Author: ovcre.upvisayas

This study examines the environmental conditions and hydrographic dynamics in Tawi-Tawi within the Sulu Archipelago, a region influenced by the interplay of distinct water masses from the cooler, saltier Sulu Sea and the warmer, fresher Celebes Sea. Pronounced spatial gradients in sea surface temperature and salinity were observed; however, these hydrographic patterns did not correlate directly with Chl a concentrations or microbial plankton biomass, indicating that biological productivity is more strongly governed by current velocity and tidal dynamics. Spectral analysis confirmed tidal currents as the dominant driver of water transport, explaining over 95% of the variability in the region. Tidal currents can induce horizontal advection and retention zones on the shallow (<200 m) bathymetric shelves around Bongao, Sibutu, and Sitangkai, which promote plankton aggregation and enhanced nutrient mixing. Baroclinic tides were generated by the interaction of barotropic tides with complex bathymetry, such as in Sibutu and Sitangkai. This interaction produces internal waves that support vertical nutrient flux and persistent upwelling, enriching surface waters as evidenced by elevated Chl a and microbial density in Tawi-Tawi. Sampling during highest high water further intensified vertical mixing, nutrient availability, and horizontal advection, collectively elevating picoplankton and virioplankton abundance. The microbial community was dominated by viruses and heterotrophic bacteria, but Synechococcus prevailed among the autotrophs due to its high adaptability to dynamic mixing conditions. The spatial heterogeneity in microbial populations reflects the combined influence of physical transport processes and the ecological tolerances of plankton, underscoring the complexity of biological productivity regulation in this archipelagic system

Limpets are key herbivores in marine ecosystems, especially in high-energy rocky intertidal habitats where they regulate algal proliferation, create microhabitats, and foster unique biological communities. Despite their ecological significance, the limpet ecology in the Philippines remains understudied. This study assessed the distribution, abundance, and size structure of limpets on rocky shores at the southern tip of Panay Island, Philippines. Three study sites were surveyed using the standard transect-quadrat method to determine species composition and densities, with shell lengths (SL) measured to assess population size structure. A total of 331 limpets were recorded across all sites, representing three species: Siphonaria javanica, Siphonaria laciniosa, and Patelloida saccharina. The abundance of each species varied between sites. S. javanica exhibited the highest density, with an overall mean of 2.27 individuals 0.25 m-2, while P. saccharina had the lowest count with only four individuals observed. Limpets predominantly occupied the mid shore (1.00 m above Chart Datum, C.D.) and high shore (1.50 m above C.D.) levels, with each species demonstrating a preference for specific tidal heights. Shell lengths ranged from 1.00 to 29.00 mm, with most individuals having relatively small shells. The average SLs were 3.37 mm for S. javanica, 6.99 mm for S. laciniosa, and 5.60 mm for P. saccharina. This study is the first to document limpets on the rocky shores of Panay Island, providing baseline data on their ecology in the Philippines. Continued field monitoring and studies on population and reproductive biology are recommended to further understand the dynamics of these limpet populations.

Plastic pollution is a ubiquitous contemporary problem that demands to be addressed with urgency. Microorganisms that can degrade plastics may hold the key to resolving this problem by providing genetic and metabolic pathway knowledge on plastic degradation. In this study, soil samples were taken from Bago City Sanitary Landfill in Negros Occidental to isolate bacteria capable of degrading plastic pollutants. For 60 days, 5 bacterial isolates were cultured in minimal medium with pieces of UV- and autoclave (AC)-sterilized PET films. After 60 days, the film reduction analysis showed that isolate PT1 significantly degraded 9.29% of the UV-treated PET films when compared with the control, uninoculated PET films. Through molecular and biochemical characterization, the isolate was identified as Rhodococcus gordoniae PT1. The other bacterial isolates that showed growth on minimal medium with plastic as the sole carbon source were identified as Acinetobacter wuhouensis, Acinetobacter bohemicus, and Streptomyces ruber. The scanning electron microscopy analysis revealed the presence of structural changes, such as cracks and holes, on the bacteriainoculated films, indicating plastic degradation. The ability of these bacteria to degrade plastic provides a foundation for bioremediation, green chemistry, and bioengineering, offering a potential solution for eradicating tough pollutants from the environment. However, the potential pathogenicity of certain isolates needs careful considerations before applying these bacteria for bioremediation and bioengineering. Finally, this is the first study to identify plastic-degrading bacteria in Bago City, Negros Occidental, and the first to describe the plasticdegrading potentials of the identified species.

