Masters Theses
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Item Removal of Harmful Algal Bloom (HAB)-forming organisms using ball clay: Factors and effects of clay additionRivera, Peter Paolo L. (Marine Science Institute, College of Science, University of the Philippines Visayas, 2015-05)Global concern for Harmful Algal Blooms (HABs) has increased due to their frequency of occurrence and associated negative health and economic effects. Control measures for HABs/red tides have been developed to alleviate their effects in the marine and coastal environments. The use of clays and modified sands/sediments to remove/control HABs is one of the promising and attractive direct control options for areas with persistent HAB problems. However, factors such as pH and ionic strength and mechanisms and kinetics of algal removal through clay addition/spreading are not fully understood. This study 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. compression, Gymnodinium catenation, and Alexandrium tamarense complex. High REs by ball clay were observed on Pyrodinium and Gymnodinium. On the other hand, only minimal removal was observed with Alexandrium. This implies that ball clay has a varying affinity towards different HAB species. Removal was also found to be highly dependent on bloom stages and varies for a given target species. RE of ball clay for the three test organisms increases as the pH of the solution decreases (83.1% for Pyrodinium, 81.2% for Gymnodinium, 89.4% for Alexandrium at pH 6. Results from this study show that with increasing salinity and/or ionic strength, RE also increases (82.7% for Pyrodinium, 88% for Gymnodinium, and 79.5% for Alexandrium at ionic strength of 1.0). Results show that changing the pH and ionic strength influenced the zeta potential (electrokinetic potential) of both the toxic algal cells and ball clay, hence affecting algal flocculation and leading to the effective removal of the algal cells. Microalgal cells are negatively charged in growth media at pH values (7-9 for most algal species) typical for growth and the charges cause adjacent cells to repel each other and remain suspended in the medium. The negative charges apparently derived from the water and dissociation of functional groups on algal cell walls, and vary among different algal species. The changes in pH influence the degree of surface dissociation, thus affecting the cell surface charge. The zeta potential of ball clay as a function of varying ionic strength and salt concentrations showed that zeta potential decreases (more negative) with increasing ionic strength from 0 to 1 and/or salinity from 0 to 36 ppt (in contrast to algal cells). When the ionic strength of the solution is increased, the charge potential difference between clay particles and algal cells also increases, thereby increasing the affinity between the two particles. Cell death and lysis were evident within the suspended and settled clay matrix from direct microscopic observation. The cells appeared moribund, and stained cytoplasmic material could be seen leaking into the medium. Cell death may have been due to the direct physical contact between the cells and clay particles. Cell lysis occurred over a 1–2-hour period in single-species cultures of HAB organisms. Measurement of fluorescence properties through confocal laser scanning microscopy (CLSM) of microalgae has proven that a rapid and sensitive ecotoxicity method could be developed where the motility and viability of cells flocculated with clay could be examined. The substantial release of the nucleotides and intracellular materials from the algal cells indicates the expulsion of the thecal plates and cell membrane leading to the disintegration of the algal cells upon clay addition. Cellular damage was further confirmed by metabolic imaging through an esterase activity assay. Esterase activity in control and treated cells was studied by fluorescence imaging after staining with fluorescence diacetate (FDA), a technique to probe cell membrane integrity and cell viability. FDA-positive cells decreased through time until 24-hour upon exposure to ball clay. Future studies are needed to investigate the actual mechanism of how clay induces cell lysis or mortality. Cell mortality may be due to natural senescence or programmed cell death (PCD) under stress-promoting conditions and not related to any chemical or physical interaction between the clay and the algal cells. It is also interesting to look at the possible formation of ecdysal and temporary pellicle cysts upon clay treatment. The possible formation of temporary cysts by HAB cells may play a role in bloom regrowth. The encystment and excystment may enable HAB