In 2003, seeds of Macrobrachium rosenbergii were stocked at 2, 4, and 6 postlarvae/m2 as well as 1, 2 and 3 juveniles/m2 with two culture systems, the integrated and rotational prawn - rice systems. Prawns were fed with pellets twice a day. Water levels in rice plots were arranged at the same levels for both systems. The dissolved oxygen concentrations in the integrated system were lower than in the rotational system. The growth of prawns decreased at higher stocking densities. Prawns in the rotational system grew faster than those in integrated system. The yields ranged from 286 ± 32 to 516 ± 51 and 412 ± 17 to 584 ± 37 kg/ha in the integrated and rotational system at stocking PL, respectively. The yields of prawns ranged from 251 ± 16 to 430 ± 54 and 297 ± 24 to 486 ± 38 kg/ha in integrated and rotational prawn - rice systems stocking juveniles, respectively. However, at higher density, the investment cost significantly increased (P < 0.05), while profit significantly decreased (P < 0.05). At low density, cost benefit ratio and profit were the highest (P < 0.05). Finally, the integrated rice - prawn system gives lower profits than the rotational system. In 2004, an experiment on the effects of stocking densities (1, 2, 3 and 4 PL/m2) and feeding types, pellets only (P) and pellets + snail meat (PS), on the production and economic aspects of rotational prawn culture in the rice fields were carried out in the same culture facilities. Water levels were 0.3 - 0.6 m in rice-grown areas. Water temperatures were higher than the suitable range for prawns at noon in the hot months. After 7 months, survival rates of prawns were 28.0 - 50.3 %. Final mean weights were 32.0 - 39.8 g/prawn. Yields ranged from 194 ± 82 to 373 ± 32 kg/ha. There was no significant difference between the two types of feeding on production parameters (P > 0.05). The total cost significantly increased at higher densities (P < 0.05) but it was not different between feed types (P > 0.05). Net profit and cost benefit ratio of treatment PS were significantly higher than in treatment P. In the present study, yield (394 ± 22 kg/ha) and cost benefit ratio (1.57 ± 0.07) in treatment PS at 3 PL/m² were significantly the highest (P < 0.05). The effects of stocking densities of postlarvae (0.5, 1 and 2 PL/m2) on the production and economics of prawn culture in the integrated rice - prawn system were studied to affirm the efficiency of this model with low investment. The high temperature in the dry season and low dissolved oxygen after rice harvesting caused small final mean weights, low survival rates and low yields. However, low investment in this system led to good cost benefit ratio. The on farm trials of rotational rice - prawn farming in the semi-deep water area were monitored with the farmers in six rice fields (0.7 - 1.0 ha). Two treatments of feed types (pellets and pellets + snail meat) were applied at stocking 4 PL/m2. Prawns in two treatments of densities (4 and 5 PL/m2) were fed on a combination of pellets and snail meat. By cull harvesting during the culture period, final mean weights of prawn were improved and larger than 50 g/prawn in all treatments. The prawn yield of treatment 5 PL/m2 was highest (630 ± 22 kg/ha). Net profits in the treatment using a combination of pellets and snail meat were 861 ± 193 US$/ha to 1,019 ± 25 US$/ha for the prawn crop and 1,393 ± 71 US$/ha to 1,576 ± 180 US$/ha for the whole system (prawn crop + dry rice crop). The integrated two rice crop and one prawn crop system with low investment costs can be applied by poor farmers, while the rotational a rice crop and one prawn crop system with higher operating costs can be practiced by moderately well off and rich farmers. Due to a higher economic return than monoculture of rice or rice - fish systems, rice - freshwater prawn system is spreading very rapidly in the Mekong Delta of Vietnam. En 2003, de jeunes Macrobrachium rosenbergii furent stockés à 2, 4 et 6 postlarves/m² ainsi qu’à 1, 2 et 3 juvéniles/m² dans deux systèmes de culture: riz et crevettes produits soit en même temps (intégration) soit successivement (rotation). Les crevettes étaient alimentées de granulés deux fois par jour. Les niveaux d’eau dans les casiers rizicoles ont été maintenus identiques dans les 2 systèmes. Les