The ability of bacteria to metabolize a wide variety of carbon sources has been known to aid in their ability for efficient colonization. Vibrio parahaemolyticus, a known aquatic pathogen has been reported to have the ability to metabolize a number of carbohydrates including D-glucose, D-galactose, L-arabinose, D-mannose, and D-ribose to name a few. Classical isolation of V. parahaemolyticus from other members of the family Vibrionaceae relies on its carbon utilization pattern. Conventionally, V. parahaemolyticus lacks the ability to utilize sucrose and this has been the basis for its isolation using the Thiosulfate-citrate-bile salts-sucrose (TCBS) agar. Reports of V. parahaemolyticus having the ability to utilize sucrose have been presented yet there is paucity of information and detailed study on this phenotype. In this study, we report the V. parahaemolyticus strain PH05 that has the ability to metabolize sucrose. Phenotypic and genotypic characterization of this V. parahaemolyticus strain isolated from Negros Island, Philippines, revealed that V. parahaemolyticus strain PH05 is atypical appearing yellow on TCBS agar plates. It is capable of utilizing sucrose, unlike the majority of V. parahaemolyticus isolates. Genome analyses of this strain revealed the presence of a chromosomally encoded sucrose operon-like gene cluster encoded in chromosome 2 with the following sucrose-utilization associated genes: scrY, ccpA, treP, scrK, and scrB genes coding for sucrose porin, catabolite control protein A, PTS System sucrose-specific EIIBC component, fructokinase, and sucrose-6-phosphate hydrolase. The mode of transmission of these genes to V. parahaemolyticus strain PH05 is still unknown. However, the presence of insertion sequences (IS) and phage elements in the same chromosome suggests horizontal gene transfer events. Taken together, our results point to the possibility that acquired sucrose utilization genes may contribute to the fitness of V. parahaemolyticus strain PH05 in the environment.

This project established a sustainable aquaculture industry for giant grouper in Vietnam and the Philippines through the development of captive breeding and larval-rearing techniques. Captive breeding innovations and larval-rearing techniques, developed through a collaborative Fisheries project, are sustaining the aquaculture industry for giant grouper in Vietnam and the Philippines. Groupers are vital to the live reef food-fish trade in South-East Asia, and the giant grouper is a high-value, fast-growing species with significant aquaculture potential. Establishing a sustainable giant grouper aquaculture industry is a high priority for the region, but research is hampered by the high level of investment required to hold and maintain giant grouper broodstock. Lack of commercial production is also due to limited knowledge about the giant grouper’s maturation and spawning behaviour, and low larval survival.

This study evaluated the suitability of five diatom species (Amphora sp., Cocconeis sp., Navicula ramosissima, Nitzschia sp., and Tryblionella sp.) as food to abalone Haliotis asinina early juveniles (5-mm shell length). Grazing periodicity, grazing rate, and feeding preference were measured; at the same time, abalone gut content was examined. Grazing incidence appeared to be continuous with significantly higher grazing intensity observed at nighttime from 6 p.m. to 10 p.m. (79%) than at daytime from 10 a.m. to 2 p.m. (40%) (p < 0.05). Grazing rates from 6 p.m. to 10 p.m. were significantly higher on N. ramosissima (1.6 × 105) among diatom species but was not statistically different from Cocconeis sp. (1.1 × 105) (p > 0.05). Broken cells of Amphora sp. (22%) were significantly higher in the gut of H. asinina compared to Cocconeis sp. (2.8%), N. ramosissima, (1.8%), and Tryblionella sp. (0.2%) although the abundance of Nitzschia sp. (6%) was not significantly different from Amphora sp. (p > 0.05). Early juveniles showed significant preference for Cocconeis sp. (18.6%), followed by Nitzschia sp. (16.2%), N. ramosissima (13.9%), and Amphora sp. (13.4%), with the least preference for Tryblionella sp. (7.8%). Survival of H. asinina was similar in 4 diatom species (46–71%) except in Tryblionella sp. (8–12%). These findings suggest that diatom species Cocconeis sp., Nitzschia sp., Amphora sp., and N. ramosissima are the suitable live food for H. asinina early juveniles. Knowledge from this study would contribute to the development of a feeding protocol that would maximize production of H. asinina early juveniles in the hatchery.

