the impact of climatic changes on the adaptation of marine fish in the baltic sea evald ojaveer...
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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
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
Climate water masses inflows
SW Atlantic saline frequent E Continental Typical Baltic strong,moderate NW Atlantic/arctic Freshened only very strong
Main environmental conditions
Area Salinity Ice (%) Temperature Spr.bloom
Kattegat 12-30/32-34 20 17/2 II-III
Belts,Sound 8-17/16-23 30 17/2 III
Arkona 7.5-10/10-23 5 17/2 III-IV
Bornholm 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
SW E NW GoF GoR GOB
Spr. herring + + + + + +
Sandeel + + + + + +
Stickleback + + + + + +
Flounder + + + + + (+)
Sprat + + + + (+)
Cod + (+) (+)
Rockling + (+)
Plaice + (+)?
Dab +
Adaptations
• Higher fecundity
• Earlier maturation
• Lower specific gravity of eggs
• Longer spawning period
• Survival of deviated individuals
Influence of higher salinity and mild winters
Increase in population abundance
Extension of the area
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
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
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
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
Species adapted in the SW part of the sea
• Pleuronectes platessa• Limanda limanda -- probably 2 populations