concentrations en oxygène dissous dans le système intégré étaient plus faibles que dans le système en rotation. La croissance des crevettes a diminué aux plus fortes densités. Les crevettes dans le système en rotation ont grandi plus rapidement que dans le système intégré. Les récoltes à partir de postlarves se sont étalées de 286 ± 32 à 516 ± 51 et de 412 ± 17 à 584 ± 37 kg/ha respectivement dans le système intégré et en rotation. Les récoltes à partir de juvéniles se sont étalées de 251 ± 16 à 430 ± 54 et de 297 ± 24 à 486 ± 36 kg/ha respectivement dans le système intégré et en rotation. Cependant, à plus forte densité, les coûts d’investissement augmentent significativement (P < 0,05), tandis que le profit diminue significativement (P < 0,05). A faible densité le rapport coûtbénéfice et le profit ont été les plus élevés (P < 0,05). Finalement, le système intégré riz-crevette donne des profits plus faibles que le système en rotation. En 2004, une expérience sur les effets de différentes densités de mise en charge (1, 2, 3 et 4 PL/m²) et des types d’aliments, granulés uniquement (G) ou granulés et viande d’escargot (GE), sur la production et les aspects économiques de la culture riz-crevette en rotation ont été effectués dans les mêmes installations que précédemment. Les niveaux d’eau ont varié de 0,3 à 0,6 m dans les zones de production du riz. Les températures de l’eau ont été plus élevées que la température optimale pour la crevette du moins à midi pendant les mois les plus chauds. Après 7 mois, les taux de survie ont été de 28,0 à 50,3 %. Les poids moyens finaux étaient de 32,0 à 39,8 g/crevette. Les récoltes s’étalaient entre 194 ± 82 à 373 ±32 kg/ha. Aucune différence statistique (P < 0,05) concernant les paramètres de production n’a été enregistrée entre les deux types d’alimentation. Les coûts totaux ont augmenté significativement (P < 0,05) à plus fortes densités de mise en charge mais n’étaient pas différents selon les types d’aliments. Le profit net et le rapport coût bénéfice ont été significativement plus élevés avec les aliments combinés (GE) qu’avec les granulés seuls (G). Nos travaux démontrent que la récolte (394 ± 22 kg/ha) et le rapport coût bénéfice du traitement aliment combiné (GE) à 3 PL/:m² donne les meilleurs résultats (P < 0,05). Les effets de différentes densités de mise en charge de postlarves (0,5, 1 et 2 PL/m²) sur la production et le gain monétaire de l’élevage de crevette d’eau douce dans le système riz –crevette intégré ont été étudiés afin de confirmer l’efficacité de ce modèle basé sur un faible investissement. La température élevée en saison sèche et les faibles concentrations en oxygène dissous de l’eau après la récolte du riz induisent des poids moyens finaux faibles, de faibles taux de survie et de faibles récoltes. Cependant, le faible investissement nécessaire conduit à un bon rapport coût bénéfice. Les essais sur fermes du système riz-crevette en rotation dans les zones semi-profondes du district de Codo ont été effectués de façon participative avec les fermiers dans six champs de riz (0,7-1,0 ha). Deux types d’aliments (G et GE) ont été testés à la densité de 4 PL/m² et deux types de densité (4 et 5 PL/m²) ont été testés avec l’aliment combiné (GE). Grâce à des récoltes partielles en cours de production, les poids moyens finaux des crevettes ont été améliorés et étaient supérieurs à 50 g/crevette pour tous les traitements. La récolte de crevette à 5 PL/m² a été la plus élevée (630 ± 22 kg/ha). Les profits nets du traitement combinant les 2 types d’aliments (GE) ont varié de 861 ± 193 US$/ha à 1.019 ± 25 US$/ha pour la récolte de crevettes et de 1.393 ± 71 US$/ha à 1.576 ± 180 US$/ha pour l’ensemble du système (riz + crevette). Le système intégré de deux récoltes de riz et 1 récolte de crevette par an nécessite peu d’investissement et peut être appliquée par les fermiers les plus pauvres tandis que le système une récolte de riz et une récolte de crevette en rotation par an nécessite des investissements plus conséquents et ne peut être appliqué que par des fermiers aisés ou riches. Etant donné que le revenu économique du système riz-crevette est nettement plus élevé que la seule riziculture ou même que la rizipisciculture, ce système est en train de se développer très rapidement dans le delta du Mékong.

