Seven species of freshwater crabs from three families are recorded from and around the Danum Valley Conservation Area in Sabah, Malaysian Borneo: Thelphusula capillodigitussp. n., Thelphusula dicerophilus Ng & Stuebing, 1990, Arachnothelphusa terrapes Ng, 1991, Terrathelphusa secula Ng & Tan, 2015, Parathelphusa valida Ng & Goh, 1987 (new record) (Gecarcinucidae); Isolapotamon ingeri Ng & Tan, 1998 (Potamidae); and Geosesarma danumense Ng, 2002 (Sesarmidae). The new species of Thelphusula Bott, 1979, can be distinguished from all congeners by a unique combination of morphological features, most notably the presence of dense patches of short setae on the fingers of the adult male chelipeds, as well as the structure of the male first gonopod. Arachnothelphusa terrapes is confirmed to be a phytotelm species. A key to all species in the conservation area is provided.
The aim of this work is to investigate the effect of exposure of heavy metals such as Ni, Fe and Mn on the growth of the cyanobacteria Anabaena flos-aquae, which can be found in fresh water environment. Results of the experiments showed that exposure of A. flos-aquae to Ni caused the most toxic effect as compared to exposure with Fe and Mn. The 96 hr LC50 value for Ni exposure was 0.321 mg/mL (approximately 30% inhibition), whereas Mn was the second most toxic metal followed by Fe with the 96 hr LC50 values of 0.684 mg/mL and 3.020 mg/mL respectively. This study demonstrated that even though Fe and Mn are essential micronutrients for A. flos-aquae, both show toxic effects at high concentrations. The difference in the toxicity value between Fe and Mn for A. flos-aquae is five times and this indicates that Mn was five times more toxic to A. flos-aquae than Fe suggesting that the Cyanobacteria is more tolerant to Fe when compared with Mn.
Groundwater is the prime source of freshwater in most small islands. A detailed groundwater and seawater chemistry study was undertaken from March 2006 to January 2007 to examine the evolution of groundwater in the shallow aquifer of Manukan Island, Sabah, Malaysia. Coastal groundwater aquifers especially for small islands are often exposed to heavy pumping and consequently to risks of seawater intrusion. Major ion chemistry analysis showed that the groundwater quality of the island experienced changes attributed to seawater intrusion. The groundwater has undergone a compositional change from Ca-rich to Na-rich which can be explained mostly by simple mixing process and cation exchange process. From the PHREEQC simulation model, calcite, dolomite and aragonite solubility showed positive mean values (0.65; 1.11; 0.51, respectively) of the saturation indices (SI) indicating supersaturation which attributed from the simple mixing and eventually cation exchange process. This information is important in protecting and remediating the disturbed aquifer situation.
The aims of this study are to isolate and characterize acid soluble collagen (ASC) and pepsin soluble collagen (PSC) extracted from silver catfish (Pangasius sp.) skin. Isolated ASC and PSC collagen were characterized in terms of chemical composition (moisture, protein, fat and ash content), protein concentration, functional group, solubility, and morphological properties as compared to commercial collagen. Yields of ASC and PSC were 4.27% and 2.27%, respectively. The chemical compositions of raw skin were 34.64%, 2.81%, 3.68%, and 0.31%, while the chemical compositions of ASC and PSC were 94.21%, 3.48%, 0.81%, 59.15%, and 88.25%, 3.46%, 0.92%, and 29.24%, for moisture, protein, fat, and ash, respectively. ASC and PSC had protein concentrations of 2.27 mg/mL and 2.70 mg/mL, respectively. Functional group analysis revealed that both isolated collagens exhibited Amide A, II and III as a fingerprint for collagen structure. The highest solubility was found at pH 4 for ASC, pH 1 for PSC, and pH 5 for commercial collagen. The morphology of the isolated collagens was porous and they contained fibril. In conclusion, the characteristics of the isolated ASC and PSC from silver catfish (Pangasius sp.) skin indicate that value-added collagen can be produced from the alternative source of freshwater fish.
