Benthic
foraminiferal
assemblages
of
Balayan
Bay,
Calaca,
Batangas
Diana M.
Lopez*
and
Maybellyn
A.
Zepeda*+
*School
of Earth
and
Materials
Science
and
Engineering,
Mapúa
Institute
of
Technology,
Intramuros,
Manila
+Petrolab
Paleontology
Unit,
Lands
Geological
Survey
Division,
Mines &
Geosciences
Bureau,
North
Ave.,
Diliman,
Quezon
City
Abstract
This
study
presents
the
microfauna
found in
Balayan
Bay,
Calaca,
Batangas.
Balayan
Bay is a
part of
the
primary
bay
system
on
Batangas
Gulf
Coast.
It is an
open bay
facing
the
South
China
Sea. It
is also
located
near a
coal-fired
thermal
power
plant
and
serves
as
recipient
of
domestic
and
industrial
waste.
The
Balayan
Bay–Calaca
area has
been the
subject
of
several
studies
in
recent
years.
Among
the
studies
conducted
focused
on the
sedimentology,
geochemistry
and
geotechnical
investigation
of the
area.
A total
of
twenty
samples
were
collected
within
10m
lateral
intervals
between
sampling
points
from the
sea-surface
sediments
of the
bay.
These
were
analyzed
for
their
microfaunal
content.
Microfauna
identified
in the
samples
consist
mostly
of
Foraminifera,
which
are
single-celled
animals
belonging
to
Protozoa,
most of
which
are
marine
although
few have
been
reported
from
fresh
water.
Few
mollusks,
numerous
coral
fragments
and
other
unidentifiable
organic
forms
are also
present.
Results
of this
study
showed
that
sampling
points
(SP)
1-10
exhibited
lower
foraminiferal
abundance
and
diversity
while
sampling
points
(SP)
11-20
displayed
higher
foraminiferal
content
as well
as
higher
species
diversity
(simple
and
Shannon-Weaver).
SP 1-10
consists
of only
few
foraminifera,
with the
majority
identified
as
Quinqueloculina
seminulum
(Linnaeus)
and
Ammonia
beccarii
(Linné).
The
faunas
identified
in SP
11-20
consist
of
abundant
planktonic
foraminiferal
assemblage
such as
Globigerina
bulloides
(d’Orbigny),
Orbulina
universa
(d’Orbigny)
and
Globigerinoides
trilobus
(Cushman)
and
benthonic
assemblage
of
Nonion
scaphum
(Montfort),
Elphidiononion
poeyanum
(d’Orbigny),
Bulimina
gibba
(Cushman),
Elphidium
lessonii
(Montfort)
and
Lenticulina
convergens
(Linnaeus).
The most
dominant
benthonic
species
include
Quinqueloculina
seminulum
(Linnaeus)
and
Ammonia
beccarii
(Linné).
Variations
in
abundance
and
diversity
of the
species
could
probably
be the
result
of
factors
such as
high
influx
of
sediments
and
nutrients
in
the area
as well
as to
other
anthropogenic
causes
due to
disposal
of
domestic
and
municipal
wastes
in the
bay. In
cases,
where
all
samples
were
collected
at
depths
not
greater
than
five
meters,
foraminiferal
occurrence
is most
likely
determined
by
differences
in
environmental
conditions
and type
of
substrate.