The giant freshwater prawn, Macrobrachium rosenbergii (De Man, 1879), is gaining popularity as a key aquaculture species; global production currently exceed 220,000 tonnes, however, industry expansion is limited by high operational costs, with the feed accounting for between 40 to 60% of these. Attention, therefore, has been devoted to increasing the inclusion of plant proteins into the formulation of aqua feeds as a consequence of the limited, unpredictable supply and increasing price of fishmeal. The concomitant introductions of anti-nutritional factors (ANFs), such as phytic acid (PA) with the plant protein fraction, however, are major impediments in the efforts toward the increased use of plant protein ingredients in aqua feeds. Phytic acid is an anti-nutrient that can curtail the development of this as PA has been reported to suppress growth impairing proper nutrient intake, diminishing the availability of minerals, and causing damage to the body tissues and organs which can result in mortality. Although the anti-nutritive effects of PA have been studied extensively in terrestrial agriculture farm species, as well as in a variety of fish species, there is almost no information regarding the effects of PA in crustaceans, including the freshwater prawn, M. rosenbergii. The aims of this present thesis were, therefore, to gain a greater understanding of dietary PA and microbial phytase and their effect on growth performance, feed utilisation, nutrient utilisation and digestibility, mineral availability and whole body proximate composition in juvenile M. rosenbergii. Specifically, the first major experiment set out to investigate the effect of including increasing amounts of PA in the diets presented to M. rosenbergii on growth. The dose-response relationships between PA and growth performance, feed utilisation, nutrient digestibility and utilisation and whole proximate composition were investigated. Four replicate groups of M. rosenbergii with a mean initial carapace length of 6.03 ± 0.30 mm and mean initial weight of 0.29 ± 0.02 g were fed graded levels of PA for 140 days. The basal diet, to which different levels of PA were added to obtain 0.26 (control), 6.48, 11.28, 16.53, 21.45 and 26.16 g PA kg-1, contained fishmeal, soy protein concentrate, wheat meal and corn starch. The results indicated that growth performance, feed utilisation and survival did not differ significantly between the groups receiving the different inclusions of PA within their diets. The apparent protein, lipid and energy utilisations responded negatively, decreasing significantly (p<0.05) with an increasing inclusion of PA, particularly within the groups of prawns fed the diet with the highest inclusions of PA, i.e. the 21.45–26.16 g PA kg-1 diets. The digestibility of protein and lipid were also reduced as the inclusion of PA increased. The whole body composition of protein (p<0.04), lipid (p<0.01) and gross energy (p<0.05) decreased significantly with an increasing supplementation of PA, while the ash content significantly increased (p<0.01), most notably in the groups of prawns receiving the highest levels of dietary PA. The second major experimental trial investigated the effect of microbial phytase on the growth of juvenile M. rosenbergii, when fed diets supplemented with various doses for a period of 80 days. The study set out to improve the growth performance, feed utilisation, nutrient digestibility and utilisation and body composition of M. rosenbergii when fed diets high in plant protein ingredients. To investigate this, four plant protein based diets, which included soybean meal, wheat gluten and wheat meal, were formulated and supplemented with microbial phytase at levels of 0, 500, 1000 and 2000 FTU kg-1 (one phytase unit per kg) and fed to sixty juvenile M. rosenbergii (mean initial carapace length of 8.51 ± 0.52 mm; mean initial weight of 0.40 ± 0.07 g) for 80 days. High levels of plant protein in the diets supplemented with 0–2000 FTU kg-1 did not result in any