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.
There is a paucity of information on the global distribution and capture fisheries of the spiny lobster Panulirus, spp. Under the IUCN Red List produced by the International Union for Conservation of Nature that acts as a critical indicator of the health of the world’s biodiversity, most of the Panulirus spp. are categorized under least concern category while some show a declining trend. Further investigations are needed due to data deficiency. The present survey was carried out in the western region of Labuan island. Seven random stations along the west coast of the Island were selected for observations during day dive. Generally, the density of the spiny lobsters was low throughout the present study. Only four individuals of two spiny lobster species were recorded. Two individuals of P. versicolor were observed in station 2 while the other two (P. ornatus) were spotted in station 4. This low number could be due to the preliminary nature and limited duration of the study. Spiny lobsters tend to have a wide range of depth preferences. Two adult specimens of P. versicolor were spotted in an environment where turbidity was low. Further investigations over extended period of time and covering larger sampling areas will be necessary to accurately establish the habitat preferences and other ecological aspects of P. ornatus and P. versicolor.
Despite many good policies and institutions, the coastal environment of Langkawi continues to deteriorate. This could be due to lack of effective governance as well as unregulated waste discharge. Evidences collected from the literature during 1996 to 2013 also revealed a significant increase in the concentrations of Zn (R2 = 0.78) and Pb (R2 = 0.12) in the sediment. This appears to be the result of large volume of terrestrial runoff that brings these metals originating from extensive anthropogenic activities. It is a vital indicator of coastal pollution. It is a matter of concern that in many cases Pb concentration in the sediment exceeded the world average value 20 μg/g as well as Canadian Interim Sediment Quality Standard of 35 μg/g for the coastal areas. Similarly, the metal pollution index (MPI) measured over a period of 2007 to 2009 in fish also indicated an increasing trend of pollution in Langkawi. The maximum MPI value (4.87) was recorded in Spanish mackerel. Since pollution of coastal environment has serious implications for marine biodiversity and health of seafood consumers, measures are required to address this problem. Use of constructed wetland might be effective in reducing the coastal pollution as this will filter the effluent and waste before their mixing with the coastal water. Furthermore, enabling the stakeholders to play the environmental stewardship role will ensure better governance of coastal ecosystem and effective implementation of policies, envisaging an improved monitoring of waste/effluent discharge into the coastal marine environment. These measures are among the actions necessary for achieving a sustainable coastal environment of Langkawi.
Biodynamics of water quality and related issues in integrated aquatic farming systems, especially the Integrated Multi-Trophic Aquaculture (IMTA), are reviewed in this paper. Combining several species in one system in addition to the microbiological organisms that become part of a production unit achieve biodynamics that is truly remarkable and mimics the processes that nature utilizes through biodiversity and interlinkages. Nutrient cascading is the most visible process in such a system. Some of the features that characterize IMTA include: harmonious functioning of multiple species, self-manuring, in tune with nature, wellbeing of captive stocks and low-carbon processes. Basically, IMTA has three loops: fed species and biofiltration, and the water quality impacted by processes in the first two loops. Maintaining homoeostasis in the system can be challenging for a number of reasons, including species-specific water quality requirements, turnover of dissolved gases (mainly oxygen and nitrogen) and particulate matter. Ammonia fluctuates with pH and temperature. Dissolved oxygen is influenced by temperature. While at neutral pH (7.0), more than 95% of ammonia is in ionized, non-toxic form (NH4+), the percentage of toxic un-ionized ammonia (NH3) increases with pH at a given temperature. NH3 is highly toxic. It produces stress at 0.1 mg/L by damaging the gills and disrupting metabolism, and death at higher concentrations. Nitrite is toxic when its concentration exceeds 0.4 mg/L. Concentration lower than this value can be fatal for more sensitive species. Process of nitrification that converts ammonia to nitrite and nitrite to nitrate requires at least 6 mg/L of dissolved oxygen. The culture system should remain well aerated, at slightly alkaline pH and moderately warm temperature, and must have substrate for nitrifying bacteria. Roles of the various types of filtering devices for organic and inorganic wastes are discussed in this paper.
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 central and north west coast of Sabah lies along the western extremity of the Coral Triangle, within which are situated several marine protected areas (MPAs). In the present study we determined in situ coral reef fish populations in several localities along the west coast of Sabah, by exploring species abundance, richness and diversity of ten economically important fish species. The underwater surveys were conducted from May to December 2015. During this eight- month period, surveys at each site were undertaken once every two months. Dives were conducted during the daylight hours. A total of 171 individuals from the targeted fish species were enumerated from the 349 still images and 220 minutes of video footage. Abundance was observed mainly in the semi-protected MPA (n=110) with only one fish species recorded with more than 2 individuals at protected MPA and unprotected sites. We observed a correlation between fish species richness and coral topographic complexity, with study sites at the semi-protected MPA having the most complex topography landscape, and accordingly recording the highest Shannon-Wiener index (H= 2.85). Higher abundance recorded at study sites in the unprotected sites and semi-protected MPA indicate that such areas could potentially become de facto MPAs. A long-term monitoring, assessment and evaluation of the multiple degrees of variables involved such as length-weight relationship, type of habitat, variation in depth, and species behaviour are recommended in order to understand better the relationship and dynamics between these variables.
