Flavia Sant’Anna Rios

Changes in gut gross morphology of traíra, Hoplias malabaricus (Teleostei, Erythrinidae) during long-term starvation and after refeeding

Adult traíra (Hoplias malabaricus) were submitted to different periods of food deprivation (from 30 to 240 days) and refed for 30 days after 90 and 240 days of starvation. Stomach length remained constant during all the experimental period. However, the intestine length was significantly reduced after 30 days of food deprivation. Normal length was not recovered after refeeding. The number of pyloric caeca did not change significantly. Conversely, caeca thickness decreased after 150 days of starvation and their length decreased after 180 days. After refeeding, however, the pyloric caeca recovered original thickness. In fish refed after 240 days of starvation the length of these structures seemed to present compensatory growth, becoming longer than in the control group.

Effect of temperature acclimation on the liver antioxidant defence system of the Antarctic nototheniids Notothenia coriiceps and Notothenia rossii.

The aim of this study was to determine whether endemic Antarctic nototheniid fish are able to adjust their liver antioxidant defence system in response to the temperature increase. The activity of the superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and glutathione reductase (GR) enzymes as well as the content of non-enzymatic oxidative stress markers such as reduced glutathione (GSH), lipid peroxidation (LPO) and protein carbonyl (PC) were measured in the liver of two Antarctic fish species, Notothenia rossii and Notothenia coriiceps after 1, 3 and 6days of exposure to temperatures of 0°C and 8°C. The GST activity showed a downregulation in N. rossii after 6days of exposure to the increased temperature. The activity profiles of GST and GR in N. rossii and of GPx in N. coriiceps also changed as a consequence of heating to 8°C. The GSH content increased by heating to 8°C after 3days in N. coriiceps and after 6days in N. rossii. The content of malondialdehyde (MDA), a LPO marker, showed a negative modulation by the heating to 8°C in N. rossii after 3days of exposure to temperatures. Present results show that heating to 8°C influenced the levels and profiles of the antioxidant enzymes and defences over time in the nototheniid fish N. rossii and N. coriiceps.

Development of the neotropical catfish Rhamdia quelen (Siluriformes, Heptapteridae) incubated in different temperature regimes

The developmental stages for the embryonic and larval periods of the silver catfish (Rhamdia quelen) kept at different temperatures (21, 24, 27 and 30 degrees C) are described. Fish were analysed under light and scanning electron microscopy. For embryonic development, we described 25 stages, which were grouped into seven periods named zygote, cleavage, blastula, gastrula, segmentation, pharyngula and hatching periods. For larval development, we defined three stages (early, mid, and late larvae). Additionally, the main ontogenetic events during the post-larvae and early juvenile periods were also described. This species presents a well developed lateral line and chemosensory systems that grow up during the larval period, maturing in the post-larvae. All tested temperatures are viable to R. quelen development, but a shorter incubation period was necessary to complete the development at lower temperatures. However, some malformations (heart edema) were verified at 30 degrees C.

Spatial, seasonal and ontogenetic variation in the diet of Astyanax aff. fasciatus (Ostariophysi: Characidae) in an Atlantic Forest river, Southern Brazil

Este estudo descreveu os habitos alimentares do lambari Astyanax aff. fasciatus. Foram comparadas as composicoes alimentares de especimes de dois sitios (A e B) de um rio no sul do Brasil de acordo com o tamanho dos individuos e do periodo sazonal. As coletas foram realizadas mensalmente de marco de 2005 a fevereiro de 2006, sendo o conteudo estomacal de 290 exemplares analisado. A dieta de A. aff. fasciatus foi composta basicamente por plantas e insetos, especialmente fragmentos de folhas, sementes, frutos, algas filamentosas, insetos aquaticos e terrestres e fragmentos de insetos. No sitio A, os itens de maior importância foram fragmentos de insetos e plantas. Ao contrario no sitio B, fragmentos de plantas foram mais representativos. Em geral, todos os itens de origem animal apresentaram os maiores valores do indice alimentar no sitio A, enquanto que no sitio B detritos e gramineas foram mais abundantes. A composicao dos itens ingeridos variou sazonalmente, sendo a maior diversidade registrada durante o periodo da primavera para ambos os sitios. Individuos pequenos preferiram itens de origem animal enquanto que os maiores consumiram principalmente itens de origem vegetal. De acordo com seu tamanho A. aff. fasciatus neste estudo pode ser considerada uma especie com tendencias a insetivoria quando imaturo, ou a herbivoria quando adulto. No entanto, seu habito alimentar pode ser flexivel de acordo com a disponibilidade de recursos, mostrando ampla variacao tanto ontogenetica quanto espacial e temporal.

Utilization of endogenous reserves and effects of starvation on the health of Prochilodus lineatus (Prochilodontidae)

Prochilodus lineatus Valenciennes (curimbatá) is an important migratory Neotropical fish. It does not feed during spawning migration, and often survives after spawning. The mobilization of energy reserves and some effects of starvation (zero to eight weeks) on fish health were experimentally evaluated. Hepatic glycogen and lipids from the perivisceral fat bodies were the main reserves mobilized during the first four weeks of fasting. During this period, somatic indices and blood parameters showed that fish health was not significantly affected. However, after five weeks of food deprivation, the main energy reserves were depleted and the fish became anaemic. The loss of muscle mass indicates that protein breakdown was an important energy source after the reduction of hepatic and perivisceral reserves. Mortality was increasingly observed from seven weeks of starvation. Prior accumulation of high amounts of reserves is essential to allow movements for long distances during spawning migrations in this species.

Spatial and temporal variation in krill consumption by the Antarctic fish Notothenia coriiceps , in Admiralty Bay, King George Island

An index of integrated food preferences (IFA) of Notothenia coriiceps Richardson at two sites in Admiralty Bay (Ipanema and Smok Point), calculated for two sequential summers, showed that during 1998/99, the most important food item was Euphausia superba (krill) at both Ipanema (IFA = 0.83) and Smok Point (IFA = 0.75), while the sum of all other food items was significantly smaller (IFA respectively 0.21 and 0.26). Macroalgae, gammarid amphipods and gastropods dominated the diet in the summer 1999/00 (IFA respectively 0.32, 0.32 and 0.21), at Ipanema, while macroalgae were dominant at Smok (IFA = 0.67), where krill and amphipods were secondary prey (IFA respectively 0.12 and 0.14) and gastropods were absent. Thus, the diet composition of N. coriiceps can possibly be used as an indicator of the presence of pelagic krill swarms.

Effects of food deprivation in muscle structure and composition of traíra (Hoplias malabaricus): potential implications on flesh quality

Hoplias malabaricus (traira) were experimentally starved (0 to 240 days) and subsequently re-fed for 30 days (after 90 and 240-d fasting). Long-term starvation produced minor changes in muscle composition, but shrinkage of muscle fibres was a conspicuous result. The diameter of muscle fibres decreased gradually and the spaces among them increased as the starvation period progressed. After re-feeding, fish prior starved for 90 days presented partial restoration on diameter of muscle fibres. However, the fibres remained shrunken after re-feeding following 240-d fasting. While the lipid content did not change, the protein levels fell after 240-d fasting, but they were restored after re-feeding