Composition and diversity of phytoplankton from mangrove estuaries in Sarawak, Malaysia

The composition and diversity of phytoplankton were studied along with physico-chemical parameters of water of two mangrove-dominated estuaries i.e., Kuala Sibuti (KS) and Kuala Nyalau (KN), Sarawak, Malaysia. A total of 46 species of phytoplankton with the mean density of 147000 cells L-1 were recorded from KS estuary i.e., 3 species of Cyanophyceae; 22 species of Bacillariophyceae; 20 species of Dinophyceae and 1 species of Chlorophyceae. The recorded mean density of phytoplankton was 113000 cells L-1 with 33 species from 19 genera from KN estuary, in which 19 species were from Bacillariophyceae; 12 species were from Dinophyceae; 1 species was from Cyanophyceae and 1 species was from Chlorophyceae. In both the estuaries, the species composition was found to be in an order of Diatom>Dinoflagellate>Cyanophyceae>Chlorophyceae. Canonical Correspondence Analysis (CCA) revealed that the abundance of Bacillariophyceae and Dinoflagellates was influenced by salinity and conductivity along with ammonium and phosphate while the abundance of Chlorophyceae was influenced by temperature, TDS, DO and pH in KS. The influence of salinity and conductivity along with PO4 and NH4 on the abundance of Bacillariophyceae, Dinoflagellates and Chlorophyceae were observed in KN

Seasonal variation of water characteristics in Kuala Sibuti river estuary in Miri, Sarawak, Malaysia

This paper presents the water characteristics of Kuala Sibuti river estuary, which is margined by pristine mangrove forest. For this purpose, nutrients, chlorophyll a and environmental parameters were investigated for 12 months. Physical, chemical and biological parameters of this estuarine water followed a seasonal rhythm and induced by the annual cycle of the monsoon. Surface water temperature ranged from 27.4°C to 32.2°C with a wide variety of salinity from 0.70 PSU to 27.10 PSU followed by Dissolved Oxygen (DO) from 1.94 to 6.71 mg/L. The concentration of chlorophyll a was found to be varied from 0.02 to 0.16 mg/m3. Nitrate, phosphate and ammonium concentrations ranged from 0.40 to 3.53mg/L, 0.01 to 1.92 mg/L and 0.06 to 1.24 mg/L, respectively. Pearson correlation coefficients showed a significant relationship between nitrate and TDS, nitrate and pH, ammonium and salinity, temperature and salinity, temperature and TDS, phosphate and light attenuation in this estuarine environment. The estuary was found to be mesohaline in nature. Estuarine Water Quality Index (EWQI) calculated from phosphate (PO4), suspended matter (SM) and dissolved oxygen (DO) indicate very good quality (4.95). Significantly seasonal difference for salinity, water temperature and, TDS were observed probably related to tidal flow and upstream river runoff

Distribution of aquatic macrophytes in the coastal area of Salimpur, Chittagong, Bangladesh.

This preliminary study was conducted to investigate the distribution pattern of the aquatic macrophytes in the inter-tidal coastal belt of Salimpur, Chittagong. During this study, 3 species of mangrove, i.e., Sonaratia apetala, Avicennia marina and Acanthus ilicifolius, 1 species of wild rice related to salt marsh grass, i.e., Porteresia coarctata, 3 species of macro-algae, i.e., Ulva intestinalis, Catenella nipae and Dictyota dichotoma and 1 species of poison lily Crinum defixum were identified from this coast. The dominant macrophyte was planted Sonaratia apetala, followed by Porteresia coarctata in the coast line of Salimpur. Considering from the ecological and economic view, especially Catenella nipae, could be an important living resource for cultivation and sea ranching in this area. Besides, the importance of these aquatic inter-tidal macrophytes for fishery resources and overall ecosystem processes should not be over looked in this coastal area

Growth and survival of Indian salmon Eleutheronema tetradactylum (Shaw, 1804) in Brackish water pond.

