Brothers are better than nothing: first report of incestuous mating and inbreeding depression in a freshwater decapod crustacean

This study aimed at evaluating the effect of one generation of full-sibling mating on traits related to the fitness of the gregarious freshwater shrimp Neocaridina davidi, both under optimal and stressful (i.e. starvation) laboratory conditions. Females were maintained either with their brothers (Inbreeding treatment) or non-brothers (Outbreeding treatment), and the first and second broods were used to evaluate egg production and juvenile quality, respectively. The latter was analyzed in a 60-day period following hatching under optimal rearing conditions, and in a 20-day period following hatching under food deprivation conditions. All surviving females from both treatments mated and spawned, indicating that mating with brothers was as likely as mating with non-brothers. With respect to offspring production, inbreeding had no effect on fecundity and fertilization success, but negatively affected the number of hatched juveniles. These results suggest that egg loss was higher in inbred clutches, possibly due to lower embryonic survival. On the other hand, the effect of inbreeding on growth was absent for embryos and for juveniles under optimal rearing conditions, while it was significant for juveniles starved for 10 consecutive days following hatching. Inbreeding depression for survival was only detected in juveniles from stages S8-S9 under optimal rearing conditions. Overall, the present results show that N. davidi fitness decreases after one generation of full-sibling mating. The use of a potentially weak food deprivation protocol and/or the evaluation of only one inbred generation could explain the absence or subtle inbreeding depression for some of the evaluated traits. No evident relationship between life-history traits and the existence and magnitude of inbreeding was found when comparing our results with those previously reported in high-fecundity marine crustaceans and low-fecundity terrestrial crustaceans.Fil: Tropea, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Marciano, Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Lopez, Laura Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; Argentin

Effect of long-term injection of dopamine on the ovarian growth of Cherax quadricarinatus juvenile females (Parastacidae, Decapoda).

The neurotransmitter dopamine (DA) modulates many physiological processes in decapod crustaceans, including reproduction. This study was aimed at evaluating whether the long-term injection of DA affects ovarian growth in the freshwater crayfish Cherax quadricarinatus. Three experiments were performed with females of different mean initial size: 4.15 g (Group A); 9.65 g (Group B); and 13.98 g (Group C). Treated females were injected with DA and control females with physiological saline twice a week for 90 (Group B), 105 (Group A) and 120 (Group C) days. At the end of the experiments, the animals were killed, and the stage of ovarian development, gonadosomatic index, and mean oocyte diameter were determined. DA had a differential effect according to female size: it negatively affected ovarian growth of females in a weight range of 4?14 g and had no effect on ovarian maturation when injected to females with an initial weight of 14 g. The results are compared with previous reports in freshwater decapod crustaceans.Fil: Tropea, Carolina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biologia Experimental y Aplicada; ArgentinaFil: Lopez, Laura Susana. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biologia Experimental y Aplicada; Argentin

Female Growth and Offspring Quality over Successive Spawnings in a Caridean Shrimp Neocaridina davidi (Decapoda, Atyidae) with Direct Development

This study analyzed the quality of recently spawned eggs and of juveniles over five and six consecutive spawns, respectively, in a caridean shrimp Neocaridina davidi with direct development. The potential energetic antagonism between reproduction and somatic growth was also evaluated. The number of eggs per spawn per female was highest in the first spawn, while the number of recently hatched juveniles per spawn per female declined in the sixth spawn. Lower lipid concentration and energy content were detected in eggs of the fourth and fifth spawns, which may indicate for the first time a decrease in maternal provisioning as a result of multiple spawning in a decapod with direct development. This result had no effect on the size of eggs or of recently hatched juveniles, nor on the growth performance of juveniles during a 30-day period following hatching. Lipids were the most abundant biochemical component of eggs, followed by proteins and glycogen; the relative proportion of each component was probably related to embryonic development type. Egg volume was unsuitable as an indicator of nutrient content, as no correlation was found between these variables. The physiological costs of reproduction were evident from the lower energy content of females that reproduced versus females that remained virgin. The lower body weight of the reproductive females at the end of the experiment showed that allocation of resources to reproduction occurred at the expense of somatic growth. To our knowledge, this is the first empirical demonstration of a decapod with direct development.Fil: Tropea, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Lopez, Laura Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; Argentin

Effect of social environment on sexual differentiation in the highly gregarious red cherry shrimp (Neocaridina davidi)

