la matière organique en mer méditerranée · •largest semi-enclosed basin of the earth •...
TRANSCRIPT
La Matière Organique en Mer Méditerranée
Richard Sempéré (MIO)
In relation with: MERMEX group: X. Durrieu de Madron, C. Guieu, I. Pairaud, P. Testor, C. Rabouille, O. Radakovitch, F. Carlotti, F. Van Wambeke, P. Conan, C. Estournel, F. D’Ortenzio, K. Desboeufs, M.
Mallet, E. Pullido-Villena, JO Irisson, C. Santinelli…
• Largest semi-enclosed basin of the Earth • Surface area: 2.5 x 106 km2 • Coastline: 46 x 103 km
• 0.7% surface; 0.25% of volume • Surrounded by three continents
Mean features of Med Sea
• Formed 150 millions years ago • During the Messinian salinity crisis (5.6 millions yrs ago) becomes
dessicated • 5.33 millions yrs ago, Atlantic waters rapidly refilled the basin
0 25 50 75 100 m
UV-A Penetration Depth (Sept 2001)
UV-A Penetration Depth (March 2001)
Med Sea main features!• Averaged depth : 1500 m (deepest point:
5267 m Ionian sea)
• Two undersea volcano • Two deep hypersaline anoxic basins
Eastern Med. Sea
• Deep water temperature > 12°C
• Evaporation exceeds Precipitation+Runoff, that is compensated by an inflow of Atlantic water of 0.5-1 106m3/s at Gibraltar
• High annual average total solar radiation flux = 168 Wm2 due to weak cloud cover
• Phytoplanktons dominate the visible light attenuation in Pacific, whereas in the Med. Sea, additional substances compete with algae for visible photons (CDOM, dusts?)
DESERT DUST
FOREST FIRES
POLLUTION
(Sea
WiF
S im
age,
© N
ASA
& O
rbim
age)
Med. marine air is mostly “continental” ! A natural laboratory, close from us, to study
(i) the ageing of continental air masses during long-range transport, (ii) the impact of aerosol on the regional climate, (iii) the impact of atmos. deposition on low-Chl, low-nutrient surface waters
BIOGENIC EMISSIONS
http://charmex.lsce.ipsl.fr
DESERT DUST The Mediterranean from space on a given summer day
Courtesy F. Dulac
Occurrence'of'extreme'atmospheric'events'in'the'Med'Sea'
Biomass!burning!
ex.$in$Greece$in$August$2007:$several$weeks$of$emissions$and$inputs$to$the$surface$waters$
Saharan!Dust!event!
ex. event in western Med.: dust input to the surface waters may reach 50 tons of dust km-2 within 2 days
2!examples!
These events may decrease marine primary production (PP) by decreasing available radiation or increase PP by injecting nutrients like phosphorus Saharan events : How those high inputs of new phosphorus will impact New Production, in particular from diazotrophs ? Other extreme events : River flood, Storms, Heat waves
July.$16>2003$
EMDW
WMDW
AW (0-100 m) S~36.0
AdDW
AW (0-100 m) S~38.0-38.6
NAdDW
CDW TDW
LIW (200-500 m) S~39.0-39.1
LIW (200-500 m) S~38.4
AW (0-100 m) S~37.0
Mistral Bora
General!oceanic!circula9on!features!
!
Courtesy, C. Santinelli (2014)
Physical and biogeochemical features
• Nutrient stœchiometry is not constant over the bassin (East–West gradient and surface-deep waters gradients
• Strong dynamic (general circulation + dense water formation + mixing) in specific area ! determine the distribution of nutrients at large scale
Bosc et al., 2004
• Strong trophic gradients; very poor waters in the Eastern Bassin; strong seasonal variability
N/P!=!25!
N/P!=!20!
