Journal Articles - UP - MSI

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17-year change in species composition of mixed seagrass beds around Santiago Island, Bolinao, the northwestern Philippines
Tanaka, Yoshiyuki; Go, Gay Amabelle; Watanabe, Atsushi; Miyajima, Toshihiro; Nakaoka, Masahiro; Uy, Wilfredo H.; Nadaoka, Kazuo; Watanabe, Shuichi; Fortes, Miguel D. (Elsevier, 2014)
Effects of fish culture can alter the adjacent ecosystems. This study compared seagrass species compositions in 2012 with those in 1995, when fish culture was less intensive compared to 2012 in the region. Observations were conducted at the same four sites around Santiago Island, Bolinao: (1) Silaqui Island, (2) Binaballian Loob, (3) Pislatan and (4) Santa Barbara, and by using the same methods as those of Bach et al. (1998). These sites were originally selected along a siltation gradient, ranging from Site 1, the most pristine, to Site 4, a heavily silted site. By 2012, fish culture had expanded around Sites 2, 3 and 4, where chlorophyll a (Chl a) was greater in 2012 than in 1995 by one order of magnitude. Enhalus acoroides and Cymodocea serrulata, which were recorded in 1995, were no longer present at Site 4, where both siltation and nutrient load are heavy.
A benefit-cost comparison of varying scales and methods of coral reef restoration in the Philippines
Abrina, Tara Alessandra S.; Bennett, Jeff (Elsevier, 2021-12)
The slow rate of recovery in some reefs around the Philippines has prompted the widespread investment in active reef restoration in the country. However, from the point of view of society, these different coral reef restoration investments have not yet been fully compared in a benefit-cost analysis. In this paper, the economic efficiencies of four coral reef investments are compared – at two different scales (local and national) and two different technologies (‘coral gardening’ and ‘mass larval enhancement’). The values are derived from a previous valuation study that used the Choice Modelling method of estimating non-market values of coral reef restoration. The capacity of these values to facilitate comparisons among reef investments is thus assessed in this paper. Based on predictions from reef restoration scientists the Philippines, the mass larval enhancement investments are estimated to produce higher net benefits and benefit-cost ratios compared to those of coral gardening. In terms of scale, higher net social outcomes for the local-scale investments support more localized approaches to coral restoration.
A comparison of two benthic survey methods
Mingoa, S. S. M.; Menez, L. A. B. (Springer, 1988)
The belt transect and the flowmeter methods, used to survey sedentary benthic organisms, were compared based on abundance estimates of tridacnid clams in the Cagayan Islands, Philippines, in April 1985. Two-way ANOVA and chi-square tests (P<0.05) show that both methods recorded similar estimates for the number of clams (regardless of species), both methods gave similar estimates for the number of individuals per species, and one or both methods may be biased for certain sizes of clams. Individuals smaller than 6 cm shell length seemed to be underestimated by the flowmeter method. Future studies must investigate the size selectivity of the method used, for instance by conducting permanent belt, transect surveys of varied belt widths (e.g. 1, 1.5,2,2.5 m) and then comparing the recorded lengths of the most abundant clams. This will aid investigators to evaluate their data properly, and enable comparison of clam-stock estimates between surveys.
