The Estuarine Ecosystem Flashcards
Estuaries?
Semi enclosed areas where fresh water and seawater meet and mix. Coastal transition zone - not everywhere. Represent a close interaction between land and sea. High productivity - most productivity. High biodiversity. Rank among the environments most affected by humans
Coastal plain estuary
Most common, forms as sea level rises and floods existing river valleys e.g. Chesapeake bay, humber, Severn.
Fjord
Forms a sea level rises and floods glacier valleys e.g. Alaska, Canada. Normal glacial features ( u shaped valleys) barrier at the base. Moraine therefore less productive
Bar built estuary
Shallow and separated from open ocean by sand bars deposited parallel to coast by wave action e.g. us gulf coast and east cost
Tectonic estuary
Forms when folding/faulting rocks generates downdropped area. Down movement of the crust. Flooding on tectonic basic e.g. San Francisco Bay
Vertically mixed estuary
Always to do with solidity. - shallow, low volume, net flow from head to toe, isn’t deep enough. Deep water means you can identify different water types. Fresh water going out and saltwater going in.
Slightly stratified estuary
Slightly stratified estuary - salinity increases from head to mouth at all depth. Two distinct layers.
Highly stratified estuary
Deep with upper layer salinity increasing from head to mouth
Salt wedge estuary
Wedge of salty water from ocean moves in under river water - common.
Living in estuaries
Have to cope with salinity. Marine organisms that have adapted however few have. Flucating salinity - need to move around and follow the water. Maintaining salt and water balance the hardest part. Behavioural adaptations
Open water communities
Enter and leave with the tide. Vary with currents/tides/salinity/temperature
Young fish, shrimp etc use as a nursery grounds - high production. Main cities developed around estuaries.
Mudflats communities
Found in lower, intertidal zones. Run off of sediment. Exposed at low tide - organisms experience desication , temperature extremes, predation, salinity change
Informal organisms. Primary producers - diatoms and bacteria. Mixed sediments. Still produce large amounts of productivity.
Low biodiversity. Community Dominated by polychete worms, etc
Salt marsh communities
Extensive area of grassy plants that border estuarine regions in temperate and sub tropical areas. Main primary producer is cordgrass found mostly in intertidal water.
Wetland system. Nutrient/run off soak up.
Mangrove swamp communities
Like salt marshes in the tropics. Not only found on the estuaries. Dominated by mangroves. Flowering land plant adapted to intertidal conditions. Pneumatophores air roots allow gaseous exchange. Most productive
Estuaries productivity
Have represents from the 3 main group responsible for Primary production. Macrophytes , phytoplankton, benthic organisms.
However they are not heterotrophic ( consumption exceeds production) and it’s overall production.
Large amounts of material generated outside the system are imported to the system.
