Harmful Algal Blooms in Malaysian Waters

Harmful algal blooms (HABs) events have been increasingly reported in the country, not only of the frequency and severity of the events, but also involved more species than previously known. In this paper, a decadal review of HABs events in Malaysia is summarized. Bloom events caused by harmful dinoflagellate species including the shellfish poisoning events were highlighted. Paralytic shellfish poisoning (PSP) is no longer restricted to Sabah coasts and Pyrodnium bahamense. Bloom of Alexandrium minutum was reported for the first time in the Peninsula with six persons hospitalized including one casualty after consuming the contaminated benthic clams. Algal blooms that are associated with incidence of massive fish kills have been reported from both east and west coasts of the Peninsula in conjunction to finfish mariculture loses. The culprits of these bloom events have been identified as the dinoflagellates, Cochlodinium polykrikoides, Neoceratium furca, Prorocentrum minimum, Noctiluca scintillans and a raphidophyte, Chatonella ovata. In this paper, some of these HABs species were characterized morphologically and genetically, including their toxicity. Therefore, with the increase of coastal utilization and eutrophication, prevention, management and mitigation strategies, such as site selection, moving pens, clay spraying should be adopted to minimize the impact of these natural events

The genus Pseudo-nitzschia (Bacillariophyceae) in Malaysia, including new records and a key to species inferred from morphology-based phylogeny

Species of the diatom Pseudo-nitzschia are known to produce domoic acid that is responsible for amnesic shellfish poisoning (ASP). To investigate the potential risk of ASP and species occurrence of toxic or potentially toxic Pseudo-nitzschia in Malaysian waters, plankton samples were collected from 17 locations. Samples were examined through transmission electron microscopy. Species of Pseudo-nitzschia were identified on the basis of the frustule morphology and morphometric measurements. Twentytwo well-described species were recorded, of which 14 are new records for Malaysia. A new morphotype, closely resembling species in the pseudodelicatissima complex, was also discovered. The morphotype differs from other species in the complex by its lower densities of fibulae and striae. Nine of the species have previously been associated with ASP events worldwide. Our study recorded for the first time high species richness of Pseudo-nitzschia in the confined coasts of Malaysia. In addition, we performed a morphology-based phylogeny and proposed a key to Pseudo-nitzschia species, with a special emphasis on the poroid structure of the striae, to aid in species identification

Temperature tolerance and expression of heat shock protein 70 in the toxic dinoflagellate Alexandrium tamarense (Dinophyceae)

The aim of this study was to investigate the relationship between temperature tolerance and geographical origin in a species. Temperature tolerance and heat shock protein 70 (Hsp70) content were investigated in the toxic dinoflagellate Alexandrium tamarense, which was isolated from temperate and tropical areas. Results of treatment at 0–37 8C for 1 h revealed that 15 8C-cultured Japanese A. tamarense could survive treatment at 0–25 8C, whereas 30 and 37 8C treatment reduced the survival rate. Malaysian A. tamarense cultured at 25 8C survived at 30 8C; however, 37 8C and low temperature treatment reduced the survival rate. After acclimation of both strains at 20 8C, they were treated at 0, 4, 30, and 37 8C. The survival rate of Japanese A. tamarense at 30 8C was slightly increased compared to that of 15 8C-cultured cells. Treatment at 37 8C for 1 h showed no difference between acclimated and unacclimated cells of both strains. At 0 and 4 8C treatment, almost all cells of Japanese A. tamarense survived; however, the Malaysian cells were unable to survive. Both strains of A. tamarense, acclimated at 20 8C, were treated at 30 8C; change in the amount of Hsp70 was analyzed. Western blot analysis revealed that the induction of Hsp70 in the Japanese strain occurred more quickly than in the Malaysian strain. These results indicate that Hsp70 of A. tamarense is a heat stress-inducible protein and the response is different between strains

Harmful Algal Species in the Tebrau Strait: An SEM Observation of the Dinofl agellate Assemblage

Harmful algal bloom (HAB) is a natural phenomenon due to the increase of algal cell density in the water column that subsequently causes deleterious effects to natural environments as well as mankind. HABs in the country mainly occurred when a particular group of dinofl agellate cells proliferate in the eutrophied semi-enclosed coastal water body. In this study, dinofl agellate species composition in the Tebrau Strait was determined by scanning electron microscope (SEM). Plankton samples were collected by a 20-micron plankton net haul at several locations of the strait. Samples were undergone fi xation, serial dehydration and followed by critical point drying. Samples were then observed under a JEOL analytical SEM. Total of 11 dinofl agellate species were identifi ed, with 7 species known to be associated with HABs events. The occurrence of a fi sh-killing unarmoured dinofl agellate, Karlodinium venefi cum was reported for the fi rst time from Malaysian waters. The presence of this and other potentially harmful dinofl agellate species in the strait should be taken seriously by the respective authorities in future expansion of aquaculture industry in the strait

