A form of bacteria that can be highly toxic is present in the waters of Lake Kastoria in northern Greece, scientists say. According to experts from the Biology Department at Thessaloniki’s Aristotle University, the bacteria, which can form a harmful algal bloom on the water surface during warm weather, has existed in the lake for two decades but it is only recent DNA tests that have confirmed that this bacteria, called microcystis, produces toxins that could a pose a risk to public health. The scientists said they could not determine whether the concentration of the bacteria in the water is at a potentially risky level. They proposed the establishment of a committee of internationally recognized researchers who could assess the state of the river and contribute to efforts to tackle the problem. According to Maria Moustaka, a senior professor in Aristotle University’s biology department, one way of reducing the concentration of toxic bacteria in the water would be to introduce other «competitive» species.