Portugal
289
settlement of dense communities of the invasive Sargassum muticum in
large semi-open basins of sand and mud bottoms in the Minho coast
(north of Porto) has also been observed.
Changes in coastal benthic vegetation, possibly as a result of eutrophication, pollution or other man-made changes of the environment, have
also been observed for marine phanerogams. Several studies on saltmarsh ecosystems have been undertaken in lagoons and estuaries, and
settlements of halophilic communities have been observed and
described.
Moreira (1986) refers to the most important species found in coastal
lagoons and estuaries as Hamilione, Arthrocnemum and Juncus spp. in
upper salt marshes, and Spartina maritima in lower salt marshes. In the
Sado estuary and Faro lagoon, this last species is replacing the Chenopodiaceae as the sand covers muddy soils after dune erosion provoked
by man. Salines, rice fields and aquaculture units, as well as dredging,
sand extraction and pollution in several estuaries have disturbed and
modified the extension of the highly productive Spartina and Chenopodiaceae marshes (Moreira 1986). In the Tejo estuary, for example,
productivity was estimated as 700 and 350 million kcal m -2 year-I,
respectively (Catarino and Ramos 1981).
Ferreira and Ramos (1989) estimated an annual net production of 405,
213 and 67 g C m -2 year- 1 for Fucus vesiculosus, Ulva lactuca and
Gracilaria verrucosa, respectively, and a total algal estuarine gross
primary production of 5077 t C year-I.
Seagrasses (Zostera marina and Z. noltii) together with algae (mainly
Ulva, Enteromorpha, Fucus and Gracilaria spp.) colonize muddy surfaces
in most estuaries and lagoons. In some restricted interior areas
eutrophicated by urban and industrial waste discharge, mass development has occurred. In the most important estuaries and lagoons (Douro,
Ria de Aveiro, Tejo, Sado and Ria Formosa), however, the strong tidal
currents reduce or prevent serious eutrophication, which may explain
the lack of intensive studies on floristic changes in salt marshes in
relation to eutrophication.
At present, J.e. Marques and his team from Coimbra University are
studying structural dynamic models for estuarine ecosystems, together
with qualitative changes in macrophytes due to eutrophication in the Mira
and Mondego estuaries. They observed a progressive increase in
Enteromorpha spp. populations and biomass (4-5 kg m- 2 ), together with
the reduction in Zostera beds in the southern arm of the Mondego estuary
(pers. comm.).
Besides the observed effects of local eutrophication on benthic vegetation in the enclosed areas of some coastal areas, the phenomenon of red
289
settlement of dense communities of the invasive Sargassum muticum in
large semi-open basins of sand and mud bottoms in the Minho coast
(north of Porto) has also been observed.
Changes in coastal benthic vegetation, possibly as a result of eutrophication, pollution or other man-made changes of the environment, have
also been observed for marine phanerogams. Several studies on saltmarsh ecosystems have been undertaken in lagoons and estuaries, and
settlements of halophilic communities have been observed and
described.
Moreira (1986) refers to the most important species found in coastal
lagoons and estuaries as Hamilione, Arthrocnemum and Juncus spp. in
upper salt marshes, and Spartina maritima in lower salt marshes. In the
Sado estuary and Faro lagoon, this last species is replacing the Chenopodiaceae as the sand covers muddy soils after dune erosion provoked
by man. Salines, rice fields and aquaculture units, as well as dredging,
sand extraction and pollution in several estuaries have disturbed and
modified the extension of the highly productive Spartina and Chenopodiaceae marshes (Moreira 1986). In the Tejo estuary, for example,
productivity was estimated as 700 and 350 million kcal m -2 year-I,
respectively (Catarino and Ramos 1981).
Ferreira and Ramos (1989) estimated an annual net production of 405,
213 and 67 g C m -2 year- 1 for Fucus vesiculosus, Ulva lactuca and
Gracilaria verrucosa, respectively, and a total algal estuarine gross
primary production of 5077 t C year-I.
Seagrasses (Zostera marina and Z. noltii) together with algae (mainly
Ulva, Enteromorpha, Fucus and Gracilaria spp.) colonize muddy surfaces
in most estuaries and lagoons. In some restricted interior areas
eutrophicated by urban and industrial waste discharge, mass development has occurred. In the most important estuaries and lagoons (Douro,
Ria de Aveiro, Tejo, Sado and Ria Formosa), however, the strong tidal
currents reduce or prevent serious eutrophication, which may explain
the lack of intensive studies on floristic changes in salt marshes in
relation to eutrophication.
At present, J.e. Marques and his team from Coimbra University are
studying structural dynamic models for estuarine ecosystems, together
with qualitative changes in macrophytes due to eutrophication in the Mira
and Mondego estuaries. They observed a progressive increase in
Enteromorpha spp. populations and biomass (4-5 kg m- 2 ), together with
the reduction in Zostera beds in the southern arm of the Mondego estuary
(pers. comm.).
Besides the observed effects of local eutrophication on benthic vegetation in the enclosed areas of some coastal areas, the phenomenon of red