Effect of salinity on survival of Metapenaeus anchistus juveniles and subadults
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Survival of Metapenaeus anchistus (De Man) juveniles and subadults at 5, 15, 25, 35 (control) and 45 ppt salinity levels was determined and compared. Salinity levels lower than 35 ppt level were prepared by diluting pure seawater with tap water (OPPT) while 45 ppt level was prepared by diluting 85 ppt water with tap water. Survival was observed at 0.5, 1, 2, 3, 6, 12, 18, 24 h after stocking and every 12 hours thereafter until 96 h. Shrimp survival was highest at 35 ppt (P<0.01); differences among treatments were first observed at 2 h after exposure with some shrimps dying at 5 ppt. At the end of the experiment, survival was highest at 35 ppt (100%), followed by 25 and 45 ppt (90 and 80%, respectively), 15 ppt (50%) and 5 ppt (0%).
CitationLebata, M. J. H. L., & Primavera, J. (1997). Effect of salinity on survival of Metapenaeus anchistus juveniles and subadults.
PublisherUniversity of the Philippines in the Visayas
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ArticleJRH Maquirang, RD Caturao, JH Maquirang & FL Pedroso -
IAMURE International Journal of Ecology and Conservation, 2013 - IAMURE Multidisciplinary ResearchThe study was conducted to determine the optimum salinity levels (24 ppt, 28 ppt, 32 ppt, 36 ppt and 40 ppt) for the survival and settlement rates of H. asinina in a complete randomized design with three replicates each. The experimental animals were reared in 15 glass aquaria for the first run and in plexiglass for the second run. Feeding of Navicula spp. was done once a day. Temperature and dissolved oxygen were monitored throughout the experiment. Data were analyzed using One-Way ANOVA to determine significant difference among treatments at 0.05 level of significance using Social Package for Social Science. Result of the first run showed that 32 ppt had the highest mean survival (1.50%) and mean settlement rate (1.84%). Similar result was also observed in 32 ppt with highest mean survival (9.72%) and mean settlement rate (16.42%). Significant difference existed among treatments during the second run of the experiment. Results showed that 28 ppt and 32 ppt were the optimum salinity levels for survival and settlement rate of H. asinina. Further study should be conducted to determine the tolerance and settlement rates of H. asinina larvae to lower salinities until it reaches juvenile stage with first respiratory pore appearing.
Growth response of Nile tilapia fry to salinity stress in the presence of an ‘internal reference’ fish Growth of three strains of Oreochromis niloticus L. fry exposed to salinity stress in the presence of an internal reference fish were compared. The Central Luzon State University (CLSU) strain was obtained from the Freshwater Aquaculture Center, CLSU, Philippines. The ISRAEL strain was acquired from the Philippine government's Bureau of Fisheries and Aquatic Resources National Freshwater Fisheries Technology Center (BFAR-NFFTC), Munoz, Nueva Ecija. The National Inland Fisheries Institute (NIFI) strain was obtained from the NIFI, Bangkok, Thailand. Eight to nine full-sib families (replicates) per strain were split into two groups. One group was grown in freshwater for 2 weeks, acclimated to 32 ppt and reared for 2 weeks and finally grown in freshwater for another 2 weeks. Another group was contemporaneously grown in freshwater polyethylene tanks for 6 weeks. Each replicate family included a size-matched internal reference population of red tilapia strain. Two-way analysis of variance (anova) revealed no significant strain differences (P=0.081; r2=0.106). However, analysis of covariance with the internal reference strain used as a covariate showed significant (P=0.049; r2=0.638) strain effects on specific growth (based on standard length measurements). The ISRAEL strain showed consistently better growth rate in both saline and freshwater environments than the NIFI and CLSU strains. We estimated the statistical power of the two-way anova (ϕ=√(k′−1)(factor MS−s2)/(k′s>2); Zar 1984) to be ∼0.30. There was a 70% probability of a Type II error and no true difference in the growth of the three strains was detected. The use of internal reference strain as a covariate improved the r2 from 0.106 to 0.638 and increased the efficiency of the test in detecting a true difference. Other strain comparison studies in our laboratory at the Southeast Asian Fisheries Development Center Aquaculture Department showed that the ISRAEL strain shows better growth than the NIFI and CLSU strains in a crowding stress tolerance experiment, when fed only with rice bran and under restrictive feeding regimes.
Enrichment of live food with essential fatty acids and vitamin C: effects on milkfish (Chanos chanos) larval performance The effects of essential fatty acids (EFA) and vitamin C-enriched live food on growth, survival, resistance to salinity stress and incidence of deformity in milkfish larvae reared in tanks were investigated. Larvae were either fed rotifers cultured on Chlorella sp. and newly hatched Artemia nauplii (control), highly unsaturated fatty acid (HUFA)-enriched rotifers and Artemia nauplii or HUFA+vitamin C-enriched rotifers and Artemia nauplii. Milkfish growth in outdoor nursery ponds was also assessed to compare with growth in indoor tanks. Milkfish fed rotifers/Artemia enriched with HUFA (32–48 mg dry weight, DW) or HUFA+vitamin C (33–45 mg DW) exhibited significantly (P<0.05) higher growth than those given unenriched live food (24–27 mg DW) after 40 days of culture. Growth of milkfish in nursery ponds (albeit lower in stocking density) showed similar trends as those reared in tanks. When subjected to salinity stress (Day 25), mortality of the HUFA+vitamin C-treated fish and HUFA-treated fish were significantly lower (P<0.05) than the control fish. Survival of 26-day old milkfish, however, did not differ significantly (P>0.05) among the treatment groups. Forty-day-old milkfish fed HUFA+vitamin C-enriched live food had significantly lower (P<0.05) incidence of opercular deformity (mainly cleft branchiostegal membrane) (8.4–14.7%) compared with those given HUFA-enriched (15.8–23.5%) or unenriched (27.3–33.5%) live food. Results demonstrated the effect of HUFA enrichment in enhancing milkfish larval growth and resistance to salinity stress but not overall survival. Moreover, HUFA and ascorbate supplementation decreased but did not totally eliminate incidence of opercular deformity in milkfish larvae.