A study was conducted to estimate the carapace width (CW)-total body weight (TBW), CW-carapace length (CL) and CW-carapace depth (CD) relationships, sex ratio (SR) and relative condition factor (Kn) of the blue swimming crab Portunus pelagicus (Linnaeus, 1758) caught in the municipal waters of Tolosa, Leyte, Eastern Visayas, Philippines. Based on the carapace width and weight data, both female and male P. pelagicus exhibited a positive allometric growth pattern (b>3). The sex ratio of males and females was 1:2.32, where the number of females was significantly higher than males. The SR suggests that the catch of entangling nets during the sampling period was female-favored. On the other hand, a good state of well-being is suggested for both sexes given the Kn values of more than 1. The results of this study may serve as baseline information that could be helpful in the assessment of the current status of the P. pelagicus stock in the area. The morphometric characteristics and relationships may also serve as references in the field of fishing gear technology, particularly in the development or improvement of fishing gear design suited to the local stock of P. pelagicus in specific fishing areas.

Biodiesel is conventionally produced by alkali-based transesterification, which is limited by the presence of water and the free fatty acid content of oil feedstock. This study investigated the potential of metformin (1,1-dimethylbiguanide) as an alternative organic base catalyst for the transesterification of coconut oil with methanol. Two parameters were considered in this work, the catalyst loading and the amount of water in the feedstock. When no water is present in the feedstock, metformin showed a significant FAME yield of 55 ± 8% at 1.0% w/w catalyst/oil. Increasing the amount of metformin to 2.0% w/w significantly increased FAME yield to 71 ± 4%. In the presence of water (5.0%, w/w water/oil) however, the catalytic performance of metformin was practically lost, with FAME yields of only 5.5 ± 0.3% (1.0% w/w catalyst/oil) and 2.6 ± 0.4% (2.0% w/w catalyst/ oil). Overall, metformin showed the ability as a catalyst for the transesterification of coconut oil with methanol. However, its efficiency is limited only to conditions where the water level in the feedstock is minimal.

A flexible method for detecting system-wise outliers is presented. This approach attempts to simplify the detection of anomalous observations without relying on large datasets and complicated statistical modeling techniques. The method utilizes the leave-one-out method, similar to cross-validation technique in data resampling. Using this approach, observations are iteratively removed and a measure of variability is recalculated in each iteration. By doing so, the influence of each observation is evaluated in the data. Results of the simulation study show that this new method adequately recognizes anomalies in several data scenarios while minimizing incorrect detections. The method worked particularly well in data scenarios with high number of time points and low to moderate variability. On the contrary, the method showed weak performance when applied to datasets with low number of time points and very high variability. The proposed method was also applied to detect irregularities in regional fisheries production in the Philippines. Upon visual validation, results show that the new method was able to detect irregularities in the production data, such as trend and extreme shocks.

The cephalopod fisheries of the northern Sulu Sea based on Malalison Island, Culasi and in Tibiao, Antique, Philippines were monitored over a period of two years from April 2018 to March 2020, where catch (kg), species caught by gear, and fishing effort, were recorded daily in situ from a fixed and representative number of fishers. From these, catch, corresponding value, and fisher income were estimated. Of the three gears, the jigger fully (100%) targets cephalopods, while spearfishing catch fish slightly more than cephalopods. A total of five cephalopod species are exploited by the fishery i.e., two squids (Sepioteuthis lessoniana & Sthenotheuthis oualaniensis), one cuttlefish (Sepia latimanus), and two species of octopods (Callistoctopus nocturnus, and Octopus cyanea). Of these, the octopod species dominated the catch (71%) with S. lessoniana comprising the least (2%). Hook and line showed the highest catch (41.98%) of all gears, responsible for catching the two octopod species the most. Annual fisher income proved to be highest (annual mean PhP 54,508.84 yr-1) among those employing jiggers to exploit S. oualaniensis, the most expensive (PhP200 kg-1) species. The fishers’ annual income may not be much, but is augmented by other forms of fishing, specifically gleaning. Studies on these species’ population biology (age, growth, and mortality) and reproductive biology are necessary to further elucidate the level of exploitation towards ensuring their sustainable utilization.

