The objective of this experiment was to evaluate soy-protein-concentrate (SPC, 65% protein) as a replacement ingredient for ®shmeal (FM, 65% protein) in shrimp diets. Shrimps (Penaeus monodon, PL-15) were raised in the laboratory to 1.5 g body weight and were then transferred into 120-L aquaria with water temperature maintained at 28 T 2°C. Five isonitrogenous and isocaloric diets (protein 36%, ME 15.7 kJ g ±1 ) were prepared using SPC at inclusion levels of 0, 8.75, 17.50, 26.25 and 35% by replacing 0, 25, 50, 75 and 100% of the FM from the diet, respectively. All diets contained 12% soybean meal. The diets were randomly assigned to 45 aquaria (n = 9), each containing 30 shrimps. Shrimps were fed to satiation four times a day for an 8-week period and were exposed to alternating 12 h light and dark periods. Aggregate body weight for each aquarium was recorded every 2 weeks, when shrimps were also counted.The feed intake by shrimps was not different at 0, 25 or 50% FM substitution levels, but was signi®cantly decreased at 75 and 100% substitution levels. The body weight gains of shrimp fed diets with 0, 25 or 50% FM substitution were signi®cantly better than those fed diets with 75 or 100% FM substitution. A 100% substitution of FM from the diet had a severe negative effect on the body weight gain. With increasing substitution of FM with SPC, the feed ef®ciency ratio, protein ef®ciency ratio, and protein and fat gain in the shrimp followed the same general pattern as described for body weight. Mortality was not signi®cantly different among the dietary treatments. These data indicate that a 17.5% inclusion of SPC in the diet of P. monodon can support normal growth of the shrimp with the potential for substituting FM.

No abstract

Fish assemblage patterns were studied in the lower river reach of the Uthokawiphatprasit anti-salt dam, 6 km upstream from the Pak Panang River mouth, Southern Thailand, where the dam was opened occasionally depending on the upstream water level. Matrix data of the presence-absence of 71 fish species in 102 surveys was used in the analysis by applying a self-organizing map (SOM) model. The trained SOM (lattice 8 Â 7) showed that after 6 years of operation, five assemblage patterns were distinguished. These patterns described the probability of the occurrence of fish in each fish environmental guild, which according to changes in flow and water geomorphology. Clusters Ia and Ib were mostly the surveys in upstream stations and occupied by fish in potamonic guilds, whereas the fish in the estuarine guild and marine guilds showed a high probability of occurring in clusters IIa, IIb and IIc, which belonged to the surveys in downstream stations. The surveys of the stations near the dam (i.e. stations 5 and 6) during the opening phase were contained in cluster IIb. The Kruskal-Wallis test showed that there was no statistical difference in the probability of occurrence among assemblages of the diadromous, catadromous and semi-anadromous fishes but not the amphidromous fishes, which had a low probability of occurrence in clusters Ia and Ib. The fish assemblages were arrayed along a longitudinal gradient, where salinity and pH were the most important controlling variables and explained 94.0% of the total inertia.

Following the construction of an anti-salt intrusion dam in Pak Panang River, Thailand, changes in the environmental conditions and fish assemblages were monitored both in the estuary and in the river. The present study was conducted during two different phases: when the sluices were open; and when they were closed. Salinity in the estuary declined (P < 0.001), but increased in the river during the open phase (P = 0.002). In the river, the pH increased (P < 0.001) during the closed phase, but was relatively constant in the estuary. No differences were found for water temperatures, chlorophyll a and abundance of phytoplankton. During the closed phase, the abundance of zooplankton was higher in the estuary, but the abundance of benthos in the river declined. Ninety-four fish species were collected. Species richness and the diversity index did not differ in the estuary, but were significantly different in the river; abundance was higher during the open phase. Fish moved between the two systems during the open phase and changes in fish assemblages correlated with salinity gradients and food sources. Sluice regulation to allow fish to move between the river and the estuary is recommended.

Penaeus monodon is one of the most economically important shrimp species in Thailand. However, little information is available about the functional genomics related to its growth performance. In this study, Illumina paired-end sequencing was used to analyze transcriptomes related to growth performance in P. monodon muscle. A total of 38.4 million reads were generated. The pooled reads, from 10 libraries, were de novo assembled into 113,991 genes, with an average length of 337 bp. Gene expression was analyzed with the edgeR program, which revealed 705 differentially expressed contigs (p < 0.05) in fast-growth shrimp compared to slow-growth shrimp. The results show the 234 up-regulated contigs in fast-growth shrimp are mostly underlined genes involving the metabolic pathway. Quantitative real-time polymerase chain reaction (qRT-PCR) revealed seven genes involved in the cell cycle that were expressed more in fast-growth shrimp (p < 0.05) than in slow-growth shrimp, and moderately to strongly correlated with shrimp body weight. These genes may be good candidates for growth performance improvement in P. monodon.