RESUMEN
This study evaluated the spatial variations in species richness and abundance of zooplankton over a hydrological cycle, and also verified the influence of physical and chemical water variables and chlorophyll-a concentrations on the abundance of these organisms. The tested hypothesis was that the zooplankton community presents higher species richness in lotic environments and higher abundance in lentic ones. One hundred forty species were identified, distributed among rotifers (88), testate amoebae (35), cladocerans (13) and copepods (4). Higher values of species richness and abundance were observed during the dry period. During both hydrological periods, the copepods presented high abundance values, due to the contribution of young stages, followed by rotifers, cladocerans and testate amoebae. In general, testate amoebae presented high values of species richness and abundance in lotic sampling stations, whereas the other zooplankton groups (rotifers, cladocerans and copepods) presented higher abundances in lentic environments and higher species richness in lotic ones. The Pearson correlation analysis evidenced the importance of physical and chemical water variables and food resource availability influencing the variation of organisms abundance.
This study evaluated the spatial variations in species richness and abundance of zooplankton over a hydrological cycle, and also verified the influence of physical and chemical water variables and chlorophyll- concentrations on the abundance of these organisms. The tested hypothesis was that the zooplankton community presents higher species richness in lotic environments and higher abundance in lentic ones. One hundred forty species were identified, distributed among rotifers (88), testate amoebae (35), cladocerans (13) and copepods (4). Higher values of species richness and abundance were observed during the dry period. During both hydrological periods, the copepods presented high abundance values, due to the contribution of young stages, followed by rotifers, cladocerans and testate amoebae. In general, testate amoebae presented high values of species richness and abundance in lotic sampling stations, whereas the other zooplankton groups (rotifers, cladocerans and copepods) presented higher abundances in lentic environments and higher species richness in lotic ones. The Pearson correlation analysis evidenced the importance of physical and chemical water variables and food resource availability influencing the variation of organisms abundance.
RESUMEN
The time constants of beat-by-beat heart rate decay for the first 30 seconds (T30) after exercise is a specific index for the vagally mediated component of heart rate recovery. The aim of our study was to determine whether cardiac rehabilitation (CR) can accelerate T30 in patients after coronary artery bypass grafting (CABG) . Thirteen male patients who underwent CABG (aged 60.5±7.7years) were assigned to 7-21 day Phase I CR. Exercise training consisted of 30 minutes of aerobic exercise (bicycle ergometer) at the anaerobic threshold 2 times per day. T30 was measured as the heart rate decay regulated in patients who rested immediately after 5 minutes of pedaling exercise. After CR, T30 significantly improved from 413.3±129.7 to 300.1±124.5 sec (p<0.01) . Peak oxygen uptake (peak V02: 14.0±4.0 16.7±3.2mlin/kg: p<0.01) and heart rate at anaerobic threshold (HR @ AT: 111.9±13.4 103.6±11.7 beatsin: p<0.01) also improved significantly. There was no correlation between ΔT30 (Δ: difference before and after CR) and Δpeak VO<SUB>2</SUB>or ΔHR @ AT. These results suggest that CR for patients following CABG accelerates vagally mediated heart rate recovery after dynamic exercise.