ABSTRACT In low-order streams, the processing of allochthonous leaf litter is essential in the carbon/energy flow dynamics. Benthic macroinvertebrates, such as chironomids, play critical roles in the breakdown of allochthonous materials, because their larvae take part in intricate trophic networks and have varied trophic ecologies. We evaluated the effects of intra-annual variability on the input of allochthonous leaf litter, and the interactions of leaf-detritus on the succession of Chironomidae assemblages in the dry, rainy, and transition seasons (rainy-dry and dry-rainy). The study took place in a stream in the Brazilian Cerrado. Leaves were incubated in the stream to ascertain the colonization process by Chironomidae and the loss of leaf litter mass after 90 days. Functional feeding groups (FFG) were less rich and less abundant in the dry and dry-rainy seasons, than in the other seasons. The FFG composition of Chironomidae demonstrated that temporal variation between seasons was affected by the exposure time of the leaf-detritus in the stream, and there was more segregation during the dry and rainy seasons. In conclusion, the colonization of leaf-detritus by Chironomidae larvae depended on how long allochthonous plant material remained in the stream, and the variability of the organic matter dynamics input into the stream.

Abstract The objective of this study was to evaluate the effect of pure glucose, glucose plus fructose, and fructose on the blood glucose of omnivorous fish tambaqui (Colossoma macropomum), Nile tilapia (Oreochromis niloticus), piau (Leporinus elongatus), and carnivorous fish hybrid Amazon catfish (Pseudoplatystoma fasciatum × Leiarius marmoratus), pacamã (Lophiosilurus alexandri), and traíra (Hoplias malabaricus). In each species, the dose 1 mL per fish with 1,000 mg kg of body weight-1 of glucose, fructose or glucose plus fructose were tested intraperitoneally. Blood glucose was measured at times 0 (control), 0.5, 1, 2, 4, 8, 16, and 24 h. The administration of 1,000 mg of glucose or glucose plus fructose per kg of live weight causes hyperglycemia in the omnivorous and carnivorous species studied. In the omnivorous species, glycemic levels were reduced from 2 to 4 h, and the regulation to baseline occurred from 4 to 8 h. In the carnivores fish, blood glucose levels declined between 1 and 8 h, and return to baseline was observed from 8 to 16 h. Tambaqui was also intolerant to high concentrations of fructose. Blood glucose levels are regulated in a shorter time in Nile tilapia (mainly), piau and pacamã.

Abstract Diet supplementation with essential oil from sweet basil Ocimum basilicum (EOOB) can increase fish growth. So, this study aimed to evaluate the effect of EOOB in the diet on growth performance and plasmatic variables of pirarucu juveniles (Arapaima gigas) submitted to stressful condition (stocking density of 7.56 kg m-3per tank and limited space). Four diets (in triplicates) were evaluated with increasing levels of EOOB (0.0 control; 0.5; 1.0; and 2.0 mL kg diet-1) over 48 days. Linalool was the major constituent of EOOB (54.19%). The addition of 2.0 mL EOOB kg diet-1 improved final weight, weight gain, specific growth rate, condition factor and feed conversion ratio; it also decreased plasma urea levels and increased plasma albumin and total proteins levels. Plasma glucose, cortisol, and acid uric levels were not influenced by the addition of EOOB to the fish diet. In conclusion, the addition of 2.0 mL EOOBkg diet-1 is recommended for pirarucu juveniles, due to improved growth performance, and this supplementation did not compromise the homeostasis of fish rearing in a high stocking density.