cells to escape entrapment, allowing a bloom to reform.Item Effect of elevated carbon dioxide and phosphorus on nitrogen uptake, lipid content, and growth of Tetraselmis sp.Ferriols, Victor Marco Emmanuel N. (Institute of Aquaculture, College of Fisheries and Ocean Sciences, University of the Philippines Visayas, 2011-04)Effect of elevated carbon dioxide (CO2) and phosphorus levels on nitrogen uptake, lipid content, and growth of Tetraselmis sp. were investigated. Cultures of Tetraselmis sp. were added with CO2 and phosphorus at concentrations above those currently used in aquaculture practices in a factorial experiment. Three levels of CO2 (no addition, 5% v/v, and 10% v/v of the incoming air for aeration) and three levels of phosphorus added as NaH2PO4 (5, 10, 20 mg L’1) in modified F medium with NH4+ as the primary nitrogen source were used. Optical density (680 nm) and residual NH3-N in the culture medium were monitored daily over a culture period of 6 days. Relative growth rate (k'), nitrogen uptake (pg NH3-N cell’1 day1), and lipid content (% dry weight) were calculated and determined at the end of the culture period. No interactive effect between phosphorus and CO2 levels was observed in all variables measured (p > 0.05). Highest growth rate (k = 1.82±0.04), nitrogen uptake (0.316±0.008 μg NH3-N cell1 day1), and lipid content (10.95±0.15 %DW) were exhibited at 10% CO2 supplementation. Growth and nitrogen uptake were similar in treatments with elevated levels of phosphorus, but lipid yield (9.41±0.27 %DW) was lowest at 20 mg L1 of phosphorus supplementation (p < 0.05). These results showed the critical role of CO2 in nitrogen uptake, lipid content, and growth of Tetraselmis sp. It also indicates the potential of this algal species for waste water remediation, biofuel production, and carbon sequestration.Item Effects of sodium Iodine -enriched brine shrimp (Artemia salina) on the growth, survival and metamorphosis of Rabbitfish (Siganus guttatus) bloch larvaeLegaspi, Ma. Irene C. (Institute of Aquaculture, College of Fisheries and Ocean Sciences, University of the Philippines Visayas, 2018-06)Metamorphosis is considered the most crucial stage in larval fish development that dictates the overall larval fish survival and production output in a hatchery system. This physiological process is modulated by thyroid hormones produced from the thyroid gland the biosynthesis of which is dependent on the supply and availability of the mineral iodine. The present study evaluated the supplementation of iodine to rabbitfish (Siganus guttatus) larvae to determine the influence of this mineral on thyroid hormone levels, metamorphosis, growth performance, stress tolerance, and survival. To efficiently deliver iodine to the larvae, the enrichment protocol was optimized by exposing the Artemia to increasing concentrations of this mineral (0.05 g L-1,0.1 g L-1, 0.2 g L-l, 0.4 g L-1 and 0.8 g L-1). The best iodine enrichment treatment was selected (0.8 g NaI L-1) and used to evaluate the influence of this mineral on larval development, growth, metamorphosis, stress tolerance, and survival. Results suggest that growth of rabbitfish in terms of body weight was higher in the treated group (0.20±0.01g) as compared to the control group (0.14±0.01g). This significant growth response is associated with accelerated period of metamorphosis by 11.2 days and a lower muscle fiber count in the treated group (0.003±0.005 μm2-1). Higher levels of triiodothyronine (T3) and thyroxine (T4) were also observed in the group receiving the iodine-enriched Artemia that coincides with the larvae’s accelerated period to metamorphose. T3 in the treated group (15.31±1.22 ng g-1) is higher compared with the control (8.67±1.5 ng g-1) and T4 in the treated group (459.25±136.9 ng g-1) is also higher compared with the control group (170.86±92.55ng g-1) at 27 days after hatching which coincides with the onset of metamorphosis leading to early metamorphosis of larvae in the treated group. In addition, the present results showed that the larvae in treated group were significantly tolerant to stress, quantified as the cumulative stress index (15.33±2.40 CSI) indicating the positive response of the larvae to the dietary iodine enrichment. In summary, sodium iodide-enriched live food (Artemia) accelerated rabbitfish larvae metamorphosis, improved growth and stress tolerance in rabbitfish larvae. The results of this study can be used as a model iodine enrichment protocol to improve the hatchery output of other high-valued marine fish species in culture.Item Quality changes in Tilapia (Oreochromis niloticus) after delayed icing and subsequent storage in ice.Saluan-Abduhasan, Fathma (University of the Philippines Visayas, 1985-04)Quality changes in tilapia (Oreochromis niloticus) iced directly on harvesting were compared to those occurring when icing was delayed. Chemical and sensory examinations showed that the shelf life of tilapia was 26 days when iced immediately. 