The Journal of Environmental Science and Management (JESAM) (ISSN 0119-1144) is Web of Science-indexed journal that is produced semi-annually by the University of the Philippines Los Baños (UPLB).

It features research articles, theoretical/conceptual papers, discussion papers, book reviews, and theses abstracts on a wide range of environmental topics and issues.

Current Issue
Volume 26 Issue Number 2 (December 2023)

From Plastic Pollution to Sustainable Solutions: Exploring Reusable Bag Intentions in Jakarta, Indonesia

Roozbeh Babolian Hendijani

Abstract: Despite public awareness of how dangerous plastic bags are, people still use them excessively in Indonesia. This research is conducted to determine customers’ intention to use reusable bags and to find out whether there is a significant difference between genders in terms of intention to reuse bags. Data were collected through 150 self-administered questionnaires distributed randomly to people in modern supermarkets and minimarkets around Jakarta. Statistical analysis, such as hierarchical regression, independent sample t-test, and descriptive analysis were used to analyze the data. Attitudes, convenience, and environmental concern have a significant relationship with customers’ intentions. There was no significant difference between genders in terms of their intention. This research sheds light on a nuanced aspect of sustainable behavior, specifically the role of gender in the intention to reuse bags. Its originality lies in the context of Indonesia and the analysis of gender dynamics. The implications of this study extend beyond academia, offering practical guidance to marketers, retailers, and policymakers seeking to promote environmentally conscious consumer behavior and reduce plastic bag consumption.

Waste Management Practices of Dairy Buffalo Farmers in Nueva Ecija, Philippines

Estella P. Valiente, Marisa J. Sobremisana, Dante Gideon K.Vergara, Josefina T. Dizon

Abstract: Effective waste management in dairy buffalo farming is vital to ensure the health and productivity of a farm and its farmers, as well as to minimize negative environmental impacts. This study examined the waste management practices of dairy buffalo farmers in Nueva Ecija, Philippines in relation to their socio-economic status and farm profile. Fifty-nine dairy buffalo farmers were interviewed face-to-face using pre-tested semi-structured questionnaires to gather data on their socio-demographic and economic profiles, farm profiles, and waste management system. Principal Component Analysis and binary regression were used to determine correlation between socio-economic status and farm profile with their manure management systems. Eighty percent of the respondents practiced stockpiling while 12% practiced vermi-composting. The liquid waste is disposed of via open channels going to rice fields, rivers, creeks, irrigation canals, forage areas, or vacant lots. The non-biodegradable farm waste is either buried, burned, thrown in a vacant area, reused, sold or given to garbage collectors. The regression model revealed that the significant determinant of manure management system was animal holding (p<0.05) which indicates that as the animal holding of the dairy farmers increased by 1 unit, there was a .23 increase in the probability that the dairy farmers will practice stockpiling. The agencies concerned need to intensify efforts to disseminate suitable, cost-effective, efficient and sustainable interventions related to waste management for dairy buffalo farms.

Antarctica and the West Philippine Sea: Exploring a “Cold” Policy Option to Address “Hot” Contentions to Philippine Rights in its Western Maritime Domain

Ben S. Malayang III, Florin T. Hilbay

Abstract: This research discuss a policy option for the Philippines to reduce the intensity of “hot” disputes over its sovereignty and sovereign rights to protect and manage the fisheries and other resources in the West Philippine Sea (WPS). (The authors define “hot” disputes as contentions involving belligerent assets used to assert disputants’ interests, and which could turn lethal; this, in contrast to “cold” disputes which those with no disputant using belligerent assets to assert its interests.) gleaned an option from three lessons learned from the Antarctic Treaty System (ATS): shared ecological interests are given greater emphasis than any nation’s political interests; creating a scientific community and an environment of free exchange of scientific knowledge undergird common benefits to the Treaty’s Contracting Parties and the world at large; and a military option to settle disputes does not always provide the best returns to disputing countries’ efforts. The Philippines may continue with its current WPS policy of containing the disputes or take the option of opening a global science and conservation program in the West Philippine Sea along the model of the ATS, to strengthen and sustain the seascape’s heritage value to Filipinos and others in the larger South China Sea (SCS) basin and beyond.

