management of the watershed (Billen 1991a,b).
Bioconversion has been frequently suggested as a remedy for the accumulation of algae, as mentioned above. Indeed, it is important for the
development of seaweed cultivation on an industrial scale, it can playa
far from negligible role in the production of needed organic fertilizers,
and it is a weapon against eutrophication. Yet, commercialization entails
may aleas: if one were to consider economic exploitation of the strandings on the coasts of Brittany, one would be faced with an investment
with a return time of 10 years. Leaving natural production, for cultivation it was once estimated that kelp farms along the Californian coast
. covering 400000 ha (10 6 acres) could gross 0.2 quad of energy. However,
the degree of uncertainty ranges from 0.1 to 10 times a given estimate
(Jackson and North 1973). The net energy recovered is, according
to some researchers, only a small fraction of the crop energy content
(Charlier 1991).
Bioconversion appears well adapted for treating the proliferating algal
biomass, for seaweeds (cultivated or harvested), for purifying the environment or for eliminating nutrients from waste waters.
No matter what the primary utilization of a coastal zone, attempts
must be made to reduce and control the agents bringing about eutrophication. This entails a coastal management plan on a national scale, which