Decomposition patterns and nitrogen dynamics of black mangrove (Avicennia germinans)leaf litter in disturbed estuaries linked to the Lower Laguna Madre, Texas
Abstract
Description
Estuaries
are
among
the
most
productive
aquatic
systems
in
the
world
but
are
subject
to
both
anthropogenic
and
natural
disturbances.
With
increasing
environmental
concerns,
efforts
have
become
commonplace
in
assessing
the
status
and
trends
of
environmental
conditions.
In
this
study,
an
assessment
of
ecosystem
status
of
various
estuaries
affected
by
different
disturbances,
was
attempted
through
the
examination
of
key
functional
processes
such
as
leaf
litter
decomposition
and
nutrient
dynamics
during
decay.
Three
estuaries
located
along
the
Brownsville
Ship
Channel
near
the
southern
terminus
of
the
Lower
Laguna
Madre
in
Texas
were
studied.
The
overlying
goal
of
this
study
was
to
compare
the
functional
state
of
these
estuaries,
utilizing
leaf
litter
decomposition
rates
and
nitrogen
dynamics.
Black
mangrove
(Avicennia
germinans)
leaves
were
used
as
the
decomposition
substrate
since
it
is
endogenous
to
the
Lower
Laguna
Madre
system.
Several
aims
were
addressed
in
this
investigation:
1)
determine
decomposition
patterns
(decay
rates,
half-‐lives,
recalcitrant
pool
sizes);
2)
compare
N
content
changes
in
decomposing
mangrove
leaves;
3)
evaluate
N
immobilization/release
during
decay
processes;
and
4)
appraise
the
value
of
decomposition
process
and
N
dynamics
measurements
as
functional
indicators
in
estuaries
linked
to
LLM.
Metrics
derived
from
the
decomposition
process
and
concurrent
N
dynamics
of
leaf
litter
did
discriminate
among
sites
with
different
known
disturbance
histories.
The
ranking
of
the
studied
sites
based
in
decomposition
patterns
did
not
fully
correspond
to
the
ranking
obtained
through
the
variables
of
N
dynamics.
v
While
these
processes
are
linked
by
the
activity
of
the
decomposer
community,
they
should
be
looked
at
separately
to
further
classify
the
stability
and
ecological
status
of
this
type
of
estuarine
systems
in
terms
of
ecosystem
function
PDF; 43 pgs.
PDF; 43 pgs.