Journal of Oceanography, Vol. 56, pp. 69 to 78. 2000
Influences of Nutrient Outwelling from the Mangrove
Swamp on the Distribution of Phytoplankton in the
Matang Mangrove Estuary, Malaysia
KATSUHISA T ANAKA1 and POH-SZE CHOO2
1
National Research Institute of Fisheries Science,
2-12-4, Fukuura, Kanazawa-ku, Yokohama 236-8648, Japan
2
Fisheries Research Institute, Department of Fisheries, 11960 Batu Maung, Penang, Malaysia
(Received 16 October 1998; in revised form 10 March 1999; accepted 1 May 1999)
Distributions of dissolved nutrients and Chl. a were investigated in the Sangga Besar
River Estuary in the well-managed Matang Mangrove Forest in West Malaysia. In
the estuary, spring tide concentrations of ammonium, silicate and phosphate were
higher than those in the neap tide, which suggests that these nutrients are flushed
from the mangrove area by the inundation and tidal mixing of the spring tide. Ammonium comprised over 50% of the dissolved inorganic nitrogen in the spring tide,
while nitrite tended to dominate in the neap tide, indicating the predominance of
nitrification inside the estuary in neap tides. Nutrient concentrations in the creek
water were higher than those of estuarine water, indicating the nutrient outwelling
from the mangrove swamp and ammonium regeneration from mangrove litter in the
creek sediments. The maximum concentration of Chl. a in spring tides reached 80
µg/l while it was below 20 µg/l in the neap tides. These variations in the phytoplankton
biomass and nutrients probably reflect the greater nutrient availability in the spring
tide due to outwelling from the mangrove swamp and creek.
1. Introduction
Little information is available on the distribution and
dynamics of dissolved nutrients in tropical mangrove areas. Detailed studies on nutrient dynamics in tropical
coastal areas are limited to coral reef areas (Boto and
Wellington, 1988; Alongi et al., 1992) or pelagic shelf
waters (Robertson et al., 1998). Two investigations which
examined nutrients in Malaysian mangrove estuaries using mixing diagrams have been made (Nixon et al., 1984;
Wong, 1984). Such studies have provided information on
nutrient concentrations and their relationships with salinity. However, the distribution and behavior of nutrients are usually affected by tidal and weather conditions.
Uncles et al. (1990) showed pronounced spring-neap variability in currents and salinity stratification in the Merbok
River Estuary in Peninsular Malaysia. In the riverine forest type mangrove, the mangrove swamp is inundated by
river runoff in the wet season and traps land-derived material, which is later outwelled by the tidal mixing and
Keywords:
⋅ Mangrove estuary,
⋅ nutrient
outwelling,
⋅ creek,
⋅ phytoplankton
distribution,
⋅ chlorophyll a.
transportation during inundation. Thong et al. (1993) demonstrated that inorganic nitrogen increased after heavy
rains or when tides inundated the forest floor in a mangrove creek in Peninsular Malaysia. Therefore, the nutrient mixing diagrams may give different results between
spring and neap tides, and between the wet and dry seasons, which will effect the phytoplankton biomass in the
estuary.
The major objectives of this study are to investigate
tidal effects on the outwelling of inorganic nutrients in
the wet season in the Sangga Besar River Estuary in the
well-maintained Matang Mangrove Reserve, and to examine their relationships to the phytoplankton distribution in the estuary.
2. Materials and Methods
Matang Mangrove Forest Reserve in Perak is reputed
to be the world’s best managed mangrove forest. The
Reserve, situated on the northwestern coast of Peninsular Malaysia, consists of some 40,000 hectares of mainly
Rhizophora apiculata mangroves (Khoo, 1989). It is the
largest tract of mangrove forest in Peninsular Malaysia
and has been under sustainable management since the
early part of the 20th century.
Corresponding author e-mail: [email protected]
Copyright © The Oceanographic Society of Japan.
69
Table 1. Tidal data for the sampling times.
Year
1996
Date
Tidal range (m)
Spring (S) or Neap(N)
Ebb (E) or Flood (F)
Sampling stations
Oct. 29
2.5
S
E
R1–R7
Nov. 5
0.4
N
F
R1–R6
1997
Oct. 31
2.4
S
E
R1–R5
Nov. 8
1.1
N
F
R1–R6
Nov. 11
1.4
N
F
C1–C5
Nov. 22–23
1.3
N
E, F
R2–R6
Dec. 1–2
2.5
S
E, F
R2–R6
*Tidal data at Lumut (40 km south of Sangga Besar River Estuary) were obtained from the tide table published by the Royal
Malaysian Navy.
