Is hypoxia a stressor to American bullfrog tadpoles?

Abstract

Pesq. Vet. Bras. 34(4):369-373, abril 2014 369 RESUMO.-[A hipóxia é um estressor para girinos de rã--touro?] Avaliou-se o cortisol em girinos de rã-touro (Lithobates catesbeianus), no estágio de pró-metamorfose ao mecanismo estressor de hipóxia juntamente com captura (1 º experimento) e adensamento (2 º experimento). O experimento de captura foi composto pelos tratamentos: Captura individual com puçá, Captura em massa com puçá e Captura por escoamento, com 3 réplicas simultâneas onde 12 organismos foram amostrados (6 normoxia -coleta imediata de sangue e 6 hipoxia -coleta de sangue após 15 min , com 3 réplicas simultâneas onde 8 animais (4 normoxia e 4 hipoxia) foram amostrados no momento zero (MZ) -coleta de sangue anterior ao experimento, 6 animais/tratamento (3 normoxia e 3 hipoxia) para 4 e 8 dias e 18 animais/tratamento (9 normoxia e 9 hipoxia) para 12 dias. Os valores médios para o cortisol plasmático foram de 1,7 a 5,1ng mL -1 (Experimento de Captura); e 1,0 a 4,2ng mL -1 (Experimento de Densidade). Conclui-se que o marcador biologico de estresse utilizado (cortisol) não foi alterado pelo agente extressor. Alternativamente a resposta a este estímulo pode ser expressa em outro nível hormonal (corticosterona). E a rã-touro apresenta ótima capacidade de se adaptar aos diferentes manejos se comparados a outros organismos aquáticos, o que demonstra a plasticidade destes animais. The aim of this study was to evaluate alterations to the physiological profile of cortisol in pro-metamorphose phase tadpoles of Lithobates catesbeianus exposed to hypoxia stressor in a capture experiment and in a crowding experiment. The capture study was performed by the treatments: stress due to individual capture with a hand net, stress due to batch capture with a hand net and stress due to capture by emptying. Three simultaneous replicates was done witch 12 animals were sampled (6 normoxia -immediately blood collection) and 6 hypoxia -blood collection after 15 min of air exposition) in two collection times with 5 days by intervals. The crowding study was performed by the treatments 1 tadpole L . Three simultaneous replicates was done witch 8 animals (4 normoxia and 4 hypoxia) were sampled in the zero moment (ZM) -blood collection before the experiment, 6 animals/treatment (3 normoxia and 3 hypoxia) to 4 and 8 days and 18 animals/treatment (9 normoxia and 9 hypoxia) to 12 days. The average values to plasmatic cortisol varying from 1.7 to 5.1ng mL -1 (capture study) and 1.0 to 4.2ng mL -1 (crowding study). It concludes that the biomarker tested (cortisol) showed no alterations front of the stressor used. Alternatively, a larger response pattern to these stimuli may have been expressed in another level of an unmeasured hormone (corticosterone). And the bullfrog has great ability to adapt to different management compared to other aquatic organisms, which demonstrates the plasticity of these animals.

Presence of ascites in bullfrog breeders reared and kept on a frog farm

“…With the advancement of knowledge about management and nutrition, frog farming has become a super-intensive activity, with high population densities and strict dependence on balanced foods. However, intensive farming methods have facilitated the emergence of diseases that pose a threat to the technical and economic viability of farms of aquatic organisms (Rottmann et al, 1992;Bondad-Reantaso et al, 2005;Teixeira et al, 2014).…”