Winter and spring macroinvertebrate drift in an outpocketing of the lower Mississippi River, Louisiana (USA)

To examine temporal variations in macroinvertebrate drift in a high-order river system, surface drift was sampled each month from November 1984 to June 1985 in the lower Mississippi River. Routinely, two stations were sampled at 2-hr intervals through the night, but during January and April samples were taken every 4 hrs for a 24-hr period. Greatest drift density occurred in April, when Hydroida dominated, while lowest densities occurred in December. Drifting organisms displayed the bigeminus pattern with highest densities 4 hrs after dusk and lowest numbers one hour before sunrise.