Recent Submissions

  • Status of coral reefs, butterflyfishes, and benthic macro-invertebrates in Araceli and Dumaran, Palawan, Philippines

    Aludia, Geofrey; Mecha, Niño Jess Mar; Cornel, Anton Rey; Acebuque, Ace Niño Andrew; Rodriguez, Jomil; Miguel, Jona; Menardo, Ian; Dolorosa, Roger (2022-12-16)
    The Palawan Scientist
    As a major fishing ground in Palawan, the reefs in the municipal waters of Araceli and Dumaran are continuously facing anthropogenic and climate-related threats. Hence, to provide information about the reef conditions, surveys were undertaken in three sites of each municipality as the basis for management. Data collection used the C30 method where a 75 m x 25 m sampling area was established at the upper reef slope (2-5 m deep) of each site. Substrates were photo-documented at predetermined random positions and the photos were processed using Coral Point Count with excel extension software (CPCe) to determine the percent substrate categories. Identification and counting of butterflyfishes and benthic macro-invertebrates were also undertaken. The hard-coral cover (HCC) ranged between 27.10 and 53.88% (fair to very good) for Araceli and 22.66 and 48.62% (fair to good) for Dumaran. The number of species and density of butterflyfishes largely varied across reefs. The benthic macro-invertebrates only included the blue Linckia starfish and giant clams. The current reef condition calls for urgent management actions.
  • Notes on the first record of Tridacna noae (Röding, 1798) (Cardiidae: Tridacninae) in Palawan, Philippines.

    Ecube, Krizia Merly A; Villanueva, Elmer G; Dolorosa, Roger G; Cabaitan, Patrick C (2019)
    The Palawan Scientist
    The first record of Tridacna noae in the province of Palawan, Philippines was documented on June 21, 2018, at Paraiso Resort, Albaguen Island, Port Barton in the municipality of San Vicente. The single specimen measured 4.5 cm in shell length and was partly buried in a massive coral rock. The mantle edge of the species is lined with teardrop-like patches with white margins. This recent finding is an addition to the seven previously reported giant clam species in Palawan and confirms new sighting location in the existing geographic range. The habitat of the species is a semi-protected cove, about 1 m deep at high tide, with massive coral rocks generally covered with the seaweed Sargassum spp. Potential threats include the shading effects of macro algae and the constant presence of tourists visiting the resort who might accidentally step on the clams. Buoy demarcation to exclude the area from disturbance may help protect the species and other boring giant clam species. Continued assessment may provide information on the status of T. noae in Palawan and in other parts of the country.
  • Road mortality of freshwater turtles in Palawan, Philippines

    Bernardo, Alejandro A Jr (2019-07-01)
    The Palawan Scientist
    The impact of road mortality on freshwater turtle populations on a global scale could be significant enough to cause the extinction of sensitive species. Essential data on roadkill abundance, composition, spatial patterns, and temporal distribution is needed for crafting mitigation strategies. To provide such information, a survey was conducted along the highway section (67 km) connecting Aborlan and Puerto Princesa City in Palawan, Philippines. Collection of data was done four times a month from January 2010 to December 2015. A total of 127 road-killed turtles belonging to two species of the Geoemydidae family were recorded, 102 (80.3%) of which were classified as the Southeast Asian Box Turtle (Cuora amboinensis) and 25 (19.7%) were identified as the Asian Leaf Turtle (Cyclemys dentata). The increase in road traffic noticed during the survey period possibly caused the corresponding increase in the roadkill counts 0f C. amboinensis, which is a more common species. Concurrently, the decline in the road-kill counts of C. dentata may indicate a severe drop in the population of this less common species. Roadside habitat types, time of the day, and presence of water bodies are found to be important predictors of road-killed turtles. High densities of road-killed turtles clustered in short segments of the road which identified as hotspots. Effective mitigating measures to curve down the impact of road mortality on turtle populations must be implemented and focusing the conservation strategies along the hotspots is considered an efficient and practical option.
  • Elysia leucolegnote (Opistobranchia: Sacoglossa) Jensen 1990, a new record for the Verde Island Passage, Philippines

