Hypoxia
is
observed
and
projected
to
expand
in
many
aquatic
environments,
largely
due
excess
anthropogenic
nutrient
inputs
climate
change,
thus
influencing
biogeochemical
processes.
Denitrification,
generally
an
anaerobic
process,
removes
bioavailable
nitrogen
produces
nitrous
oxide
(N2O).
However,
limited
observations
of
the
effect
oxygen
on
denitrification
restrict
our
ability
estimate
changes
amount
N2O
emissions
under
perturbations
change.
Here,
we
show
that
all
steps
increased,
while
production
yield
from
decreased
with
decreasing
Chesapeake
Bay
-
largest
estuary
United
States.
The
different
responded
similarly
Bay,
unlike
open
ocean
minimum
zones,
implications
for
accumulation
or
depletion
intermediates
such
as
nitrite
N2O.
Our
also
suggest
current
model
parametrizations
likely
overestimate
removal
presence
oxygen,
which
would
bias
evaluation
cycling,
ecosystem
productivity,
extent
hypoxia.
Overall,
newly
derived
sensitivities
could
be
used
improve
constrain
budget
estuarine
coastal
environments
experiencing
Nature Communications,
Journal Year:
2023,
Volume and Issue:
14(1)
Published: Dec. 13, 2023
The
heavily
human-perturbed
coastal
oceans
are
hotspots
of
nitrous
oxide
(N2O)
emission
to
the
atmosphere.
processes
underpinning
N2O
flux,
however,
remain
poorly
understood,
leading
large
uncertainties
in
assessing
global
budgets.
Using
a
suite
nitrogen
isotope
labeling
experiments,
we
show
that
multiple
contribute
production
throughout
estuarine-coastal
gradient,
sustaining
intensive
flux
Unexpectedly,
denitrification,
rather
than
ammonia
oxidation
as
previously
assumed,
constitutes
major
source
well-oxygenated
waters.
Size-fractionated
manipulation
experiments
with
gene
analysis
further
reveal
niche
partitioning
oxidizers
and
denitrifiers
across
particle
size
spectrum;
denitrification
dominated
on
particles
small
particles.
Total
rate
increases
substrate
concentrations,
suggesting
crucial
interplay
between
nutrients
controlling
production.
factors
identified
here
may
help
understand
climate
feedback
mechanisms
human
activity
oceans.
Sustainability,
Journal Year:
2024,
Volume and Issue:
16(12), P. 5146 - 5146
Published: June 17, 2024
Eutrophication,
driven
by
excessive
nutrient
enrichment
from
sources
like
agricultural
runoff,
industrial
discharge,
and
urbanisation,
has
severely
impacted
the
Black
Sea
since
1980s.
This
study
aimed
to
assess
eutrophication
dynamics
in
Romanian
Exclusive
Economic
Zone
2020
2022
using
Eutrophication
Assessment
Tool
(BEAST),
an
integrated
approach
causes
effects
of
eutrophication.
Data
were
collected
68
stations
during
five
oceanographic
expeditions,
analysing
617
water
samples
for
nutrients,
chlorophyll
a,
zooplankton
species
Noctiluca
scintillans,
dissolved
oxygen.
Additionally,
179
zoobenthic
251
phytobenthic
community
collected.
The
results
indicate
that
coastal
waters
exhibit
higher
levels
algal
blooms
compared
offshore
waters,
necessitating
significant
reductions
concentrations
achieve
good
environmental
status.
In
transitional
within
Danube
Delta
Biosphere
Reserve,
a
55%
reduction
inorganic
phosphorus
43%
nitrogen
are
required,
while
need
38%
37%,
respectively.
highlights
improved
wastewater
treatment,
stricter
runoff
controls,
continuous
monitoring.
Effective
ecosystem-based
management
strategies,
zone
management,
international
cooperation
essential
mitigate
promote
long-term
health
ecosystem.
Journal of Marine Science and Engineering,
Journal Year:
2025,
Volume and Issue:
13(2), P. 343 - 343
Published: Feb. 13, 2025
Global
fisheries’
production
has
intensified
rapidly
over
recent
decades,
making
significant
contributions
to
food
security
and
economic
development.
However,
this
growth
exerted
pressure
on
marine
ecosystems
altered
coastal
nitrogen
cycling.