A conserved biosynthetic gene cluster is regulated by quorum sensing in a shipworm symbiont
Robes, Jose Miguel D.; Altamia, Marvin A.; Murdock, Ethan G.; Concepcion, Gisela; Haygood, Margo G.; Puri, Aaron W. (American Society for Microbiology, 2022-06-14)
Bacterial symbionts often provide critical functions for their hosts. For example, wood-boring bivalves called shipworms rely on cellulolytic endosymbionts for wood digestion. However, how the relationship between shipworms and their bacterial symbionts is formed and maintained remains unknown. Quorum sensing (QS) often plays an important role in regulating symbiotic relationships. We identified and characterized a QS system found in Teredinibacter sp. strain 2052S, a gill isolate of the wood-boring shipworm Bactronophorus cf. thoracites. We determined that 2052S produces the signal N-decanoyl-l-homoserine lactone (C₁₀-HSL) and that this signal controls the activation of a biosynthetic gene cluster colocated in the symbiont genome that is conserved among all symbiotic Teredinibacter isolates. We subsequently identified extracellular metabolites associated with the QS regulon, including ones linked to the conserved biosynthetic gene cluster, using mass spectrometry-based molecular networking. Our results demonstrate that QS plays an important role in regulating secondary metabolism in this shipworm symbiont. This information provides a step toward deciphering the molecular details of the relationship between these symbionts and their hosts. Furthermore, because shipworm symbionts harbor vast yet underexplored biosynthetic potential, understanding how their secondary metabolism is regulated may aid future drug discovery efforts using these organisms.
A multi-framework analysis of stakeholders’ perceptions in developing a localized blue carbon ecosystems strategy in Eastern Samar, Philippines
Quevedo, Jay Mar D.; Ferrera, Charissa M.; Faylona, Marie Grace Pamela G.; Kohsaka, Ryo (Springer Science and Business Media LLC, 2024-01-25)
Blue carbon ecosystems (BCEs) are vital for global climate change mitigation and offer diverse local ecosystem co-benefits. Despite existing literatures on integrating national and international BCE agendas at the local level, the development and implementation of localized BCE strategies often lag behind. To provide insights on this knowledge gap, we present a case study conducted in Eastern Samar, Philippines. Employing a multi-framework analysis- encompassing DPSIR (drivers, pressures, state, impact, responses), SOAR (strengths, opportunities, aspirations, results), and PESTLE (political, economic, social, technological, legal, environmental) frameworks, stakeholder perceptions collected from focus group discussions highlight issues and challenges in developing and implementing a BCE strategy. Findings reveal that the aftermath of Typhoon Haiyan in 2013 in the study sites stimulated conservation efforts and raised awareness, but governance structures and policy enforcement influence the success and longevity of management and conservation efforts. Through the integration of multiple frameworks, this study outlined a potential localized BCE strategy, emphasizing both internal priorities such as stakeholder engagement and alternative livelihoods and external priorities related to policy and technological supports. While developed based on a specific case study in the Philippines, the proposed strategy is presented in a general manner, enabling its potential replication in other provinces in the Philippines or in countries with similar geographic settings.
A review of the status of Philippine reefs
Gomez, E. D.; Aliño, P. M.; Yap, H. T.; Licuanan, W. Y. (Elsevier BV, 1994-01)
Since 1979, the status of Philippine reefs has been periodically updated. While conditions of the reefs during the early surveys were assessed in terms of live coral cover per se, the ‘coral mortality index’ was applied to the sets of data collected during the past 7 yr which may be a better gauge in determining the health of the reefs. Generally, most reefs surveyed are in fair condition. Major destructive factors described are sedimentation and siltation from coastal development and activities inland, illegal and destructive methods of fishing, and overfishing. If the reefs are to continue to provide for the present and future users, the ecological processes that render them productive must be maintained through integrated approaches of coastal area management.
