Laguna Lake Research Articles

Effects of beta-benzene hexachloride in-ovo on the embryonic growth and development of domestic mallard ducks (Anas platyrhynchos domesticus L.)

Introduction Lake shellfish feed resources were found having 0.05 ppm heavy metal Cadmium but negative for organochlorine pesticides (OCPs) (Laguna Lake, Philippines), however golden apple snail (kuhol) from rice paddies were found having 0.03–0.08 ppm Cadmium and 0.01–0.02 ppm Endosulfan [1]. Surprisingly duck commercial feeds were also found having OCPs, like

Polychlorinated Biphenyls in Selected Sites in Pasig River and Laguna Lake in the Philippines Before and After a Big Flood Event Investigated Under the UNU East Asia Regional POPs Monitoring Project

This paper reports the results of the 2009 United Nations University (UNU) East Asia Regional Monitoring of the Coastal Hydrosphere Project implemented in the Philippines. The monitoring activity focused on the concentrations of 16 specific congeners of Polychlorinated Biphenyls in selected sites in Pasig River and Laguna Lake for two sampling periods in August and in November, 2009. The results show that the total concentrations of PCBs detected in the sampling sites in August increased during the November sampling from 0.9-12.2 to 6.1-32 ng/L in Pasig River and from 0.1-0.9 to 2.9-10.8 ng/L in Laguna Lake. The increase in PCB concentrations on second sampling is attributed to the increase in contaminated sediments in the river sites and to the overflow of contaminated water in the lake sites; both of which could have been caused by the flooding event that occurred in September 2009.

Limnological Analysis of Laguna de Bay Lake at Binangonan Freshwater Station: Its Implication to Plankton Diversity

Geographically located southeast of Manila, Laguna Lake is used for multiple resources such as fishery, irrigation, power generation and navigation. Recently, the lake has been considered as a source of potable water for Metro Manila. A Limnological study of the Lake was conducted to assess its present status and potential. Three sampling sites were considered in the identification of the plankton community. Plankton samples were examined at the University of Santo Tomas Biological laboratory. Plankton species were identified using the taxonomic key of Needham and Needham. The physicochemical characteristics of the water at the different sites were assessed. Temperature and pH were measured using an analytical radiometer, dissolved oxygen (DO) was computed, transparency was determined sing the secchi disc with a diameter of 26 cm; chemical oxygen demand (COD) was computed using the standard method. The results showed that sampling site 2 had the highest DO and COD. The phytoplankton Cyanobacteria like Spirullina major and Lyngbya limnetica dominated the lake. The green algae Chlorella vulgaris and Pediastrum spp. Were found to be distinct in the lake. Copepods (Copepoda spp.) are the zooplanktons observed. Laguna Lake (Binangonan Freshwater Station) has slightly basic water still suitable for aquaculture, recreation and industrial use. The lake is eutrophic. Keywords - algae, copepods, Laguna lake, limnological study, Physicochemical analysis, phytoplanktons, zooplanktons

Toxicological assessment of pesticides used in the Pagsanjan-Lumban catchment to selected non-target aquatic organisms in Laguna Lake, Philippines

Laguna Lake is the largest inland water resource in the Philippines and an important source of fisheries in the area. The Pagsanjan-Lumban catchment is the main freshwater input of the lake but contaminants resulting from agricultural activities within the catchment may impact fisheries. Laboratory-based acute toxicity data was generated on selected non-target aquatic species native to Laguna Lake for pesticides used in the catchment. Freshwater shrimp, Macrobrachium lar, were found to be the most sensitive species for the pesticides used in the areas surrounding the catchment compared to Tilapia sp. embryos, newly hatched Tilapia and 22mm Tilapia fingerling. Of the pesticides used in the catchment, the pyrethroids (lambda cyhalothrin, deltamethrin and cypermethrin) were found to be highly toxic under laboratory conditions to freshwater shrimp and Tilapia fingerling. Malformations, such as spinal deformities and abnormal yolk sac distribution, were observed in the fish embryos at pesticide concentrations below LC50 values. Currently there are no water quality guidelines available in the Philippines for pesticides. Such toxicity data on local species is highly beneficial in developing site-specific water quality guidelines. An acute hazard assessment was conducted for risk ranking of pesticides used in the Philippines by comparing the 48h LC50 values of selected pesticides to M. lar and actual concentrations of the pesticides detected in selected sampling areas within the Pagsanjan-Lumban catchment. The maximum measured concentration of profenofos (15.4μg/L) and pyrethroids (3–6μg/L) in the field samples collected in the Pagsanjan-Lumban catchment were above the 48h LC50 values. These compounds posed a high acute hazard (HQ>1) to freshwater shrimp in the Pagsanjan-Lumban catchment. Poor management practices in pesticide use could result in decline of rice-fish cultures and other economical invertebrates in some catchments in the Philippines.