Acute toxicity (96 h LC50) of phenol was analyzed in the cat fish Mystus vittatus in static bio-assay over a 96-h exposure period using probit method. The 24, 48, 72, and 96 h LC50 values (with 95% confidence limits) of phenol for fingerling catfish were found out as 13.98, 13.17, 12.62, and 12.21 mg/l respectively. Investigations pertaining to the histopathological sections have shown high degree of pathological lesions observed in various parts like gill, liver intestine, and kidney of the fish species. Analysis of gill section revealed observable changes in the experimental species such as fusion, malformation at the tip of secondary lamellae, vacuolation, hyperplasia, and epithelial damage. Exposure of phenol showed cytoplasmic vacuolation, tissue damage, and loss of hepatic cell wall in the liver of experimental organism. Lesions of tissue damage at the epithelial site, inflammation, and clumping of adjacent villi made of columnar epithelium have been observed in the intestine of fish, and also the excretory part of the fish kidney revealed various changes like glomerular atrophy, damage of Bowman's capsule, vacuolization, and degeneration of renal epithelium. The current study on histological changes observed in the experimental organisms has thrown light on the current scenario which poses threat and danger to the whole aquatic ecosystem, and this study plays a vital role in assessing the aquatic pollution.
The objective of this study was to assess the physico-chemical parameters and waterborne parasites in selected recreational lakes from Malaysia. Samples were collected from seven stations of Recreational Lake A (RL-A) and six stations of Recreational Lake B (RL-B). The samples were processed to detect the presence of Giardia spp. and Cryptosporidium spp. using immunomagnetic separation kit, helminth eggs or ova by bright field microscopy and Acanthamoeba spp. by cultivation in non-nutrient agar. Chemical parameters such as ammonia, chlorine, fluoride, nitrate and nitrite and physical parameters such as dissolved oxygen, electrical conductivity, pH, salinity, temperature and total dissolved solid were also measured. Both lakes were freshwater with salinity ranging from 0.05 to 0.09 ppt. Most stations of these lakes were contaminated with Cryptosporidium spp., Giardia spp., Ascaris spp. and hookworm. Schistosoma spp. was found in RL-B only, while Acanthamoeba spp. was found in all stations. Of all sampling sites, station 5 of RL-B is the most contaminated. Linear regression and correlation analysis revealed that Giardia spp. and Schistosoma spp. showed a significant negative correlation with turbidity (p water quality monitoring and to take appropriate safety measures to ensure maintenance of good water standards.
Nitrogen (N) transport from land to water is a dominant contributor of N in estuarine waters leading to eutrophication, harmful algal blooms, and hypoxia. Our objectives were to (1) investigate the composition of inorganic and organic N forms, (2) distinguish the sources and biogeochemical mechanisms of nitrate-N (NO3-N) transport using stable isotopes of NO3- and Bayesian mixing model, and (3) determine the dissolved organic N (DON) bioavailability using bioassays in a longitudinal gradient from freshwater to estuarine ecosystem located in the Tampa Bay, Florida, United States. We found that DON was the most dominant N form (mean: 64%, range: 46-83%) followed by particulate organic N (PON, mean: 22%, range: 14-37%), whereas inorganic N forms (NOx-N: 7%, NH4-N: 7%) were 14% of total N in freshwater and estuarine waters. Stable isotope data of NO3- revealed that nitrification was the main contributor (36.4%), followed by soil and organic N sources (25.5%), NO3- fertilizers (22.4%), and NH4+ fertilizers (15.7%). Bioassays showed that 14 to 65% of DON concentrations decreased after 5-days of incubation indicating utilization of DON by microbes in freshwater and estuarine waters. These results suggest that despite low proportion of inorganic N forms, the higher concentrations and bioavailability of DON can be a potential source of N for algae and bacteria leading to water quality degradation in the estuarine waters.
