Effect of density on population development in the Amazon River prawn Macrobrachium amazonicum

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ontogenetic Variation in Ammonia Excretion during the Early Life Stages of the Amazon River Prawn, Macrobrachium amazonicum

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Sensory aspects of liquid smoking of giant river prawn: comparison with traditional smoking

P>The purpose of this paper is to investigate the impact of liquid smoke on the sensory characteristics of giant river prawn (Macrobrachium rosenbergii). The sensorial profile was plotted using quantitative descriptive analysis and assessment of the acceptability of samples of beheaded and peeled and only beheaded freshwater prawns smoked using the traditional method or liquid smoke (LS). The prawns subjected to LS were characterised by their aroma, artificial flavour and bitter flavour. The beheaded, peeled prawns were found to be more acceptable, confirming that the presence of the shell is a limiting factor in the acceptability of smoked prawns.

Histoarchitectural Features of the Hepatopancreas of the Amazon River Prawn Macrobrachium amazonicum

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of polyunsaturated fatty acids on the fecundity of the Amazon river prawn Macrobrachium amazonicum (Heller, 1862)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Population structure and reproductive period of whitebelly prawn Nematopalaemon schmitti (Holthuis 1950) (Decapoda: Caridea: Palaemonidae) on the southeastern coast of Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Feeding habit of the Amazon river prawn Macrobrachium amazonicum larvae

To investigate the feeding habit of Macrobrachium amazonicum, three experiments were carried out assessing the stage at which larvae start exogenous feeding, the acceptance of inert food by different larval stages and the ratio between live and inert diet ingested by larvae at each larval stage. In the first experiment, newly hatched larvae were kept in 500-mL beakers and fed from stages I, II or III onward. Larval survival was not affected by the larval stage at which exogenous feeding started, but mean weight gain was lower when food was offered from stage III onward. In the second experiment, 60 larvae from each stage (I to IX) were fasted for 2 h and then fed on inert diet in excess. Only larvae from stage IV onward accepted this inert diet. In the last experiment, newly hatched larvae were stocked in a larviculture tank and fed daily on both Artemia nauplii and inert diet. After 15 min, food content in the digestive tract of individual larvae was analyzed under stereomicroscopy. Larvae in stage I did not feed, while live food was accepted from stage II onward and inert food from stage III onward. Larvae in stages IV, V and VI accepted both foods with no preference, while inert food was predominant in stages VII to IX In conclusion, to feed M amazonicum larvae on Artemia before stage II or on inert diet before stage IV is unnecessary. It increases production costs and may impair water quality. From stages IV to VI, feeding on Artemia and inert diet is probably necessary, while inert diet should be the main food item from stage VII onward. This schedule may optimize feeding management and production costs. (c) 2007 Elsevier B.V. All lights reserved.

Comparison of artificial and natural, new and reused, brackish water for the larviculture of the freshwater prawn Macrobrachium rosenbergii in a recirculating system

Differences in culture duration, metamorphosis rate and the productivity in hatchery culture of M. rosenbergii using a closed system with natural and artificial brackish water were evaluated. Reuse of brackish water in more than one hatchery cycle was also evaluated. Natural and artificial brackish water constituted the two tested treatments, which were distributed in four independent recirculating systems (tank and respective biofilter). Four batches of cultures were conducted and the 2nd and 4th reused the water from the 1st and 3rd, respectively. Mean duration of the hatchery period was 28 d in natural brackish water and 31 d in artificial brackish water. The metamorphosis rate and the average productivity for the natural brackish water treatment were 74% and 60 postlarvae/ L. respectively, and values obtained with artificial brackish water were 55% and 44 postlarvae/L. The successful hatchery culture of M. rosenbergii in this specific artificial brackish water suggests its potential use in enterprises located far from the coast. Brackish water can be used in two consecutive cultures without a negative effect on productivity.

Production of Nile tilapia Oreochromis niloticus and freshwater prawn Macrobrachium rosenbergii stocked at different densities in polyculture systems in Brazil

The effect of stocking prawns Macrobrachium rosenbergii at increasing densities in ponds with Nile tilapia Oreochromis niloticus reared at low density was evaluated. Twelve 0.01-ha earthen ponds were stocked with 1 tilapia/m2 and 0, 2, 4, or 6 post-larvae prawn/m2. Three replicates were randomly assigned to each prawn density. Postlarval prawns were stocked a week prior to tilapia juveniles and both were harvested 175 d after the beginning of the experiment. Tilapia final average weight, survival, production, and food conversion rates did not differ significantly among treatments (P > 0.05); the averages were 531 g. 67%, 3,673 kg/ha, and 1.91, respectively. Prawn survival rates did not differ for the three stocking densities (mean 90%). However, final weight and production were significantly different (P < 0.05) as follows: 34.0, 23.0, and 14.7 g and 639, 909, and 818 kg/ha, respectively for 2, 4, and 6 prawns/m2 densities. Stocking densities up to 6 prawn/m2 did not affect tilapia production and required neither additional feeding nor significant changes in management. The polyculture system allowed an increase in total production with the same amount of supplied feed, thus improving the system sustainability.

