The pond in the entrance area is again accessible to passers-by after the winter break. We talked about its spring maintenance, water quality and fish with Robert Gregorek, deputy director of the Botanical Garden of UPJŠ Košice.

What awaits us after the winter season?

Before the new season, it is necessary to clean the entire area of plantings, remove the blooming perennials, the aerial parts of which are dry, but new growths are already being born under them. We will prune some shrubs, let other species bloom and we will pay attention to them only in summer. During the winter, we left a lot of grass around the pond, for the effect with deer and frost. These have already exhausted their potential and need to be removed so that they can sprout again.

In addition to the plants we have planted, we also have vegetation that has been brought by nature. Whether it is dandelions, coltsfoot, some species of self-seeding trees, willows and poplars, we need to regulate their development a bit. We even found out that the originally living pine bore germinating seeds and new seedlings were formed. We will purposefully select what has a chance for further development.

What condition are the fish in after winter?

Almost all types of fish overwintered very well. Some of them are already in sexual maturity and will spawn this year, but most are relatively young. But, for example, the soles are already at an advanced stage of their life cycle. The possible death of individual pieces will not surprise us, it will be a natural change of generations. Young fish (koi carp, koi crucian carp, golden sturgeon, golden redfish, or natural forms of some species) are doing very well. The sturgeons are doing just as well, it is nice to see on the body profile that they have also found enough natural food. Now the time has come when the water warms up, the metabolism of the fish accelerates, and they receive supportive feed accordingly. We try not to overdo it, sometimes a smaller diet is better than overfeeding at the expense of water quality.

What is the condition of the water surface?

In the pond, aquatic plants do not yet develop any great activity. At this time, they are mostly still sleeping, we will see how they will start the season. Our goal is not to create a pond in the form of a swimming pool, but a natural habitat where even the natural opalescent haze is fine. It is important that the water is of sensory acceptable quality, that it contains enough oxygen and also offers enough natural background for the development of fish. At the moment, the support system for pumping and sludging water is also running, so the basic functions are fine.

In the spring, a natural layering of water occurs. While in winter the coldest water is near the surface (ice) and the temperature rises to 4°C towards the bottom, in summer the layering is the opposite. At the bottom, 4°C remains, but the water temperature rises towards the surface. Thanks to this natural phenomenon, the water is also relatively spontaneously cleared in the spring. We will be curious to see if there are any amphibians that would be willing to lay their eggs in the shallower parts. The surrounding vegetation has already thickened so much that it will give a chance for their overwintering.

Will you continue to monitor the impact of the water area on the microclimate in the area?

Also this year, we will record all measured values from monitoring towers, where the temperature and humidity of the air approximately 2 meters above the water surface are recorded. We also have a continuous record of temperatures under the water surface and in front of the canteen building. We will evaluate how the impact of the pond on the microclimate in the area is projected. We are also doing a similar measurement at Mlynský náhon, and we will be able to compare the industrial area, common greenery and pond with the greenery of the housing estate and the environment of an artificial watercourse of Mlynský náhon.