A unique reproductive strategy in the mushroom coral Fungia fungites
Eyal-Shaham, Lee; Eyal, Gal; Ben-Zvi, Or; Sakai, Kazuhiko; Harii, Saki; Sinniger, Frederic; Hirose, Mamiko; Cabaitan, Patrick; Bronstein, Omri; Feldman, Bar; Shlesinger, Tom; Levy, Oren; Loya, Yossi (Springer Science and Business Media LLC, 2020-09-30)
The vast majority of scleractinian corals are either simultaneous hermaphrodites or gonochoric. Exceptions to these are rare. Nevertheless, species belonging to the family Fungiidae are known to exhibit a wide variety of reproductive strategies. We examined the reproductive ecology of the mushroom coral Fungia fungites in Okinawa. Our study was conducted as part of a long-term, wide-ranging project (2009–2010 and 2013–2017) which explored the unique reproductive strategies of several species belonging to the family Fungiidae. Here we report the co-occurrence of males, females, and hermaphrodite individuals in a long-term monitored population of the reproductively atypical brooder coral F. fungites within the family Fungiidae. F. fungites status as a single-polyped solitary coral, was used to perform manipulative experiments to determine the degree of dependence of an individual coral on its conspecific neighbors for reproduction, and examined whether a constant sperm supply is obligatory for the continuous production of planulae. Isolated females of F. fungites exhibited a distinctive reproductive strategy, expressed in continuously releasing planulae also in the absence of males. Observations conducted on a daily basis for 2.5 months (throughout the reproductive season of 2015) revealed that some of these individuals released planulae continuously, often between tens and hundreds every day. In an effort to explain this phenomenon, three hypotheses are discussed: (1) Self-fertilization; (2) Asexual production of planulae (i.e., parthenogenetic larvae); and (3) Extended storage of sperm. Finally, we emphasize the importance of continuous and long-term monitoring of studies of coral reproduction; through further genetic studies of coral populations representing a broad range of species and their larval origin.
Accumulation and exposure classifications of plastics in the different coastal habitats in the western Philippine archipelago
Gomez, Norchel Corcia F.; Cragg, Simon M.; Ghiglione, Jean-François; Onda, Deo Florence L. (Elsevier, 2023-11)
Studies consistently ranked the Philippines as one of the top contributors of plastic wastes leaking into the ocean. However, most of these were based on probabilities and estimates due to lack of comprehensive ground-truth data, resulting also in the limited understanding of the contributing factors and drivers of local pollution. This makes it challenging to develop science-driven and locally-contextualized policies and interventions to mitigate the problem. Here, 56 sites from different coastal habitats in the western Philippine archipelago were surveyed for macroplastics standing stock, representing geographic regions with varying demography and economic activities. Clustering of sites revealed three potential influencing factors to plastic accumulation: population density, wind and oceanic transport, and habitat type. Notably, the amount and types of dominant plastics per geographic region varied significantly. Single-use plastics (food packaging and sachets) were the most abundant in sites adjacent to densely populated and highly urbanized areas (Manila Bay and eastern Palawan), while fishing-related materials dominated in less populated and fishing-dominated communities (western Palawan and Bolinao), suggesting the local industries significantly contributing to the mismanaged plastics in the surveyed sites. Meanwhile, isolated areas such as islands were characterized by the abundance of buoyant materials (drinking bottles and hygiene product containers), emphasizing the role of oceanic transport and strong connectivity in the oceans. Exposure assessment also identified single-use and fishing-related plastics to be of “high exposure (Type 4)” due to their high abundance and high occurrence. These increase their chances of encountering and interacting with organisms and habitats, thus, resulting into more potential harm. This study is the first comprehensive work done in western Philippines, and results will help contextualize local pollution, facilitating more effective management and policymaking.
Acetic acid pretreatment in agar extraction of Philippine Gelidiella acerosa (Forsskaal) Feldmann et Hamel (Rhodophyta, Gelidiales)
Roleda, M. Y.; Montaño, N. E.; Ganzon-Fortes, E. T.; Villanueva, R. D. (Walter de Gruyter GmbH, 1997)
Application of different pre-extraction treatments and extraction methods were used to isolate agar from Gelidiella acerosa. Acetic acid pretreatment entailed soaking the sample in 0.5% acetic acid for 1 hour at 16-20 °C. Alkali pretreatment entailed treatment with l N NaOH at 90°C for 1 hour and eutralization in weak acid for another hour at 16-20 °C. Native agar was extracted directly from air dried samples. One hour extraction using steam pressure at 15-2PSI and boiling at 100 °C in a water bath were applied respectively. Comparative analysis showed that the acetic acid pretreated and autoclaved sample gave the highest agar yield (29.8 ± 2.41%) and gel strength (676 ± 4 g cm"2) among the extraction methods applied. Other physico-chemical properties of acid-modified agar were measured. Relative viscosity of a 1.0% solution at 65 °C ranged from 5-70 cps. A melting temperature of 90-98 °C is comparable to that of the agars from most Gelidiales, while a gelling temperature of 42-47 °C is relatively high which is suspected to be associated with a number of chemical variables masking or altering the basic structural unit of agar. Temperature hysteresis (difference between gelling and melting temperatures) at 48—50 °C was comparable to that of Difco Bacto agar tested at 50 °C.