The oil spill from M/T Solar I on August 11,2006 off southern Guimaras, Philippines released over two million liters of Bunker C industrial fuel. Visibly affected were the highly vulnerable mangroves. Spilled oil were stranded and settled in the shores affecting mangrove trees, saplings, and wildings; and including the associated resident fauna. The effect of oil spill in mangrove can be acute, secondary, and chronic and this paper focused only the acute effects of oil on the the affected mangrove flora in the affected sites in Guimaras. Specifically, the study (a) identified true mangrove species affected; (b) described the community structure; and (c) mapped the degree of oiling and areas with defoliated mangroves. The assessment was conducted on August 19 to November 18, 2006 for community structure analysis in 14 oiled sites, namely; Brgys. Dolores, Tando, Lucmayan, San Roque, La Paz (Taklong Island National Marine Reserve), Cabalagnan, Igdarapdap in Nueva Valencia; Brgys. Algeria, Sabang, Sebaste, San Isidro, Bubog in Sibunag; Igcawayan and Sebario in San Lorenzo. Two unoiled mangroves (reference sites) were also surveyed in Brgys. Getulio, Buenavista; and Lawi, Jordan. In terms of floristic composition, areas included in this assessment had 29 true mangrove species representing 14 families, or about 83% of the total number of know Philippines mangrove species. The highest floristic composition was record in Taklong Island National Marine Reserve (TINMR), in La Paz with 26 species. The most frequently occurring species were Avicennia marina, Rhizophora apiculate, R. mucronata, R. stylosa, and Sonneratia alba which occurred in 15 sites (93.8%) and they were also the dominating species with 66.66, 52.02, 27.48, 30.72, and 50.01 relative dominance respectively. Large-sized trees were found in Sebario, Igdarapdap, and Bubog with 13.31, 12.51, and 10.55 cm diameter at breast height respectively. Stand basal area ranged from 1.96 m² ha^-1 in Sebaste, to 56.36 m² ha^-1 in Bubog. The presence of large-sized S. alba in Bubog contributed greatly to its stand in basal area while relatively young or generating mangroves composed the stand of the latter. Densities per plant category vary widely per site. Wilding density was highest in Dolores with 49,567 individual ha^-1 and lowest in Tando with 700 individual ha^-1 ; sapling density was highest in Dolores with 2900 individual ha^-1 and lowest in San Isidro with 659 individuals ha^-1 ; and tree density was highest in TINMR with 3,983 individual ha^-1 and lowest in Sabang with 783 individual ha^-1 . Species diversity was highest in Sebaste (H’ = 1.088) and lowest in Dolores (H’ = 0.497). This high diversity is mainly attributed by the absence of the dominant species. The acute effects during the three month assessment involved the massive death of mangroves in Lucmayan, Bagatnan and Alman Sur which accounted to 0.932 ha. However, the remaining stranded oil in the mangrove area will continue to be a source of stress that cause chronic effects that are observed in a continuous and regular monitoring of the areas affected.

