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Venturi, Sara; Di Francesco, Silvia; Materazzi, Filippo; Manciola, Piergiorgio
doi: 10.1111/lre.12117pmid: N/A
This study examined the potential of using high‐resolution image data acquired by micro‐UAV (unmanned aerial vehicle) for analysing large‐scale environmental and hydraulic parameters. A procedure based on image data acquisition and processing is discussed and applied to a test case, Trasimeno Lake. This lake was selected for this study because of its importance in cultural, environmental and social context. This study focused on the temporal and spatial scale extension of reed beds (Common Reed). The Common Reed can strongly influence the ecological balance of the lake and particularly its evapotranspiration levels, which significantly influence the lake's water balance. Moreover, the lake provides valuable ecosystem services, including phytoremediation water treatment and the absorption of carbon (carbon sink). A presentation of the study area from a geographical and morphological perspective is provided; then, the platform (UAV and sensors) and the processing system of the images are discussed. The results concerning the accuracy of the method for the construction of georeferenced orthophotographs, and the preliminary results obtained from flights performed at different times and growing seasons of reed beds of Trasimeno Lake, are presented. This study also provides convincing evidence that the orthophotographs obtained with a low‐cost UAV system can be used to analyse changes in the extension of the Phragmites australis (Common Reed) of Trasimeno Lake, and the alteration of some environmental parameters of the vegetation, in a temporal and spatial scale. It also highlights that this system can be used to facilitate analyses performed by traditional remote sensing method.
Izmailova, Anna V.; Rumyantsev, Vladislav A.
doi: 10.1111/lre.12123pmid: N/A
The problem of lake eutrophication has been a relevant challenge for more than a century. Eutrophication has presently affected not only small‐sized and middle‐sized lakes, but most of the largest lakes in the world as well. The most rapid eutrophication has occurred for shallow water bodies in both tropical and temperate latitudinal zones. These processes are intensified by consistently high temperatures in tropical lakes, which contribute to accelerated biological processes. The eutrophication processes in deep lakes that contain large water volumes have mostly local impacts and primarily affect the shallow water zones. The dynamics of trophic status changes for the largest lakes in the world are discussed in this study, considering changes in the total water volumes characterizing different trophic categories that occurred during the period from 1950 to 2010. As the largest lakes are the most important reserves of surface fresh water on our planet, it is very important to have an understanding of the quality changes taking place in regard to this important water resource.
Cuvin‐Aralar, Maria Lourdes A.
doi: 10.1111/lre.12118pmid: N/A
Laguna de Bay is the largest inland water body in the Philippines, being used predominantly for aquaculture and open water fisheries. Aquaculture in the lake began decades ago, with many changes in the lake ecosystem having occurred since that time. Most dominant species for fish culture are introduced species. Other invasive species were also introduced to the lake as escapees from land‐based aquaculture facilities. This study was conducted to monitor fish diversity in two adjacent, but distinctly different, sites in the lake, namely an open fishery area (OFS), with no adjacent aquaculture structures, and an aquaculture site (AQS), with cages for the culture of various commodities. Fish traps were installed at both sites, with the traps being sampled at least every 2 weeks from April 2013 to February 2015. The results of pairwise t‐tests indicated significantly higher Shannon–Wiener diversity index (H′), evenness (J′), Simpson's similarity index (D) and species richness (s) in OFS than in AQS. In terms of total catch per day, significantly greater fish biomass were obtained from AQS than from OFS. Introduced aquaculture species had a mean dominance of 83% and 47% in AQS and OFS, respectively. However, invasive species introduced from the ornamental fish trade exhibited a mean relative dominance of 10.3% in AQS and 13.5% in OFS. The relative dominance of native species was also significantly higher in OFS (41%) than in AQS (6.5%). The results of this study demonstrated the adverse impacts of aquaculture in regard to the species diversity of fish in localized areas in Laguna de Bay. The dependency of aquaculture on introduced fish species adversely impacted the natural fish population in the lake. Focusing on the culture of commercially important local species for aquaculture, rather than introduced species, will improve fish production of inland waters without accompanying adverse impacts on biodiversity.
