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Aquaponics is the cultivation technique that integrates aquaculture with hydroponics. The present work compared two plant production cycles of a hydroponic component of an aquaponic system (tilapia-lettucecucumbers) vs. a hydroponic system. The tilapia growth trial lasted 22 weeks in the aquaponic system, during which two plant production cycles -lettuce-cucumber- (seven weeks) were performed. Water quality and environmental variables were recorded, evaluating weight growth and biomass produced in fish rearing. Leaf number, height, and weight were determined in lettuce plants. Stem length and fresh weight were measured in cucumber plants; length, fresh weight, and diameter were determined in cucumber fruit. The results showed that the average tilapia biomass per tank was 33.76 kg m-3 with an average final weight of 592.26 ± 25.45 g fish-1. Lettuce production (plants ha-1 ) was higher in aquaponics than hydroponics during the first cycle, while in the second one, it was greater in hydroponics. Significant differences (ANOVA, P < 0.05) resulted between treatments in both cucumber production cycles with larger biomass growth in hydroponics than in aquaponics. Cucumber fruit showed larger weight (212.52 ± 18.89 g) and length (14.15 ± 1.75 cm) in hydroponics, thus greater yield (4.97 t ha-1 ); hydroponics-grown cucumber plants had longer stem lengths (292.51 ± 8.73 cm). In conclusion, the hydroponic system had higher plant production. However, aquaponics provided a double benefit since it produced fish and plants, and the plants used waste from fish rearing without contaminating the environment. [ABSTRACT FROM AUTHOR]

Intensive aquaculture recirculating systems produce effluents (dissolved and particulate solids) with concentrations of nitrogen and phosphorus, a potential source of pollution if they are not properly treated. The sludge and nutrient removal by anaerobic digestion has become an alternative for aquaculture sludge digestion and stabilization. In this study we determine the effect of four different pretreatments (alkaline, mechanical, thermal and biological) in sludge reduction and denitrification efficiency, biogas production and nitrogen and phosphorus dynamics from a hyper-intensive Nile tilapia (Oreochromis niloticus, Linnaeus, 1758) culture in 15 days experiments, one per month for one year. After application of pretreatments in aquaculture sludge, an increase in the release of total ammonia nitrogen was obtained with respect to the control, in the same way nitrate removal was obtained in all pretreatments (˃90%), The increase in total suspended solids removal was higher in pretreatment (˃20.3%) compared to control (14.6%), As well as the biogas production increase, being the biological pre-treatment where the highest concentration was obtained (45.18 cm3 L-1) The results indicate that the application of pre-treatments in the aquaculture effluents improves the denitrification processes and anaerobic digestion and can reduce the hydraulic retention time. [ABSTRACT FROM AUTHOR]

Karyotypes of the purple snails Plicopurpura pansa and Plicopurpura columellaris (Gastropoda: Muricidae). The karyotypes of the purple snails Plicopurpura pansa (Gould, 1853) and P. columellaris (Lamarck, 1816) were established from 17 and 13 adults, respectively; and from eight capsules with embryos of P. pansa. In P. pansa were counted 59 mitotic fields in the adults and 127 in embryos; and 118 fields in P. columellaris. Chromosome numbers from 30 to 42 were observed in both species. Such a variation was notorious in each sample and there was no evidence of any relationship with tissue (gill, muscle and stomach). Both species has a typical modal number of 2n=36 chromosomes. Five good quality chromosome spreads were selected from adults of each species to assemble the karyotype. Classic cytogenetics statistics like relative lengths, arm ratio, centromeric index and the difference between long and short arms are presented. There were three pairs of metacentric and fifteen pairs of telocentric chromosomes in both species. This classification was not strong enough, so the chromosome complement by species was divided in four groups ("a", "b", "c" and "d") on the basis of relative lengths (p+q). A comparison of p+q in each chromosome pair was estimated within and between species by two ways analysis of variance and Tukey tests (P<0.05). Significant differences were identified among chromosome groups in each species; the differences between species were given by the first three pairs of chromosomes (group "a" biarmed) and the last two pairs (group "d" uniarmed). Deviations in chromosome number and relative lengths probably are given by chromosome rearrangements, related with chromosome polymorphism and presence of the atypical microchromosome "B". The fundamental number in both species was characterized by 42 chromosome arms. No sex chromosomes were identified. [ABSTRACT FROM AUTHOR]

The karyotypes of the purple snails Plicopurpura pansa (Gould, 1853) and P. columellaris (Lamarck, 1816) were established from 17 and 13 adults, respectively; and from eight capsules with embryos of P. pansa. In P. pansa were counted 59 mitotic fields in the adults and 127 in embryos; and 118 fields in P columellaris. Chromosome numbers from 30 to 42 were observed in both species. Such a variation was notorious in each sample and there was no evidence of any relationship with tissue (gill, muscle and stomach). Both species has a typical modal number of 2n=36 chromosomes. Five good quality chromosome spreads were selected from adults of each species to assemble the karyotype. Classic cytogenetics statistics like relative lengths, arm ratio, centromeric index and the difference between long and short arms are presented. There were three pairs ofmetacentric and fifteen pairs oftelocentric chromosomes in both species. This classification was not strong enough, so the chromosome complement by species was divided in four groups ("a", "b", "c" and "d") on the basis of relative lengths (p+q). A comparison of p+q in each chromosome pair was estimated within and between species by two ways analysis of variance and Tukey tests (P < 0.05). Significant differences were identified among chromosome groups in each species; the differences between species were given by the first three pairs of chromosomes (group "a" biarmed) and the last two pairs (group "d" uniarmed). Deviations in chromosome number and relative lengths probably are given by chromosome rearrangements, related with chromosome polymorphism and presence of the atypical microchromosome "B". The fundamental number in both species was characterized by 42 chromosome arms. No sex chromosomes were identified.