Les objectifs scientifiques SeaWiFS satellite surface chlorophyll concentration observations (10 years) showed that Med. Sea is characterized by different trophic regimes
Coastal: high biomass in winter and a more reduced biomass in spring.
bloom in late winter-early spring months
�Intermittently blooming� zones with erratic regimes alterning intense biomass accumulation and oligotrophic conditions
Oligotrophic regions: higher and quite constant biomasses in fall-winter and lower and uniform values in late spring-summer
D’Ortenzio and Ribera d’Alcalà (2009)
NWestern
Winter mixing Unit and sinking POC: gC m-2yr-1
(Carlson et al., 2001; Avril et al., 2002; Moutin and Raimbault, 2002; Boldrin et al., 2002; Turchetto et al., 2012; Santinelli, 2014)
DOC/POC input due to winter mixing and dense water formation
1000 m
surface
Mesopelagic waters: Mineralization rate: 1.8-13.2 µMCyr-1
Tyrrhenian Sea Adriatic Sea
DOC: 10.9
Winter mixing
DOC: 3.2 DOC: 15.4
Sink. POC: 16.9 POC: 3.6-4.8 POC: 2.4
Dense water formation
WMDW: 0.14-1.2 Sv DOC: 9.5 x 1012 gC yr-1
NAdDW: 0.07 Sv DOC: 1.0 x 1012 gC yr-1
LIW: 1.0-1.5 Sv DOC: 10 x 1012gC yr-1
Levantine Int. water
East West
Unit: 1012gC yr-1
(Copin Montegut, 1993; Polat and Tugrul, 1996; Sempere et al., 2000; 2002, 2003; Dafner et al., 2001; Panagiotopoulos et al., 2013; Pulido Villena et al., 2008; De Vicente et al., 2012; Santinelli, 2014)
DOC : River Runoff, Atmospheric input, Straits
DOC stock in Med Sea ≈ 1980 x 1012 gC Primary production ≈ 276 x 1012gC yr-1
Atmospheric DOC: 5-9 Rivers DOC = 0.64-0.71
Prosope cruise-Autumn
Santinelli, Sempéré et al. (2013)
DOC and BP-Autumn W-E transect
DOC
BP
DOC and bacterial production (BP)-Autumn W-E transect
REGIONALISATION: Bio- and eco-regionalization of the Mediterranean Sea from data analysis in international databases
+ data collected by MERMEX
Spatial distribution of the Mediterranean marine ecosystems of the MS. Each ecoregion detected here represents a characteristic species association from primary producers to top predators forced by similar environmental conditions
Reygondeau et al. (2014)
Med Sea = 0.7% of global Ocean volume, but a major reservoir of diversity (18%) that might be affected by introduction of many thermophilic species and global change
=> disturbance of ecological status, changes in the trophic chain and consequently on the resources
Links with Biodivmex!
December 5th 2012 Med. Sea Biodiversity
groundwaters megacities
Rivers, groudwaters
Hydrodynamics and ecological processes
Land-Sea interactions and extreme events
air-sea interactions
Main driving forces in
Mediterranean Sea
Natural forcing in Med Sea
• Global Warming-Acidification • Pollutant effects
Projections for Med Sea
• Impact on oceanic circulation, on biogeochemical cycles on community structures
Tourism: 158 millions in 1996 (1/4 of world� tourism!!) => 300 millions in 2025
Ci9zens:!
$450$millions$in$2000$$$>>$550$millions$$in$2025$
==> Pollution : metals, oil (1 million tons/year - i.e. 20% of the global oil pollution in the world� oceans), drugs, hormones, several organic compounds and plastics. ==> Impact on exploited Resources ?
$$
High!concentra9on!of!people!in!coastal!area!
The'modern'anthropogenic'pressure'in'the'Mediterranean'basin'
PCB DD
T
Bio-Accumulat ion
PAH
BPA
PCB
DDT
Procaryote PAE
Plankton
High Trop. levels
Zooplank.
fish
Excretion, cycling
Bio-Accumulat ion
Assimilation
• Pollutants impact on C cycle. Ex. POPs associated to microplastics (MP). LABEX OT-Med, JPI Ocean (submitted)
Impact on biogeochemical cycles ?
Spatial distributions – and loads Costeau 7 April 2011
St1$St2$St3$
St5$
St6$ St7$St4$St8$St9$
St10$Zooplancton!
200>1000$μm$1000$–$2000$μm$
60>200μm$Phytoplancton!