Ecology and Biodiversity of Major Inland Bodies of Water: Challenges and Opportunities

Water is essential to life linking different ecosystems. Wetland or inland water bodies support the widest range of ecosystem services to humanity from being sources of potable drinking water, water for agricultural activities, and hydroelectric power to sites of aquaculture/fishery services. This paper focuses on the Philippines' three major wetlands: Laguna Lake, Lake Lanao and Agusan Marsh. Biodiversity and environmental integrity of these bodies of water are critically confronted by the different problems generated through the services they provide such as introduction of invasive species and rise of domestic, industrial and agricultural pollutants including potential impacts from climate change. Management still remains a challenge in these areas. Localized rehabilitation programs that have been put forward should be implemented urgently to stop and if possible reverse environmental degradation in these major inland bodies of water.

Effects of changing land use in the Pagsanjan–Lumban catchment on suspended sediment loads to Laguna de Bay, Philippines

Abstract Suspended sediment transport into Laguna Lake (Philippines) due to soil erosion from agricultural activities in the Pagsanjan–Lumban catchment is of great concern because of its impacts on water quality. The Pagsanjan–Lumban catchment contributes about 18–20% of the total freshwater inflows to the lake but represents only 10% of the catchment area. In this study the suspended sediment transport model, SedNet, was used to assess the relative impacts of changes in land use within the catchment on the quantities of suspended sediment discharged to the lake. The SedNet model predicted the total suspended sediment supply from the Pagsanjan–Lumban catchment (280 km2) to be 231.2 kt/y of which almost 70% was predicted to come from Balanac River, 23% from Bombongan River and the remaining 7% from the catchment downstream of these two river systems. Overall, the suspended sediment supply was predicted to decrease by 8% for every 20% of intercropped coconut plantations converted to forest. A greater reduction in the total suspended sediment yield discharging to the lake was predicted when reforestation was targeted at the steep slopes (

Public Perception of Local Communities towards the Sustainable Management of Laguna Lake, Philippines

Common failures in resolving multiple use conflicts are attributed to the inability of institutions to recognize and incorporate people's perceptions towards the resource. This study aims to determine the local communities' perceptions and factors influencing their perceptions towards Laguna Lake and its sustainable management. Copies of a self-administered questionnaire were distributed to systematically selected householders situated near and far from the Laguna Lake, Philippines. Correlation analysis determined the factors influencing the householder's perception. Results showed that attitudes, income and willingness to manage the lake affect the local communities' perception (P < 0.10). Results also showed that most respondents recognized that the lake is deteriorating due to pollution and each individual can take a role to sustainably manage it.

DNA damage induced by genotoxicants in zebrafish ( Danio rerio) embryos after contact exposure to freeze-dried sediment and sediment extracts from Laguna Lake (The Philippines) as measured by the comet assay

Laguna Lake, Philippines, is utilised as a resource for drinking and irrigation water and a major source of animal protein for more than 11 million residents. However, it also serves as a huge sink for anthropogenic pollutants from a variety of direct or indirect discharges. Given their well-known properties to accumulate organic pollutants, Lake Laguna sediments have been investigated by use of a newly developed sediment-contact assay to determine the bioavailable fraction of the total genotoxic hazard potential. Freshly fertilized zebrafish eggs (2 h after fertilization) were allowed to develop while exposed to different concentrations of freeze-dried sediments (exposure to bioavailable compounds) as well as organic extracts (complete genotoxic hazard potential including bioaccumulation) prepared from sediments collected at five sites within the lake. Following a 96 h exposure, single-cell suspensions were prepared from macerated larvae and analyzed for DNA strand-breaks by use of the comet assay. Genotoxicity could be identified in both solid-phase exposure scenarios as well as after exposure to organic sediment extracts. Only the South Bay (SB) site did not show a significant genotoxic burden relative to controls in tests of both freeze-dried sediment and organic extracts. In contrast, the Northwest Bay site displayed pronounced genotoxicity to the zebrafish embryos in both exposure scenarios. Perylene and copper in the sediments could be identified as potential causes of the genotoxic response. To compare the results (maximum induction coefficients) of zebrafish embryos with an established comet protocol, rainbow trout liver cells (RTL-W1) were exposed to the same extracts. The findings correlated well (Spearman correlation r = 0.90), proving a good reliability of the results from zebrafish primary cells. In conclusion, the present study demonstrates that the bioavailable fraction of the genotoxic pollutants may pose a threat for both benthic organisms and human health via drinking-water and fish consumption.

