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Johor Strait has received massive anthropogenic traffic in recent years, causing environmental alteration and inevitably harming macrobenthos on the seafloor. A comprehensive assessment was done in several key locations within the strait to identify macrobenthic inhabitants and possible driving factors attributing to differences in macrobenthic assemblages in these areas. Sediments were acquired using Ponar Grab in 13 key locations within the Johor Straits. Seven hundred thirty macrobenthic individuals and 46 known taxa were identified in sediments of 13 locations in the strait. Annelids Prionospio (n=295), Minuspio (n=95) and Mediomastus (n=82) were concentrated in the central zone. Molluscs dominated the Merambong Shoals area (Arcualuta, n=66), and amphipods dominated waters off Santi River (Leucothoe, n=26; Gammarus, n=11; Cymadusa, n=9). PERMANOVA analyses (p<0.05) showed significant differences in benthic taxa composition in all locations overall. BIOENV analyses (r=0.76, p<0.05) highlighted water acidity, chlorophyll-a, silts and total organic carbon as the main influences toward benthic assemblages throughout the study area. PCA graph indicated higher organic carbon and silts in the central area, implying favourable conditions for Sedentarian polychaetes to thrive. The east and west ends of the strait exhibited higher readings of water acidity and chlorophyll-a, which may directly contribute to a higher diversity of benthic communities in the areas. Lower oxygen levels in two locations in the central area (J3=2.97 mg/L, J4: 2.63 mg/L) exhibited Sedentaria polychaete-dominated region, but zero benthic organisms in another part of the central area (J5-J9, 2.97–0.99 mg/L). This study showcased the effectiveness of environmental monitoring using macrobenthos as an indicating subject. [ABSTRACT FROM AUTHOR]

Continuous evaluation and monitoring of coral percentage cover and health status is critical for enhancing coral reef resilience management. The present study aimed to determine the coverage and coral status at important sites of Tioman Island Marine Park, which include Renggis Island, Tiong Point and Tekek. Surveillance video recording and in situ observation were carried out using the Coral Video Transect (CVT) method, which were analyzed using the Coral Point Count with Excel extension (CPCe) software. The overall health status for the study area was considered as “fair” with 41.61% ± 4.46% of mean live coral coverage. Among the stations Renggis Island had the highest live coral coverage accounting for 50.71% ± 6.97%, which was classified as ‘good’. In terms of coral diversity, a total of 11 families and 36 genera were identified for the three sampling sites. Family Acroporidae, which includes the Acropora, Anacropora and Montipora, dominated the coral reef within the study area with 17.09% ± 2.54% coverage. Acropora was the most abundant with 12.40% ± 3.66% coverage, followed by Porites (11.31% ± 1.33%), Leptoseris (5.12% ± 5.09%), Montipora (4.69% ± 3.43%) and Sinularia (2.58% ± 2.33%). In terms of conservation, Renggis Island and Tiong Point were categorized as Conservation Class 4 (CC-4), which indicates great diversity of species, while Tekek was in Conservation Class 2 (CC-2). Tiong Point has the highest diversity (H’ = 1.64) and good evenness values (J = 0.64), but it also recorded a high mortality index (MI = 0.55). Tekek on the other hand, recorded the lowest diversity (H’ = 1.26) and poor evenness (J = 0.44), with the highest mortality index (MI = 0.59). In conclusion, some of the reef areas on Tioman Island were not in the best condition, thus efforts should be taken to enhance coral reef resilience that may improve coral reef conservation and preservation. [ABSTRACT FROM AUTHOR]

