Abstract
AIM: This study evaluated the body condition de Acestrorhynchus pantaneiro, Auchenipterus osteomystax, Pimelodus maculatus, Psectrogaster curviventris and Schizodon borellii in the Manso reservoir, Mato Grosso State, Brazil, during the first years after its formation (years I, II, III and IV). We hypothesized that sudden environmental changes alter differently the body condition, according to the time (sampling years) and sex of individuals. Also, we checked the influence of the amount of food ingested and the reproductive status on nutritional status of the species. METHODS: The body condition (Kn), the feeding activity (SRI) and reproductive (GSI) were calculated only for adults. The difference between the sampling years and sexes (used as factors) was assessed using the nonparametric Kruskal-Wallis test. Temporal influence was tested by Spearman correlation and the interaction between both factors by PERMANOVA. RESULTS: The values of the Kn showed two groups: group 1: species whose body condition decreased in the year II, with a posterior increase (A. pantaneiro, P. curviventris and S. borelli), considered sensitive to the reservoir filling; group 2: species whose body condition increased in the year II (A. osteomystax and P. maculatus), indicating a more rapid adaptation to new environmental conditions. Still, all parameters investigated were somehow affected by the dam, mainly the body condition and gonadosomatic index for several species. On the other hand, the least affected factor was the feeding activity. CONCLUSIONS: The results did not evidence a same pattern of either increase or decrease of body condition for all species examined, since everything indicates that responses are species-specific. Even with a lack of consistency in some results, we can draw some suggestions for future investigations. Responses to these questions will certainly contribute to aggregate data to help better explain the body condition of fish species in dammed environments.
Highlights
IntroductionThe nutritional status reflects the health or overall welfare of an animal and is usually associated with physiological parameters related to energy storage in tissues, in the form of carbohydrates, lipids and proteins (Le Cren, 1951).The energy stored can be measured by diverse criteria that include physiological (weight of liver and gonads), biochemical (lipid or protein content) and morphometric (weight-length) measurements (Lloret et al, 2002)
The nutritional status reflects the health or overall welfare of an animal and is usually associated with physiological parameters related to energy storage in tissues, in the form of carbohydrates, lipids and proteins (Le Cren, 1951).The energy stored can be measured by diverse criteria that include physiological, biochemical and morphometric measurements (Lloret et al, 2002)
Fish begin to allocate part of the energy to be invested in the maintenance, growth and reproduction to minimize the effects of changing environmental conditions (Wootton, 1998), thereby compromising their nutritional status
Summary
The nutritional status reflects the health or overall welfare of an animal and is usually associated with physiological parameters related to energy storage in tissues, in the form of carbohydrates, lipids and proteins (Le Cren, 1951).The energy stored can be measured by diverse criteria that include physiological (weight of liver and gonads), biochemical (lipid or protein content) and morphometric (weight-length) measurements (Lloret et al, 2002). The nutritional status of the fish can be influenced by abiotic (Oliva-Paterna et al, 2003; Bojsen, 2005; Araújo et al, 2011) and biotic factors (Lima-Junior and Goitein, 2004; Felizardo et al, 2011). In this way, to survive and leave offspring in active systems such as rivers, fish populations face many challenges and respond to changes in the environment with changes in their metabolism. Fish begin to allocate part of the energy to be invested in the maintenance, growth and reproduction to minimize the effects of changing environmental conditions (Wootton, 1998), thereby compromising their nutritional status
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