Fig. 2. Heights of high and low waters at Lumut (40 km south
of Sangga Besar River Estuary) during the period from 27
Oct. to 6 Nov., 1996 (data from the tide table published by
the Royal Malaysian Navy).
Fig. 1. Maps of the Matang Mangrove Forest and Sangga Besar
River Estuary with the location of sampling stations.
70
K. Tanaka and P.-S. Choo
Sampling was conducted from October to December
in 1996 and 1997 in the wet season within two days before or after, spring or neap tide. Sampling locations in
the Sangga Besar River Estuary in the Matang Mangrove
Forest and details of tidal data at the sampling times are
shown in Fig. 1 and Table 1, respectively. Tides in Kuala
Sepatang (Fig. 1) are typically semi-diurnal with Mean
High Water Springs of 2.65 m (Sasekumar et al., 1994).
Figure 2 shows heights of high and low waters at Lumut
(40 km south of Sangga Besar River Estuary) during the
period from 27 Oct. to 6 Nov., 1996 (data from the tide
table published by the Royal Malaysian Navy). Observations of time series of sea level at Stn. R3 in the periods
of 22–23 Nov., 1997 (neap) and 1–2 Dec., 1997 (spring)
were made by a self-recording tide gage (RIGO RMD5225). The differences in the tidal range and high/low
water time between from the tide table at Lumut and from
the observations were within 20 cm and 90 min., respectively. The Matang Mangrove Forest is a Riverine Forest
Type mangrove (Wolanski et al., 1992), which are inundated by most spring high tides. During a neap tide, almost all water is confined to the main channel. In con-
trast, the vegetated mangrove area becomes flooded during a spring tide. The annual mean rainfall for the town
of Taiping (10 km east of Kuala Sepatang: Fig. 1) is 3990
mm, and October and November are normally the wettest months of the year with heavy rainfall (Sasekumar et
al., 1994). The river basin is deepest between Stn. R4
and Stn. R5 (4–6 m) and is connected to the mudflat area
by a shallow sill region at the river mouth (1.5–2.5 m).
Similarly, the bottom of the deeply scoured creek is over
10 m immediately adjacent to the river basin (Stn. C1).
In 1996 (29 Oct. and 5 Nov.), the nutrients distributions in the estuary was compared between spring and
neap tide conditions. To evaluate the effect of inundation
over the mangrove forest floor in spring tide on the distribution of nutrients in the estuary, the spring tide observation (29 Oct.) was made in the low water period. In
1997, comparisons of nutrients, chlorophyll a (Chl. a)
and dissolved oxygen concentrations between the estuary and creek was made on 8 Nov. (estuary) and on 11
Nov. (creek) during the neap tide condition. Chl. a concentrations in the estuary were monitored from 31 Oct.,
1997 to 2 Dec., 1997 (4 times) to compare the
phytoplankton biomass between spring and neap tide.
Salinity, temperature and turbidity were measured
with a T-S meter (ALEC ACT20-D) and a light scattering type turbidimeter (ANALITE 152) at 1 m depth intervals in the water column meter. Measured turbidity in
NTU (Nephelometric Turbidity Unit) and the concentration of suspended solids (SS: mg/l) were linearly related
(NTU = 1.16 × SS – 8.94, r = 0.989). Dissolved oxygen
(DO: mg/l) was measured by a TOA model-WQC-20A
water quality checker.
Water samples were taken using a 1.5 l water sampler (Wildco-1520) at several depths (surface, mid-depth
and near-bottom) within 2 hours of slack tide to minimize strong current effects. Samples were immediately
filtered (0.45 µm Millipore HA or Wattman GF/C) into
acid washed polypropylene bottles. They were cooled on
ice on the boat and stored in a refrigerator until laboratory analyses, which were completed within 24 hrs for
ammonium [NH4 -N], and within 72 hrs for nitrate [NO3 N], nitrite [NO2 -N], silicate [Si(OH)4-Si] and phosphate
[PO4-P]. NH 4-N was measured by the modified indophenol method (Sasaki and Sawada, 1980). Nitrate, nitrite,
phosphate, silicate and Chl. a were analyzed by standard
methods (Parsons et al., 1984) using a spectrophotometer (SHIMADZU UV-1601). Water samples for the microscopic observation of phytoplankton were taken on 8
and 11 Nov., 1997 and were fixed with Lugol’s solution.
