Calcium fluxes in Hoplosternum littorale (tamoatá) exposed to different types of Amazonian waters

Fishes that live in the Amazonian environment may be exposed to several kinds of waters: ''black waters'', containing high dissolved organic carbon and acidic pH, ''white waters'', with ten fold higher Ca 2+ concentrations than black waters and neutral pH, and ''clear waters'', with two fold higher Ca 2+ concentrations than black waters and also neutral pH. Therefore, the aim of the present study was to analyze Ca 2+ fluxes in the facultative air-breather Hoplosternum littorale (tamoatá) exposed to different Amazonian waters. Fishes were acclimated in well water (similar to clear water) and later placed in individual chambers for Ca 2+ fluxes measurements. After 4 h, water from the chambers was replaced by a different type of water. Transfer of tamoatás to ion-poor black or acidic black water resulted in net Ca 2+ loss only in the first 2 h of experiment. However, transfer from black or acidic black water to white water led to only net Ca 2+ influxes. The results obtained allowed us to conclude that transfer of tamoatás to ion-poor waters (black and acidic black water) led to transient net Ca 2+ loss, while the amount of Ca 2+ in the ion-rich white water seems adequate to prevent Ca 2+ loss after transfer. Therefore, transfer of tamoatás between these Amazonian waters does not seem to result in serious Ca 2+ disturbance. Os peixes que vivem na Amazônia são expostos a vários tipos de água: águas pretas, contendo grande quantidade de carbono orgânico dissolvido, águas brancas, com concentração de Ca 2+ dez vezes maior que as águas pretas e pH neutro, e águas claras, com concentração de Ca 2+ duas vezes maior que as águas pretas e pH também neutro. Dessa forma, o objetivo deste trabalho foi analisar o fluxo de Ca 2+ no peixe de respiração aérea facultativa Hoplosternum littorale (tamoatá) exposto a diferentes tipos de águas amazônicas. Os peixes foram aclimatados em água de poço artesiano (semelhante à água clara) e depois colocados individualmente em câmaras para medir o fluxo de Ca 2+ . Após 4 h, a água das câmaras foi trocada por um tipo diferente de água. A transferência do tamoatá das águas pobres em íons água preta e preta ácida ou da água branca, rica em íons, para as águas preta e preta ácida, pobres em íons, resulta em uma perda de Ca 2+ apenas nas duas primeiras horas de experimento. Entretanto, a transferência da água preta e preta ácida, para a água branca resulta em um influxo de Ca 2+ . Os resultados obtidos nos permitem concluir que a transferência do tamoatá para as águas preta e preta ácida, pobres em íons, leva a uma temporária perda de Ca 2+ , e a quantidade de Ca 2+ na água branca, rica em íons, é adequada para prevenir sua perda após a transferência. Sendo assim, a transferência do tamoatá entre as águas estudadas não resulta em sérios distúrbios no Ca 2+

Calcium fluxes in Hoplosternum littorale (tamoatá) exposed to different types of Amazonian waters

Fishes that live in the Amazonian environment may be exposed to several kinds of waters: "black waters", containing high dissolved organic carbon and acidic pH, "white waters", with ten fold higher Ca2+ concentrations than black waters and neutral pH, and "clear waters", with two fold higher Ca2+ concentrations than black waters and also neutral pH. Therefore, the aim of the present study was to analyze Ca2+ fluxes in the facultative air-breather Hoplosternum littorale (tamoatá) exposed to different Amazonian waters. Fishes were acclimated in well water (similar to clear water) and later placed in individual chambers for Ca2+ fluxes measurements. After 4 h, water from the chambers was replaced by a different type of water. Transfer of tamoatás to ion-poor black or acidic black water resulted in net Ca2+ loss only in the first 2 h of experiment. However, transfer from black or acidic black water to white water led to only net Ca2+ influxes. The results obtained allowed us to conclude that transfer of tamoatás to ion-poor waters (black and acidic black water) led to transient net Ca2+ loss, while the amount of Ca2+ in the ion-rich white water seems adequate to prevent Ca2+ loss after transfer. Therefore, transfer of tamoatás between these Amazonian waters does not seem to result in serious Ca2+ disturbance. © 2009 Sociedade Brasileira de Ictiologia

Use of salt during transportation of air breathing pirarucu juveniles (Arapaima gigas) in plastic bags