While the olfactory cue hypothesis has been proposed for spawning migration of silver eels, it has been shown that olfactory cells and associated mucus cells degenerate in male and female eels after hormonally induced sexual maturation. However, the degeneration of the olfactory organ could be a real event in the sequence of maturation, or may be an unnatural side effect of the hormone treatment itself. We morphologically and histologically examined the olfactory rosettes of hormone-untreated and hormone-treated (mixture of hCG and PG) giant mottled eel (Anguilla marmorata) and Japanese eel (A. japonica). The olfactory rosette from all the hormone-treated specimens significantly degenerated at various degeneration levels even in sexually immature specimens, indicating the side effect of the hormone-treatment. However, a sexually immature non-hormone treated female A. marmorata (87.4 cm TL, 199.4 g BW, at less advanced maturity) had slightly degenerated olfactory rosette. Further studies should focus on conducting natural degeneration of the olfactory rosette during the sexual maturation in tropical eels.
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.
The mangrove red snapper, Lutjanus argentimaculatus is a prized food-fish in the tropical and subtropical fisheries, as well as the aquaculture industry. This study investigated the distribution of L. argentimaculatus at three patch reefs of Lankayan Island, within the Sugud Islands Marine Conservation Area. Fish surveys were conducted 12 times at each of the selected patch reefs, from August 2016 until March 2017. Underwater video footages, hydrodynamic parameters (current direction and current speed) were recorded during each survey. The distribution patterns of the fish were plotted against these parameters to determine any correlation, in response to these parameters. There was a significant relationship between the current direction and the position of red mangrove snapper at the reef where schoolings were found to occur. We found that regardless of the current speed, the schools of red mangrove snapper were always present at the reef slope facing the oncoming current. This finding is important for the management and conservation of this species, which is a targeted species in the Live Reef Food Fish Trade (LRFFT), and is useful for the management of a Marine Protected Area (MPA) in general. This finding is also important as it provides useful insights into the ecology of mangrove red snapper.
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.
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.
The present study was aimed at evaluating the reproductive performance of the broodstock of purple mangrove crab (Scylla tranquebarica) fed natural food and formulated diets supplemented with astaxanthin and/or DHA. Formulated diets were supplemented with 500 mg kg-1 of astaxanthin (FA), 10 g kg-1 of DHA (FD) and both astaxanthin and DHA (FA+D). Diet without astaxanthin and DHA (FCon) and natural food (NF) consisted of forage fish (Valamugil sp.), shrimp (Penaeid sp.) and mangrove clam (Polymesoda sp.) to serve as control. Female broodstock of initial body weight 129.07±17.03 g were stocked in HDPE tank and cultured under recirculating water system. Broodstock maturation was monitored until spawning. Reproductive performance of female and condition of the larvae were also evaluated. After 50 weeks, broodstock fed FA+D diet showed better maturation percentage, spawning rate, gonadosomatic index, oocytes diameter, molting, molt death syndrome and survival rate than FCon group (P0.05) to the FA+D group but diet FD resulted in better performance than FA. Broodstock fed FA+D diet had the highest hatching rate, number of larvae produced and significantly higher zoea II survival compared to FCon and NF groups (P
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.
This study was aimed at determining the optimum temperature for culturing the copepod, Euterpina acutifrons. The trial was conducted for 10 days in chambers at temperatures of 25⁰C, 27⁰C, 29⁰C and 31⁰C. Ten adult individuals of the copepod were randomly collected and placed into three replicate experimental flasks for each treatment. Throughout the trial, the salinity, light intensity, and photoperiod were maintained at 30 ±2psu, 100molm-2s-1 and 12:12 light-dark cycle, respectively. The copepods were fed with 80,000cell/ml Isochrysis sp. daily. At the end of the trial, the total numbers of E. acutifrons nauplii, copepodites and adults were determined and counted using Sedgwick-Rafter. The highest population was found at 27⁰C with mean total population of 800±100 individuals from an initial of 10 individuals. This was followed by those reared at 25⁰C and 29⁰C where the population counts were 700±100 individuals and 367±115 individuals, respectively. At the 31⁰C, all the copepod specimens were found dead on day 5th. Statistical analysis showed that the temperature had a significant effect (P
This study was conducted to investigate the effects of dietary inclusion of Spirulina platensis on growth performance and hematological parameters of juvenile Asian sea bass (Lates calcarifer) reared in a freshwater culture system. Five experimental diets were prepared by replacing fish meal protein with the microalga at replacement levels of 5% (SP5), 10% (SP10), 20% (SP20) and 30% (SP30), and the substitution effect was compared with a control diet (Con) in which fish meal was the sole protein. Fish were stocked in net cages placed in a 150-ton tank with a stocking density of 20 fish per cage. After 8 weeks of feeding trial, the fish did not show any significant differences in growth performance but numerically higher weight gain and specific growth rate were achieved in the fish stock fed diet SP10 compared to other treatments. Feed conversion ratio and survival rate of fish were significantly affected by the inclusion of Spirulina in the diets. Except for crude ash content, whole-body proximate composition of the experimental fish was also significantly influenced by the diets. Regarding the effects of diets on blood parameters, only hematocrit, hemaglobin, HDL-c and AST were significantly affected by the inclusion of Spirulina in the diets. This study demonstrated that Spirulina could replace up to 10% of FM protein in practical diets of juvenile Asian sea bass without negative effects on growth performance. However, replacement of fish meal with Spirulina meal at 5% might be considered for commercial use considering a significant decrease in survival above this value.
