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    • Conference paper

      Breeding and culture of the polychaete, Marphysa mossambica, as feed for the mud crab 

      VR Alava, JB Biñas & MAE Mandario - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Marine worms (Annelida: Polychaeta) are considered as important food for crustacean broodstock because they contain hormones and correct balance of essential nutrients for reproduction. Marphysa mossambica (Peters, 1854) occurs in muddy coastal areas and is abundant in fish farms where it builds burrows in nutrient-rich sediments. This species encapsulates their eggs and larvae in gelatinous masses (jelly cocoons). It is a multiple spawner, and breeders are repeatedly spawning in tanks. Culture techniques have also been developed and established in tanks. Based on dry weight, cultured M. mossambica contained 62-66% crude protein and 7-12% lipids with levels of highly unsaturated fatty acids (HUFAs) such as arachidonic (20:4n-6), eicosapentaenoic (20:5n-3) and docosahexaenoic acid (22:6n-3) at 0.2-0.5%, 0.2-0.3% and 0.3-0.5%, respectively. Stocks were monitored for the presence of white spot syndrome virus (WSSV) using polymerase chain reaction-based diagnostic methods. The WSSV-free polychaetes mass-produced in tanks were utilized as live food for mud crab S. serrata broodstock. Mud crab broodstock fed natural food (mussel, fish, and squid) with live Marphysa on daily feed rotation produced higher number of crab zoeae, larval survival, total lipids and HUFAs than those fed natural food without live Marphysa. Production of nutrient-rich WSSV-free polychaetes in captivity can play a significant role in supporting crustacean hatcheries that supply seeds to the nursery and grow-out.
    • Conference paper

      Evaluation of the bioremediation capacity of the polychaete, Marphysa mossambica (Peters, 1854) in pond sediments 

      MAE Mandario, VR Alava & NC Anasco - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Marphysa mossambica is commonly found in brackishwater ponds and is an important natural food for cultured stocks particularly mud crabs. To understand the burrowing activity of polychaete, survival and capacity to bioremediate pond sediments, tank experiments were conducted. In a completely randomized design with three replicates per treatment, small (1-month old, 28 mg) and large (3-month old, 139 mg) hatchery-bred M. mossambica were reared in two sediment types for 30 days without feeding. Aeration was supplied and water change was done every other day. Polychaete-free sediments served as control. Sediments obtained from SEAFDEC/AQD Dumangas Brackishwater Station were sun-dried, ground and passed through 1-mm sieve.

      Initial sediment A had 1.86% organic matter, 1,171 ppm available sulfur (SO42-), 194.23 ppm iron (Fe) and 7.86 pH while initial sediment B contained higher organic matter (4.1%), available sulfur (2,456.67 ppm), similar iron level (199.34 ppm) and was more acidic (4.91 pH). In sediment A, small and large polychaetes did not differ (p>0.05) with the control in reducing organic matter but both significantly reduced (p<0.05) available sulfur (77-73%) and iron (69-71%). However, only the large polychaetes increased the pH (p< 0.05, 2.67%). In sediment B, only the large polychaetes reduced (p<0.05) organic matter (27%) but both small and large polychaetes significantly reduced (p<0.05) available sulfur (64-70%) and iron (70-74%). The pH increase was similar to control (17-24%). Large polychaetes had higher survival (93%, p<0.05) than small polychaetes (60%) in sediment B but not different (p>0.05) in sediment A (97%, 87%). The study demonstrated the bioremediation capacity of M. mossambica particularly in reducing available sulfur and iron in sediments.