Increased acidification has shown to bring negative impacts on marine fish. Currently, fish with scales have been extensively investigated, whereas a few systematic studies have been carried out for investigating impacts of acidified environment towards the growth of scaleless fish. Thus, this research aimed to evaluate carbon dioxide, CO2‐induced acidification impacts towards the welfare (growth with health) of the commercially aquaculture scaleless fish, Sagor catfish (Hexanematichthys sagor) for 20 weeks. Fish specimens were exposed to control pCO2 (400 µatm), mild pCO2 (550 µatm) and high pCO2 (900 µatm). Growth were measured by feed conversion ratio (FCR) plus specific growth rate (SGR). The outcomes indicated that the significantly lowest SGR was flaunted in high pCO2 group supported with the significantly highest FCR indicating poor growth. Health parameters significantly showed the highest value of red blood cell, haematocrit, haemoglobin, white blood cell, thrombocyte, mean corpuscular volume and haemoglobin in control group while urea, cholesterol, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, lactate dehydrogenase, serum cortisol plus glucose were significantly the lowest in control pCO2 with regard to mild and high pCO2 group. These findings can serve as important baseline data in formulating managements regarding the specific effects of acidification on scaleless fish. [ABSTRACT FROM AUTHOR]

Trait assessment is an alternative but effective method of biomonitoring benthic community in ecosystem, but it was rarely done in Malaysia. An assessment was done to identify the dominant sub-traits, or modalities, within benthic community in seafloor northwards of Pulau Indah, Klang, Malaysia, and to establish possible correlation between modalities with environmental parameters measured in the area. Sampling was conducted in November 2018, during Northwest Monsoon season. Sediments were obtained by using a Ponar Grab and filtered through 500 µm sieve. Sediments were subjected into Loss of Ignition method to extract organic carbon, and filtration method to determine particle size distribution percentages. 37 taxa were recorded in this study, totalling to 848 individuals. Traits assessment indicated vermiform body shape, direct larval development, deposit feeder, non-motile, asexual reproduction, and second-order opportunistic group as most dominant modalities in the study area. Station 1 recorded highest macrobenthos density (21000 ind./m2), while station 5 recorded highest diversity (H’=2.19). Functional diversity (FD) for reproduction method was highest in station 1 (FD=0.61), ecological group in station 4 (FD=0.73); body shape (FD=0.56) and larval development (FD=0.63) in station 5, and lastly, adult mobility (FD=0.70) and feeding mode (FD=0.66) in station 6. Principal component analysis showed Station 1 has most modalities attributed towards it. Pearson correlation analysis suggested particle size distribution as major connector for most modalities (P=0.05). As BTA study is still new in Malaysian waters, it could serve as a good starting point for future assessment related to ecological functioning of benthic community in Malaysian seafloor. [ABSTRACT FROM AUTHOR]

An assessment of community of benthic macroinvertebrates in waters northwards of Pulau Indah, Klang was made with the main objective to determine distribution and diversity of benthic macroinvertebrates as well as to establish possible correlation between the community's distributions with environmental parameters. The sediments were obtained via Ponar Grab (0.023 m2 mouth area), followed by filtration (500 µm) and laboratory sorting in order to extract all specimens from sediments. The specimens were identified to the lowest taxonomic hierachy as possible. The physical parameters such as organic carbon (TOC) and grain size distributions were analysed. A total of 775 annelids, 15 arthropods, 12 echinoderms and 32 molluscs individuals were identified and recorded in six stations overall. Family Cirratulidae accounted to the highest numbers of the Annelids (n=358), whilst Cerithidae recorded as highest numbers of Molluscs. Station 5, 6 and 1 recorded the highest diversity index (H'=2.1845), evenness index (J'=0.6316) and richness index (Dmn=22.0454) respectively. Principal Component Analysis indicated sediment particle size as the major connector on all stations, with different station correlated to certain sizes of sediment particle. Pearson correlation analysis showed positive correlations between environmental parameters with eight benthic taxa in this study, with most correlations were on specific sediment particle size. As the study of benthic community is still inadequate in most of Malaysians waters, particularly in highly industrialised area such as waters in Port Klang, this study can serve as a starting point for any future studies concerning ecological disturbance affecting benthic community in Malaysian waters. [ABSTRACT FROM AUTHOR]

