Disclaimer:
These notes are my personal notes. The course instructor or TAs have
no responsibility for the contents or any discrepancies between the materials
presented in the classroom and these notes. You cannot use or refer to these
notes to support or defend your answers on your exams. I suggest you use these
notes to complement your own notes, and not to solely rely on.
I would appreciate your feedback on any part of these notes that I
may be misunderstanding.
Ø Reading for estuarine ecosystems
sessions: Estuarine Ecology (Day, Hall, et al. 1989) Chapter 1 & 2, plus
any other THREE chapters of your choice from the same book.
Ø Thursday lecture will be taught by
Siripun Taweesuk, PhD student with Dr. Hall, about Tropical Rain Forest in
Thailand and her modeling work.
1.
Estuarine ecosystem (…continued)
What is an
estuary? – where the river meets the sea.
What’s special
about estuarine environment?
If you are
taking a trip in North River, what’s surprising about how the tide works?
-
How far the
tide goes into the land
What does the
tide do? – Swab of water moving up with the tide and then come back down.
How can we tell
in an estuary it’s happening?
How do you tell
how much of water is from the ocean and how much is fresh water? – Using
refractometer.
The most
important thing about estuaries is salt. Salt tells you what’s going on.
Ocean = 5 ppt or 5 % salinity.
According to
Chapter 2 of Day, Hall, et al., what mistake are we making when we use the word
“estuaries”? - There are different
types.
Ø The estuary types are defined by the
relative importance of sea and river.
Ø Gradient of river mouth type – river
dominated delta è ocean
dominated lagoon.
§
North
River: mouth of river at low tide, where tidal bole, the slug of water, goes
up. Tidal flooding, clamshell, barrier
sand island with Spartina grass – normal features of an estuarine
environment in this vicinity of these latitudes.
§
Rocky (wave
cap) headland, Sweden: Water is rising against the land, which is happening all
around the world. Continues with climate warming 1 inch in 10 years. Ocean will
go into land areas, and we might lose 45% of nation’s wetland and marsh birds.
Wetland ea level rising is so fast that the land doesn’t have chance to rebuild
marshes.
§
Nova
Scotia: estuaries are always changing, the fauna/flora are exposed to
tremendous changes. The stressful environ. is not one that is hot or cold, but
change from hot to cold. The organisms in these environments do not have
possibility of being adapted to particular environment, they have to be adapted
to wide range of gradient conditions.
What would you
supposed to be the biodiversity in the estuarine environment? – low. Why?
Why not all
organisms are adapted to wide range of conditions – the cost of adaptation, for
example, energy to make enzymes to work at different temperatures, is too high.
So most of organisms operated in a relatively small range of conditions.
Diversity of
estuaries is low. What about productivity of estuaries?
- high in
detritus.
Water gets mixed
a lot. Whereas in blue water ecosystems where water stratifies and rarely
mixes, thus nutrients fall out. In blue water ecosystems, anything that sinks
doesn’t get mixed back up (except in arctic/antarctic and boreal region).
Estuaries are
shallow. Nutrients don’t fall far down, but mixed up è nutrients are cycled.
Estuaries are
relatively nutrient rich. Plants grow well, and feed the food chain è high productivity.
So why highly
productive environments have low diversity?
èBecause
of the tremendous changes, such as salinity, temperature, pH, or oxygen, few
organisms have invested energy, over evolutionary time, in the wide range of
requirements such as enzymes to live in this wide range of environmental
conditions. è Thus
those organisms that focused on an estuarine environment had little
competition.
§
North
River: typical drowned river mouth estuary. V-shaped river valley where N.
River carried glacial melt water to the ocean 10,000 years ago. Ocean was much
close to Europe than now. Off the Hudson River is Hudson River Canyon. During
Ice age, snowmelt water was locked up in the glaciers. Ocean was 500 km SE of
NYC. Hudson River got to the edge of continental shelf and curved a bid canyon.
