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    Temporal variation in the subtidal macroinfaunal composition of a NaGISA seagrass bed in southern Guimaras, Philippines between 2015 and 2016
    Bacabac, Earl Jeroh I. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2019-06)
    Seagrass meadows are amongst the most abundant and diverse ecosystems when it comes to biodiversity but due to stress induced by natural and anthropogenic factors, a worldwide decline threatens the vital ecological functions of these habitats. Studying the infauna provides clues and information about the complexity of seagrass ecosystems and provides information that would facilitate better seagrass area management and associated conservation efforts. The NaGISA sampling protocol was conducted in Calaparan seagrass bed in TINMAR, Guimaras, Philippines between Sept. 2015 and 2016. Overall macrofaunal density was recorded at 21,954.80 ± 36,109.62 ind.m'2 with macrofaunal density higher in 2015 than in 2016 albeit, insignificant except for capitellid polychaetes. Community structure analysis also found similarity in dominance patterns in the subtidal zone with other soft-bottom macrofaunal studies in the Philippines with polychaetes, nematodes, and crustaceans as the respective dominant macrofaunal groups observed. Dominant polychaete families were also found to be cosmopolitan and opportunistic. Granulometric analysis characterized the sediment as pebble to medium sand with mid phi values ranging from -3.69 to 1.10 but poor sorting in all sampling points was observed. Cymodoceaceans dominated the subtidal zone in both years (Halodule pinnifolia in 2015; Cymodocea rotundata in 2016). Correlation analysis showed macrofaunal densities to have a significantly strong negative relationship with sorting index and percent gravel while a strong positive relationship with percent seagrass cover. The poor sediment sorting, coarse sediment character, and seagrass cover were the primary factors influencing the observed decrease in macrofaunal density but the decrease is considered normal for the variability of macrofauna in the area. A clearer picture of macrofaunal interactions would be provided with comparison to intertidal macrofauna of the area in the sampling years and data on additional factors that were not measured in the study.
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    Relation of size and sex to the natural diet of the red crab Charybdis feriatus Linnaeus (Brachyura: Portunidae) from Pilar-Capiz Bays, Northern Panay
    Alabia, Irene Dolorfino (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2003-03)
    A total of 395 (males= 282; females=113) specimens of the red crab Charybdis feriatus were collected from Pilar-Capiz Bays from January-December 2002 and were used for the present study. Relative fullness index were computed for both sexes of different size classes. Results showed that stomachs of females were slightly fuller than that of males. Similar observation was made between juvenile and adult specimens. A total of 75 (males= 57; females= 18) gut contents were analyzed in detail. Major food items in the diet of the crabs include unidentified matter, unidentified eggs, fish, crab, and shrimp remains. Frequency of occurrence and combined visual estimation of unidentified organic matter were used for the examination. No dietary differences due to ontogenetic change were observed in the species while diet of male crabs were found to be more varied than those of females. However, frequency of occurrence of major food items in the stomachs of both sexes was comparable.
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    The effects of different salinity and organic matter levels on the growth of blue-green algae
    Bantillo, Rosario R. (University of the Philippines Visayas, 1983-03)
    A one-month culture of lab-lab to determine the growth of blue-green algae in three levels of salinity ( 15 ppt = S1, 30 ppt = S2 and 45 ppt S3) and two levels of organic matter (3.4 to 4.4% = OM1 and 6.5 to 7.8% = OM2) was conducted using a twenty-two plastic containers (diameter = 43 cm; height = 49 cm) at the University of the Philippines in the Visayas Brackishwater Aquaculture Center, Leganes, Iloilo. The study utilized a 3 x 2 factorial experiment in completely randomized design with three replicates. Organic matter levels of the soil affected the chemical properties of soil and water (available phosphorus, reactive phosphorus, ammonia-nitrogen and pH). The higher the organic matter level, the higher the pH and the concentrations of ammonia and phosphorus. On the other hand, salinity did not apparently affect the fluctuations in ammonia, phosphorus and pH due to water replenishment to maintain treatment levels of salinity. Earlier rapid growth of blue-green algae commencing on the 3rd to the 15th day was observed at higher organic matter level. While at lower organic matter level, this occurred only on the 18th to the 28th day. Blue-green algae population (units/ml) was observed highest in treatment IV (S1 OM2; 1,262,113) followed by treatments III (S3OM1 761,338); II (S2OM1; 514,788); I (S1 OM1 494,375); V (S2OM2; 413,750); and, the lowest was obtained from treatment VI (S3OM2; 394,275). The relative percentage proportion of blue-green algae in the lab-lab complex showed that it composed 17.7% in treatment IV, 16.86 % in treatment III, 16.64% in treatment II, 15.82% in treatment I, 15.2% in treatment V and 14.9% in treatment VI. These, however, did not significantlyvary among treatments. A low correlation coefficient (r) between the population count and the selected parameters: reactive phosphorus, water pH, soil pH and available phosphorus was obtained while a negative correlation was obtained between the population and ammonia-nitrogen. Significantly higher biomass (ash-free dry weight) of lab-lab was obtained in higher organic matter (OM2) and at 45 ppt salinity (S3). The highest biomass (ash-free dry weight) was obtained in treatment VI (S3OM2; 0.160 g/cm2) while the lowest was obtained in treatment I (S1OM1 0.012 g/cm2). The algal count of lab-lab also showed a significant difference in the organic matter levels but no significant difference on the salinity levels. The highest algal count was obtained in treatment V (S2OM2; 6,773,542 units/ml) and the lowest count was obtained in treatment II (S2 OM1; 2,328,792 units/ml). However, the primary productivity based on O2 production showed a significantly higher production in the lower organic matter and at higher salinity level (30 ppt.). The highest O2 concentration was obtained in treatment III (S3OM1 5.759 ppm) and the lowest was obtained in treatment V (S2 OM2; 4.19 ppm).