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Assessment of the main drivers of the Black Sea ecosystem functioning Mnemiopsis leidyi and Beroe ovata impact on the Black Sea ecosystem. Modeling approach.

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Presentation on theme: "Assessment of the main drivers of the Black Sea ecosystem functioning Mnemiopsis leidyi and Beroe ovata impact on the Black Sea ecosystem. Modeling approach."— Presentation transcript:

1 Assessment of the main drivers of the Black Sea ecosystem functioning Mnemiopsis leidyi and Beroe ovata impact on the Black Sea ecosystem. Modeling approach. Tamara Shiganova P.P.Shirshov Institute of oceanology RAS, Moscow, RUSSIIA Paul Nival Laboratoire d'Oceanographie de Villefranche Villefranche-sur-Mer, FRANCE

2 Distribution of M. leidyi in the native and invaded areas Costello J. H., J. E. Purcell, K. M. Bahya, H. W. Mianzan & T. A. Shiganova, 2011 Native area Invaded area

3 In the Black Sea, native gelatinous species belong to moderately cold-water species: the ctenophore Pleurobrachia pileus, scyphomedusa Aurelia aurita, and the pyrophyte alga Noctiluca scintillans. Two warm water invasive ctenophores arrived and established in the heated upper layer Cold water species Warm water species Subdivision of the gelatinous species in their relation to mean seasonal, annual and minimal winter SST: analyses of field data according to main component method )

4 Population genetic analyses supported its invasion from the Gulf of Mexico (e.g., Tampa Bay) into the Black Sea, then secondary into the Azov, northern Aegean and into the Caspian Sea and the Mediterranean (Ghaboolia, Shiganova et al., 2010) Dispersal of Mnemiopsis leidyi in the Eurasian seas Mnemiopsis leidyi

5 Dispersal of Beroe ovata in the Eurasian seas Beroe ovata

6 Black Sea Sea of Azov Aegean Sea Caspian Sea Baltic Sea The dark area Corresponds to the period of Mnemiopsis leidyi occurance (observations) Environmental data and M.leidyi invasion in the seas of Eurasia After Shiganova et al., in press

7 Interannual variation of M.leidyi and B.ovata in the Black Sea

8 Zooplankton are the main food of M.leidyi Change of interannual variability of edible zooplankton after appearance of invasive ctenophores in the inshore and offshore waters in August in the northeastern Black Sea

9 Mnemiopsis leidyi seasonal cycle in cold (1993) and warm (1994) year before B.ovata arrival Field data in the coastal area r=0,6-08, p<0,001 Cold year Warm year Before the arrival of B.ovata, M.leidyi abundance was controlled by temperature and zooplankton prey

10 Temperature Zooplankton M.leidyi B.ovata A J L E E A A J L

11 Interannual variability of phenology of ctenophores M. leidyi and B.ovata in the coastal area of the NE Black Sea Interannual variability of phenology of ctenophores M. leidyi and B.ovata in the coastal area of the NE Black Sea Time of appearance of B.ovata Time of beginning reproduction of B.ovata Time of appearance of M.leidyi Time of pick of reproduction of M.leidyi --- M.leidyi --- B.ovata

12 Life stages and forcing factors for M.leidyi and B.ovata L J E A food Temperature Individual based modeling approach was used to take into account life cycle and physiological features E – eggs L-larva J-juvenale A-adult - mortality

13 Forcing functions Zooplankton biomass Temperature

14 Mortality rate Food Temperature Mortality rate Model

15 Temperature food Prey – predator individual based model structure M.leidyi B.ovata

16 Age classes L A J nono nLnL nJnJ nAnA process ageing

17 Age classes L A J nono nLnL nJnJ nAnA process ageing 0% 50% 100%

18 Change in stage duration depending on physiology (food, temperature)

19 Time (days)Number individuals per unit of volume first larva first egg first adult first juvenile Model Ontogenetic cycle of M.leidyi and B.ovata development

20 Reproduction rate ExperimentsModel M.leidyi B.ovata

21 Ingestion rate coefficient (0 – 1) C2= (Food- minFood)/ (Kf+ (Food-minFood)) C2 = 0 when Food < minFood Food minFood experimentModel Ingestion rate

22 Stage duration age to 50% transfer Temperature (°C) Ingestion Stage duration (days optimum conditions

23 First stage: M.leidyi present B.ovata absent A L J E

24 M.leidyi B.ovata A L A L Second stage B.ovata appears in surface water at time 200 th day Simulation of input of B.ovata in surface water at time 200th day. M.leidyi develops a bloom, which is grazed by B.ovata Predation on larvae, juveniles and adult on M.leidyi makes them disappear Model E JE J

25 M.leidyi B.ovata A L A L ModelField observations M.leidyi B.ovata L J A L E A J E

26 Conclusions In present Black Sea ecosystem there is a bottom up control from zooplankton to its consumer Mnemiopsis leidyi and finally to its predator Beroe ovata. Annual changes in temperature and food availability are considered as the main factors that control these predators dynamics and their impact on pelagic ecosystem of the Black Sea. Both field data analyses and individual based modeling confirmed that, with appearance B. ovata that controlled M. leidyi population, a recovering shift of the ecosystem appeared but was controlled by climate forcing. Now in any case it is another ecosystem with two ctenophores that affected ecosystem but the time of high effect of M.leidyi is much shorter.

27 Acknowledgement The research was performed in framework of project GK-0422

28 Thank you for attention


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