1. Aquatic Ecology

2. Factors Affecting Aquatic Ecosystems
Light decreases with depth.
- Only 1% of light below 200 m
- No light below 1000 m
Turbidity (cloudiness) affects light.
Temperature decreases with depth due to decreasing energy input from sun.li

3. Euphotic Zone Continental shelf
High tide
Low tide
Sun
Depth in meters
Coastal Zone
Open Sea
Sea level
Photosynthesis 50
Euphotic Zone
Estuarine Zone
100
Continental shelf
200
500
Bathyal Zone
Twilight
1,000
1,500
2,000
Water temperature drops rapidly between the euphotic zone and the abyssal zone in an area called the thermocline .
Abyssal Zone
3,000
Darkness
4,000
5,000
10,000 5 10 15 20 25 30
Water temperature (°C)

4. Discuss with your table partner:
Study the pattern of oxygen with depth.
The red line represents approximately the start of the aphotic (no light) zone.
What process accounts for the depletion of oxygen at this depth?
Why is the level of oxygen higher closer to the surface (besides diffusion of O2 into the H2O)?
Decomposition of organic matter (most of which comes
from above) by aerobic organisms depletes the oxygen.
Enough light for photosynthesis which adds oxygen.

5. Discuss with your table partner:
Temperature and pressure also affect the levels of dissolved oxygen and other gases. How does temperature affect the amount of dissolved gas? How does pressure affect the amount of dissolved gas? (Consider what happens when you release the pressure on a sealed bottle of soda.)
Temperature varies inversely with maximum DO.
Pressure varies directly with maximum DO. More dissolved gas at higher pressure.

6. Factors Affecting Aquatic Ecosystems
Nutrient availability most limiting macronutrients are phosphorus (P) & Limiting micronutrients include iron (Fe); essential for growth of phytoplankton.
A failed experiment to increase the carbon stored in the ocean by seeding it with iron to stimulate phytoplankton growth did not work because it also caused a bloom of toxic diatoms.

7. Discuss with your table partner:
Study the pattern of nitrate levels with depth.
What accounts for the increase in nitrates, which corresponds approximately with the lower levels of oxygen?
Decomposition of materials (much of which falls from above) provide available nitrates.
Why are lower levels of nitrates not available closer to the surface?
Greater rate of uptake of nitrates and other nutrients. Phytoplankton use up much of the nitrates.

8. Discuss with your table partner:
Note that in most locations, the surface has low levels of nitrates. Relate the areas of higher nitrates off the west coast of South America to our weather unit.
How do areas of high nitrates along coast of South America relate to weather unit?
Location of upwelling that bring nutrient-rich water from deeper ocean .

9. Life zones of the Ocean Vertical Zones: Euphotic Zone: 0 - 200 m
Greatest amount of light.
(Eu = good, photo = light)
Bathyl Zone: m
Abyssal Zone: ,000
“marine snow” – dead organisms from above
(Abyss= the deep)
Hadal Zone: > 6000m

10. Benthic Zone =
Region along bottom of sea
Benthos =
bottom dwelling sea creature.
Pelagic Zone = open sea
Region that is not near the shore or close to the bottom.

11. Marine (salt water) Ecosystems
NATURAL CAPITAL
Marine (salt water) Ecosystems
Marine Ecosystems
Ecological Services
Economic Services
Climate moderation
Food
CO2 absorption
Animal and pet feed
Nutrient cycling
Pharmaceuticals
Waste treatment
Harbors and transportation routes
Reduced storm impact (mangroves, barrier islands, coastal wetlands)
Coastal habitats for humans
Recreation
Habitats and nursery areas
Employment
Oil and natural gas
Genetic resources and biodiversity
Minerals
Scientific information
Building materials

12. Estuaries & Coastal Wetlands
Estuary: where seawater mixes with freshwater from land, generally at the mouth of a river
Coastal wetland: areas of coastal land covered all or part of the year with salt water
Brackish= mix of salt water and fresh
Importance
nutrient rich and high primary productivity
nurseries for fish & other aquatic animals
waterfowl & shorebird breeding areas
filter water pollutants