    Sanchez-Escalona, Katherine P (2019-07-01)
    The Palawan Scientist
    Aggregations of Elysia leucolegnote were observed from Silonay Mangrove and Ecopark, Calapan, Oriental Mindoro, occurring on mudholes with water retained from retreating tide waters. The individuals in the aggregations has white markings on the parapodia and the rhinophores, and yellow marking on each quadrant of the body. This is the first report of the occurrence of the mangrove-associated species from the Philippines which increased the number of Elysia species records to 10 species.
  • Spatial and temporal distribution, Size composition, and Abundance of Oval squid, Sepioteuthis lessoniana (Lesson 1830) in the coastal waters of Bolong, Zamboanga City, Philippines

    Samson, Jesus Rolando A (2019-07-01)
    The Palawan Scientist
    The study was conducted in the coastal waters of Bolong, Zamboanga City, Philippines purposely to determine the spatial distribution of Sepioteuthis lessoniana in relation to the depth of water and temporal distribution in relation to lunar phase using size composition and catch per unit effort (CPUE) data. Two sampling stations were established, namely, shallow-water station (Station 1) and deep-water station (Stations 2). Twenty units of squid traps were utilized in the study; ten of which were set in Station 1 and the other ten in Station 2. The traps were constructed using bamboo and green polyethylene netting. Instead of bait, coconut spikelet was placed inside the trap to lure squids. A motorized banca was used to set and haul the traps in the two sampling stations. Although hauling was done daily, sampling is scheduled only 12 times a month with three samplings per lunar phase. Catches were segregated according to sampling stations and lunar phases. Results of the study revealed that the squids caught in deeper waters were significantly larger than those caught in shallow waters, and that females dominated the shallow waters while males dominated the deeper waters. Furthermore, the catch during Full Moon was significantly higher than the catch of the other three lunar phases (p<0.05) with highest CPUE recorded in Station 2 during Full Moon (0.352 kg trap-1 day-1).
  • Molecular characterization and tissue distribution of cysteamine dioxygenase (ADO) in common carp Cyprinus carpio

    Gonzales-Plasus, Maria Mojena G; Haga, Yutaka; Kondo, Hidehiro; Hirono, Ikuo; Satoh, Shuichi (2019-07-01)
    The Palawan Scientist
    The low production of hypotaurine from cysteine but a significantly high taurine deposition in common carp led to the hypothesis that this species utilizes an alternative pathway other than the cysteine sulfinic acid pathway. Cysteamine pathway is common in mammals but not in other animals such as birds, invertebrates, and fishes. The cloned cysteamine dioxygenase (ADO) cDNA in common carp consists of 790 nucleotide bases with 260 deduced amino acid sequence. The conserved domain is the DUF1637 which has a conserved tyrosine and cysteine residues and the presence of three predicted N-glycosylation sites. Phylogenetic analysis using neighbor joint method indicated that ADO in common carp branched after Sinocyclocheilus rhinocerous. ADO was expressed in hepatopancreas, brain, gill, intestine, and muscle of common carp. The hepatopacreas had a significantly higher gene expression level than the other organs examined. The present results suggest that ADO is present in common carp.
  • Backyard farming of tilapia using a biofloc-based culture system

    Caipang, Christopher Marlowe A; Avillanosa, Arlene L (2019-07-01)
    The Palawan Scientist
    The pressures brought about by the increase in human population resulted in the rapid expansion of the food production industries including aquaculture to provide the nutritional requirements of the growing population. As aquaculture operations intensify, there is also an urgent need to preserve the environment; hence, all activities must be carried out in a sustainable way. The use of the biofloc technology (BFT) in aquaculture addresses these issues on restrictions on the usage of water and land as well as matters concerning sustainability of the production. BFT is a technique that maintains optimum water quality in the aquaculture system by manipulating the carbon and nitrogen ratios in the system. This optimum ratio favors the growth of heterotrophic bacteria that contribute in maintaining good water quality and at the same time provide sources of natural food for the cultured fish or crustaceans. In this review, the mechanisms of the biofloc technology particularly in the production of tilapia in freshwater systems are discussed. Moreover, some of the intrinsic advantages of this technology are highlighted in the context of developing and supporting backyard aquaculture of freshwater tilapias as a means of providing the food demands of the population in rural communities and as source of income for the marginalized small-scale fish farmers.
  • Heavy oil degrading Burkholderia and Pseudomonas strains: insights on the degradation potential of isolates and microbial consortia