20 days and 15 days with 4 and 8 hours delay, respectively.Fish kept at ambient temperature for 12 hours were rejected after one day in ice. These results suggests that for every hour delay in icing the effective shelf life is reduced by approximately one day up to the 8th hour delay. Total volatile nitrogen values increased with storage time. Likewise, K-value and hypoxanthine values increased as storage time increased. The initial bacterial load ranged from 103- 104 cfu/g of fish with H2S-producers count of less than 100 cfu/g of fish. At rejection, the microbial load was 108-109 cfu/g of fish with H2Sproducers count of 106-107 cfu/g. The typical off odours of naturally spoiling fish have been reproduced in blocks of sterile muscle by organisms such as Alteromonas putrefaciens, Pseudomonas sp, Pseudomonas maltophilia, Pseudomonas flourescens and pseudomonas stutzeri.Item The effect of sex reversal treatment on the growth and survival of two strains of Nile tilapia (Oreochromis niloticus) and Mossambique tilapia (Oreochromis mossambicus) raised in brackishwaterBadillo, Susan Delos Santos (University of the Philippines Visayas, 2000-08)A study to determine the effects of sex reversal (SRT) on the growth and survival of two strains of Nile tilapia (Oreochromis niloticus) and Mossambique tilapia (Oreochromis mossambicus) was conducted in four 2m x lm x 1.5m suspended hapa nets in UPV-IA Hatchery and Biology brackishwater fishpond for 75 days. The experimental treatments and codes used in this study were the following, Treatment GGn (GIFT/normal), Treatment GGsrt (GIFT/sex reversal), Treatment MMn (Moss/normal), Treatment MMsrt (Moss/sex reversal), Treatment GEn (GIFT-Egypt/normal) and Treatment GEsrt (GIFT-Egypt/sex reversal). Juvenile fry (average weight 0.0 1g) were subjected to sex reversal treatment by feeding fish diet with methyltestosterone at 60 mg per kg of feed for three weeks in freshwater. After SRT, the fingerlings were nursed in fine mesh net (0.5 mm mesh, 2m x 1m x 1m) for 30 days until the fish attained the weight from 3.0 g to 5.3 g. They were individually tagged by fin clipping method. They were acclimated from 0 ppt to 20 ppt prior to experimental proper. Juvenile fish of 3.40-5.44 g were communally stocked at 25 fish each treatment. Juvenile fish were fed with a commercial feed at 15% of their mean body weight per day from 1-30 days and 10% per day of their mean body weight from day 31-75 days culture period. Within the normal treatments, there was no significant (P>0.05) difference in mean body weights between Treatments GGn and GEn but both are significantly higher (P<0.01) than Treatment MMn. Within the sex reversed treatments, mean body weight in Treatment GGsrt was not significantly (P>0.05) different from Treatment GEsrt, but showed high significant (P<0.01) difference with Treatment MMsrt, similar to the normal treatments. The highest average final biomass of 808.88 g was obtained in Treatment GGsrt followed by Treatment GEsrt (795.58 g) and lowest in treatment MMn (367.63 g). The biomass gain of tilapia within the normal treatments ranged from 282.6 g to 672.95 g. Treatment GGn showed no significant (P>0.05) different from Treatment GEn, but both were significantly higher from Treatment MMn. The same trend was observed within sex reversal treatments. Treatment GGn obtained the highest (589.70%) percentage biomass gain and Treatment MMn (335.01%) was the lowest within the normal treatments. In sex reversal treatment, Treatment GGsrt has no significant difference with Treatment GEsrt, but both showed a high significant difference in Treatment MMsrt. Highest specific growth rate was observed in Treatment GGn (2.62 g day-1) and lowest in Treatment MMn (1.97 g day-1). Mean condition factor (MCF) of tilapia was highest in Treatment GGn (1.60), followed by Treatment GEn (1.56) and lowest in Treatment MMsrt (1.17). Within the normal treatments, Treatment GGn and GEn showed no significant difference (P>0.05), but both were significantly higher (P<0.01) than Treatment MMn. Within the SRT treatment, all treatments showed highly significant (P<0.01) difference from each other with highest at Treatment GGsrt and lowest at Treatment MMsrt. Mean survival ranged from 95% to 100%. Highest percent male population was obtained in hormone-treated fish (95-100%) compared to normal treatments (64-71%). Sex reversal treatment did not improve