Age, growth, and population structure of Conomurex luhunuas
Sanchez-Escalona, Katherine; Aliño, Porfirio (National Fisheries Research and Development Institute, 2022-12)
Age and growth dynamics of Conomurex luhuanus were investigated to determine the population structure. Age-specific change in shell shape determined with geometric morphometrics revealed discrimination of shape between 0-3 years old at 99–100% while 3–4 years old can be separated with 81% certainty. Using the age discrimination data, K and L∞ were estimated at 1.00 year and 7.28 cm, respectively. Recruitment is bimodal with natural mortality (M) of 0.71 and fishing mortality (F) approximated at 3.92 year. The exploitation rate (E) is 0.85 year, indicating probable overharvesting of the population under study. The presence of a deep-water population, age-specific burying behavior, and bimodal recruitment pattern are possible resilience factors.
The study was supported by a grant from PCAARRD-DOST.
Agelasine F from a Philippine Agelas sp. sponge exhibits in vitro antituberculosis activity
Mangalindan, Gina; Talaue, Meliza; Cruz, Lourdes; Franzblau, Scott; Adams, Linda; Richardson, Adam; Ireland, Chris; Concepcion, Gisela (Georg Thieme Verlag KG, 2000-12-31)
Marine sponge samples were collected in Baler, Aurora, Philippines, and extracts were tested for in vitro antituberculosis activity. An orange Agelas sp. sponge yielded the known compound, agelasine F, which inhibited some drug resistant strains of Mycobacterium tuberculosis in vitro at concentrations as low as 3.13 μg/ml. Activity against M. tuberculosis residing within macrophages required concentrations of 13 - 22 μg/ml which was below the IC50 for Vero cells (34 μg/ml).
Ammonium and phosphate excretion in three common echinoderms from Philippine coral reefs
Dy, Danilo T.; Yap, Helen T. (Elsevier BV, 2000-08)
The ammonium and phosphate excretion and oxygen consumption of three species of echinoderms (Tripneustes gratilla, Protoreaster nodosus and Ophiorachna incrassata) commonly encountered in Philippine coral reefs were investigated in relation to time of day (i.e. daytime between 10:00 and 12:00 h vs. nighttime between 22:00 and 24:00 h) and their recent feeding history (i.e. recently-collected vs. short-term starvation for 3±1 days). The experiment used whole organism incubations and followed a nested hierarchical design. Ammonium excretion rates were 1447±310 nmol g−1 DW h−1 (mean±S.E., n=24) for T. gratilla, 361±33 for O. incrassata and 492±38 for P. nodosus. Ammonium excretion differed significantly among species, time of incubation and recent feeding history. Interaction between species and recent feeding history was also significant. The organisms excreted more ammonium during daytime except for starved specimens of O. incrassata. In addition, animals that were starved in the laboratory for a few days had a tendency to excrete more ammonium than recently-collected specimens. Phosphate excretion rates were 25±13 nmol g−1 DW h−1 for T. gratilla, 10±2 for O. incrassata and 4±1 for P. nodosus. There were no significant differences in phosphate excretion among the three species of echinoderms, their recent feeding history and time of day. Oxygen consumption rates were 286±24 μg O2 g−1 DW h−1 for T. gratilla, 64±3 for O. incrassata and 54±3 for P. nodosus. Oxygen consumption differed significantly among species and recent feeding history but differed only slightly with time of incubation. There was a significant correlation between oxygen consumption and ammonium excretion (r=0.48, P=0.018), and between oxygen consumption and phosphate excretion (r=0.41, P=0.047) for T. gratilla. The nutrient excretion by tropical echinoderms is another pathway by which inorganic nutrients are regenerated in coral reef communities. However, the quantity of nutrients excreted is dependent on the species of echinoderms, their nutritional status and time of day.
