Two 8-week feeding trials were conducted with juvenile Pacific white shrimp, Litopenaeus vannamei (Boone) to compare the growth and performance of animals fed a series of experimental and commercial pelleted shrimp and fish feeds and dietary feeding regimes within an indoor running-water culture system and an outdoor zero-water-exchange culture system. The best overall shrimp growth performance was observed for animals fed the experimental shrimp diet and all-day feeding regime under outdoor zero-water-exchange culture conditions. Final body weight and average weekly growth rate under these conditions were 2.8 and 3.4 times greater, respectively, than animals of similar size fed with the same diet under indoor running-water culture conditions. Although direct comparison between indoor and outdoor culture systems is difficult because of the lower indoor water temperatures, and consequently lower mean daily feed intake of animals, it is believed that the higher growth and feed performance of animals reared under outdoor 'green-water' culture conditions was primarily due to their ability to obtain additional nutrients from food organisms endogenously produced within the zero-waterexchange culture system. The most promising features of zerowater-exchange culture systems are that they offer increased biosecurity, reduced feed costs and water use for the farmer, and by doing so provide a potential avenue of moving the shrimp culture industry along a path of greater sustainability and environmental compatibility. KEY WORDS

Simple, rapid and reliable methods are required to monitor the microbial community change in aquatic pond for better animal performance. Four floc (suspended organic matter) samples were collected from outdoor raceways and tanks used for culturing Pacific white shrimp Litopenaeus vannamei. Twenty‐two chlorophyll (Chl) and carotenoid pigments were separated, identified and quantified using high‐performance liquid chromatography–ultraviolet/Vis‐mass spectrometry in the freeze‐dried floc samples. Algal community composition (diatoms, chlorophytes, cyanobacteria, dinoflagellates and cryptophytes) was determined by measuring concentrations of the respective taxonomic biomarkers (carotenoid fucoxanthin, lutein, zeaxanthin, peridinin and alloxanthin) as independent variables and Chl a as the dependent variable using a multiple regression model. This analysis found that the phytoplankton community of the floc samples from two groups of shrimp tanks (32 g L−1‐salinity) were diatom‐dominated (81.7% and 84.4%); and two floc samples from shrimp raceways (5 and 18 g L−1‐salinity) were chlorophyte‐dominated (75.4% and 82.3%). Assessment of total algal and bacterial biomass by quantification of Chl a and muramic acid, respectively, indicated that the 18 g L−1‐salinity raceway sample was bacteria‐dominated, whereas the other three floc samples were algae‐dominated. Sample protein quality was evaluated by its essential amino acid (AA) score and index. Arginine and lysine were found to be the two most limiting AAs for all floc samples.

A growth trial was conducted to determine the effects of inclusion of whole shrimp floc or floc fractions to a control diet on growth and survival of shrimp (Litopenaeus vannamei). The floc sample was collected from marine shrimp culture tanks and partially fractionated by extraction with water, acetone and hexane. A series of diets was manufactured by inclusion of whole floc (intact or ground), each of the fractions or their combination to a control diet. These diets were fed to shrimp (approximately 1.0 g) in an indoor laboratory under flowthrough conditions for 8 weeks. It was found that addition of whole floc (200 g kg )1 ) or floc fractions (24-200 g kg )1 ) to the control diet improved (P < 0.05) shrimp growth rate without affecting (P > 0.05) shrimp survival (>81.3%). Although inclusion of whole floc reduced the crude protein and crude fat contents and gross energy of the control diet, shrimp fed the whole floc-supplemented diets obtained the highest (P < 0.05) growth rates (1.01 and 1.03 g week )1 ) among the shrimp fed the 11 tested diets including two control (0.81 and 0.85 g week )1 ), two commercial (0.45 and 0.71 g week )1 ) and five floc-fraction-added (0.91-1.00 g week )1 ) diets. Many bioactive compounds in the floc that possibly affected shrimp growth were also analysed and quantified.KEY WORDS premix LV99.1 -to supply the following elements (mg kg )1 diet): zinc (as sulphate) 72 mg, iron (as sulphate) 36 mg, manganese (as sulphate) 12 mg, copper (as sulphate) 24 mg, cobalt (as chloride) 0.6 mg, iodine (as iodate) 1.2 mg, chromium (trivalent, as chloride) 0.8 mg, selenium (as selenate) 0.2 mg and molybdenum (as molybdate) 0.2 mg. 9 Oceanic Institute vitamin premix LV99.1 -to supply the following vitamins (mg or IU kg )1 diet): thiamine 40 mg, riboflavin 60 mg, pyridoxine 60 mg, pantothenic acid 180 mg, niacin 80 mg, biotin 0.6 mg, inositol 400 mg, folic acid 6 mg, cyanocobalamine 0.10 mg, vitamin A 6000 IU, vitamin D3 2000 IU, vitamin E 250 mg, vitamin K 40 mg and astaxanthin 60 mg (premix prepared for Oceanic

