Length-specific carbon content of the Daphnia population in a large subalpine lake, Lago Maggiore (Northern Italy): The importance of seasonality

1997 ◽  
Vol 59 (1) ◽  
pp. 48-56 ◽  
Author(s):  
Marina Manca ◽  
Patrizia Comoli ◽  
Teresa Spagnuolo
Keyword(s):  
Carbon Content ◽  
Northern Italy ◽  
Subalpine Lake ◽  
Daphnia Population

Modeling the hydrodynamics of a wetland under strong anthropic pressures (Torbiere del Sebino, Italy)

2021 ◽  
Author(s):  
Stella Volpini ◽  
Marco Pilotti ◽  
Giulia Valerio ◽  
Steven C. Chapra
Keyword(s):  
Water Quality ◽  
Specific Conductivity ◽  
Quantitative Information ◽  
Northern Italy ◽  
The South ◽  
The North ◽  
Subalpine Lake ◽  
Ecological Importance ◽  
Set Up ◽  
And Shifts

<p>The Natural Reserve “Torbiere del Sebino” is situated on the southern bank of Lake Iseo and is one the most meaningful wet zone for extension and ecological importance of northern Italy, belonging to the Natura2000 network.</p><p>Torbiere occupies an area of 3.60 km<sup>2</sup> within a 14 km<sup>2</sup> watershed where almost 12000 inhabitants live and where agricultural activities, mostly vineyards, cover almost 40% of the area; this leads to a significant anthropic pressure that over the last 50 years has compromised the system and changed the equilibria between species, enhancing eutrophication.</p><p>Despite the ecological relevance of the area, one of the most important in northern Italy, very little quantitative information is available regarding its current state and evolution in terms of water quality and hydrodynamics.  Given the critical environmental condition of the habitat, it is necessary to address the consequences of human impact on the trophic state of Torbiere.</p><p>Torbiere consists of a system of shallow lakes or ponds (average depth 1.5 m) whose main affluent is a creek (called Rì) entering from the South. A secondary occasional affluent enters the system from the East and consists of a combined sewer overflow (CSO). Finally, the main effluent is an artificial channel located in the North connecting Torbiere directly with the subalpine Lake Iseo. Although originally subdivided into a set of many interconnected ponds, the separation levees have been demolished over the last decades to enhance internal circulation, under the assumption that this would decrease the residence time and improve the water quality. However, no rational argument was used to support this decision that led to a system where similar characteristics (Secchi’s depth, turbidity, specific conductivity) are found all over the study area and where the expansion of invasive species was easier; now there is some evidence that a separate set of ponds would be better manageable to contrast the eutrophication process. To understand this process, a 3D hydrodynamic model has been set up using Delft-3D, an open source, finite difference package. </p><p>Given the great extension of the system, the inner circulation of the water is not driven by the momentum of the affluents, instead the wind plays a major role. This forcing term presents a daily pattern: it blows from the North in the mornings and shifts to the opposite direction in the late afternoon. The water mainly flows from the South to the North. However, preliminary results by Delft 3D showed that the circulation is made complex by the wind. The model shows that opposite directions of horizontal flow velocities are found at the surface and at the bottom of the water column, showing that only the upper layers follow the direction of the wind.</p><p>By comparing the actual and previous conditions of separation of the ponds, the model aims to give an answer to whether the choice of demolishing the banks was positive or negative for the water quality of Torbiere. Once the role of the banks will be clarified, the effects of their possible restoration will be addressed.</p>

scholarly journals Trophic Magnification of Legacy (PCB, DDT and Hg) and Emerging Pollutants (PFAS) in the Fish Community of a Small Protected Southern Alpine Lake (Lake Mergozzo, Northern Italy)

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1591 ◽  
Author(s):  
Michela Mazzoni ◽  
Claudia Ferrario ◽  
Roberta Bettinetti ◽  
Roberta Piscia ◽  
Davide Cicala ◽  
...  
Keyword(s):  
Fish Community ◽  
Northern Italy ◽  
Emerging Pollutants ◽  
Trophic Levels ◽  
Perfluoroalkyl Acids ◽  
Trophic Chain ◽  
Magnification Factors ◽  
Subalpine Lake ◽  
Wet Weight ◽  
Cold Lake

The biomagnification of mercury, polychlorobiphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs) and perfluoroalkyl acids substances (PFASs) was evaluated in the trophic web of Lake Mergozzo, a small and deep Italian subalpine lake, which has been chosen because it is a protected environment, and discharges into the lake are mostly avoided. Carbon source and relative trophic levels were calculated by using 13C and 15N stable isotopes, respectively, and trophic magnification factors (TMFs) were derived. Zooplankton and thirteen species of fish were collected and analyzed, and the results showed the elevated level of biota contamination from both legacy and emerging pollutants, even if direct discharges were avoided. Concentrations in biota, expressed as sums of compounds, ranged from 0.4 to 60 µg kg−1 wet weight (ww) for PFASs, from 16 to 1.3 104 µg kg−1 lipid content (lw) for DDTs, from 17 to 1.5 104 µg kg−1 lw for PCBs and from 20.0 to 501 µg kg−1 ww for mercury (Hg). TMFs of this deep, cold lake, with a prevalent pelagic trophic chain, were high and clearly indicated fish biomagnification, except for PFAS. The biomagnification capability of PFAS in a fish-only food web was discussed by using the biomagnification of Hg as a benchmark for assessing their bioaccumulation potential.

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