Mangrove forests of Guimaras were affected by M/T Solar oil spill on August 11,2006 releasing more than two million liters of Bunker C industrial fuel. Acute and lethal damage to these mangroves was assessed in the field and from aerial photographs. The study (a) measured the heights and extent of oil bands on trees, saplings, and wildings; (b) determined the percentages of oiling and mortality by plant category; and (c) determined the percentages mortality by species. Field assessment was conducted on August 19 to November 18, 2006 in 14 oiled and two unoiled sites. Mangroves surveyed in Nueva Valencia were all coated with oil except Dolores and Igdarapdap where only traces of oil were observed. The sites in Sibunag and San Lorenzo had only traces of oil painted on trunks, roots or leaves. Oil levels among trees ranged from 0.1-1.2 m in height (13.43% of the tree height coated with oil) and highest in Tandog Island and Lucmayan in Nueva Valencia. The same degree of oiling among saplings and wildings were observed among sites except that a patch of reforested area in Alegria, Sibunag was heavily coated that reached up to 0.4 m for saplings and 0.3 m for wildings. The sites within La Paz had the highest percentage of oiled trees (74.4%) and saplings (72.9%), while Cabalagnan had the highest percentage of oiled wildings (65.5%). Total area of dead mangroves accounted to only 0.932 ha distributed in Sitio Bgatnan, Lapaz (0.490 ha), Sitio Tuguisan, Lapaz (0.008 ha), and Panobolon (0.389 ha) all in Nueva Valencia. Areas with massive death of mangrove particularly trees were primarily characterized by a low hydrodynamic, tidal flushing is minimal thus leading to a delay in oil removal by natural processes. In Tandog Island, defoliated mangrove saplings and wildings were also observed, albeit very few in number and occurred sporadically. Overall species mortality was only 0.97%. Saplings had the highest with 1.60%, trees had 1.44%, and wildings had 0.47%. This low mortality among wildings is attributed by their viviparous nature that allowed them to survive in oiled sediments up to the point where food reserves stored in propagules were exhausted, where upon the plants died. Within sites, Lucmayan had 12.88% tree mortality, while Sitios Bagatnan and Tuguisan both in La Paz had 11.11% and 4.96% respectively. Saplings’ high mortality was observed in Sitio Bagatnan with 8.20%, while that of wildings was in Tandog Island  with 7.41%. Among the 29 species affected, only five species showed mortality: Avicennia marina (0.03%), Phizophora apiculate (0.16%), R. mucronata (0.26%), R. stylosa (0.48%), and Sonnerratia alba (0.04). Massive death were concentrated only in the inner part of the forest stretching towards the terrestrial margin while the outer fringe remained intact and often had one or two surviving trees along the seaward margin.

Many tropical environments areas are being heavily disturbed by human activity such as the marine environment. They have been a subject to contamination by organic pollutants from a variety of sources including accidental oil spills. On August 11,2006, M/T Solar I chartered by Petron sunk off the coast of Southern Guimaras released more than two million liters of Bunker C oil into the sea and affected diverse coastal habitats and ecosystems with considerable environmental damage. There is a little information on the effect of disturbance on fungi in tropical coastal ecosystems such as sandy beaches and mangroves which are habitats distinctive to the tropics. This study, therefore, examined the effects of the oil spill on the fungal diversity and density among the contaminated sites in the southern part of the island of Guimaras, Philippines within two months after the spill. The initial assessment was conducted on October 11, 2006 at eight sites were selected composed of six oil-contaminated sites and two from in-contaminated areas that served as control. Samples obtained were composed of one beach water sample and three soil samples. Yeasts and filamentous fungi were examined by macroscopic and microscopic observation of colonies. Identification was based on available keys and monographs. Majority of species isolated were mitosporic and typical soil fungi which are terrestrial in origin but are considered as facultative marine fungi. There are more fungal isolates at oil-contaminated sites than un-contaminated sites at 23 and 13 species, respectively as well as a higher Shannon Index of Diversity (H`) at 1.248 and 1.039, respectively. Among the filamentous fungi, nine genera were represented by Aspergillus, Aureobasidium, Cladosporium, Memnoniella, Monilia, Mucor, Penicillium, Pestalotia and Sporothrix. There was allow index of similarity of species composition between oil-contaminated and un-contaminated sites as shown by Jaccard’s coefficient of similarity (J = 0.40) and Sorensen coefficient of similarity: C = 0.57. All samples from oil-contaminated sites yielded a higher diversity and evenness of fungi compared with un-contaminated sites based on the Index of Diversity consistent with the overall trend of fungal occurrences. It appears that most of the oil-contaminated sites particularly beach and mangrove surface soil samples at Taklong Island exhibited a much higher fungal load compared with the un-contaminated sites that could possibly be attributed to the presence of oil in areas that favored their growth. This study provided some evidences on the short-term impacts in terms of change in fungal assemblages and density. Although the report is not conclusive considering the absence of pre-spill data and variability between months or year, the evidence indicates that there was disturbance brought about by the oil. Thus, the need for a long-term monitoring program to examine the effects of oil in these areas to determine recovery and re-instatement of normal fungal flora.