The farming of the Amazonian air breathing fish, Arapaima gigas, has been growing substantially over the last decade in Brazil and other South American countries. Previous study demonstrated that transportation of pirarucu juvenile in plastic bags is a suitable procedure, although it stimulated some stress responses. Therefore the objective of this study was to investigate the addition of salt as a stress mitigator in pirarucu juveniles during transportation in plastic bags. Fish were reared for a month in earthen pond and held in 3 indoor 2000-L depuration tanks for 24 h to allow complete gastrointestinal evacuation, then placed in 30-L polyethylene bags with 10 L of water at a density of 12 fish/bag (40 g/L) with different table salt (NaCl, 97%) concentrations in the water: 0, 1, 3, 5 g/L (3 replicates each concentration). Transportation took 3 h and afterwards fish were transferred to 1-m3 floating cages installed inside an earth pond for recovery. Fish stress responses were evaluated before, during and after transportation procedure, and the analyses performed were: cortisol, glucose, lactate, haematrocrit and waterborne net Na+, Cl-, K+, and Ca2+ fluxes. No mortality was recorded in any treatment during transportation and recovery periods. Cortisol exhibited an increase after transport with 1 g salt/L and at 24 h after transportation for all treatments showing a latency period in their response. Glucose exhibited a similar pattern for all treatments with a significant increase before and after transportation, returning to basal levels in 24 h. Lactate concentrations increased before transportation and after transportation, presenting a significant decrease in all treatments. Addition of salt in the transport water increased Na+, Cl- and Ca2+ net fluxes in pirarucu. Using salt during pirarucu juvenile transportation should be avoided since there is no reduction on stress responses and causes osmoregulatory disturbances. © 2006 Elsevier B.V. All rights reserved

Net ion fluxes in the facultative air-breather Hoplosternum littorale (tamoata) and the obligate air-breather Arapaima gigas (pirarucu) exposed to different Amazonian waters

Fishes that live in the Amazon environment may be exposed to several kinds of water: black water (BW), acidic black water (pH 3.5) (ABW) and white water (WW), among others. The aim of the present study was to analyze net ion fluxes in the facultative air-breather Hoplosternum littorale (tamoata) and the obligate air-breather Arapaima gigas (pirarucu) exposed to different types of water. Fishes were acclimated in well water and later placed in individual chambers containing one type of water for ion flux measurements. After 4 h, the water in the chambers was replaced by a different type of water. The transfer of both species to ABW (independent of previous water exposure) increased net ion loss. Tamoatas transferred from ABW to BW or WW presented a net ion influx, but pirarucus showed only small changes on net ion efflux. These results allow us to conclude that tamoatas and pirarucus present differences in terms of ion regulation but that the general aspects of the ion flux are similar: (1) exposure to ABW led to net ion loss; (2) transfer from BW to WW or vice-versa induced only minor changes on net ion fluxes. These observations demonstrate that any osmoregulatory difficulties encountered by either species during changes between these latter two waters can be easily overcome. © Springer Science+Business Media B.V. 2008

Calcium fluxes in Hoplosternum littorale (tamoatá) exposed to different types of Amazonian waters

Fishes that live in the Amazonian environment may be exposed to several kinds of waters: "black waters", containing high dissolved organic carbon and acidic pH, "white waters", with ten fold higher Ca2+ concentrations than black waters and neutral pH, and "clear waters", with two fold higher Ca2+ concentrations than black waters and also neutral pH. Therefore, the aim of the present study was to analyze Ca2+ fluxes in the facultative air-breather Hoplosternum littorale (tamoatá) exposed to different Amazonian waters. Fishes were acclimated in well water (similar to clear water) and later placed in individual chambers for Ca2+ fluxes measurements. After 4 h, water from the chambers was replaced by a different type of water. Transfer of tamoatás to ion-poor black or acidic black water resulted in net Ca2+ loss only in the first 2 h of experiment. However, transfer from black or acidic black water to white water led to only net Ca2+ influxes. The results obtained allowed us to conclude that transfer of tamoatás to ion-poor waters (black and acidic black water) led to transient net Ca2+ loss, while the amount of Ca2+ in the ion-rich white water seems adequate to prevent Ca2+ loss after transfer. Therefore, transfer of tamoatás between these Amazonian waters does not seem to result in serious Ca2+ disturbance

Using Efinol (R) L during transportation of marbled hatchetfish, Carnegiella strigata (Gunther)

The objective of this experiment was to test the efficacy of a probiotic (Efinol (R) L) during transportation of marbled hatchetfish, Carnegiella strigata. Wild specimens were captured from a small stream and transported for 24 h in plastic fish boxes with a probiotic (10 mg L-1) and probiotic-free water. The boxes were sampled at 3. 12 and 24 h of transport. At the end of the experiment, the survival rate was close to.100%) in both treatments. Dissolved oxygen diminished with time in both treatments, but the probiotic group had significantly higher levels. Conductivity. pH and ammonia increased significantly during the transport. demonstrating higher levels in the probiotic-free group. Fish from both treatments presented very high net Na+ and K+ effluxes after 3 h of transport. At 24 h, net K+ effluxes in fish of the probiotic treatment reached values close to zero and a significantly lower Na+ efflux was observed. Cortisol levels in both treatments at 3 and 12 h were significantly higher than that in control samples. Higher body cortisol levels were observed in the probiotic-frec group than that in the probiotic group at 3 and 12 h. The results demonstrate that addition of a probiotic during fish transport improves water quality and leads to fish presenting a lower stress response intensity