Aquatic Ecology

Chapter 6

Coral Reefs

What do coral reefs require?Answer – dissolved oxygen, light and

nutrients

What threatens coral reefs? (3)Chemical pollution, global warming,

extra UV from ozone hole, excess sediment from rivers (soil erosion), human contact

Coral Reefs

What percent of reefs is estimated to be destroyed by human intervention?

10 percent

What about estuaries and wetlands?About 50%(US) through filling, sewage,

runoff pollution, and diversion

Categories of organisms

Floating algae – phytoplanktonSwimming microscopic and macroscopic

organisms – zooplanktonFish – nektonTube worms, crabs - benthos

Reasons oxygen varies in water

Number of consumers (respiration)Number of producers (photosynthesis)Temperature (cold holds more)Turgidity (rough water dissolves more)Number of decomposers (bacteria can

take up a lot of oxygen)

Salt water areas

What zone is on the continental shelf?- the coastal zoneWhat area exhibits variable temperature

and salinity- EstuariesWhere would you find a mangrove?- tropical coastal estuaries

Fig. 7.7, p. 157

Salt water areas

What is the dim or twilight area of the open sea called?

- bathyal zone

What is the area with the highest photosynthetic rate in the sea called?

- euphotic zone

Fresh water areas

Where does photosynthesis take place in lakes?

- the limnetic zone, of course!Where do fish who like cool, dark water

reside?- the profundal zoneWhere do the worms live?-the benthic zone

Fig. 7.14, p. 165

Sunlight

Paintedturtle

Greenfrog

Pondsnail

Blue-wingedteal

Muskrat

Plankton

Northernpike

BloodwormsYellowperch

Divingbeetle

Littoral zone

Limnetic zone

Profundal zone

Benthic zone

Nutrient levels in lakes

A newly formed, nutrient poor lake is?- OligotrophicA mature and nutrient rich lake is?- eutrophicA middle aged and moderately nutrient

rich (normal) lake is?- mesotrophic

Fig. 7.15b, p. 166

Sunlight

Much shorevegetationMuch shorevegetation

High concentrationof nutrition and plankton

Widelittoralzone

Limnetic zone Dense fish population

Gently slopingshorelines

Salt, sand,clay bottom

Eutrophic Lake

Fig. 7.15a, p. 166

Sunlight

Limnetic zone

Profundal zone

Sand, gravel,rock bottom

Oligotrophic Lake

Sparce fish population

Low concentration ofnutrition and plankton

Narrowlittoralzone

Steeplyslopingshorelines

Little shorevegetation

Overturn

When does overturn happen is a lake?When the weather changes from warm to

cold, or cold to warm, so in spring and fall

Which season produces the most profound thermoclines?

summer

Fig. 7.16, p. 167

Epilimnion

Hypolimnion

ThermoclineSummer Fall overturn

22˚20˚

18˚8˚

6˚5˚

4˚C

0˚2˚

4˚4˚

4˚

4˚C

Winter Spring overturn

4˚4˚

4˚4˚

4˚

4˚C

Dissolved O2 concentration High Medium Low

4˚4˚

4˚4˚

4˚

4˚C

It’s okay to destroy when?

If you ruin a wetland for agriculture (the number one reason), what says you have to build a new one somewhere else?

Mitigation banking – it is an agreement to restore or create new in another location whatever wetlands you ruin

Fig. 7.17, p. 168

Rain and snow

Water

Sediment

Lake Glacier RapidsWaterfall

TributaryFlood plain

Oxbow lake

Salt marsh

Delta Ocean

Depositedsediment

Source Zone

Transition Zone

Flood-Plain Zone

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