Toxic cyanobacteria blooms are increasing in magnitude and frequency worldwide. However, this issue has not been adequately addressed in Malaysia. Therefore, this study aims to better understand eutrophication levels, cyanobacteria diversity, and microcystin concentrations in ten Malaysian freshwater lakes. The results revealed that most lakes were eutrophic, with total phosphorus and total chlorophyll-a concentrations ranging from 15 to 4270 µg L(-1) and 1.1 to 903.1 µg L(-1), respectively. Cyanobacteria were detected in all lakes, and identified as Microcystis spp., Planktothrix spp., Phormidium spp., Oscillatoria spp., and Lyngbya spp. Microcystis spp. was the most commonly observed and most abundant cyanobacteria recorded. Semi-quantitative microcystin analysis indicated the presence of microcystin in all lakes. These findings illustrate the potential health risk of cyanobacteria in Malaysia freshwater lakes, thus magnifying the importance of cyanobacteria monitoring and management in Malaysian waterways.
Burkholderia pseudomallei causes melioidosis, a life-threatening infection in both humans and animals. Water is an important reservoir of the bacteria and may serve as a source of environmental contamination leading to infection. B. pseudomallei has an unusual ability to survive in water for a long period. This paper investigates physicochemical properties of water associated with the presence of B. pseudomallei in water supply in small ruminant farms in Peninsular Malaysia. Physicochemical properties of water samples taken from small ruminant farms that included temperature, pH, dissolved oxygen (DO2), optical density (OD), and chemical oxygen demand (COD) were measured after which the samples were cultured for B. pseudomallei. Multivariable logistic regression model revealed that slightly acidic water pH and higher COD level were significantly associated with the likelihood of the B. pseudomallei presence in the water.
A new species of semiterrestrial gecarcinucid freshwater crab, Terrathelphusa secula, is described from Danum Valley in Sabah, East Malaysia, eastern Borneo. In the form of its carapace, third maxilliped, and male second gonopod, it most closely resembles T. ovis Ng, 1997, and T. telur Ng, 1997, from eastern Sarawak and Brunei, respectively. It differs markedly from these and other congeners in its proportionately much wider carapace, and a male first gonopod that is strongly curved and sickle-shaped.
The complete mitochondrial genome of the enigmatic freshwater crayfish Engaeus lyelli was sequenced using the MiSeq Personal Sequencer (Illumina, San Diego, CA). The mitogenome has 16,027 bp consisting of 13 protein-coding genes, 2 ribosomal subunit genes, 23 transfer RNAs, and a non-coding AT-rich region. The base composition of E. lyelli is 29.01% for T, 27.13% for C, 31.43% for A, and 12.44% for G, with an AT bias of 60.44%. The species has the distinctive gene order characteristic of parastacid crayfish with the exception of some minor rearrangements involving the tRNA genes.
Seven polymorphic microsatellite loci were isolated and characterized for the snakehead murrel, Channa striata (Channidae), a valuable tropical freshwater fish species. Among 25 specimens collected from Kedah state in Malaysia, the number of alleles per locus ranged from 2 to 7. Observed and expected heterozygosities ranged from 0.120 to 0.880 and 0.117 to 0.698, respectively. A single locus (CS1-C07) was significantly deviated from Hardy-Weinberg equilibrium after Bonferroni correction. These novel markers would be useful for population genetic studies of the C. striata.
Eight single locus microsatellite markers were developed to characterize the Malaysian giant freshwater prawn, Macrobrachium rosenbergii. These microsatellites were isolated from an enriched genomic library contained by using a 5'-anchored polymerase chain reaction technique. Primers were designed to flank the repeat sequences and subsequently used to characterize 30 unrelated individuals of the giant freshwater prawn. The polymerase chain reaction amplification products of these eight microsatellite loci were polymorphic with the number of alleles ranging from two to 10 alleles per locus while the levels of heterozygosity ranged from 0.6333 to 0.8667.
The U.S. National Science Foundation-funded (DEB 1022720) 'All Cypriniformes Species Inventory' was initiated in 2010 and will be completed in 2015. It has accelerated the rate of discovery and description of cypriniform fishes, expanded our knowledge of the phylogenetic relationships of cypriniforms, increased the capacity for systematic research in other countries through student training and establishing long-term collaborations, including conferences in Thailand in 2012, Brunei in 2013, Burundi in 2013, and Malaysia in 2014, led to the formation of the Asian Society of Ichthyologists, and made available large numbers of specimens and tissues of freshwater fishes, including many species never before collected, in permanent collections in foreign and U.S. institutions.
