FORAMINIFERA AND MEIOFAUNA ON AN INTERTIDAL MUDFLAT, CORNWALL, ENGLAND - POPULATIONS - RESPIRATION AND SECONDARY PRODUCTION - AND ENERGY BUDGET

A rich and varied meiofauna inhabits a Cornish mudflat near the mouth of the Tamar River in southwestern England. Population densities range from 117-943 individuals .cntdot. g-1 (wet) sediment (1.4-11.4 .times. 106 individuals .cntdot. m-2), with foraminifera, harpacticoid copepods and nematodes appearing in nearly equal numbers and comprising most of the meiofauna. Seasonally, meiofaunal numbers rise and fall with solar radiation and vary inversely with river discharge. Two species, the atestate allogromiid A and the calcareous Haynesina germinica (Ehrenberg), far outnumber other foraminifera; their population densities and growth rates reach maxima in spring and summer. Monthly rates of sediment respiration are locally variable, but clearly increase from winter (4.13 ml O2 .cntdot. m-2 .cntdot. h-1 in Dec.) to spring (38.87 ml O2 .cntdot. m-2 .cntdot. h-1 in April). Experiments and calculations ascribe approximately 30% of this total to the meiofauna (including microfauna and microflora), 50% to bacteria and less than 20% to chemical oxidation. A tentative energy budget for the mudflat suggests that secondary production by meiofauna is small as compared with coastal environments elsewhere, and that meiofaunal production (426 kcal .cntdot. m-2 .cntdot. yr-1) is nearly twice meiofaunal respiration (252 kcal .cntdot. m-2 .cntdot. yr-1).