Abstract The objective of the present study was to evaluate growth, biochemical, hematological and intestinal enzymes responses and survival of Nile tilapia juveniles fed a diet containing the essential oil of lemongrass Cymbopogum flexuosus (EOCF) and infected by Aeromonas hydrophila. Five diets were evaluated (in quadruplicate) with increasing levels of EOCF (0.0 - control; 0.25; 0.50; 1.0 and 2.0 mL kg diet-1). On day 45, eight fish per treatment were sampled and blood, liver and intestine samples were taken. Others eight fish per treatment were infected with A. hydrophila followed by a 15-day period of observation. Citral is the main constituent of EOCF. The inclusion of 2.0 mL EOCF kg diet-1 increased specific growth rate and survival after A. hydrophila infection and decreased feed conversion ratio of Nile tilapia. In general, higher concentrations of EOCF in the diet reduced plasma glucose and triglycerides levels, and increased plasma amino acids, alanine aminotransferase (ALT) and hepatic ALT levels, hematological parameters, and the activity of intestinal enzymes. It was concluded that the inclusion of 2.0 mL EOCF kg diet-1 improved growth performance, biochemical and physiological responses and decreased mortality of Nile tilapia after A. hydrophila infection.

RESUMO Este estudo teve como objetivo analisar a diversidade e a composição da assembleia de macroinvertebrados bentônicos nas estações seca e chuvosa em um riacho do Cerrado Brasileiro, testando a hipótese que a estação seca tem maior diversidade e difere em termos de composição de organismos em relação a estação chuvosa. A coleta foi realizada em estações secas (maio e agosto/2016 e agosto/2017) e chuvosas (novembro/2016 e fevereiro e novembro/2017). Os indivíduos foram identificados em nível de família e classificados de acordo com o grupo funcional alimentar (GFA). Foram identificados 3.776 indivíduos, onde Chironomidae foi o táxon mais abundante com 2.226 organismos. O GFA com maior número de indivíduos e riqueza foram coletor-catador e predador, respectivamente. A riqueza de espécies foi maior na estação seca do que na estação chuvosa. A ordenação gerada pelo NMDS mostrou que não houve distinção na composição da assembleia entre as estações seca e chuvosa. Concluímos que variações sazonais não alteram a abundância e a composição da comunidade de macroinvertebrados bentônicos, mas a riqueza de espécies diminuiu na estação chuvosa.

ABSTRACT This study aimed to analyse the diversity and composition of benthic macroinvertebrate assemblages in the dry and rainy seasons in a Brazilian Cerrado stream, where it was hypothesized that the dry season has higher diversity and it differs in terms of organism composition in relation to the rainy season. Sampling was carried out in the dry (May and August/2016 and August/2017) and rainy seasons (November/2016 and February and November/2017). Individuals were identified at the family level and classified according to functional feeding group (FFG). There were 3,776 individuals, in which Chironomidae was the most abundant taxon with 2,226 organisms. The FFG with the highest number of individuals and species richness were collector-gatherer and predator, respectively. The species richness was higher in the dry season than in the rainy season. The ordinance generated by NMDS showed that there was no distinction in the composition of the assemblage between the dry and rainy seasons. Seasonal variations do not alter the abundance and composition of the benthic macroinvertebrate assemblage, but the species richness does decrease in rainy seasons.

Abstract: The aquatic environment presents daily and/or seasonal variations in dissolved oxygen (DO) levels. Piava faces different DO levels in the water due to its distributional characteristics. The goal of this study was to describe the effects of low DO levels on plasma ion, biochemical and oxidative variables in piava juveniles. Fish were exposed to different DO levels, including 1.0, 2.0, 3.0, 4.0 and 5.0 mg L-1 of DO for 96 h, after which blood and tissue samples (liver, kidney, gill and muscle) were collected. The decrease in DO levels decreased plasma Na+, Cl-, K+ and NH3 levels as well as protein and glycogen levels in the liver, kidney and muscle; increased Na+/K+-ATPase activity in the gills and kidney as well as glucose and ammonia levels in the liver, kidney and muscle; and increased lactate levels in the kidney and muscle. Thiobarbituric acid-reacting substances, catalase and non-protein thiol levels decreased in the tissues of piavas exposed to low DO levels. It is concluded that piava can apparently cope with hypoxic conditions; however, low DO levels are a stressor, and the tolerance of piava to hypoxia involves iono-regulatory, metabolic and oxidative adjustments.

