Population dynamics of the calanoid copepod, Acartia tsuensis in a brackish-water pond in the Philippines
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CitationGolez, M. S. N., Ohno, A., Toledo, J. D., Tanaka, Y., & Ishimaru, T. (2002). Population dynamics of the calanoid copepod, Acartia tsuensis in a brackish-water pond in the Philippines.
PublisherThe Japanese Society of Fisheries Science
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Effect of some vertebrate and invertebrate hormones on the population growth, mictic female production, and body size of the marine rotifer Brachionus plicatilis Müller Eight vertebrate and invertebrate hormones were screened for their effect on population growth, mictic female production, and body size of the marine rotifer Brachionus plicatilis. Growth hormone (GH) or human chorionic gonadotropin (HCG) at 0.0025-25 I.U. ml-1 and estradio1-17β (E2), triiodothyronine (T3), 20-hydroxyecdysone (20-HE), 5-hydroxytryptamine(5-HT), gamma-aminobutyric acid (GABA) or juvenile hormone (JH) at 0.05-50 mg l-1 were added to 5-ml of Nannochloropsis oculata suspension (7 x 106 cells ml-1). From an initial density of 1 individual ml-1, rotifers were cultured with hormones for 48 hours in 22 ppt seawater at 25 °C, in darkness. Rotifers were counted and classified into female types and transferred to a new algal food suspension without hormone every other day until day 8 when body size was measured. Population growth was significantly higher in treatments exposed to GABA (50 mg l-1), GH (0.0025 and 0.025 I.U. ml-1), HCG (0.25 and 2.5 I.U. ml-1), and 5-HT (5 mg l-1). E2 caused a decrease in population growth, whereas JH, 20HE, and T3 had no effect. Mictic female production was significantly higher at 0.05 and 0.5 mg l-1 JH and 0.05 and 5 mg l- 5HT. GH (0.0025 and 0.025 I.U. ml-1), E2 (50 mg l-1 ), GABA (0.5, 5 and 50 mg l-1), and 20-HE (0.05 mg l-1) treatments had significantly higher mictic female production only on day 8, 6, 4, and 6, respectively. T3 and hCG had no effect on mictic female production. Lorica length increased by 9.6% and 4.4% in rotifers treated with JH (0.05 mg l-1) and GABA (5 mg l-1), respectively. Correspondingly, lorica width increased by 8.9% and 2.6% in these treatments. In comparison, 20-HE-, T3-, and HCG-treated rotifers were smaller (3.9-8.2%) and GH, 5-HT and E2 had no effect on rotifer body size.
Conference paperJH Primavera - 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 CenterThe paper reports the use of mangroves by Scylla species both as wild and culture habitats. Based on published literature, natural mangrove crab populations are described in terms of population density, dispersal and movement within and outside mangroves, crab burrows and associated mangrove species. Strategies for Scylla conservation depend on the kind of mangrove habitat - (mangrove) restoration for open fringing mangroves where crab recruitment and abundance are determined by habitat availability vs stock enhancement in closed basin mangroves with restricted recruitment and limited movement of crabs. Mangrove crabs are also reared in monoculture in mangrove cages and pens, or in polyculture with milkfish in extensive ponds (where mangroves used to thrive). The paper describes a SEAFDEC Aquaculture Department study to evaluate the effects of mud crab net pen systems on mangrove macroflora, and the replacement of dietary trash fish with low-cost pellets. Results showed that incomplete, low-cost pellets can replace fish biomass requirement in mud crab diets, but that crab presence resulted in fewer mangrove seedlings and saplings. Economic analysis showed the viability of crab culture in mangrove pens using a combination of fish biomass and pellets to reduce the requirement for (low-value) fish, which is a food item of poor coastal communities.
Seasonal abundance, distribution and recruitment of mud crabs (Scylla spp.) in replanted mangroves ME Walton, L Le Vay, JH Lebata, J Binas & JH Primavera -
Estuarine, Coastal and Shelf Science, 2006 - ElsevierThe abundance and distribution of mud crabs were studied in a replanted mangrove forest in Buswang, Aklan, Philippines. Two fishing gears, lift nets and bamboo traps, were used to monitor relative abundance of Scylla spp. populations from March 2002 to December 2003 inside the mangrove forest. A third gear, a stakenet set across a creek, was used to monitor crabs migrating out of the mangroves during the ebb tide. Scylla olivacea formed 99.3% and 70.3% of the catch in the mangrove and the stakenet, respectively. The percentage of Scylla tranquebarica increased from <1% in the mangrove catches to 29% in the stakenet. Scylla serrata was present at very low levels in both catches. The lack of modal progression in the size–frequency plots and the year-round catch rate of gravid females suggested that recruitment was constant throughout the year. Even though relative abundance decreased over the study period indicating that the stock is being over-exploited, mud crab production is more than equivalent to that of most natural mangroves.