Effects of nitrate concentration on larval development of the giant river prawn, Macrobrachium rosenbergii

The effect of nitrate concentration on giant river prawn, Macrobrachium rosenbergii, larvae was investigated. Survival rate, weight gain, and larval development were evaluated for different concentrations of nitrate in three experiments. The experiments were divided i n to two phases. In the first phase, larvae from stages I through VIII were analysed, while in the second phase larvae from stage VIII through post-larvae metamorphosis were analysed. Oxygen consumption was also determined for zoea I, II, and VIII exposed to 0, 700, and 1,000 mg/L of nitrate-N. No effect was observed for concentrations up to 180 mg/L NO3-N (experiments I and II), and nitrate levels as 1,000 mg/L NO3-N did not affect survival in the first phase of the third experiment. On the other hand, larval stage index (LSI) and weight gain decreased as nitrate-N concentration increased from 0 to 1,000 mg/L. In the second phase, survival and metamorphosis rate decreased as nitrate concentration increased, according to a linear model. The effect of nitrate levels on weight gain followed a curvilinear pattern. Larval respiration decreased in the water where nitrate was added, but only during stage II. The results demonstrated that nitrate presents extremely low toxicity for giant river prawn larvae, and data were related to the levels of nitrate that usually occur in larviculture systems also discussed. Therefore, nitrate is not a limiting factor for giant river prawn larviculture. © 2003 by The Haworth Press, Inc. All rights reserved.

Larval development of the giant river prawn Macrobrachium rosenbergii at different ammonia concentrations and pH values

The effect of ammonia and pH levels on giant river prawn Macrobrachium rosenbergii larvae were evaluated to provide science-based information on safe levels of ammonia and pH for larviculture. Survival rate, developmental stage, and larval weight gain were determined for larvae kept in water with total ammonia (NH4-N) concentrations of 0, 1, 2, 4, and 8 mg\L and pH 7, 8, and 9. The trials were conducted in two phases: phase 1, larvae from stages I through VIII and phase 2, larvae from stage VIII until metamorphose. Oxygen consumption was determined for larvae in stages I and VIII at total ammonia concentrations of 0, 4, and 8 mg/L and pH 8. Survival rate up to stage VIII varied from 86 to 98% and did not differ for total ammonia concentrations in pH 7 and 8 and for 0 mg/L NH4-N in pH 9. Survival rate was significantly lower (0-20%) for total ammonia concentrations from 1 to 8 mg/L (0.43-3.41 mg/L of unionized ammonia) in pH 9. Larval stage indexes (7.9-8.0 range) and weight gain (1.572-2.931 mg range) of larvae at the end of phase 1 of the experiment did not differ for the different ammonia concentration solutions, but were significantly lower in pH 9. In phase 2, no parameter differed among treatments for pH 7 and 8; however there was total mortality at pH 9 until 96h. Respiration rates diminished when larvae were exposed to total ammonia concentrations of 4 and 8 mg/L (0.28 and 0.55 mg/L of unionized ammonia), but development remained unaltered. Therefore, M. rosenbergii larvae tolerate high levels of total ammonia, while toxicity depends primarily on unionized ammonia concentrations. In addition, alkaline pH (9) acted directly on the larvae, curbing development and causing severe mortality. Larval tolerance to high ammonia and pH levels decreases for the last zoeal stages. © Copyright by the World Aquaculture Society 2005.

Shelf-life of tail meat of the giant river prawn, Macrobrachium rosenbergii, stored on ice

The objective of this study was to evaluate the shelf-life of peeled giant river prawn Macrobrachium rosenbergii stored directly in contact with ice (DCI), and without direct contact with ice (WCI). The prawns from DCI treatment showed an intense leaching of non-protein nitrogen (NPN) and total volatile bases nitrogen (TVB-N), thus suggesting that NPN or TVB-N should not be used as freshness indicators of peeled tails stored directly in contact with ice. Loss of flavor and a quick texture tactile decrease with time occurred in both treatments. The shelf-life of peeled tails prepared from M. rosenbergii was 7 days for DCI and 10 days WCI. © 2006 by The Haworth Press, Inc. All rights reserved.

Reproductive cycle, ovarian development, and vertebrate-type steroids profile in the freshwater prawn Macrobrachium rosenbergii

This study is intended to characterize the ovarian development and hemolymph vertebrate-type steroids concentration during the reproductive cycle of the freshwater prawn, Macrobrachium rosenbergii. A five-stage classification based on the external observation of the ovary's size and color as seen through the tegument was used. The results showed the existence of a direct correspondence between the ovarian stages and the gonadosomatic index, the oöcyte diameter, and the characteristics of ovarian histology. In each stage total bleeding of the prawns was conducted and the hemolymph concentrations of 17β-estradiol (E 2), testosterone (T) and 17α-hydroxyprogesterone (17-OHP; conjugated and unconjugated) were determined by solid-phase radioimmunoassay (RIA). High levels of unconjugated 17-OHP, relatively constant concentrations of unconjugated T, and null concentration of unconjugated E 2 were found throughout the five stages considered. Nonetheless, low levels of E 2 were determined in all stages, in conjugated (glucoronide) form. The highest levels were obtained in stage II and III (18.14 ± 14.52 pg/ml hemolymph) and progressively declined in the other stages (7.53 ± 6.76 pg/ml hemolymph). These results point out the possible involvement of vertebrate-type steroids in the endocrine regulation of the Macrobrachium rosenbergii's ovarian cycle. To our knowledge this is the first study concerning the vertebrate-like steroid levels throughout the ovarian cycle and is a step needed to characterize the hemolymph profile of these steroids in order to elucidate the possible role in the regulation of the reproductive crustacean cycle.