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/