aquatic ecology. saltwater (marine) ecosystems ocean: estuaries & coastal wetlands barrier...
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Saltwater (Marine) Ecosystems
Ocean:
•estuaries & coastal wetlands
•barrier islands
•coral reefs
•mangroves
Freshwater Ecosystems
•lakes
•rivers & streams
•wetlands
Marine Ecosystems
Economic Services
Climate moderation Food
CO2 absorption Animal and pet feed
Nutrient cycling Pharmaceuticals
Harbors and transportation routes
Waste treatment
Reduced storm impact (mangroves, barrier islands, coastal wetlands)
Coastal habitats for humans
RecreationHabitats and nursery areas Employment
Genetic resources and biodiversity
Oil and natural gas
Minerals
Scientific information Building materials
Ecological Services
NATURAL CAPITAL
Factors Affecting Aquatic Ecosystems• Light (solar radiation)
decreases with depth because of absorption by water, suspended materials, & phytoplankton; essential for photosynthesis
Turbidity (cloudiness) effects light
• Temperaturedecreases with depth because of decreasing energy input from sun; affects dissolved gases, rates of chemical reactions, & where organisms can live;
•Dissolved oxygen- factors that affect DO
• Temperature – less dissolved gasses at warmer temperatures.
• Rate of production through photosynthesis
• Rate of consumption through cellular respiration
• Pressure
•Nutrient availability most limiting macronutrients are phosphorus (P) & nitrogen (N); limiting micronutrients include iron (Fe); essential for growth of phytoplankton.
Factors Affecting Aquatic Ecosystems Cont.
Low tideCoastal Zone
Open Sea
Depth in meters
High tideSun
Sea level
50Estuarine Zone
Euphotic Zone
100
Ph
oto
syn
thes
is
Continental shelf
200
Bathyal Zone 500
1,000
Tw
ilig
ht
1,500
Water temperature drops rapidly between the euphotic zone and the abyssal zone in an area called the thermocline .
Abyssal Zone
2,000
3,000
4,000
Dar
knes
s
5,000
10,000
0 5 10 15 20 25 30
0
Water temperature (°C)
Nitrate Concentrations High concentrations of nitrates found in areas of:
• low productivity (in areas of high productivity- nutrients are quickly utilized by living things)•High upwellings- upwellings bring cold, nutrient rich H2O
How do areas of high nitrates along coast of South America relate to weather unit?
Life zones of the OceanVertical Zones:
Euphotic Zone: 0 - 200 mGreatest amount of light.
(Eu = good, photo = light)
Bathyl Zone: 200 - 4500 m
Abyssal Zone: 4500 - 11,000“marine snow” – dead organisms from above(Abyss= the deep)
Hadal Zone: > 6000m
Benthic Zone = Region along bottom of sea
Benthos = bottom dwelling sea creature.
Pelagic Zone = open seaRegion that is not near the shore or close to the bottom.
• extends from high–tide mark to edge of continental shelf
• entirely within the euphotic zone & includes estuaries, wetlands, mangroves, barrier islands, & coral reefs
•nutrient–rich & the site of most commercial fisheries•high primary productivity: sunlight + nutrients from land & ocean currents
Coastal Zone of the Ocean
Importance
•nutrient rich and high primary productivity
•nurseries for fish & other aquatic animals
•waterfowl & shorebird breeding areas
• filter water pollutants
Estuaries & Coastal WetlandsEstuary: 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
Human Impacts
Estuaries & Coastal Wetlands
• 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
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
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
Barrier Islands
Ocean City, MD
• 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
Coral Reefs
Importance
• high biodiversity: “tropical rain forests of the ocean”
• protect coastlines from storms & high waves
• nurseries for many fish species
• disappearing
Coral Reefs
Vulnerability
• slow growing
• easily disturbed
• thrive only in clear water
Human Impacts
• sediment runoff & effluent
• increased UV radiation (ozone depletion)
• fishing with cyanide & dynamite
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
NATURAL CAPITAL
Freshwater Systems
Ecological Services
Economic Services
Climate moderation Food
Nutrient cyclingDrinking water
Waste treatmentIrrigation water
Flood control
HydroelectricityGroundwater recharge
Habitats for many species
Transportation corridors
Genetic resources and biodiversity
Recreation
Scientific information Employment
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.
Freshwater Ecosystems
Sunlight
Painted turtle
Blue-winged teal
Green frog
Muskrat
Pond snail Littoral zone Plankton
Limnetic zoneProfundal zoneDiving beetle Benthic zone
Northern pike
Yellow perch Bloodworms
Thermal stratification:
during summer
(temperate lakes)
•epilimnion: warm, upper layer of water
•thermocline: zone of lake where temperature changes rapidly with depth
•hypolimnion: colder, denser lower layer of water can be depleted of oxygen in eutrophic lakes
LAKES
Overturn: spring & fall (temperate zone lakes)
•upper layer of water cools and sinks,
•winds mix layers
•redistributes oxygen & temperature evenly
•redistributes nutrients from the lower layers
LAKES
Watershed: the land area that delivers water, sediment, & dissolved substances to a water body.
Zones
• source zone: cold, clear, fast–running streams in upper watershed (headwaters)
• transition zone: middle part of watershed, where streams widens & join, flow slows, water temperature increases
• flood plain zone: many streams join to form a broad, slow–moving, meandering river in lower watershed
Streams & Rivers
Waterfall
LakeGlacierRain and
snowRapids
Source Zone
Transition Zone
Tributary
Flood plainOxbow lake
Salt marsh
Delta Deposited sediment
Ocean
WaterSediment
Floodplain Zone
WetlandsLands covered with fresh water all or part of the time (excluding lakes).
Wetland functions
• 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.