An experimental test of the occurrence of competitive interactions among SE Asian seagrasses
Duarte, C. M.; Terrados, J.; Agawin, N.; Fortes, M. D. (Inter-Research Science Center, 2000)
The occurrence of competitive interactions among the seagrass species present in a multispecific SE Asian seagrass meadow was tested by the cumulative removal of shoots of an increasing number of seagrass species from the meadow in order of decreasing and increasing resource requirements for plant growth. The removal of shoots of the dominant species Thalassia hemprichii had very few effects on shoot size, shoot density and leaf area index of the extant seagrass species. The shoot density of Enhalus acoroides decreased when T. hemprichii shoots were removed, but that of Syringodium isoetifolium increased when the shoots of all the species with higher resource requirements than itself were removed from the experimental plots. The size of Halophila ovalis shoots decreased by 30% when both T. hemprichii and E. acoroides shoots were removed from the plots. The shoot density of T. hemprichii increased only when the shoots of all the accompanying species were removed from the plots. The results show that species interactions in this multispecific seagrass meadow are asymmetric. The elucidation of the nature of the interactions among seagrass species provides a key to understanding the maintenance of the high biodiversity and production that characterizes pristine SE Asian coastal ecosystems.
Anti-inflammatory activity of monosubstituted xestoquinone analogues from the marine sponge Neopetrosia compacta
Susana, Shalice R.; Salvador-Reyes, Lilibeth A. (MDPI, 2022-03-22)
Chronic inflammation is recognized as a contributor to multiple chronic diseases, such as cancer, cardiovascular, and autoimmune disorders. Here, a natural products-initiated discovery of anti-inflammatory agents from marine sponges was undertaken. From the screening of 231 crude extracts, a total of 30 extracts showed anti-inflammatory activity with no direct cytotoxic effects at 50 μg/mL on RAW 264.7 (ATCC®TIB-71™) murine macrophage cells stimulated with 1 μg/mL lipopolysaccharide (LPS). Bioactivity-guided purification of the anti-inflammatory extract from the sponge Neopetrosia compacta led to the isolation of xestoquinone (1), adociaquinone B (2), adociaquinone A (3), 14-hydroxymethylxestoquinone (4), 15-hydroxymethylxestoquinone (5), and an inseparable 2:1 mixture of 14-methoxyxestoquinone and 15-methoxyxestoquinone (6). Compounds 1–6 caused a concentration-dependent reduction of nitric oxide (NO) production in LPS-stimulated RAW 264.7 cells, with 4–6 having low micromolar IC50 and acceptable selectivity index. Gene expression analysis using qRT-PCR showed that 1, 5, and 6 downregulated Il1b and Nos2 expression by 2.1- to 14.8-fold relative to the solvent control at 10 μM. Xestoquinone (1) and monosubstituted analogues (4–6), but not the disubstituted adociaquinones (2 and 3), caused Nrf2 activation in a luciferase reporter MCF7 stable cells. Compounds 5 and 6 caused a modest increase in Nqo1 gene expression at 10 μM. The anti-inflammatory activity of xestoquinone (1) and monosubstituted analogues (4–6) may, in part, be mediated by Nrf2 activation, leading to attenuation of inflammatory mediators such as IL-1β and NOS2.
Samples were collected under gratuitous permit numbers GP-0084-15 and GP-0123-17, issued by the Department of Agriculture of the Philippines. We thank the municipalities of Bolinao, Pangasinan, and Puerto Galera, Oriental Mindoro for permission for sample collection. We acknowledge assistance from Z. L. Malto and DDHP chemical ecology group in obtaining the mass spectrometric data and sample collection, respectively.
