Rhodora V. Azanza

University of the Philippines System | UPD · Marine Science Institute

One of the primary resources that Filipinos depend on for food and livelihood is marine biodiversity. On the other hand, with the advent of climate change, there have been unprecedented environmental shifts, characterized by sea level rise and increasing ocean temperatures. In this regard, this chapter will delve into the potential ramifications of...

This paper provides a review of toxic algal blooms in the Philippine and Malaysian coastal and marine systems, considering relevant available knowledge, including climate change dimension/s in the assessment of their recorded recent expansion. The first record of human toxicity in the Philippines associated with HABs/toxic algal blooms specifically...

This is the first report on hydrodynamic models to determine current and water residence time patterns for Matarinao and Murcielagos bays in the Philippines, which have a long history of harmful algal blooms (HABs). Field surveys were conducted in Matarinao Bay in April and August 2010 and in Murcielagos Bay in February 2011. Hydrodynamic models of...

This year’s 43rd Annual Scientific Meeting focuses on the theme “COVID-19 Pandemic: Learning from the Past, Coping with the Present, and Moving to the Next.” It has been more than a year that the whole nation, including the rest of the world, has been coping with the tremendous impacts of COVID-19 pandemic. While it is true that this pandemic has r...

Surveillance and characterization of emerging marine toxins and toxigenic dinoflagellates are warranted to evaluate their associated health risks. Here, we report the occurrence of the ciguatera poisoning-causative dinoflagellate Gambierdiscus balechii in the Philippines. Toxin production and chemical diversity of secondary metabolites in G. balechii...

This datasheet on Eucheuma covers Identity, Overview, Associated Diseases, Pests or Pathogens, Distribution, Dispersal, Biology & Ecology, Environmental Requirements, Natural Enemies, Impacts, Uses, Management, Genetics and Breeding, Economics, Further Information.

This datasheet on Kappaphycus covers Identity, Overview, Associated Diseases, Pests or Pathogens, Distribution, Dispersal, Biology & Ecology, Environmental Requirements, Natural Enemies, Impacts, Uses, Management, Genetics and Breeding, Economics, Further Information.

The Philippine Archipelago is surrounded by the West Pacific Ocean region on its eastern seaboard and the West Philippine Sea on the west. It is the apex of a coral-rich area known as the Coral Triangle, the center of marine biodiversity. The Filipino people have a long history of affinity to the sea that has been used as a source of food and means...

Proteins, lipids, and carbohydrates from the harmful algal bloom (HAB)-causing organism Pyrodinium bahamense were characterized to obtain insights into the biochemical processes in this environmentally relevant dinoflagellate. Shotgun proteomics using label-free quantitation followed by proteome mapping using the P. bahamense transcriptome and tran...

Alexandrium tamutum M.Montressor, A.Beran & U.John is a non-toxic, bloom-forming dinoflagellate species commonly reported in temperate waters. In this study, 8 cultures of A. tamutum established from Bolinao Channel and Manila Bay, Philippines were characterized in terms of their morphology, phylogeny and toxicity. Cells were roundish, measuring 25...

Unambiguous identification of unarmored dinoflagellates is important in distinguishing toxic from non-toxic species occurring in the coastal waters of the Philippines. In this study, molecular phylogeny inferred from rDNA sequences of Gymnodinium catenatum, Gymnodinium impudicum, and Akashiwo sanguinea-collected from Masinloc Bay, Zambales, Central...

Commercial, municipal, and aquaculture fisheries, and the marine ecosystem as a whole, are expected to experience climate change impacts in the coming decades. This is alarming, as marine resources contribute a significant portion (19-36%) to the food supply of the Philippines. Projections reveal that the Philippines shall experience increases in s...

Alexandrium minutum and Alexandrium tamutum are two closely related harmful algal bloom (HAB)-causing species with different toxicity. Using isobaric tags for relative and absolute quantitation (iTRAQ)-based quantitative proteomics and two-dimensional differential gel electrophoresis (2D-DIGE), a comprehensive characterization of the proteomes of A...