Sediments were taken by a Birge-Ekman grab sampler at each station on 24 Dec., 1997. Sub-samples (0–1
cm) of surface sediments were taken through the flaps at
the top of the sampler for organic carbon (Org-C) and
total nitrogen (Total-N) analysis. Redox condition of sur-
face sediments (0–1 cm) was measured by a platinum electrode (Hach Model 44480). The sediment samples for OrgC and Total-N were dried and gently crushed using a pestle and mortar and analyzed with an elemental analyzer
(FISONS EA1108).
3. Results
3.1 Dissolved nutrient distributions in spring and neap
tides
Sections of salinity and nutrient concentrations in
the spring (29 Oct., 1996) and neap tide (5 Nov., 1996)
are shown in Figs. 3 and 4, respectively. The rage of water temperature in Sangga Besar River Estuary during the
observations is 27.1–31.9°C (average 30.17°C), in which
the surface water temperature is most variable according
to the daily irradiance changes. In the spring tide (Fig.
3), the water was vertically well-mixed and turbidity
ranged from 20–840 NTU. The highest turbidity value
(840 NTU) was observed in the bottom layer of the mud
flat area (Stn. R1) which suggests the resuspension of mud
flat sediments. Ammonium-N and silicate-Si showed
higher concentrations between Stn. R3 and R5 with maximum at Stn. R4, while higher phosphate-P concentrations
were observed between Stn. R2 and R4 with maximum at
Stn. R2. Nitrite-N concentrations were lower in the upper part of the estuary (below 1 µM) and increased with
salinity showing the higher concentrations in the mud flat
area, while nitrate-N showed the minimum concentration
at Stn. R3 and increased with salinity over 20 psu. Ammonium-N was predominant in the dissolved inorganic
nitrogen (DIN) throughout the estuary in the spring tide
(over 50%).
In the neap tide (Fig. 4), the water in the upper estuary (Stn. R4–R6) was highly stratified with salinity over
25 psu in the bottom layers of Stn. R4–R5. The presence
of such highly saline bottom water in the upper part of
the estuary implies the reduced mixing by the stratification in the inner sill region in the neap tide. During the
neap tide, turbidity was much lower than that of the spring
tide (4–24 NTU). Phosphate-P and nitrite-N concentrations were higher in the bottom layers of Stn. R5–R6,
while ammonium-N, nitrate-N and silicate-Si concentrations increased with decreasing salinity, showing the fresh
water source of these nutrients. Phosphate-P and nitriteN concentrations in the highly saline bottom water (Stn.
R4–R6) were higher than those of high salinity water of
mud flat area (Stn. R1–R2), which also indicates the limited mixing between these two waters during the neap
tide. In the neap tide, DIN in the bottom layers of Stn.
R5–R6 was predominated by nitrite-N.
In the spring tide, ammonium-N and silicate-Si and
phosphate-P showed higher concentrations between Stn.
R2 to R4, and the concentrations were much higher than
Influences of Nutrient Outwelling from the Mangrove Swamp on the Distribution of Phytoplankton
71
those in the neap tide, which suggests that these nutrients
are flushed from the mangrove area by the inundation and
tidal mixing of the spring tide.
3.2 Comparison of nutrient concentrations between the
estuary and creek in the neap tide
Sections of salinity, DO, Chl. a and nutrient concentrations in the estuary (8 Nov., 1997) and creek (11 Nov.,
1997) are shown in Figs. 5 and 6, respectively. In the estuary (Fig. 5), the water in the upper estuary (Stn. R4–
R6) was stratified as in the case of 1996 (Fig. 4), although
the salinity in the bottom layers of Stn. R4–R5 was slightly
lower (over 20 psu). Dissolved oxygen (DO) concentrations showed the maximum at Stn. R2 which coincided
with a Chl. a maximum, showing the DO generation by
the phytoplankton. DO concentrations were lower in the
low salinity surface water of Stn. R4–R6, consequently
DO concentrations were higher below the salinity gradient at the bottom water of Stn. R4–R6. However, a DO
minimum (below 4 mg/l) was observed at the bottom
Fig. 3. Salinity, turbidity and nutrients sections in the Sangga Besar River Estuary for the spring tide (29/10/96).
