Efeito da densidade populacional sobre as curvas de crescimento de Macrobrachium rosenbergii (De Man) em cultivo semi-intensivo (Crustacea, Palaemonidae)

In this article the length growth curves of Macrobrachium rosenbergii (De Man, 1879) held in different population densities were analysed. Postlarvae prawns were stocked into five 0,02 ha earthen ponds at densities of 4, 8, 12, 16 and 20 ind./m² during six months. Forthnightly, the mean total length of animals from each pond were obtained by means of random samples. For each population the length growth curves and the instantaneous growth rate expressions were determined. The growth rate and the asymptotic maximum length decreased with the stocking density raised. This effect is greater when the density ranges in low levels. The growth decrease can be due to intraspecific competition for life resources and to negative interactions between individuals, as aggressive or social behavior, that increase with the increase prawns density.

Larvas de Scinax rizibilis (Bokermann) (Anura, Hylidae): avaliando o efeito parental

A controlled experiment, related with the mating system of Scinax rizibilis (Bokermann, 1964), was conducted to assess if larval variation could be due to size of male or its ability to manage an amplexus. Adult individuals were caught during breeding activity (from February 1993 to January 1994), in a temporary pond in the municipality of Ribeirão Branco. São Paulo State, southeastern Brazil. The duration of the larval period was not different between tadpoles of large and small males, nor was it different between tadpoles coming from natural or artificial pairs. The reproductive status of the male (if it had managed an amplexus) also did not influence the total length nor the mass of the tadpoles close to metamorphosis. However, tadpoles of larger and heavier males were, on average, approximately 5.5% and 11% larger and heavier, respectively, than tadpoles of smaller males. These results indicate that the breeding system of S. rizibilis could potentially have a directional effect on the larval characteristics.

Crescimento relativo do camarão canela Macrobrachium amazonicum (Heller) (Crustacea, Decapoda, Palaemonidae) em viveiros

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

Ichthyouris voltagrandensis n.sp. (Nematoda: Pharyngodonidae) from Myleus tiete Eigenmann & Norris, 1900 (Osteichthyes: Characidae) in the Volta Grande Reservoir, MG, Brazil

O presente trabalho estudou helmintos parasitos do pacu-manteiga, Myleus tiete (Osteichthyes: Characidae), do Reservatório de Volta Grande, MG, Brasil, com peso médio de 142,6 ± 24,7 g e comprimento total médio de 17,3 ± 1,0 cm. Cinco, dos seis peixes analisados (prevalência de 83,3%), estavam parasitados no intestino com média de 535,6 ± 334,6 nematóides oxiurídeos por peixe. O helminto foi identificado como Ichthyouris voltagrandensis n.sp. (Nematoda: Pharyngodonidae). Difere de I. brasiliensis (Moravec et al., 1992a) por ausência de aleta lateral, maiores dimensões da cauda e da aleta caudal do macho, comprimento do ístmo do esôfago, distância do poro excretor à extremidade anterior e comprimento do espículo. Os ovos são providos de dois longos filamentos situados em apenas um dos pólos e, pela primeira vez, os autores observaram espermatozóides flagelados em machos dissecados. Os autores fornecem tabela comparativa de medidas das cinco espécies do gênero Ichthyouris.

Non-linear growth models for bullfrog tadpoles

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

Desempenho de tricogaster (Trichogaster trichopterus) submetido a diferentes níveis de arraçoamento e densidades de estocagem

O potencial genético para o crescimento de qualquer espécie animal depende das condições ambientais em que são cultivados, como competição por espaço, alimentos e oxigênio. O presente experimento foi conduzido com o objetivo de avaliar o desempenho produtivo de alevinos de tricogaster (Trichogaster trichopterus), uma espécie de peixe ornamental, submetidos a diferentes densidades de estocagem e índices alimentares. Os peixes (com peso médio de 0,56 g ± 0,09 e 0,96 g ± 0,13) foram divididos em dois blocos, submetidos às densidades de 5, 10 e 15 peixes/aquário e alimentados a taxas de 3, 6 e 9% do peso vivo/dia. Os peixes foram alimentados, uma vez ao dia, com ração comercial moída e mantidos em aquários (com capacidade para 100 L) dotados de filtro biológico e aeração, com renovação parcial da água. Os parâmetros físico-químicos da água mantiveram-se dentro da faixa de conforto para a espécie, com diminuição do pH e da condutividade no final do período experimental, para a maior densidade (15 peixes/aquário) e índice alimentar mais elevado (9% p.v./dia). A taxa de arraçoamento afetou significativamente o comprimento final, peso final, ganho de peso, a taxa de crescimento específico e o fator de condição. Os peixes alimentados à base de 9% p.v./dia apresentaram os melhores resultados. Para as diferentes densidades de estocagem, apenas o fator de condição apresentou diferença significativa, com os melhores resultados para os peixes cultivados à densidade de 10 peixes/aquário, em relação aos cultivados à densidade de 15 peixes/aquário. Não foram observadas interações significativas entre os índices alimentares e as densidades de estocagem.

