RESPONS OF MEDITERRANEAN ECOSYSTEM ON ANTHROPOGENIC DISTURBANCES. Global changes, impacts of river and atmospheric inputs

Transcription

1 RESPONS OF MEDITERRANEAN ECOSYSTEM ON ANTHROPOGENIC DISTURBANCES Global changes, impacts of river and atmospheric inputs

2 Mediterranean Sea = «small Ocean» Area for deep water formation Cyclonic circulation with many mesoscales features (frontal zone, eddies, coastal upwelling ) Oligotrophic system with a west to east gradient and specific N/P ratios Nitrate = µmoles/l Phosphate = µmoles/l Silicate = µmoles/l N/P = 20 Nitrate = 8.5 µmoles/l Phosphate = 0.40 µmoles/l Silicate = 8.4 µmoles/l Oligotrophy P deficiency N/P = 25 Nitrate = 4.5 µmoles/l Phosphate = 0.2 µmoles/l Silicate = 6 µmoles/l Image SEAWIFS aimablement fournie par la NASA et le GSFC Figure 1 : Image Satellitaire composite décrivant les concentrations de chlorophylle de surface en Méditerranée. Le The Rhône river: most important river in the western golfe du Lion soumis aux apports rhodaniens apparaît comme une région très productive. On remarque également la diminution des teneurs en chlorophylle entre le bassin occidental et le bassin oriental, due à un gradient marqué des concentrations des éléments nutritifs (nitrate, phosphate, silicate) des eaux profondes. Mediterranean

3 The western basin is strongly urbanized Sensors OLS of DMSP MARSEILLE GENES BARCELONE ROME NAPLES VALENCE PALERME ALGER TUNIS NOAA The Mediterranean sea provides a unique environment to observe changes at local and large scales

4 Some changes are already noticeable Surface temperature 1.1 C / 27 ans = 0.04 C / an Temperature and salinity at 2000m depth (Béthoux et al.,1992) Extraits de Salat et Pascual, CIESM Workshop Series #16 On «Tracking long-term hydrological change in the Mediterranean Sea»

5 Spectacular changes!!! Hydrological characteristics of water masses have changed in the strait of Gilbraltar (Fuda et al., 2005)

6 Near the coast: Bay off Marseille Drastic changes in ? Saltier waters SALINITY Lafont et al., 2004

7 Near the coast: Bay off Marseille Drastic changes in ? «Green» water CHLOROPHYLL Lafont et al., 2004

8 Timle evolution of nutrient in the Rhone River 2,5 2 Phosphate Nitrate 1,5 1 mg.l -1 0,5 Mediterranean Sea ANNEE The nitrate/phosphate ratio increases NID/PO4 N/P DYSTROPHY N/P > 50 N/P = janv.-00 juin-01 avr.-04 août-05 janv.-07 juin-08 nov.-09 avr.-11 sept.-12 févr.-14 juil.-15 août-16 mai-17 avr.-18 janv.-19 nov.-19 août-20 mai-21 janv.-22 oct.-22 juin-23 mars Jours

9 Evolution of chemical composition: Phosphate? 0,44 0,42 P hosphate µ M 0,40 0,38 0,36 0,34 0,32 0,30 Increasing of 3 % per year (Béthoux et al.88;92) Béthoux et al., ANNEE Consequences : eutrophication - Anoxia

10 But taking into account the regional variability cancels this temporal evolution 0,44 0,42 0,40 Phosphate µ M 0,38 0,36 0,34 0,32 prof. > 1000m Béthoux et al.(1988, 1992) 0, ANNEE Need of adapted data to correctly detect long term evolution

11 Western Mediterranean Sea Threatened system The anthropic action could be desastrous along the coasts as well as off shore Despite intensive research efforts undertaken over more than a century, an integrated view of the evolution of Mediterraean Sea is still lacking The ocean is critically under-sampled both in space and time

12 Western Mediterranean Sea Historical data are useful but not enough sufficient to quantify temporal evolution Need for long-term observation near the coast and offshore based on multi-sites system To observe spatio-temporal variability COM has recently developped long term- time series associated with new french programms on the Mediterranean Sea (HYMEX, MERMEX, MOOSE)

13 MONITORING OF INPUTS FROM THE RHONE RIVER Automatic sampling at high frequency To take into account short and violent flash-floods

14 Recent results: Short-term evolution during flash-floods 6000 DEBIT RHONE 2,5 m3/s PHOSPHATE µm 2,0 1,5 1,0 0, avr-08 mai-08 mai-08 juin-08 juil-08 juil-08 0,0 avr-08 mai-08 mai-08 juin-08 juil-08 juil-08 DATE DATE Carbone Organique Particulaire µm avr-08 mai-08 mai-08 juin-08 juil-08 juil-08 DATE AZOTE µm avr-08 mai-08 mai-08 juin-08 juil-08 juil-08 DATE

15 Monitoring of meteorological data and atmospheric inputs (Most important source of pollution in the open sea) Collecteur de retombées atmosphériques Rayonnement UV (LMGEM) And numerous observations at sea between the Rhone mouth and the bay off Marseille

16 Inputs from Rhône river Atmospgeric inputs Meteo Marseille Long-term mooring Continuous meaurements during transit Hydrology OBSERVATION SITES NEAR MARSEILLE Air Mer Turbidimètre NKE Unité de stockage données Radiomètres (Stor-X) 60 m maximum = Connexion radiomètres Radiomètre Satlantic + bioshutter Batterie radiomètre 4-6 m Radiomètre Satlantic + bioshutter FLOTTEUR LEST Long-term moorings

17 Elaborating a realistic monitoring strategy to describe long-term hydrological variations at large scale in the Mediterranean Sea CSIC COM OGS IEO CNR SHOMAR ISMAL HCMR INSTM AUDO/NIOF In operation Foreseen The CIESM observational network : HYDROCHANGES Service d Observation

18 Recent results 0.01 C/year

19 All these operations have been proposed for the elaboration of the new programme «Mediterranean Ocean Observation On Environment (MOOSE) Moorings v Stations littorales Stations côtières (plateau talus) Stations du large v v v v Gliders Radars transits with continuous measurements + Lagragian floats