72
K. Tanaka and P.-S. Choo
water of Stn. R3 which coincided with phosphate-P maximum (over 0.6 µM). Phosphate-P was lowest at the bottom layer of Stn. R2, showing the result of consumption
by the phytoplankton. As in the case of 1996 (Fig. 4),
ammonium-N, nitrate-N and silicate-Si concentrations
increased with decreasing salinity, showing the fresh
water source of these nutrients. However, nitrite-N concentrations showed the maximum (over 6 µM) in the intermediate salinity zone (Sal. 15–20 psu) above the sa-
line bottom water (Stn. R3–R6).
In the creek water (Fig. 6), the salinity range is relatively small compared to the estuarine water, with the
maximum at the bottom layer of creek outlet (over 21
psu) which decreased to below 18 psu at the upper reach
of the creek (Stn. C5). DO concentrations showed the
maximum at Stn. C2 which coincided with high concentrations of Chl. a showing the active DO generation by
the phytoplankton. DO concentrations decreased below
Fig. 4. Salinity, turbidity and nutrients sections in the Sangga Besar River Estuary for the neap tide (5/11/96).
Influences of Nutrient Outwelling from the Mangrove Swamp on the Distribution of Phytoplankton
73
Fig. 5. Salinity, DO, Chl. a and nutrients sections in the Sangga Besar River Estuary for the neap tide (8/11/97).
2 mg/l at the upper reach of the creek (Stn. C5). Chl. a
concentrations were over 30 µg/l at the surface water of
lower part of the creek (Stn. C1–C2), which is much
higher than the estuarine water (Fig. 5).
Concentrations of phosphate-P and silicate-Si were
much higher in the upper reach of the creek which gradually decreased in the lower part of the creek indicating
that phosphate-P and silicate-Si is outwelled from the
mangrove swamp. Ammonium-N concentrations were
highest in the deeper area of the lower creek, which suggests regeneration of ammonium from the bottom
sediments. In fact, Org-C contents in the surface sediments
of the creek were higher than those of the river sediments,
74
K. Tanaka and P.-S. Choo
and surface sediments at Stn. C1 and C2 contained large
amounts of part-decomposed mangrove litter. The higher
Org-C contents and C/N ratios in the surface sediments
of deeper Stn. C2 and C3 indicate the accumulation of
mangrove litter (Table 2). Moreover, redox condition (Eh)
was lower than –200 mV at Stn. C2 and C3, showing the
decomposition of accumulated mangrove litter. Sato et
al. (1990) demonstrated that ammonium-N was released
with decreasing redox potential from bottom mud which
is rich in mangrove litter by the in situ experiment in a
mangrove swamp in Iriomote Island. Therefore, such a
phytoplankton bloom in the lower part of the creek suggests the utilization of nutrients supplied from the man-
Fig. 6. Salinity, DO, Chl. a and nutrients sections in the creek of Sangga Besar River Estuary for the neap tide (11/11/97).
grove area to the creek, namely, phosphate-P and silicateSi from the creek water and ammonium-N from the bottom water.
Over 80% of the phytoplankton community at the
creek stations (Stn. C1, C2), was dominated by the
dinoflagellate Ceratium kofoidii. In contrast, the Chl. a
maximum in the estuary (Stn. R2) was dominated by
Ceratium kofoidii (36–39%) and needle type Nitzschia
species (34–46%).
3.3 Phytoplankton distribution in spring and neap tide
Figure 7 shows the relationships of salinity to Chl. a
concentration in the estuary for the observation in Oct. to
Dec., 1997. Chl. a concentrations were always below 10
µg/l at salinity less than 13 psu. However, over salinity
13 psu, there were remarkable differences in the concentrations of Chl. a between spring and neap tide. In the
neap tide, peak Chl. a concentrations were below 20
µg/l. In the spring tide, Chl. a concentrations were much
Influences of Nutrient Outwelling from the Mangrove Swamp on the Distribution of Phytoplankton
75
Table 2. Variations in Org-C and Total-N contents (mg/g dry
weight) and Eh (mV) in the surface sediments (0–1 cm) of
the Sangga Besar River Estuary.
Stn.