Benthic Harmful Dinoflagellate Assemblages In A Fringing Reef Of Sampadi Island, Sarawak, Malaysia

A study on the presence and relative abundance of benthic harmful algal bloom (BHAB) forming dinoflagellate species was carried out in the coral reefs of Sampadi Island, Sarawak, Malaysia. The study involved deployment of fiberglass screens as an artificial substrate for the benthic epiphytic microalgae. The screens were placed for 24 h above the seafloor along a 100 m transect at 10 m intervals. BHAB species attached to the screens were identified and cell abundances were enumerated under a light microscope. The BHAB community at the study site was dominated by Prorocentrum spp. and Coolia spp. Other BHAB species collected included Amphidinium spp., Gambierdiscus spp. and Ostreopsis spp. Total cell densities collected on the screens ranged from 5 to 100 cells per 100 cm2. The two BHAB groups of primary concern, Gambierdiscus spp. and Ostreopsis spp. were detected at relatively low abundances of 0.6–4.2% and 1.8–16% respectively. This study has shown that potentially toxic BHAB species were present in the coral reef and the artificial substrate approach could provide a convenient quantitative method for the collection of clean samples for identification and enumeration purposes

Initial screening of mangrove endophytic fungi for antimicrobial compounds and heavy metal biosorption potential

Endophytic fungi provide protection to their host plant and the fungi often produce antimicrobial compounds to aid the host fighting off pathogens. These bioactive compounds were secondary metabolites which were often produced as waste- or by-products. In the present study, endophytic fungi isolated from mangrove plants and soils were characterized and their antimicrobial production and bioremediation potential of heavy metals copper (Cu) and zinc (Zn) were assessed. Twelve (12) isolated and identified endophytic fungi belonged to seven species; Penicillium, Curvularia, Diaporthe, Aspergillus, Guignardia, Neusartorya and Eupenicillium. Antimicrobial activities of these 12 fungal endophytes were tested against Gram negative bacteria; Bacillus subtilis, Staphylococcus aureus, Gram positive bacteria; Escherichia coli and fungi; Candida albicans and Aspergillus Niger among others. Two isolates (related to Guignardia sp. and Neusartoya sp.) showed strong antimicrobial (and antifungal) activity whereas the rest showed no activity. Compounds were isolated from both isolates and screened using HPLC. Both isolates displayed chemically very interesting chromatograms as they possessed a high diversity of basic chemical structures and peaks over a wide range of polarities, with structures similar to Trimeric catechin and Helenalin among others. For bioremediation assessment, the results showed maximum biosorption capacity for two isolates related to Curvularia sp. and Neusartorya sp., with the former removing 25 mg Cu/g biomass and the latter removing 24 mg Zn/g biomass. Our results indicated the potential of mangrove endophytic fungi in producing bioactive compounds and also highlighted their potential for the treatment of heavy metal-contaminated wastewate

Harmful microalgae assemblage in the aquaculture area of Aman Island, Northen Strait of Malacca

A field survey was carried out in Aman Island, the northern Strait of Malacca, to investigate the occurrence of harmful microalgae. The area is known for marine finfish cage-culture and blood cockle farming. Plankton samples were collected fortnightly between July 2011 and September 2013. A total of 58 phytoplankton genera were recorded; 37 belong to the diatoms, and 21 genera were dinoflagellates. Harmful microalgae species were identified microscopically, of which nine are bloom-forming species that responsible for fish kills. These included Akashiwo sanguinea, Chaetoceros affinis, Cha. curvisetus, Cha. laevis, Ceratium furca, C. fusus, Cochlodinium sp., Karlodinium australe and Noctiluca scintillans. Three Alexandrium species were identified from the samples, i.e. A. leei, A. affine and Alexandrium sp. Pulau Aman; some species in the genus have been known to associate with Paralytic Shellfish Poisoning (PSP). Diarrhetic Shellfish Poisoning (DSP)-toxin producers were also encountered in the water samples, viz. Dinophysis acuminata, D. caudata, Dinophysis sp. and Prorocentrum micans. The harmful diatom, Pseudo-nitzschia spp. that associated with Amnesic Shellfish Poisoning (ASP), was commonly found in the water samples. Cell abundance of each harmful microalga was enumerated. The results showed that cell densities of harmful microalgae were relatively low throughout the sampling period. The microalgae community was dominated by Ceratium furca in May 2012, with cell densities exceeding 70,000 cells L-1; no fish kill event was reported during the time. Even though no fish kill or shellfish poisoning was reported in the area, he presence of harmful microalgae albeit at low cell densities, may pose a potential threat to human health and seafood biosecurity. Therefore, regular phytoplankton monitoring is necessary to safeguard human health and seafood industries in the country

