The bacterial isolate HJ1, which was identified as a Methylobacterium sp., grew on 2, 2-dichloropropionic acid as the sole carbon source and produced a 2-haloalkanoic acid hydrolytic dehalogenase. This non-stereospecific dehalogenase E (DehE) catalysed the hydrolytic dechlorination of 2, 2-dichloropropionic acid and D, L-2-chloropropionic acid to produce pyruvate and lactate, respectively. The enzyme was purified to homogeneity and characterized. The molecular weight was 36 kDa by SDS-polyacrylamide gel electrophoresis and 72 kDa by gel filtration, suggesting that the enzyme is a protein dimer. The purified enzyme was only inhibited by HgSO₄ and was non-stereospecific to haloalkanoic acids. The K_m value for the hydrolysis of 2, 2-dichloropropionic acid was 0.25 mM. The enzyme removes chloride present on the α-position, but not on the β-position, of a number 2-carbon alkanoic acids.

Kappaphycus striatum var. sacol was grown in two separate studies: (1) at two stocking densities, and (2) at four different depths, each for three different durations of culture (30, 45 and 60 days) in order to determine the growth rate of the seaweed and evaluate the carrageenan content and its molecular weight. The results demonstrated that stocking density, duration of culture and depth significantly (P < 0.01) affected the growth rate, carrageenan content and molecular weight of K. striatum var. sacol. Decreasing growth rate was observed at both stocking densities and at four depths as duration of culture increased. A lower stocking density (500 g m^–1line^–1) showed a higher growth rate for the shortest durations, i.e. 30 days, as compared to those grown at a higher density. Likewise, decreasing growth rate was observed as depth increased, except at 50 cm after 60 days of culture. A 45-day culture period produced the highest molecular weight at both stocking densities (500 g m^–1line^–1 = 1,079.5 ± 31.8 kDa, 1,000 g m^–1line^–1 = 1,167±270.6 kDa). 'Sacol' grown for 30 days at 50 cm (1,178 kDa) to 100 cm (1,200 kDa) depth showed the highest values of molecular weight of carrageenan extracted. The results suggested that K. striatum var. sacol is best grown at a stocking density of 500 g m^–1line^–1, at a depth of 50-100 cm, and for a duration of 30 days in order to provide the highest growth rate, carrageenan content and molecular weight.

Lacking a propensity to emerge over the mud surface, the eel goby, Odontamblyopus lacepedii, survives low tide periods by continuously breathing air in burrows filled with hypoxic water. As with most marine air-breathing fishes, O. lacepedii does not possess an accessory air-breathing organ, but holds air in the buccal-opercular cavity. The present study aimed to clarify how the respiratory vasculature has been modified in this facultative air-breathing fish. Results showed that the gills apparently lacked structural modifications for air breathing, whereas the inner epithelia of the opercula were richly vascularized. Comparison with two sympatric gobies revealed that the density of blood capillaries within 10?m from the inner opercular epithelial surface in O. lacepedii (14.5 ± 3.0 capillaries mm^-1; mean ± s.d., n = 3) was significantly higher than in the aquatic non-air-breathing Acanthogobius hasta (0.0 ± 0.0) but significantly lower than in the amphibious air-breathing mudskipper, Periophthalmus modestus (59.1 ± 8.5). The opercular capillary bed was supplied predominantly by the 1st efferent branchial arteries (EBA1) and drained by the opercular veins, which open into the anterior cardinal vein. Deep invaginations at the distal end of the EBA1 and the junction with EBA2 are suggestive of blood flow regulatory sites during breath-holding and apnoeic periods. It remains to be investigated how blood flow through the gills is maintained during breath holding when the buccal–opercular cavity is filled with air.

Prevalence of monodon baculovirus (MBV) was determined using polymerase chain reaction (PCR) on deoxyribonucleic acid (DNA) extracts from the hepatopancreas of the wild black tiger shrimp, Penaeus monodon collected from 7 sampling sites in the Philippines. These sites are considered as the primary sources of broodstock and spawners used for hatchery operations. MBV was detected from all sites except Palawan during the dry season and Negros Occidental and Bohol during wet season. The prevalence of MBV showed no seasonal, sex and size variations. These results show that MBV is an established viral infection in wild populations of Penaeus monodon in the Philippines. Broodstock collected from the contaminated sites could serve as a reservoir of the virus which could infect the post-larvae used to stock in grow-out ponds.

