Browsing by Author "Favaro, Luis Fernando"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- Age and growth of Zapteryx brevirostris (Elasmobranchii: Rhinobatidae) in southern BrazilPublication . Carmo, Wanessa P. D.; Favaro, Luis Fernando; Coelho, RuiAge and growth studies are fundamental to successful fisheries management. Zapteryx brevirostris (Muller & Henle, 1841) is distributed off the Brazilian continental shelf and this species is assessed as "Vulnerable" in the Red List of the International Union for the Conservation of Nature (IUCN). Thus, the objective of this study was to present previously unknown information about the age and growth of Z. brevirostris that can be used for its management, conservation, and fisheries. A total of 162 specimens were sampled, with total lengths (TL) varying between 35.7 cm and 56 cm. The vertebrae were embedded in resin, sectioned in cuts with 0.5 mm thickness and the growth bands of the vertebrae were read under a light microscope. In the studied area, Z. brevirostris ages were estimated from 4 to 10 years according to vertebrae patterns. The species reaches its maximum asymptotic size (Linf) around 56 cm (56 cm for females and 50.37 cm for males). This is the first estimate of age and growth for a species of the Zapteryx genus, and the results support the hypothesis that this ray requires future management conservation, particularly due to its slow growth rate and consequent susceptibility to overexploitation.
- Effect of long-term thermal challenge on the Antarctic notothenioid Notothenia rossiiPublication . Kandalski, Priscila Krebsbach; Zaleski, Tania; Forgati, Mariana; Baduy, Flávia; Eugenio, Danilo Santos; Machado, Cintia; Dmengeon Pedreiro de Souza, Maria Rosa; Piechnik, Claudio Adriano; Favaro, Luis Fernando; Donatti, LuceliaThe thermal stability of the Antarctic Ocean raises questions concerning the metabolic plasticity of Antarctic notothenioids to changes in the environmental temperature. In this study, Notothenia rossii survived 90 days at 8 degrees C, and their condition factor level was maintained. However, their hepatosomatic (0.29x) index decreased, indicating a decrease in nutrient storage as a result of changes in the energy demands to support survival. At 8 degrees C, the plasma calcium, magnesium, cholesterol, and triglyceride concentrations decreased, whereas the glucose (1.91x) and albumin (1.26x) concentrations increased. The main energy substrate of the fish changed from lipids to glucose due to a marked increase in lactate dehydrogenase activity, as demonstrated by an increase in anaerobic metabolism. Moreover, malate dehydrogenase activity increased in all tissues, suggesting that fish acclimated at 8 degrees C exhibit enhanced gluconeogenesis. The aerobic demand increased only in the liver due to an increase (2.23x) in citrate synthase activity. Decreases in the activities of superoxide dismutase, catalase, and glutathione-Stransferase to levels that are most likely sufficient at 8 degrees C were observed, establishing a new physiological activity range for antioxidant defense. Our findings indicate that N. rossii has some compensatory mechanisms that enabled its long-term survival at 8 degrees C.