Are Pyrodinium blooms in the Southeast Asian region recurring and spreading? A view at the end of the millennium
Azanza, Rhodora V.; Max Taylor, F. J. R. (Royal Swedish Academy of Sciences, 2001-09)
Pyrodinium bahamense (var. compressum) has been the only dinoflagellate species that has caused major public health and economic problems in the Southeast Asian region for more than 2 decades now. It produces saxitoxin, a suite of toxins that cause Paralytic Shellfish Poisoning (PSP). A serious toxicological problem affecting many countries of the world, mild cases of this poisoning can occur within 30 minutes while in extreme cases, death through respiratory paralysis may occur within 2–24 hrs of ingestion of intoxicated shellfish. Blooms of the organism have been reported in Malaysia, Brunei Darussalam, the Philippines and Indonesia. The ASEAN-Canada Red Tide Network has recorded 31 blooms of the organism in 26 areas since 1976 when it first occurred in Sabah, Malaysia. As of 1999, the most hard hit country has been the Philippines which has the greatest number of areas affected (18) and highest number of Paralytic Shellfish Poisoning (PSP) cases (about 1995). Malaysia has reported a total of 609 PSP cases and 44 deaths while Brunei has recorded 14 PSP cases and no fatalities. Indonesia, on the other hand has a record of 427 PSP cases and 17 deaths. Studies on ecological/environmental impacts of these blooms have not been done in the region. Estimates of economic impacts have shown that the loss could be up to USD 300 000 day−1. Most of the data and information useful for understanding Pyrodinium bloom dynamics have come from harmful/toxic algal monitoring and research that have developed to different degrees in the various countries in the region affected by the organism's bloom. Regional collaborative research and monitoring efforts can help harmonize local data sets and ensure their quality and availability for comparative analysis and modeling. Temporal patterns of the blooms at local and regional scales and possible signals and trends in the occurrence/recurrence and spread of Pyrodinium blooms could be investigated. Existing descriptive and simple predictive models of Pyrodinium blooms can be improved and refined to help in the management of the wild harvest and aquaculture of shellfish in a region where the people are dependent on these resources for their daily food sustainance and livelihood.
Are seagrass growth and survival constrained by the reducing conditions of the sediment?
Terrados, J.; Duarte, C. M.; Kamp-Nielsen, L.; Agawin, N.; Gacia, E.; Lacap, D.; Fortes, M. D.; Borum, J.; Lubanski, M.; Greve, T. (Elsevier BV, 1999-11)
A literature review of the effects of the reducing conditions of the sediment on seagrass metabolism, growth and survival, and of the morphological and physiological adaptations that seagrasses show to cope with sediment anoxia is presented and major gaps in knowledge are identified. The hypothesis that sediment anoxia controls the survival of seagrasses was tested experimentally by increasing the oxygen demand of the sediment with the addition of sucrose. Experiments were performed in a tropical (Southeast Asia) multispecific seagrass meadow, a Mediterranean Cymodocea nodosa meadow, and a temperate Zostera marina meadow. Sulfide levels in pore water and vertical redox profiles were used to characterise the effects of the sucrose additions on the sediment, while plant responses were quantified through the changes in shoot density and leaf growth. Sulfide levels in pore water increased and sediment redox potential decreased after the addition of sucrose to the sediment of different seagrass meadows. The effect of the addition of sucrose to the sediment of seagrasses was species-specific. Leaf growth was reduced and shoot mortality increased in some of the tropical species (e.g., Thalassia hemprichii), but not in others. Neither mortality nor leaf growth of the Mediterranean species C. nodosa was affected by sucrose additions, and only leaf growth was reduced two months after the addition of sucrose in Z. marina. Our results suggest that increased sediment anoxia might be a factor promoting growth inhibition and mortality in seagrasses, although strong differences have been found among different species and environments.