    Bacosa, Hernando P; Inoue, Chihiro (2020-07-01)
    The Palawan Scientist
    Bacterial strains were isolated from heavy oil degrading microbial consortia enriched from mangrove sediment. Among the 60 distinct isolates that formed colonies on heavy oil as a sole carbon and energy source, Pseudomonas sp. T2B and Burkholderia sp. T2C showed the best growth in heavy oil and in various aliphatic and aromatic hydrocarbons. The two isolates were tested in their abilities to degrade heavy oil. At 1% oil concentration, T2B and T2C degraded 19.6% and 16.7% of heavy oil within 21 days, respectively. These values were significantly lower than that of the source consortium T2, which degraded 24.2% of the oil. This indicates that the consortium is more superior in degrading heavy oil than any of the isolates. The isolates can be used for biodegradation studies and can be utilized in producing an effective microbial consortium for bioremediation applications.
  • Growth and lipid levels of Tetraselmis tetrahele and Nannochloropsis sp. cultured under commercial fertilizers

    Gonzales-Plasus, Maria Mojena G (2020-07-01)
    The Palawan Scientist
    Microalgae are aquatic photosynthetic organisms that contain high amounts of lipid and are potential sources of biofuels as well as feed additives for aquaculture. This study analyzed the growth and algal lipid content of two microalgae species (Tetraselmis tetrahele and Nannochloropsis sp.) using commercial fertilizers and nutrient enrichment. The samples were cultured for 5 days in 1 L dextrose bottles fertilized using Tongkang Marine Research Laboratory (TMRL) enrichment media, inorganic fertilizers such as 14-14-14, and a combination of 14-14-14 and 21-0-0. The relative growth rate of two algae were measured by computing the k value while the lipid components were extracted using the Bligh and Dyer Method, and the lipid content of each sample was determined using the gravimetric method. The use of 14-14-14 fertilizer produced the highest growth rates (k=1.810) and lipid composition (14.789%) for T. tetrahele. By contrast, Nannochloropsis sp., grew well under TMRL enrichment media (k=9.708), and the use of 14-14-14 fertilizer resulted to high lipid content (5.000%).
  • Length-weight relationship of marine fishes from Palawan, Philippines

    Palla, Herminie P; Pagliawan, Honorio B; Rodriguez, Edwin F; Montaño, Bernaldo S; Cacho, George T; Gonzales, Benjamin J; Bonnell, Carey; Fowler, Tom (2018-07-01)
    The Palawan Scientist
    The parameters of the length-weight relationships (LWR) of fishes are the primary variables applied to estimate the biomass of reef fishes in situ. Estimates of reef fish biomass using fish visual census survey in the Philippines still utilized the values of LWR parameters derived from the results of studies conducted abroad due to paucity of local information. This paper presents the first comprehensive records of the LWR of marine fishes from the West Philippine Sea and the Sulu Sea, western Philippines. Data were collected between 1998 and 2014 using various artisanal and commercial fishing gears. A total of 11,539 specimens covering 33 families, 59 genera and 87 species were investigated. The allometric coefficient b varied between 2.140 (Gnathanodon speciosus) and 3.410 (Taeniura lymma) with the mean of 2.8400.25. The values of r 2 ranged from 0.521 to 0.996. This paper provides the first comprehensive information on the LWR of marine fishes from the western Philippines consisting of 15 new LWR values and 12 higher maximum lengths for online database.
  • Marine algae of the Sulu Sea islands, Philippines III. Taxonomic account of the Gracilariaceae (Rhodophyta)

    Liao, Lawrence M (2018-07-01)
    The Palawan Scientist
    The Cuyo Islands lie on the northern fringes of the vast Sulu Sea straddling between the westernmost Philippine island of Palawan and the central portion of the archipelago. A recent study revealed a high diversity of the benthic brown algae (Phaeophyceae) there. However, records of other algal groups like the green and red algae have been sporadic and few. This study is a survey of the representatives of the Gracilariaceae, a group of economically-important red algal species valued for its agar content. Collections were made by snorkeling and Scuba diving from shallow-water and subtidal habitats from 16 stations in six islands. Results revealed a total of five species of the Gracilariaceae distributed throughout the Cuyo Islands. As these species constitute a significant but untapped marine resource for commercial exploitation, the results of this survey will serve to provide useful baseline information for resource management, eventually contributing towards better livelihood generation and options in coastal villages.
  • Toxicity of dispersed oil on Gold–saddle rabbitfish Siganus guttatus fry