negative effect on growth performance, feed utilisation nor on the survival of M. rosenbergii. Noticeable moderate growth improvements in line with increasing microbial phytase supplement levels were observed and the highest growth performance was seen in the group fed 2000 FTU kg-1. Supplementation of the diets with 500–2000 FTU kg-1 were found to affect the nutrient utilisation, resulting in a significant (p<0.05) increase in the protein and lipid utilisation when compared to the prawns analysed from the control group. In addition to this latter finding, an increasing supplement of phytase in the diet also resulted in an increase in the dry matter fraction as well as improvements in the digestibility of protein and lipid. There were, however, no significant differences in moisture, protein, lipid, gross energy and the ash content of the whole body of the M. rosenbergii among the groups. This thesis, in a third major trial, explored the impact of other potential ANFs associated to PA, the binding effect of PA with mineral. The effects of graded levels of PA (i.e. 0.26–control, 6.48, 11.28, 16.53, 21.45 and 26.16 g PA kg-1) on the moult frequency and mineral availability in juvenile M. rosenbergii fed over a period of 140 days were determined. The levels of PA assessed in this feed trial had no major detrimental effects on moult frequency. Negative effects (p<0.05) of high PA levels (i.e. 21.45–26.16 g PA kg-1), however, were found on the whole body P concentration. An inverse trend was recorded for the Ca content in the whole body (p<0.005) and carapace (p<0.004) with increasing PA inclusion. These results are consistent with findings for marine shrimp species such as Marsupenaeus japonicus and Litopenaeus vannamei. The graded inclusion of PA in the experimental diets also resulted in a significant reduced (p<0.03) P content in the carapace. Significant changes (p<0.05) were observed in the carapace Zn, Cu, K and Na compositions, particularly in the prawns fed the diet containing 11.28 g PA kg-1, which suggests that the specific minerals were either selectively utilised or retained in the carapace. Accordingly, this thesis investigates the potential of adding dietary supplements of microbial phytase in order to improve mineral availability as proven in several fish species. To explore this, four experimental diets were formulated - three incorporating different levels of microbial phytase (i.e. 0 FTU kg-1, 1000 FTU kg-1 and 2000 FTU kg-1) and a fourth, a control. An aliquot of 15 g PA kg-1 was also added to each treatment. The mineral premix was omitted from the test group diets except the control diet was identical to the 0 FTU kg-1 diet but included a mineral premix and an aliquot of 8 g kg-1 monosodium phosphate which replaced an equal amount of wheat meal fraction. The trial found no significant differences in growth, feed utilisation and moult frequency with the microbial phytase level within the diet, however, survival was compromised. The proximate composition of the prawn whole body was in most cases unaffected by the level of phytase. Supplementation of the diets with microbial phytase did, however, result in significant higher (p<0.05) concentrations of minerals including: 1) Ca, Mg, K and Na in the whole body; 2) Ca and Zn in muscle tissue; and, 3) Ca and Mg in the carapace. The Zn content of the carapace, however, was negatively affected by the inclusion of microbial phytase suggesting the necessity of this mineral within the diet of M. rosenbergii. This thesis contributes to current understanding surrounding the inclusion of dietary PA and the benefits of microbial phytase within the experimental diets consumed by juvenile M. rosenbergii. The knowledge gained from this work provides a means to optimise the use of plant protein ingredients and with the potential to decrease the dependability of fishmeal without compromising M. rosenbergii production and profitability, thus ultimately promoting the sustainable expansion of M. rosenbergii aquaculture.

