A study was carried out to determine the temporal and spatial distribution of nutrients and Harmful Algal Blooming species (HABs) to establish the relationship between nutrient concentrations and HABs density in the coastal water of Kota Belud, Sabah, Malaysia. Eight stations were set up in four transects (each transect had two stations; one 500 meters seawards from shoreline, and another five kilometers seawards from shoreline) along the Kota Belud coastal area. Phytoplankton samples, water samples and in situ environmental parameters were collected during dry and wet seasons. Altogether nine HABs species were identified from the study area, where six species ( Pyrodinium bahamense, Prorocentum micans, Neoceratium furca, Prorocentum sigmoides, Dinophysis caudate, and Neoceratium fursus) belonged to Dinophyceae and three species ( Thalassionema nitzchoioides, Chatoceros affinis, Rhizosolenia sp.) belonged to Bacillariophyceae. Among nine species, Chatoceros affinis was the most abundance composed of 80.6% of total species recorded from all stations during study period. Among the toxic producing Dinoflagellate, Pyrodinium bahamense bloom (>10 3 cells/l) was observed during study period. Trong linear relationship (r 2 = 0.80) was observed between the cell density and concentration of nitrate nitrogen. Relationship between cell density and phosphate phosphorus was poor (r 2 = 0.51). The study showed that increasing in nutrient concentrations resulted in the increasing of HABs density. Nitrate was seen to be more important than phosphate in Kota Belud water as limiting factor of the growth of HABs.
Harmful Algal Bloom (HAB) is the process of sudden increase in the biomass of cells that can bring negative impact on the aquatic organism living that environment. Pyrodinium bahamense var. compressum, Alexandrium spp, Karlodinium veneficum and Gymnodinium are the most common HABs species in Malaysian water [
The west coast of Sabah in Malaysia experiences annual harmful algal blooming. West coast of Sabah is an important agriculture region. High nutrient runoff from agriculture field results in harmful algal blooms. Because of this reason, harmful algal bloom monitoring programs are concentrated on the west coast of Sabah particularly in Kimanis bay [
Kota Belud is located in the Southeast of South China Sea and Northwest of Sabah (
Abai and Tempasuk River. The mangroves at the mouth of Bira Biraan River have been cleared for aquaculture. Kuala Abai and Kuala Tempasuk are the two outlets of a major river system that drains a large part of the north western part of Mount Kinabalu, discharge relatively large sediment plumes, whereas Kuala Rampayan at the northern part carry less sediments [
Sampling locations of this study consists of four transects where each transect consists of two stations which was located at 0.5 km and 5 km away from the land toward the sea. Station A1 and station A2 in transect A were located at the mouth of Abai River (the largest coverage of mangrove). Station B1 and station B2 in transect B were located at the river mouth of Tempasuk River which carry the largest sediment plumes from Mount Kinabalu. Station C1 and C2 in transect C were located at the river mouth of Bira Biraan which was dominated by agriculture activities. Station D1 and station D2 in transect D were located in the Kuala Rampayan that carry minute sediment. Sampling was done September (dry season) to December (wet season).
Environmental parameters including temperature (˚C), salinity (psu), dissolved oxygen (%), turbidity and pH value in each of stations were taken by using a multi-function environmental sensor.
Surface seawater from each station was collected to a depth of 0.5 m from surface. One Liter of water sample was filtered through 0.45 µm pore-size membrane filters, and stored frozen until analyzed. Another ten Liter of water sample passed through the phytoplankton net having mesh size of 20 µm and was collected in 500 ml plastic bottle and immediately preserved with Lugol’s solution.
Phytoplankton was collected by towing plankton net with 20 µm mesh size to a depth intermediate of 0.5 m. Then, the concentrated phytoplankton was transferred to a bottle and preserved with Lugol’s iodine for microscopic analysis in the laboratory.
The dissolved inorganic nutrients concentration of NO3-N, and PO4-P were analyzed in the laboratory at Borneo Marine Research Institute, University Malaysia Sabah, using the spectrophotometric methods [
In the laboratory cells counting were performed by using Sedwick rafter method and cell density was estimated by using Stirling cell density formula.
where
N: No. of plankton cells per liter of original water
A: no. of plankton counted
F: total volume (ml) of sample counted
Statistical Analysis
Statistical analyses were performed using the SPSS Windows Statistical Package (Version 19.0). Tests were judged with significant at p < 0.05 level. All variables were tested for normality and homogeneity of variances. Data which satisfy the assumptions of normality and homogeneity, parametric tests (one-way ANOVA, Independent t-test, and Pearson correlation test) were performed.
