Sediment accumulation, organic carbon content, and oxygen demand in commercial channel catfish (Ictalurus punctatus) ponds.

摘要

Commercial channel catfish, Ictalurus punctatus, production conducted in earthen ponds, is the most important aquaculture industry in the United States. Erosion of pond embankments leads to sedimentation and a progressive reduction of pond depth that complicates fish harvest. Additionally, sediment is a major sink for dissolved oxygen (DO) in catfish ponds. The objectives of the study were to define sediment accumulation, organic carbon content and oxygen demand in commercial catfish ponds.; Sampling was conducted from April to September in 1998 and 1999 in 45 commercial catfish levee-type ponds located in west-central Mississippi. Sediment depth (n = 15 for each pond) ranged from 0.5 to 95 cm in ponds ranging from 14 d to 21 y of continuous use, with predicted accumulation of 12.5 cm after one year. Sediment accumulated with pond age but at a decreasing rate with time. Organic carbon concentration in the upper 2 cm of sediment ranged from 0.76 to 2.89% with a mean of 1.75%. Despite large amounts of organic matter from feed and primary production, organic carbon concentration remained appreciably unchanged with age.; Sediment oxygen demand (SOD) determined by in situ respirometry (n = 167) ranged from 63 to 1038 mg m−2 h−1 , with an average of 359 mg m−2 h−1 . Multiple regression models to predict SOD (n = 65) were constructed using 9 corollary chamber variables. Seven models had support when tested by Akaike's Information Criterion (AIC). Corollary chamber model variables included in each of the supported models to estimate SOD were dissolved oxygen concentration in the overlying water, particulate organic matter concentration just above the sediment, and organic carbon concentration in the upper (2 cm) sediment layer. The seven models indicated as having support were used with the corollary variables in a Monte-Carlo simulation to predict an industry average SOD of 470 mg m−2 h−1.; Based on measured pond water respiration of 1.0 mg l−1 h−1 and published values for channel catfish respiration, SOD accounted for 10 to 48% of total pond respiration, and was inversely related to water depth. Results of the simulation suggested that ponds constructed with a water depth of 1.50 to 1.75 m would maintain adequate DO concentration for fish growth and survival and minimize costs associated with aeration.