Silow, Eugene A.; Krashchuk, Lyudmila S.; Onuchin, Konstantin A.; Pislegina, Helen V.; Rusanovskaya, Olga O.; Shimaraeva, Svetlana V.
doi: 10.1111/lre.12119pmid: N/A
Plankton sampling data from the period of 1951–2010 for Lake Baikal were used in this study. Data have been collected at least monthly, generally every 7–10 days, in depth profiles from the surface to 250 m at a single offshore sampling site in the southern basin, where the water depth is approximately 800 m. Measurements of abiotic variables and phytoplankton sampling were made at discrete water depths. The data for the top 50 m of the lake were averaged for temperature and biological characteristics, noting this is the water layer in the lake exhibiting most of the lake's photosynthetic production, as well as containing the most plankton organisms. Zooplankton samples were collected with a closing plankton net and enumerated at the species level and also identified by age class. Under‐ice phytoplankton demonstrated the presence of some succession in spring phytoplankton, including a decreased proportion of endemic algal species. The open‐water complex of the alga species demonstrated that some non‐endemic species exhibited positive trends. The zooplankton analyses demonstrated a noticeable increasing trend for total zooplankton, the main zooplankton components being Epischura baicalensis, as well as increased Cladoceran numbers. These trends can be hypothetically explained by the following: (i) global climate change (although Lake Baikal also exhibits long‐term temperature oscillations); (ii) regional warming (due to construction of reservoir systems during the 1950s–1970s period); (iii) local chemical pollution attributable to increased industrial and agricultural activity in the lake's watershed and airshed basins; and/or (iv) the natural oscillating behaviour of the lake's plankton components.
Di Francesco, Silvia; Biscarini, Chiara; Montesarchio, Valeria; Manciola, Piergiorgio
doi: 10.1111/lre.12120pmid: N/A
Lakes or reservoirs are complex environmental systems, and the sustainable management of their water resources requires advanced hydrological modelling techniques of the main state parameters (water levels and volumes, temperature, pollution level, etc.) to forecast the impacts of human activities on their natural context. Bolsena Lake in northern Lazio is a typical Italian lake environment, being a source of both environmental and economic wealth for the neighbouring area, drawing tourists and providing drinking and irrigation water. The complexity of this hydrogeological and anthropogenic system, and the current technical/scientific relevance of the several water emergencies that have occurred at the lake over the past decade, highlighted the need for a solid plan to manage the possible extreme scenarios that can affect the lake basin, including mitigation of decreases in the lake levels and for controlling lake water quality and water flow rates. The objective of this study was to assess the water budget of Lake Bolsena, accounting for the various jointly involved components, in order to model the lake levels, and to examine possible future scenarios that consider both natural and anthropogenic basin factors. Hydrometeorological data are analysed for setting such scenarios. An open‐source computational model (CEQUEAU) was calibrated with the available data and then used to evaluate possible outcomes. The model simulation results demonstrated the developed hydrological model is capable of predicting water‐level fluctuations with a good accuracy for both drought and flood events, identifying it as a valuable tool for basin/lake and lake/river management and simulations.
Genseberger, Menno; Noordhuis, Ruurd; Thiange, Christophe; Boderie, Pascal
doi: 10.1111/lre.12122pmid: N/A
High suspended sediment concentrations in Lake Marken in the Netherlands result in reduced ecological values and prevent goals and standards from being met (Water Framework Directive, Natura 2000). A practical measure to improve the ecology currently being studied is the construction of sheltered areas in the north‐west part of Lake Marken. A strategy is being followed for implementation of these measures that combines in‐depth system knowledge with stakeholder aspects. This study discussed what knowledge of the underlying physical and ecological processes was needed and how it was applied, in the strategy. A coupled silt model for Lake Marken was used to study the effects of the structures on hydrodynamics, waves and sediments. The results of the silt model simulations were interpreted with in‐depth ecological expert knowledge to assess the ecological impacts of the structures. The effects of the considered sheltered areas on water transparency and wave and silt dynamics are limited, compared to the scale of the lake. These changes nevertheless provide local opportunities for ecology, and its effectiveness may be enhanced by local undeepening.
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