The spatial variation of oxygen condition in carp pond located in nature reserve ?Stawy Milickie” / Przestrzenne zró?nicowanie warunków tlenowych w stawie karpiowym po?o?onym w rezerwacie przyrody ?Stawy Milickie”

摘要

The paper presents the results of research on the spatial variation of oxygen condition in a carp pond. The analysis of dissolved oxygen was carried out in the summer in 29 measuring points. In the analysed months the differences were determined between dissolved oxygen concentration in the strip of rushes and the part of the pond free from macrophytes. In the strip of rushes, the average concentration of dissolved oxygen was between 4.69-6.49 mg O2?·dm-3. In the part of pond located near the strip of rushes the oxygen concentration was between 6.23-7.91 mg O2?·dm-3 and in open water concentration of dissolved oxygen was in range 7.60-9.09 mg O2?·dm-3. It was found that the biggest differences in oxygen concentration occur between the strip of rushes and the open water column: 40% in June, 26% in July, 28% in August, 38% in September, respectively. In the south-western part of the pond, covered with macrophytes and shaded by trees, the worst oxygen conditions were observed - below the optimum level for carps, sometimes reaching lethal values. The best oxygen conditions, noted in July and August, were in the central and northern part of the pond including the fishery and feeding point. In order to improve the oxygen conditions in macrophytes zone it is recommended to remove the rushes periodically and to remember to leave the part of emergent plants that are necessary for breeding and living avifauna. The scope and timing of the removal of plants has to be consulted and co-ordinated with the Regional Conservator of Nature.