Data/hora: 10/06/2024 10:18:01

Provedor de dados: | 5
País: | France
Título: | Les consequences de l'echouement de l'Amoco Cadiz" sur les peuplements algaux exploitables
Autores: | Kaas, Raymond.
Data: | 1980-06
Ano: | 1980
Palavras-chave: | Seaweeds; Pollution Effects; Marine Pollution; Oil Spill.
Resumo: | Introduction. The amount of hydrocarbons dumped into the sea is currently estimated at 6 to 16 million tons per year. This pollution comes from various sources: Chronic discharges associated with human activity such as oil tanker deballasting or discharges from coastal petroleum processing facilities; natural chronic discharges; accidental discharges like leaks coming from drilling well heads or oil tanker accidents. Natural spills happen, in general, in a relatively unobtrusive way and their effects are quickly diminished by significant dilution and rapid degradation of the various components. Oil spills, however, are characterised by a massive and occasional supply of hydrocarbons. The "Amoco Cadiz" shipwreck fits in with this last case and has seemed all the more disturbing because it occurred in the midst of a region that, considering its fauna, flora and economy, is one the French coastline's richest. It supplies, in fact, more than three fourths of the French harvest of carrageen, which is the essential raw material for factories producing alginates, and 70% of the harvest of red algae of the species Chondrus crispus from which the industry extracts carrageen. The future of the occupation of seaweed harvester and the industries that depend on it are linked to the impact that the Amoco Cadiz oil spill might have on plant populations. It was agreed that the harvest would continue as long as there were no conspicuous symptoms detected indicating a change in the algal populations or the appearance of significant difficulties as far as repopulation was concerned. That is why we have endeavoured to monitor on a permanent basis the changes in fields of algae that are of direct interest for farming, that is to say, the fields of Laminaria digitata and Chondrus crispus. Because this catastrophe was the biggest that had occurred up to that time, it was difficult to foresee what would happen in the short, mid and long term at the level of the algae's metabolism, their ability to reproduce and the value of the finished products. Although we only have scant knowledge of the effects of hydrocarbons on algal flora, a certain number of factors are already known. O'Brien and Dixon (1976) note that the better part of marine vegetation located at rather low levels escape, for the most part, significant harm caused by hydrocarbons. Most authors are in agreement in saying that the most pronounced toxic effects are related to the direct contact of algae and oil. The organism's response is eminently variable and is a function of many factors such as the quantity and quality of the petroleum, the time of contact as well as its aptitude for dissipating. The physiological state of the plant, its vulnerability vis-à-vis other chemical substances and temperature also come into play. The study of the physiological repercussions shows a decrease in photosynthetic activity (North, Neushul and Clendenning, 1965) and an inhibition of the synthesis of DNA and RNA has been brought to light by Davarin (1975). Boney (1974) notes a reduction in the rate of growth and the induction of tumorous growths by carcinogenic polymorphonucleocyte aromatics. Significant accumulations of polluting hydrocarbons were found in Fucus gardneri (Clark et al, 1973) and the ulva populations of the San Francisco Bay show content levels that are eight times higher than those of non-polluted areas (Disalvo, 1975). In general, organisms at upper levels suffer more significant damage than those at the lower levels (Smith, 1968). The disappearance of herbivorous molluscs (Chasse, 1978) can cause species normally set at lower levels to rise (Southward and Southward, 1978). The seriousness of the damage varies according to factors associated with the specific pollution, such as detergents, for example. After the "Torrey Canyon", the Fucus spiralis populations were more affected than the other Fucacae, a large share of the damage being due, moreover, to detergents (Smith, 1968). The Irini accident in Sweden released significant amounts of heavy hydrocarbons and Notini (1978) observes no significant damage for marine macrophytes. At the time of the Santa Barbara oil spill, Holmes (1969) makes the same observations. Some plants, like red algae, seem to be the most affected (Boney, 1974). Two years after the "General M.C. Meigs" shipwreck, in the state of Washington (1972), the Laminaria Anderson populations had not yet returned to their normal state.
Tipo: | Text
Idioma: | Francês
Identificador: | http://archimer.ifremer.fr/doc/1980/publication-1950.pdf
Editor: | ISTPM
Relação: | http://archimer.ifremer.fr/doc/00000/1950/
Formato: | application/pdf
Fonte: | Revue des Travaux de l'Institut des Pêches Maritimes (0035-2276) (ISTPM), 1980-06 , Vol. 44 , N. 2 , P. 157-194
Fonte: | Ifremer