We selected streams located in north-eastern Brazil with the objective of assessing the effect of streams of different orders (1st, 2nd, 3rd) on the distribution and composition of benthic macroinvertebrates in the rainy and dry seasons. A total of 12822 individuals and 62 taxa of benthic macroinvertebrates were obtained, of which Chironomidae was the taxon with the most individuals (60.08% of the total). The benthic macroinvertebrate assemblage ordination demonstrated that streams of the 3rd order had a different assemblage structure compared to streams of the 1st and 2nd order. This distinction may be the result of taxa substitution. The benthic macroinvertebrate assemblage structure was correlated with environmental variables. In conclusion, the variation of the environmental characteristics according to stream order was the most important factor in benthic macroinvertebrate assemblage organisation and replacement of taxa in the streams investigated.

Se seleccionaron arroyos localizados en el noreste de Brasil con el objetivo de evaluar el efecto de arroyos de diferente orden (1°, 2° y 3r) sobre la composición y la distribución de macroinvertebrados bentónicos durante las estaciones seca y lluviosa. Se obtuvo un total de 12822 individuos y 62 taxones de macroinvertebrados bentónicos, entre los cuales Chironomidae fue el taxón con mayor número de individuos. La distribución de este grupo de macroinvertebrados bentónicos demostró que los arroyos de 3r orden tienen una estructura de comunidad diferente en comparación a los arroyos de 1° y 2° orden. Esta distribución parecería ser el resultado de la sustitución de los taxones. La estructura de la comunidad de macroinvertebrados bentónicos estuvo correlacionada con las variables ambientales. En conclusión, la variación de las características ambientales de acuerdo con el orden del arroyo fue el factor más importante en la organización de la comunidad de macroinvertebrados bentónicos y la sustitución de los taxones en los arroyos investigados.

Objetivou-se com o presente trabalho avaliar o efeito de predação de inseto praga primário, Sitophilus zeamais, e secundários, Oriza ephilus surinamensis e Laemophloeus minutus em grãos de arroz armazenados. As populações foram expostas a condições controladas de temperatura e fotoperíodo (20, 25 e 30 ºC, 14 h de fotofase) em cinco diferentes densidades de infestação (10, 20, 40, 80 e 120 indivíduos). Os tratamentos foram: S. zeamais isolado; O. surinamensis isolado; L. minutus isolado; S. zeamais + O. surinamensis e; S. zeamais + L. minutus. As análises de danos dos grãos de arroz ocorreram com 7 e 14 dias após o início dos experimentos separando os insetos praga dos grãos. As maiores perdas ocorreram com o aumento de temperatura e densidade de infestação; a coexistência S. zeamais + L. minutus apresentou os maiores efeitos de predação. Conclui-se que temperaturas mais baixas e monitoramento e controle de infestação de insetos praga primários e secundários reduzem a perda de grãos de arroz armazenados.

This study aimed to evaluate the predatory effects of the primary insect pests Sitophilus zeamais and the secondary insect pests Orizaephilus surinamensis and Laemophloeus minutus in stored rice grains. The insect populations were kept under controlled conditions of temperature and photoperiod (20, 25 and 30 ºC, 14 h photophase) in five different infestation densities (0, 10, 20, 40, 80 and 120 individuals). The treatments were: S. zeamais isolated; O. surinamensis isolated; L. minutus isolated; S. zeamais + O. surinamensis and; S. zeamais + L. minutus. Analysis of rice grain damage occurred at 7 and 14 days after the beginning of the experiments, separating the insect pests from the grains. The largest losses occurred with increasing temperature and infestation density and the coexistence of S. zeamais + L. minutus produced the greatest predatory effects. It is concluded that lower temperatures as well as monitoring and control of infestation of primary and secondary insect pests reduces the loss of rice grains stored.