Shipworms (family Teredinidae) are specialized bivalves that bore into the submerged wooden structures and mangrove trees, except genus Zachsia which is associated with seagrass rhizome. However, only one species has been described, located in Russian, Korean and Japanese waters and associated only with genera Phyllospadix and Zostera. Potentially wider distributions and even new species within this group have not been reported from another bioregion. Given the potential impacts on seagrass health, it is important to ascertain if the distribution of Zachsia extends across other climatic regions and seagrass species. In response, a study was conducted in a seagrass meadow at Gaya Island (Sabah, Malaysia). A total of 900 seagrass shoots were randomly excavated from a mixed seagrass bed of Enhalus acoroides, Cymodocea rotundata and C. serrulata. It was found that Zachsia sp. was present within the rhizomes of E. acoroides and C. rotundata, with an occupancy of around 12% occupancy (n=100) and 1% (n=400), respectively. A post-mortem examination indicated that the bivalve appeared to have ingested most of the rhizome’s internal tissues, leaving behind a calcareous hollow tube. Furthermore, this apparent infestation appeared to significantly reduce shoot growth by around 70% from 0.738±0.036 to 0.220±0.038 cm day-1. This finding may be significant, as it suggests, for the first time, that the rhizome parasitism is another possible vector in controlling seagrass growth and mortality. Further investigations are required to determine if this boring bivalve is indeed a new species, its distribution in other tropical areas and its role in the ecosystem.
Presence of metallic elements in organisms is one of the important topics in environmental pollution, toxicology and food safety. It has been extensively studied because of the impact of these elements on the ecosystem and health of the seafood consumers. This study provides information on the concentration of some essential metals (copper, Cu; zinc, Zn) and non-essential metals (cadmium, Cd; lead, Pb) in the commonly consumed marsh clam, Polymesoda expansa, sampled randomly from Tanjung Lumpur mangrove forest, Kuantan, Pahang. It also focuses on the human health risk assessment in terms of toxicity of these metallic elements. Closed acid digestion method was used to digest the samples and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) was used to measure the metal contents in the samples. The mean concentration of each metal in the tissues was recorded on a dry weight basis. The average values were: Cu, 15.5 μg/g.; Zn, 296 μg/g ; Pb, 2.31 μg/g and Cd, 1.04 μg/g . These values are within the permissible limits set by Malaysian Food Regulation (1985) and the World Health Organization (1982). The pollution load index (PLI) value of 2.94 indicates that there is no serious metal pollution in this study area. The correlation coefficient matrix between four metallic elements shows positive value, suggesting that the selected metals may have originated from the same source and accumulated in the clam tissue. A positive correlation was noted between the size of the clam and concentrations of Cd, Zn and Cu whereas it was negative for Pb. The present finding shows that the marsh clams from Tanjung Lumpur are safe for human consumption. However, a proper and continuous assessment should be done in order to monitor any changes in the contents of metallic elements since Tanjung Lumpur is near the Kuantan city center and the mining activities at the upstream area might at some stage cause metal pollution.
Sabah has extensive mangrove forests surrounded by oceanic waters which provide suitable habitat for many species of animals including mud crabs (Scylla spp.). This study was conducted to obtain information on the species composition, distribution and catch per unit effort in Marudu Bay, Sabah. Samplings were done monthly in five mangrove areas along the river channels in Marudu Bay (06°33’N; 114°44’E) from October 2012 to September 2013 using collapsible baited crab traps. From a total of 1859 mud crab specimens caught in Marudu Bay, three species were identified. Scylla tranquebarica was the dominant species forming 78% of the total followed by S. paramamosain 13% and S. olivacea 8%. The number of males (n=1224) was higher compared to females (n=635) with an average sex ratio male : female of 1.0:0.5. The catch per unit effort (CPUE) showed an average value of 0.55 trap-1 day-1 and revealed a declining trend throughout the sampling. S. tranquebarica was widely distributed in all the rivers surveyed, however, it mostly occurred in near the lower reaches of the river near the areas open to the sea where average water salinity ranged from 12.98 to 14.28 ppt and the environment favoured the growth of Rhizophora sp. Other species, S. paramamosain and S. olivacea, were mostly found in upstream areas covered generally by Nypa sp. and where average water salinity varied from 6.93 to 7.50 ppt. The information on the species composition, distribution and CPUE of the mud crabs in Marudu Bay can be useful for mud crab fisheries resources management in Sabah.
