1. JQ: What is an estuary?
The Kalalau Trail – Kauai

2. -Estuaries are highly affect by humans
-Estuaries - partially enclosed, coastal and transition areas where fresh water from rivers mixes with seawater (called brackish)
ESTUARIES
-Estuaries are highly affect by humans
-Productivity and biomass are extremely high
-Primary producers are sea grasses that need good light and low sediment.
NOAA

3. NEW JERSEY ESTUARIES
NOAA

4. 1. Drowned River Valleys or Coastal Plain Estuaries
TYPES OF ESTUARIES
1. Drowned River Valleys or Coastal Plain Estuaries
Formed when sea level rose due to melting ice at the end of the last ice age
Most common type
Examples – Chesapeake Bay, Delaware Bay, Newark Bay
NOAA

5. Examples – Outer Banks, NC, Texas Coast, Long Beach Island, NJ
TYPES OF ESTUARIES
2. Bar-Built Estuary
Form when sediments accumulate along the coast as sand bars and barrier islands that act as a wall between the ocean and fresh water from rivers
Examples – Outer Banks, NC, Texas Coast,
Long Beach Island, NJ
NOAA

6. Formed when land sank or subsided due to movements in the crust
TYPES OF ESTUARIES
3. Tectonic Estuaries
Formed when land sank or subsided due to movements in the crust
Example - San Francisco Bay
NOAA

7. Examples - Norway, Alaska, New Zealand, Puget Sound, WA
TYPES OF ESTUARIES
4. Fjords
Formed when advancing glaciers cut deep valleys along a coast and then the valleys were submerged when sea level rose
Examples - Norway, Alaska, New Zealand, Puget Sound, WA
NOAA

8. JQ: Match the type of estuary to its name or example:
____ Fjord
____ Bar – built
____ Drowned River Valley
____ Tectonic Estuary
Forms when crust shifts/lowers
The result of flooded areas due to melting of ice from ice age
Formed in areas where brackish water is contained inside of a sand bar
Formed from valleys that have been carved by glaciers

9. PHYSICAL CHARACTERISTICS OF ESTUARIES
Salinity – fluctuates from place to place & time to time
- organisms that stay in one place faced with dramatic changes in salinity
Salty seawater is more dense and stays on the bottom
Salt wedge of seawater forms under river runoff when the tide comes in. This layers the salinity.

10. SALT WEDGE – high river flow, low tide - nutrients & sediments from river enter estuary
WELL-MIXED – low river flow, moderate tide – tidal turbulence mixes waters together
PARTIALLY-MIXED – low river flow, moderate tide – similar to well-mixed with deeper channel
FJORD – small surface area, high river flow, little tidal mixing
REVERSE – little river inflow, high evaporation

16. PHYSICAL CHARACTERISTICS OF ESTUARIES
2. Temperature – varies due to shallow depths and large surface areas
– organisms exposed at low tide face even more drastic daily and seasonal temperature changes
3. Turbidity
- large amounts of suspended sediments reduce water clarity
- very little light penetrates water column
- particulate matter clogs filter feeders

17. PHYSICAL CHARACTERISTICS OF ESTUARIES
4. Substrate – type of bottom – mostly sand & soft mud
- rivers carry large amount of sediment, organic matter AND pollutants into estuaries
- infauna have a more stable environment than epifauna because mud traps the salt

18. 5. Oxygen - depletion can occur in the mud or in the water column due to bacterial respiration (ANOXIA)
6. Nutrients - come from river runoff and provides for a detritus-based food chain, inverted energy pyramid increases productivity
7. Water Depth - zones are determined by the tides, shallow water restricts large predators
NOAA
8. Tides and currents - tidal ebb with river runoff cause net flushing. Tides transport larvae and nutrients into the ocean.

19. Types of estuarine communities:
- typically few species, with many individuals
Open Water
- enter and leave with the tide
- vary with currents, salinity & temperature
Murky water may limit primary productivity of phytoplankton in rest of estuary
Fishes & shrimps use as nurseries
- take advantage of abundant food and safety from predators
NOAA

20. 2. Sea Grass Communities -
primarily subtidal zones where sea grasses can stabilize the substrate
NOAA
NOAA
Leaves of grass slow currents, provide a place of attachment to prevent smothering in sediments, for hiding places, and for food
NOAA

21. 3. Mud Flats - or oyster reefs
NOAA
3. Mud Flats - or oyster reefs
- found in lower intertidal and subtidal zones
- bottoms of estuaries exposed at low tide (organisms experience desiccation, wide temperature changes, predation, salinity changes)
- primary producers are diatoms & bacteria

22. MOST IMPORTANT PREDATORS IN MUDFLATS – FISHES and BIRDS
Infauna live on detritus brought in by tides and rivers
Deposit (mud) or suspension feeders (sandy)
Organisms include:
Bivalves
Burrowing shrimps
oxygenate sediment
Fiddler crabs
Predators (snails, worms, crabs)
MOST IMPORTANT PREDATORS IN MUDFLATS – FISHES and BIRDS
Fishes invade at high tide, birds invade at low tide

23. Figure 12.10

24. Wading shore birds most significant predator
Varying lengths of bills may represent specialization in prey
Example of RESOURCE PARTIONING – sharing of a resource by two or more species to avoid competition

25. develop when muddy sediments allowed to accumulate-waves minimal
4. Salt Marshes - also called tidal marshes, wetlands, swamps or mangrove communities
develop when muddy sediments allowed to accumulate-waves minimal
muddy bottom held together by roots
Producers are Spartina (cordgrass) found mostly in intertidal water
Bacteria in the mud decompose dead plant material and contribute a large portion of the detritus in the estuary
Salt excreting leaves provide food and habitat. Air tubes from the leaves to the roots help oxygenate plants living in anaerobic mud.
NOAA

26. JQ: Why are estuaries the site of so much pollution?

27. Estuaries very productive ecosystems – WHY???
1. Nutrients brought in by tides and rivers
2. Nutrients released by nitrogen-fixing organisms
Decomposition of detritus
most animals feed on dead organic matter
more energy from decomposers than from producers
4. Excess detritus exported to the open ocean by
outwelling

28. LIVING IN AN ESTUARY – COPING WITH CHANGING SALINITY (ADAPTATIONS)
Euryhaline – tolerate wide range of salinities (most)
Stenohaline – tolerate narrow range of salinities (few)
- limited to upper or lower ends of estuary
Maintaining salt and water balance is challenging:
- change behavior (hide, close shell, move or swim away)
- develop high salt tolerances (salt-marsh plants), excrete salt, accumulate water
- osmoconformers –salinity of body fluids vary with the water ex. Most marine invertebrates like lobsters, mussels, etc
- osmoregulators – keep salt concentration of body fluids constant – ex. Most fish (like salmon)

29. LIVING IN AN ESTUARY – ADAPTING TO THE MUD
Disadvantages
- nothing to hold onto
- low oxygen caused by decay of organic mater in mud
Advantage
- salinity fluctuations less drastic
Difficult to move through mud –
- Organisms stay put or move slowly
- Clams use siphons
Low oxygen
- some burrowers pump oxygen-rich water into burrow
- some have hemoglobin – high affinity for oxygen
- some can survive for days without oxygen

30. Estuaries are usually the first dumping site for pollution and have been severely damaged by dredge and fill operations.
Estuaries are important because they support a large commercial seafood industry, prevent coastal erosion, provide recreation .
AND
Estuaries are the sea’s nursery.

31. Chesapeake Bay Video