Forecasting of Monthly Closing Water Level of Angat Dam in the Philippines: SARIMA Modeling Approach

Allan T. Tejada, Jr., Mara Sherlin D. Talento, Lara Paul A. Ebal, Celine A. Villar, Bernadette Lois V. Dinglasan

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Abstract: The operation and management of Angat Dam as a multipurpose dam for domestic, irrigation, power, and flood control purposes, is governed by the operation rule curve of dam water level. This study was conducted to understand the behavioral pattern and to provide short-term forecast of the monthly closing water level of Angat Dam using the Seasonal Autoregressive Integrated Moving Average (SARIMA) model, considering the data from January 1990 to December 2021. Series decomposition revealed the absence of an overall trend component but the presence of seasonality in the dataset. An almost perfect partial correlation between the closing water level of a certain month and the preceding two months’ records was observed in the correlogram. Different SARIMA models were evaluated and subjected to diagnostic checking and based on minimum Akaike Information and Bayesian Information criteria, SARIMA (1,0,1) (0,1,1)12 model with estimated coefficients of φ1= 0.8050, θ1 = 0.2278, and Θ1= -0.999 was selected to forecast the monthly closing water level of Angat Dam. The model fits with a root mean square error (RMSE) of 4.79 meters, mean absolute error (MAE) of 3.45 meters and coefficient of determination (R2) of 0.93. On average, the forecast water levels of the best SARIMA model are off by around 1.8% of the actual value.

Indications of Enhancement of Reef Fish Community Richness at Selected Coral Rehabilitation Sites in the Philippines

Badi R. Samaniego, Rico C. Ancog, Maria Hildie E. Nacorda, Homer B. Hernandez, Maria Christina G. Corales, Annelyn Gem L. Balatayo

Abstract: Reef deterioration is a chronic issue that has persisted over the past decades. Much effort has been invested into research and development of reef rehabilitation technologies. Reef rehabilitation via coral fragment transplantation was initiated in 2012 at selected areas across the country. Assessments of its impacts on the diversity of reef fishes in Batangas, Tawi-Tawi, Aklan and Bohol in the Philippines using the fish visual census technique were conducted in 2017, five years after coral transplantation. Significant positive results were found at the treatment sites in Mabini, Batangas and in Bongao, Tawi-Tawi. Mean fish species richness were 56 and 43 species 250 m-2 at the treatment and control sites in Batangas, respectively, and 74 and 48 species 250 m-2 at Bongao, Tawi-Tawi. In contrast, the numbers of fish species at the control sites in Aklan and Bohol were slightly higher, but these were not statistically significant. Coral transplantation can potentially enhance fish diversity; but the effects of coral transplantation on fish communities may be difficult to demonstrate and detect. Sound scientific design and efficient application of the technology are needed to unambiguously present their potential benefits. Issues, challenges, and recommendations to advance the conduct of such reef enhancement initiatives are discussed.

Global Warming Potential and Life Cycle Cost of Conventional and Potentially Low-Carbon Philippine Swine Production Systems

Rex B. Demafelis, Anthony B. Obligado, Hernando F. Avilla, Bernadette T. Magadia, Angelica Ariel U. Mawili, Eros Paul V. Estante

Abstract: This study identified and evaluated conventional and low-carbon swine production systems through a review of literature and visits to commercial farrow-to-finish swine farms in the Philippines, aiming to recommend a swine production system that cost-effectively reduces GHG emissions. Parameters assessed were greenhouse gas (GHG) emission, carbon and payback period, and return on investment through conduct of life cycle assessment. The identified conventional technologies are open-sided housing system, slatted flooring, modified manual feeding system, nipple drinker, and scrapper and power sprayer as cleaning systems. The identified low carbon technologies are low protein swine feed formulation supplemented with amino acids and partial substitution of soybean meal with Protein-Enriched Copra Meal (PECM), open-sided housing with cemented flooring, manual feeding system, bite ball valve, scrapper combined with power sprayer as cleaning system, and biogas digester as manure management system. These entailed a GHG emission reduction potential of 31.93% in reference to the conventional system. The low carbon production system accounted for higher return on investment of 36.75% and shorter payback period at 2.72 years, compared to the conventional system that yielded 19.96% and 5.01 years, respectively. The identified low carbon swine farm production system can be a cost-effective alternative to the conventional production system.

