Influence of lunar cycle, moon driven tides and water physicochemical factors on the gonadal maturation of green mussel, Perna viridis, in the inner Malampaya sound, Taytay, Palawan, Philippines

This study determined the influence of the lunar cycle, tidal fluctuation, as well as water physicochemical factors on the gonadal maturation of green mussel, Perna viridis, in Malampaya Sound, Taytay, Palawan, Philippines. Monitoring and sampling were conducted for the 6 months, from October 2017 to March 2018. It was observed that the lunar cycle has a direct influence on gonadal maturity. Gonadal changes in both male and female P. viridis were observed histologically and both exhibit the characteristic of lunar-synchronous pattern.  It was observed that a high number of green mussels with spawning stages usually occur during the full moon and new moon. Furthermore, gonadal maturity was also affected by the tidal fluctuation. A higher number of P. viridis with spawning stages were recorded during spring tide, whereas the percentage of spent individuals were higher during neap tides. Furthermore, it was observed in the present study that salinity fluctuation could influence spawning of green mussel, wherein the number of spent individuals increased after the sudden drop in water salinity from 30 to 13 ppt after the heavy rainfall, an indication that spawning had occurred. The presence of individuals with spawning stages was also observed throughout of period of sampling which indicates that mussels were continuously breeding in the area. The highest percentage of individuals having spawning stages were recorded in October and November. The information on the factors that affect gonadal maturation and spawning schedule can help mussel growers predict the schedule of spatfall

ELBA BIOFLUX

Abstract. An eight-week feeding trial was conducted to evaluate the effects of combined supplementation of peptidoglycan and mannan oligosaccharide (MOS) in tiger shrimp, Penaeus monodon. Tiger shrimp (0.29 ± 0.02 g) were fed diets supplemented with different levels of peptidoglycan + (MOS) as immunostimulants for six (6) and eight (8) weeks. Four (4) experimental diets were formulated to contain 0, 0.1, 0.2, and 0.4% peptidoglycan + MOS. The feeding trial was conducted in 250 L capacity concrete circular tanks (replicated four (4) times) with 20 shrimp per tank. Growth, survival, respiratory burst activity, total hemocyte count (THC), and in vivo resistance to WSV infection were evaluated. Weight gain of the shrimp was significantly higher in the immunostimulant-fed groups compared to the control. However, different levels of the immunostimulants did not differ in their effect on the the growth of the shrimp. On the other hand, respiratory burst activity and total haemocyte count (THC) were significantly higher in the group supplemented with 0.2% peptidoglycan + MOS than the rest of the treatments. Likewise, survival after infection with White Spot Virus (WSV) was significantly increased in the 0.2% peptidoglycan + MOS compared to the other groups. The present results demonstrated that using peptidoglycan and MOS together at 0.2% of the diet improves growth, activates immune responses such as respiratory burst activity and THC in P. monodon and give better protection to the shrimp against WSV infection

Verification of a hatchery protocol for green mussel Perna viridis spat production in the Philippines using industry-scale facilities

Hatchery seed production of mussels has been identified as a sustainable method to address the problem of low production due to insufficient seed supply. We conducted the first hatchery production trials of the Asian green mussel Perna viridis spats in the Philippines to demonstrate the feasibility of producing a sufficient and reliable seed supply for grow-out operations. However, results of small-scale experiments cannot be directly rolled-out commercially unless these are verified in bigger-scale facilities approximating those of commercial hatcheries. Thus, techniques on broodstock collection, spawning, and larval rearing, developed by the project in the laboratory during the experimental trials, were applied and verified in a production run using industry-scale tank facilities. Mature broodstocks collected from traditional mussel growing areas were successfully spawned in the hatchery. Eggs were fertilized, and these developed into D-hinged larvae, pediveliger, and metamorphosed into early spat before fully developing into the spat stage. Successful larval rearing up to the spat stage required the use of appropriate algal species and rates of feeding, close monitoring of larval stages, and water quality management. The survival from eggs to D-hinged larvae, D-hinged larvae to pediveliger, pediveliger to early spat, D-hinged larvae to early spat, and early spat (1 mm) to fully grown spat was 77, 64, 6.4, 3.1, and 72%, respectively. This study has established the feasibility of producing P. viridis in commercial-scale hatchery facilities

Fermented Copra Meal as Replacement for Dietary Fish Meal Protein in Grow-Out Culture of Black Tiger Shrimp, Penaeus monodon Juveniles

Feeding trials were conducted to assess the effects of diets containing fermented copra (FCM) as an alternative to fish meal (FM) on growth, survival, and feed efficiency, in Black Tiger Shrimp, Penaeus monodon. A diet was formulated where 40% of the FM protein was replaced by FCM protein, and compared with a commercial shrimp diet. The feeding experiments were carried out using 10-ton capacity circular outdoor tanks. Three hundred and fifty (350) shrimp were stocked in each tank at a density of 35 shrimp per m3. They were fed the diets at a rate which decreased from 15% down to 4% of average body weight (ABW) per day. The results demonstrated that growth, survival, and feed performance, in P. monodon in outdoor tanks were not affected by replacing 40% of the dietary FM with FCM protein. Furthermore, no difference was found in proximate composition of the shrimp carcass fed the commercial and experimental diets. Although protein efficiency ratio (PER) of the commercial and FCM-based diets were similar, protein productive value (PPV) was significantly higher in the FCM than the commercial diet. Hence, we concluded that FCM is a promising alternative protein source for Black Tiger shrimp and can replace 40% of the fish meal protein without adversely affecting growth, survival, and feed efficiency

