The profitability of the fishpen industry in Laguna de Bay cannot be over-emphasized. However, a good engineering design must be prepared, in addition to the feasibility study in production and marketing. The destructive effect of the past typhoons which hit the Philippines especially in 1974 has shown the susceptibility of these fishpens to failures. To protect the industry from collapsing due to these calamities, better enclosure designs have to be developed. It is therefore hoped that the two design models presented will stimulate a more rigorous investigation of the present system. The SEAFDEC Freshwater Aquaculture Station will be putting up some experiments on the design models herein discussed. It is also recommended that studies be made on the wave characteristics of the lake water and water hyacinth movements all year round. The extensive use of floating cages for fish culture in other countries has proved to be successful. In the Philippines, this kind of fish culture was introduced in the culture of Tilapia in the lakes of San Pablo City, Laguna, notably in the Bunot Lake. Because of this, the Freshwater Station has included in its projects a study of the design and construction of floating cages with emphasis on the kinds of materials for floatation and support system.

With the advent of new research and studies into aquaculture practices there is a need to improve the size and shape of brackishwater ponds in the Philippines and to make their management more efficient. This article discusses the survey and layout of the project and the engineering aspects of pond management. Milkfish pond management is also considered.

We monitored the abundance of a non-native (Rhinogobius sp. OR) and two native stream gobies (R. fluviatilis and R. nagoyae) over a decade, from 1995 to 2004, in a fixed reach of a tributary of the Kamo River, southwestern Japan. The non-native Rhinogobius sp. OR appeared and reproduced in 1997, when an increased deposition of fine sediments occurred. However, after a severe spate in 1999, the non-native goby almost completely disappeared from the study reach, while the density of the native R. fluviatilis increased. The severe spate is likely to have prevented the establishment of the non-native goby. Our results provide an example of abiotic barriers to invasion.

Different microalgae as larval food for Holothuria scabra, a high-value sea cucumber species with hatchery technology continually being refined to improve production, were studied. Two experiments were conducted to determine the performance of the larvae—first, the use of single-algal diet of either Chaetoceros calcitrans, Rhodomonas sp., or Tetraselmis tetrathele as feed; and second, the use of a combination of two algal species, C. calcitrans + Rhodomonas sp., C. calcitrans + T. tetrathele, or Rhodomonas sp. + T. tetrathele as feed. For both experiments, hatched larvae at 2 days post-fertilization (DPF) were used for initial stocking at a density of 200 larvae L⁻¹. Growth, development, and survival were monitored until more than 50% of the larval population were considered as competent larvae (late auricularia). In the first experiment, during the early stage of development (early aricularia), larvae fed Rhodomonas sp. were larger compared to other treatments. However, when the larvae reached middle and late auricularia, they performed better when fed with C. calcitrans. Those larvae fed with C. calcitrans were significantly larger and showed faster development to competent larvae. In the second experiment, larvae fed mixed C. calcitrans + Rhodomonas sp. showed better performance in growth, development, and survival. The present study showed that C. calcitrans, when used solely as feed or in combination with Rhodomonas sp., promoted better growth, development, and survival of H. scabra larvae.

The COVID-19 outbreak situation brought into focus not only the safety but also the mental wellbeing of nursing students. At present, the level of fear of COVID-19 and associated factors among nursing students in the Philippines is not well understood. This cross-sectional online survey determined the relationship between Internet use and eHealth literacy with fear of COVID-19. One thousand three hundred and sixty-seven (n=1,367) answered an online survey using the adopted eHealth Literacy Scale (eHEALS), and Fear of COVID-19 Scale (FCV-19S) administered from May 1 to 15, 2020. Descriptive statistics, tests for differences, and correlational analysis were performed. Results indicated that the composite score of the FCV-19S was 3.65, indicating moderate to high levels of fear. Fear of COVID-19 significantly differed based on sex, year level, and location. A significant inverse relationship was found between the average daily use of the Internet and fear of COVID-19. On the other hand, no significant association was noted between eHealth literacy and fear of COVID-19. The first wave of the COVID-19 outbreak has resulted in a far-reaching impact on nursing students' psychological wellbeing. This study highlights the value of the Internet and its use during the outbreak may not always lead to higher fear related to COVID-19. Nursing schools may need to create strategies to promote regulated and responsible Internet use, address students' mental health concerns and develop interventions to respond proactively to mitigate or reduce fear among nursing students during the pandemic.