SYNAPTONEMAL COMPLEX-ANALYSIS OF THE SEX BIVALENT IN GOATS

Synaptonemal complex (SC) analysis of XY pairing in the goat (Capra hircus; 2n = 60) was investigated by electron microscopy for the first time in this species. Synapsis of the X and Y chromosomes begins during the mid-late zygotene stage as the autosomes complete their pairing. Only a small portion of the total length of the Y is paired with the X chromosome at this time. By the early pachytene, almost 90% of the Y is paired with the X. All the observed stages of the sex bivalent pairing showed the structural difference between the differential and pairing regions. In the pairing region, a synaptonemal complex is formed, while in the differential region the chromosome axes remain free.

Identification and characterization of different accessions of itchgrass (Rottboellia cochinchinensis)

Studies were conducted to identify and characterize different accessions of itchgrass. Seeds were collected in the counties of Aramina, Campinas, Dumont, Igarapava, Jaboticabal, and Ribeirao Preto, all in the state of São Paulo, Brazil. Accessions were characterized based on dimensions of their stomata, stomatal index (SI), and length and width of their seed (caryopses and husk). Chromosome number and length also were determined, and accessions were further differentiated using molecular markers (polymerase chain reaction [PCR]). Itchgrass from Ribeirao Preto had much longer and narrower seeds than those from the other locations, and their husks were longer as well. Accessions had similar SIs, both on the abaxial and adaxial leaf surfaces. Stomata from Campinas and Igarapava accessions were longer and wider, whereas those from Dumont and Ribeirao Preto were similar and smaller than all others. The accession from Ribeirao Preto is diploid (2n = 20); the rest are polyploid, with the total length of chromosomes smaller than all others. These differences were confirmed by molecular differentiation (PCR).

Reproductive biology and seasonal distribution of Mustelus schmitti (Elasmobranchii : Triakidae) in the Rio de la Plata oceanic front, south-western Atlantic

The population structure and reproductive biology of Mustelus schmitti was analysed during autumn (1994, 1995) and spring (1994) in the Rio dc la Plata occanic front. The samples consisted mainly of a adult males and immature females, indicating that nursery areas are Situated elsewhere. In autumn, the highest female densities occurred between 36 degrees S and 35 degrees S, with densities decreasing further south, and high male densities occurred over all latitudes of the study area. In Spring, both Sexes occurred north of latitude 36 degrees 30 degrees S. Males attained Maturity at. 59 cm total length (TL), and females at 72 cmTL Litter size varied From one to ten in spring and two to nine in autumn, With embryos ranging from 9 to 26 cm and 7 to 26 cm TL respcctivcly the mean TL of embryos was significantly higher in spring (22 cm), suggesting that parturition Occurs ill late spring and summer. Litter size was found to Increase with female TL..

Embryos of common thresher shark Alopias vulpinus in southern Brazil, south Atlantic Ocean

Eight embryonic thresher sharks Alopias vulpinus (53.9-124 cm total length) were collected from two females caught by commercial longline off southern Brazil in September and November 2004. Morphometric measurements are provided. (c) 2006 the Authors.

Notes on the feeding habits of the skate Rioraja agassizi (Chondrichthyes, Rajidae) off southeastern Brazil

Feeding habits of the skate Rioraja agassizi were analyzed in southeastern Brazil from samples obtained along Silo Paulo coast. A total of 258 specimens were examined, ranging between 96 and 532 mm total length. About 57.85% were females and 42.15% were males, resulting in a 1:1.37 sex-ratio to females. From 223 stomachs collected (94 males and 129 females) empty stomachs represented only 1.4%. Nine prey categories were identified: Polychaeta, Copepoda, Cumacea, Isopoda, Gammaridea, Dendrobranchiata, Brachyura, Teleostei, and one non-animal category (non-identifiable items). Crustaceans were the most important item, indicating that the species has a carcinophagic preference. The presence of fish was just verified in juveniles and some adult individuals, with predominance in summer. Sex, maturity stage and seasonality did not influence the feeding habits of the species.