This study was conducted to assess the growth performance and survival rate of a commercially important finfish Eleutheronema tetradactylum in 100 m-2 of sandy clay brackish water earthen ponds. Wild 36.14 g of E. tetradactylum juveniles were stocked at 0.5 individuals m-2 and cultured for 45 days by feeding trash Muraenesox sp. (pike eel) at 12 h intervals. Average body weight of E. tetradactylum was found 75±5.6 g for treatment ponds and 65±3.57 g for control ponds at the end of experiment. Feed Conversion Ratio (FCR) was 2.3 with the survival rate of 70-80% at the end of the culture in the experimental culture ponds. The results of the present study suggest that the production of four finger thread fin could still be increased up to the marketable size if it is done for 5-6 months culture period by feeding trash fish

Phytoplankton in tropical mangrove estuaries: role and interdependency

Mangrove estuaries are claimed to be productive and important breeding grounds for fishery resources. The role of particulate organic matter (POM), especially derived from decomposed litter detritus, is well documented in mangrove estuaries. However, being a primary producer, phytoplankton may play a significant role, which has not been well discussed, in governing the productivity of mangrove estuaries. Based on relevant published literature, this paper focuses on the role of phytoplankton in mangrove estuaries in the tropical coastal region and their interdependency. Analysis reveals that there are two-way interactions between phytoplankton and mangrove estuaries. The POM enriched water in mangrove estuaries acts as an ideal medium for phytoplankton succession. Simultaneously, diversified phytoplankton assemblages play a significant role in the food web of the estuarine mangrove ecosystem. Biomass and diversity of phytoplankton are influenced by nutrient and environmental parameters in mangrove estuaries and, concurrently, phytoplankton play a significant role in fish diversity and primary production in the same system. This review reveals that the inconsistent relationships between mangroves and coastal production could probably be due to the influence of seasonal changes. This paper unveils the latent potential and role of phytoplankton in tropical mangrove estuaries, which could be a source of thought for future research in this arena

Seasonal distribution of zooplankton composition and abundance in a sub-tropical mangrove and salt marsh estuary

Zooplankton composition and abundance at two stations located in exposed (station I) and protected (station II) areas of Bakkhali sub-tropical estuary, Cox's Bazar, Bangladesh were investigated monthly from January 2006 to December 2006. Thirty-three zooplankton taxa were identified. The major groups of zooplankton encountered were Copepoda, Chaetognatha, Mysidaceae, Luciferidae, Amphipoda, Acetes, Hydromedusae, Cladoceran, Decapod and fish larvae. The percent composition of Copepoda was the highest (79.5-84.8%) among zooplankton groups followed by Chaetognatha (5.5-6.0%) and Mysidaceae (3.3-6.8%). The abundance of zooplankton was relatively higher (87674individuals/m3) in protected (mangrove) as compared to exposed (salt marsh; 68719 individuals/m3) site during the study period. Canonical Correspondence Analysis indicated that the abundance of copepods was influenced by rainfall, water temperature and transparency in this estuarine environment, and considered coastal and estuarine dominant

