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Spiny lobsters of the family Palinuridae Latreille, 1802 are known to be industrial crustaceans in the global fishing market amongst other crustacean marine species. Panulirus femoristriga has been reported in the Maldives, Japan, Taiwan, Vietnam, the Philippines, Indonesia (Ambon, Irian Jaya, Celebes Island, Seram Island), the Polynesian Islands, Solomon Islands, New Hebrides, Wallis and Futuna and off the coast of northern Australia, but there is uncertainty about their distributions due to the morphological similarity with Panulirus femoristriga, Panulirus longipes bispinosus and Panulirus brunneiflagellum. However, the identification on P. femoristiga can only be confirmed if the morphological descriptions are mentioned in literature.A specimen of the spiny lobster Panulirus femoristriga Von Martens, 1872 was discovered in Semporna, located on the west coast of Sabah State, Malaysia Borneo. While the status of P. femoristriga has been classified as "least concern" on the International Union for Conservation of Nature Red List, studies on the species' population size, habitat and distribution are still inadequate. This study adopted both morphological and molecular approaches for species delimitation.The phylogenetic position of the Sabah P. femoristriga was revealed by the mitochondrial cytochrome c oxidase gene (COI) marker. This represents the first record of the species in the coastal waters of Sabah, despite its wide geographical distribution in the Indo-West Pacific. A revision on the species global distribution was also conducted by harvesting all literature with species named Panulirus longipes femoristriga and Panulirus femoristriga which were available online including those prior to year 2001 before the presence of P. femoristriga is confirmed. Due to the uncertainties on the morphological distribution in previous literature, further studies are required to fill in the missing data for confirmation.

The globally distributed Chaetoceros elegans belongs to the Chaetoceros lorenzianus (C. lorenzianus) complex and is characterized by having tear-shaped setae poroids. Several strains of C. elegans were established from Chinese coastal waters. The vegetative cells and the resting spores were observed using light and electron microscopy. Phylogenetic analyses of two nuclear ribosomal RNA genes (SSU and the D1–D3 region of LSU) and the internal transcribed spacer (ITS) revealed that the C. elegans strains clustered into three clades, corresponding to different morphotypes. Based on the type material, the delineation of C. elegans was amended, and two new taxa, (Chaetoceros macroelegans) C. macroelegans sp. nov. and (Chaetoceros densoelegans) C.densoelegans sp. nov., were described. The two new taxa are featured by the presence of two types of setae poroids, tear-shaped and round-oval setae poroids, whereas only tear-shaped setae poroids are seen in C. elegans. The setae base is distinct in C. elegans, but absent or short in the two new taxa. In C. macroelegans, the tear-shaped poroids on the intercalary setae are larger and less densely spaced than in the other two species. The round-oval setae poroids are more densely spaced in C.densoelegans than in C. macroelegans, although they have more or less the same size. Resting spores characterize the two new taxa, but are unknown in the amended C. elegans. When comparing the ITS2 secondary structure, two and four compensatory base changes (CBCs) distinguish C. elegans from C. macroelegans and C.densoelegans, respectively. Between the two new taxa, no CBC but five hemi-CBCs (HCBCs) are present. The shape, size and density of the setae poroids, as well as the morphology of the resting spores, are important characteristics for species identification among the presently nine known species within the C. lorenzianus complex.

Species of the genus Chattonella (Raphidophyceae) are a group of marine protists that are commonly found in coastal waters. Some are known as harmful microalgae that form noxious blooms and cause massive fish mortality in finfish aquaculture. In Malaysia, blooms of Chattonella have been recorded since the 1980s in the Johor Strait. In this study, two strains of Chattonella were established from the strait, and morphological examination revealed characteristics resembling Chattonella subsalsa. The molecular characterization further confirmed the species' identity as C. subsalsa. To precisely detect the cells of C. subsalsa in the environment, a whole-cell fluorescence in-situ hybridisation (FISH) assay was developed. The species-specific oligonucleotide probes were designed in silico based on the nucleotide sequences of the large subunit (LSU) and internal transcribed spacer 2 (ITS2) of the ribosomal DNA (rDNA). The best candidate signature regions in the LSU-rRNA and ITS2-rDNA were selected based on hybridisation efficiency and probe parameters. The probes were synthesised as biotinylated probes and tested by tyramide signal amplification with FISH (FISH-TSA). The results showed the specificity of the probes toward the target cells. FISH-TSA has been proven to be a potential tool in the detection of harmful algae in the environment and could be applied to the harmful algal monitoring program. [ABSTRACT FROM AUTHOR]

In November 2020, a high biomass multi-species algal bloom caused heavy water discoloration in the fish and mussel farm areas of the Johor Strait, Malaysia. A total of 19 microalgal taxa were identified from the plankton samples collected during the bloom event. Eleven genera were diatoms, and eight genera were dinophytes. The microalgal composition was dominated by the diatom Guinardia sp., with an average cell density of 1.7x106 cells L-1, making up 65-80% of the phytoplankton composition. Concomitantly, high densities of the dinophytes Heterocapsa minima (3.8-5.3×105 cells L-1) and Karlodinium spp. (3.5-6.6×10³ cells L-1) were found. This is the first record of the occurrence of H. minima in Malaysian waters. Detailed morphological observations of H. minima based on scanning electron microscopy are presented in this study. To have a better insight into the Heterocapsa species assemblages in the Johor Strait, the diversity of Heterocapsa species assemblages along the strait was investigated based on a metabarcoding approach. Environmental DNA collected between 2018 and 2019 was used for high throughput amplicon sequencing targeting the small subunit (SSU) ribosomal RNA gene marker. The metabarcoding analysis detected three rare Heterocapsa species in the waters, H. niei, H. rotundata, and H. steinii. The results showed that Heterocapsa species assemblages varied temporally across the strait, with higher species diversity and amplicon sequence variant (ASV) read abundances detected in the Eastern Johor Strait. Although no fish/shellfish kills were sighted during the 2020 bloom event, the presence of harmful microalgal species, such as Heterocapsa minima and Karlodinium spp., urged the need for a comprehensive HAB monitoring program in the Strait to safeguard the aquaculture industry in the areas. [ABSTRACT FROM AUTHOR]