The discipline of historical biogeography seeks to understand the contribution of earth history to the generation of biodiversity. Traditionally, the study of historical biogeography has been approached by examining the distribution of a biota at or above the species level. While this approach has provided important insights into the relationship between biological diversity and earth history, a significant amount of information recorded below the species level (intraspecific variation), regarding the biogeographical history of a region, may be lost. The application of phylogeography - which considers information recorded below the species level - goes some way to addressing this problem. Patterns of intraspecific molecular variation in wide-ranging taxa can be useful for inferring biogeography, and can also be used to test competing biogeographical hypotheses (often based on the dispersal-vicariance debate). Moreover, it is argued here that phylogeographical studies have recently begun to unite these two disparate views, in the recognition that both dispersal and vicariance have played fundamental roles in the generation of biodiversity. Freshwater dependent taxa are ideal model organisms for the current field of research, as they reflect well the underlying biogeographical history of a given region, due to limited dispersal abilities - their requirement for freshwater restricts them. To this end, this study documented the phylogeographical history of the giant freshwater prawn (Macrobrachium rosenbergii) utilising both mitochondrial (COI & 16S) and nuclear (microsatellite) markers. Samples (n = ~1000) were obtained from across most of the natural distribution of M. rosenbergii [Southern and South East (SE) Asia, New Guinea, northern Australia]. Initial phylogenetic analyses identified two highly divergent forms of this species restricted to either side of Huxley's extension of Wallace's Line; a pattern consistent with ancient vicariance across the Makassar Strait. Subsequent analyses of molecular variation within the two major clades specifically tested a number of biogeographical hypotheses, including that: 1.) a major biogeographical transition zone between the Sundaic and Indochinese biotas, located just north of the Isthmus of Kra in SE Asia, results from Neogene marine transgressions that breached the Isthmus in two locations for prolonged periods of time; 2.) Australia's Lake Carpentaria [circa 80 000 - 8 500 before present (BP)] facilitated genetic interchange among freshwater organisms during the Late Pleistocene; 3.) sea-level fluctuations during the Pleistocene constrained evolutionary diversification of M. rosenbergii within the Indo-Australian Archipelago (IAA); and 4.) New Guinea's Fly River changed course from its current easterly outflow to flow westwards into Lake Carpentaria during the Late Pleistocene. The results support hypotheses 1-3, but not 4. The potential for phylogeography to contribute significantly to the study of historical biogeography is also discussed.

Aquaculture plays an important role in economic development and food security in many countries in the world. World aquaculture production in 2006 was 51.7 million tonnes with an estimated value of US$ 78.8 billion (FAO, 2009). World production will need to increase however by 30-40 million tonnes from its current production level by 2030 to meet growing global demand for fish. In this context, aquaculture in Vietnam has developed rapidly over the past decade and the fisheries sector ranked fourth in terms of export value in 2008 (Vietnamnet, 2008). Total fisheries production in Vietnam in 2007 was 4.149 million tonnes, of which fisheries production from catch and aquaculture were 2.064 and 2.085 million tonnes, respectively. A variety of aquatic species are cultured in Vietnam, but shrimps (mainly Black Tiger shrimp Penaeus monodon, and Pacific white shrimp Litopenaeus vannamei) and ‘tra’ or ‘basa’ catfish are the most common species used in aquaculture. The giant freshwater prawn (GFP), Macrobrachium rosenbergii, is one of the most important crustacean species in inland aquaculture in many countries across the world where this species is either native or exotic. GFP is suitable for culture in a variety of farming systems, including monoculture or polyculture in ponds, pens, and integrated or rotational rice-prawn culture models. The GFP industry worldwide relies totally on wild or unimproved stocks, a practice that threatens the long-term sustainability of GFP farming due to low productivity and vulnerability of farmed stocks to disease. The current status of