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Are the Meditterranean waters becoming warmer? Information from biological indicators

TitreAre the Meditterranean waters becoming warmer? Information from biological indicators
Type de publicationJournal Article
Année de publication1994
AuteursFrancour P, Harmelin-Vivi ML, Harmelin JG, Boudouresque CF, Quignard JP
JournalMarine Pollution Bulletin
Mots-clésbiological indicator, climate change, fauna, flora, France, Golfe du Lion, Ile de Port-Cros, littoral, long-term monitoring, Mediterranean sea, Méditerranée nord-occidentale, Méditerrannée occidentale, Mer Méditerranée, north-western Mediterranean, ocean, pollution, Port-Cros Island, Provence, réchauffement, Scandola, sea water temperature, shallow water, temperature, température de l'eau de mer, warming, western Mediterranean, wind

Important changes described in the marine littoral zones throughout the world are attributed to short term phenomena such as marine pollution. Recently, a few authors have emphasized medium to long-term modifications of the ocean conditions (Mearns, 1988). Increasing concentrations of carbon dioxide and other infrared absorbing gases are widely proposed as a mechanism of global surface warming over the next several decades (Ausubel, 1983). Over the past 20-30 years, a significant increase in the average temperature of the waters of the western Mediterranean basin has been observed: between 1973 and 1987, an increase of 0.4°C at 80 m depth (Pascual, pers. comm.), and between 1959 and 1989, an increase of 0.12°C under 400 m (Bethoux et al., 1990). Similar observations have been made in the other ocean basins (Bindoff & Church, 1992). In view of our present-day knowledge of the shallow waters of the Mediterranean, we can only put forward a model-based assumption of temperature increase (Bethoux et al., 1990). Winds, currents and albedo can strongly induce variations of the surface temperature (lvanoff, 1972) but physical measurements cannot demonstrate a significant mean temperature increase at present, even if it exists. However, the possibility of an increase is suggested by the marine flora and fauna which integrate medium-term changes in ambient conditions (Soule & Keppel, 1988). Unusual occurrences in marine life may also be used as indicators of changing ocean conditions (Mearns, 1988).

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