Estuaries
Figure 10.22
Figure 12.01
Estuaries Dramatic fluctuations in salinity - Salinity increases with depth
- Salinity decreases upstream
- Salinity varies with tides
Organisms Must Cope with Salinity Changes Most are euryhaline Or have restricted ranges
Organisms Must Cope with Salinity Changes Osmoconformers - Salt concentration varies with salinity
Osmoregulators - Maintain constant salt concentration in their bodies
estuarine “communities” Open Water Mud (or Salt) Flats Salt Marsh Mangroves
Open Water Community Marine plankton comes in and out with tides
Figure 12.09
Mud Flats Where the bottom of estuary becomes exposed at low tide Many infaunal deposit feeders
Figure 12.12
Figure 12.13b
What lives In the Bottom? Benthic Community! Infaunal Organisms Sediment Matters! Can be “muddy” (like the mud flat) or “sandy” (like the sand flat)
(Bottom) “Intertidal” “Intertidal” zones, between high and low tide, are predominantly related to ROCKY bottoms on the NORTH SHORE (LIS)…but are made of either SAND or MUD (i.e. “soft bottom” habitats) in bays/ponds etc.
Figure 11.34
Soft=organisms can burrow
Soft Bottom Intertidal Communities Unstable, sediments move due to currents, waves and tides Can’t hold on - Not many seaweeds
- Animals must burrow = infauna
- Clams use foot
- Crustaceans dig
- Sea cucumbers eat
Figure 11.31a
Figure 11.31b
Figure 11.31c
Figure 11.31d
Figure 11.32
Soft Bottom Intertidal Communities Grain size of sediment is important
What else lives there? SMALL invertebrates Clams Sand Crabs Meiofauna: Tardigrades
“Water Bear” (fnft)
Grain Size of sediment
Grain Size of sediment Determines ability to stay wet - Coarse sediments drain fast
- Fine sediments drain slower
- Mixture – blocks water drainage
Figure 11.28a
Figure 11.28b
Figure 11.28c
Problems of living in sediment - But it is in coarse sediments
Problems of living in sediment - Most infauna are deposit feeders or suspension feeders
- More organic matter (detritus) in fine sediments
Problems of living in sediment Oxygen availability - Used up by animals and bacteria
- Replenished by water flowing though sediment
- Problem in muddy bottoms
Problems of living in sediment
What if?? That “mud/sand” mixture has “GRASS” or vegetation growing in it? Then it gets a different name – a “Salt Marsh” (like Flax Pond)
Salt Marshes Common in temperate regions Extend landward from the mudflats
Salt Marshes Dominated by salt tolerant land grasses - Spartina = cord grass (alterniflora and patens) and other grasses (spike grass, switch grass etc.)
- Bushes/Shrubs = Groundsel bush, Iva
- Some invasives too…
Figure 12.14
Figure 12.07
Local… Now a few slides of your “local” salt marsh, mud flat community and the species that live there…
Figure 12.08
Tropical Version We live in the NE, colder climate, so we have salt marshes… In the South, warmer climates prevail, and they get MANGROVES growing in the same “intertidal zone.”
Mangrove Forests Common in tropical regions Provide a home to many other marine animals
Figure 12.19
“BRIEF WRAP UP” Food “web” and locations Salt Marsh Open Water Mangrove
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