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