During the dry season, the physical water quality parameters of Kota Belud’s coastal water were relatively constant at all the stations (
Wider range in the physical water quality parameters were noticed during wet season in the study area. The saturation in dissolved oxygen, value of pH, temperature, salinity and transparency were ranged from 101.1 to 106.5%, 8.22‰ to 8.33‰, 24.4‰ to 29.8‰, 30.0˚C to 30.7˚C and 1.0 to 11.0 m, respectively. There were no significant (p > 0.05) in dissolved oxygen, pH and temperature were recorded among all stations. However, salinity and transparency level at station B1 and B2 were comparatively lower and higher, respectively than salinity recorded from other stations (A1, A2, C1, C2, D1 and D2).
The concentrations of NO3-N in study area during dry season were in the range of 0.032 to 0.049 mg/l, but atwet season the values were in the range of 0.038 to 0.070 mg/l (
Dissolve oxygen (%) | pH | Salinity (‰) | Temp (˚C) | Visibility (m) | ||
---|---|---|---|---|---|---|
Dry season | A1 | 111.5 | 8.20 | 29.2 | 30.9 | 10.0 |
A2 | 101.4 | 8.13 | 29.3 | 30.7 | 10.0 | |
B1 | 100.9 | 8.21 | 29.2 | 30.6 | 10.0 | |
B2 | 111.9 | 8.22 | 29.0 | 30.6 | 14.5 | |
C1 | 114.7 | 8.22 | 28.9 | 30.4 | 12.0 | |
C2 | 113.2 | 8.22 | 28.9 | 30.4 | 13.0 | |
D1 | 111.2 | 8.22 | 29.4 | 30.5 | 10.5 | |
D2 | 114.0 | 8.20 | 29.1 | 30.3 | 10.0 | |
Wet season | A1 | 102.6 | 8.30 | 29.8 | 30.7 | 6.0 |
A2 | 104.8 | 8.33 | 27.9 | 30.1 | 8.5 | |
B1 | 102.1 | 8.22 | 22.8 | 30.5 | 1.0 | |
B2 | 101.9 | 8.30 | 24.4 | 30.4 | 1.5 | |
C1 | 104.3 | 8.31 | 29.2 | 30.5 | 7.0 | |
C2 | 106.5 | 8.32 | 29.0 | 30.5 | 8.0 | |
D1 | 101.1 | 8.31 | 28.6 | 30.0 | 8.0 | |
D2 | 105.8 | 8.31 | 28.5 | 30.0 | 11.0 |
0.003 mg/l nitrate at station B1 was significantly higher (p < 0.05) than the concentration obtained at station B2 compared to other stations at the wet season. Comparatively the higher concentrations of NO3-N were observed in all station during wet season (
Concentration of phosphate in Kota Belud’s coastal water was ranged from 0.007 to 0.008 mg/l and 0.007 to 0.030 mg/l during dry season and wet season, respectively (
A total of nine harmful algal bloom species were identified at coastal water of Kota Belud. Six species (Pyrodinium bahamense, Prorocentum micans, Neoceratium furca, Prorocentum sigmoides, Dinophysis caudate, and Neoceratium fursus) belongs to Dinophyceae and three species (Thalassionema nitzchoioides, Chatoceros affinis, and Rhizosolenia sp.) belong to Bacillariophyceae. The most dominated species was Chatoceros affinis (80.61% of the total count of 24.04 × 104 cells/l) which showed the highest percentage of cell density during both at dry and wet season in the study area. The second dominated species was Thalassionema nitzchoioides constituted of 12.76% of the total count of 24.04 × 104 cells/l. (
HABs species | Total count (×104 cells/l) | ||||
---|---|---|---|---|---|
Cell density at dry season (×104 cells/l) | Cell density at wet season (×104 cells/l) | ||||
Bacillariophycaeyceae | Chatoceros affinis | 19.377 | 0.891 | 18.486 | |
Thalassionema nitzchoioides | 3.068 | 0.215 | 2.853 | ||
Rhizosolenia sp. | 0.033 | 0.007 | 0.026 | ||
Dinophyceae | Pyrodinium bahamense | 0.349 | 0.013 | 0.336 | |
Prorocentum micans | 0.173 | 0.021 | 0.152 | ||
Neoceratium furca | 0.518 | 0.023 | 0.495 | ||
Prorocentum sigmoides | 0.009 | 0.000 | 0.009 | ||
Dinophysis caudate | 0.122 | 0.030 | 0.092 | ||
Neoceratium fursus | 0.390 | 0.054 | 0.336 | ||
Total no of cell (×104 cells/L) | 24.039 | 1.254 | 22.785 | ||
The highest harmful algal blooms cell density of (5.01 ± 0.50 × 104cells/l) was observed at wet season in station A1. This value was significantly higher (p < 0.05) than the cell density of HABs species from wet season from other stations, except station B1 and B2. However, HABs cell density in transect A (A1 and A2), C (C1 and C2) and D (D1 and D2) were significantly higher (p < 0.05) at wet season compared to the cell density of the HABs species collected at dry season.
The HABs density was strongly influenced by nutrient concentration where increase in nutrients (nitrate and phosphate) concentration associated with increase in HABs cells density. Nitrate concentration showed a strong positive corellation with HABs density (R2 = 0.802), while a weak positive correlation between phosphate and HABs density (R2 = 0.514) was observed (Figures 4-6).