Horseshoe crab populations are declining worldwide, and Tachypleus tridentatus (Leach, 1819) has recently been classified as Endangered in the IUCN Redlist. Among the keys for species survival is successful reproduction. Although there are reports on the reproduction, particularly details on the spawning behaviour, of the American species, Limulus polyphemus (Linnaeus, 1758), information on Southeast Asia species is very scant. This field study reports the nesting activities of T. tridentatus at Jambongan Island, Sabah, Malaysia. Observation were carried out on 16 spawning pairs that were spotted during full and new moon from April-July 2016 in Sabah. Nest placements, number of nests, number of eggs, time spent at each nest, and nest widths, depth, and distance from the highest tide line were recorded for each pair. Tachypleus tridentatus generally laid an average of 967 ± 54.1 eggs/nest (171–2,282) in as many as nine nests on the intertidal zone between 125 and 940 cm from the highest tide. The first nest was dug once the tide began rising, followed by the consecutive nests towards the highest tide line with nest depths ranging between 13 and 22 cm. The complete spawning session (first nest to the last) ended in less than two hours. Time spent in spawning correlates positively with the number of nests and the total number of eggs laid by each spawning female. The spawning area, which is made up mainly by fine and medium-size sediment grains, also experience stable temperature, salinity, and dissolved oxygen conducive for egg-laying and larval development for successful reproduction. The details of spawning are important for planning successful future conservation initiatives for the species, especially in tropical regions. [ABSTRACT FROM AUTHOR]

Brachionus plicatilis is used to feed fish and crustacean larvae in the aquaculture industry. It is well established that the type of microalgae may influence rotifer production. This experiment was conducted to determine the effect of five different locally available microalgae species at Fisheries Research Institute (FRI), Kampung Pulau Sayak, Kedah, Malaysia on the instantaneous growth rate (μ) of rotifer. Nannochloris sp., Tetraselmis sp., Isochrysis sp., Chlorella sp., and Nannochloropsis sp. were used as feed at different algae densities (0.1, 0.3, 0.7 and 1.5 × 106 cells/ml) and culture volumes (20, 70 and 210 ml). At algae densities ranging from 0.3 to 1.5 × 106 cells/ml, an average μ value of more than 0.90 per day were recorded for all algae species. However, at density of 0.1 × 106 cells/ml, only Tetraselmis sp. resulted in the significantly highest μ value compared with others (p < 0.05). In terms of volume, smaller culture volume of Tetraselmis sp. (20 ml) showed significantly higher μ compared with higher volume (70 and 210 ml cultures). [ABSTRACT FROM AUTHOR]

In mangrove ecosystems, litter fall accumulates as refractory organic carbon on the sediment surface and creates anoxic sediment layers. Fiddler crabs, through their burrowing activity, translocate oxygen into the anoxic layers and promote aerobic respiration, iron reduction and nitrification. In this study, the effects of four species of fiddler crabs (Uca triangularis, Uca rosea, Uca forcipata and Uca paradussumieri) on organic content, water content, porosity, redox potential and solid phase iron pools of mangrove sediments were investigated. In each crab's habitat, six cores down to 30 cm depth were taken from burrowed and non-burrowed sampling plots. Redox potential and oxidized iron pools were highest in surface sediment, while porosity, water and organic content were higher in deeper sediment. Reduced iron (Fe (II)) and redox potential were significantly different between burrowed and non-burrowed plots. Crab burrows extend the oxidized surface layer down to 4 cm depth and through the oxidation effect, reduce the organic content of sediments. The effects of burrows varied between the four species based on their shore location. The oxidation effect of burrows enhance the decomposition rate and stimulate iron reduction, which are processes that are expected to play an important role in biogeochemical properties of mangrove sediments. [ABSTRACT FROM AUTHOR]

The article discusses a study on the embryonic and larval development stages of the dog conch or Strombus canarium in the laboratory. The Merambong Shoal in the Johor Straits in Malaysia was the source of egg masses. The long gelatinous tube of an egg strand produced by the species coiled and intertwined to form an egg mass. Embryonic development inside the capsule is said to be preceded by internal fertilization before the egg was spawned. The researchers conclude that larval development in the mollusk is similar to other Strombus species.