Marine Bio: estuaries

estuary

semi-enclosed area where freshwater and seawater mix

environmental conditions vary based on riverine vs. tidal input

more marine

high tide or low river input…

more riverine

low tide or high river

high

variation results in low species diversity, but high nutrient input results in __ biomass

1. drowned river valley

2. bar built estuary

3. tectonic estuary

4. fjords

what are the 4 types of estuaries?

drowned river valley

• most common type

• formed by flooding of river mouth by rising sea levels

• ex chesapeake bay

Bar- built estuary

• accumulation of sediment into sand bars or barrier islands

• ex Cape hatteras and the outer banks

• well developed along flat costal plain and wide continental shelves

• dominated by anoxic mud or fine sand sue to wide continental shelves

Tectonic estuary

• land subsidence from movement of crust

• ex San Francisco Bay

• constrained on active tectonic margins

Fjords

• deep valleys cut by retreating glaciers

• ex. norwegian coast

• dominated by large sand, cobbles, gravel

salt wedge

Horizontal and verical components from this where heavier saltwater penetrates further into estuary along bottom, and lighter freshwater penetrates further offshore on surface

euryhaline

organisms that tolerate a wide range of salinities

osmoregulators

maintains internal concentrations of salinity

osmoconformers

match internal concentrations

salt marshes

dominated by spartina cordgrasses in temperate zones, high primary production due to nutrient input/recycling and is a nursery ground for many fishes.

Mangrove Forests

tropical and subtropical replacement for salt marshes, biodiversity hotspots for marine and terrestrial species, provides protections of habitats from storms and heavy wave erosion