Mangrove forests have been cleared at an alarming rate over the last century to allow space for settlements, agriculture and aquaculture and are still used today for fuel and construction. However, in the last few decades the value of the range of services and products that mangroves supply are being increasingly appreciated by policy makers. Mangrove replanting is frequently used as a method of restoring ecological function and associated goods and services but this may not be justified as once diverse forests are often replanted with mono-genus stands. In the present study the abundance of the commercially important mud crab Scylla olivacea, a top benthic predator, was used as an indicator of the ecological function of mangrove habitats. Abundance was estimated using catch per unit effort (CPUE) data obtained from an experimental standardized trapping grid. The same commercial traps also catch two other smaller non-exploited competing species, Baptozius vinosus and Thalamita crenata that are discarded by fishers. The relative abundance of these three species was used to separate the effects of habitat from fishing pressure and recruitment limitation. Four sites on Panay Island, central Philippines were selected to represent different types of mangrove habitat; a replanted fringing area predominantly of Rhizophora spp., a natural fringing area predominantly of Sonneratia spp., a diverse natural basin mangrove area and a degraded mangrove site. The relative abundance of mud crabs was found to be equivalent in the natural fringing mangrove (1.89 crabs trap⁻¹ day⁻¹) and the replanted mangrove area (1.71 and 0.81 crabs trap⁻¹ day⁻¹). Lower densities of S. olivacea in the basin mangrove area (0.33 crabs trap⁻¹ day⁻¹) appear to be due to limited recruitment, and at this site there was instead a higher abundance of the other non-commercial crab species. No mud crabs were caught in the degraded mangrove area and CPUE for other crab species was also low. Overall, the study suggests that replanting of mangroves even in mono-genus stands was effective in restoring mud crab populations, indicating recovery of an ecological function to a level equivalent to that of natural mangrove environments. The use of CPUE as an indictor of relative abundance of S. olivacea was supported by single release mark–recapture studies and a multiple release mark–recapture study in the replanted mangrove site.

Early larval stages of mud crab Scylla serrata were exposed to different concentrations of nitrite (40, 80 and 160 mg L⁻¹ and a control, without added nitrite) and three salinity levels (25, 30 and 35 g L⁻¹) using a static renewal method. No interactive effect of nitrite and salinity was detected. Estimated LT₅₀ in 96-h toxicity tests decreased in all stages with increasing nitrite concentrations in all salinity levels. The 96-h LC₅₀ values of nitrite-N were 41.58, 63.04, 25.54, 29.98 and 69.93 mg L⁻¹ for zoea 1, 2, 3, 4 and 5 respectively. As the larvae grew, they showed a progressive increase in tolerance to nitrite. The toxicity of nitrite to larvae increased with exposure time. The median lethal concentration was not affected by salinity. The chloride component of salinity within 25–35 g L⁻¹ did not seem to be as effective in alleviating toxicity as has been reported in other crustacean species. Based on 96-h LC₅₀ and an application factor of 0.1, the ‘safe level’ of rearing mud crab larvae was calculated to be 4.16, 6.30, 2.55, 2.99 and 6.99 mg L⁻¹ nitrite-N for zoea 1, 2, 3, 4 and 5 respectively.

Ovarian maturation in adult wild-sourced and pond-grown Scylla serrata (Forsskål) was determined based on gross morphology and histological appearance. There were no significant differences noted in the histological features of both wild and pond-reared S. serrata females. Ovarian maturation was classified into five stages: immature, early maturing, late maturing, fully mature and spent. The immature ovaries are thin and translucent to off white and contain oogonia, primary oocytes with large nuclei. The follicle cells were found around the periphery of the lobes and an area among groups of oogonia and oocytes. The follicle cells gradually enclosed the oocytes. The early-maturing ovaries were yellow and small yolk globules started to appear in larger oocytes. In late-maturing ovaries, the colour became light orange and lobules were apparent. Yolk globules occurred in the cytoplasm with larger globular inclusions towards the periphery, while follicle cells were hardly recognizable. Fully mature ovaries were orange to deep orange and had swollen lobules. Large yolk globules were apparent in the entire cytoplasm. Follicle cells were hardly seen. Spent ovaries were similar to the early-maturing and late-maturing stage in partially spawned females. The ovarian development was correlated closely to the gonadosomatic index, oocyte diameter, and ovarian histology. The classification of ovarian maturation provides baseline information for further studies on reproductive biology. Likewise, the information provides a guide for broodstock management in the hatchery.

