11 Portugal
J.C. OLIVEIRA and G. CABEGADAS
11.1 Introduction
Portuguese coastal waters, in spite of being subjected to considerable
inputs of organic matter and nutrients from different sources, generally
present acceptable environmental conditions.
The nutrients, nitrogen and phosphorus reaching the coastal waters
are mainly transported by rivers and by untreated or poorly treated
urban and industrial effluents from sources located along the coast. A
process of upwelling, temporarily occurring in the western coast, also
provides nutrients to the biologically productive coastal zone. Due to
hydrographic, geomorphological and climatic conditions, the Portuguese
coastal waters do not show permanent symptoms of eutrophication.
However, some estuaries and lagoons situated along the coast of
Portugal (Fig. 11.1) have very complex topographies, presenting interior
zones and enclosed arms, which show seasonal signs of eutrophication,
such as poor conditions of oxygenation, increasing nutrient levels and
development of large amounts of micro algae. In these areas, localized
proliferation of some macroalgae, mainly Ulva and Enteromorpha spp.
has been observed.
In general, they do not constitute a nuisance, except occasionally in
some aquaculture units and when close to beaches.
The vascular vegetation of salt-marshes is also disturbed, probably as
a result of human activities like waste discharges and dredging, as
indicated by changes in the distribution and abundance of the communities of Zostera and Spartina spp. and Chenopodiaceae.
Another indication for eutrophication or pollution in some localized
areas may be the occurrence of red tides along the Portuguese coast
during the past years.
Portuguese Institute of Marine Research, A V. Brasilia, 1400 Lisboa, Portugal
Ecological Studies, Vol. 123
Schramm/Nienhuis (eds) Marine Benthic Vegetation
© Springer-Vedag Berlin Heidelberg 1996
J.C. OLIVEIRA and G. CABEGADAS
11.1 Introduction
Portuguese coastal waters, in spite of being subjected to considerable
inputs of organic matter and nutrients from different sources, generally
present acceptable environmental conditions.
The nutrients, nitrogen and phosphorus reaching the coastal waters
are mainly transported by rivers and by untreated or poorly treated
urban and industrial effluents from sources located along the coast. A
process of upwelling, temporarily occurring in the western coast, also
provides nutrients to the biologically productive coastal zone. Due to
hydrographic, geomorphological and climatic conditions, the Portuguese
coastal waters do not show permanent symptoms of eutrophication.
However, some estuaries and lagoons situated along the coast of
Portugal (Fig. 11.1) have very complex topographies, presenting interior
zones and enclosed arms, which show seasonal signs of eutrophication,
such as poor conditions of oxygenation, increasing nutrient levels and
development of large amounts of micro algae. In these areas, localized
proliferation of some macroalgae, mainly Ulva and Enteromorpha spp.
has been observed.
In general, they do not constitute a nuisance, except occasionally in
some aquaculture units and when close to beaches.
The vascular vegetation of salt-marshes is also disturbed, probably as
a result of human activities like waste discharges and dredging, as
indicated by changes in the distribution and abundance of the communities of Zostera and Spartina spp. and Chenopodiaceae.
Another indication for eutrophication or pollution in some localized
areas may be the occurrence of red tides along the Portuguese coast
during the past years.
Portuguese Institute of Marine Research, A V. Brasilia, 1400 Lisboa, Portugal
Ecological Studies, Vol. 123
Schramm/Nienhuis (eds) Marine Benthic Vegetation
© Springer-Vedag Berlin Heidelberg 1996