Meiobenthos and the oxygen budget of an intertidal sand beach

Field and laboratory experiments are used to construct a partial oxygen budget for a typical fine sand area just above mean tide level in Strangford Lough, Northern Ireland. Oxygen consumption was determined mainly from batch respiration using a YSI electrode. Experiments with different batch sizes indicate that oxygen uptake rate per individual decreased as the number in the test chamber increased. Experiments conducted monthly at ambient environmental temperature with batches of 40 individuals show minimum oxygen consumption occurred at 12 °C in the nematode, copepod and turbellarian populations tested.Modelling the situation for 1 m² of beach in November 1979 gives a meiofaunal demand from 295,250 individuals of a total 40 ml O₂ . h^–1 compared with an estimated 2760 for macrofauna and 1172 for sediment with attached microorganisms. Microfloral production was calculated as 324 ml O₂ . h^–1 in light. The individual meiofaunal respiration values are much higher than those previously reported. The reasons for this and the confidence which can be attached to these and other workers results are discussed. Information from laboratory and field results is used to construct a partial oxygen budget for a typical fine sand area just above mid-tide level in Strangford Lough, Northern Ireland. Oxygen consumption by meiofaunal taxa and Hydrobia was determined from batch respiration experiments using a YSI oxygen electrode, as was consumption and production by sediment with attached microflora. Experiments conducted monthly at ambient temperature indicate minimum oxygen consumption at 12 ° C in the nematode, copepod and turbellarian (Monocelopsis sp.) population tested. Batch size affected consumption; with nematodes, copepods and gastrotrichs (Turbanella varians) uptake per individual decreased as number in the test chamber increased. Later experiments were therefore conducted with a standard batch size of 40 individuals.Inspection of biological and physical data showed conditions in November 1979 were close to the annual mean. Using these and the appropriate laboratory data the calculated values give a meiofaunal oxygen demand per m² of beach of 40 ml h^–1 compared with an estimated 2760 for the macrofauna and 1172 for the sediment with attached micro-organisms. Microfloral oxygen production was 324 ml h^–1 in light. The meiofaunal figures are based on a population of 295,250 individuals per m² with a percentage composition of Nematoda 58.2, Copepoda 22.7, Gastrotricha 14.4, Turbellaria 5.3 and Gnasthostomulida 1.3. These figures give a relative population oxygen uptake of 50.1 : 32.3 : 5.1 : 9.9 : 2.7% respectively. The confidence which can be attached to these and other workers results is discussed.