Current study shows no significant spatial differences in temperature, Secchi depth, pH, Secchi depth (visibility), salinity and dissolved oxygen observed among all 8 stations at dry season. This might be must be due to a small area covered and lack of sample frequency, which was only the limitation of this study. However, spatial differences in salinity and visibility were recorded in station B1 and B2 during wet season. Surface runoff of sediment and discharge of river directly causes the lower visibility in water and the lowest salinity Average rainfall at Kota Belud during dry season was 280 mm while average rainfall during wet season was 400 mm [
The range of nitrate concentration of 0.032 to 0.07 mg/l and range of phosphate concentration of 0.007 to 0.03 mg/l were recorded in Kota Belud’s coastal water. Comparable concentration of 0.019 to 0.09 mg/l of nitrate was determined coastal water of North-East Langkawi [
Nitrate concentration showed no significant different in transect A, C and D between dry and wet seasons. However, nitrate concentration in transect B (station B1 and B2) was relatively higher than that in nutrients concentration in other transects at wet season. Nutrients in these stations are influence by the surface runoff of surrounding areas and also down pour from the Tempasuk River. Tempasuk River is surrounded by mangrove forest, agriculture field, and Mount Kinabalu [
Phosphate concentration was similar in all station at dry season. It may be mentioned here that, the surface phosphate concentrations of the stations 0.5 km away from the coast line (A1, B1, C1 and D1) were higher during wet season compared to dry season. Nitrate and phosphorus loading is dependent on land use, fertilizer application, population density in addition to release from aquaculture activity [
Phytoplankton community of Kota Belud water was dominated by diatoms (93.51%) in term of genus density compared to Dinoflagellates (6.49%). Diatoms accounted for 77% of total phytoplankton in marine ecosystem [
The cell density of Pyrodinium bahamense, the paralytic shellfish poisoning (PSP) producing Dinoflagellates, in the coastal water of Kota Belud was 3.36 × 103 cells/l at wet season. HABs consider occur when the cell density of dominant species is higher than 106cells/l for non-toxic production species and higher than 103 cells/l for toxic production species [
Abundance of HABs was found to be highest (5.01 ± 0.50 × 104 cells/l) at station A1 which was located in front of Abai River that discharges fresh water from the western part of Mt. Kinabalu. Abai River not only carried sediment plumes from Mount Kinabalu but also nutrients from the large mangrove forest coverage along the Abai River [
Total HABs cell density in transect A (A1 and A2), C (C1 and C2) and D (D1 and D2) at wet season were significantly higher than that in HABs density recorded at dry season. Similar observation was documented in previous study where phytoplankton density was significantly higher during Northeast monsoon (26.38 × 106 cells/l) than Interseasonal monsoon (23.98 × 106 cells/l) in Sepangar Bay, Sabah [
Interestingly, although the nutrients concentration was significantly high in wet season than in dry season at transect B. But no significant difference was observed in HABs cell density at transect B (B1 and B2) between dry season and wet season. The reason of this was low salinity in transect B limiting the HABs bloom. In agreement with Anton et al. [
This study shows HABs densities were noticeably higher in higher nutrient levels. HABs have been known to occur often in nutrient-rich coastal water such as ports, estuaries, and bays [
This study shows Nitrate concentration showed stronger relationship with HABs density (R2 = 0.802) compared to the relationship between phosphate and HABs density (R2 = 0.514). Enrichment in nitrogen particularly nitrate lead to an increase in phytoplankton biomass in marine habitat [
This study has discovered that at least nine HABs or potential HABs species have been confirmed in Kota Belud water, namely Chatoceros affinis, Thalassionema nitzchoioides, Rhizosolenia sp., Pyrodinium bahamense, Prorocentum micans, Neoceratium furca, Prorocentum sigmoides, Dinophysis caudate, and Neoceratium fursus. Although 9 species were found in Kota Belud water year-round however only Pyrodinium bahamense bloom (cell density >103 cells/l for toxic production species) took place during this study.
Cell density of harmful algal bloom in Kota Belud was higher in wet season. Runoff after heavy precipitation initially resulted in increased accumulation of nutrients (nitrate and phosphate) concentration in the estuary. Increasing in nutrients concentration was generally associated with increasing of HABs cell density. This study also discovered that nitrate was limiting factor for HABs cells density rather than phosphate in Kota Belud’s coastal water.
This study was supported by University Malaysia Sabah. This work would not have been possible without the support of from Borneo Marine Research Institute staffs.
Sujjat Al Azad,Sitti Raehanah Muhamad Shaleh,Tan Kar Soon, (2016) Temporal and Spatial Distribution of Nutrients and HABs at Coastal Water of Kota Belud, Sabah. Advances in Bioscience and Biotechnology,07,233-242. doi: 10.4236/abb.2016.75022