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| Lake
Pontchartrain, at 164,000
hectares, is the largest
oligohaline estuary in
the southeastern
U.S. It is shallow,
less than 15 feet in most
places, and the salinity
is typically 1-7 parts
per thousand (or up to
20% of seawater).
It is enclosed by land
except for two natural
passes and one man-made
canal which connect it to
the Gulf of Mexico.
Lake Pontchartrain is
also geologically young;
just 11,000 years ago the
area was dry. |
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| In
a system as diverse and
temporally unstable as
Lake Pontchartrain it is
a difficult task to
determine the current
health of the system. We
are involved in a two
prong approach to
assessing the biotic
component of the lake's
integrity. Regular,
repeated sampling
throughout the lake is
being undertaken by UNO
faculty and students to
determine the current
status of fish
populations. To better
understand what would
constitute the
"pristine" (or
undisturbed) fauna of the
lake we are also
collecting data on
historical collections
deposited in natural
history museums. |
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| Over
125 species of fish have
been recorded from Lake
Pontchartrain. The fauna
is dominated by sciaenids
in the saltier mid and
eastern regions of the
basin and by centrarchids
where freshwater streams
and swamps drain into the
lake. However, the bay
anchovy, Anchoa
mitchilli is far and
away the most abundant
fish species in the lake. |
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| There
is no "typical year"
for Lake Pontchartrain, or if
there is, it's filled with
untypical events, which make
year-to-year comparisons
difficult. The ecosystem is
significantly impacted by natural
phenomena, such as floods,
periods of low precipitation, and
whatever impacts El Nino(La Nina)
brings to the area. Our attempts
at understanding the basin have
to take this natural variation
into consideration. |
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