aquatic ecosystems
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Aquatic Ecosystems
Ch 7 & more
Aquatic Ecosystem Food Webs
• plankton: tiny organisms that drift with the currents
• basis of all aquatic ecosystems– Phytoplankton
• Autotrophs• Algae
– Zooplankton• Tiny animals or protozoa• Heterotrophs• Eat phytoplankton
http://www.lhup.edu/smarvel/Seminar/FALL_2000/Picking/Picking.htm
Aquatic Ecosystem Food Webs• Nekton = Free-
swimming organisms– Fish, turtles, etc.
• Benthos = bottom-dwelling organisms– Mussels, worms,
barnacles, etc– Often are attached to
bottom surfaces
• Decomposers
Freshwater vs. Saltwater
Salinity = the amount of salt in water•Salt water = marine ecosystems– Coastal ecosystems
• Estuaries• Salt marshes• Mangrove swamps• Barrier islands
– Coral reefs– Open ocean
•Freshwater = no salt – Ponds, lakes & rivers– Marshes and wetlands
Ponds and lakes• No current• Levels are divided horizontally • by amount of light • and proximity to shore• LitLittoral zonetoral zone: (think light) – Lots of life– Near shore, rooted plants provide food– Off shore, phytoplankton are base
• BBenthic zoneenthic zone: Bottom– Decomposers (bacteria)– detrivores (eat small bits of organic matter on bottom)– Filter feeders
• Shrimp, clams, sponges, crabs etc.
http://environment.nationalgeographic.com/environment/photos/freshwater-plants-
animals/#/mexican-water-lilly_289_600x450.jpg
Threats to Ponds and Lakes
Eutrophication (review)1. Excess nutrients enter
water2. Algae bloom,
overcrowd and die3. Bacteria decompose
algae, using up oxygen4. Other organisms die
for want of oxygen
http://www.waterencyclopedia.com/A-Bi/Algal-Blooms-in-Fresh-Water.html
Prevention of Eutrophication (review)
Agricultural:• Buffer zones between farms and waterways• Control of runoff in areas of high manure
concentration• High tech fertilizer application (only as-needed)
Eutrophication PreventionDomestic• Lawn-free landscaping
Eutrophication Prevention
Domestic• Buy phosphate-free products
Eutrophication Prevention
Domestic• Repair leaky sewer and septic systems
Wastewater vs. StormwaterSources of wastewater:• Dishwasher• Washer• Sink• Shower• bathtub• Toilet• In short, anything that goes down the drainWastewater goes down sewer lines to a
wastewater treatment plant
Wastewater vs. StormwaterStormwater• Water that collects outdoors and gets sent
into storm drains• Catch basins are design to collect this runoff
RunoffCatch basins take much more than storm
water• Oils from cars• Industrial chemicals• Soil from construction sites• Nonpoint-source pollution – cannot be
traced back to any single source• Point source pollution: can be traced to
a specific source
Stormwater runoff• Most stormwater goes directly to a
waterway
Combined Sewer• Stormwater and wastewater use same system
of pipes and get run to water treatment plant
http://www.epa.ohio.gov/dsw/cso/csoindex.aspx
Combined Sewer Overflow
• It works…until it rains hard• In heavy rains, the combined stormwater and
wastewater overflow and go directly to the waterways, polluting them
• CSO = combined sewer overflow
Combined Sewer Overflow Treatment
• Extra waste water treatment plant at point where CSO runoff gets to waterway
• Stop-gapBetter solution:• Separate sewers and stormwater systems
Permeability
• The ability to allow substances flow through• A permeable surface allows rain to percolate
(seep) into the ground.– Examples:• Grass or other plants• Gravel• Dirt• Ground cover like pine straw or wood chips
Permeability
• Rain washes/flows over an impermeable surface and does not get absorbed into the ground.– Ex:• Rooftops, • roads, • parking lots
Permeability
permeable impermeable
The more impermeable surfaces we have, the more runoff goes straight into the waterways and takes pollutants with it.
Wetlands• Areas of nearly constant moisture
that contain great biodiversity
• Wetlands are often found in estuaries: “where rivers meet the sea”– Large mostly flat areas – Salinity changes with tides• As tide comes in (gets higher), salinity ↑• As tide goes out (gets lower), salinity ↓
http://bio1152.nicerweb.com/Locked/media/ch52/aquatic-estuary.html
Estuaries
• Nutrient mixing with tides• Salt water is ______ than fresh water• Heavier/denser• Due to tides and salt/fresh water mixing, nutrients
get “trapped” in estuaries.
http://www.wwu.edu/salishsea/estuary.shtml
Estuaries in Georgia
•
Estuaries in Gulf of Mexico
Freshwater Wetlandstwo main types
Marshes• Mostly non-woody plants
such as grasses, reeds and cattails
Swamps• Dominated by trees and
shrubs
swamps
Saltwater swamps are mangroves Freshwater swamp
Trees have “knees” or buttresses, probably for support in mushy ground
http://inchinapinch.com/hab_pgs/marine/mangrove/mangrove.htm
Benefits of Wetlands
1. Filter pollutants2. Control flooding– Act as giant sponge, absorbing and slowing water as it
flows through
3. Buffer shorelines against erosion (absorb impact)4. Spawning grounds, migration stop and habitat
for:– commercially important shellfish and fish– Native species (some rare, endangered)
5. Recreation
Wetlands: Human Impact • Less than ½ of original US wetlands remain• Causes of destruction include– Ports (remember, wetlands are usually in estuaries)– Development (NYC, Miami, Shanghai, New Orleans…etc)
– Dams, levees, canals, channels– Pollution from runoff and wastewater– Non-native plants and animals– Sanitary landfills– Mosquito control (drainage, channelization, poisoning)
• Channelization: digging channels/canals to drain land
Wetlands: Human Impact
• Draining wetlands results in:– Loss of benefits stated earlier– Subsidence: ground sinks due to drying out– Salt water intrusion: as wetlands are drained,
saltwater seeps in from ocean• This is also a cause of further destruction (positive
feedback loop)
Wetland Loss Solutions
• Mitigation program:– Creating wetlands in new areas to replace their
destruction for development (1983)– Mitigation bank: sells newly created wetlands to
developers who have to mitigate
• Disallow wetland destruction for agriculture (1985)
Barrier Islands
• Protect mainland and coastal wetlands
http://geology.rockbandit.net/2008/09/15/how-barrier-islands-such-as-galveston-work/
Barrier islands take the brunt of storms
Tuesday, October 30, 2012Superstorm Sandy: TuesdayA Portion of Harvey Cedars on Long Beach Island, New Jersey is underwater Tuesday, Oct. 30, 2012, a day after Hurricane Sandy blew across the New Jersey barrier islands.http://seattletimes.com/html/photogalleries/nationworld2019559529/
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