24
R. L. Fletcher
shown to exert a preference for it over N0 3 , with the algae exhibiting faster
growth rates, rendering them particularly adaptable to sewage effiuent
(Letts and Richards 1911; Foster 1914; Wilkinson 1963; Waite and Mitchell
1972a; Waite et al. 1972; Harlin and Thorne-Miller 1981; Vandermeulen
and Gordin 1990). Certainly, it has been shown that Ulva can store
molecular nitrogen intracellularly, whilst Fujita et al. (1988) revealed it is
converted into macromolecular nitrogen. This stimulatory effect of
ammonia might well be related to the latter's ease of assimilation (Bongers
1956; Syrett 1962). It would also be advantageous to be capable of using
ammonia in late summer when nitrate is depleted (Prince and Kingsbury
1973; Topinka and Robbins 1976).
Also pertinent to this discussion are reports showing that a number of
genera such as Ulva, Corallina and Lithothrix have the ability to use
organic sources of nitrogen, either as the amide or amino group, including
urea, amino acids etc, and organic sources of carbon including acetate,
glucose etc. as a nutrient source. (Foster 1914; Fries 1963; North 1963;
Iwasaki 1967; Fries and Pettersson 1968; Nasr et al. 1968; Neish and Fox
1971; Mohsen et al. 1974; DeBoer et al. 1978; DeBoer 1981; Markager and
Sand-Jensen 1990; Park 1992). With the large quantities of soluble organic
compounds discharged into some inshore waters, North et al. (1972)
suggest that this organic waste may explain the excessive growths of some
algae reported. The rapid uptake systems in Ulva, Enteromorpha,
Lithothrix and Corallina were also considered by North et al. (1972) to be
partially responsible for the success of these algae in polluted
environments. They further point out that algae with little or no uptake
ability (fleshy brown and red algae) are conspicuously absent from
contaminated waters. For example, algae such as Ulva fasciata were shown
to exhibit higher growth rates when supplied with urea compared with
either NH4 or N0 3 (Mohsen et al. 1974; DeBoer 1981). Many of the organic
nitrogen sources are commonly discharged in sewage effiuent and it is
interesting to add that Ulva lactuca has been shown to take up acetate which
is a by-product of bacterial decomposition of organic matter (Gemmill and
Galloway 1974). Also pertinent is the report of Markager and Sand-Jensen
(1990) who revealed Ulva lactuca to grow significantly faster in cultures
supplied with glucose and acetate in the dark and/or dim light, explaining
its ability to adapt to prolonged periods of low light conditions and
maintain an intact photosynthetic apparatus. It has also been suggested
that this ability to take up organic substrates may explain Ulva's ability to
tolerate extended periods of burial (Vermaat and Sand-Jensen 1987). North
et al. (1972) also demonstrated that a very rapid uptake of organic
compounds occurred in Ulva and Enteromorpha, this being important
because of limited tidal cycle exposure. This ability to rapidly absorb
R. L. Fletcher
shown to exert a preference for it over N0 3 , with the algae exhibiting faster
growth rates, rendering them particularly adaptable to sewage effiuent
(Letts and Richards 1911; Foster 1914; Wilkinson 1963; Waite and Mitchell
1972a; Waite et al. 1972; Harlin and Thorne-Miller 1981; Vandermeulen
and Gordin 1990). Certainly, it has been shown that Ulva can store
molecular nitrogen intracellularly, whilst Fujita et al. (1988) revealed it is
converted into macromolecular nitrogen. This stimulatory effect of
ammonia might well be related to the latter's ease of assimilation (Bongers
1956; Syrett 1962). It would also be advantageous to be capable of using
ammonia in late summer when nitrate is depleted (Prince and Kingsbury
1973; Topinka and Robbins 1976).
Also pertinent to this discussion are reports showing that a number of
genera such as Ulva, Corallina and Lithothrix have the ability to use
organic sources of nitrogen, either as the amide or amino group, including
urea, amino acids etc, and organic sources of carbon including acetate,
glucose etc. as a nutrient source. (Foster 1914; Fries 1963; North 1963;
Iwasaki 1967; Fries and Pettersson 1968; Nasr et al. 1968; Neish and Fox
1971; Mohsen et al. 1974; DeBoer et al. 1978; DeBoer 1981; Markager and
Sand-Jensen 1990; Park 1992). With the large quantities of soluble organic
compounds discharged into some inshore waters, North et al. (1972)
suggest that this organic waste may explain the excessive growths of some
algae reported. The rapid uptake systems in Ulva, Enteromorpha,
Lithothrix and Corallina were also considered by North et al. (1972) to be
partially responsible for the success of these algae in polluted
environments. They further point out that algae with little or no uptake
ability (fleshy brown and red algae) are conspicuously absent from
contaminated waters. For example, algae such as Ulva fasciata were shown
to exhibit higher growth rates when supplied with urea compared with
either NH4 or N0 3 (Mohsen et al. 1974; DeBoer 1981). Many of the organic
nitrogen sources are commonly discharged in sewage effiuent and it is
interesting to add that Ulva lactuca has been shown to take up acetate which
is a by-product of bacterial decomposition of organic matter (Gemmill and
Galloway 1974). Also pertinent is the report of Markager and Sand-Jensen
(1990) who revealed Ulva lactuca to grow significantly faster in cultures
supplied with glucose and acetate in the dark and/or dim light, explaining
its ability to adapt to prolonged periods of low light conditions and
maintain an intact photosynthetic apparatus. It has also been suggested
that this ability to take up organic substrates may explain Ulva's ability to
tolerate extended periods of burial (Vermaat and Sand-Jensen 1987). North
et al. (1972) also demonstrated that a very rapid uptake of organic
compounds occurred in Ulva and Enteromorpha, this being important
because of limited tidal cycle exposure. This ability to rapidly absorb