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The impact of Climatic Changes on the Adaptation of Marine Fish in the Baltic Sea

The impact of Climatic Changes on the Adaptation of Marine Fish in the Baltic Sea. Evald Ojaveer Estonian Marine Institute of the University of Tartu Margers Kalejs Georga Apina 22-8, Valmiera 4201, Latvia. Structure. Freshened Baltic water Halocline Modified saline water

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The impact of Climatic Changes on the Adaptation of Marine Fish in the Baltic Sea

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  1. The impact of Climatic Changes on the Adaptation of Marine Fish in the Baltic Sea Evald Ojaveer Estonian Marine Institute of the University of Tartu Margers Kalejs Georga Apina 22-8, Valmiera 4201, Latvia

  2. Structure • Freshened Baltic water • Halocline • Modified saline water A chain of basins separated by • topographic (coasts, islands, bottom relief), • or hydrological (fronts) constraints • SW and shallower parts -- boreal character • NW and deeper parts -- arctic

  3. Climate water masses inflowsSW Atlantic saline frequent E Continental Typical Baltic strong,moderate NW Atlantic/arctic Freshened only very strong

  4. Main environmental conditionsArea Salinity Ice (%) Temperature Spr.bloomKattegat 12-30/32-34 20 17/2 II-IIIBelts,Sound 8-17/16-23 30 17/2 IIIArkona 7.5-10/10-23 5 17/2 III-IVBornholm 7-8.5/14-21 0 17/2 IV Gotland 8/11-14 10 16.5/2 IV-V NW 7/9-12 40 16.5/1 IV-V GofRiga 5-7 100 18-19/0 IV-V GofFinland4.5-7/6-10 100 16/0-0.5 IV-V Bothn. Sea 6-7 100 14-19/0 IV-V Bothn. Bay 3-4.5 100 13-17/0 VI

  5. SW E NW GoF GoR GOB Spr. herring + + + + + + Sandeel + + + + + + Stickleback + + + + + + Flounder + + + + + (+) Sprat + + + + (+) Cod + (+) (+) Rockling + (+) Plaice + (+)? Dab +

  6. Adaptations • Higher fecundity • Earlier maturation • Lower specific gravity of eggs • Longer spawning period • Survival of deviated individuals

  7. Hydrographic conditions/year-class abundance

  8. Influence of higher salinity and mild winters Increase in population abundance Extension of the area

  9. Influence of stagnation,decrease of salinity in deeps, negative temperature anomaly in winter • Weakening of immigration • Strong natural selection for elimination of less adapted phenotypes

  10. Anthropogenic impacts • Increase of production in pelagic layers • Oxygen depletion in deep layers • Exploitation, especially overexploitation decreases abundance, possibly also genetic variation • Introduction of alien species has controversial influence

  11. Species of marine origin adapted in all regions of the Baltic Sea • Clupea harengus membras -- 10-12 major populations • Ammodytes tobianus -- probable several populations • Pomatoschistus minutus • Zoarces viviparus -- probably several populations • Triglopsis quadricornis -- probably several populations • Myoxocephalus scorpius

  12. Species adapted in the Baltic Proper • Platichthys flesus trachurus -- probably 6-7 local populations • Gadus morhua callarias -- 2 populations • Rhinonemus cimbrius • Sprattus sprattus balticus • Autumn spawning herring --several subpopulations

  13. Species adapted in the SW part of the sea • Pleuronectes platessa • Limanda limanda -- probably 2 populations

  14. Possible next important natural immigrant • Mackerel Scomber scombrus

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