Trends in Seagrass Research and Conservation in Malaysian Waters

The seagrass ecosystems found in the marine and coastal areas, with substantial economic and ecological services and span all over the globe excluding the Antarctic region. The Coral Triangle and Southeast Asia are recognized as a worldwide hotspot of seagrass species and habitats, encompassing 10-21 species of seagrass in every nation, although the study, understanding, and quantity of publications on seagrass ecosystems are rather limited in the region, including Malaysia. Malaysia contains 18 seagrass species from three families, which occupy 16.8 km2 of coastal area, where the study and discovery of seagrass species and meadows began in 1904 with the report of Beccari. All of the published papers reviewed reported on Malaysian seagrass-related research, which was divided into nine topic groups: biology and distribution, carbon sequestration, fauna, remote sensing, impact and pollution genetic study, restoration, microbiological investigation, and others. The extensive study of the seagrass ecosystem began in 1993, and we have identified 183 published papers from Scopus, 141 publications from Web of Science, and 42 from Google Scholar. However, the average trend of the number of publications from 1993 to 1999 was 0.71 ± 0.36, while from 2000 to 2022 was 7.70 ± 1.16 followed by the average trend of the yearly number of publications was 6.78 ± 1.08. The highest number of publications was found on faunal categories (43.17%), followed by biology and distribution (21.85%). The number of articles that were published on Malaysian seagrass meadows each year has been discovered to be rising, which indicates that the trends in seagrass study and publishing were progressively garnering the attention of researchers, academics, and the government. However, to better understand the sustainable ecology and ecosystem services provided by seagrass habitats, an emphasis on certain research niches, such as the genetic study of flora and fauna in seagrass meadows, microbial ecology, and restoration as well as conservation of seagrass species might be helpful.22 página

Community composition and diversity of phytoplankton in relation to environmental variables and seasonability in a tropical mangrove estuary

This paper presents the aspects of phytoplankton communities along a tropical mangrove estuary inSarawak, Malaysia. Data were collected monthly from the study area from January 2013 to December2013 and was pooled into seasons to examine the influence of seasonality. The estuary revealedrelatively species-rich, and a total of 102 species under 43 genera were recorded comprising 6 speciesof Cyanophyceae; 4 species of Chlorophyceae; 62 species of Bacillariophyceae and 30 species ofDinophyceae. The species composition, as well as the mean abundance (cellsL-1) of phytoplankton,were found in order of Bacillariophyceae>Dinophyceae> Cyanophyceae> Chlorophyceae. Mean abun-dance of phytoplankton ranged from 5694 to 88890 cellsL−1over the study period with its highervalue in the dry season. Species recorded from the estuary were dominated byPleurosigma normanii,Coscinodiscussp,Coscinodiscus centralis,Coscinodiscus granii,Dinophysis caudata,Ceratium carriense,Ceratium fusus, andCeratium lineatum. Abundance of phytoplankton demonstrated positive correlationwith chlorophylla(r=0.69), ammonium (r=0.64) and silica (r=0.64). Significant differences (ANOSIMand nMDS) were observed in the species community structure between intermediate and the wetseason. Canonical correspondence analysis (CCA) showed that most of the species assemblages werepositively correlated with surface water temperature, salinity, pH, ammonium and nitrate in theintermediate and dry season towards larger species composition in the respective seasons whereassilica showed influence on the species assemblage in the wet season. The findings suggest that theSibuti mangrove estuary is productive in terms of diversified phytoplanktons and their variability inassemblage, those are influenced by the hydrological and biological factors

Can mangroves help combat sea level rise through sediment accretion and accumulation?

Mangroves have substantial roles to induce sedimentation in the vulnerable coastal regions, which subsequently helps to combat climate change induced impacts like sea level rise. Although Sarawak has numerous pristine estuarine mangroves, studies on the roles of these mangroves in regards to sediment deposition are scanty. Therefore, this study was carried out to determine the sediment accretion and accumulation pattern of pristine Sibuti mangrove using tiles and sediment traps from January to December 2013. Monthly average accretion and accumulation rate of sediments of this mangrove were 0.55 mm and 0.08 g cm-2, respectively. A total of 6.56 mm and 0.93 g cm-2 sediments were accreted and accumulated annually. Significantly positive correlation (r=0.794) was found for the monthly accretion of sediments with accumulation. Accretion and accumulation of sediments were also positively correlated with rainfall. Comparatively higher rate of accretion and accumulation of sediments were estimated in the months of wet season when the rainfall and tidal inundation duration were high. Erosion was found higher in the months of dry season when the rainfall was low. Seasonal variations were not found for sediment accretion as well as accumulation in the study area. The findings of the study suggest that the roles of this forest in regards to sediment accretion through retention is compatible with the predicted annual rate of sea level rise of 1.8 to 5.9 mm within 21st century by IPCC