    Balisco, Rodulf Anthony T; Quinitio, Gerald F (2017-07-01)
    The Palawan Scientist
    The acute toxicity of dispersant Mardeus-455 added to water accommodated fractions (WAF) were evaluated in Gold-saddle rabbitfish Siganus guttatus fry after 72 h exposure under laboratory conditions. Mortalities of fry exposed to different concentrations of dispersed oil were recorded every hour for the first 6 h, every 3 h for the next 12 h, and every 6 h thereafter. Results showed that the higher the ratio of dispersant and WAF, the higher the mortality of the rabbitfish fry which may be due to the enhanced availability of polyaromatic hydrocarbons (PAH). The LC50 was computed at 3.692% of the oil volume. The application of dispersant in cleaning oil spills must be limited to reduce its harmful effect in the marine environment. Assessing toxicity of dispersed oil in fish fry may help understand the extent of environmental damage after cleaning oil spill using dispersant.
  • First record of the elusive Freshwater snapper Lutjanus fuscescens (Valenciennes, 1830) in Palawan, Philippines

    Jose, Edgar D; van Beijnen, Jonah; Calago, Solomon (2016-07-01)
    The Palawan Scientist
  • Antibacterial potential of crude extracts from sea cucumber Holothuria fuscoscinerea Jaeger, 1833

    Cayabo, Genese Divine B; Mabuhay-Omar, Jhonamie A (2016-07-01)
    The Palawan Scientist
    This study was conducted to determine the antibacterial potential of the crude extracts of skin, gonad, Cuvierian tubules, Polian vesicles and intestine of the sea cucumber Holothuria fuscoscinerea collected from Rasa Island, Narra, Palawan, Philippines. The antibacterial potential of the extracts was determined against Escherichia coli and Staphylococcus aureus using filter paper disc diffusion method with Tetracycline as the positive control and distilled water as the negative control. The analysis of variance (ANOVA) of the results showed significant differences in the effects of the treatments when tested against S. aureus and E. coli (p<0.05). Tukey’s test further proved that Polian vesicle was significantly highest in terms of antibacterial property among other extracts but not comparable to positive control against S. aureus. On the other hand, Tukey’s test showed that Cuvierian tubules and Polian vesicles were not significantly different from each other in terms of antibacterial effect but not comparable to tetracycline when tested against E. coli. The extracts from skin, gonad and intestine did not show inhibitory effect on the test organisms. T-test showed that E. coli and S. aureus were not significantly different in terms of susceptibility towards the treatments. Based on the results, extracts from Cuvierian tubules and Polian vesicles of H. fuscoscinerea are potential sources of antibacterial compounds.
  • Nesting incidence, exploitation and trade dynamics of sea turtles in Balabac Strait Marine Biodiversity Conservation Corridor, Palawan, Philippines

    Antonio, Rene Abdulhamed S; Matillano, Joie D (2016-07-01)
    The Palawan Scientist
    The study assessed the nesting incidence, threats to nesting habitats, exploitation and trade dynamics of sea turtles in the Balabac Strait Marine Biodiversity Conservation Corridor (MBCC). The most number of nests found belonged to the green sea turtle Chelonia mydas and only very few were of hawksbill sea turtle Eretmochelys imbricata. The shoreline vegetation was the most preferred nesting area, followed by beach forest and open beach. The eggs and meat of sea turtles in Balabac Strait MBCC are exploited for local consumption and trade. Information on trade route and local perception on conservation issues about sea turtles is also presented herein.
  • Composition, size and relative density of diatoms in the stomach of 4 to 75 day-old juvenile abalone Haliotis diversicolor (Reeve)