Laguna de Bay: Institutional development and change for lake basin management

AbstractLaguna de Bay is a large, shallow lake located near Manila, Philippines. The lake is drained by the Pasig River, which flows to Manila Bay. It periodically reverses direction, bringing saline water into this predominately freshwater body. The lake has historically been of great importance to locals who depend on it for fish and related livelihoods. Recently, it also has been considered a source of potable water for the Manila region. The intense land use in the watershed has caused enhanced siltation, and the lake has also been plagued by overfishing, intense aquaculture and water pollution from industrial and domestic sources. This paper overviews these issues and examines the role of the Laguna Lake Development Authority in developing and conserving the lake basin's resources. Two programmes related to fisheries development and an environmental user‐fee programme to control water pollution are critiqued. Lessons learned from the nearly 40 years of experience managing this tropical lake also are presented.

Effect of urban emissions on the horizontal distribution of metal concentration in sediments in the vicinity of Asian large cities

Metal contents of sediments in Manila Bay - Laguna Lake watershed in the Philippines were measured and detailed horizontal distribution was obtained. The distribution of zinc and lead concentration in Manila Bay clearly shows the effect of anthropogenic contamination and it was explained by the diffusion of lead and zinc rich anthropogenic particles discharged from Pasig River. The sediments in Laguna Lake were mostly natural particulate matters from surrounding mountains and they contained 20 mgPb/kg and 100 mgZn/kg, while the sediment taken at the heavily polluted branches of the Pasig River contained as high as 88 mgPb/kg and 310 mgZn/kg. The lead and zinc concentrations in the sediments of Manila Bay - Laguna Lake watershed were compared with those in the mouth of the Tama River, Tokyo, where the faster deposition of coarser natural origin particles and slower deposition of lead and zinc rich anthropogenic particles determined the sediment concentration. The comparison was also made with Hanoi City, Vietnam. In spite of the difference in time when leaded gasoline was prohibited, the difference in the lead concentrations of roadside deposits and sediments was not obvious in the vicinity of these three target cities. This is probably due to dilution by a large amount of suspended solids conveyed by the Pasig River in the case of the Philippines. Storm water runoff containing roadside deposits and discharge of untreated wastewater were identified as factors increasing zinc and lead concentrations of sediments in receiving waters based on the measurements on roadside deposits and the estimation of the contribution of untreated wastewater.

Communication Strategy Analysis of a Community-Initiated Social Mobilisation Against a Road Dike Project in Taguig, Metro Manila, Philippines

This study analysed the communication strategies employed by a community in Metro Manila through the Taguig Coalition Against Dike (TACAD), a people’s organisation, in a social mobilisation (socmob) against the Laguna Lake Road Dike Project (LLRDP). The most commonly mentioned by the 131 resident-respondents, four key informants and focus group discussion participants were interpersonal strategies such as house-to-house visit, informal discussion and consultation as well as meetings. Those strategies were perceived to be effective in terms of increasing environmental awareness and confidence to negotiate, together with their ability to empower. The most notable accomplishment of the TACAD’s socmob was the three-month moratorium of the road dike’s construction. Nevertheless, the road dike project was not completely stopped due to some factors beyond the control of the community residents. Drawing from the lessons learnt from this research, there is a need to study the collective and participatory approaches used by those directly affected by a government-initiated infrastructure project from the planning until evaluation stage.

Assessing water quality in a tropical lake using biomarkers in zebrafish embryos: developmental toxicity and stress protein responses