Daily sperm production and testicular morphometry in goats according to external scrotal conformation

The present study aimed to compare testicular histology and the testicular cell population as well as spermatogenic efficiency in goats with different scrotal conformations. Eighteen goats were divided into 3 groups: Group I - goats without bipartition of the scrotum, Group II - animals with bipartition of the scrotum up to 50% of the testicular length, Group III - goats with scrotal bipartition more than 50% of the testicular length. In goats in Groups I, II and III, the values for the volume density of seminiferous epithelium were 68.9 +/- 0.6%, 71.5 +/- 2.8% and 73.4 +/- 4.7% (P < 0.05), the height of the seminiferous epithelium were 60.2 +/- 4.9 mu m, 61.0 +/- 5.0 mu m and 73.1 +/- 6.6 mu m (P < 0.05), total length of seminiferous tubules found for Groups I, II and III were 2091.9 +/- 27 m, 2172.5 +/- 24.1 m, and 2340.1 14 m (P < 0.05), number of Sertoli and Leydig cells were 1.8 +/- 0.4 x 10(9) and 1.4 +/- 0.1 x 10(9), 2.2 +/- 0.4 and 2.2 +/- 0.7 x 10(9), and 2.5 +/- 0.1 10(9) and 2.3 +/- 0.510(9)(P < 0.05)and daily sperm production observed were 2.1 0.3 x 109, 2.8 0.4 x 109, and 3.1 0.7 x 109 (P < 0.05). In conclusion, goats with greater scrotal bipartition have a greater capacity to produce reproductive cells that is reflected in a greater reproductive potential. (C) 2011 Elsevier B.V. All rights reserved.

Aspectos da reprodução e alimentação de Neoplecostomus microps (Loricariidae, Neoplecostominae) na microbacia do Ribeirão Grande, serra da Mantiqueira oriental (Estado de São Paulo)

Reproduction and feeding aspects of Neoplecostomus microps (Loricariidae, Neoplecostominae) in the Ribeirao Grande system, eastern Serra da Mantiqueira (São Paulo State). The Ribeirao Grande system is located in the slope of the Serra da Mantiqueira and is surrounded by Atlantic forest. Eight sites were surveyed in the Ribeirao Grande system, during the winter (July 2001), spring (October 2001), summer (February 2002) and fall (April 2002). Samples were made with an electrofishing device. Gonad maturation, levels of stomach fullness and fat content were analyzed and their distributions reported in an annual cycle. Neoplecostomus microps has a spawning in the spring through to summer. The size at sexual maturity is about 5.9 cm total length for males and 6.9 cm for females. The high values in October and February by the gonadosomatic index and the relative condition factor coincided with the spawning period. In the diet of N. microps were found Diptera larvae (Simulium, Chironomus), Plecoptera nymphs and Coleoptera aquatic Larvae (Psephenus). The increased feeding from summer to fall provided fat accumulation. During subsequent seasons, fish may utilize visceral fat reserves for maintenance and reproduction. The reproductive pattern and feeding are interpreted as being an adaptation with respect to temporal and spatial variation and food availability.

Co-feeding of pacu, Piaractus mesopotamicus Holmberg (1887), larvae with Artemia naupili and a microencapsulated diet

Aiming at a precocious substitution of live prey by artificial diet, a 20-day experiment with pacu, Piaractus mesopotamicus, larvae using co-feeding and abrupt weaning strategies was set up. At the end of the experiment, larvae fed Artemia showed the best results (P < 0.05) in weight, total length and biomass, compared with other treatments. Larvae fed exclusively a microencapsulated diet never ingested the diet. Diet ingestion in co-fed and abrupt-weaned larvae was low, but did increase during the experiment; however, Artemia influenced diet ingestion on co-fed larvae. Careful considerations should be given to diet processing and formulation to ensure survival and growth of larvae fed exclusively on prepared diets. © 2005 by The Haworth Press, Inc. All rights reserved.

The reproductive biology of Diplodus argenteus (Sparidae) in the coastal upwelling system of Cabo Frio, Rio de Janeiro, Brazil

The reproductive biology of the seabream Diplodus argenteus, a dominant coastal fishery species, was investigated over two consecutive seasons (2001-2002) at Cabo Frio, Brazil, a low-latitude upwelling system. The sex ratio was dominated by females (1.4:1.0) and the length-at-50% sexual maturity (females) was 203mm total length. Females were multiple spawners and the reproductive pattern appeared to be digynous protandrous hermaphroditism. Monthly variations in gonadosomatic index and proportion of ripe females indicated that reproductive activity occurred from late winter to summer (August-February), following coastal upwelling. Copyright © NISC Pty Ltd.