Mass mortality of fish (∼8,500 fishes), mainly Oreochromis placidus, was noted in a man-made lake located at Kuching, Sarawak (Malaysia). A field investigation was conducted to collect water samples and fishes. Patches of discoloration in brick red were observed in the lake and clear oil layer was found on the surface of the water. Microscopic observation and enumeration of the water samples showed that the plankton composition was dominated by a green algal species Botryococcus sp., with the colony densities ranging 1.2×10³ –7.4×106 colonies L−1 . Detailed morphological assessment by light microscopy revealed the dominant species as Botryococcus braunii Kützing. Molecular characterization using an rDNA marker further supported the species identity as B. braunii in the L race. Fish gill observation showed that cells of B. braunii and the oily substances were found in the dead fish gills. The race-L B. braunii bloom was reported, for the first time, to be associated with a fish kill event in a freshwater lake in Malaysia and confirmed the species as one of the algal types causing harmful effects to the environment. [ABSTRACT FROM AUTHOR]

A survey of marine phytoplankton in the Singapore Strait was carried out between May and June 2013, as part of an effort to determine the diversity of phytoplankton in Singapore's coastal waters. A total of 34 microalgal samples were collected using a 20 μm-mesh plankton net and from coastal sediments. Living samples and preserved samples in Lugol's solution were identified to species as far as possible under the microscope. A checklist of marine micro-phytoplankton was updated to encompass 270 taxa, including 49 new records from Singapore waters. Some 37 species from 15 families were dinoflagellates, and 233 species from 50 families were diatoms. Harmful microalgae, categorized as biotoxin-producers and fish killers, were also found in this survey. These were in the genera Alexandrium, Amphidinium, Ceratium, Cochlodinium, Coolia, Dinophysis, Gambierdiscus, Karenia, Karlodinium, Ostreopsis, Prorocentrum, Nitzschia, and Pseudo-nitzschia. [ABSTRACT FROM AUTHOR]

We explored the 18S rDNA sequences of Pseudo-nitzsihia and its close relatives, together with their individual secondary structure information to reconstruct phylogenies. Forty-eight taxa classified in the Bacillariaceae and Achnanthaceae were analyzed by character-based (maximum parsimony and maximum likelihood) and distance-based (neighbour-joining) methods. Three raphid diatoms from the Eunotiaceae were used as out-groups. The sequence-structure alignment was generated by 4SALE (i.e. a one-letter encoded alignment that contained the individual secondary structure information) and applied to the character-based phylogeny reconstruction. All analyses highly support Pseudo-nitzschia + Fragilariopsis as monophyletic. The Pseudo-nitzschia/Fragilariopsis clade is further divided into three subclades. One clade comprises members in the P. seriata and P. americana complexes and species of Fragilariopsis; the second and third clades constitute members in P. pseudodelicatissima and P. delicatissima complexes. Among all analyses, the distance-based method yielded a more highly resolved phylogenetic framework for the Pseudo-nitzschia + Fragilariopsis cladc than did the character-based analyses. Other than those currently known genetic markers, 18S rDNA was also useful in exploring the intrageneric relationships. [ABSTRACT FROM AUTHOR]

Pseudo-nitzschia pungens is a planktonic marine diatom known to be widespread in tropical and temperate coastal waters. We examined the population genetic structure of tropical Southeast Asian populations of P. pungens and compared it with those of northern and southern temperate populations. The secondary structures of the nuclear encoded internal transcribed spacer (ITS) region of 164 strains of P. pungens were modeled and analyzed. The tree revealed three ITS entities: clade I (comprised of P. pungens var. pungens) was distributed mainly in northern temperate waters; clade II (comprised of both P. pungens var. pungens and var. cingulata) was mainly from the NE Pacific; and clade III (comprised of both P. pungens var. pungens and var. aveirensis) was restricted to tropical and warm-temperate waters. Hybrids of both P. pungens var. pungens and var. cingulata co-occurred in clades I and II. Sixty haplotypes were revealed from the sequences of 164 strains. Haplotype diversity inferred from the median-joining network was in accordance with phylogenetic analysis, further supporting the grouping of the P. pungens haplogroups. Our results revealed limited gene flow between P. pungens from tropical and temperate waters, and significant population structure, as estimated by an analysis of molecular variance (AMOVA), with 75% of the total ITS variation found among populations (ФST = 0.75). This study suggests that distinct environmental clines, such as ocean thermohaline circulation, have a potential for fragmenting and dispersing global populations of P. pungens. Formation of the Isthmus of Panama, in particular, is speculated to play a role in this allopatric differentiation in P. pungens populations worldwide. [ABSTRACT FROM AUTHOR]