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 – phytoplankton
Swimming microscopic and macroscopic
organisms – zooplankton
Fish – nekton
Tube 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 zone
What area exhibits variable temperature
and salinity
- Estuaries
Where 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 zone
Where do the worms live?
-the benthic zone
Sunlight
Green
frog
Painted
turtle
Blue-winged
teal
Muskrat
Pond
snail
Littoral zone
Limnetic zone
Diving
beetle
Plankton
Profundal zone
Benthic zone
Yellow
perch
Bloodworms
Northern
pike
Fig. 7.14, p. 165
Nutrient levels in lakes
A newly formed, nutrient poor lake is?
- Oligotrophic
A mature and nutrient rich lake is?
- eutrophic
A middle aged and moderately nutrient
rich (normal) lake is?
- mesotrophic
Sunlight
Much shore
vegetation
High concentration
of nutrition and plankton
Limnetic zone
Salt, sand,
clay bottom
Wide
littoral
zone
Dense fish population
Gently sloping
shorelines
Eutrophic Lake
Fig. 7.15b, p. 166
Sunlight
Little shore
vegetation
Low concentration of
nutrition and plankton
Narrow
littoral
zone
Limnetic zone
Profundal zone
Sparce fish
population
Steeply
sloping
shorelines
Sand, gravel,
rock bottom
Oligotrophic Lake
Fig. 7.15a, p. 166
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
22˚
20˚
18˚
8˚
Epilimnion
Hypolimnion
Thermocline
4˚
4˚
6˚
5˚
4˚
4˚
4˚C
4˚C
Summer
Fall overturn
4˚
4˚
2˚
0˚
4˚
4˚
4˚
4˚
4˚C
4˚C
Winter
Dissolved O2 concentration
4˚
4˚
4˚
Spring overturn
High
Medium
Low
Fig. 7.16, p. 167
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
Rain and snow
Lake
Glacier
Rapids
Waterfall
Tributary
Flood plain
Oxbow lake
Salt marsh
Delta
Ocean
Deposited
sediment
Source Zone
Transition Zone
Water
Flood-Plain Zone
Sediment
Fig. 7.17, p. 168
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