0
5#000
10#000
15#000
ST1 ST2 ST3 ST9 ST4 ST7 ST5
CB#153
0
100
200
300
400
500
ST1 ST2 ST3 ST9 ST4 ST7 ST5
BDE.47BDE.47
0
5#000
10#000
15#000
ST1 ST2 ST3 ST9 ST4 ST7 ST5
p,p'#DDE
Marseille$
East West
ng.kg>1$dw.$
Rhône$
PBDEs Urban&inputs&&
OCPs Riverine fluxes &
PCBs East - West&
" Spatial and temporal (poster Tiano et al.) variation in plankton contamination
" Contaminants in all plankton size classes
" Rapid uptake of contaminants by plankton
" Trophic transfer in plankton not always seen
MERMEX 2015 Workshop
Tiano!et!al.!2014;!Tronczyński!et!al.!unpublished!
# Thermohaline$ circulaKon$ is$ driven$ by$difference$ of$ density$ between$ AtlanKc$ Ocean$and$Med.$Sea.$$
# Different$areas$of$dense$water$ formaKon$that$play$a$role$on$the$general$circulaKon,$transfer$of$carbon$ to$ deeper$ layers$ and$ availability$ of$nutrients$for$marine$organisms$and$ressources.$$
There!is!a!!"Conveyor!Belt"!system!similar!to!those!of!global!Ocean!
Global!warming:!Changes!of!Med!Sea!hydrodynamic!
!
Dense!water!forma9on!
ATMOSPHERIC,INPUTS,,
PYROGENIC
ATMOSPHERIC,INPUTS,,SAHARAN
WINDS
RIVERS
STRAITS
Anthropogenic forcing in Med. Sea
Strong!anthropogenic!pressure!
with!geographical!and!seasonal!
imbalances!
Surface!waters!:$+$1.1°C$$$$in$27$years$$
Deep!waters!:$+$0.05°C$$in$10$years$
A!changing!environment!:!
!onYgoing!increase!of!temperature!
Annual$mean$temperatures$in$the$Mediterranean$area$are$likely$to$increase$more$than$the$global$mean$(IPCC,$2007)$
1995$ 2005$Deep$water$at$DYFAMED$(Marty$&$Chiaverini,$2002)$
A!unique!coupled!system!(ocean/
atmosphere/con9nent)!
Possible change that may affect winter convection in open Mediterranean Sea ! By using IPCC-A2-scenario (Surface T (+3.1°C ) and S (+ 0.48 psu)) Somot et al. (2006) indicated
Somot$et$al.Clim.$Dyn.$(2006)$
Possibility$ of$ decrease$ of$ surface$ density$ and$winter$ deep>water$ formaKon$ at$ the$end$ of$ the$ 21st$ century,$ the! Mediterranean! thermohaline! circula9on! (MTHC)!
weakening! can!be!evaluated!as! −40%! for! the! intermediate!waters!and!−80%! for!
the!deep!circula9on!with!respect!to!presentYclimate!condi9ons!
Change!in!organic!ma_er!export!in!the!mesopelagic!waters!of!the!Med!Sea?!
Decrease!of!nutrient!uplia!,!Oxygen!transfer!and!Ressources!?!
Warming!!Changes!in!water!masses!circula9on!
Sensors (T, S, NO3, Chla et CDOM, O2, BB, PAR)
Dense water formation (DEWEX results, WP1 MERMEX)
1km ~2-5km
Data Centers
Land Station
Scientific/ operational community,
users
Profiling floats
Gliders
Most data available in real time (T, S, Chla, O2) at Coriolis/Sedoo
Dewex experiment: Gliders, Profiling floats, Drifters, Cruises, Moorings (WP1 MERMEX, DEWEX)…
01/07/2012 -> 07/10/2013 30 Glider deployments ~ 13,000 profiles (0-1000m) 6 CTD cruises ~ 400 profiles (0-bottom) 27 Argo ~ 1,500 profiles (0-1000m or 0-2000m) 10 Marisondes and surface drifters
Pot. Temp Salinity Pot. Dens. Oxygen Fluo Chla Turbidity north south Northern Current
North Balearic Front
Mixed patch
Gliders: • Reveal a wide range of variability (small!basin scales) • Are present at sea even during strong weather conditions • Allow to study the physical-biogeochemical coupling
A vertical section from a glider:
eddies Plumes ~1km
Multidisciplinary data: (WP1 MERMEX, DEWEX)
Chlorophyll Gliders transects
(WP1 MERMEX, DEWEX)
Sunmex (MERMEX WP4), Marseille Bay UV and PAR radiations effects on marine ecosystems
In relation with mixed layer
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0
0.1
7/11/719/12/7
5/2/814/2/8
26/3/829/4/8
5/5/823/6/8
10/7/8
Atmosphere
2 m depth water column
23/9/814/10/8
25/11/87/12/8
UV
R-B
/UV
R-A
*10
• These UVR values are the first ever reported on an annual basis in Mediterranean Sea.