growth and survival of the two strains of Nile tilapia (O. niloticus), but improved the growth of Mossambique tilapia (O. mossambicus) significantly after 75 days under the conditions this experiment was conducted.Item Nursery and grow-out culture of mangrove polychaete Marphysa sp.Caballero, Pedrita A. (University of the Philippines Visayas, 2019-12)Experiments on the polychaete Marphysa sp. were conducted to determine the optimum stocking density in indoor nursery as well as the optimum stocking density and culture period in outdoor grow-out ponds that can maximize polychaete biomass production. In the nursery experiment, early metatrocophores at four stocking densities (10,000 m-2; 20,000 m-2; 30,000 m-2; and 40,000 m-2) were tested to determine growth (number of chaetigerous segments) and survival after 7 days in nursery cups. Results showed that the number of segments of early juveniles did not vary significantly (P>0.05) in all treatments. Final number of survivors were higher (P<0.05) at 40,000 m-2 (33,700 ± 1,488 ind.) than 10,000 m-2 (8,300 ± 1,097 ind.), 20,000 m-2 (16,100 ± 1,095 ind.) and 30, 000 m-2 (26,800 ± 1,489 ind.). This suggests that Marphysa sp. juveniles can be produced in high numbers despite high stocking densities using the current nursery protocols. The outdoor grow-out experiment was conducted in a brackishwater pond where early juveniles were stocked at four densities(500 m-2; 1,000 m-2; 1,500 m-2; and 2,000 ind.m-2) attwo culture periods (3 and 4 months) to determine the survival and growth of Marphysa sp. Results revealed that stocking density of 500 ind.m-2 resulted in bigger (P<0.05) polychaetes but total length, survival rate, and biomass were not different (P>0.05) from those in higher stocking densities. Survival rates of the polychaetes did not differ significantly (P>0.05) between 4 months (18.1 ± 12.1%) and 3 months(16.1± 9.2%) of culture. Body weight, total length, and polychaete biomass were all significantly higher (P<0.05) after 4 months of culture compared to just 3 months, suggesting longer culture periods can improve overall yields. The organic matter in sediments decreased from 5% to 4% both in treatments for stocking densities and culture periods, indicating the potential of Marphysa sp as a bioremediation agent.Item Production and bioactivity characterization of protein hydrolysate from Portuguese oyster (Crassostrea angulata)Gomez, Honey Lyn R. (University of the Philippines Visayas, 2019-06)It has been shown that oysters represent diversified peptides with a variety of biological importance. In the present study, the use of proteomics techniques and bioinformatics tool was carried out to predict the potential bioactivities of Portuguese oyster (Crassostrea angulata). Mascot database search have identified 8 proteins from C. angulata and 5 of which were selected for in silico analysis. Interestingly, BIOPEPUWM database analysis predicted that pepsin (pH > 2) can theoretically release highest number of peptides with biological activities, predominantly angiotensin-1 converting enzyme (ACE) and dipeptidyl peptidase (DPP-IV) inhibitory activities, followed by stem bromelain and papain. To confirm the reliability of these predictions, C. angulata proteins were assessed in vitro. Results showed that all the hydrolyzed samples possessed inhibitory effect against ACE and DPP-IV, with pepsin hydrolysate (PEH) having the strongest activity of 78.18% and 44.34%, respectively. Further fractionation of PEH revealed that fractions with low molecular weight (MW) such as <1 kDa fraction (Fl) and 1-5 kDa fraction (F2) can demonstrate higher ACE and DPP-IV inhibitory activity compared to crude PEH and >5 kDa fraction (F3), but not to a great extent. Overall, the results obtained from in vitro analyses corresponded with the in silico predictions. Findings of this study thereby suggest the applicability of in silico technique for rapid and reliable identification of bioactive peptides from food proteins and determination of suitable enzyme capable for the release of these peptides. Moreover, proteins from C. angulata can be considered as potential sources of peptides with potential pharmaceutical and nutraceutical application.Item Does a coral reef enhance the productivity of its surrounding waters?Peñafiel, Christen P. (University of the Philippines Visayas, 2019-06)Coral reefs have long been assumed and continually claimed to be origins of very high productivity, but how they attract organisms from and export nutrients to their neighboring waters remains largely unknown. Specifically, this study aimed at determining the space-time dynamics of nutrients and biomass redistribution around Hibotkan Rock