In order to achieve a more substantial appraisal of lake water quality, the assessment must not be based only on chemical measurements and analyses of the water itself, but even more so on the impact of existing conditions on aquatic biota. This is possible with the use of biotests or biomarkers, e.g. investigations of the developmental parameters (96-h embryotoxicity evaluate) or of the induction of heat shock proteins (proteotoxicity evaluate). To evaluate the suitability of these tests for environmental screening, fertilized zebrafish eggs were exposed to water samples collected from five sites of varying levels of stress from Laguna Lake, Philippines. Reconstituted water was used as laboratory control while water samples from a highly polluted freshwater source was used as positive control. Developmental parameters were noted and described within 48 and 96 h of exposure. Dilution experiments of the positive control were also done to further assess and compare toxicity potentials of Laguna Lake waters with those originating from a polluted freshwater. After the 96-h exposure, the levels of stress proteins (hsp 70) were determined in embryos from all exposure groups. Results showed 100% mortality in embryos exposed to undiluted positive control (PC) within only 12 h. Increasing dilution levels, however, resulted in lower mortality and lower abnormality rates. No detectable developmental differences were noted among embryos exposed to either the laboratory control or Laguna Lake waters at the end of 96 h, regardless of the source. Very high survival rates and high hatching success rates were observed in embryos exposed to lake waters as well as laboratory control, and the data did not differ significantly among the groups. Likewise, no significant malformations were noted among all developing embryos throughout the exposure period. However, the levels of heat shock proteins in the two sites located closest to Manila, the Philippine capital (Northern West Bay and Central West Bay), showed a pronounced elevation relative to the control, indicating that these stress proteins protect the embryos from the detrimental effects of pollutants in the water. Based on the 96-h early life stage (ELS) test, the water quality of the lake is good for fishery propagation despite the current levels of pollutants in the water. This finding is in accordance with the Class C status (i.e. suitable for fish growth and propagation) as given to the lake by the local environmental agency. On the other hand, data on proteotoxicity showed that the fish are under stress, presumably deriving from pollutants. This calls for a continuous monitoring and improvement of the lake water. The present study indicates that the two biomarker methods are very easy to use, practical, rapid, and sensitive for assessing water quality in a tropical lake and recommends for their incorporation into the future monitoring program of Laguna Lake.

Assessing contamination levels of Laguna Lake sediments (Philippines) using a contact assay with zebrafish ( Danio rerio) embryos

The present study investigated the suitability of a sediment contact assay using zebrafish ( Danio rerio) embryos to evaluate the degree of lake sediment contamination. As endpoints, developmental parameters (mortality, abnormality, heart rate, and hatching rate) as well as stress protein responses (hsp 70 levels) in the developing embryos were recorded during a 96-h exposure. Fertilized zebrafish eggs were exposed to both the whole as well as organic extract concentrations prepared from collected sediments from 5 sites along Laguna Lake, Philippines. Compared to whole sediment exposure, more severe embryotoxic and teratogenic responses were elicited in embryos exposed to organic extracts. However, since whole sediment-exposed embryos also revealed significant developmental defects, this exposure phase served as the more realistic exposure scenario in our study. Weak to strong upregulation of hsp 70 levels was also registered among embryos exposed to both whole sediments and organic extracts. The observed embryotoxic and proteotoxic responses by zebrafish embryos to Laguna Lake sediment exposures were discussed in relation to the analyzed contaminants in the sediments (heavy metals, PAHs (perylene), solvent). Overall, the present study points out that the sediment contact assay with zebrafish embryos offers a practicable and highly sensitive bioassay for the general assessment of sediment toxicity.

Set-up of a decision support system to support sustainable development of the Laguna de Bay, Philippines

Over recent decades, population expansion, deforestation, land conversion, urbanisation, intense fisheries and industrialisation have produced massive changes in the Laguna de Bay catchment, Philippines. The resulting problems include rapid siltation of the lake, eutrophication, inputs of toxics, flooding problems and loss of biodiversity. Rational and systematic resolution of conflicting water use and water allocation interests is now urgently needed in order to ensure sustainable use of the water resources. With respect to the competing and conflicting pressures on the water resources, the Laguna Lake Development Authority (LLDA) needs to achieve comprehensive management and development of the area. In view of these problems and needs, the Government of the Netherlands was funding a two-year project entitled ‘Sustainable Development of the Laguna de Bay Environment’.A comprehensive tool has been developed to support decision-making at catchment level. This consists of an ArcView GIS-database linked to a state-of-the-art modelling suite, including hydrological and waste load models for the catchment area and a three-dimensional hydrodynamic and water quality model (Delft3D) linked to a habitat evaluation module for the lake. In addition, MS Office based tools to support a stakeholder analysis and financial and economic assessments have been developed. The project also focused on technical studies relating to dredging, drinking water supply and infrastructure works. These aimed to produce technically and economically feasible solutions to water quantity and quality problems. The paper also presents the findings of a study on the development of polder islands in the Laguna de Bay, addressing the water quantity and quality problems and focusing on the application of the decision support system.

