The construction of ponds as a human intervention in nature is one of the few examples where what man did in nature was beneficial to both man and nature. Time, however, works against puddles because they are less and less needed so many are neglected. But there is energy, knowledge and the will to renew or maintain them. One of those who successfully deals with this is Alen Čikada, from KAL, an association for the protection and restoration of karst ponds, who recently gave a lecture in Sinj in Biom’s organization on the restoration of ponds, and then brought his lecture into practice and showed on the example of Marunska bunarina pond how the restoration of ponds is carried out.
Culturally and historically, ponds are present everywhere on the karst – the pond is a cultural heritage, although its original purpose is practical – the accumulation of water, says Čikada. The ponds are mostly semi-natural or artificial, they are rarely natural, and they were made by man to enable him to live on karst, that is, to be able to water the cattle.
Places for puddles were chosen by man in a way that he noticed that water was being collected in some of the depressions and decided to intervene in a way that he fenced off the depression and thus made the puddles as we see them today. At the beginning of the 20th century, new ponds stopped being built, and in the middle of the 20th century, they stopped being maintained. They are neglected, as Čikada explains, in the 1960s, when the number of cattle began to fall and there was less grazing, so water in remote places was no longer needed because cattle breeders didn’t go that far. The arrival of the water supply caused additional neglect of the ponds.
We find ponds in various places – on islands, deep on the continent, in the mountains, wherever the need arises, ponds have been built. Among them, there is an interesting pond on Silba island, placed about 15 meters from the sea, half a meter below sea level, but it is still very pure of seawater. Ponds also exist regardless of altitude, we find them everywhere, so we record a pond on Učka at 1,000 meters above sea level.
All ponds must be cleaned because leaves and soil or sludge are collected in them throughout the year, leaving less and less space for water. Rotting increases the amount of sludge and reduces the volume of water. Cleaning a puddle should therefore be a regular job, but that job is neither easy nor beautiful because the puddle neither smells nor looks nice, admits Čikada. The expert points out that people are afraid of puddles like mosquito nests. However, mosquito counts have shown that there are more mosquitoes in the proximity on one discarded truck tire full of water than around a puddle because one healthy puddle does not allow mosquitoes to breed because animals eat mosquitoes. The problem is the puddle that is overgrown with vegetation.
There are two main reasons why Čikada is embarking on the restoration of ponds: the first is the most direct one – ponds are needed if cattle breeding is to be developed in Croatia. Another reason is the biological value because the pond supports a closed ecosystem on the karst, it serves as a place where amphibians lay eggs, we can say that the pond is their “uterus”, Čikada makes an interesting metaphor.
When ponds are restored, priority should be given to those where livestock pass, or the ones in remote places where there is no other body of water nearby, so that one restored pond would support the ecosystem of the area. Čikada restores traditionally, which means that he at the start researches where is the nearest clay source, which is not lacking in the Dinaric area, in order to have easily accessible material when restoring a pond. Čikada thinks it would be good to build ponds in new places, something that is rarely done now, although new ponds can be made with little resources.
The grass is a big problem when the pond is being overgrown by it, because it loosens the soil so the water starts to be lost a lot. In cases of more gravelly soil the grass grows less, but where the soil is clean from rocks the grass grows very successfully. The root system of grass in such cases is also very widespread, creating cavities in the ground that are heated more intensively causing strong transpiration, so a lot of water is lost. In addition, the grass also uses the water for itself.
Čikada describes that when rebuilding the pond, he wants to have 30 centimeters of trampled clay on the bottom, as is the case with golf courses when building ponds. If the layer of trampled clay is 10 cm it will hold water, even such a thin layer of 2-3 centimeters of clay can hold water. It is good, however, that there is some sludge in the pond – 5 to 10 centimeters because the sludge protects the clay from the sun and drying out. At the puddle, the marginal parts start to leak first. When the puddle dries, it is good to drive a 10-ton excavator over it for a few hours as this will repair it. The pond will hold on for one season longer thanks only to that trampling. People can do the same – 20 people in boots can stamp down the clay for a few hours, advises Čikada. Previously, hay would be placed on the bottom of the pond for the cattle to eat, and then the cattle would trample the bottom of the pond even more, and some hay would remain, as well as cattle dung, which would provide an additional protective layer at the bottom of the pond. Additionally, dung enhances the ph value of the puddle.
In his lecture, Čikada also presented the main “enemies” of the pond. Gambusia affinis, he admits, disrupts the entire system, but is a minor problem. The bigger problem is the goldfish (Carassius auratus) because it reproduces excessively and has no enemies, it fertilizes the water with bodily secretions and such a pond has many more plants, which in turn create sludge. In addition, this invasive species eat indigenous animals. Another natural enemy of puddles is the red-eared slider, which is often encountered in puddles, and the problem with it is that it eats everything it catches. The golden rule is, says Čikada – “no fish should be in a puddle!”. That is why it is good for the pond to dry out, because that is how the fish disappear, while the amphibians survive.
When renovating, Čikada takes care of everything – the sludge is disposed of up to 50 meters from the pond. From this sludge all the larvae will crawl out. Aquatic plants are placed near water for 24 hours, and only then are they deposited elsewhere. When rebuilding a pond, attention is given to the amphibian season. The puddle will not be pumped out while the tadpoles are inside. Mowing around a puddle is also avoided while tadpoles become frogs. Čikada advises that it is best to clean puddles at the end of August and the whole of September and part of October. The second period of low water is February.
When intervening in the environment, man usually degrades it and reduces biodiversity. With ponds, as Čikada points out, man increases diversity because he has given water, and the environment is beautified because the ponds fit nicely into nature. Such changes nature caused by humans give added value to the environment, support the animal world in their surroundings, enable cattle grazing and are a pleasing addition to the eye. One example of the harmony of man and nature!
Watch Čikada’s lecture below (88 mins, in Croatian):