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.
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 present study was aimed at evaluating the growth performance and feed utilization of marble goby (Oxyeleotris marmorata) juveniles fed with the acidified diets (AD). In feeding trial I, five fish meal-based diets were prepared [control (pH 6.0), AD 5.3, 4.3, 3.2 and 2.5]. Each diet was fed to triplicate batches of wild-caught O. marmorata (19 fish/ tank; total length, TL = 4.72±0.46 cm) for 8 weeks. The control, AD 5.3, and AD 4.3 treatments were terminated at week 4, due to drastic decline in total feed intake (TFI=0–0.05 g) and weight loss (weight gain, WG = -15.3 to -16.9%) in the fish. The AD 3.2 and AD 2.5 treatments were continued until week 8. Fish fed with the AD 3.2 showed significantly higher (P < 0.05) TFI (0.98 g) compared to those fed with the AD 2.5 (0.73 g) at the end of the trial. Feeding trial II was done to assess the long-term effects of AD for another 7 weeks. Thirty fish specimens were randomly selected from each of AD 3.2 and AD 2.5 treatments and stocked individually in 7 L aquaria to eliminate the territorial behaviour that was observed in the first trial. At the end of the experiment, fish fed AD 3.2 attained significantly higher (P < 0.05) WG (34%) than those fed AD 2.5 (13%). However, the growth performance and feed utilization results of the present study were very poor compared to those fed the normal fishmeal-based diet as is evident from synthesis of data from the literature review. Feeding of acidified diets was, therefore, not recommended for an extended period (> 3 weeks). Nevertheless, based on the strong preference of the fish for AD, it is worth trying to develop a weaning protocol using these diets as the starter feed and then slowly replacing them with the normal diet.
Bivalves are known for their ability to accumulate contaminants such as heavy metals. This allows them to be widely used as bioindicator in monitoring of heavy metals in the marine environment. This study was conducted to determine the levels of heavy metals, namely Copper (Cu), Chromium (Cr), Nickel (Ni), Lead (Pb), Arsenic (As), Zinc (Zn) and Manganese (Mn) in marsh clams (Polymesoda expansa) and green mussels (Perna viridis) along the northwest coast of Sabah (Marudu Bay, Ambong Bay, and Mengkabong). The results showed that As (5.1 to 12.8 μg/g) and Mn (33.5 to 116.0 μg/g) concentrations in both marsh clams and green mussels collected from all the sampling stations along the northwest coast of Sabah were much higher than the permissible limit set by the Ministry of Health Malaysia and FAO/ WHO. Similarly, concentration of Zn (265.8 to 535.9 μg/g) in marsh clams from all the sampling areas and that of Cr (53.9 μg/g) in green mussel collected from Marudu Bay were also much higher than the permissible limits. The data also suggested that marsh clams accumulated higher Pb and Zn, whereas green mussels tend to contain higher concentrations of Cr, Cu and Ni. Since bivalves are an important protein source for the local population, a regular monitoring of all edible bivalve species should be conducted so that consumers can be advised about the toxicological and health risks due to consumption of bivalves.
Tieshangang Bay in the Beibu Gulf, Guangxi of China, is a strategic location for pearl farming. Although water pollution has been reported in this bay but the general health of the pearl oyster, Pinctada fucata martensii, farmed there has never been assessed. The present study examined the condition of P. fucata martensii farmed in the Tieshangang Bay by analyzing its length-weight relationship (LWR) and relative condition factor (RCF). A total of 111 specimens were sampled for measuring their shell height and total weight for determining the LWR and RCF. The coefficient of correlation of the LWR was high (R2 = 0.93), significant at 0.01 level. Negative allometric growth (b = 2.7048) was observed. However, P. fucata martensii achieved the expected growth in terms of weight, as determined through the RCF (mean 1.13). Negative allometric growth is commonly reported on the wild Pinctada spp. collected from different regions. Apparently, the water pollution in the Tieshangang Bay did not compromise the general health of the pearl oyster cultured there. Nevertheless, further study on the farm’s surrounding water quality and plankton availability is necessary to investigate the interaction between the growth of the oyster and its culture environment. In conclusion, the P. fucata martensii farmed in the Tieshangang Bay was considered healthy and the bay is still suitable for pearl oyster farming.