Aquatic & Fisheries Ecology

Aquatic = taking place in or on water Fishery = the occupation, industry, or season of taking fish or other aquatic animals (Focus = human use.) Ecology = the study of interactions of organisms with other organisms and with the abiotic environment

Earths Surface 71% water; 29% land Water Volume 96.5% = ocean 1.8% = glacial ice 1.7% = groundwater 0.014% = lakes/streams 0.001% = atmosphere

Water (H 2 0) Characteristics Polar = (+ & -) ends. H-bonds connect molecules; so liquid at room temp. & has high specific heat. (more energy to change temp.) Polar & ionic molecules dissolve well in water. Boils at 100°C; freezes at 0°C Most dense at 4°C Solid H 2 O less dense than liquid H 2 O

pH – Acidity & Alkalinity H 2 O H + + OH - H 2 O + CO 2 H 2 CO 3 H + + HCO 3 - H + = acid (pH 7) pH of rain 5.6 – because of CO 2 in air H 2 O + CO 2 H 2 CO 3 H + + HCO 3 - Alkalinity = the ability of a solution to neutralize (buffer) acids ( high pH) -usually accounted for by HCO 3 - conc. H 2 O + CO 2 H 2 CO 3 H + + HCO 3 - freshwater pH = seawater pH 8.0 (high HCO 3 - /alkalinity)

Salinity Salinity = the total amount of dissolved material in water (Na +, K +, Mg 2+, Ca 2+, & Cl -, Br -, HCO 3 -, CO 3 2- ) Difficult to measure accurately – milligrams per liter (mg/l), parts per thousand (), or conductivity in Siemens per centimeter. Practical Salinity Scale = salinity measured electronically without units Chlorinity = grams per kilogram Cl - Salinity = x Chlorinity

Salinity Marine salinity 35 (32-37) ( 35) Brackish salinity = Freshwater salinity 0.12 (<0.5) Hypersaline waters >37 Source of salts – rock weathering (most ions) ; volcanic activity (source of most Cl - ) Salts concentrated in the world ocean (or isolated terrestrial basins)

Hardness Hardness = mg per liter of Ca 2+ & Mg 2+ soft water = <17.1 mg/l hard water = 17.1 mg/l Primarily concerned with CaCO 3 (limestone). Hard water = greater buffering capacity.

Chemical Processes H 2 O + CO 2 H 2 CO 3 H + + HCO 3 - OH - + H + 2H + + CO 3 2- CaCO 3 solid (limestone) Ca 2+ photo- synthesis 6O 2 + C 6 H 12 O 6 glycolysis + cell. respiration 6H 2 O + 6CO 2 inside a cell light energy ATP energy

Gas Solubility N 2 = 48% of gases in seawater. (78% of atmos.) CO 2 = 15% of gases in seawater AS CO 2. (0.03% of atmosphere) Most CO 2 enters carbonate buffer system, because of this CO 2 is incredibly soluble. O 2 = 36% of the dissolved gases in seawater. (21% of gases in atmosphere; 100x more in atmos.) O 2 & CO 2 solubility decreases as temp. & salinity increase, AND increases as pressure increases.

Dissolved Gas Concentration ABIOTIC determinants Temperature Salinity Pressure BIOTIC determinants Photosynthesis – Can increase O 2 and decrease CO 2 greatly (sometimes to O 2 supersatuation… forming bubbles). Glycolysis & Cellular Respiration – Can increase CO 2 and decrease O 2 greatly (sometimes to the point of anoxia).

Relationships Increasing salinity… decreases gas solubility decreases heat capacity lowers freezing point increases energy for evaporation Increasing temperature… decreases gas solubility increases ion solubility

Light Penetration Light important for photosynthesis. Light does not penetrate water as well as air. (Reds are first filtered out by water, blues last.) Turbidity = amount of suspended material in the water (cloudiness) More turbid = lower penetration of light. Higher turbidity and greater depth = less light over all Greater depth = less red wavelength light

Stratification Thermocline = rapid change in temperature at a specific narrow range of depth Halocline = rapid change in salinity at a specific narrow range of depth Pycnocline = rapid change in density at a specific narrow range of depth (If present, it corresponds to thermocline & halocline.)

Waves Waves occur when energy is transferred to the water from above or below. wind (surface); earthquake (bottom) Energy is transferred efficiently among H 2 O molecules. crest trough wavelength wave height wind

Waves Swell = mature, regular, rounded waves.

Waves Waves dampened by... H 2 O molecule cohesion – small waves Gravity – large waves Wave formation from vigorous energy input often causes peaked crests. Top moves faster than bottom. crest trough wind

Breaking Waves Breaking Wave = top of wave falls over bottom of wave. Wave feels the bottom at ½ wavelength.

Breaking Waves

Internal Waves If the thermo/pycnocline is very narrow, internal waves can develop between the the two layers. Internal waves in the deep, dense layer move much more slowly than surface waves in air. Internal waves can form regular slicks of downwelling water above the wave troughs. Slicks can concentrate plankton.

Internal Waves MORE DENSE LESS DENSE slick

Internal Waves

Regions of a Body of Water Benthic = on, at, or associated with the bottom Pelagic = in or associated with open water away from the bottom.

Substrate/Sediment Substrate = the bottom of a body of water Sediment = particles that accumulate to form a loose substrate. Boulders = >25.6 cm Cobbles Pebbles/Gravel Sand Silt Clay = <0.004 mm Detritus = fragments of dead photosynthesizers

Hydrologic Cycle

Ocean Interface

Groundwater Groundwater = water under the surface of the soil (Surface Waters = above the surface) Water Table = The vertical extent of water saturated soil and/or rock Aquifer = Water contained within porous rock (Contained Aquifer = below water impermeable rock) Groundwater Recharge = entry of surface water into groundwater

Freshwater System

Ogallala Aquifer

Ocean Profile continental shelf continental slope abyssal plain

World Ocean Basin

Surface Ocean Currents Gyre = a large system of rotating currents (5 large global gyres); mostly from winds N. hemis. = clockwise; S. hemis. = counter

Ocean Conveyor Belt Conveyor Belt = a large scale global water circulation driven by density

Upwelling & Downwelling Upwelling = colder denser water comes near surface. -coastal upwelling -equatorial upwelling -deep current upwelling

Upwelling & Downwelling