The metabolic cost of nesting: body condition and blood parameters of Caiman crocodilus and Melanosuchus niger in Central Amazonia

Although nesting ecology is well studied in several crocodilian species, it is not known how nest attendance influences physiology and body condition of nesting females. In this study, we describe body condition and serum biochemical values of nesting female, non-nesting female and male spectacled caiman (Caiman crocodilus) and black caiman (Melanosuchus niger) in two areas of Central Amazonia. We also evaluated the effect of nest age and nest distance to water on body condition and blood parameters of nesting females. Body condition and plasmatic concentrations of glucose, triglycerides, lactate and uric acid of nesting females were significantly different from those of non-nesting females and males in C. crocodilus, but not in M. niger. Our study also demonstrated that nest age and distance to water had a negative effect on female body condition in C. crocodilus, but not in M. niger. Female C. crocodilus attending older nests or nests built further away from permanent water bodies tended to have lower body condition. Our results demonstrate that the nesting strategy of C. crocodilus has a metabolic cost associated with nest attendance for nesting females, which appear to depend on accumulated energetic reserves during nest attendance. In contrast, nest attendance had little effect on the physiology of female M. niger. © 2017, The Author(s)

André DUNES, Documentation juridique, Paris, Dalloz, Coll. « Méthodes du droit », 1977, 198 pp., 46FF

Poor water quality condition has been pointed out as one of the major causes for the high mortality of ornamental fishes exported from the state of Amazonas, Brazil. The purpose of the current study was to define water quality standards for cardinal tetra (Paracheirodon axelrodi), by establishing the lower and higher for lethal temperature (LT50), lethal concentration (LC50) for total ammonia and nitrite and LC50 for acid and alkaline pH. According to the findings, cardinal tetra is rather tolerant to high temperature (33.3 ºC), to a wide pH range (acid pH=2.9 and alkaline pH=8.8) and to high total ammonia concentration (23.7 mg/L). However, temperatures below 19.6 ºC and nitrite concentrations above 1.1 mg/L NO2- may compromise fish survival especially during long shipment abroad.A má qualidade da água tem sido apontada como uma das maiores causas da alta mortalidade dos peixes ornamentais exportados pelo Estado do Amazonas, Brasil. A proposta deste estudo foi definir padrões de qualidade da água para o cardinal tetra (Paracheirodon axelrodi), estabelecendo a menor e a maior temperatura letal (LT50), a concentração letal (LC50) para amônia total e nitrito e LC50 para pH ácido e alcalino. De acordo com os resultados, o cardinal tetra é mais tolerante a temperaturas elevadas (33,3 ºC), a amplos limites de pH (pH ácido = 2,9 e pH alcalino = 8,8) e a alta concentração de amônia (23,7 mg/L). Entretanto, temperaturas abaixo de 19,6 ºC e concentrações de nitrito acima de 1,1 mg/L NO2- podem comprometer a sobrevivência dos peixes, especialmente durante longos períodos de transporte para o exterior

Body color pattern and aggressiveness related to behavioral context and light intensity in an Amazonian cichlid, Laetacara fulvipinnis Staeck & Schindler, 2007

The aim of this study was to describe agonistic interaction and color patterns relative to social status and to evaluate the effects of light on aggressiveness in Laetacara fulvipinnis. Eight agonistic events were observed: frontal display, mouth fight, nipping, chase, parallel display, threat, undulation, and flight. Four body color patterns were related to the social context. Two light levels were also tested: groups of juveniles were maintained for 15 days under low (228 ± 38.60 lx) or high (1435.92 ± 481.40 lx) light. Color pattern a was mainly observed during escalating agonistic interactions. Other patterns were exhibited during flight, rest, and attack. High light decreased the latency to fighting; increased the frequency of threats, total attacks, and flight; and destabilized the social hierarchy. These findings indicate that light intensity increases aggressiveness, interferes with the stability of hierarchies, and may result in a stressful situation with negative effects on animal welfare. © 2017 Informa UK Limited, trading as Taylor & Francis Group

Hypoxia Tolerance of Amazon Fish: Respirometry and Energy Metabolism of the cichlid Astronotus ocellatus

As a result of regular flood pulses, the Amazon basin exhibits large annual changes in its chemical and physical parameters. Ecology and distribution of fish communities seem to be directed by seasonal and diurnal oxygen level oscillations. Amazon fish have developed strategies to thrive under these varying conditions. Astronotus ocellatus normally survives large fluctuations in oxygen availability in varzea lakes. Respirometric and metabolic changes in A. ocellatus were studied during exposure to stepwise declining oxygen levels. Respiration rates were continuously recorded. Haematologic and metabolic parameters (lactate, glucose, cortisol and free fatty acids (FFA)) were determined. A. ocellatus was found to be hypoxia tolerant; it survives more than 16 h of severe hypoxia (pO2 ≤ 0.4 mg l- 1) and even 4 h of complete anoxia at 28°C. Its routine metabolic rate is 10.8 mg O2 h-1 per 100 g fresh weight. A significant decrease in standard metabolic rate (SMR) starts at 20% air saturation, whereas a significant change of blood lactate does not start until 6% air saturation in water. We suggest therefore that A. ocellatus responses to environmental hypoxia are based mainly on suppressed metabolic rate, whereas under deep hypoxia or anoxia partial compensation is obtained from anaerobic glycolysis