Recovery of Coconut Trees from Scale Insect Infestation with Salt and Trichoderma Microbial Inoculant (TMI)

Virginia C. Cuevas, Merdelyn T. Caasi-Lit, Ireneo L. Lit, Jr., Marnelli S. Alviola, Charina Gracia B. Banaay, Artemio M. Salazar

Abstract: This study showed the role of Trichoderma Microbial Inoculant (TMI) and salt in the fast recovery of mature coconut trees damaged by coconut scale insect, Aspidiotus rigidus Reyne, and in the growth of coconut seedlings. Four treatments with three replicates were laid out in a randomized complete block design. Treatments made were: T0 with 0 fertilizer, 0 TMI; T1 with full dose N, P, K fertilizers, NaCl, 0 TMI; T2 with 1⁄2 dose fertilizers + NaCl, + TMI; and T3 with NaCl + TMI. Fertilizers and salt were split delivered in T1. Ten 1-m tall coconut seedlings (Laguna Tall Variety) per replicate treatment were interspersed with the mature trees in each block. About 25 g TMI per tree and 15 g TMI per seedling were applied together with fertilizers. Numbers of green, yellow, and brown leaves, inflorescences, and fruits produced per mature tree were monitored for 27 months. New and mature green leaves were counted as measure of coconut seedling growth. Mature trees in T3 had significantly higher number of green leaves and fruits compared to other treatments. T3 seedlings had significantly higher number of mature green leaves than those of other treatments. Both mature trees and seedlings in T3 exhibited the fastest growth. These results highlighted the importance of salt and TMI for productivity of coconut trees and seedlings.

Catch of Otolithes ruber (Bloch & Schneider, 1801) under Varying Fishing Practices of Municipal Fisherfolks in San Miguel Bay, Philippines

Emerson L. Bergonio, Maria Victoria O. Espaldon, Hildie Maria E. Nacorda, Rico C. Ancog

Abstract: Tiger-toothed croaker or Otolithes ruber (Bloch & Schneider 1801) is native to San Miguel Bay in Bicol, one of the most productive fishing grounds in the Philippines. Locally known as “abo”, it is one of the major fish catch in the bay and its processing is a seasonal livelihood among coastal villages that commands high market price. With the present state of area, this study aimed to provide information on O. ruber catch trend under the different fishing practices among municipal fisherfolks. On-board surveys and observations (fishing trips) were conducted from the selected barangays of the seven municipalities around the Bay, which were attended by fisherfolk who have been into fishing activity for a long time. The morphometric characteristics of the fish in terms of size (lengths and weights), sex type, and sexual maturity were assessed. Fisherfolks prefer to perform fishing activities applying fishing methods such as “timbog” (“tupak”), “patalang” and “hugos”, if the water is turbid while others believed in the phases of the moon wherein better catch is experienced when the moon is on its first or last quarters. Fishing trips demonstrated that fisherfolks used bottom-set gillnets and commonly explored the middle to the mouth of the Bay off the municipalities of Mercedes and Siruma. From the 162.69 kg total catch during the 22 fishing trips, 31.49% or 51.22 kg of which were O. ruber caught largely from Mercedes, Calabanga and Cabusao areas. Mercedes employed the “patalang” method while the other two employed “timbog” method. Out of 434 O. ruber samples, 222 females and 212 males, having 1:1 ratio, were identified with TL of 19.14 + 0.11 cm and body weight of 70.76 + 1.46 g. Moreover, macroscopic analyses of gonads revealed that maturity stages of females ranged from mature to ripe or spawning while most males are already mature and gravid with some developing virgin.