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.
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
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
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.
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.
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.
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.
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.
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.
Aquaculture has emerged as an important sector for addressing the challenge of global food security. In order for it to play this role, certain supporting policies and mechanisms are necessary. Because aquaculture is a subject where there is a convergence of science, art and business, this has a better chance of knowledge-based entrepreneurship. With the demand of seafood steadily rising, the market potential is high to strengthen the business activity related to aquaculture. Aquaculture can be conducted in a wide variety of aquatic environments, whether on land or in the sea, using different methods to produce many kinds of plants and animals for human consumption. This sort of diversity offers entrepreneurship of different types and scales. Not many subjects have as much advantages for entrepreneurship as aquaculture. Government demands that universities in Malaysia should impart entrepreneurship education to students and researchers to commercialize their findings. Aquaculture is one of the niche areas of Universiti Malaysia Sabah (UMS) and thus, it becomes a priority to implement the national policies pertaining to this sector. Steps taken by the University to demonstrate our response through specific case studies are explained in this paper. Borneo Marine Research Institute developed aquaculture as its flagship program of education and research. This included building of infrastructure and expertise. UMS is the only university in the country with two on-campus hatcheries (for finfish and shellfish) to offer education, training and research. Entrepreneurship is an integral part of the undergraduate program. Worthwhile research carried out yielded results of great significance in promoting aquaculture industry. Selection of need-based research topics and problem-solving approaches applied to produce tangible outcomes are highlighted here. The paper also elaborates what it takes to be an aquaculture entrepreneur and constraints of applying industrial model of aquaculture under the academic culture of institutions of higher education. It is evident from an in-depth analysis of the scenario that academic entrepreneurship requires a radical departure from the past practices and a paradigm shift to successfully unify the art, science and business of aquaculture to achieve seafood sustainability and security.
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.
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.
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.
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.
Stocking density can induce stress in fish in an aquaculture system if not handled properly, and the chronic stress may lead to mortality. Several studies have reported that the capability to deal with a range of stocking densities differs among fish species and maturity stage. Hence, fish larvae may have different resilience to stress from the adult fish. Milkfish larvae were reared in hatchery for 50 days using a recirculating culture system at four different stocking densities (8,12,16 and 20 larvae/liter). The growth performance was not significantly different (P>0.05) except at stocking density of 20 larvae/liter. The highest survival rate (88.04%) was recorded in the system with 8 larvae/liter while the lowest (55.44%) in the culture tank where stocking rate was 20 larvae/liter. The stocking density also influenced the RNA / DNA ratio of the milkfish larvae. The RNA/DNA ratio showed a pattern that was identical with that of sigmoid growth where stocking rate of 8, 12, and 16 larvae/liter gained weight until 30 days of rearing. Highest RNA/DNA ratio was recorded at 16 larvae/liter (2.85±0.004), while the lowest was at 20 larvae/liter (2.25±0.217). Food availability might play a limiting factor that leads to the lower RNA/DNA ratio of larvae reared at a high density due to competition.
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.
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.