Ocean has been rising relative to the land. As it has done that, it created a
favorable sediments fall, fill up the area, grass rolled in this brackish water
environment.
§
Drainage
remnants in N. River estuary: straight lines on the land. In 1930s drained the
marsh to remove mosquitoes. Ended up making favorable environment for another
mosquito of harder bite.
Meandering
– usually happens in flat. River has gone over time back and forth filling in
the flood plain and with Spartina grass.
§
Route 3,
Massachusetts (taken 25 years ago). Looking toward sea. People drove by from
Boston to Cape Cod. Covered with nice forests.
§
Mouth of N.
River: Some features we read about in Chpt. 2. Sand bar where river and ocean
are fighting each other. Drainage ditches, salt marshes, clam/mussel beds.
Clams and filter
feeders are OK now. The concern is fecal coliform from sewage water. But clams
can clean themselves. If we put the clams form polluted water in clean ocean
water, they clean themselves and we can sell them.
§
Flax pond,
a lagoon estuary: Flax pond is a kettle lake. Big piece of glacial ice left and
as it melt piled up all the sand, created sand-built islands. A cut through the
sandbar to the ocean made artificially in 1780 or so and maintained by tidal
action. We can call this salt pond environment because fresh water input is
small. Has same salinity as long island. It’s another type of coastal
environment with lots of Spartina behind barrier beach with relatively
small connection to the ocean.
§
Interior of
the Flax pond: relatively low tide. Mud flats. Spartina. Most productive
amount of OM generated /yr/m2 amongst the highest in the world.
§
Vegetation gradient
diagram: Vegetation is zoned. Near the water: high Spartina (Spartina
alterniflora), back farther; low Spartina alterniflora, Spartina
patens; back farther, different kind of Spartina; upland vegetation,
ibex(?) and cedars.
Zonation
has to do with salt. Salty soil is back farther from the water. Salinity is
always 24 ppt. Why saltiest soil could be farther from salty water? - water leaves paddles and leaves salt as it
evaporates.
§
Transect of
vegetation gradient: at the edge of water, high Spartina, peat muck,
exceptionally high tide zone. Why Spartina higher than it is farther inland? –
When tide goes down, edge area drains. Soil gets oxygen and allows the roots to
pick up more nutrients.
§
Spartina
alterniflora: Spartina
is a flowering plant. And yet, it reproduces rhizominously. Why does Spartina
invest so much energy producing flowers when it can reproduce by roots? –
The sea is moving in and out of the land. Spartina has to keep
colonizing new land.
§
There are
three primary producers (in this Flax pond environment): phytoplankton, macro
algae, and Spartina grass. In addition, there are
single cell plants that live in the surface of the mud that moves in and out as
the tide moves.
§
Dead and new growth of Spartina: May in Flax
pond. Spartina is good detritus. Good food and partly responsible for the
richness of estuarine environment.
§
A graph from de la Cruz’s original paper: Spartina protein
content increases from 10 to 25% as it is decomposed. N-fixing bacteria use
carbon from detritus to fix N. Other organisms, such as shrimps or fish, digest
N and bacteria-rich particles, poop out particles. And bacteria recolonize this
N-diminished particle again to fix N. This is the process that enhances the
quality of food of animals because of this N enhancing detrital food chain.
§
New Jersey marsh aerial picture of drainages.
§
Same New Jersey aerial picture taken with chlorophyll-sensitive film.
High chlorophyll in marsh and along drainages. è Importance of
water drainages, maintaining high prod. At the edges of water channel.
§
Delaware River system and Chesapeake Bay system GIS map: water source
map. Two rivers start in the
same area. However, Chesapeake Bay is the most productive system in the world.
Why? – nutrient input from agriculture (chicken farms and corn fields) and
sewage runoff. Single source to Maryland economy. But…è O2 depletion at the bottom
causing mysterious die-off of aquatic organisms.
§
Same area,
productivity GIS map.
Last modified:
March 24, 2001 (typos corrected on April 21)
Any comments?
E-mail to akogwa@syr.edu