Aspects of the growth, recruitment, mortality and reproduction of the scallop Amusium pleuronectes (Linné) in the Lingayen Gulf, Philippines
Del Norte, A. G. C. (Informa UK Limited, 1988-11)
Growth, recruitment, mortality and reproduction were investigated in the Asian moon scallop, Amusium pleuronectes (Linne) from the Lingayen Gulf, Philippines. Allometric relationships were defined by comparing different shell dimensions, as well as body weight proportions including total weight with shell, visceral weight, adductor muscle weight and gonad weight. Use of the von Bertalanffy-based ELEFAN I program yielded estimates of growth parameters equivalent to H ∞ = 106Dimshell height and K = 0.92 per year, with approximate longevity for the species of about 2 years. Recruitment, as derived using the ELEFAN II program, occurred throughout the year, but showed a pattern consisting of one major and one minor pulse separated by an 8- and 4-months interval. Fishing mortality (F = 5.3) was higher than natural mortality (M = 1.9). Spawning occurred throughout the year, with one major peak in February and one minor peak between July and September, thereby providing some biological basis to the recruitment pattern indicated. Protandry and size at sexual maturity (54 mm) in the species were confirmed.
Assessing the efficiency of microplastics extraction methods for tropical beach sediments and matrix preparation for experimental controls
Bonita, Jan Danielle P.; Gomez, Norchel Corcia F.; Onda, Deo Florence L. (Frontiers Media SA, 2023-11-03)
Introduction: Microplastic pollution has become a global issue, eliciting attention not just from the scientific community but also both from the public and governmental bodies. Drawing data-driven policies and interventions, however, remain difficult due to the severely lacking baseline information from different environments such as beaches. One of the challenges in doing baseline studies is the lack of harmonized methodologies that will allow for comparison of results, integration of data, and its effective translation to evidence-based policies. Emphasis on quality control measures among baselining efforts through the proper implementation of experimental controls is also lacking. Methodology: To address these gaps, we compared methodologies for preparing the sediment matrix for experimental controls, as well as evaluated protocols for extracting microplastics from tropical beach sediments. Beach sediments were collected, dried, sieved, and spiked with known amounts of microplastics of different polymer types. The removal and extraction efficiencies of the protocols being compared were evaluated. Results and discussion: Our results showed that subjecting beach sediments to a furnace at 550° C for 4 hours is the most efficient way to remove plastic contamination, implying its applicability for preparing experimental controls. Meanwhile, a modified version of Masura et al. (2015), one of the widely cited methodologies for microplastics extraction, exhibited the highest mean extraction efficiency (99.05 ± 0.82%) among the protocols being compared. Results of this work will be useful in identifying methods that can be adopted and utilized for research and baselining efforts not just in the Philippines but also in Southeast Asia. This will also be helpful in the harmonization of methods, data reporting, and even skills as implemented through the regional and national action plans to address marine plastic pollution.
The authors would like to thank the members of the Microbial Oceanography Laboratory of the University of the Philippines, The Marine Science Institute, especially Mark Prudente and Kim John Balboa who provided assistance during the conduct of the experiment, and the staff and administrative personnel of the Bolinao Marine Laboratory.