Despite the shrimp ability to obtain additional nutrients from food organisms endogenously produced within the Ôgreen waterÕ system has been suggested as one of the causes for the better performance of Pacific white shrimp reared in Ôgreen waterÕ in comparison with Ôclear waterÕ, the nutritional components responsible for these effects have yet to be determined. The present study aims to understand the importance of natural food organisms in zero-water exchange systems as source of essential fatty acids for the Pacific white shrimp Litopenaeus vannamei. Five treatments were tested: two conducted in mesocosms systems with shrimp-fed diets containing either fish oil (FO) or olive oil, and another three conducted in clear water with shrimp-fed diets containing either olive oil, a docosahexaenoic acid (DHA)-rich oil or an arachidonic acid (ARA)-rich oil. The presence of higher levels of fatty acids 16:1n-7, 17:1, 20:4n-6, 20:3n-3 and 22:5n-6, characteristic of floc lipids, in shrimp reared in mesocosms denoted their assimilation from the floc. Substitution of FO by olive oil in diets for shrimp reared in mesocosms did not affect growth or survival. Survival and growth of shrimp reared in mesocosms was better than those reared in clear water and fed an olive oil diet, whereas DHA or ARA enrichment of non-fish oil (NFO) diet improved survival of shrimp reared in clear water. Higher survival rate, triglyceride and DHA content in whole body and eyes of shrimp fed a DHA-rich diet suggests that under these conditions, in clear water, it is necessary to include at least 4.8 g kg )1 DHA in diet dry weight. ARA enrichment seemed to negatively affect growth. The nutritional contribution of the floc to shrimp in mesocosm culture reduces or eliminates the need for a dietary source of FO and illustrates the importance of DHA and ARA to enhance shrimp survival in clear water conditions. KEY WORDS

Recent efforts have been made to culture marine shrimp in systems operating under low or zero‐water exchange and with decreased water salinity. The aim of this study was to investigate the impact of various salinity levels on qualitative and quantitative characteristics of the natural community and, more particularly, ciliated protozoa, and compare this information with shrimp growth and survival. Tanks with 9‰ salinity were characterized by a higher pH, but also by a significantly higher concentration of chlorophyll a (Chl a) per weight of suspended matter (1.93 ± 0.72 µg Chl a/mg TSS) than tanks with 18‰ (1.29 ± 0.68 µg Chl a/mg TSS) or 36‰ (1.37 ± 0.61 µg Chl a/mg TSS) salinity. Concentrations of ciliates (max 6000 cells mL−1) showed considerable fluctuations over the sampling period, reflecting the impact of water salinity, dynamic interactions between ciliates and their diverse roles within the shrimp production system. There was no significant difference between survival rates of shrimp reared at 9‰, 18‰ or 36‰, but decreasing salinity from 36‰ to 9‰ led to a significant decrease in final shrimp body weight (from 13.40 ± 0.26 g to 10.23 ± 2.72 g). Future work should address the potential of ciliates as an indicator of aquaculture water quality, as is currently being done in the wastewater industry, and the contribution of ciliates as food sources.