Sanctuary (HRS), Banate, Iloilo, a sanctuary reef established by Municipal Fisheries Ordinance No. 12 covering an area of 25 ha. Twelve (12) sampling stations were established for space-time nutrient profiling, phytoplankton count, and supplementary measurements of water parameters, and four (4) stations for fish (biomass) visual survey. Results were analyzed using spatio-temporal plots and the Pearson correlation matrix (5% significant level). Nitrite was observed to be limiting, while nitrate was the most abundant in the waters of HRS. The predominant temporal variations of nutrients followed the flood tide (FT) and ebb tide (ET) cycles. In general, the tidal current direction appeared to control the redistribution of the nutrients (NO3-, NO2-, PO43-, and SiO44-). This study further revealed that stations of high nutrient concentration usually coincided with low levels of dissolved oxygen (DO). Species of fish observed were all indigenous and well-known inhabitants of the coral reefs. Furthermore, no other families of fishes (such as those of commercial value) were caught on record. Overall, there was no clear indication of import or export of living biomass in the HRS area. It can be inferred from the results that the fabled high productivity of coral reefs has no clear scientific basis; consequently, the Marine Protected Areas (MPAs) concept also appears to have no solid foundation.Item Effect of different bio-augmentation agents on the biochemical composition of bacterial floc and growth of juvenile Penaeus monodon cultured in concrete tanksDianala, Rex Delsar B. (University of the Philippines Visayas, 2012-10)The effect of bio-augmentation agents on the biochemical composition of biofloc, growth ofjuvenile Penaeus monodon, and antimicrobial activity of BFT water against Vibrio harveyi was investigated. P. monodon juveniles were cultured in pond soil-lined concrete tanks for 150 d using biofloc technology with bio-augmentation. Three commercial bio-augmentation agents (Pond Protect™, Pond Dtox™, BZT Waste Digester™) were tested against a control with no bio-augmentation agent application. At the end of the culture period, floc and shrimp collected for proximate analysis, and biofloc water tested for activity against V. harveyi. Average body weight (ABW), food conversion ratio (FCR), and specific growth rate (SGR) of the shrimp were computed. Bio augmentation with Pond Protect™ resulted in significantly higher (p < 0.05) crude protein content of the biofloc although this did not translate to higher shrimp yield nor growth performance. BZT Waste Digester™ as bio-augmentation agent significantly increased (p < 0.05) shrimp ABW. No apparent relationship between floc composition and shrimp carcass composition was observed. BFT water, with and without bioaugmentation agents, completely inhibited V. harveyi within 24 h. This study demonstrates that bio-augmentation agents could enhance the biochemical composition offloc and affect shrimp growth. BFT water was also shown to have potent antimicrobial properties against V. harveyi.Item Survival of nursery-reared juvenile milkfish, Chanos-chanos at different transport density, temperature and anaesthetic combinationsFailaman, Alan N. (University of the Philippines Visayas, 2020-06)Experiments were conducted to optimize transport conditions of nursery cultured juvenile milkfish in a closed plastic bag based transport system. In the first experiment combined effects of temperature (25-27°C, 20-22°C and 15-17°C) and anesthetics (2-phenoxyethanol at 200 mgL-1 for initial sedation and 80 mgL-1 for transport sedation) on oxygen consumption and survival ofjuvenile milkfish, Chanos chanos, were evaluated. Another experiment was conducted to optimize transport conditions at fish densities of 200, 400, 600, 800 and 1000 gL-1 for 4, 8, 12,16 and 20 hour duration. The study showed no significant difference on oxygen consumption rates ofmilkfishjuveniles subjected to various water temperature range and anesthetic combinations. Temperature range of 20 to 22°C in combination with anaesthetic (2-phenoxyethanol) application was the best condition for long duration confinement of milkfish juvenile in closed plastic transport bags. The study established the optimum juvenile milkfish transport density and the effective transport duration. With anaesthetic application (2-phenoxyethanol), juvenile milkfish density of 600 gL-1 is effective for 20 hours oftransport duration, 800 gL-1 for 8 hours oftransport duration and 1000 gL-1 effective for 4 hours transport duration. These results provide a practical protocol for the transport of juvenile milkfish from the nursery culture area to the grow-out production area.