Assessing the viability of commercial media for the mass culture of Chaetoceros muelleri
Cabanayan-Soy, Rona; de Peralta, Glycinea; Juinio–Meñez, Marie Antonette (National Fisheries Research and Development Institute, 2021-12)
The microalgae Chaetoceros muelleri is considered a highly nutritious feed for the cultured larvae of the tropical sea cucumber Holothuria scabra. Due to the cost of analytical grade culture media used in the production of C. muelleri, there is a need to evaluate cheap alternative commercial media to decrease the cost of producing quality live microalgal food. In this study, two different indoor batch culture systems (1 L glass bottles and 10 L plastic carboys) were used to evaluate the effectiveness of two conventional (modified F/2 and Walne’s) and one commercial (Epizyme AGP complete) microalgal culture media. Results of the 1 L glass bottle experiment showed that the peak cell density of C. muelleri in AGP (1,241 ± 116 x 10⁴ cells ml^-1) was not significantly different from the modified F/2 (1,584 ± 41 x 10⁴ cells ml^-1) and Walne’s medium (1,319 ± 162 x 10⁴ cells ml^-1) (Kruskal-Wallis test, p=0.78). Likewise, in the plastic carboy experiment, the maximum cell density of C. muelleri in Walne’s medium (750 ± 144 x 10⁴ cells ml^-1) and F/2 medium (653 ± 79 x 10⁴ cells ml^-1) were higher, but not significantly different from AGP (496 ± 184 x 10⁴ cells ml^-1) (Kruskal-Wallis test, p=0.43). The highest growth rate in the glass bottle cultures was the modified F/2 (0.38 div day^-1), while AGP was the lowest (0.34 div. day^-1). On the other hand, in carboy culture, AGP was higher (0.17 div.day-1) compared to modified F/2 (0.15 div. day^-1) and Walne’s medium (0.13 div. day^-1). The exponential growth phase was similar in the glass bottles, while in the carboy, the exponential phase was reached at a shorter time in the AGP treatment than those in the modified F/2 and Walne’s media. The findings showed that AGP medium is an adequate alternative to replace the conventional media (modified F/2 and Walne’s) during the secondary stock culture for C. muelleri. The viability of using cheaper and more readily available commercial AGP media for the indoor culture production of C. muelleri can contribute to cost-effective scaling-up of the hatchery production of quality H. scabra larvae and early juveniles.
The authors would like to thank Dr. Rene Abesamis for his valuable comments and the two anonymous reviewers for their suggestions to improve the manuscript. We are also grateful for the guidance of Ms. Elsie Tech in improving the microalgal cultures and providing valuable inputs for this paper. We also thank the Sea Cucumber Research Team and the staff of the University of the Philippines - Marine Science Institute, Bolinao Marine Laboratory for their support and assistance during the conduct of the study. We would also like to acknowledge the Department of Science and Technology Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development (DOST-PCAARRDQSR-MR-CUC.02.02) and the Australian Centre for International Agricultural Research (ACIAR – FIS/2003/059) for the financial support in the conduct of this study.
Associated effects of shading on the behavior, growth, and survival of Stichopus cf. horrens juveniles
Rioja, Rose Angeli; Palomar-Abesamis, Nadia; Juinio–Meñez, Marie Antonette (Springer Science and Business Media LLC, 2021-07-07)
Stichopus cf. horrens is an emergent culture species. It is known to be nocturnal and negatively phototactic; hence, determining its behavioral and growth responses to different light regimes is essential in optimizing culture protocols. This study examined the interactive effects of shading and relative food availability on the feeding pattern, absolute growth rates, and survival of juvenile S. cf. horrens. Six-month-old juveniles (4.27 to 19.41 g) were reared in replicate aquaria with three different shading treatments (covered, exposed, and half-covered aquaria) under ambient light conditions for 30 days. Juveniles in the exposed treatment with high microalgal biomass (13.44 ± 4.57 mg/g) had the highest growth rates (0.10 ± 0.05 g/day) but also the highest mortality (50%). In contrast, juveniles in the covered treatment had the lowest growth (−0.07 ± 0.03 g/day) but the highest survival (100%). Growth rates in the half-covered treatment were comparable with the exposed, and survival was higher than in the covered treatment. These indicate a trade-off between growth associated with more food and mortality risks due to light-induced stress. Juveniles in the half-covered treatment showed a significant preference to stay in the shaded portion whenever they were inactive during the day, suggesting avoidance to high light intensities (4726.51 ± 1582.43 Lux). Results of this study suggest that careful calibration of light intensities in nursery systems may help enhance juvenile growth. For indoor systems that may have limited space or surfaces for microalgal growth, cultured benthic diatom can be added to the partially covered tanks to increase the food available for the juveniles.