10
R.L. Fletcher
considered responsible for the expansion of Ulva on the mudflats in
Langstone Harbour, south coast of England (Lowthion et al. 1985). Finally,
it is perhaps pertinent here to report of larger enclosed bodies of water,
including the Mediterranean Sea (Bellan and Peres 1972), the northern
Adriatic Sea (Revelante and Gilmartin 1976; Justic 1987; Degobbis 1989;
Marchetti et al. 1989) and the Baltic (Dybern 1972; Fonselius 1972;
Cederwall and Elmgren 1980; Larsson et al. 1985; Bonsdorff et al. 1991)
becoming eutrophic.
1.3 Secondary Effects of Nutrient-Carrying Waters
Any consideration of the ecological impact of nutrients derived from these
anthropogenic sources, particularly those, for example, discharged with
sewage effluent, must take into account the effect of other potential
pollutants contained within the carrying waters (O'Sullivan 1971). Both
sewage effluent and agricultural runoff will contain fresh water, suspended
solids and biological waste material. In addition, sewage contains various
surfactants/dispersants and occasionally traces of heavy metals, whilst
agricultural runoff can include quantities ofherbicides/pesticides as well as
hydrocarbons originating from roads (Bell et al. 1989). Many of these
pollutants are known to exert a marked effect on marine benthic communities, particularly marine benthic algae. For example, suspended particulate
matter including organic material will increase the turbidity of the water,
with a concomitant reduction in light penetration (Bellamy and Whittick
1964; Bellamyet al. 1972; Bellan 1967b; O'Sullivan 1971; North et al. 1972).
The photosynthetic activity of benthic algae would thus be reduced
(O'Sullivan 1971) under conditions of high sediment loading and this could
prove limiting for some benthic algae, particularly those in the sublittoral
zone (Grenager 1957; Rueness 1973). For example, Burrows (1971) and
Burrows and Pybus (1970, 1971), revealed a critical light requirement for
gametophyte fertilization in Laminaria saccharina. Reported effects of
reduced light penetration due to pollutants include a decline in Fucus
biomass in Kiel Bight, Western Baltic (Vogt and Schramm 1991), the
absence of Fucus serratus in effluent receiving fjord waters in Norway
(Bokn 1979), a decline in Macrocystis beds in the vicinity of sewage outfalls
in California (Devinny and Volse 1978) and a restricted distribution of
Laminaria saccharina on the Northeast coast of England (Burrows and
Pybus 1970). Competitive advantage would also be given to low-lightadapted algae, as suggested, for example, for Phyllophora truncata,
R.L. Fletcher
considered responsible for the expansion of Ulva on the mudflats in
Langstone Harbour, south coast of England (Lowthion et al. 1985). Finally,
it is perhaps pertinent here to report of larger enclosed bodies of water,
including the Mediterranean Sea (Bellan and Peres 1972), the northern
Adriatic Sea (Revelante and Gilmartin 1976; Justic 1987; Degobbis 1989;
Marchetti et al. 1989) and the Baltic (Dybern 1972; Fonselius 1972;
Cederwall and Elmgren 1980; Larsson et al. 1985; Bonsdorff et al. 1991)
becoming eutrophic.
1.3 Secondary Effects of Nutrient-Carrying Waters
Any consideration of the ecological impact of nutrients derived from these
anthropogenic sources, particularly those, for example, discharged with
sewage effluent, must take into account the effect of other potential
pollutants contained within the carrying waters (O'Sullivan 1971). Both
sewage effluent and agricultural runoff will contain fresh water, suspended
solids and biological waste material. In addition, sewage contains various
surfactants/dispersants and occasionally traces of heavy metals, whilst
agricultural runoff can include quantities ofherbicides/pesticides as well as
hydrocarbons originating from roads (Bell et al. 1989). Many of these
pollutants are known to exert a marked effect on marine benthic communities, particularly marine benthic algae. For example, suspended particulate
matter including organic material will increase the turbidity of the water,
with a concomitant reduction in light penetration (Bellamy and Whittick
1964; Bellamyet al. 1972; Bellan 1967b; O'Sullivan 1971; North et al. 1972).
The photosynthetic activity of benthic algae would thus be reduced
(O'Sullivan 1971) under conditions of high sediment loading and this could
prove limiting for some benthic algae, particularly those in the sublittoral
zone (Grenager 1957; Rueness 1973). For example, Burrows (1971) and
Burrows and Pybus (1970, 1971), revealed a critical light requirement for
gametophyte fertilization in Laminaria saccharina. Reported effects of
reduced light penetration due to pollutants include a decline in Fucus
biomass in Kiel Bight, Western Baltic (Vogt and Schramm 1991), the
absence of Fucus serratus in effluent receiving fjord waters in Norway
(Bokn 1979), a decline in Macrocystis beds in the vicinity of sewage outfalls
in California (Devinny and Volse 1978) and a restricted distribution of
Laminaria saccharina on the Northeast coast of England (Burrows and
Pybus 1970). Competitive advantage would also be given to low-lightadapted algae, as suggested, for example, for Phyllophora truncata,