Org-C
Total-N
C:N atomic ratio
Eh
River
R2
R3
R4
R5
R6
17.3
18.2
18.6
15.4
46.7
2.23
2.15
2.11
1.99
2.80
9.1
9.9
10.3
9.0
19.5
–92
–127
–82
–72
–76
Creek
C2
C3
C4
C5
113.4
86.6
88.7
48.6
2.72
4.77
5.10
3.96
48.7
21.2
20.3
14.3
–216
–314
–146
–64
Fig. 7. Relationship of salinity to Chl. a concentration in the
Sangga Besar River Estuary for the observations in Oct.–
Dec., 1997.
higher, reaching 30–80 µg/l at the intermediate salinity
zone (18–22 psu). This intermediate salinity zone corresponds to the salinity observed in the creek water on 11
Nov., 1997 (Fig. 6), and the high phytoplankton biomass
in the spring tide may reflect the nutrients outwelling from
the mangrove area by the inundation and tidal mixing of
the spring tide. On the other hand, the decrease in
phytoplankton biomass in the neap tide, will be resulted
from the consumption of nutrients, as shown in Fig. 5.
4. Discussion
Relationships between salinity and DIN (NH4 -N +
NO 3 -N + NO 2-N), silicate-Si, and phosphate-P in the
spring (29 Oct., 1996) and neap tide (5 Nov., 1996) are
76
K. Tanaka and P.-S. Choo
Fig. 8. Relationships between salinity and nutrients (DIN,
Si(OH) 4-Si and PO4-P) in the Sangga Besar River Estuary
for the spring (䊉: 29/10/96) and neap (×: 5/11/96) tide.
shown in Fig. 8. In the spring tide, DIN ranged 20–35
µM and decreased slightly with increasing salinity, while
silicate-Si and phosphate-P showed maximum concentrations at intermediate salinity (salinity: 10–20 psu) and
decreased with increasing salinity (salinity >20 psu). In
the neap tide, DIN decreased linearly from fresh water
(up to 35 µM) to estuarine water (below 10 µM) until
salinity 20 psu, and showed a small peak at salinity 23–
25 psu (over 15 µM). This small maximum of DIN at
salinity in the neap tide is reflecting the high nitrite concentrations at the bottom layers of Stn. R4–R6 (Fig. 4).
Neap tide DIN and phosphate-P concentrations were
much lower than those of the spring tide, while the difference was smaller in the case of silicate-Si. As in the
case of DIN, there was a small increase in the concentration of phosphate at salinity 23–25 psu in the neap tide
which will be the results of creek water intrusion. In the
neap tide observation of 1997 (Fig. 5), such higher concentrations of phosphate-P was also observed at the bottom water of Stn. R3.
These non-conservative behaviors of silicate-Si and
phosphate-P with upward curves in the spring tide are
considered to represent the presence of estuarine sources
or outwelling from the mangrove swamp. While downward curvilinearity of DIN and phosphate-P during the
neap tide indicates estuarine sink or biological depletion.
In the spring tide, high water level was almost 1 m higher
than in the neap tide as shown in Fig. 2. The extent of
tidal flat and mangrove areas inundated changes over a
neap-spring cycle. During a neap tide, almost all water is
confined to the main channel. In contrast, the vegetated
mangrove area becomes flooded during a spring tide.
Dissolved inorganic nitrogen in mangrove sediments is
composed mostly of ammonium-N, with lesser amounts
of nitrate-N and nitrite-N (Alongi et al., 1992). The
sediments are also known to be rich in silicate-Si and
phosphate-P. Therefore, in the Matang Mangrove waters,
it is likely that the higher concentrations of ammoniumN, silicate-Si and phosphate-P at the intermediate salinity on the spring tide reflect the tidal flushing of nutrients from the mangrove area.
The peak concentration in ammonium-N and silicateSi on the spring tide was observed at Stn. R4, while that
of phosphate-P was at Stn. R2. This difference in the peak
position will be explained by the desorption of adsorbed
phosphate from the suspended matter because the suspended matter concentration in the spring tide is extremely
higher than that of neap tide (Figs. 3 and 4). Suspended
matter from freshwater inflow brings adsorbed phosphate
on the surface. Actually, suspended matter in the Matang
Mangrove Estuary contains high amounts of inorganic
phosphorus which is released with increasing salinity from
the suspended matter into the estuarine water during the
tidal resuspension and transportation to the sea (Tanaka
et al., 1998).
