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.

The coastal waters off Tokoro, Okhotsk Sea have been characterized by a substantial decrease in primary production from spring to summer season which will have repercussions on the maintenance of the Japanese scallop Patinopecten yessoensis (Jay, 1857) culture. This study examined the seasonal changes in scallop growth, condition and organ indices in relation to environmental conditions, and compared the sinking particulate organic carbon (POC) flux as an estimate of food availability to scallop food requirements. Monthly specimens were obtained in July 2005, and from May 2006 to December 2008 off Tokoro, Okhotsk Sea. Growth parameters derived from the modified von Bertalanffy growth function of 885 scallop individuals were the mean asymptotic shell height H_∞=126.51 mm, Brody growth coefficient K=0.081 year⁻¹, and t₀=6.19 year. Condition (CI) and gonadosomatic indices (GSI) increased in April and May, decreased from June to September, but increased again from October until May. The adductor muscle index (AMI) increased from June to October, but declined from November until May when CI and GSI began to increase. Primary production (PP) and chlorophyll a biomass decreased from spring (25.75–29.74 µg C L⁻¹ h⁻¹ and 1.74–5.37 µg L⁻¹) to autumn (0.90–10.83 µg C L⁻¹ h⁻¹ and 0.29–0.75 µg L⁻¹) concurrent with decreasing CI and GSI, but no deleterious effect on AMI was evident during these periods. The sinking POC flux (25–68 mg C m⁻² day⁻¹) was low during summer when gonad activity was also low, but started to increase in autumn when gonad activity started to peak. Although a deficit in food availability (lower sinking POC fluxes than scallop food consumption) was observed during summer, the potential advection of organic matter from offshore to nearshore region may have provided additional source of food to bottom-cultured scallops, contributing in part to the increase in shell growth and somatic tissues.

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.

Rice is a major staple crop in the Philippines, which produces a large amount of rice each year. On the other hand, rice production generates biomass waste in the form of rice husks. In consideration of the rice husks’ potential as a biomass energy source and support the development of the rice husk gas stove technology in the Philippines, Engineer Alexis T. Belonio had published a grey literature (GL) entitled “Rice Husk Gas Stove Handbook.” Hence, to fully understand the impact of the technology, a citation analysis was conducted. The works that cited the GL were retrieved from Google Scholar using Harzing’s Publish or Perish software. The complete title of the GL was used as keywords for the search string. Results revealed that the GL was cited by 155 literatures written by 398 authors from 31 countries. Seventy-five (48.4%) of the 155 literatures were cited 797 times. The results showed the wide utilization and the impact of locally-published GL, thereby confirming GL’s value in research and development.

Late maturation and large size at maturity are significant challenges when administering hormonal treatments in captive broodstock. Here, we report the potential of yeast, Pichia pastoris, as a vehicle to orally deliver a recombinant gonadotropin-releasing hormone (rGnRH1) aimed at stimulating gonadal development in juvenile orange-spotted grouper, Epinephelus coioides. Two recombinant GnRH1 constructs were designed utilizing pPIC3.5, the yeast expression vector lacking a signal sequence, hence retaining the recombinant within the yeast. The first construct (rGnRH1_1xGAP) comprised of GnRH1 decapeptide and the GnRH-associated peptide (GAP) separated by a cleavage site. The second construct (rGnRH1_10x) consisted of ten GnRH1 decapeptides, each separated by a cleavage site. Expression of the two recombinant peptides was confirmed by mass spectrometry. ELISA for the GnRH analogue (GnRHa) was validated to determine the level of rGnRH1 from the yeast extracts. Parallelism between the serially diluted GnRHa and serially diluted extracts from recombinant yeast confirmed validity of the assay. A luciferase reporter assay showed stimulation of tilapia GnRH type 3 receptor by the yeast extract, suggesting biological activity in vitro. In a short term experiment, lyophilised yeast loaded in gelatine capsules and fed once to juvenile orange-spotted grouper resulted in a significantly higher plasma GnRH compared with the control. In a 4-week experiment, lyophilized yeast containing either rGnRH1_1xGAP or rGnRH1_10x was incorporated in fish pellets and fed daily at a dose of 1 μg rGnRH1/kg fish body weight/day. The mean gonadosomatic index and oocyte diameter did not vary between the treated and control fish. The mean plasma levels of FSH, LH and GnRH in the rGnRH1-fed and control fish did not also vary significantly, however there were individuals in the rGnRH1-fed groups that had increased level of the hormones. Together with histological evidence showing oocyte development in a proportion of fish fed with the recombinant, results of the present study point to a biological activity in vivo of the rGnRH1 in yeast. With further refinement, this technology has the potential to provide a non-invasive method for broodstock management of large, late-maturing species of fish and of small, delicate endangered species that require breeding in captivity.

This is the first report on hydrodynamic models to determine current and water residence time patterns for Matarinao and Murcielagos bays in the Philippines, which have a long history of harmful algal blooms (HABs). Field surveys were conducted in Matarinao Bay in April and August 2010 and in Murcielagos Bay in February 2011. Hydrodynamic models of the bays were developed, and spatially explicit water residence times were estimated from the models based on rates of concentration decrease of a tracer within the bay. Both bays exhibited two distinct areas – the mouth with faster current flow and low residence time, and the head area with slower current flow and higher residence time. During the southwest monsoon, the residence time at Matarinao Bay was 5 d longer than that during the northeast monsoon. Phytoplankton sampling in both bays confirmed blooms of Pyrodinium bahamense, but the spatial distribution did not consistently correlate with the simulated residence time patterns. While residence time plays a significant role in algal blooms, extraneous factors may also influence the distribution of phytoplankton within embayments.