This study determined the seasonality of Magallana bilineata spat settlement in a natural oyster bed and established surface texture preference of competent larvae by comparing the numbers of spat settling on the smooth and rough surfaces of ceramic tiles over a period of 31 months. This will guide farmers when to deploy cultches to maximise spat harvest. Regardless of tile orientation, spat numbers were significantly higher on the rough side (129.07 ± 9.3 m⁻²) than on the smooth side (66.95 ± 7.0 m⁻²). Spat collection was highest in March, June and July in each of 2015, 2016 and 2017. There was no significant correlation between the number of spat settling in each month with temperature, salinity, pH, dissolved oxygen (DO), sulphide, phosphate, nitrate, nitrite and ammonia concentrations, plankton density measured at deployment and retrieval of tiles, except for DO during deployment. The only significant correlations with mean shell length (SL) were with DO and ammonia during tile retrieval. Mean SL did not significantly differ between tile orientations and surfaces but differed between months, being highest in August 2015 and August 2016. From these results, it is best to deploy roughened cultches in this particular area in March, June and July.

Effect of tank color in combination with substrate-shelters on the survival and growth of the instar of purple mud crab, Scylla tranquebarica (initial body weight of 28.7 ± 2 mg) was investigated. Ten treatments were tested in triplicate with black (B) and white (W) tanks were set as the control, while other tanks were provided with a combination of sand substrate (S), and/or polyvinyl chloride pipes (P) as horizontal and nets (N) as vertical shelter, referred as B, BS, BSP, BSN, BSPN, W, WS, WSP, WSN and WSPN, respectively. Survival of the instar in black tanks (26.7 to 60.0%) was higher than in white tanks (20.0 to 46.7%) (P = 0.052). Survival in the horizontal shelter treatments (46.7 and 63.3%) exceeded that in the vertical shelter groups (30.0 and 50.0%) (P = 0.068). The final body weight of the instar in black tank (2.4 to 3.8 g) was significantly lower than white tank (2.6 to 4.8 g) (P = 0.02). Specific growth rate was significantly greater in sand substrate treatments (8.4 to 9.1%/day) than in controls (7.9 and 8.0%/day) (P = 0.015). In conclusion, horizontal shelter was better than vertical type, and black tank with substrate and horizontal shelter was more suitable for culture of purple mud crab instar.

The shrimp aquaculture industry is a major economic player in the food and livelihood sectors, both globally and in the Philippines. The development of industrialized shrimp farming methods has led to a rapid increase in cultured shrimp production since the 1980s, but the industry has also faced challenges from the introduction of opportunistic pathogens. These pose severe limitations in the success of shrimp culture in both hatcheries and grow-out ponds. We extracted genomic DNA from 423 bacterial isolates from shrimp disease outbreaks in local aquaculture farms throughout the Philippines and subjected them to Illumina paired-end whole-genome sequencing at 50–100-fold coverage. Reads were assembled using a de novo approach, and average nucleotide identity measurements were used to establish the identity of the isolates. Outbreak types encountered during the time of sampling include acute hepatopancreatic necrosis disease (AHPND), luminescent vibriosis, white spot disease, and outbreaks of unknown etiology. In both outbreak and non-outbreak sites, members of the genus Vibrio, particularly Vibrio parahaemolyticus, were observed to be the most abundant. The whole-genome sequence data obtained will aid in the design and implementation of novel shrimp bacterial disease outbreak management and control programs.

The cost efficiency of stake and rack-hanging methods of farming oysters are compared. Annual costs and returns data for both methods were obtained from a socioeconomic survey conducted in 1991 at the Aquaculture Department of the Southeast Asian Fisheries Development Center (SEAFDEC/AQD). On average, 14 kg m⁻² (shell-on) and 22 kg m⁻² (shell-on) were produced using the stake and rack-hanging methods, respectively. The translog cost function for 58 oyster farms was estimated using iterative seemingly unrelated regression (SUR). Statistical analysis indicates that the higher production from the rack-hanging method is significantly different (α=0.10) from the production using the stake method. The cost-efficient method varied based on production levels. At output levels less that 9044 kg (shell-on), the rack-hanging method had lower average cost per unit, and for higher production levels the stake method had the lower average costs. Similar conclusions were drawn from the marginal cost analysis. Results imply when production is less than 9044 kg, then the most efficient technology is the rack-hanging method and if production is greater than 9044 kg, the most efficient method is the stake method.