GFP aquaculture highlights the need for initiation of a systematic stock improvement program for the species to improve economically important traits. Large-scale selective breeding programs have been instigated for some finfish, salmonids and GIFT tilapia for example, and some selective breeding trials have been conducted on crustacean species, namely marine penaeid shrimp and freshwater crayfish. Examples of selective breeding programs on aquatic species have demonstrated that significant genetic gains can be achieved for growth rates with gains of around 10-20% per generation. While a selective breeding program is an option for GFP stock improvement, an alternative approach to improving GFP productivity, potentially with more immediate effect and one that is less expensive, is crossbreeding which may produce heterosis or hybrid vigour in crossbred offspring. Therefore, a crossbreeding strategy was trialed in the current study as a starting point for a stock improvement program for the GFP industry in Vietnam. The current study assessed the growth performance of three GFP strains (two wild Vietnamese strains from the Dong Nai and Mekong rivers, and a single domesticated Hawaiian strain) and their reciprocal crosses in a complete 3x3 diallel cross, i.e. three purebred and six crossbred strains. The diallel cross was carried out over two consecutive generations (G1 and G2). Juveniles for the experiments were produced using single-pair matings. Juveniles from each strain combination were stocked into three replicate hapas for 15 weeks. Growth data (body weight, carapace length, standard length) from the G1 and G2 were pooled for all subsequent analyses as there was no effect of generation on growth traits. Results showed that the Hawaiian strain performed best among purebred strains, and crosses with the Dong Nai or Mekong strains as dams and the Hawaiian strain as sires grew significantly faster than did the purebred Dong Nai or Mekong strains. These results suggest potential for heterosis among some crosses. Growth data were analyzed in depth by partitioning the strain combination (cross) effect into three components: strain additive genetic effects, heterotic effects, and strain reciprocal effects. Strain additive genetic and reciprocal effects were significant sources of variation for all growth traits measured. Strain additive genetic effects were highest for the Hawaiian strain and lowest for the Mekong strain for all growth traits. Reciprocal effects influenced negatively on growth rate of crosses with the Hawaiian (H) strain as dams and the Dong Nai (D) or Mekong (M) as sires compared with their reciprocal crosses (DH and MH). Heterotic effects for all growth traits were small and not significantly different from zero (P > 0.05). These results indicate that a crossbreeding approach based on the strains evaluated here provides only limited potential for improving growth rates based simply on heterotic outcomes and that a likely more productive option would be to trial artificial selection on a diverse synthetic stock. The current study also employed genetic markers (microsatellites) to characterize levels and patterns of genetic diversity in three purebred strains of GFP that originated from the diallel cross above. All three purebred strains showed relative high levels of genetic diversity in terms of allele number and individual heterozygosity across the six marker loci screened. Levels of genetic diversity present in the three purebred strains combined into a single stock were compared with that from a combination of three wild river stocks to assess the impact of domestication on genetic diversity of a ‘synthetic’ population. Results demonstrated that there was no significant loss of genetic diversity in the three purebred strains combined compared with a reference set containing the three wild populations. Therefore, a synthetic population formed from these purebred strains successfully captured the majority of genetic variation present in the wild broodstock. This synthetic population provides a potential stock for a future selective breeding program for GFP in Vietnam. The current study was also the first attempt to identify single nucleotide polymorphisms (SNPs) in key growth genes in GFP. Two key candidate genes were targeted, actin and crustacean hyperglycemic hormone (CHH), that are potentially linked to growth performance in GFP. The study screened SNPs in GFP females only, because growth performance of GFP males is influenced strongly by social rank. The study identified four SNPs in intron 3 of the CHH gene that were significantly