Management of macrophytes in the Network's lakes

Lakes' water plants: they produce oxygen ... just like their friends from the ground!

Terlago Lake and Cei Lake are two lake basins of different depth and dimension, both present in important protected provincial areas (ex-biotype). The absence of a significant water recirculation (they don't have relevant tributaries) and supply of nutrients from the outside, have favoured a strong proliferation of water vegetation in the last years. This phenomenon characterises the natural evolution process of mountain lakes, the ecological value of which is strongly bonded to the plant and animal biodiversity living in the water. 

We have to remember that water plants or MACROPHYTES (really important for the production of oxygen in the water and as breeding and protection environment of the fish fauna) and seaweeds are not the same thing. The diffusion of seaweeds  is a threat for the vitality and liveability of many mountain lakes. 

Nevertheless the local flowering of water plants, like white and yellow water lilies (Nymphea alba e Nuphar luteum) or either the Eurasian watermilfoil (Myriophyllum spicatum), can be so numerous and invasive that in some parts it could prevent a safe bathing. 

Some approximate eradication actions have been carried out in the past in order to reduce the growing of these plants. This has indirectly contributed to their diffusion. 

With the establishment of the Network of Nature Reserves, the management of the two lakes has been sustained by serious scientific studies related to the analysis of the seabed, to the chemical composition of water and to the characterisation of vegetation. The still ongoing study, given to a group of university researchers, has allowed specific interventions aiming at the right coexistence between touristic-leisure fruition of the lake and preservation of important protected areas. 

In Lake Cei, close to the bathing beaches, the Eurasian watermilfoil has been removed (the most widespread species) with the consequently disappearance of eradicated material. 

In Lake Terlago, close to the bathing area, jute clothes have been placed on the seabed of the lake in order to prevent plants from growing and because of their biodegradability they don't need any maintenance. In addition to this experimental action of jute clothes placement, in the last years an amphibious vehicle with an underwater mowing bar and a collection basket has been used for the mowing of some sample areas. The diffusion in the lake of small pieces of plants (called propagules), generated after the mowing, has contributed to their further diffusion. 

Alongside with concrete actions, some information boards have been placed around the area in order to inform visitors. In the link below you can find some examples. 

© Rete di Riserve Bondone

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