Hatchery production of the tropical sea cucumber Holothuria scabra or sandfish has been successfully demonstrated in various countries, especially during the past decade. However, the main bottleneck in up-scaling production of larger sandfish juveniles is in the nursery phase where land-based facilities are limited in the Philippines compared to other countries. This has led to some promising pioneering research in ocean-based sandfish nurseries in the Philippines. However, site-specific and seasonal inconsistencies in production levels were observed. In this study, a comprehensive experiment comparing 17 replicated nursery culture operations of sandfish juveniles using floating hapas, was conducted across four sites with distinct geo-climatic zones in the Philippines and at different months from 2013 to 2016. We evaluated the performance of the ocean-based floating hapa nursery system by determining the effects of periphyton characteristics and broad-scale differences in meteorological variables to growth and survival of juvenile sandfish within different geo-climatic zones. Our data confirmed high spatial (across site) and temporal (among trials within site) variability in sandfish culture performances. Wind stress was the most significant driver of this variation, which negatively influenced growth and survival of juveniles especially during Cycle 1 (first 30 d). Sandfish growth was positively related to Chl-a and mean temperature, but was negatively impacted by Wind stress, Autotropic Index (AI), total rainfall (∑Rain), and sea-surface atmospheric pressure; while survival was positively affected by phaeophytin and Ash-Free Dry Weight (AFDW) content of the hapa biofilm. In Cycle 2 (succeeding 31–60 d), growth and survival was greatly influenced negatively by the re-stocked density (number of individuals surviving from Cycle 1), while survival was further affected negatively by ∑Rain and AFDW. Our results provide significant information on suitable ocean nursery conditions, periphyton/biofilm characteristics, and spatial-temporal considerations for optimizing production of H. scabra juveniles in floating hapas. We also highlight the negative effects of increasing biomass density when on-growing larger juveniles in this system. These insights are valuable in optimizing management and operation of ocean nurseries for sandfish, not only in various potential sites in the Philippines, but also in many developing tropical countries in the Indo-Pacific.

Seaweed cultivation is the fastest‐growing aquaculture sector, with a demonstrable potential to drive development in some of the poorest coastal populations worldwide. However, sustainable exploitation, fair access and equitable benefits from marine genetic resources, such as seaweeds have yet to be fully realised. Patchy fundamental knowledge on the genetic diversity and metabolic potential of algae limits their exploitation; scant practical skills and low investment in breeding restricts germplasm availability and the Nagoya protocol has only partially remediated insufficient governance. Further developments and the addressing of knowledge gaps in relation to biosecurity, breeders’ rights and conservation of genetic resources are needed for progress.

An innovative microalgae harvesting technique was carried out under various anode/cathode (2/2, 4/4 and 6/6) configuration and at different voltage treatment (3, 6 and 10 V) to efficiently electroflocculate Chaetoceros calcitrans. This study was conducted to determine the optimal configuration of electrode units (Pb and Al) and voltage settings that could improve the quality of harvested paste in terms of nutritional value and metal contamination for its later use in aquaculture. The use of 6/6 electrodes achieved the shortest harvest time of 48 ± 1 min and the lowest Pb content (83.7 ± 0.3 ppm). In terms of voltage treatment, harvest time was inversely proportional to the voltage used. However, Pb content was significantly lowest in the paste produced using 3 V (41.78 ± 0.12 ppm), when compared to those harvested under 6 V (304.35 ± 0.79 ppm) and 10 V (343.90 ± 0.91 ppm) treatment. Likewise, Pb residues in the resulting effluent are also lowest (0.245 ± 0 ppm) with 3 V treatments. C. calcitrans paste can be resuspended ≤6 months but with a lag phase of 3–4 days for use as starter culture. A 97% reduction in Pb content of C. calcitrans paste and 77% reduction in Pb content were obtained in Artemia (7.8%) fed C. calcitrans paste.

This paper elucidates the developmental profiles of iodide and thyroid hormones, thyroxine (T₄) and triiodothyronine (T₃) in hatchery-reared rabbitfish (Siganus guttatus) during early larval development. The study evaluated the levels of iodide, T₄ and T₃ tissue content in rabbitfish larvae at 0, 10, 20, 30, 40 and 50 days after hatching (DAH). Under normal rearing conditions, iodide (11.98 ± 4.3 nmol g⁻¹) and thyroid hormones (T₄: 0.09 ± 0.01 nmol g⁻¹; T₃: 0.01 ± 8.5E-05 nmol g⁻¹ were already detected from newly-hatched larvae and their presence has been attributed from maternal origin. Iodide level sharply peaked at 10 DAH (1416.43 ± 149.6 nmol g⁻¹) which is significantly higher compared to the iodide levels in the larvae at 20, 30, 40 and 50 DAH. The levels of THs gradually increased as the larvae developed with T₄ (0.96 ± 0.05 nmol g⁻¹) and T₃ (0.03 ± 0.004 nmol g⁻¹) exhibiting a peak on 20 and 30 DAH, respectively, which coincided with the onset of metamorphosis. Thyroid hormone levels gradually decreased which coincided also with the completion of metamorphosis. The present findings indicated a pattern of the rise and fall in iodide and thyroid hormone levels during larval development and its role in metamorphosis of rabbitfish larvae. The study has reported for the first time, the changes in iodide and thyroid hormone levels during the early developmental stage in hatchery-reared rabbitfish and the results are in agreement with those vital actions of thyroid hormones in other fish species.