Water in the Ocean Water properties Organisms and water PressureTemperatureLightChemistryO2CO2CaCO3Salinity Life in the water

Water Water molecule: electric dipole Salinity: dissolved solids 35ppk: marine water Residence times of elements Amt (g)Resid t Na147 X X 10 8 K5.3 X X 10 7 Ca5.6 X X 10 6 Si5.2 X X 10 4 Mn1.4 X X 10 3 Fe1.4 X X 10 2 Al1.4 X X 10 2 Not cumulative Removal:SedimentsOrganisms Mineral precipitation Sea spray

Water Liquid is fluid. Fluid will change shape as force is applied Gas is also fluid, but fills space; liquid has surface Density  How tightly packed are molecules Pure H2O: 1.0 g/cm^3 Seawater: g/cm^3 T, salinity affects Water is unusual in  changes Viscosity Resistance to change in shape Important to microorganisms

Organism Sizes and Water Large size: control movement, food contact Self-propelled: Buoyancy, swimming Hunting, scavenging, grazing Small size: water has huge effect Viscosity Ltd propulsion: Migration, currents, settling Boundary layer: microorganisms, filter feeders

Pressure Vertical variability: 1 atm per 10 m Static variability: can change with tides Stenobaric, eurybaric May or may not effect benthos, but have to deal with it! Some fish limited by pressure examples: coelocanth, deep sea fish

Temperature Tropics: Constant: 30C Deep water: Constant: 4C Everywhere else, variable. Fluctuations depend on: mixing daily T flux tides tidesThermoclineEffects:OxygenCaCO3 Nutrient uptake Activity Eurythermal, stenothermal

Light Very important to primary producers, visual senses Red end of spectrum absorbed in upper 10m Blue scattered Photic zone: depends on turbidity (suspended particles, cloudiness) Shoreline: <1m Open ocean: ~60m Tropical reefs: ~80 Absolute depth, clear water: 1000km

Oxygen Terms: Anoxic/anaerobic – no O2 dysoxic/dysaerobic – low O2 oxic/aerobic -- oxygenated Oxygen saturation changes with T, t, D 3ppm: limiting 5ppm: “safe”

Oxygen continued Sources:AtmospherePlantsSinks:Decomposition Respiration (animals and plants) Chemical reactions Mechanisms of O2 movement: DiffusionConvection

Diurnal surface O2 variation: T Morning: 85%; afternoon: 115% Seasonal variation Shallow: April: 150% saturation high photosynthesis + low decomp. August: 42% saturation Deep: T control, detrital rain June: 24% saturation Oct: 133% saturation Chesapeake Bay

CO2 and CaCO3 (Carbon Dioxide and Calcium Carbonate) H 2 O + CO 2  H 2 CO 3 Carbonic Acid H 2 CO 3  H + + HCO 3 - Bicarbonte ion H + + HCO 3  2 H + + CO 3 2- Carbonate ion Calcite (Calcium Carbonate) and CO2 CO 2 + H 2 O + CaCO 3  Ca HCO - carbon dioxide + water + calcium carbonate  calcium + carbonic acid

CaCO3 2 phases: calcite (stable) aragonite (unstable) Acropora modern Syringopora Carboniferous

Salinity Dissolved solids Ocean water: 35 ppk 0-1ppk at fresh water input (hyposaline) to 150 ppk in evaporative systems (hypersaline) Sediments buffered Variability from: Tides Seasonality: precipitation Unpredictable storms Salinity changes density Animals: Stenohaline vs. euryhaline Direct effects: osmosis Indirect effects: buoyancy

How does living on land differ from living in the water?

Living in the Water On land: Need structure for gravity Air less dense Respiration, movement, heat loss/gain on land Need water for respiration, reproduction Vision, hearing In water: Buoyancy, support Dense water More O2; drag forces; heat loss/gain in water Vision, hearing

Anableps dovii, the four-eyed fish

Fish Morphology and Depth