Challenges and opportunities in watershed management for Laguna de Bay (Philippines)

AbstractLaguna de Bay is the largest lake in the Philippines and the second largest freshwater lake in South‐East Asia. The lake is shallow with a mean depth of only 2.8 m. Rice paddies, sugar cane fields, coconut plantations and other agricultural fields make up large portions of the catchment area, although there is also extensive urbanization and industrialization. As industry and population around the lake have grown, the lake and its tributaries have become overwhelmed by industrial, commercial, agricultural and domestic pollution resulting in massive fish kills and polluted water. Laguna de Bay is under the management and protection of a national government agency known as Laguna Lake Development Authority (LLDA). In 1983, the LLDA was given the power to control and abate pollution within the Laguna de Bay watershed. The mandate of the LLDA includes the environmental regeneration and sustainable development and use of the lake’s waters, fisheries and wetlands. The LLDA receives no federal funds but it retains and uses collected fees from regulated industries. The LLDA has instituted an environmental‐user fee or pollution‐charge system that has given corporations an incentive to construct and use wastewater treatment plants at a lower cost than the required fees for dumping waste into Laguna de Bay. User fees provide more flexibility about how and when a user or industrial facility cleans up its manufacturing process. Many medium‐ and large‐sized domestic and multinational corporations have achieved at least 30–50% reductions in pollution loads. The user fees also encourage industry water conservation. Other creative approaches to conserving Laguna de Bay include ‘Environmental Armies’ that consist of volunteers who clean up river banks, demolish illegal fish pens and install low‐cost garbage traps at the river’s mouth. ‘Poison Awards’ are given annually and publicly to companies that continue to dump large amounts of waste into lake tributaries. Organizers also name a ‘Most Improved Company’ to provide a positive incentive. Laguna de Bay stakeholders face a severe shortage of resources to continue their work. Innovative strategies are needed to achieve pollution reductions from smaller industries

Survival and growth of bighead carp fry exposed to low salinities

Bighead carp (Aristichthys nobilis Oshima) fry of various ages (11, 18, and 35 days post-hatch) were exposed to the low salinities encountered during the annual intrusion of seawater in Laguna Lake, Philippines. Practical indices of salinity tolerance assessed the effect of a 96 h direct exposure to low salinities (0–16‰). Mean (MST) and median survival times (MST50) of fry decreased as salinity of rearing medium increased. Younger fry were less able to tolerate exposure to these salinities than their older cohorts. Median lethal salinity after 96 h (MLS) revealed higher tolerance among 35–day old fry (7.6‰) than 11 (2.3‰) and 18–day old fry (6.0‰), demonstrating that survival in saline water depends on their age at initial exposure to low salinities. Mean body weight of 18–day old fry reared in 0 and 2‰ for 3 and 4 weeks was higher than for those reared in 4 and 6‰ for the same period. Growth over these periods was inversely related with the range of salinities tested. These results demonstrate that, despite their known stenohalinity, bighead carp fry possess some degree of osmoregulatory capability, allowing them to survive and grow in lakes subjected periodically to saltwater inflow.

Agroecosystem analysis of Laguna Lake in the Philippines

Agroecosystem analysis of Laguna Lake in the Philippines

Results of exploratory coring in Laguna Lake, Philippines

Laguna Lake is a large lake in the central Philippines, close to Metro Manila. Agricultural, industrial and urban development is expanding rapidly in the Laguna Lake basin, giving rise to many forms of environmental stress in the lake and surrounding watershed. In particular, the lake appears to be subject to high rates of sedimentation, and the yields of both open lake and captive fisheries have severely declined. Exploratory coring was undertaken to provide a better understanding of lake sedimentation and long term trends in lake productivity. Actual rates of sedimentation are thought to be about 1–1.5 cm y−1 and are likely about half the calculated rate (unadjusted for sediment mixing). Trends in diatom content and surrogate data (including loss on ignition) suggest major variations which may correlate with changes in productivity and food-web structures.

Results of exploratory coring in Laguna Lake, Philippines

Results of exploratory coring in Laguna Lake, Philippines

Trace metal levels and speciation in sediments of some Philippine natural waters

This paper uses the limited number of studies available to date to compare the trace metal content of sediments of some important natural waters in Luzon Island (Philippines), which include: Laguna Lake and five of its tributary rivers, streams of a proposed model city (Lungsod Silangan), Agno River used to irrigate extensive rice farms, Manila Bay (the country's principal domestic and international port), and Bolinao Bay, which abounds in coral reefs. The average total Fe, Mn, Cu, Zn, Pb, Hg, and Cd content suggest, in general, relatively low to moderate pollution. The major association of the metals in the sediments were: Cu with organic matter, Zn with organics and reducible Fe/Mn oxides, and Fe and Mn with reducible Fe/Mn oxides. The order of chemical extractability of the metals from the sediment matrix was Mn > Cu > Zn > Fe for lake sediments, Mn > Zn > Cu > Fe for river sediments, and Mn > Cu = Zn > Fe for bay sediments.