Aquatic & Fisheries Ecology
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
Earth’s Surface71% water; 29% land
Water Volume96.5% = ocean
1.8% = glacial ice
1.7% = groundwater
0.014% = lakes/streams
0.001% = atmosphere
Water (H20) 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°CMost dense at 4°C
Solid H2O less dense than
liquid H2O
pH – Acidity & AlkalinityH2O ↔ H+ + OH-
H2O + CO2 ↔ H2CO3 ↔ H+ + HCO3-
↑H+ = acid (pH<7); ↓H+ = base (pH>7) pH of rain ≈ 5.6 – because of CO2 in air
H2O + CO2 → H2CO3 → H+ + HCO3-
Alkalinity = the ability of a solution to neutralize (buffer) acids (≠ high pH)-usually accounted for by HCO3
- conc. H2O + CO2 ← H2CO3 ← H+ + HCO3
-
freshwater pH = 5.5-8.5 seawater pH ≈ 8.0 (high HCO3
- /alkalinity)
Salinity Salinity = the total amount of dissolved
material in water (Na+, K+, Mg2+, Ca2+, & Cl-, Br-, HCO3
-, CO32-)
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 ‰ = 1.806 x Chlorinity ‰
SalinityMarine salinity ≈ 35 (32-37) (≈ 35‰)
Brackish salinity = 0.5-32Freshwater 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 Ca2+ & Mg2+
soft water = <17.1 mg/l hard water = ≥17.1 mg/l Primarily concerned with CaCO3
(“limestone”).Hard water = greater buffering capacity.
Chemical Processes
H2O + CO2 H2CO3 H+ + HCO3-
OH- + H+
2H+ + CO32-
CaCO3 solid (limestone)
Ca2+
photo-synthesis
6O2 + C6H12O6
glycolysis +cell. respiration
6H2O + 6CO2 inside a
cell
lightenergy ATP
energy
Gas Solubility N2 = 48% of gases in seawater. (78% of
atmos.) CO2 = 15% of gases in seawater AS CO2.
(0.03% of atmosphere)
Most CO2 enters carbonate buffer system, because of this CO2 is incredibly soluble.
O2 = 36% of the dissolved gases in seawater. (21% of gases in atmosphere; 100x more in atmos.)
O2 & CO2 solubility decreases as temp. & salinity increase, AND increases as pressure increases.
Dissolved Gas Concentration ABIOTIC determinants
TemperatureSalinityPressure
BIOTIC determinants
Photosynthesis – Can increase O2 and decrease CO2 greatly (sometimes to O2 supersatuation… forming bubbles).Glycolysis & Cellular Respiration – Can increase CO2 and decrease O2 greatly (sometimes to the point of anoxia).
RelationshipsIncreasing 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 H2O molecules.
crest
trough
wavelength
waveheight
wind
http://www.classzone.com/books/earth_science/terc/content/visualizations/es1604/es1604page01.cfm?chapter_no=visualization
Waves Swell = “mature”, regular, rounded
waves.
Waves Waves dampened by...
H2O 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 Waveshttp://www.youtube.com/watch?v=5iN_Cs0Mdfg&feature=related
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
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 cmCobblesPebbles/GravelSandSiltClay = <0.004 mm
Detritus = fragmentsof 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
http://www.youtube.com/watch?v=uQRvN6MUajE
Freshwater System
Ogallala Aquifer
Ocean Profile
continentalshelf
continentalslope
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
http://www.youtube.com/watch?v=Hu_Ga0JYFNg
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
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