Studies on social control of functional sex in crustaceans are scarce and focused on hermaphroditic species. Hence, the objective of this study was to determine whether adult sex ratio affects juvenile sexual differentiation in a gonochoristic caridean shrimp, Neocaridina davidi (Bouvier 1904). We tested two alternative hypotheses: (1) that undifferentiated juveniles become males when reared in the presence of adult females and vice versa; and (2) that the presence of adult males affects juvenile sexual differentiation through androgenic gland secretions. Newly hatched juveniles were maintained with adult males or adult females during a 50-day period, after which they were sexed. In both treatments, juvenile sex ratios showed no deviations from the expected 1:1 relationship. This suggests that adult sex ratio is not a selective force determining juvenile phenotypic sex, even though mating opportunities may be null for juveniles differentiating into the sex of surrounding adults. The 1:1 sex ratio observed in broods reared with adult males and adult females also suggests that the potential chemical cues released by adults have neither masculinizing nor feminizing effects on undifferentiated juveniles. Present results reject our initial hypotheses and are consistent with a strong genetic basis of juvenile sexual differentiation in caridean shrimps.Les études sur le contrôle qu’exerce l’environnement social sur le sexe fonctionnel chez les crustacés sont rares et portent sur des espèces hermaphrodites. L’objectif de la présente étude consistait donc à déterminer si le rapport de masculinité des adultes a une incidence sur la différenciation sexuelle des juvéniles chez la crevette cerise (Neocaridina davidi (Bouvier, 1904)) (Decapoda, Caridea) gonochoriste. Nous avons testé les deux hypothèses suivantes : (1) les juvéniles non différenciés deviennent des mâles quand ils sont élevés en présence de femelles adultes et vice versa; (2) la présence de mâles adultes influence la différenciation sexuelle des juvéniles par l’entremise de sécrétions des glandes androgènes. Des juvéniles nouvellement éclos ont été maintenus en présence de mâles adultes ou de femelles adultes pendant 50 jours, après quoi leur sexe a été déterminé. Pour les deux traitements, les rapports de masculinité ne présentaient aucun écart par rapport à la relation de 1:1 attendue. Cela porte à croire que le rapport de masculinité des adultes n’est pas une force de sélection déterminante du sexe phénotypique des juvéniles, même si les occasions d’accouplement peuvent être inexistantes pour les juvéniles qui prennent le sexe des adultes qui les entourent. Le rapport de masculinité de 1:1 observé pour les pontes élevées en présence de mâles adultes ou de femelles adultes donne aussi à penser que d’éventuels signaux chimiques émis par les adultes n’ont pas d’effet masculinisant ni féminisant sur les juvéniles non différenciés. Les résultats de l’étude infirment nos hypothèses initiales et concordent avec l’interprétation d’une forte base génétique de la différenciation sexuelle des juvéniles chez les crevettes caridines.Fil: Tropea, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: López Greco, Laura Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; Argentin

Recovery growth of Cherax quadricarinatus juveniles fed on two high-protein diets: Effect of daily feeding following a cyclic feeding period on growth, biochemical composition and activity of digestive enzymes

Recovery growth of C. quadricarinatus juveniles was evaluated during a daily feeding period that followed a cyclic feeding period, by the analysis of the biochemical composition and structure of the hepatopancreas, and the activity of digestive enzymes. Two different diets were evaluated: diet A (49% crude protein) and diet B (38% crude protein), and juveniles were subjected to one of the following feeding regimes for each diet: DF, under which they were daily fed throughout the experimental period (120 days); and 4F/4D, under which they were fed for 4 days followed by 4 days of food deprivation in repeated cycles from day 1 to day 45, and daily fed from day 45 to day 120. Juveniles under the 4F/4D regime showed compensatory growth and reached the same body mass of control juveniles (i.e. complete catch-up growth) at the end of the experiment. This physiological response was not affected by the two high-protein diets tested, and it may be at least partly explained by an improved food conversion ratio, a similar ability to digest and absorb nutrients and an increased efficiency in protein digestion with respect to control juveniles. The 4F/4D regime had no negative effects on the nutritional state and health of red claw crayfish, which confirms the high tolerance of the species to food deprivation. The present results are important from an economical point of view since they show that it is possible to significantly reduce the amount of food offered in culture systems, and consequently reduce production costs, without affecting juvenile growth.Fil: Stumpf, Liane. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Tropea, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Lopez, Laura Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; Argentin

Embryonic and larval development of the caridean shrimp Palaemon argentinus (Decapoda, Caridea): Effects of salinity and diet

