The Chilean coast
Ahumada, R.B.; Pinto, L.A.; Camus, P.A. (2000). The Chilean coast, in: Sheppard, C.R.C. (Ed.) Seas at the millennium: an environmental evaluation: 1. Regional chapters: Europe, The Americas and West Africa. pp. 699-717 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 |
| Available in | Authors | | Document type: Review
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| Authors | | Top | - Ahumada, R.B.
- Pinto, L.A.
- Camus, P.A.
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| Abstract | The Chilean coast extends from 18°30" to 57°30"S, along the western coast of South America. This region of the Pacific is under the influence of a sub-Antarctic current system, known as the Humboldt Current. Dominant coastal south-southwest winds cause seasonal upwelling near the coast. Upwelled water masses rich in nutrients are responsible for an elevated primary production in coastal waters which can sustain an annual fisheries of seven million tons. The Chilean coast is a straight, west-facing shoreline with few embayments. A desert dominates the north part of the country, a transitional region is in the centre and temperate forest develops in the south. In the north, industrial development has occurred including mining, exploitation of marine resources and the installation of fuel terminals. Dumping and disposal of mining tailings on the coast of Chañaral is considered one of the major environmental impacts of mining activities in the country. Agriculture, manufacturing and heavy industry appears in the central part of Chile. Between 34° and 42°S, timber, pulp and cellulose industries together with dairy farms are important. Recent development in coastal areas has expanded the oil and fishmeal industries, the chemical industry, oil refineries, the loading of mineral ores, and general loading of goods -all exerting pressure on the few semi-enclosed embayments. The impact of these activities is local but very intensive, causing the disappearance of local fauna. The morphology of the southern coast beyond 42°S is complex and formed by fjords, channels and islands. Recently, this region has increased its economic development mainly by the creation of salmon farms, exploitation of timber, and tourism. This area has a low-density population, but this could change drastically in the new millennium. Mining of zinc and lead along the Aysen Sound are potential sources of contamination in what can still be perceived as a pristine area. The effects of "El Niño" events -the regional manifestation of a large-scale ocean-atmosphere fluctuation (Southern Oscillation)- on the Peruvian and Chilean coasts are varied and dependent on their intensity , and are often perceived as 'positive' or 'negative' according to their impact on human populations or economic activities. These effects can also be classified as biological or physical ones, which are usually interdependent. To date, the real ecological or evolutionary impact of El Niño on coastal species or communities remains largely unknown. Environmental conditions on the coast of Chile are strongly influenced by the nature of the water masses. The subantarctic water mass (SAAW) regulates the coastal climate while the subsurface equatorial water mass (ESSW) brings nutrients and low oxygen to the surface waters during upwelling events. Introduction of high-nutrient, low-oxygen waters to shallow embayments causes high primary production to increase, high sedimentation rates generating sub-oxic bottom waters. These ecosystems are highly susceptible to contamination by high loads of organic matter, creating eutrophic or even hypertrophic conditions. Saltmarshes are an example of subsystems where hypertrophication has occurred as a result of pollution (Rudolph and Ahumada,1987; Ahumada et al.,1989). The large-scale patterns of distribution and abundance of marine species in Chile has four major determinants. The first is a massive cooling effect along the continental coast associated with the combined influence of subantarctic waters and upwelling processes, which confer a predominantly cold character on the biota. The second is the latitudinal variation of climatic and topographic features of the coast, which is important in the differentiation of the present main biogeographic regions. The third is a possible spatial differentiation of the biological consequences of El Niño (and La Niña) on coastal populations and communities, in which the northern Chilean area would have experienced greater disturbance effects at historical time scales. The fourth is a factor of a different nature such as the geographical variation in the occurrence and strength of anthropogenic impacts due to the marked spatial differences in the distribution and concentration of both coastal human populations and industrial activities along the coast. The creation of the National Environmental Commission and recent environmental regulations have recently begun to help public awareness about environmental issues. Consultants have gained experience in understanding the need to harmonize economic development with nature conservation. Slowly, these new ideas are helping in the preservation of the coastal environments in Chile. |
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