Abstract
One of the most important goals of EU nature and water framework directives is to ensure healthy aquatic ecosystems by the protection of the most valuable species and habitats form the Natura 2000 network, while at the same time ensuring a balance between water/nature protection and the sustainable use of nature’s natural resources. The purpose of this study was to evaluate the physico-chemical and microbiological characteristics of four Romanian salty plain lakes included in Natura 2000 Network, in order to assess the degree of organic pollution and to generate the knowledge required for the design and implementation of appropriate measures for maintaining the balance between the water protection and the sustainable use of these protected ecosystems. The water and sediment sampling was performed in two consecutive years (2015 and 2016), in September and the following standard parameters have been determined: pH, chemical oxygen consumption (COC), the degree of trophicity and salinity of the environment, metals content, microbiological indicators and microbial physiological groups involved in nutrient cycling. The pH ranged from 7.56 to 8.93, close or above the upper normal limit of 8.5, being correlated with a high salinity characteristic of chlorinated, sulphated, high sodium and magnesium content waters. Despite the similar values recorded for the physico-chemical parameters in the two consecutive years suggesting a certain degree of stability of the investigated aquatic ecosystems, the COC values indicate a high degree of hypertrophy, which could be attributed to the reduced surface area, ecological pisciculture and agriculture input. The microbiological parameters revealed the existence of both recent and chronic fecal pollution source. The high hypertrophy degree could represent a positive premise for the high productivity of the investigated ecosystems, but also an alarm signal for excessive organic pollution, with the risk of redox potential decrease which can affect the fish and other life forms. Consequently, it is necessary to identify the sources of pollution and implement the appropriate measures to minimize the negative impact of organic contamination on the status of the respective ecosystems (water quality, biotic components) in order to maintain the health of both ecosystems and the surrounding human communities, allowing at the same time a sustainable use of the local resources.
Highlights
The protection of Europe’s most valuable species and habitats form the Natura 2000 network is regulated by many EU incentives, such as “Birds”, “Habitats” and “Water Framework” Directives, EU’s biodiversity policy etc., which aim to provide some of the main tools required for bringing protected species and habitats into a favorable conservation status, ensuring both healthy aquatic ecosystems and a balance between water/nature protection and the sustainable use of nature’s natural resources
The purpose of this study was to evaluate the physico-chemical and microbiological characteristics of four Romanian salty plain lakes included in Natura 2000 Network, in order to assess the degree of organic pollution and to generate the knowledge required for the design and implementation of appropriate measures for maintaining the balance between the water protection and the sustainable use of these protected ecosystems
Despite the similar values recorded for the physico-chemical parameters in the two consecutive years suggesting a certain degree of stability of the investigated aquatic ecosystems, the chemical oxygen consumption (COC) values indicate a high degree of hypertrophy, which could be attributed
Summary
The protection of Europe’s most valuable species and habitats form the Natura 2000 network is regulated by many EU incentives, such as “Birds”, “Habitats” and “Water Framework” Directives, EU’s biodiversity policy etc., which aim to provide some of the main tools required for bringing protected species and habitats into a favorable conservation status (to prevent the deterioration of any status), ensuring both healthy aquatic ecosystems (good ecological potential and good chemical status in artificial and heavily modified water bodies) and a balance between water/nature protection and the sustainable use of nature’s natural resources. Lake waters pollution can be physical (soil particles eroded from landscape or washed by flowing water, heat discharged from an industrial source or from runoff from hot surfaces in warm weather or cooling waters), chemical (including major inorganic elements dissolved from soil and rocks or from plants, as well as organic compounds from decaying materials and discharged from human-made urban, agricultural or industrial environments) and biological (non-native plants and animals, overabundance or selective growth of some native species etc.) [3] [4]. The microorganisms remineralize the organic matter to carbon dioxide, water, and various inorganic salts both in aquatic and terrestrial ecosystems. Many substances, such as lignin, cellulose, chitin, pectin, agar, V. Aquatic sediments represent a distinct ecological zone characterized by a low redox potential and a microstratification of physico-chemical factors that facilitate the occurrence of specific ecological niches, favoring the excessive growth of heterotrophic bacteria, and of microaerophilic and strictly anaerobic species
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