Epiphytic microalgae can significantly affect the host seaweed either by complementing, or competing for, resources. Here, epiphytic diatom and dinoflagellate species assemblages on the macroalgae Acanthophora spicifera, Hypnea pannosa and Gracilaria salicornia collected during the north-east (February), inter- (April) and south-west (June) monsoon...

In the Southeast Asian region, the Philippines and Malaysia are two of the most affected by Harmful Algal Blooms (HABs). Using long-term observations of HAB events, we determined if these are increasing in frequency and duration, and expanding across space in each country. Blooms of Paralytic Shellfish Toxin (PST)-producing species in the Philippin...

Sorption mechanics of the paralytic shellfish toxins (PSTs), saxitoxin (STX) and neo-saxitoxin (neo-STX), on algal polysaccharide gels was characterized using surface chemistry models. Refined (RC), semi-refined (SRC) carrageenan and alginate showed sorption of STX and neo-STX. The sorption of PSTs on RC, SRC and alginate was affected by contact ti...

Associated and algicidal bacteria play roles in the succession and decline of phytoplankton blooms, including those of harmful algal bloom (HAB)-forming species. Limited studies on HAB-associated bacterial ecology have resulted in our incomplete understanding of HABs dynamics. Diverse phytoplankton-bacterial interactions have also led to studies on...

Bivalve molluscs represent an important food source within the Philippines, but the health of seafood consumers is compromised through the accumulation of harmful algal toxins in edible shellfish tissues. In order to assess the dynamics of toxin risk in shellfish, this study investigated the uptake, depuration, assimilation, and analogue changes of...

The viability of ballast water phytoplankton was assessed through incubation experiment. Leptocylindrus sp. and Thalassionema spp. Were found to be viable when incubated in port water and ballast water media showing some increase in cell numbers. Bloom-forming diatom taxa, such as Chaetoceros spp. and Coscinodiscus spp., potentially harmful diatom...

Morphology and phylogeny of the marine woloszynskioid dinoflagellate Biecheleriopsis adriatica, collected from Philippines, Singapore, Palau and Japan, were examined by using light and scanning electron microscopy (SEM), and molecular phylogeny based on rDNA sequences. Cells of these cultures were ovoid to spherical, measured 11.5–17.3 μm in length...

Morphology and phylogenetic position of the marine harmful raphidophyte Chattonella isolated from Bolinao, Pangasinan, Philippines in 2013 and 2017 were examined using light microscopy and molecular phylogeny inferred from LSU rDNA and ITS sequences. Cells of Chattonella were variable in shape and typically teardrop- shaped with a roundish antapica...

Morphology and phylogenetic position of the marine harmful raphidophyte Chattonella isolated from Bolinao, Pangasinan, Philippines in 2013 and 2017 were examined using light microscopy and molecular phylogeny inferred from LSU rDNA and ITS sequences. Cells of Chattonella were variable in shape and typically teardrop- shaped with a roundish antapica...

Studying ocean microbiomes is important in understanding the effects of the changing environment on our seas. The Philippines, being an archipelago, has been regarded as one of the most vulnerable regions under climate change scenarios, and understanding of the functions and diversity of microbial communities is a paramount step toward mitigating a...

In line with the ASEAN-India project “Extent of Transfer of Alien Invasive Organisms in South/Southeast Asia via Shipping”, phytoplankton and bacterial communities in the waters off South Harbour, Manila Bay were investigated. Sampling was done in July and August 2012 and in April and May 2013. A total of 67 phytoplankton species including 29 diato...

Limited knowledge of native marine biodiversity hinders effective biodiversity management to safeguard South and Southeast Asia’s marine coastal environment against the threat of invasive species transfer through shipping. In particular, sessile marine biofouling organisms in South East Asian ports are poorly known. Through the support of the ASEAN...

Rapid and species-specific detection, and quantification of pathogenic bacteria are fundamental for monitoring and assessment of the risk they pose to any ecosystem. The study employed Vibrio cholerae, a human pathogen responsible for the life-threatening diarrhoeal disease, cholera and one among the most unwanted from marine bioinvasion point of v...

In line with the ASEAN-India project “Extent of Transfer of Alien Invasive Organisms in South/Southeast Asia via Shipping”, phytoplankton and bacterial communities in the waters off South Harbour, Manila Bay were investigated. Sampling was done in July and August 2012 and in April and May 2013. A total of 67 phytoplankton species including 29 diato...

