uic edu aquatics

7/26/2019 Uic Edu Aquatics

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Exam 3 lecture 1 Nyberg BioS 101 UIC 1

Aquatic ecosystemsAquatic ecosystems

All life is dependent on WATER.

Salt-

and fresh-

water ecosystems haveimportant differences because the

concentration of solutes in organisms is

between pure water and seawater.


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READING ASSIGNMENTREADING ASSIGNMENT

Chapter 50.2

A review of the Water lecture, x1 05, may

help to understand this lecture.

I have included more local information and

more on the impact of sewage on aquatic

ecosystems than your text.


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AQUATIC ECOSYSTEMSAQUATIC ECOSYSTEMS

Freshwater

Lakes and Ponds

too deep for emergent plants

Wetlands

ephemeral or with emergent plants

Streams and Rivers

flowing water

Saltwater

Estuaries

Oceans -

huge, importance of tides


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Water CycleWater Cycle

Rain drops condense out of air when watervapor is saturated as temperature cools.

Ice and Groundwater are big fractions of the

earths freshwater.

Rivers transport materials, including ions, to

the ocean (more rain over land than ocean).

Energy from sun evaporates water.


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Freshwater versus SaltwaterFreshwater versus Saltwater

Rain has dissolved gases, i.e., CO2, that make itacidic, but no mineral cations (except from dust).

Saltwater is about 3% salt and has many cations.

Cells of organisms have a concentration of cationsless than saltwater, but greater than freshwater.

Organisms in freshwater have to pump water outof their cells, while organisms in saltwater have to

do work to keep water inside their cells.


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Life evolved in SaltwaterLife evolved in Saltwater

Among the reasons life is thought of haveevolved in saltwater is:

Most water on earth is in the oceans

Many phyla of animals live in saltwater and

fewer live in freshwater


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Water density and lake turnoverWater density and lake turnover

Water is most dense at 4 C, e.g., ice floats. In temperate areas, the cold surface waters

reach the same density as the bottom water

in the spring and the water is mixed by wind.

In fall the surface waters (with O2) sink to

the bottom of a lake as they reach 4 C,bringing dissolved oxygen to the bottom.


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ThermoclinesThermoclines and Lakeand Lake

TurnoverTurnover


Abrupt change of temperature with depth is known as thermocline.


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Lake MichiganLake Michigan

6th

largest freshwater lake in the world 3rd largest of the Great Lakes

Ave depth = 85 m, Max = 282 m = 925 feet Volume = 4,920 km3, retention time 99 years

Total drainage basin = 118,000 km

2

IL drainage basin = 300 km2


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Lake MichiganLake Michigan


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Water CribWater CribWhere Chicago Water Comes FromWhere Chicago Water Comes From


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Fish of Lake MichiganFish of Lake Michigan

Lake trout, Whitefish and Perch are thenative fish of Lake Michigan

The fauna has been dramatically altered by

invasions and deliberate introductions.

Invaders

Sea Lamprey, Alewife, Round Gobi

Introductions

Smelt, Coho Salmon, Chinook Salmon


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WetlandsWetlands

Kankakee Marsh in IN and Lake Calumetwere huge wetlands of Chicagoland. The

marshes have largely been drained or filled.

Wetlands have high levels of biological

activity because of the availability of water.

An ephemeral wetland is one that is bothwet and dry in same year.



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Streams and RiversStreams and Rivers

Streams and rivers have a channel. Greater drop in elevation per unit length

make the water flow faster.

Rivers naturally meander, especially whenelevation loss is slow.

Many flowing water organisms stay in oneplace and let the current bring food to them.


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Transportation by RiversTransportation by Rivers

People have used rivers to get themselves tonew places for a long time.

People have also used flowing water to get

rid of waste. Sanitary sewers bring water from toilets to a

processing place where growth oforganisms removes nutrients from thewater before it leaves the facility.


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EstuaryEstuary

Rivers eventually flow into oceans. Frequently, sediments from the river

accumulate to form shallow areas near the

mouth of the river known as estuaries.

Emergent plants and the mixing of nutrients

from the river and the ocean make estuariesvery productive.


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Dead ZonesDead Zones

Nutrients from the river are not always used up inthe estuary.

Nitrogen from the Mississippi River has resulted in

increased algal growth (productivity) in the Gulfof Mexico. Old algae sink to the bottom and their

decomposition depletes the oxygen near the bottom.

Fish flee the water without oxygen and from the

fishermans point of view it is a dead zone.


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OceansOceans

Oceans cover almost 3/4ths of the earthssurface. Most of the water on earth issaltwater.

At 10 m under the water surface the pressureis equal to 1 atmosphere.

Sunlight penetrates ocean to only 40 m anddeep areas are dependent on currents for thevery limited amount of oxygen available.


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TidesTides

The gravitational attraction of the mooncreates tides in the ocean.

There are two high tides and two low tides

per 25 hour period.

The intertidal zone is the area between the

high tide and low tide. Wave action keepsplants from growing on sand beaches.


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Shallow OceanShallow Ocean

Most continents are surrounded by a shelfof rock that means the ocean is relativelyshallow (less than 200 m) near the shore.

Continental shelf waters have higherproductivity because of nutrients from rivers.

Continental shelfs are where almost all theocean fishing occurs.


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OverfishingOverfishing

There have been many examples ofoverfishing.

Sardine fishery of Monterey CA

Lake trout in Lake Michigan

Herring in the North Sea

Cod off MA and Canada

Some overfished populations recover afterfishing stops, but most have not recovered.


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Oxygen in WaterOxygen in Water

Oxygen is not very soluble in water, 16 mg/l. If the water contains organic compounds

metabolism can quickly use all the oxygen in

the water, creating anaerobic conditions.

BOD, biological oxygen demand, measures

how much oxygen would be used inrespiration of organics in water.


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Energy Flow in Aquatic SystemsEnergy Flow in Aquatic Systems

Streams and small ponds typically getconsiderable inputs from the surrounding

terrestrial environment, e.g., leaf litter.

Phosphorus is usually the nutrient limiting

growth of algae. Input from humans has

resulted in blooms of algae. Increased growthof organisms (productivity) is called

eutrophication.


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EutrophicationEutrophication

Clear water implies that the density of fineparticles, including small organisms, is nothigh. Such lakes, including Lake Michigan,

are called oligotrophic. Lakes with an abundance of by small

organisms (productivity and resulting high

turbidity) are called eutrophic.


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VocabularyVocabulary

Freshwater Saltwater

Eutrophication

Algal bloom

Biological Oxygen

Demand, BOD

Dead zone Overfishing

Estuary

Turnover

Oligotrophic

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