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The north coast of Spain
Díez, I.; Secilla, A.; Santolaria, A.; Gorostiaga, J.M. (2000). The north coast of Spain, in: Sheppard, C.R.C. (Ed.) Seas at the millennium: an environmental evaluation: 1. Regional chapters: Europe, The Americas and West Africa. pp. 135-150
In: Sheppard, C.R.C. (Ed.) (2000). Seas at the millennium: an environmental evaluation: 1. Regional chapters: Europe, The Americas and West Africa. Pergamon: Amsterdam. ISBN 0-08-043207-7. XXI, 934 pp., more

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  • Díez, I.
  • Secilla, A.
  • Santolaria, A.
  • Gorostiaga, J.M.

Abstract
    The North coast of Spain is an open coast characterised by a narrow continental shelf where weak, variable and wind driven currents prevail. The annual phytoplankton and zooplankton cycle follows the pattern of a temperate sea with the highest planktonic biomass in spring followed by a secondary peak in autumn. During summer water stratification, this typical cycle can be modified by the development of shelf-edge fronts and coastal upwellings. Other important physical processes and hydrological structures of the area are the warming trend of the sea surface temperature (SST) (a mean increase of 1.4°C for the period 1972-1993), the poleward geostrophical warm current running northwards along the Portuguese-Spanish slope during winter, the development of slope water oceanic eddies, and annual warming of waters off the eastern coast as a result of the entrainment of water masses during the spring-summer period. Thus, SST in the Basque coast ranges from 11°C to 22°C, in winter and summer, respectively, whilst in Galicia it varies from 13.5°C to 19°C, respectively. This leads to a geographically varied flora and fauna, in which the Galician coast is enriched in septentrional species, whilst the Basque coast shows a remarkable resemblance to the Portugal and northern Atlantic Morocco communities. The great pressure of uses on the coastal fringe and the lack of enforcement of strict limits to human interventions have led to the environmental degradation of some parts. Estuaries have been specially impacted as a result of the concentration of industrial-urban centres in these areas since the end of the 19th century. Pollution and land reclamation process of estuarine intertidal areas and coastal wetlands have led these areas to be among the most threatened habitats in the north coast of Spain today. Despite protective measures, the landfill continues, mainly related to tourism. Urban centres have serious infrastructural deficits in waste-water treatment systems, such that only 20% of the total 12 million population equivalent conforms with the requirements of Directive 91/271/EC concerning urban waste-water treatment. Nutrient enrichment from agriculture does not seem to have affected the general pattern of nutrient limitation during summer water stratification, but there is no information on pesticide impacts in coastal waters. On the other hand, environmental eutrophication resulting from aquaculture on the western coast (Rias Bajas) has been related to the appearance of toxic marine phytoplankton blooms. Mining, steel industries and metal treatments have been predominant industrial activities for decades, as is revealed by extremely high heavy metal concentrations in several coastal areas. The eastern part of the coast has been the most impacted region. Gross organic enrichment, water oxygen depletion, anaerobic sediment conditions, high heavy-metal concentration and trace organic pollutants (PARs, PCBs, and pesticides) have led to extremely reduced fauna along the Nervión estuary (Bilbao). With respect to navigation and routine port operations, a comprehensive impact assessment has not been carried out. However, the use of tributyltin (TBT) in antifouling paints for fishing and merchant fleets has been reported to have harmful effects on benthic communities. The northwestern coast of Spain is particularly exposed to oil spills. The most notable recent accidents have been the wrecks of 'Aegean Sea' (in 1992) and 'Monte Urquiola' (in 1976), with 79,096 and 100,000 tonnes of oil released into the sea, respectively. Other environmental concerns arise from the over-exploitation of living marine resources. Hake, anglerfish, megrim and blue whiting, and the pelagic sardine, anchovy , mackerel, horse mackerel and albacore are the main species exploited in the area by coastal fisheries. Most of them are fully or over-exploited and discards represent a high percentage of the catches. In addition, fisheries have a major impact on shelf communities due to the degradation of sea bottom habitats by trawling. The increase of economic, human and legal efforts for the protection of natural resources carried out over the last few years is insufficient. In order to efficiently protect those still extensive well preserved shores and to recover the degraded ones, Spanish Authorities need to enforce strict limits. Likewise, they should formally establish an appropriate and global strategy to progressively reduce industrial and domestic waste-waters with the long-term goal of zero discharge. Finally, more environmental surveys should be carried out in order to manage properly the coastal habitats and to assess reliably their conservation state.

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