A study of heavy metal contents in freshwater snails from rice fields have been made. The results indicate that the levels of heavy metals, Pb, Cu, Zn and Cd, are low and within the permissible limit of Malaysian Food Regulations. The results can serve as background data for further reference.
Southeast-Asian peat swamp forests have been significantly logged and converted to plantation. Recently, to mitigate land degradation and C losses, some areas have been left to regenerate. Understanding how such complex land use change affects greenhouse gas emissions is essential for modelling climate feedbacks and supporting land management decisions. We carried out field research in a Malaysian swamp forest and an oil palm plantation to understand how clear-felling, drainage, and illegal and authorized conversion to oil palm impacted the C cycle, and how the C cycle may change if such logging and conversion stopped. We found that both the swamp forest and the plantation emit centuries-old CO2 from their drainage systems in the managed areas, releasing sequestered C to the atmosphere. Oil palm plantations are an iconic symbol of tropical peatland degradation, but CO2 efflux from the recently-burnt, cleared swamp forest was as old as from the oil palm plantation. However, in the swamp forest site, where logging had ceased approximately 30 years ago, the age of the CO2 efflux was modern, indicating recovery of the system can occur. 14C dating of the C pool acted as a tracer of recovery as well as degradation and offers a new tool to assess efficacy of restoration management. Methane was present in many sites, and in higher concentrations in slow-flowing anoxic systems as degassing mechanisms are not strong. Methane loading in freshwaters is rarely considered, but this may be an important C pool in restored drainage channels and should be considered in C budgets and losses.
The Malaysian giant freshwater prawn, Macrobrachium rosenbergii, is an economically important crustacean worldwide. However, production of this prawn is facing a serious threat from Vibriosis disease caused by Vibrio species such as Vibrio parahaemolyticus. Unfortunately, the mechanisms involved in the immune response of this species to bacterial infection are not fully understood. We therefore used a high-throughput deep sequencing technology to investigate the transcriptome and comparative expression profiles of the hepatopancreas from this freshwater prawn infected with V. parahaemolyticus to gain an increased understanding of the molecular mechanisms underlying the species' immune response to this pathogenic bacteria.
Introduction: Collagen and gelatin are essential protein in vertebrates and extensively used in various industries. Methods: In this study, acid-solubilized collagen and gelatin were extracted from the scales of three different species of freshwater fish namely Kelah (Tombroides), Tilapia (Oreochromis niloticus) and Snakehead fish (Channidae) and then further quantified using Bradford assay and separated by molecular weight using SDS-PAGE. Results: The extracted collagen in Tilapia fish scale was found to be the highest with 0.018 of protein absorbance among the other three fish; Kelah fish (0.017) and Snakehead fish (0.011). For gelatin, Snakehead fish scales showed the highest amount of total protein concentration followed by Tilapia and Kelah fish with 0.467, 0.144 and 0.037 μg/μL per g, respectively. Based on the SDS-PAGE results, collagen from all the three freshwater fishes were identified as a type 1 (molecular weight approximately from 95 to 130 kDa) collagen. As for gelatin, only gelatin from Snakehead fish scale was identified to be a type 1(molecular weight approximately from 95 to 130 kDa) while the other two freshwater fishes showed no clear band due to high viscosity of the gelatin produced. Conclusion: It can be said that the fishes investigated in this study have a potential to be the alternative source of collagen and gelatin.
The taxonomy of the potamid freshwater crabs of the Johora tahanensis (Bott, 1966) species group (Potamoidea) is revised. Seven species are recognised, all from Peninsular Malaysia and southern Thailand, three of which are described as new. The three new species were previously identified as J. tahanensis but can be distinguished by characters of the carapace, male first gonopod, and vulva. A revised key to the 18 recognised species of Johora Bott, 1966, is provided.