13. Estuaries & Coastal Wetlands
Human Impacts
world has lost over half of its estuaries & coastal wetlands
percentage lost in the U.S. even higher. Most lost to coastal development
causes of degradation: urban runoff, sewage treatment plant effluent, sediment & chemical runoff from agricultural lands

14. Barrier Islands
Barrier Islands: long, thin, low offshore islands of sand that run parallel to the shore. They do not remain stationary over time.
Importance
protect mainland from offshore storms
shelter inland bays, estuaries, & wetlands

15. Barrier Islands Human Impacts Development on barrier islands
destroys dunes & dune
vegetation
causes beach erosion
(through trying to keep
islands in place)
destroys or disturbs wildlife habitat (e.g., some endangered birds nest on barrier islands)
Protecting barrier islands
jetties & seawalls
beach replenishment
replanting dune vegetation, controlling development
Ocean City, MD

16. Coral Reefs reefs formed by mutualism between polyps & algae
reefs built as colonies of polyps secrete limestone; hard deposits remain when the polyps die
reefs located in coastal zones of tropical oceans

17. Coral Reefs Importance
high biodiversity: “tropical rain forests of the ocean”
protect coastlines from storms & high waves
nurseries for many fish species
disappearing
Human Impacts
sediment runoff & effluent
increased UV radiation (ozone depletion)
fishing with cyanide & dynamite
Vulnerability
slow growing
easily disturbed
thrive only in clear water

18. Mangrove Swamps Salt-tolerant trees & shrubs
Warm tropical coastal areas
Too silty for coral reefs
Protect coastlines from
erosion, especially during
typhoons & floods
Trap nutrient-rich sediments
Provide habitat for fish, birds,
invertebrates, and plants

19. Freshwater Ecosystems
Lakes
Littoral zone: shallow area near the shore, to the depth at which rooted plants stop growing.
Limnetic zone: open, sunlit, surface layer away from the shore. Depth is the limit of light penetration.
Profundal zone: deep, open water where there is no light penetration.
Benthic zone: the bottom of a lake; inhabited by insect larvae, decomposers, & clams.

20. Sunlight
Painted turtle
Blue-winged teal
Green frog
Muskrat
Pond snail
Littoral zone
Plankton
Limnetic zone
Diving beetle
Profundal zone
Northern pike
Benthic zone
Yellow perch
Bloodworms

21. NATURAL CAPITAL Freshwater Systems Ecological Services
Economic Services
Climate moderation
Food
Nutrient cycling
Drinking water
Waste treatment
Irrigation water
Flood control
Hydroelectricity
Groundwater recharge
Habitats for many species
Transportation corridors
Genetic resources and biodiversity
Recreation
Scientific information
Employment

22. Discuss with your table partner:
Describe the normal pattern of temperature (and density) with depth in a lake in the summer. How does this pattern result in stratification (layers)?
Upper layer is warmer. Since this warmer layer is less dense it remains on the top.
epilimnion: warm, upper layer
epi= above
thermocline: zone where temperature changes rapidly
hypolimnion: colder, denser lower layer hypo= below

23. Discuss with your table partner:
In temperate locations, there is often a turnover over water in the Spring and Fall, which can help redistribute nutrients and oxygen. Explain why these overturns occur.
spring & fall (temperate zone lakes)
When the surface water cools in the Fall it becomes more dense and sinks.
In the Spring, as ice melts it becomes more dense and sinks.

24. Video: Overturn in Temperate Lakes

25. Atmosphere vs. Bodies of Water
In the atmosphere, there is more heating at the bottom. (Not much blocking of light by the atmosphere). - This heating at the bottom creates convection currents such as the Hadley Cells. In bodies of water, most of the heating is at the surface since light can not penetrate very far into the more dense water. - This often leads to thermal stratification.

26. Wetlands Wetland functions Human impacts: Lands covered with
wildlife habitat, especially for waterfowl & amphibians
filter sediments & pollutants from runoff , “nature’s kidneys”
flood attenuation
Human impacts:
some states have lost over 90% of their wetlands by filling or draining.