Particle size analysis is able to reveal essential information about processes like production, transportation, sorting, and deposition of a study area. Pre-treatment of sediment by using hydrogen peroxide is recommended for more accuracy of particle size distribution as it removes organic matter which is adsorbed on the grain particle. A shallow water where hydrothermal vents site are located in Guishan Island is selected as the study site in this research. Sediment samples were collected at the depth of 3 – 5 cm from the seabed surface by SCUBA diving. Particle size analysis was conducted by dry sieving before and after hydrogen peroxide treatment. Results showed significant differences in very coarse sand (p < 0.05) as it decreases significantly in weight after treatment (10.62% of change). The other particle size level of sediment increases slightly in weight and the changes ranged from 1.20% to 2.60%, showing no significant difference (500μm=0.59; p value 250μm=0.67; p value 125μm=0.48; p value 63μm=0.47; p value >63μm=0.38). Therefore, in order to accurately determine the particle size distribution at hydrothermal vent site, pre-treatment using hydrogen peroxide is recommended to remove organic material because hydrothermal vent is proved to have high organic matter content.
Microcosm experiments simulating the occurrence of early mortality syndrome/acute hepatopancreatic necrosis disease (EMS/AHPND) in white shrimp production ponds were performed in 30-L aquariums. Healthy white shrimp, Litopenaeus vannamei, were reared in aquariums containing EMS/AHPND-free hatchery or pond water. Raw pond sludge, collected from shrimp ponds where EMS/AHPND had occurred, was added to some test aquariums, while others were treated with sterilized pond sludge. In some aquariums, water pH was increased from 7.5 to 8.8. Microcosms with stable pH (around 7.5) and/or autoclaved sludge served as controls. The combination of raw sludge and increased pH induced EMS/AHPND and killed white shrimp, whereas raw sludge/stable pH and autoclaved sludge/increased pH combinations did not affect healthy shrimp. Thus, EMS/AHPND outbreaks are due not only to the causative agent but also to environmental stresses such as pH fluctuation. These findings contribute to improved management in shrimp production farms.
The present study describes the new record of Dicyathifer mannii under the family Teredinidae Rafinesque, 1815. Sampling was conducted in the mangrove area of Kuala Penyu and sample was collected from dead wood debris. The pallets of Dicyathifer is half-conical in shape and 8mm in length. The cone measured 3.9mm in length and 3.6mm in width. The cavity is 1.2mm deep; the curve of the opening on the cone is about 98% of the depth of the cone. Inside the cone cavity, from the center, a ridge with rib-like feature runs down the length of the cavity. Only one species of Dicyathifer is recorded and the present species is the first new record described in Malaysia with some additional measurement metrics for future taxonomic identification purposes.
The number of endangered coral species is increasing over the past decades due to multiple stresses and threats. Euphylliidae corals are among the species heavily targeted for the marine aquarium trade due to their colourful appearance and aesthetic importance. However, their distribution in Peninsular Malaysia has not been thoroughly investigated. Present study aims to investigate the diversity and abundance patterns of euphylliid species at 36 reef sites in Marine Protected Areas of Tioman, Redang and Payar Islands. Video transect surveyed a total of 671 euphylliids individuals belonging to six species from three genera. The diversity and evenness indices of euphylliids were significantly higher (P
Seagrass and mangroves support a number of ecosystem services, such as sustaining marine fisheries, water clarity, and the protection of shoreline from erosion. Producing a national and global consensus of their total worth is a challenge. More often than not the variety and distal evaluation approaches do not fit comfortably within current market-based economic models, which are arguably more capable of swaying government policy in assessing their preservation over economic development. The exception to this rule is the increasing recognition of the importance of these systems as a carbon sink for combating ‘greenhouse’ gas emissions. In response, these sinks have been labelled as ‘Blue Carbon, a rhetorical tool to distinguish them from terrestrial and ocean sinks, and the different approaches they would require for conservation. However, there are a number of knowledge gaps, untested underlying assumptions, and measurement practicalities in assessing an accurate value of carbon sequestration and storage. Unless these are addressed, then the push for seagrass and mangroves to be included within the carbon-financing network may not be successful. This short communication discusses the limitations of the current blue carbon conceptual model, and provides recommendations for a more limited but robust submission of its present and future worth, required for carbon financing.
