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Journal Articles - UP - MSI

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Author: search.filters.author.Baure, JerwinHas files: No

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    Community structure of periphytic diatoms in early-stage marine biofilms in a mariculture-impacted area
    Baure, Jerwin; San Diego-McGlone, Maria Lourdes; Juinio–Meñez, Marie Antonette (Science and Technology Information Institute, 2022-07-06)
    Periphytic diatoms constitute a major part of complex unicellular aggregations called marine biofilm or periphyton, of which little is known about in tropical marine environments. The early-stage community structure of periphytic diatom genera on two artificial substrates – glass slide and polycarbonate sheets was characterized. These artificial substrates were placed underwater for 6 d and examined on Days 1, 3, and 6 in four sites around Santiago Island, Bolinao, Pangasinan, Philippines, with different relative distances from the intensive milkfish mariculture area. Correlations of diatom community structures in these sites with physico-chemical factors were investigated. The five most abundant diatom genera – namely, Cylindrotheca, Nitzschia, Navicula, Amphora, and Pleurosigma – exhibited a weak correlation with nutrients. Less abundant genera Pseudonitzschia, Haslea, Bacillaria, Thalassionema, Rhizosolenia, Eucampia, Diploneis, Asterionellopsis, Chaetoceros, Bacteriastrum, Licmophora, Skeletonema, Lioloma, Thalassiosira, and Thalassiothrix showed a positive correlation with nutrients. Among sites, the highest benthic diatom cell densities (4.6 × 105 cells cm−2) after 6 d was found in Lucero. Generic richness and diversity varied among sites, with the highest diversity (H’ = 1.58) on Day 1 in Tomasa, the site nearest to the mariculture area, whereas the highest richness (D = 2.17–3.26) for all days and diversity (H’ = 1.38–1.52) for Days 3 and 6 were recorded in Silaqui, the most distal site. Generally, the highest diversity and richness were found on Day 1, which then decreased on succeeding days in all sites. The lack of a clear patternin community structure among sites relative to the proximity of these sites to the mariculture area may in part be attributed to the presence of other nutrient sources. Results of the study provide baseline information on the variability of periphytic diatom community structure in a mariculture-impacted area, and insights on how benthic diatoms may be used in monitoring the impacts of nutrient pollution.
    This work was supported by the Department of Science and Technology–Philippine Council for Agriculture, Aquatic, and Natural Resources Research and Development under Grant QMSR-MRRDMEC-295-1449. The authors would like to thank Tirso O. Catbagan and Garry R. Bucol for their assistance during field sampling, and Timothy James Cipriano for the site map. We would also like to thank the Marine Biogeochemistry Laboratory of the Marine Science Institute, University of the Philippines Diliman for providing environmental data.
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    Sargassum sp. juice as an early juvenile supplemental feed for Stichopus cf. horrens
    Ibañez, Glaiza; Cabanayan-Soy, Rona; Baure, Jerwin; Juinio-Meñez, Marie Antonette (Springer, 2022-09-28)
    The development of an efficient and low-cost feed is important to reduce the production and maintenance costs of microalgae. In this study, two experiments were conducted to evaluate the feasibility of using Sargassum sp. juice (SARG) to boost the growth and survival of post-settled Stichopus cf. horrens juveniles. Experiment 1 tested whether SARG improves growth compared with live microalgae diets, Chaetoceros calcitrans (Cc), combined Cc and Navicula ramosissima (Nr), and an unfed treatment. Experiment 2 determined the best SARG concentration—high feeding regime (HFR; 1 mL ind−1), medium (MFR; 0.5 mL ind−1), or low (LFR; 0.25 ml ind−1), relative to live microalgae Chaetoceros muelleri (CM). Juveniles in both experiments were reared for 30 days. In Experiment 1, the average daily growth rate (DGRL) of juveniles in SARG (0.04 ± 0.01 cm d−1) was the highest although not significantly different from Cc and Cc + Nr, but was significantly higher than the control. In Experiment 2, DGRL at day 14 in HFR (− 0.02 ± 0.02 cm d−1) was significantly lower than LFR (0.01 ± 0.01 cm d−1) and MFR (0.02 ± 0.02 cm d−1). Survival was higher in all SARG treatments compared with CM, while a significant decrease in feeding activity was observed in HFR by day 30. Results indicate that concentrations of 0.25–0.5 mL SARG per juvenile can boost growth and be an alternate diet for post-settled juveniles during early rearing. However, SARG alone is not sufficient to maintain growth beyond 3 weeks. With SARG feed supplementation and water quality management, the scaling-up of juvenile production of this emergent culture species can be accelerated.
    Our sincere gratitude to Mr. Tirso Catbagan and Mr. Garry Bucol for their assistance in the set-up of the experiments. We also thank Ms. Rose Angeli Rioja and Ms. JayR Gorospe for providing inputs to improve 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.