Transcript coastal plain estuaries. Others are known as

Estuaries
Introduction
• We’ve already seen what it’s like near the edge!
• Ocean life is rough. Adaptation is the key to long term
survival.
• What about in environements which appear to be less
disturbed? Does chaos still rule in a world of “living
on the edge,” such as estuaries?
• Let’s find ouch, shall we?
Estuaries
• Estuaries are old structures.
• Invading seas to land masses form drowned river
valleys or coastal plain estuaries.
• Others are known as bar-built estuaries, where
sediment accumulation restricts sea/fresh water
interaction.
• Glaciers can also create estuaries by cutting off sea
water access to inland lakes (fjords).
Salty sources: Cape Hatteras is a perfect example of a
man-made estuary. (High exchange, high productivity)
Milford Sound, NZ. Little exchange (low D.O.)
Good example of a fjord system.
Salt wedges
Tidal Action:
Animals in some
estuaries are subjected
to two cycles of
varying salinity.
Animals in these
harsh environments
enjoy benefits of
highly productive
grounds at the expense of
difficult living conditions.
How well do you tolerate change?
Some animals are just better than others…
Plants play an important
role in estuary “stability.”
Cordgrass (Spartina)
is an example of a grass
which promotes bank
stability while providing
shelter for many small
animals.
Like mangroves, they excrete
excess salt from their blades.
Other plants store water in succulent “leaves.”
This form of water storage dilutes salts taken up
by the plant during photosynthesis.
Mudflats and marsh creeks serve as spawning
grounds for many species of fish.
Catadromous: Sea to fresh
Anadromous: Fresh to sea
Primary productivity:
very high in esturary mud
flats.
Especially for these
horn snails
Cerithidea californica
which are excellent
deposit feeders.
And the list goes on…
Birds have also evolved to take advantage of
abundant food sources on mudflats.
Feast or famine?
When the tide is in…
food is scarce.
When the tide drops…
animals feast while they
can…
Biofiltration: Estuary’s most important role?
This salt marsh is dominated by grasses and benthic bacteria.
Figure 12.18
Figure 12.19
Figure 12.20
Figure 12.21
Figure 12.22