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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
Say hello to my little friends
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