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Friday, May 24, 2024

History of the survival of Lake Prespa in Macedonia

The Lake Prespa basin, straddling Albania, Greece and the Republic of Macedonia, is a globally significant biodiversity gem and one of the oldest freshwater lakes in the world. More than 2,000 species of birds, fish and mammals, many unique to this region, cohabit in this fragile ecosystem.

In recent decades, however, water quality has deteriorated dramatically, leading to a depletion of fish stocks and the gradual disappearance of native species such as bleak, roach, barbel and Prespa cyprinids.

Many endangered species

In 2004, researchers sounded the alarm and documented the various sources of pollution which, combined with the effects of erosion and the massive use of the lake's waters to irrigate crops, were at the root of the deteriorating health of the lake and its wildlife.

More than 70% of the population living next to Lake Prespa in the Republic of Macedonia work in agriculture, particularly apple-growing. At the time, many farmers used large quantities of pesticides and fertilizers, which flowed into the lake. What's more, these farmers were also dumping thousands of tonnes of apples unfit for sale into the Prespa. Not to mention the untreated wastewater that joined the heaps of organic waste from farms and apple processors.

Nitrate, phosphate and nutrients from organic waste stimulate the proliferation of certain plants, in particular planktonic algae, threatening the aquatic ecosystem and even leading to the disappearance of certain species.

Nevertheless, the researchers' cries of alarm were quickly heeded by the local community. In 2004, with funding from the Swiss Agency for Development and Cooperation (SDC) and support from the United Nations Development Programme (UNDP), a project was launched to reconcile biodiversity and local development. The main aim was to protect the lake and its wildlife, while ensuring that local farmers could also prosper.

The decline of our ecosystems is not inevitable

The region's environmental challenges were daunting: wastewater collection and treatment systems had to be built, sustainable farming techniques promoted, irrigation practices transformed and forests replanted to combat erosion. Surprisingly, local communities - initially skeptical - are now almost militant partners in the Prespa ecosystem and have succeeded in reversing pollution levels, restoring an environment conducive to life.

Farming practices were transformed and farmers, after receiving specific training, opted for new methods of pest control, fertilization and irrigation. Demonstration farms were set up to test these new practices, and a program of small subsidies enabled rapid adoption.

The results are spectacular: over 80% of local farmers now opt for agro-ecological practices. Pesticide use has fallen by 30%, and harmful nutrients in the water have dropped by 60%. Phosphorus concentrations in the lake now average less than 30 μg / L, compared with 500 μg / L in samples taken in 2003.

The use of lake water for irrigation has been reduced by a factor of three. The construction of a modern composting station has made it possible to transform massive quantities of biodegradable waste, including animal waste, cuttings and apples that were ungraded or unsuitable for sale, into a high value-added product. The composting station can process up to 2,000 tonnes of organic waste per season. Not only does this reduce pollution of the lake, it also benefits farmers, who benefit from cheaper compost than artificial fertilizers.

Erosion has been halted by reforestation. A nursery has been set up to grow native saplings, and over a million trees have been planted on eroded land since 2014.






Good data are vital for good policies

One of the program's first measures was to introduce

a monitoring system to document changes in the lake's health. The absence of rigorous scientific data on Prespa Lake and its watershed, and the lack of reference points for pollution thresholds, were rightly seen as a threat to the project's success.

A state-of-the-art monitoring station was built on the edge of the lake near the town of Stenje, with a fully equipped laboratory to analyze the water samples collected regularly by a monitoring boat. Good data is vital for drawing up appropriate policies and reacting swiftly to any deterioration in ecosystem conditions.

Data from 2016 show a marked improvement in the health of the lake: phosphate and nitrate levels have been greatly reduced, oxygen concentration at the bottom of the lake has increased and native species have returned. The story of Lake Prespa shows that the decline of an ecosystem is not irreversible, and that it is possible to choose a development model that combines the benefits of sustainable development with those of the environment.