Abiotic conditions in the marine environment

1. Abiotic conditions in the marine environment Salinity Light Temperature Pressure Dissolved Oxygen (DO)

2. Unicellular adaptations to low DO • Mostly metabolic adaptations • anaerobic respiration • use reduced organic compounds in sediments as energy sources • use alternatives to O2 as e- acceptors • facultative vs. obligate anaerobes

3. Multicellular adaptations to abiotic conditions - in plants • plants sensitive to flooding will shut down aerobic metabolism & other processes, leading to organelle and cell death • stresses to wetland plants: • anoxia around roots • toxic levels of reduced minerals (Fe, Mn, S) around roots

4. Multicellular adaptations to abiotic conditions - in plants • halophytes: plants tolerant to flooding • structural adaptations • aerenchyma • adventitious roots, prop roots, lenticels, pneumatophores • pressurized gas flow • physiological adaptations • anaerobic respiration in roots

5. Spartina anglica root corn (Zea mays) Aerenchyma

6. Screw pine Red mangrove, Rhizophora mangle Adventitious roots: roots arising from stems Prop roots & lenticels

7. bald cyprus, Taxodium distichum black mangrove, Avicennia germinans Adventitious roots: roots arising from stems pneumatophores

8. on black mangrove and Frankenia on a Distichlis blade Vascular plant adaptations to wetlands salt glands • roots & leaves may also filter out salts, preventing them from entering cells

9. Animal adaptations to wetlands coping with anoxia • invertebrates cope with anoxia better than vertebrates • many use anaerobic respiration, especially glycolysis • structural & behavioral modifications for O2 uptake: • respiratory organs • move to normoxic areas • ventilation • distribute O2 through body (circulatory systems, hearts, vascularization) • respiratory pigments • physiological adaptations • behaviorally: e.g. reduce activity, close shell

10. Animal adaptations to wetlands coping with salt • Explain how each type of organism responds to changes in the salt concentration of the environment • How might each organism accomplish this? • What do you think is better to be: an osmoregulator, or an osmoconformer? Why?