Use of immunostimulants in shrimp culture: An update

Different approaches are used to prevent and control diseases in aquaculture. Immunostimulation is one method that is gaining popularity and is considered a promising development in aquaculture. Immunostimulants were found to be effective in enhancing parameters of non-specific immunity and resistance to diseases of fish and crustaceans. However, some issues raised on the use of immunostimulants pertains to the short-term nature of immune indices used during efficacy evaluation, possible detrimental effects during long-term administration, or self-damage due to unregulated production of immune effectors. Further testing in large-scale production units has been recommended. This chapter presents the various types and sources of immunostimulants commonly used in aquaculture and in shrimp culture in particular. The effects of each immunostimulant vary depending on its source, dose, route of administration, length of exposure, and the species to which it is administered

Effects of Partial Replacement of Fish Meal by Fermented Copra Meal on the Growth and Feed Efficiency in Black Tiger Shrimp, Penaeus monodon

The potential of fermented copra meal (FCM) as an alternative to fish meal as a protein source for tiger shrimp, Penaeus monodon practical diet was evaluated. Five isonitrogenous (41% crude protein) diets with 0, 10, 20, 30 and 40% fish meal protein replaced with protein from FCM were formulated. P. monodon (average weight 0.38 ± 0.02 g) were distributed in 100 L capacity fiberglass tanks at 20 shrimp each. The diets were fed 4 times daily for 9 weeks initially at 15% of the shrimp ABW and reduced to 8%. The experiment was conducted in triplicate in a flow-through culture system. The parameters examined include growth, feed conversion ratio (FCR), survival, whole body nutrient composition, protein efficiency ratio (PER), and protein productive value (PPV) as a measure of protein retention. After the feeding trial, results demonstrated that regardless of the FCM replacement level in the diet, no significant differences were observed in all the parameters (growth, FCR, survival, whole body nutrient composition, PER and PPV) measured. Thus, fermented copra meal can be used as alternative protein source and can replace up to 40% of the fish meal protein in black tiger shrimp practical diet

Growth, plasma cortisol, liver and kidney histology, and resistance to vibriosis in brown-marbled grouper, Epinephelus fuscoguttatus fed onion and ginger

The health-promoting effects of dietary onion and ginger were studied in brown marbled grouper, Epinephelus fuscoguttatus. An eight-week feeding trial was conducted to evaluate the effects of dietary onion and ginger on growth, cortisol levels, histology and disease resistance in the fish. Five experimental diets were formulated to contain either onion (2%), ginger (2%), β-glucan (1%) or vitamin C (3%) and a control diet (without immunostimulants). Each diet was fed to triplicate groups of fish with an average weight of 10.85±0.69 g. Fish supplemented with either of the immunostimulants exhibited a significantly higher growth compared to the control group. Specific growth rate (SGR) and feed conversion efficiency (FCE) were significantly higher in the onion and ginger-supplemented fish than the control. Cortisol level was higher in the control compared to the immunostimulant-fed groups with onion and ginger-fed fish showing significantly lower cortisol levels. When experimentally infected with Vibrio harveyi, fish fed onion or ginger exhibited significantly reduced mortality when compared with the control and β-glucan, but not when compared with the vitamin C-fed group. Liver sections sampled 4 days postinfection showed no remarkable pathology except for the slight reduction in glycogen granules in the supplement-fed fish. The liver of non-supplemented infected fish showed necrosis, fatty globule deposition, vacuolation, and presence of short rod-shaped bacteria. Kidney sections in the supplemented groups, likewise, did not show significant pathology similar to the uninfected control, whereas those of infected control fish showed necrosis of the tubules and glomeruli resulting in severely altered morphology of the tissues and presence of bacteria in the necrotic areas. As a result of circumventing tissue damage, wound healing was faster in fish supplemented with ginger, onion, and vitamin C compared to the β-glucan and the control groups. This study showed the benefits of onion and ginger in promoting growth and alleviating stress and severity of vibriosis in grouper.The University of the Philippines Visayas is gratefully acknowledged for providing the research fund and the Southeast Asian Fisheries Development Center, Aquaculture Department (SEAFDEC/AQD) for the use of their research facilities

Screening of vibriosis in Asian seabass, Lates calcarifer using loop-mediated isothermal amplification (LAMP) assay

The aim of this study was to standardize a loop-mediated isothermal amplification (LAMP) assay for the detection of Vibrio harveyi , the causative agent of vibriosis in Asian seabass, Lates calcarifer. The dnaJ gene of the bacterial pathogen was used as the target gene for the LAMP assay. It was optimized at an incubation time of 1 h at 63°C. The assay was highly specific for V. harveyi and did not cross-react with other bacterial pathogens offish. However, the assay was able to detect V. harveyi that was isolated from infected shrimps. The limit of detection of the LAMP assay was 40 pg of DNA mL-1 or 40 fg of the genomic DNA per LAMP reaction and was 10 times more sensitive than conventional PCR in detecting the bacterial pathogen from infected samples. The LAMP products can be quantified spectrophotometrically using hydroxynaphthol blue (HNB) dye and showed positive correlation with the amount of the pathogen. These results demonstrated that LAMP is a simple and sensitive detection technique that has potential application for routine diagnosis of vibrosis caused by V. harveyi in Asian seabass and other aquatic species.The use of the facilities at the National Institute of Molecular Biology and Biotechnology (NIMBB), University of the Philippines Visayas and at the Fish Health Laboratory of the Southeast Asian Fisheries Development Center (SEAFDEC) is gratefully acknowledged