Metabolic rate and thermal tolerance in two congeneric Amazon fishes: Paracheirodon axelrodi Schultz, 1956 and Paracheirodon simulans Géry, 1963 (Characidae)

详细信息    查看全文

• 作者：D. F. Campos ; T. F. Jesus ; D. Kochhann ; W. Heinrichs-Caldas ; M. M. Coelho…
• 关键词：Thermal niche ; Tropical fishes ; Stenothermal species ; Hypoxia tolerance ; Oxygen ; and capacity ; limited thermal tolerance
• 刊名：Hydrobiologia
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：789
• 期：1
• 页码：133-142
• 全文大小：
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Freshwater & Marine Ecology; Ecology; Zoology;
• 出版者：Springer International Publishing
• ISSN：1573-5117
• 卷排序：789

文摘

Temperature is the main factor affecting the distribution of the sympatric Amazon fishes Paracheirodon axelrodi and Paracheirodon simulans. Both species are associated with flooded areas of the Negro river basin; P. axelrodi inhabits waters that do not exceed 30°C, and P. simulans lives at temperatures that can surpass 35°C. The present work aimed to describe the biochemical and physiological adjustments to temperature in those species. We determined the thermal tolerance polygon of species acclimated to four temperatures using critical thermal methodology. We also determined the chronic temperature effects by acclimating the two species at 20, 25, 30, and 35°C and measured the critical oxygen tension (PO_2crit) for both species. Additionally, we evaluated the metabolic rate and the enzymes of energy metabolic pathways (CS, MDH, and LDH). Our results showed a larger thermal tolerance polygon, a higher energetic metabolic rate, and higher enzyme levels for P. simulans acclimated to 20 and 35°C compared to P. axelrodi. Paracheirodon simulans also presented a higher hypoxia tolerance, indirectly determined as the PO_2cri. Thus, we conclude that the higher metabolic capacity of P. simulans gives this species a better chance to survive at acutely higher temperatures in nature, although it is more vulnerable to chronic exposure.