Seston Sedimentation in a Tropical Reservoir

ABSTRACT

Wet and dry season epilimnetic losses of particulate carbon, nitrogen, phosphorus, iron, and total suspended solids were determined for a small, mesotrophic reservoir in Lago Yure, Honduras. Measured particulate carbon, nitrogen, phosphorus, and iron losses varied between 364–1,621 mg/m²/day, 42–118 mg/m²/day, 4–16 mg/m²/day, and 54–349 mg/m²/day, respectively, depending upon allochthonous loading. Particulate carbon to nitrogen ratios in the sedimented material consistently ranged from about 9 to 11, approximating epilimnetic seston. Deposition rates of particulate phosphorus relative to concentrations in the epilimnion were quite low, indicating rapid mineralization and recycling. Phosphorus sedimentation rate coefficients (σ) calculated from both phosphorus budget and sediment trap data indicated internal phosphorus loading (5.2 mg/m²/day) only during the dry season.