Challenge 04: Develop a sustainable and equitable ocean economy
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Ocean Decade
Challenge 04:
Develop a sustainable and equitable ocean economy
Generate knowledge, support innovation and multi-sectoral partnerships and develop solutions for equitable, resilient and sustainable development of the ocean economy under changing environmental, social and climate conditions.
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- Growth, nitrate uptake kinetics, and biofiltration potential of eucheumatoids with different thallus morphologiesNarvarte, Bienson Ceasar V.; Genovia, Tom Gerald T.; Hinaloc, Lourie Ann R.; Roleda, Michael Y. (Wiley, 2021-12-30)The declining production of commercially important eucheumatoids related to serious problems like increasing susceptibility to ice‐ice disease and epiphytism may be ameliorated by nutrition. This ushered to an increasing interest in incorporating seaweeds into an integrated multi‐trophic aquaculture (IMTA) setup to take up excess inorganic nutrients produced by fish farms for their nourishment. In this regard, it is important to understand the nutrient uptake capacity of candidate seaweeds for incorporation in an IMTA system. Here, we examined the growth, nitrate (NO3‐) uptake kinetics and biofiltration potential of Eucheuma denticulatum and three strains of Kappaphycus alvarezii (G‐O2, TR‐C16 and SW‐13) with distinct thallus morphologies. The NO3‐ uptake rates of the samples were determined under a range of NO3‐ concentration (1‐ 48 µM) and uptake rates were fitted to the Michaelis‐Menten saturation equation. Among the examined eucheumatoids, only SW‐13 had a linear response to NO3‐ concentration while other strains had uptake rates that followed the Michaelis‐Menten saturation equation. Eucheuma denticulatum had the lowest Km (9.78 ± 1.48 µM) while G‐O2 had the highest Vmax (307 ± 79.3 µmol · g‐1 · min‐1). The efficiency in NO3‐ uptake (highest Vmax/Km and α) was translated into the highest growth rate (3.41± 0.58 % · d‐1) measured in E. denticulatum. Our study provided evidence that eucheumatoids could potentially take up large amount of NO3‐ and fix CO2 when cultivated proximate to a fish farm as one component of an IMTA system. During a 45‐d cultivation period of eucheumatoids, as much as 370 g NO3‐ can be sequestered by every 1 kg initial biomass E. denticulatum growing at 3% · d‐1. Furthermore, based on our unpublished photosynthetic measurements, the congeneric K. striatus can fix 27.5 g C · kg‐1 DW during a 12‐h daylight period.
- Sargassum sp. juice as an early juvenile supplemental feed for Stichopus cf. horrensIbañez, 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.