An immersion experiment was conducted in the Manila South Harbor to document the development of sessile biofouling communities. Test panels were submerged below the sea surface in April 2012 for short- (one and three months) and long-term (one year) exposures in seawater, then foauling types and occurrences were scored based on digital images of pa...

In contrast to temperate Harmful Algal Blooms (HABs), knowledge on the mechanisms driving tropical HABs are less well studied. The interaction of a seasonal temperature window, cysts (for certain species) and large-scale transport are some of the key processes in temperate HABs. In the Philippines, HABs occur not along long open coastlines, but in...

Life cycle-based adaptations are integral to the ecology of most organisms. For the toxic microalgal species Pyrodinium bahamense, Alexandrium fundyense, Pseudo-nitzschia spp., and Nodularia spumigena, the properties and behaviours of their life cycle stages enable them to thrive in diverse marine environments. Planktonic blooms of these species ar...

Harmful algal blooms (HABs), contributing to both fisheries effects due to high-biomass algal blooms and shellfish or fish poisoning due to toxic algae, have long been reported in coastal waters of the Asian region, especially in East and Southeast Asia. HAB-related issues have continuously been of both social and economic concern. Although there h...

Isolates of Alexandrium species collected in the Philippine waters were examined during the exponential growth phase to compare their toxicities and protein expression profiles, and also to correlate protein expression with toxin production. Molecular methods showed that Alexandrium cf. pacificum was genetically divergent from Alexandrium tamarense...

The impetus to enhance the quality and quantity of industrial-scale supplies of raw material and extract production drives the needs for research and monitoring of the reproductive biology and physiology of commercial species/strains/variants of Kappaphycus and Eucheuma. Publications and advancements in these fields are reviewed in this chapter. Th...

Pyrodinium bahamense var. compressum (Pbc) is a major public health concern particularly in the Southeast Asian region, and increasing threat brought by heavy metal pollution has greatly disturbed and altered the ecological balance of the region's marine waters. Herein, we report the effect of cadmium, a biotoxic metal, to cell cultures of Pbc. Wit...

The ocean-based " blue economy " is a significant part of the Philippine economy that has largely been taken for granted despite its enormous potential. It is of critical importance to a substantial segment of our population dependent on the seas and coastal resources for their livelihood and sustenance, appreciably enlarge the country's wealth, an...

Removal of Paralytic Shellfish Toxin (PST) from the water column using ball clay

Marine centric diatom was isolated from a mariculture site as a potential microalgae species for biodiesel production. Unialgal culture was developed for identification, growth curve determination and lipid quantification. Morphological characteristics suggested the similarities to Coscinodiscus centralis. Doubling time was 3.18 ± 0.50 days. The cr...

Mitigation of Harmful Algal Blooms (HABs) through clay flocculation has been widely explored, yet the algal removal and cellular effects was not fully understood. Here we examined the effect of different pH levels and varying ionic strength on the removal efficiency (RE) of ball clay on toxic dinoflagellates: Pyrodinium bahamense var. compressum, G...

Pyrodinium Blooms are recurrent, expensive and a fatal problem plaguing the Philippines. Pyrodinium bahamense var. compressum, considered as the main causative organism of Paralytic Shellfish Poisoning (PSP) in the Philippines, have been recorded in more than 31 coastal areas and embayments since 1983. These blooms have widely affected the Philippi...

Many aspects of the biology and ecology of the toxic dinoflagellate Pyrodinium bahamense var. compressum are still poorly understood. In this brief note, we present identification of its associated intracellular bacteria or endosymbionts via PCR cloning and 16s rRNA gene sequencing and their localization by confocal microscopy, a first for Pyrodini...

Marine biomasses used in biogasification system are usually treated as terrestrial feedstock after salt removal. However, biogas production of sea wrack biomass run under thalassic (marine) conditions, and seeded with different inocula [cow manure (CM), marine sediment (MS) and sea wrack-associated (SWA) microflora] showed the potential for cheaper...

