ON THE SPATIAL-DISTRIBUTION AND RESPIRATORY ENVIRONMENT OF BENTHIC MACROINVERTEBRATES IN PONDS

The influence of oxygen distribution in a shallow water on the spatial distribution of the macrobenthic fauna has been investigated. We stud ied both the bathymetric and the vertical distribution in the sediment in order to assess the biological importance of oxygen microstratific ation. Oxygen concentrations in the water column were measured with a Clark Au-Ag electrode (WTW EO 196). Oxygen concentrations at the sedim ent-water interface and in the sediment were measured directly in core samples with Clark-style micro-electrodes (Diamond 737GC). Our result s indicate that the composition of the macrobenthic community is well correlated with the bathymetric distribution of oxygen in the water co lumn. However, some burrowing chironomid species appear to be dependen t on the oxygen at the sediment-water interface. Our conclusion is tha t the respiratory environment of benthic animals (cf. Brundin, 1951) i s broader than expected, very specific, and linked to their vertical d istribution in the sediment.