Sediment Quality in Arkansas Bait Minnow Ponds

Sediment cores were collected from 7-yr-old, 20- to 25-yr-old, and 30- to 35-yr-old ponds at a bait minnow farm at Lonoke, Arkansas, USA. Average depths of soft sediment (S and M horizons) were 8 cm in young ponds, 12 em in intermediate-age ponds, and 26 cm in old ponds. Organic carbon concentrations in sediment were low to moderate (1–2%) and carbon to nitrogen ratios were wide (20–50). Phosphorus and sulfur concentrations increased as ponds aged. Most of the phosphorus (78.9%) was in organic form, but sulfur was primarily inorganic in form (presumably iron sulfide). There appears to be two major problems associated with sediment accumulation over time. Deep, soft sediment interferes with pond management and especially with harvest. High phosphorus concentration in old sediment may contribute to dense phytoplankton blooms by supplying phosphorus to the water. Sodium nitrate treatment did not increase the rate of sediment organic matter decomposition in laboratory trials and would not be expected to enhance the degradation of sediment organic matter in ponds. The best method for improving the condition of bottoms in older bait minnow ponds probably is to remove the sediment.