correlated with individual body weight at harvest, while no SNPs detected in the actin gene were associated with growth traits in GFP. This finding however, needs to be confirmed using larger sample sizes and other GFP lines. The current study has produced important basic knowledge relevant to implementation of an effective stock improvement program for GFP in Vietnam. Results indicate that a selective breeding strategy rather than a crossbreeding approach is likely to be the best strategy for improving GFP culture stocks in Vietnam. In addition, the study demonstrates that application of modern molecular genetic technologies can be efficient in developing a genetically diverse, synthetic population for stock improvement and for identifying potential markers correlated with important commercial traits in GFP. Integration of DNA techniques with traditional breeding practices can facilitate GFP stock improvement in Vietnam and accelerate the industry development when improved lines are available. Some limitations of the current study and recommendations for further work are discussed.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2018-08-24T18:39:52Z No. of bitstreams: 1 2008 - Cristiane Honorato Cunha.pdf: 767814 bytes, checksum: 805ea6db9e6a4462ae4375d06559e0fd (MD5) / Made available in DSpace on 2018-08-24T18:39:52Z (GMT). No. of bitstreams: 1 2008 - Cristiane Honorato Cunha.pdf: 767814 bytes, checksum: 805ea6db9e6a4462ae4375d06559e0fd (MD5) Previous issue date: 2008-03-25 / Macrobrachium acanthurus is the freshwater prawn species that is find in almost whole coastal rivers in Brazilian coast. This work was carried out to get information about reproductive aspects of Macrobrachium acanthurus in captivity and the influence on unilateral eyestalk ablation technique. 48 females and 24 males were captured in Sahy river at Mangaratiba/RJ and kept in adaptation for 15 days. Then, the animals carapace length and total length were measured. They were distributed into 20 liters aquariums, each of them with two males and four females. Two females in each aquarium were ablated. Abiotic factors such as pH, ammonia, nitrite and oxygen levels were checked weekly and the water temperature daily. Every day the occurrence of ovigerous females were checked in each aquarium. After three days incubating, the ovigerous females were separated until the larvae eclosion. And then, they were returned to the aquarium for a new phase of reproduction. The animals were fed with ration pellets and pieces of fish. The U test (Mann-Whitney) showed a significant difference among laying intervals between the ablated and non-ablated females. The Pearson correlation showed temperature influence on incubation period on non-ablated females, but on ablated females there was no dependency relationship. The t-test showed no significant difference on fertility, between ablated and non-ablated M. acanthurus. / Macrobrachium acanthurus ? uma esp?cie de camar?o de ?gua doce encontrado em quase todos os rios litor?neos da costa brasileira. Este trabalho foi realizado com o objetivo de obter informa??es sobre a influ?ncia da t?cnica de abla??o unilateral do ped?nculo ocular na reprodu??o de Macrobrachium acanthurus em cativeiro. Foram utilizados no experimento 48 f?meas e 24 machos, que foram coletados no Rio Sahy, Mangaratiba/RJ e foram mantidas durante 15 dias para a adapta??o. Posteriormente, os animais foram medidos em rela??o ao comprimento da carapa?a e comprimento total, distribu?dos na propor??o de dois machos para quatro f?meas em doze aqu?rios com capacidade de 20 litros. Das quatro f?meas de cada aqu?rio, duas foram abladas. Os fatores abi?ticos como o pH, am?nio, nitrito e oxig?nio dissolvido foram verificados semanalmente e a temperatura da ?gua diariamente. Todos os dias foram verificados a ocorr?ncia de exterioriza??o dos ovos em cada f?mea. As f?meas ov?geras ap?s tr?s dias de incuba??o foram individualizadas at? a eclos?o das larvas. Ap?s a eclos?o das larvas, as f?meas retornaram para o aqu?rio para uma nova fase de reprodu??o. Os animais foram alimentados com ra??o peletizada e peixe fresco. Atrav?s do teste U (Mann-Whitney) foi verificado que houve diferen?a significativa para o intervalo entre as desovas entre f?meas abladas e n?o abladas. Atrav?s da Correla??o de Pearson verificou-se que houve influ?ncia da temperatura no tempo de incuba??o nas f?meas n?o abladas, mas nas f?meas abladas n?o houve rela??o dependente. Atrav?s do teste t foi verificado que n?o houve diferen?a significativa para fertilidade entre as f?meas abladas e n?o abladas de M. acanthurus.