• Examination of the ratios of UVR-B/UVR-A shows that UVR-B increased 7 to 8 fold more than its UVR-A during the summer.
UVR-B/UVR-A x 10
Radiative fluxes
H(0-,λ)
H(5,λ)
H(10,λ)
H(m,λ)
0 1 2 3 4 5 6
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35
H(0-,λ)
H(5,λ)
H(10,λ)
H(m,λ)
0.0 0.2 0.4 0.6 0.8 1.0 1.2
0.000 0.002 0.004 0.006 0.008 0.010 0.012 0.014
Dose at 380 nm (kJ m-2)
Dose at 305 nm (kJ m-2)
June 08
December 08
aCDOM(350) = 0.123 m-1
Kd(305) = 0.48 Kd(380) = 0.17
Zm = 6 m
aCDOM(350) = 0.112 m-1
Kd(305) = 0.28 Kd(380) = 0.14
Zm = 50 m
The wavelength 305 nm is used as biologically effective wavelength for the induction of DNA damages (CPDs), while 380 nm is used as biologically effective wavelength for the induction of photorepairs (PERs).
UV-B (305 nm) and UV-A (380 nm) doses (H(Zm,λ) in kJ m-2)
received beneath surface [H(0-,λ)], 5 and 10 m [H(5,λ) H(10,λ)] and mean doses received within the mixed layer [H(m,λ)]
0
10
20
30
40
50
60
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Q
Zm
Q =
H(m
,305
)/H(m
,380
)(%
)
Date
Z m(m
)
Ratio (Q) of the mean doses received within the mixed layer at 305 (UV-B) and 380 nm (UV-A) along with mixed layer depth (Zm in m) at solar noon at the SOLEMIO station: SUNMEX
Q in % = H(m,305)]/H(m,380) x 100]. mixed layer depth (Zm in m).
Sarmiento$et$al.$1998,$Bopp$et$al.$2001,$Doney$et$al.$2006$
Mechanisms:$increased$ocean$straKficaKon$!$reduced$nutrient$supply$/$light$limitaKon$
MulKple$Stressors:$changes$in$NPP$
Increase of photochemical oxidation reactions
singlet$oxygen$transfer$to$associated$bacteria$
adached$bacteria$
1O2!
growth$limitaKon$
death$and/or$repulsive$effect$
minor$bacterial$degradaKon$of$phytoplankton$components$
LimitaKon$of$bacterial$growth$
Minor$biodegradaKon$of$phytoplankton$components$$
Solar$radiaKon$induce$Transfer$of$singlet$oxygen$from$dead$phytoplanktonic$cells$to$adached$bacteria$$
$senescent$phytoplankton$cells$hν
Rontani et al. (2013); Petit (PhD) et al. (2013, 2014)
Metabolic and structural changes of the bacterial community in response to the phototransformations of dissolved and particulate organic matter in the Mediterranean Sea
PHOTOMED
Radiative fluxes
Thank you
MERMEX group: X. Durrieu de Madron, C. Guieu, I. Pairaud, P. Testor, C. Rabouille, O. Radakovitch, F. Carlotti, F. Van Wambeke, P.
Conan, C. Estournel, F. D’Ortenzio, K. Desboeufs, M. Mallet, E. Pullido-Villena, JO Irisson, C. Santinelli…