Selingan Island off Sandakan, Sabah is a famous turtle nesting ground and a part of the Turtle Islands Park (TIP) within the Coral Triangle region of Malaysia. This small island faces the serious problem of beach erosion that is reducing the turtle nesting area. Sabah Parks deployed stone revetments in 2005, followed by placement of reef balls at the southern part of the Selingan Island in 2007 for protecting the shoreline. The objective of this study was to determine the effectiveness of these measures for shoreline protection. Shoreline changes were determined from satellite images, beach profiling and field observations. Satellite images from 2010 to 2016 were obtained from Google Earth Pro analyzed to examine the changes in the shape and size of the island with QGIS software. Beach profiling was performed in December 2017 at three sites and compared with the condition in 2011. The findings indicated that the shape of the island was squeezed towards the east where the reef balls were located. The size of the island has not changed much in 9 years after the deployment of the reef balls, but a high volume of sediments accumulated at the south due to the presence of shoreline protection. Generally, the man-made structures in Selingan Island are effective in trapping the sediment and providing more nesting area for turtles. It is recommended that the shoreline dynamics of the island should be regularly monitored for better understanding of the changes and taking appropriate actions.
This study was conducted to determine the taste preference of hybrid grouper (Epinephelus fuscoguttatus × Epinephelus lanceolatus) for nucleoside (inosine - INO) and nucleotides (inosine-5’-monophosphate – IMP and guanosine-5’- monophosphate - GMP), which are commonly used as feeding stimulants in fish diets. Behavioural assay was conducted by feeding the fish with the agar gel pellets that contained the taste substances and observing their feeding response through
video recording. Preference Index (PrfInd; minimum = 0, maximum = 1) was calculated to evaluate the fish preference for the taste substances tested. Data so collected suggested that INO, IMP, and GMP were generally preferable by the hybrid grouper. However, INO was the most potential FS for both S and L sizes (19.7 ± 1.4 g and 162.3 ± 50.5 g in BW, mean ± S.D.) hybrid grouper based on its functional dosage. In the S size fish, INO attained high PrfInd at both 0.1% and 1% (0.84 and 1) concentration levels, while IMP and GMP attained high PrfInd at 1% (both 1) but low PrfInd (0.6 and 0.13,respectively) at 0.1%. In the L size fish, INO also attained very high PrfInd at 0.01% (0.87) but IMP and GMP were not (0.13 and 0). In addition, improvement in the taste acceptance to INO of the hybrid grouper was evident in this study. The S size fish rejected INO at 0.01% (PrfInd = 0) but the L size fish accepted it very well (0.87). These results suggested that the supplementation level of INO in the practical diets for the hybrid grouper can be decreased with the fish growth during the grow-out period.
Stratified estuaries are home to expanding aquaculture activities whose ecological footprints can be observed through trends in microbial community respiration in the water column. Bottle incubations are widely used to measure water column community respiration in marine and freshwater ecosystems by measuring the flux of dissolved oxygen occurring in the bottle over a period of time. When in situ dissolved oxygen (DO) concentrations are markedly different than DO concentration of the incubation medium the potential for diffusion of oxygen across the bottle opening is great and may be especially pronounced in strongly stratified systems with relatively low rates of pelagic oxygen consumption. We incubated 60 Biochemical Oxygen Demand (BOD) bottles filled with sterilized water with DO concentrations ranging from 2.51 mg O2 L-1 to 10.03 mg O2 L-1 for 24 hours in a temperature controlled water bath. There was a significant relationship when DO flux was set as a function of initial DO (DO Flux = -0.0017x + 0.0085, r2 = 0.72, p < 2.2 e-16). DO fluxes ranged from -0.012 mg O2 L-1 hour-1 to 0.005 mg O2 L-1 hour-1 for bottles incubated with initial DO ranging from 10.03 mg O2 L-1 to 3.31 mg O2 L-1, respectively. These results suggest that diffusion across the ground glass seal of BOD bottles is possible and that extra precaution through parallel diffusion controls should be considered when measuring pelagic respiration using BOD bottle incubations in systems with relatively low or relatively high in situ DO concentrations.
A 25-week feeding trial was conducted to assess the growth performance, organoleptic quality, and to estimate the viability of nourishing hybrid grouper (Epinephelus fuscoguttatus x Epinephelus lanceolatus) with low-cost fish (LCF) and commercially compound feed (CCF). A group of 3600 juvenile fish (182g) were released in four sea cages and fed with either LCF or CCF in duplicate. At the end of the trial, the hybrid grouper provided LCF attained a significantly higher (P0.05). Although technicalities of fish fed with LCF suggest that LCF is more efficient than CCF, feeding LCF to high-value fish is an unsustainable practice as LCF is usually obtained through trawling – a destructive fishing method for the marine ecosystem. Therefore, feeding with CCF without the use of LCF as the source of protein for its fishmeal will contribute to sustainable aquaculture. In order to convince the local farmers in Sabah to adopt the practice of feeding CCF, future research should focus on completing the species-specific diet formulation to promote optimum growth, and find ways to reduce the CCF local selling price.