    Creencia, Lota A; Noro, Tadahide; Fukumoto, Makoto (2016-07-01)
    The Palawan Scientist
    The diatom biofilm that naturally grow on polyvinyl chloride plates serve as food of postlarva and juvenile abalone Haliotis diversicolor Reeve, called “tokobushi” in Japanese. Composition, size and relative density of diatoms in the stomach of 4, 7, 10, 13, 17, 21, 27, 35, 50 and 75 day-old tokobushi were evaluated to characterize their diatom intake. Stomach in glycol methacrylate resin was sectioned and examined under the light microscope, then analyzed using an image processing software. The diatoms present in the stomach of tokobushi were Thalassiosira, Melosira, Triceratium, Odontella, Asterionella, Licmophora, Thalassionema, Cocconeis, Navicula and Nitzschia. Only four varieties of diatoms were observed in 4 to 10 day-old tokobushi which coincided with initial feeding. The number and size of diatoms increased in 13 to 75 day-old juvenile, which were exhibited in its exponential growth pattern. The stomach of 4 to 13 day-old tokobushi contained small-sized diatoms (<67 μm) while both small and large-sized diatoms (>123 μm) were observed in 17 to 75 day-old juveniles. Higher relative densities (8.7 – 15.8 diatom/1000 μm2) of diatoms were documented in 4 to 10 day-old tokobushi while 17 to 75 day-old exhibited lower relative densities (1.2 – 4.2 diatom/1000 μm2). Generally, as young tokobushi increases in size, the diatom intake increases in composition and size but density decreases with increasing size of diatom ingested.
  • Water parameters of Pulang Lupa Lake, an abandoned open pit mine in Puerto Princesa City, Palawan, Philippines and its potential as bird watching destination

    Garagara, Lucila P; Baaco, Allaine T (2015-07-01)
    The Palawan Scientist
    Abandoned open pit mines when properly managed can be an important settlement and eco-tourism sites. The Pulang Lupa Lake – an abandoned mercury open mining pit in Puerto Princesa City supports a number of settlers and important wildlife. With limited information about its status, this study was conducted to determine the lake’s water quality and its potential for eco-tourism. Water physico-chemical parameters were within the permissible limits sets by the Department of Environment and Natural Resources for Class C water during the rainy but not in summer season. Water samples for both seasons were positive for total and fecal coliform. The lake serves as important source of fish for informal settlers and the presence of several bird species makes it a potential bird watcher’s destination. Information and education campaign among the residents around the lake and strategic environmental plans are needed for its sustainable utilization.
  • Notes on the presence of Manta alfredi in the Tubbataha Reefs Natural Park, Cagayancillo, Palawan, Philippines

    Aquino, Ma. Theresa R; Songco, Angelique M; Alarcon, Rowell C (2015-07-01)
    The Palawan Scientist
    In 2011, a review of 33 photographs of mantas taken at the Tubbataha Reefs Natural Park (TRNP), Cagayancillo, Palawan, Philippines revealed that most of the mantas photographed were clearly reef manta rays (Manta alfredi) with only one photograph of Manta birostris. Previously identified in surveys within the park as oceanic manta ray M. birostris, the presence of M. alfredi has never been established until now. Using various parameters, the pictures in the Tubbataha Management Office (TMO) database were reviewed and noted. The identification of M. alfredi was more consistently based on the presence of black marks located posterolateral to the last gill slits and between the rows of gill slits. The identification of the species was further validated by experts after viewing three photographs from the said database. This represents a new elasmobranch species record for the TRNP and, technically, for the Philippines as well. Furthermore, the confirmed presence of both globally significant species of manta rays should have a strong bearing on the conservation policies of the park as well as that of the country. Further research on population dynamics, structure and abundance is recommended. Contributing to global efforts to generate better understanding of the species through partnership with international organizations is also recommended.
  • Notes on the Gracious Sea Urchin Tripneustes gratilla (Echinodermata: Echinoidea) in Pag-asa Island, Kalayaan, Palawan, Philippines

    Balisco, Rodulf Anthony T (2015-07-01)
    The Palawan Scientist
    The Gracious Sea Urchin Tripneustes gratilla is one of the most heavily exploited sea urchins in the Philippines. However, knowledge about its status in Palawan especially in Pag-asa Island, Kalayaan is wanting. The study was conducted to determine the size structure, population density and test diameter-weight relationship of T. gratilla in Pag-asa Island, Kalayaan. Transect surveys at the intertidal area of the island revealed an average density of 3,500 ind.ha-1. The test diameter ranged between 2.6 and 8.8 cm, and body weight ranged between 8 and 248 g. Other than T. gratilla, four other echinoid species were recorded but in very less number. While it appears that T. gratilla is under exploited in Pag-asa Island, policies affecting its sustainable utilization are suggested.

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