The rates of dry matter and nutrient loss from decomposing Potamogeton pectinatus in a brackish south-temperate coastal lake

SUMMARY. Decomposition of Potamogeton pectinatus in Swartvlei, a southern African coastal lake, followed an exponential pattern of decay. The rale constant was 0.0205 day⁻¹ and decay was virtually complete after 158 days. The original stock of ash, phosphorus and potassium was lost more rapidly than dry matter in the initial stages of decomposition due to leaching. Almost the entire stock of potassium and 60% of the phosphorus was lost in the first 7 days. The proportions of N and P in the decomposing detritus increase significantly in the final stages of decomposition, providing a rich food source for the abundant filter-feeding animals of the littoral zone. The decomposition rate of P. pectinatus is compared with that of other aquatic macrophytes and the significance of the relatively rapid decay rate of this species in the ecology of Swartvlei lake is discussed.     

Demographics of Black Vultures in North Carolina

Abstract: Understanding the contributions of vital rates to species population growth is critical to developing new management protocols. We constructed a model population for black vultures (Coragyps atratus) in North Carolina, USA, based on demographic data from a 14-year study. The model population was similar in stage structure to the reference population, and adult survival was the primary contributor to the annual rate of increase (10.6%). We suggest that the North Carolina black vulture population is experiencing high rates of survival and fertility, potentially breeding at an age younger than previously assumed, and growing rapidly.