Concentrations of dissolved inorganic nitrogen are
usually dominated by ammonium-N in tropical mangrove
waters (Alongi et al., 1992). In fact, ammonium-N comprised over 50% of the dissolved inorganic nitrogen in
the Sangga Besar River Estuary in the Matang Mangrove
Forest in the spring tide (Fig. 3). However, in the neap
tide on 5 Nov., 1996 (Fig. 4), nitrite-N was dominant,
exceeding 90% of the dissolved inorganic nitrogen in the
bottom layers of Stn. R6 (up to 12 µM). Such high concentrations of nitrite-N were also observed in estuary (Fig.
5) and creek (Fig. 6) in Nov., 1997 (over 6 µM). While,
the nitrite-N concentrations in the lower salinity surface
water (Stn. R6) and higher salinity water in the mud flat
area (Stn. R1, R2) was below 4 µM. In the observation of
creek (Fig. 6), high nitrite-N concentration was accompanied by the higher DO concentration and higher nitrate
concentration. These observations indicate that nitrite is
produced by nitrification inside the estuary during the
neap tide, which will be mixed with high salinity water
in the mud fat area in the spring tide and will bring about
the higher nitrite-N and nitrate-N concentration in the mud
flat area compared to the neap tide (Figs. 3 and 4). In the
spring tide, phytoplankton biomass is remarkably higher
than the neap tide by the nutrients outwelling from the
mangrove area which will produce high DO concentration. Therefore, the high nitrite concentration in the neap
tide may be explained due to the intrusion of oxygen and
ammonium-N rich salt water inside the sill during the
flood tide and its subsequent nitrification during neap.
Rivers discharge large amounts of suspended matter, originating from the soil erosion of forests and farmlands, which contains large amounts of nutrients (Chase
and Sayles, 1980; Viner, 1982; Tanaka, 1995). During the
dry season in the Sangga Besar River Estuary, particulate
nitrogen and phosphorus in the fresh water area were 34
µM and 5.8 µM, respectively (Tanaka et al., 1998), levels comparable to the dissolved inorganic nutrients in the
wet season. Therefore, in the wet season, the supply of
particulate nitrogen and phosphorus will be much higher
than in dissolved form due to increased runoff loading.
Mangrove swamps trap 99% of land-derived sediments
brought in by runoff in the wet season (Wattayakorn et
al., 1990) before they enter the ocean by outwelling due
to chemical and biological processes (Alongi, 1990;
Alongi et al., 1992).
Mangrove litter is effectively removed from the forest system by tidal flushing, while removal by grazing
and decomposition is minor (Boto and Bunt, 1981). A
large volume of mangrove forest litter accumulates in the
river sediments, especially in the deeply scoured creek
bottom immediately adjacent to the river basin (Table 2),
and becomes another source of regenerated ammonium
by decomposition during the neap tide (Fig. 6).
In the Matang Mangrove Estuary, the maximum concentration of Chl. a in the spring tide reached 80 µg/l. In
contrast, Chl. a concentrations during neap tides were
always below 20 µg/l. The dominant needle type Nitzschia
species in the neap tide have been known to occur
benthically. In well mixed type estuaries, resuspension
of benthic algae from the mud flat causes a linear relationship between Chl. a and suspended matter concentration in the spring tide (Tanaka et al., 1982). However, in
the case of the Matang Mangrove Estuary, there was no
significant correlation between Chl. a and turbidity in the
Influences of Nutrient Outwelling from the Mangrove Swamp on the Distribution of Phytoplankton
77
spring tide (r = 0.04), indicating that the Chl. a maximum was not derived from resuspended sediments. Therefore, such variations in the phytoplankton biomass and
extensive phytoplankton blooms are likely to reflect the
greater nutrient availability due to outwelling from the
mangrove area during the spring tide.
From these results, it appears that the mangrove forests and their creek system support not only nearshore
production by mangrove-derived detritus food chains
(Newell et al., 1995) but also high phytoplankton biomass
in estuarine waters by the fact that nutrient supply in the
mangrove estuary is considerably affected by outwelling
from sediments of the mangrove swamp and creek. However our observations were limited to spring or neap tides
in rainy season, further study is still needed to quantify
the nutrient dynamics in the mangrove estuary.
Acknowledgements
We thank the members of the Fisheries Research Institute (Department of Fisheries, Malaysia) for their support of this work. This work was conducted as a part of
the JIRCAS (Japan International Research Center for
Agricultural Sciences) research project entitled “Productivity and Sustainable Utilization of Brackish Water Mangrove Ecosystems” in collaboration with the University
of Malaya, the Fisheries Research Institute (Department
of Fisheries, Malaysia), and the Forestry Research Institute of Malaysia.
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