Character evolution of the benthic thecate dinoflagellate, gambierdiscus (Dinophyceae), with an introduction of the interactive key to species

The genus Gambierdiscus is one of the benthic marine dinoflagellates that are known to produce biotoxins, causing ciguatera food poisoning (CFP) in humans after consuming the contaminated marine fishes. These benthic marine dinoflagellates are commonly found in the warm tropical and subtropical waters. The phenomena associated with high cell abundance or “blooms” is referred to Benthic Harmful Algal Blooms (BHABs). Precise species identification is crucial as not all of the species in the genus are toxic. In this study, morphological characteristics of Gambierdiscus species widely used in species identification were analyzed, and the character states coded. Taxon sampling on the large subunit (LSU) rDNA of all Gambierdiscus species were carried out, and used for the phylogenetic reconstruction. The character states were mapped onto the Maximum Parsimony (MP) tree to investigate the character state evolution of Gambierdiscus species. Morphological information and the distribution of the 13 species were used to develop a comprehensive taxonomic database of Gambierdiscus, a web-based interactive identification key for species identification is presented

Phytoplankton community changes in Kuantan Port (Malaysia), with emphasis on the paralytic-shellfish toxin-producing dinoflagellate Alexandrium tamiyavanichii

The Kuantan Port (Pahang, Malaysia, South China Sea) is a multi-cargo port located on the east coast of Peninsular Malaysia. The port has served as an important seaway to major ports in Asia-Pacific regions. In November 2013 and August 2014, two incidents of paralytic shellfish poisoning (PSP) have been consecutively reported in the Port. In this study, a field investigation was undertaken in the Port from April 2015 to May 2016 as an effort to continuously monitor the occurrence of HAB species following the PSP episodes in the year 2013–2014. Phytoplankton and hydrographic samples were collected for quantitative and qualitative assessments in a monthly interval. To precisely quantify the PSP-toxins producing species Alexandrium tamiyavanichii, a real-time quantitative PCR (qPCR) assay was applied to detect the motile cells and cysts. The results revealed the presence of A. tamiyavanichii but with extremely low cell abundances (<0.1% of the total abundances). The species was found co-existed with other Alexandrium species. Alexandrium abundance was associated with salinity and nitrogen to phosphorus ratios but negatively correlated with PO4-P and NH4-N as revealed in the canonical correspondence analysis. Low cell abundances of diarrhetic-shellfish toxins producing dinoflagellates (Dinophysis spp.) and fish-killing species (Prorocentrum sigmoides, Akashiwo sanguinea, Noctiluca scintillans, Chattonella spp.) were also encountered in the port. The results of this study would provide useful baseline information for the assessment and management of ballast water in Malaysian ports and its territorial waters

On-site rapid detection of toxic Alexandrium tamiyavanichii: integrating the species-specific hydrolysis probe in insulated isothermal polymerase chain reaction (iiPCR)

On-site investigation of phytoplankton samples is important for rapid detection of harmful algal species and for early warning of harmful algal bloom. Molecular detection method by DNA amplification in a portable insulated isothermal PCR (iiPCR) device provides a simple and rapid detection based on fluorescent probe within an hour of reaction time. The assay was developed for a paralytic shellfish toxinproducing dinoflagellate Alexandrium tamiyavanichii. The assay presents the data as positive or negative on the presence or absence of A. tamiyavanichii cells, with a limit of detection (LOD) at five target cells per reaction. While the assay is incapable to accurately quantify cell density, it exhibits high detection accuracy and strongly correlated with quantitative PCR (qPCR) data. The user repeatability of iiPCR assay was evaluated; the results showed that no significant differences in the assay run by different operators. Field applicability of the assay was further validated by environmental samples. Despite the shortcoming of the assay, the overall performance of the assay to detect cells, its low-cost effectiveness, and portability for on-site detection, iiPCR has proven its potential as an early screening tool for harmful algae monitoring. Nyuk Fong Kon1 & Winnie Lik Sing Lau2 & Ing Kuo Law2 & Po Teen Lim2 & Chui Pin Leaw