This
study
focused
Sansha
Bay,
an
important
aquaculture
harbor
in
SE
China,
with
measurements
of
environmental
parameters
nitrate
N–O
isotopic
compositions,
explore
the
impact
distinct
mariculture
types
cycling
a
farming
bay.
The
mean
concentration
was
120.7
±
24.2
μmol
dm−3,
N/P
ratio
69.6
19.6,
indicating
that
water
column
is
state
eutrophication.
Different
practices
influence
nutrient
status
water,
mixed
(shellfish,
seaweed,
fish)
increasing
concentrations
reducing
ratios,
while
seaweed
reduces
increases
ratios.
In
spring,
average
δ15N
δ18O
values
were
8.4‰
8.7‰,
respectively,
compared
9.8‰
4‰
recorded
previously
winter.
Such
variation
may
be
attributed
greater
spring
when
driven
mainly
by
assimilation.
terms
type,
assimilation
stronger
zones,
nitrification
more
pronounced
zones.
Overall,
results
demonstrate
different
Bay
body,
seaweed-based
systems
contributing
sustainable
development
effectively
mitigating
Frontiers in Marine Science,
Journal Year:
2023,
Volume and Issue:
10
Published: April 11, 2023
Although
great
efforts
have
been
made
to
decrease
nutrient
(notably
nitrogen
and
phosphorus)
loads
lighten
related
environmental
damages,
coastal
eutrophication
remains
a
persistent
crisis.
To
estimate
whether
the
rapid
development
of
local
economy
has
accelerated
in
Zhanjiang
Bay,
newly
developing
industry
South
China,
combination
seasonal
nutrients
other
physicochemical
parameters
from
twenty
cruises
during
2017-2021
historical
data
(past
30
years)
was
analyzed
this
study.
The
results
showed
that
upper
bay
is
significantly
higher
than
lower
(more
8
times),
which
mainly
terrestrial
input
weak
hydrological
conditions
bay.
Also,
more
severe
rainy
seasons
dry
(nearly
2
times)
because
abundant
phosphorus
were
brought
into
by
discharge
river
water.
From
long-term
perspective,
dissolved
inorganic
concentrations
effectively
controlled
while
phosphate
concentration
increased
sharply
past
years.
Correspondingly,
Bay
over
years,
index
recent
5
years
(2017-2021)
nearly
10
times
1990s,
suggesting
increase
increasing
industrial
factories
around
rather
culprit
causing
aggravation
eutrophication.
Our
study
essential
implement
land-ocean
integrated
control
strategy
improve
water
quality
mitigate
Abstract
Few
coastal
ecosystems
remain
untouched
by
direct
human
activities,
and
none
are
unimpacted
anthropogenic
climate
change.
These
drivers
interact
with
exacerbate
each
other
in
complex
ways,
yielding
a
mosaic
of
ecological
consequences
that
range
from
adaptive
responses,
such
as
geographic
shifts
changes
phenology,
to
severe
impacts,
mass
mortalities,
regime
loss
biodiversity.
Identifying
the
role
change
these
phenomena
requires
corroborating
evidence
multiple
lines
evidence,
including
laboratory
experiments,
field
observations,
numerical
models
palaeorecords.
Yet
few
studies
can
confidently
quantify
magnitude
effect
attributable
solely
change,
because
seldom
acts
alone
ecosystems.
Projections
future
risk
further
complicated
scenario
uncertainty
–
is,
our
lack
knowledge
about
degree
which
humanity
will
mitigate
greenhouse-gas
emissions,
or
make
ways
we
impact
Irrespective,
ocean
warming
would
be
impossible
reverse
before
end
century,
sea
levels
likely
continue
rise
for
centuries
elevated
millennia.
Therefore,
risks
projected
mirror
impacts
already
observed,
severity
escalating
cumulative
emissions.
Promising
avenues
progress
beyond
qualitative
assessments
include
collaborative
modelling
initiatives,
model
intercomparison
projects,
use
broader
systems.
But
reduce
rapidly
reducing
emissions
greenhouse
gases,
restoring
damaged
habitats,
regulating
non-climate
stressors
using
climate-smart
conservation
actions,
implementing
inclusive
coastal-zone
management
approaches,
especially
those
involving
nature-based
solutions.
