Estuary: Partially enclosed/sheltered coastal regions where rivers meet the sea

Salt marshes: special plant associations that border temperate and subarctic estuaries and protected marine shores throughout the world (intertidal)

Mangrove Forest: tropical inshore (protected) communities not necessarily associated with estuaries (intertidal)

Sea Grass Beds: subtidal areas of lush growth consisting of aquatic grasses

Saltmarshes, Mangroves and Seagrasses in Estuaries and other Coastal Zones

Therefore, estuaries are embayments which often are associated with intertidal salt marshes and mangrove forests and subtidal sea grass beds…..

...but sea grass beds and mangrove forests also exist outside of estuaries.

Saltmarshes, Mangroves and Seagrasses in Estuaries and other Coastal Zones

Salt marshes are prevalent where there are slightly sloping shorelines

Worldwide Distribution of Mangrove Species

Possible Explanations for this “anomalous” pattern: -Center of Origin: mangrove taxa originated in the indo-west Pacific then spread

- Vicariance : peak does not correspond to origin; continental drift resulted in skewed distribution

Fossil record of mangrove and 8 genera of snails that live with them are consistent with vicariance hypothesis

30 species in SE Asia to < 5 spp. in the Caribbean

Coastal Plain Estuaries: formed when sea level increases, flooding lowlands and river mouths.

Chesapeake Bay Delaware Bay

Bar Built Estuary: accumulation of sand bars builds up sand bars and barrier islands ex. Texas Coast, North Carolina barrier islands Indian River Lagoon in Florida.

North Carolina

Tectonic Estuary: subsidence of land due to movement of crust creates an estuary

ex. San Francisco Bay

--Subject to large fluctuations in salinity due to runoff, tidal flow and currents

High Tide

Low Tide

Sedimentation from rivers invariably contributes to a soft muddy bottom. Anoxic sediments are a major factor in the community

•  Habitat: birds, mammals, fish, crabs •  Nursery: including commercially important species •  Productivity: 4 to 10x a cornfield of the same size •  Water Filtration: sediment and nutrient loads •  Flood Control: porous resilient soils absorb flood waters and dissipate storm surges

There are 102 estuaries in the U.S.

What Contributes to High Estuary Productivity?

Estimated sources of Nitrogen to Chesapeake Bay

_____________________________ Sources % of total Loading

Waste Water 23 Atmosphere Ammonium 14 Nitrate 25 Fertilizer 34 Animal Waste 4

Ranges of Net Primary Production by Phytoplankton and macrophytes in various coastal environments

NPP (g C/ m2/ day Phytoplankton Estuaries Bays Lagoons Shelf Macrophytes Seagrasses Mangroves Salt marshes Kelp Forests

0.2 - 1.5 0.1 - 1.0 0.2 - 0.7 0.4 - 0.9

0.2 - 18.5 0.0 - 5.7 0.2 - 36.5 0.4 - 9

Life cycle of a mangrove Mangrove Forests

support a variety of fauna and floral assemblages

Zonation: not consistent between sites yet certain species are noted to occupy the seaward fringes while others occur in upland riches; however discrete zones are difficult to identify

Mangroves Export significant amounts of nutrients to adjacent sea grass meadows, coral reefs and the open ocean

-- 30-80% of fallen leaves, branches consumed rapidly by

crabs etc.

-- < 50% is decomposed by microbial activity

-- amount exported is highly variable and depends on local

hydrodynamics

Natural: treefalls lightning strikes cyclonic storms

Anthropogenic: selective extraction clear cuts oil spills organic enrichment

Natural disturbances are either large in intensity or

long in duration but not both.

Human disturbances occur more frequently, and tend

to have both large intensities and longer

duration

Loss of mangrove habitat worldwide is extensive In Philippines and Ecuador, >50% of mangrove forests have been converted to shrimp ponds

Logging for construction and boat building is also intensive. Forest management and reforestation can be successful, but in all cases there seems to be an escalating degradation of the natural system.

Striped parrotfish, blue striped grunt, schoolmaster

• Stripe parrotfish functionally dependent on mangroves; has suffered local extinctions in areas of mangrove loss

• Biomass of other commercially important species is more than doubled when adult reef habitat is connected to mangroves

Estuaries in temperate and subarctic regions are bordered by extensive grassy areas

Dominated by grasses

Salt marshes are prevalent where there are slightly sloping shorelines

Tidal flooding and high salinity fluctuations

Organic matter in water logged soils becomes anoxic

Adventitious roots near the soil surface

Plants accumulate salt in tissues

Excrete salt at roots and through leaves

Animals have to be Euryhaline

Strong elevational zonation driven by interspecific competition along gradients of waterlogging and salinity

In New England: two species of Spartina segregate on basis of ability to oxygenate their roots; each dies if transplanted to lower elevations but survives if transplanted to higher levels

Food Webs

A considerable amount of production in estuaries goes into detritus and is exported!

Few things feed on living sea grass, but the meadows serve as a habitat for a variety of animals

Sea Hare Sea Grass Epifauna

..and many detritivores eat partially decomposed seagrass

Food Web of a Sea Grass Community

Seagrass meadows are among the most

disturbed coastal ecosystems