Estuaries are semi-enclosed bodies of water where freshwater from rivers meets and mixes with saltwater from the ocean. They represent a close interaction between land and sea and are among the most productive environments on Earth. Estuaries contain distinct communities that are adapted to the mixing of fresh and salt water and the tidal fluctuations, including open water, mudflats, salt marshes, and mangrove forests. Organisms in the intertidal zone between high and low tide lines have adaptations to withstand periods of wetness and dryness from the tides.

1. Estuaries
Where Rivers Meet the Sea

2. Rivers connect to ocean
 Estuaries are where
the nutrient outflow of a
river meets the ocean.
 Estuaries are incredibly
productive – meaning
lots of producers!!
 The cloudy water here
in Galveston bay is
NOT dirt!!!
 It is PRODUCERS

3. Origins And Types of Estuaries
 Estuaries are semi-enclosed areas where
fresh water and seawater meet and mix
 They therefore represent a close
interaction between land and sea
 Estuaries are among the most productive
environments on earth.
 Estuaries also rank among the
environments most affected by humans

4.  Estuaries are scattered along the shores
of all the oceans and vary widely in origin,
type, and size
 They may be called lagoons, sloughs, or
bays
Origins And Types of Estuaries

6. estuaries

7. Physical Characteristics of
Estuaries
 Influenced by the tides and mixing of fresh
and salt water, estuaries have a unique
combination of physical and chemical
characteristics
 These factors govern the lives of the
organisms that live there.

8. Types of Estuarine Communities
 Several distinct communities are
associated with estuaries
 One consists of the plankton, fishes, and
other open water organisms that come in
and leave with the tide
 Several other communities are permanent
parts of the ecosystem

9.  Open Water
 Mudflats
 Salt Marshes
 Mangrove Forests
Types of Estuarine Communities

10.  One of the reasons many of the world’s great
cities developed around estuaries is the rich
supply of fish and shellfish in or near estuaries
 Many species of commercially important fishes
and shrimps use estuaries as nurseries
 90% of the marine commercial catch in the
northern Gulf of Mexico, for example, is of
species that depend on estuaries at some point
in their lives
Types of Estuarine Communities:
Open Water

11.  The bottoms of estuaries that becaome exposed during
low tide often form mudflats
 Organisms exposed to desiccation, wide variations in
temperature, predation, and variations in salinity.
 Bacteria are abundant in mudflats as decomposers of
organic matter.
 Chemosynthetic bacteria (hydrogen sulfide)
 Infauna: Dominant animals in mudflats that burrow
 Epifauna: aniamls that live on the surface or as sessil
forms
 These include detritivores, deposit, suspension, and filter
feeders
Types of Estuarine Communities:
Mudflats

12.  Estuaries in temperate and subtropic
regions are usually bordered by extensive
grassy areas that extend inland from the
mudflats
 Sometimes they are grouped with coastal
environments flooded at high tide and with
freshwater marshes and collectively called
wetlands
Types of Estuarine Communities:
Salt Marshes

13. Salt Marsh
and Mudflat

14. Some
Inhabitants
of mud flats

15.  Mangrove forests (mangals) are not limited to
estuaries, but in some ways they are the tropical
equivalents of salt marshes, though the two
coexist in many places
 Mangroves are flowering land plants adapted to
live in the intertidal
 75% of all sheltered tropical shores were at one
time fringed with mangroves
 Mangrove forests, however, are being rapidly
destroyed by humans
Types of Estuarine Communities:
Mangrove Forests

17. Biotic Components – refer to
organisms that are living or were
once living.
Abiotic components – are the
nonliving and chemical elements in
an ecosystem.

18. The Intertidal Zone
 The intertidal zone is the area located
between high tide and low tide.
 High tide is marked by the strandline, a long line of
seaweed and debris deposited on the beach during
each high tide
 Organisms that live in the intertidal zone are
specifically adapted to meeting the challenges
of living in an area that has alternating periods
of wet and dry, as the tides come in and go out
each day

19. Conditions that characterize an
intertidal zone
Temperature variation
 Exposure waves
High levels of salinity

20.  Adaptations of organisms include ability to
burrow, ability to hide in shell, cling to
surfaces, store water in the body for long
periods of time, excrete excess salt, etc.
 Beach fleas live in the seaweed of the
strandline, in the upper intertidal area
 Crabs can burrow into the sand…snails can
protect themselves from drying out or being
preyed upon by hiding in shells

21. The end