The caridean shrimp Palaemon argentinus is a species of commercial and ecological interest. Its numerous larval stages, the lack of knowledge on their nutritional requirements, and their ability to survive in a wide range of salinities raise questions on the optimum conditions for larval rearing in captivity. The present study was aimed at evaluating embryonic development under different salinities and larval development under different combinations of salinities and diet regimes, in order to define alternative, cheaper culture conditions. We tested salinities usually encountered by the species in natural habitats (0.1, 1 and 5 ppt) and a highly protein-inert diet (Tetracolor®) as a potential replacement for live food (nauplii of Artemia salina). The incubation period and fecundity were similar among salinity treatments. Overall, the number of survival days and percentage of zoeae that moulted two, three and four times were higher when embryogenesis occurred at 5 ppt and when larvae were exposed to 5 ppt. These results suggest that the conditions experienced by embryos affect the performance of the first larval stages, and probably reflect the lower energetic requirements of zoeae to osmoregulate as water and haemolymph osmolarity become closer. On the other hand, larval performance was better when fed A. salina nauplii than Tetracolor®. The latter may not cover the nutritional requirements of zoeae or may have low digestibility due to insufficient enzymes in the undeveloped larval digestive system. Based on the present results, we conclude that a salinity of 5 ppt combined with a diet consisting of Artemia sp. nauplii is optimal for larval culture at early stages.Fil: Tropea, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Stumpf, Liane. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: López Greco, Laura S.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; Argentin

Effect of temperature on biochemical composition, growth and reproduction of the ornamental red cherry shrimp Neocaridina heteropoda heteropoda (Decapoda, Caridea).

The effect of water temperature on biochemical composition, growth and reproduction of the ornamental shrimp, Neocaridina heteropoda heteropoda, was investigated to determine the optimum temperature for its culture. The effect of embryo incubation temperature on the subsequent performance of juveniles was also evaluated. Ovigerous females and recently hatched juveniles (JI) were maintained during egg incubation and for a 90-day period, respectively, at three temperatures (24, 28 and 32 °C). Incubation period increased with decreasing water temperature, but the number and size of JI were similar among treatments. At day 30 of the 90-day period, body weight and growth increment (GI) at 24 °C were lower than those at 28 and 32 °C. On subsequent days, GI at 24 °C exceeded that at 28 and 32 °C, leading to a similar body weight among treatments. These results suggest growth was delayed at 24 °C, but only for 30 days after hatching. The lipid concentration tended to be lowest, intermediate and highest at 28, 32 and 24 °C, respectively, possibly as a consequence of the metabolic processes involved in growth and ovarian maturation. Protein and glycogen concentrations were similar among treatments. Both the growth trajectory and biochemical composition of shrimps were affected by the temperature experienced during the 90-day growth period independently of the embryo incubation temperature. During the growth period, shrimps reached sexual maturity and mated, with the highest proportion of ovigerous females occurring at 28 °C. All the females that matured and mated at 32 °C lost their eggs, indicating a potentially stressful effect of high temperature on ovarian maturation. Based on high survival and good growth performance of shrimps at the three temperatures tested over the 90-day period it is concluded that N. heteropoda heteropoda is tolerant to a wide range of water temperatures, with 28 °C being the optimum temperature for its culture

Egg production in relation to paternal weight in a freshwater caridean shrimp (Decapoda)

In diverse invertebrate species, sperm quantity and quality are positively correlated with male size, egg fertilization rates being consequently affected by paternal weight. This factor may also have an indirect effect on egg quality, because females could adjust the quantity of yolk stored in oocytes before spawning according to their partner attractiveness. The objective of the present study was to determine whether paternal weight influences egg production in a freshwater crustacean with external egg fertilization, the caridean shrimp Neocaridina davidi. Virgin females weighing 60-100 mg were paired with virgin males weighing 20-50 mg. The number (total and fertilized), size (volume, wet and dry weight) and carotenoid content of eggs were recorded for each pair. Paternal weight was not associated to any of the evaluated egg variables, while maternal weight showed a positive correlation with egg number and a negative correlation with egg carotenoid content. The percentage of fertilized eggs was similar and near 100% for all paternal sizes, which indicates that small mature males provided enough good-quality sperm to fertilize almost all the oocytes laid by females, similarly to larger males. The relatively low fecundity of N. davidi females may explain, at least in part, the absence of sperm limitation even under a hypothetical decrease in sperm supply by smaller males. In addition, paternal weight had no effect on egg volume, weight and carotenoid content, which suggests that females do not modulate the total amount of biochemical reserves allocated to the maturing ovary as a function of their partner size. Present results are the starting point for a future evaluation of sperm production, in terms of quantity and quality, in males of different size and physiological condition.Fil: Tropea, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Sganga, Daniela Eliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: López Greco, Laura Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; Argentin