The Spanish Mediterranean Coasts
297
12.2 Green Algal Communities and Proliferation
A number of quantitative studies have been carried out on green algal
communities and their proliferation mainly on rocky shores. Ballesteros
(1992) related these not only to nutrient enrichments, but also to substrate instability. The presence and abundance of green algal communities is rather irregular, varying from site to site and from year to year
(Ballesteros 1989). Growth occurs throughout the year, but is frequently
and irregularly interrupted by disturbances, as for example storms or
persistent low see levels. Biomass values as high as 250 g dry weight m- 2
for Enteromorpha compressa, and 375 g dry weight m -2 for Ulva rigida
have been reported (sample size: 100-200 cm 2 ; Ballesteros 1992). Their
production values are from 0 to 4 gem -2 day-I as estimated by weekly
measurements (Perez 1984; Ballesteros 1992), and the average biomass
duplication time is 23 days (annual minimum 5 days). Yearly production
for E. compressa is around 100 g C m -2 year-I, and blade area index can
reach 10 (Ballesteros 1992). Such values seem to be high, but it should be
taken into account that this biomass accumulation is reached only in
small patchy areas (maximum 1 m 2 ) or in narrow vertical zones of less
than 0.5 m, which however, can extend horizontally for some tens of
meters. In addition, the communities referred to are on semi-exposed
rocky substrates, which means a certain degree of vertical structure,
along with movement of the thalli that prevents the self-shading caused
by blade accumulation (see Niell et a1., Chap. 10, this Vo1.).
The distribution of green algae such as Cladophora ssp., Ulva ssp. and
Enteromorpha ssp., and other "pioneering" species (Scytosiphon lomentaria, Codium fragile ssp. tomentosoides) was used as a quality indicator
in an extensive survey of the NE coast (Catalonia, > 600 km of coastline)
in summer 1982 (Ballesteros et a1. 1984). No massive green algal proliferations were reported, although in some coastal zones a dominance of
pioneering species was evident. Blade indices of ulvaceans were always
between 1 and 4. Green algae were also abundant inside some harbours
and marinas, but within the same range of biomass.
Macroalgal green tides along the Spanish Mediterranean coast have
not been reported during recent years, except for one area which is
described below. Even if the number of quantitative data and systematics
surveys supporting this contention is still low, it should be remembered
that there is a good knowledge of the qualitative aspects of the Mediterranean Spanish Flora (Gallardo et a1. 1985; Ribera et al. 1992; Gallardo
et al. 1993). A considerable number of phycologists working in this area
agree about the absence of green algal proliferation.
297
12.2 Green Algal Communities and Proliferation
A number of quantitative studies have been carried out on green algal
communities and their proliferation mainly on rocky shores. Ballesteros
(1992) related these not only to nutrient enrichments, but also to substrate instability. The presence and abundance of green algal communities is rather irregular, varying from site to site and from year to year
(Ballesteros 1989). Growth occurs throughout the year, but is frequently
and irregularly interrupted by disturbances, as for example storms or
persistent low see levels. Biomass values as high as 250 g dry weight m- 2
for Enteromorpha compressa, and 375 g dry weight m -2 for Ulva rigida
have been reported (sample size: 100-200 cm 2 ; Ballesteros 1992). Their
production values are from 0 to 4 gem -2 day-I as estimated by weekly
measurements (Perez 1984; Ballesteros 1992), and the average biomass
duplication time is 23 days (annual minimum 5 days). Yearly production
for E. compressa is around 100 g C m -2 year-I, and blade area index can
reach 10 (Ballesteros 1992). Such values seem to be high, but it should be
taken into account that this biomass accumulation is reached only in
small patchy areas (maximum 1 m 2 ) or in narrow vertical zones of less
than 0.5 m, which however, can extend horizontally for some tens of
meters. In addition, the communities referred to are on semi-exposed
rocky substrates, which means a certain degree of vertical structure,
along with movement of the thalli that prevents the self-shading caused
by blade accumulation (see Niell et a1., Chap. 10, this Vo1.).
The distribution of green algae such as Cladophora ssp., Ulva ssp. and
Enteromorpha ssp., and other "pioneering" species (Scytosiphon lomentaria, Codium fragile ssp. tomentosoides) was used as a quality indicator
in an extensive survey of the NE coast (Catalonia, > 600 km of coastline)
in summer 1982 (Ballesteros et a1. 1984). No massive green algal proliferations were reported, although in some coastal zones a dominance of
pioneering species was evident. Blade indices of ulvaceans were always
between 1 and 4. Green algae were also abundant inside some harbours
and marinas, but within the same range of biomass.
Macroalgal green tides along the Spanish Mediterranean coast have
not been reported during recent years, except for one area which is
described below. Even if the number of quantitative data and systematics
surveys supporting this contention is still low, it should be remembered
that there is a good knowledge of the qualitative aspects of the Mediterranean Spanish Flora (Gallardo et a1. 1985; Ribera et al. 1992; Gallardo
et al. 1993). A considerable number of phycologists working in this area
agree about the absence of green algal proliferation.