Combining feeding appendage morphology and behavioural observation of the motion pattern of the feeding appendages clarified many aspects underlying the feeding processes of the giant freshwater prawn (Macrobrachium rosenbergii) and the marine whiteleg shrimp (Litopenaeus vannamei) in aquaria. The food intake behaviour was video recorded during eating pellet food, and pieces of fresh squid and fish. While M. rosenbergiitook pellet one by one, L. vannamei picked up many pellets at one time and held them at the mouth with the 3rd maxilliped endopods and the 1st walking legs. Both species used the right chelate walking legs rather than the left walking legs to pick up the food. The 3rd walking legs of L. vannameiwere longest and heaviest among the chelate walking legs but their major role was not for feeding but for feeding contests often in the form of aggression. While M. rosenbergii easily crunched pellets by the mandibles, L. vannamei did not crunch pellets due to the softer and not so strong mandibles and frequently spat out them, indicating that the present hard pellets are not suitable for L. vannamei. Both the species kept a piece of elastic fresh squid or fish flesh at the mouth and tore the food into small pieces with the help of repeated pulling down motion of the 3rd maxilliped endopods. However, the mandible teeth of the two spices were not sharp enough to gnaw off the fibrous muscle in one bite. The 2nd and 3rd maxilliped endopods were used for holding food at the mouth and did not contribute to mastication of food. The 2nd and 3rd maxilliped exopods exhibited the horizontal fanning motion, which caused a unidirectional water flow moving backwards in the gill chamber (visualized with milk). The maxilliped exopods were found to contribute not to feeding but ventilation. Based on the results obtained, development of softer pellets was recommended for L. vannamei.
The previous behavioural studies on vision of decapod crustaceans were often based on the assumption that the visual field of the test animals was all around and there was little or no blind area above or to the rear of the animals. In the present study, we determined the visual field of the wild captured purple mud crab (Scylla tranquebarica) and the farmed whiteleg shrimp (Litopenaeus vannamei) by eliminating the directions in which vision is anatomically blocked in all directions around the eyes. The mud crab had the visual field covering the entire visual world except for the ventral-most blind area. The whiteleg shrimp has the visual filed with a 66˚ binocular field and can see all around but is morphologically blocked by the scaphocerite extended forward between the eyes. While the transparent scaphocerites transmit 80 % of light from 400 to 700 nm wavelengths, an object seen through the scaphocerites is faded due to the light refraction, indicating that the morphological blocking is not always negligible. The trait of these visual fields should be taken into consideration in the design of visual behaviour experiments.
Feeding attractiveness of 21 fresh herbs was examined for the giant freshwater prawn (Macrobrachium rosenbergii) and the whiteleg shrimp (Litopenaeus vannamei) at different growth stages in tanks. The feeding attractant and enhancement were assessed by behavioural observations of the test animals in response to pelleted feeds incorporated with the herbal extracts in different concentrations. For M. rosenbergii, peppermint (Mentha piperita) and dokudami (Houttuynia cordata) were the most attractive herbs at all stages, and garlic (Allium sativum) strongly attracting to the juveniles but only weekly to the adults, postlarvae and larvae. Peppermint significantly enhanced feeding of M. rosenbergii at all stages except for the larvae. Garlic was a significant feeding enhancer for M. rosenbergii juveniles and postlarvae. The inclusion of the herbal extract at high concentrations had a negative effect on the feeding. As far as L. vannamei is concerned, the red chilli (Capsicum annuum) was the best feeding attractant and ginger (Zingiber officinale) and peppermint were moderate attractants for adults and juveniles. While galangal (Alpinia galangal), ginger and yellow onion (Allium cepa sp.) enhanced feeding in L. vannamei adults, but red chilli, garlic and peppermint did not enhance feeding. Evidently, the strong feeding attractants were not necessarily effective feeding enhancers. The incorporation of several herb extracts at higher concentrations caused a negative effect on the feeding of the test animals. This could be due to the presence of feeding deterrents in the herb such as saponins which are known to lower food palatability in insect, decapod crustaceans and fishes. More long-term work is warranted to determine if inclusion of feeding enhancing herbs in artificial feed promotes growth performance of the shrimp.
