Suriyan Tunkijjanukij

Spatial and temporal genetic variation of green mussel, Perna viridis in the Gulf of Thailand and implication for aquaculture.

The culture of green mussel (Perna viridis) in the Gulf of Thailand depends on natural spat which are believed to come from spawning grounds adjacent to major river mouths. In the present paper, genetic diversity of spatial and temporal populations of green mussel in the Gulf of Thailand was investigated using five microsatellite loci. The results showed moderate genetic variation of all 11 populations (averaged number of alleles per locus, A = 10.4–12.2; effective number of alleles per locus, Ae = 5.36–6.59; mean allelic richness, Ar = 10.23–12.06; observed heterozygosity, Ho = 0.52–0.63, and expected heterozygosity, He = 0.66–0.73) without significant differences among populations. No sign of bottleneck or genetic disequilibrium was observed. Genetic differentiation among spatial populations was low (FST = 0.0046, CI0.95 = 0.0020–0.0083 for the samples collected in January, 2007, and FST = 0.0088, CI0.95 = 0.0010–0.0162 for the samples collected in July, 2007) while temporal variation was significant as revealed by the analysis of molecular variance. Multidimensional scaling separated temporal population groups with minor exception. The assignment test revealed that most of the recruits were from other populations.

Bottom soil characteristics, survival and production of shrimp in low-salinity, inland ponds in Alabama and Florida (USA)

PurposeEffects of pond bottom soil characteristics on survival and production of shrimp were investigated for low-salinity shrimp farms: Greene Prairie Aquafarm (GPA) near Forkland, Alabama and Gulf American Shrimp (GAS) near Howard’s Creek Landing, Florida.Materials and methodsFarm histories, management methods, and records of stocking rates, survival rates, and production were provided by farm owners. Pond soil samples were collected in 2012 and analyzed for particle size, pH, carbonate, organic carbon, total nitrogen, total sulfur, extractable phosphorus, calcium, magnesium, potassium, sodium, aluminum, iron, manganese, zinc, copper, and boron.Results and discussionSoils at both farms exhibited a wide range in pH, clay content, and concentrations of chemical constituents. Correlations (P > 0.05) were not found between soil variables and shrimp survival and production. Some ponds typically had poor survival and production, and at GPA, these ponds were higher in clay (P < 0.05) than other ponds. There were no differences (P > 0.05) in other soil variables between ponds with low survival and production and other ponds at either farm. Annual draining and dry-out of ponds at GAS did not result in lower organic C concentration in soil than at GPA where ponds were not drained.ConclusionsSoil of high clay content was the only soil variable associated with frequent, low shrimp survival and production in some ponds at GPA. Bottom soil characteristics were not related to low survival and production typically observed in some ponds at GAS. Draining and dry-out of ponds between production cycles is not necessary for preventing high soil organic C concentrations.