The freshwater prawn, Macrobrachium rosenbergii (de Man, 1879) is an important aquaculture species but one that has the disadvantage of heterogeneous individual growth (HIG) according to different morphotypes. Chemical cues, especially, pheromones, are one of the most important communication types between individual prawns, along with visual and tactile methods. Testing pheromones, whilst restricting other cues, may therefore lead to a better understanding of the influence of these communicatory compounds on the prawn reproductive process. The three principle objectives of this study were therefore: 1) To examine the effect of moult stage and morphotype on pheromone-induced sexual behaviour 2) To examine the role of pheromone / urine concentrations on sexual attraction behaviour 3) To describe the functional morphology of the antennal gland and examine its possible role in pheromone production and release. Identical bioassay tanks were designed and constructed to study the reproductive behaviour of prawns. Experiments were set up to examine responses to pheromone release by live prawns over 30 minutes and behavioural response observations were made with the aid of a Closed-Circuit Videotape System (CCVS). Results were statistically analysed using a repeated measures general linear model (GLM). Three trials were designed to test the effect of moult stage of both males and females and male morphotypes on sexual attraction behavioural responses. Twelve prawns were used for each trial and each prawn was used five times (1 no-pheromone control and 4 for experimental tests). The first trial studied the effect of female moult stages (pre-, inter and newly-moulted) on sexual attraction behaviour of blue claw (BC) male. Results of this trial showed that newly-moulted females spent significantly (p<0.05) less time approaching the BC male than the pre- and inter-moult females. The second trial studied the effect of male moult stage (pre-, inter and newly-moulted) on sexual attraction to receptive females. Results showed that the time taken by the inter-moult males was (p<0.05) less than the pre- and newly-moulted males in approaching the newly-moulted female. The third trial tested the effect of male morphotypes (small male, SM, orange claw, OC and dominant blue claw, BC) on sexual attraction behaviour towards newly-moulted females. Results showed that the BC male was significantly more attractive (p<0.05) than other morphotypes to newly-moulted females and that the OC male was the least attractive. The role of moulting stage for both male and female prawns on reproductive response behaviour was investigated. Because BC males responded significantly faster towards newly-moulted female more than to either pre-or inter-moult females, results of the first trial suggest that BC males are able to use different chemical cues to gather information about a conspecific’s gender and can differentiate female’s moult stages. Since BC males responded significantly faster towards newly-moulted females more than to either pre-or inter-moult females, this suggests that females at this particular stage released a distinct sexual pheromone or concentration of pheromone that differed from those pheromones released by both pre- and inter-moult females. In contrast, newly-moulted females prefer the inter-moult BC males which indicate that females have an ability to distinguish the moult status of BC males. Furthermore, it indicates that pheromone characteristics change with the moult status of BC males. Also, newly-moulted females are most likely to be avoiding the potential costs of mate guarding with soft shell BC males. Results obtained from the third trial suggested that a newly-moulted female can discriminate male morphotypes (SM, OC and BC) from their pheromone cues. This indicates that male morphotypes release pheromones which differ from each other in some way. Newly-moulted females responded positively to both SM and BC males with different levels of attraction with the greatest attraction to BC males to BC males suggesting that pheromone released from the BC male may carry information relating to dominance status. Urine is believed to be one of the main carriers of pheromone and is usually released from the antennal gland. Different urine concentrations (0.1, 1.0, 2.0, 3.0, 5.0 and 10µl l-1) of collected urine from BC males were used to test the sexual attraction behaviour of receptive newly-moulted females. Also, the attractant capability of fresh urine following exposure to different temperature regimes (cooled at 4ºC, frozen at -70ºC and heated at 70ºC) was tested. Since newly-moulted female M. rosenbergii were attracted to BC male urine, this indicates the existence of sex pheromone in the fresh urine. Also, it was found that the sexual response of females to fresh urine of BC males was directly proportional to urine concentration with faster responses observed with increasing urine concentrations. At the three fresh urine concentrations 0.1 µl l-1, 1.0 µl l-1 and 2.0 µl l-1, statistical analysis indicated no significant difference (p>0.05) between these three concentrations while a significant (P<0.05) response was to concentrations more than 3.0 µl l-1. This may indicate that these three concentrations were not sufficient to elicit attraction behaviour in newly-moulted females. A concentration of 3.0 µl l-1 of fresh urine is suggested to be a sufficient concentration to elicit a significant sexual attraction under laboratory conditions. Response of newly-moulted female prawns to the various temperature treatments tested declined in response to nominally increasingly degradative treatments. Also, statistical analysis showed that temperature treatment and concentration added both had a significant effect on the response of females. The greatest degradation of urine attractiveness was found with the 70ºC heat treatment. It can be concluded that the pheromone components of prawn urine are friable when exposed to high temperatures. Using light and transmission electron microscopes, ultrastructural observation of the antennal gland (AG) of M. rosenbergii suggests that it has four distinct regions, the coelomosac, the nephridial tubules, the labyrinth and the bladder. Morphological and functional descriptions of each of these regions were compared with those of other aquatic Crustacea.