Struttura dei popolamenti fitoplanctonici

Not availableStruttura e studio della distribuzione orizzontale dei popolamenti fitoplanctonici; Variazioni della biomassa algale; Variazioni della distribuzione spaziale dei popolamenti fitoplanctonic

Dinamica stagionale e distribuzione orizzontale di fitoplancton, carbonio organico e batterioplancton. Struttura dei popolamenti fitoplanctonici

No abstract availabl

Hypolimnetic withdrawal coupled with oxygenation as lake restoration measures : the successful case of Lake Varese (Italy)

Lake Varese is a relatively small lake, belonging to the drainage basin of lake Maggiore (northern Italy). It has had a long history (since 1960s) of water quality deterioration as the result of cultural eutrophication. In 1967 a restoration project was designed, including a sewerage network, an O-ring sewage diversion system, and a centralised wastewater treatment plant with phosphorus and nitrogen control. Since the 1990's, the lake has been the object of a cooperative research program supported by the European Commission, the Italian Ministry of the Environment, the Lombardy Region, and the Varese Province. The subsequent studies revealed that the lake responded to the decreased external nutrient loads. Besides, mathematical models predicted a rather long period (30 years) to attain the restoration goal, recognising the importance of internal P loading from sediments. Also, it was predicted that the application of in-lake measures would be beneficial in accelerating lake recovery. Recently, two measures have been suggested, i.e. hypolimnetic withdrawal in the deepest section (maximum depth: 26 m) and oxygenation in the shallower section, during summer stratification. Lake Varese constitutes the first case in Italy where in-lake methods are used to counteract the problems caused by excessive nutrient enrichment in a relative large system (lake surface: 14.52 km2). In this paper, preliminary results of the first two years of operation (2000/2001) are summarised. The results are greatly encouraging. Lake water quality characteristics are as follows: Secchi transparency increased from 3.2 m to 4.9 m; annual mean total P concentrations decreased from 180 mg/m3 to 70 mg/m3; average chlorophyll values decreased from 40 mg/m3 to 17 mg/m3; the frequency of nuisance algal blooms declined to half in comparison to the 1990's and the algal density declined by a factor of 4, and anoxia periods decreased in time and space. Moreover, it has been evaluated that nutrient loads from lake Varese, due to the selected water discharges, did not affect the total nutrient budget of lake Maggiore and the downstream water quality.El lago Varese es un lago relativamente pequeño, situado en la cuenca de drenaje del lago Maggiore (norte de Italia). Presenta una larga historia (desde los años 60) de degradación de la calidad del agua como resultado de una eutrofización cultural. En 1967 se diseñó un proyecto de restauración, incluyendo una red de alcantarillado, un sistema en anillo de desvío de aguas residuales, y una planta centralizada de tratamiento de aguas residuales con control de fósforo y nitrógeno. Desde los años 90, el lago ha sido objeto de un programa de cooperación científica financiado por la Comisión Europea, el Ministerio de Medio Ambiente de Italia, la Región de Lombardy y la provincia de Varese. Los estudios resultantes mostraron la respuesta del lago a la disminución de la carga de nutrientes externa. Además, los modelos matemáticos predijeron un período bastante largo (30 años) para lograr el objetivo de restauración, reconociendo la importancia de la carga interna de P de los sedimentos. También, se predijo que la aplicación de medidas en el propio lago sería beneficiosa en la aceleración de la recuperación del lago. Recientemente, se han propuesto dos medidas, i.e. drenaje hipolimnético en la cubeta más profunda (profundidad máxima: 26 m) y oxigenación en la zona más somera, durante la estratificación estival. El lago Varese constituye el primer caso en Italia donde se han adoptado medidas en el propio lago para contrarrestar los problemas causados por un enriquecimiento excesivo de nutrientes en un sistema relativamente grande (superficie del lago: 14.52 km2). En este artículo se resumen los resultados preliminares de los dos primeros años de actuación (2000/2001). Los resultados son enormemente alentadores. Las características de la calidad del agua del lago son las siguientes: la transparencia del Secchi aumentó de 3.2 a 4.9 m; las concentraciones medias anuales de P total disminuyeron de 180 mg/m3 a 70 mg/m3; los valores medios de clorofila disminuyeron de 40 mg/m3 a 17 mg/m3; la frecuencia de florecimiento de algas se redujo a la mitad en comparación con los años 90 y la densidad de algas se dividió por un factor de 4, y los períodos de anoxia disminuyeron en el tiempo y en el espacio. Además, se ha comprobado que la carga de nutrientes procedente del lago Varese, a causa de las descargas de agua selectivas, no afectó al balance total de nutrientes del lago Maggiore ni a la calidad del agua del río aguas abajo

Indagini limnologiche nell\u27area antistante la Foce del Torrente San Bernardino (Sopralluogo del 15 Dicembre 2009)

No abstract availabl

Indicators for the Assessment of Thresholds and Points of Non-Return

Ecological indicators are used increasingly to assess the conditions and/or status of ecosystems. Historically, the first approach was to develop indices based on a particular species or components, e.g. macrophytes, zooplankton, etc. In general, such indices are not broad enough to reflect the complexity of the ecosystem, as they do not include information at the structural, functional and system levels. To cope with these aspects new indices have been develop (for recent reviews see Rapport, 1995; Jørgensen et al., 2005) that try to synthesyze information at all ecosystem levels. In this project we are interested in evaluating indicators in terms of their potential to detect thresholds and point of non-return in coastal ecosystem.JRC.H.5-Rural, water and ecosystem resource

Indagini limnologiche nell\u27area antistante la Foce del Torrente San Bernardino (Sopralluogo del 16 Giugno 2009)

No abstract availabl

WFD and eutrophication assessment: the role of nitrogen as a driving nutrient in shaping phytoplankton assemblages in 13 Italian water bodies

This research was carried out in the frame of the LIFE project INHABIT (Local hydro-morphology, habitat and RBMPs: new measures to improve ecological quality in South European rivers and lakes). A key action of the project was finalized to detect the relationship between nutrients on the ecological quality of water bodies and to identify management options to reduce their effects on aquatic ecosystems to be included in RBMPs, focusing, in particular, on nitrogen. The outcome of the project will serve as a basis for the implementation of Water Framework Directive river basis management plans in Italy and, possibly, in Europe. Analyses were carried out on data from 13 lakes, located in two Italian Regions, Piedmont (North-western Italy, 7 lakes; 5 natural and 2 reservoirs) and Sardinia Island (6 lakes; 1 natural, 5 reservoirs). Seasonal samples were collected in each lake, from 3 to 6, depending on environmental characteristics. The following variables were considered: water temperature, conductivity, alkalinity, pH, dissolved oxygen, SRP, TP, N-NH4, N-NO3, TN, RSi, Secchi depth and chlorophyll. Species/environment relationships were explored using multivariate statistical techniques (CCA, RDA and Generalised Additive Models). Analysis was carried out on 23 phytoplankton orders and 51 genera/species. The results pointed out an increase of cyanobacteria (Nostocales and Oscillatoriales) with the increasing nitrogen availability. Moreover, a positive response of some chlorophytes species was also observed. On the other side, diatoms declined when nitrogen concentration increased. Our findings, confirming some experimental results previously obtained, emphasize the need for a further attention towards the impact of increasing nitrogen, in particular from atmospheric inputs, when restoration plans against eutrophication are designed

Studi limnologici sul bacino del Lago di Candia. Attivit? 2009

No abstract availabl