The capacity of a natural mangrove system in Ibajay, Aklan province, central Philippines to process shrimp pond culture effluents was assessed through analysis of mangrove community structure and 24-hr monitoring of water quality parameters (NH₃-N, NO₃-N, PO₄-P, sulfide, and total suspended solids). Results from the latter showed decreased nutrient levels within 6 hrs after daytime draining of effluents into the mangrove stand, but only nitrate reduction was statistically significant. Based on nitrate loss, volume of water drained, mangrove area, and shrimp farming data (e.g., N loss from ponds, feed composition, feeding rate), calculations show that 1.8–5.4 ha of mangroves are required to remove nitrate wastes from 1 ha of shrimp pond. N uptake by the mangrove macroflora was supported by data showing longer nipa palm leaflets and faster mangrove seedling growth in the experimental mangrove receiving effluents compared to a control mangrove, but not from mangrove biomass measurements. These results have significant implications for the Philippine brackishwater pond culture industry to conserve or rehabilitate mangroves as potential pond biofilters, to implement legally mandated 20- and 50-m greenbelts, and to reverse the national 0.5 ha mangrove: 1.0 ha pond ratio.

Susceptibility of orange-spotted grouper Epinephelus coioides, Asian sea bass Lates calcarifer, mangrove red snapper Lutjanus argentimaculatus, milkfish Chanos chanos, and rabbitfish Siganus guttatus to piscine nodavirus from orange-spotted grouper was studied by experimental infection. The fish were intraperitoneally injected with 0.05 mL of the filtrate homogenate of infected organs from diseased grouper at 10^6.8, 10^5.8 or 10^4.8 TCID₅₀/fish, while the control group received 0.05 mL of Hanks’ balanced salt solution. Clinical signs such as lethargy, anorexia and darkened pigmentation were observed in the orange-spotted grouper, Asian sea bass, mangrove red snapper, and milkfish injected with high and medium doses of the homogenate. Although no or little mortality occurred in the experimentallyinfected fish 10 days post-inoculation, viral nervous necrosis specific lesions such as severe necrosis and vacuolation in the brain and retina were produced in these four fish species. The virus was reisolated in SSN-1 cells inoculated with the filtrated tissue homogenate of survivors in all doses for all four fish species. However, in the experimentally infected rabbitfish no histological lesion was observed, and no virus was reisolated. These results indicate that grouper, sea bass, mangrove red snapper, and milkfish are susceptible to the piscine nodavirus isolated from diseased grouper.

SEAFDEC Aquaculture Department (AQD) pioneered fish disease work in the Philippines and developed diagnostic tools through research. Its Diagnostic Service Laboratory was established in the late 1970s to serve the budding aquaculture industry. Through the assistance of SEAFDEC AQD, this service has been replicated by both private and government agencies involved in shrimp aquaculture, thus, data on disease occurrence and prevalence are already available in databases in various forms. Laboratory analysis of hatchery-reared shrimp postlarvae has become an important tool for marketing using both physical and health attributes as gauges for acceptance or rejection of specific batches. Through the years, the diagnostic tools have evolved from mere wet mount microscopy to molecular diagnostic techniques by means of polymerase chain reaction (PCR) to detect viruses. Despite this development, however, disease information is still patchy and difficult to use as decision-support tools because it remains in highly technical and in difficult to visualize information spreadsheets and tables. GIS is a tool that translates complex data in tables and spreadsheets into maps that provide visual displays of information in both spatial and temporal forms. It shows disease trends that are not presently seen and understood by all stakeholders. This paper will highlight the evolution of shrimp health monitoring as a marketing tool in the Philippines and how the application of GIS has helped in understanding disease patterns in the shrimp industry.