Since the first World Earth Day celebration in the United States in 1970, it has been celebrated every year on this day, April 22nd, as a reminder of environmental protection, restoration of damaged ecosystems and more sustainable life. It was not until 2009 that the United Nations officially designated April 22nd as International Mother Earth Day. According to the UN, International Mother Earth Day is celebrated as a reminder that the Earth and its ecosystems provide us with life and survival. As the Declaration states, the healthier our ecosystems are, the healthier the planet and its people are. “Restoring our damaged ecosystems will help us end poverty, fight climate change more successfully and prevent mass extinction. But, we will only succeed if everyone does their part,” the UN said.

If we stick to the maxim “Think globally, act locally”, nothing fits better into the mission of celebrating this day than the mission of our  Ecolacus project – Biodiversity and Water Protection Lake Palic and Lake Ludas, where various companies, the local government of Subotica and the investor did just that – they played their role and enabled changes for the better.

The Ecolacus project has been prepared for a long time, the implementation of which is the real example of excellent cooperation between the City Administration of the City of Subotica and several public companies – PUC Vodovod i kanalizacija, PE Palic-Ludas and the company Park Palic doo.

The wildlife in and around the lake has become a vicious circle over the decades, in which the quality of the water body has been deteriorating year after year. Many plant and animal species have become endangered to the extent that something urgent has to be done. The received grant from the German development bank KfW was the turning point.

The situation was very unsatisfactory at the beginning of the project. Lake water quality data, which the Public Health Institute of Subotica regularly monitors, showed that lake pollution values dropped after the commissioning of a modern wastewater treatment plant (WWTP) in Subotica. WWTP is designed to remove nutrients, which means that not only carbon substances (COD and BOD5) are removed, but also nitrogen (N) and phosphorus (P). Both elements must be present in high concentrations in water for eutrophication to occur. High N and P levels enable excessive growth of algae, which leads to the algal bloom (blue or red lake colour).

High biological activity consumes free oxygen in the water, causing high turbidity (reduced transparency), which eventually leads to mass fish kill. Only certain fish species can survive in such an environment leading to a biodiversity reduction and one fish species dominance. For that reason, the number of silver carp (usually known as “babushka”), which is not a native (indigenous) species in these lakes, has increased extensively.

Experts estimate that the fish biomass of Lake Palic is about 150 tons, with a healthy population of less than half of that. An experimental fishing campaign conducted in 2016 showed that more than 90 per cent of them are babushkas.

Nevertheless, there were many more babushkas than the experts assumed. The exceptionally successful selective fishing campaigns of babushka from the beginning of the project until this February resulted in over 200 tons of catch of this fish species only.

Additionally, various measures have been implemented, such as the sewage construction and connecting households around the lake to it, upgrading of the Wastewater Treatment Plant and pumping station, establishing a buffer zone around the lakes and planting certain plant species. A newly built bicycle path, bird watching towers and rest areas for visitors raised the tourist potential of the beautiful Subotica Palic and Ludas lakes to a higher level.

The initial 6.5 million Euros (about 780 million dinars) for this project implementation are grants from the Government of Germany, managed by KfW – German Development Bank, after which another 1.3 million Euros (approximately 153 million dinars) were provided.

One million Euros (about 120 million dinars) were provided by the local government (City of Subotica) for the land acquisition, compensation payments, as well as contributions in kind.

All these investments are already showing positive effects on water quality and the biodiversity of plant and animal populations in this area.

To have the full effect of the implemented measures, we all must further maintain and care about everything achieved in the project even after the formal completion of all project activities at the end of this year.

Since a long period is required to change the water body such as the lake, and since it takes years for the plants to fully develop the beneficial effects of all the above measures on Lake Palic water quality will be fully visible and measurable only after several years.

Until then, we hope to celebrate every next Earth Day with even more positive news from the Subotica lakes.