Malampaya Sound is an enclosed bay in Palawan, Philippines. A salinity maximum or salt plug was discovered in the middle of the Sound by a field survey in May 2005 and successfully simulated using a Delft3D numerical model of the sound, forced with tide and freshwater discharge at the lateral boundaries, and evaporation at the surface. Different co...

Mutual flocculation of algal cells and clay particles after clay addition is one of the promising remedial measures to counter the negative impacts of harmful algal blooms (HABs). However, very few studies to explain the mechanisms, factors and effects of clay particles on algal physiology and morphology have been done. This gap in knowledge is the...

Pellicle or temporary cysts of Pyrodinium bahamense var. compressum (Böhm) Steidinger, Tester & F.J.R. Taylor and their role in bloom dynamics have not yet been adequately characterized and understood. We investigated the role of temperature- and nutrient-mediated stress as factors that could induce pellicle formation in batch cultures. Cellular fe...

In recent decades, eutrophication has been identified as a major problem in coastal and estuarine systems. Eutrophication can be due to cultural activities but can also be due to natural factors. This study explores the possible role of geomorphic change in the eutrophication history of Juag Lagoon, which is one of the sites with harmful algal bloo...

The Japanese eel Anguilla japonica spawns in the North Equatorial Current in the Philippine Sea and their larvae are transported to their freshwater growth habitats in East Asia. Here we report the occurrence and biological characteristics of glass eels of A. japonica that were collected on northern Luzon Island of the Philippines, the southern lim...

Bacteria from seaweeds as epibionts have been reported to have major role/s in algal physiology and survival by secreting compounds with bioactivity like inhibitory/other potential harmful/pathogenic effects. Some of these epibionts have been reported to cause mortality against certain species of noxious phytoplankton, i.e. fish-killing and toxic s...

We utilized biodiversity indices and multivariate techniques to investigate the relationship between environmental conditions and net phytoplankton composition and abundance during early (November) and mid (February) northeast (NE) monsoon, intermonsoon (May), and southwest (SW) monsoon (August) in Panguil Bay, an exploited mangrove estuary in Nort...

Anguilla luzonensis and A. huangi were each described in 2009 using eels obtained from northern Luzon Island. We examined the taxonomic status of these two groups of eels using morphological and molecular genetic characters. There were no significant differences in two vertebrae counts between eels of A. luzonensis and A. huangi. Mitochondrial 16S...

Sea wrack (dislodged sea grasses and seaweeds) was used in biogas production. Fresh water scarcity in island communities where sea wrack could accumulate led to seawater utilization as liquid substrate. Three microbial seeds cow manure (CM), marine sediment (MS), and sea wrack-associated microflora (SWA) were explored for biogas production. The ave...

A mitigation strategy for harmful algal blooms (HABs) is to remove cells from the water column be physically trapping then through flocculation with clay particles and subsequently settling algal cells to the bottom. of prime consideration is the effect of clay addition on the non-target benthic and water column organisms. This study examined the e...

Since the first reported Paralytic Shellfish Poisoning case in Bolinao, Pangasinan in 2002, monitoring efforts has been directed toward the determination of the presence Alexandrium spp. in the area. Data on the elaboration of the identity of causative organism and seasonality including spatial distribution have been fragmented and lacking despite...

To study the complex patterns governing Harmful Algal Blooms (HAB), an individual- or agent-based modeling approach was employed. The constructed model was able to mechanistically represent both the biological and the physico-chemical factors involved during events of bloom and decline of the toxic dinoflagellate, Pyrodinium bahamense var. compress...

Coastal water quality conditions in the months prior to and during the 2010 fish kill of farmed milkfish (Chanos chanos) in Bolinao and Anda, Pangasinan were determined to have high total dissolved inorganic nitrogen (0.31 - 24.2 mu M) and dissolved phosphate (0.09 - 4.47 mu M) along the Guiguiwanen and Caquiputan channels. Low N:P ratios (0.18 - 1...

Ciguatera fish poisoning (CFP) is an illness caused by eating fish contaminated with toxins called ciguatoxins (CTX) produced by dinoflagellates, particularly the Gambierdiscus species. People affected by CFP suffer from gastrointestinal and cardiac symptoms, and in some cases, chronic neurologic symptoms. In the Philippines, diagnosis of CFP in hu...