Sponges are major source of numerous cytotoxic compounds that are used for defence as well as adaptation to the environment. Numerous studies have discovered compounds from sponge extracts that were effective against a wide range of cancer cells. In this study, a total of 23 sponges comprising of 19 species were collected from Northeast Borneo. Sponges were treated and extracted using modified Folch extraction method, followed by cytotoxicity assay to determine their effectiveness against different colorectal cancer cells. Our results demonstrate that Monanchora clathrata, Dysidea sp., and Jaspis sp. possess different degrees of cytotoxicity against a wide range of human colorectal cancer cells. Monanchora clathrata (KDT07), Dysidea sp. (KDT09), and Jaspis sp. (KDT18) are among the demosponges which possess significant cytotoxicity against colorectal cancer cell lines, including HCT116, LoVo, SW480, and SW620. KDT08 and KDT21 which fall under the same genus Dysidea, possess insignificant cytotoxicity against colorectal cancer cells suggested environmental factors (symbiotic organisms) play a role in biosynthesizing bioactive compounds. Presented results suggested the importance of intensifying research on isolating and purifying natural products from marine sponges for useful applications.
Magnetic water is produced when water is passed through a magnetic field with the purpose of modifying its structure. The
changes in physical and chemical properties of magnetised water affect the biological properties of the organisms. The
magnetic field can affect the growth of fish from the embryo to the adult stage. The present study evaluates the effects of
magnetic field exposure on water properties and hatchability of the eggs of African catfish (Clarias gariepinus). Water was
passed through magnetic devices of different intensities; namely: 0.10, 0.15 and 0.20 Tesla. The dissolved oxygen (mgL-1) and
pH levels were found to significantly (P ≤ 0.05) increase from 5.92 mgL-1 to 6.33 mgL-1, and from 8.03 to 8.19, respectively.
Ammonium (NH4-N mgL-1) level declined significantly (P ≤ 0.05) (0.20 mgL-1 to 0.16 mgL-1). Salinity (ppt), conductivity (uscm1), specific conductance (uscm-1) and total dissolved solids (mgL-1) also decreased after magnetization. Significant increase in
the rate of hatching was attained in water exposed to a magnetic field of 0.10, 0.15 and 0.20 T. The study demonstrated the
benefits of using magnetic devices that are simple, practical and cost-effective.
Shrimp aquaculture has great potential for providing income and employment opportunities to farmers. Shrimp production can also contribute to economic growth given its high value and demand in Malaysia. However, it is often said that players in the marketing channel extract high margins for themselves. This study intends to verify this claim by examining a case study based on white leg shrimp (Litopenaeus vannamei) aquaculture in Kedah. The data for this study was obtained from a detailed study involving a shrimp retailer in Kedah. The marketing margins were calculated from the interviews of the farmer and the retailer. The results showed that the marketing channel was quite efficient because there was no large gap in the prices between the marketing channels. The difference between retail price and farm price is only RM7 per kilogram for the white shrimp which accounts for 43.75 percent of total farm price and represents the cost of bringing shrimps from the farm to the retail market.
Food related disease or food poisoning is prevalent worldwide and is associated with high mortality. It can be caused by bacteria, viruses, parasites, enterotoxins, mycotoxins, chemicals, histamine poisoning (scombroid) ciguatera and harmful algal bloom (HAB). Illness can also result by red tide while breathing in the aerosolized brevitoxins (i.e. PbTx or Ptychodiscus toxins). Bacterial toxin food poisoning can affect within 1-6 hours and 8-16 hours, and illness can be with or without bloody diarrhea. The common symptoms of food poisoning include abdominal cramps, vomiting and diarrhea. Diagnosis includes examination of leftover food, food preparation environment, food handlers, feces, vomitus, serum and blood. Treatment involves oral rehydration, antiemetic, and anti-peristaltic drugs. Antimicrobial agents may be needed in the treatment of shigellosis, cholera, lifesaving invasive salmonellosis and typhoid fever. Proper care in handling and cooking is important to prevent any food borne diseases.
We hypothesized that fish with red-sensitive retina would be stressed by red light and thus inhibited in somatic growth. Red sea bream (Pagrus major) juveniles (total length =3 cm) with red-sensitive retina were chosen to test this hypothesis. We examined the effect of different color lights (red with λmax 605 nm; green with λmax 540 nm; blue with λmax at 435 nm; and white with full spectrum) on unfed juveniles in laboratory tanks. Stress level was measured by the plasma cortisol and glucose concentrations, and nutritional status by muscle RNA/DNA ratio. Under red light, plasma cortisol and glucose, and muscle RNA/DNA were significantly higher than under green, blue, or white light. Our hypothesis was partly supported by previous findings on the effects of the color environment and spectral sensitivity of reared fishes. However, the levels of cortisol, glucose, and RNA/DNA in this study were low compared to published values. It seems that hatchery-bred juvenile red sea bream have adapted to red-rich surface light and are able to cope with the stress of living in surface floating cages which is so different from their deep-water habitats.