Aquatic Ecology Life of the Wet Things. Marine vs. Fresh Marine = Salt water –Estuaries, Coastlines, Coral reefs, Coastal marshes, Deep ocean Freshwater

Aquatic Ecology

Life of the Wet Things

Marine vs. Fresh

• Marine = Salt water– Estuaries, Coastlines, Coral reefs,

Coastal marshes, Deep ocean

• Freshwater = Non-salty water– Lakes, Ponds, Stream, Rivers, Inland

wetlands

Major Types of Aquatic Life

• Plankton – Free floating

• Nekton – Strong swimming

• Benthos – Bottom dwelling

Advantages of Living in Water

• Natural buoyancy– Less energy spent on support

• Usually limited fluctuations of temperature

• Nutrients usually available

• Waste/toxins diluted

Limiting Factors of Life at Different Depths

• Three major zones– Surface

– Middle

– Bottom


• Life limited by following factors at different depths– Temperature

– Sunlight

– DO

– Nutrients


• Temperature drops as depth increases


• Sunlight can only penetrate about 100ft (30m)– Euphotic Zone


• DO– Varies by temperature and depth

– Comes mostly from atmosphere

– Can be added to by producers

– Depleted by consumers



• Nutrients– Affected by upwelling

– Phosphorus (phosphates) most limiting in freshwater

– Nitrogen (nitrates) most limiting in saltwater

Saltwater Life Zones

• Importance of oceans– 71% of planet– Heat sink– Major role in hydrologic cycle– Has a somewhat large influence in the

earth’s weather patterns• Ok, not so large, more like HUGE

– Gigantic reservoir for CO2


• Two major life zones– Coastal Zone

• On top of the continental shelf• 10% of ocean/90% of ocean life• High primary and net productivity

– Open Ocean




• Estuaries and Tidal Zones– Salt and freshwater mix

• Temperature and salinity vary– Runoff– Tidal flow

• Huge cleaning affect on environment


• Coastal Wetlands– Covered by salt water most of the year

– Breeding grounds/habitat for wildlife

– Filters waste/toxin

– Buffers shores against damage

– Bays, Mud flats, Salt marshes


• Rocky and Sandy Shores– Intertidal Zone

• Between low and high tide

– Rocky shores• Pounded by waves, but still lots of life

– Barrier beaches• Life must dig


• Human impact on coastal zones– 2/3 of human life live within 100 miles of

a coast

– California has lost 91% of its original coastal wetlands


• Coastal wetlands very vulnerable to pollution– Easy to trap pollutants

• Coral reefs decreasing due to human destruction


• Open ocean– Three life zones based on penetration of

sunlight• Euphotic• Bathyal• Abyssal


• Euphotic– Photosynthesis takes place

– Low nutrients

– High DO


• Bathyal and abyssal zones– COLD– Low DO– High nutrients– Life includes

• Deposit feeders• Filter feeders

– Tragedy of Commons

Things to Remember While Googling

• Its abyssal, not abysmal.

Freshwater Life Zones

• Dissolved salt <1% by volume

• Two types– Standing

– Flowing


• About 1% of earth’s surface, but 41% of known fish


• Closely connected to their surrounding terrestrial biomes.– Why?


• Dissolved salt <1% by volume

• Two types– Standing

– Flowing


• About 1% of earth’s surface, but 41% of known fish


• Closely connected to their surrounding terrestrial biomes.– Why?

Freshwater Lakes

• Lake Zones

Freshwater Lakes

• Littoral zone– Shallow– Near shore– Rooted plants stop growing outside the zone– Rich in nutrients– High in biological diversity

• Rooted plants, decomposers, and the usual suspects

Freshwater Lakes

• Limnetic zone– Like the euphotic zone

– Enough light for photosynthesis• Limits depth of limnetic zone

– Starting with plankton, simple food web

Freshwater Lakes

• Profundal zone– Deep, open water

– Too deep for photosynthesis

– Fish only

Freshwater Lakes

• Benthic zone– It’s the bottom.

– Mostly decomposers and detritus-feeders

Types of Freshwater Lakes

• Two types– Oligotrophic

– Eutrophic


• Oligotrophic– Poorly nourished

Freshwater Lakes


• Oligotrophic– Deep with steep

sides

– Crystal-clear blue or green water


• Eutrophic– Well-nourished

Freshwater Lakes


• Eutrophic– Lots of nutrients for producers

• Nitrates and phosphates

– Usually shallow and murky

– During summer, bottom may have low DO

Season Changes in Lakes

• Water is cool, especially when frozen– Makes water unique

– Also helps lakes survive wickedly cold winters• Wickedly meaning not like “Mr. Williamson,

it’s cold in here” or “It’s freezing outside in the F-quad”



• Lake layers– Epiliminon

– Thermocline

– Hypoliminon


• Winter– Top layer freezes

• Insulates lower layers from “wicked” cold• DO ok in epiliminon, not so good in

hypoliminon



• Spring– Ice melts and warms, reaching max

density

– Sinks forcing nutrient rich water from bottom• Helped by winds

– Spring overturn



• Summer– VERY definite stratification

– Causes bottom to loose DO and nutrients



• Fall– Epiliminon cools and becomes more

dense

– Sinks, causing cooler, nutrient rich water to rise

– DO good everywhere

Freshwater Streams and Rivers

• Consists of runoff

• Watershed


• Three zones– Headwater or source zone

– Transition zone

– Flood plain zone


• Source zone– Cold water

– Fast moving

– Lots of DO

– Organisms well adapted to environment




• Transition zone– Deeper channels

– Slower water

– Warmer water


• Flood plain zone– Slow moving

– Murky


• Importance of inland wetlands– Food source and habitats

– Improved water quality

– Reduced flooding and erosion

– Replenish groundwater


• Human impact– Loss of wetlands due to

• Agriculture (80%)• Mining• Forestry• Oil/gas extraction• Urban development


• Mitigation banking– Replacing lost wetlands with equal area

of sime type• Doesn’t work well


• Best course of action– Prevention

Aquatic Life Zones

• Why are they important?

• How do humans impact them?

• How does species diversification relate?

Documents

Aquatic Ecology Life of the Wet Things. Marine vs. Fresh Marine = Salt water –Estuaries, Coastlines, Coral reefs, Coastal marshes, Deep ocean Freshwater