The first record of bacteria with algicidal activity against Alexandrium sp. strain AMBRVA031710, a Harmful Algal Bloom (HAB)-causing dinoflagellate was isolated from Bolinao, Pangasinan. Water samples for bacterial isolation were collected from 14 selected stations in Bolinao during the Northeast (NE) Monsoon, Tradewind (TW) and Southwest (SW) Mon...

Harmful algal blooms are a recurrent, expensive and at times fatal problem plaguing the Philippines. In particular, Sorsogon Bay in the Bicol region has experienced prolonged shellfish bans due to blooms by the Paralytic Shellfish Poisoning causative species Pyrodinium bahamense var. compressum (Pbc). In order to help explore and understand the pop...

Dinoflagellate genomes are extremely large (3-300Gb) and many aspects of its content and complexity are unknown. It has also been shown that dinoflagellates harbor intra- and extracellular bacteria, whose roles are similarly unexplored. This confounds gene content and functional analysis, particularly in understanding the roles dinoflagellates and...

Pyrodinium bahamense var. compressum is a toxic dinoflagellate that produces paralytic shellfish poisoning toxins. It is responsible for the chronic toxicity of shellfish in many coastal areas of the Philippines and other South East Asian countries. For the purpose of using antibiotic treatment to possibly generate axenic cultures and understand t...

We report the first occurrence of harmful algal bloom (HAB) caused by a non-toxic dinoflagellate, Cochlodinium sp. in Philippine waters, particularly, in Kalangahan Pt.-Manticao Pt., Iligan Bay on March 13-18, 2002. Two patches of Cochlodinium sp. bloom, associated with fish kills in Kalangahan Pt.-Mantacao Pt., Iligan Bay, caused localized water d...

This paper constitutes the first cyst record of a eutrophic tropical mariculture area with harmful algal blooms since 2002 and provides contribution to the global record on dinoflagellate cysts, specifically from Northern part of Southeast Asia. Surface sediment samples from 54 stations in October 2006 and 5 stations from 2004 to 2006 Bolinao, Pang...

Harmful algal bloom occurrences worldwide have prompted the testing and use of methods to control and mitigate their detrimental effects. This study investigates the potential of Philippine clay minerals to physically remove phytoplankton cells under laboratory conditions. Ball clay had the highest removal efficiency (∼95%) for Pyrodinium bahamense...

For the first time the potential of Noctiluca scintillans, a non-toxic mixotrophic dinoflagellate, in bioconverting and/or excreting saxitoxin has been illustrated, thus contributing to the limited knowledge on the aspects of toxin pathways in the food chain/web and predator-prey preferences. Noctiluca growth rate increased with higher Pyrodinium c...

We examined general characteristics and genetic divergences of whole mitochondrial genome sequences for all 19 species/subspecies of the genus Anguilla including a recently described new species, A. luzonensis. The entire genome ranged from 16,550 (A. borneensis) to 16,833 base pairs (A. nebulosa labiata), and general characteristics such as length...

Harmful algal blooms (HABs) occur frequently in the South China Sea (SCS), causing enormous economic losses in aquaculture. This paper analyzed historical HAB records during the period from 1980 to 2003 in SCS. The data show that HABs-affected areas have expanded and the frequency of HABs varied during this period. The seasonal and annual variation...

The coastal waters of Bolinao, Pangasinan, Philippines experienced environmental changes over a 10-year period (1995-2005), the most significant effect of which was the major fish kill event in 2002 that coincided with the first reported Philippine bloom of a dinoflagellate Prorocentrum minimum. Days before the bloom, dissolved oxygen was < 2.0 mg/...

The supply of nitrogen and phosphorus in coastal zones through time is reflected in the nutrients’ concentration in the sediment record. Five aquaculture sites in the Philippines were investigated in an effort to establish how long-term changes in land and coastal water use could have led to biogeochemical modifications affecting the coastal ecosys...

The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or posit...

Temporal variation in the type and abundance of dinoflagellate cysts in Manila Bay, Philippines, is established using 210Pb-dated sediment cores. At least 17 dinoflagellate cyst species, including those of the toxic species, Pyrodinium bahamense var. compressum, were identified. P. bahamense may have been present in the area since at least the 1920...