Search results for " lake"

Using invertebrate remains and pigments in the sediment to infer changes in trophic structure after fish introduction in Lake Fogo: a crater lake in …

2010

Importance of water-level fluctuation on population dynamics of cladocerans in a hypertrophic reservoir (Lake Arancio, south-west Sicily, Italy)

1997

During a period of three years (1990-1991 and 1993), we studied the population dynamics of planktonic cladocerans in a hypertrophic reservoir. Weekly sampling revealed that the five most common species followed a trend which reflects the peculiar hydrological characteristics of the reservoir and their key position in the pelagic food web. In particular, 1991 was characterized by a strong water inflow which probably interfered with the reproductive activities of the dominant fish population (Rutilus rubilio) and reduced the concentration of inedible planktonic algae allowing the development of small Chlorococcales. This event was associated with higher population densities of Daphnia hyalina…

Genetic-based evaluation of management units for sustainable vendace (Coregonus albula) fisheries in a large lake system

2022

The goal of the processing industry, trade and consumers is to get eco-labelled freshwater fish products from sustainable fisheries into the market as soon as possible. The fourth largest natural lake system in Europe, the Saimaa lake system supports a fishery for vendace (Coregonus albula). Certification of the fishery requires an understanding of population structure to help determine the number and spatial extent of management units. In this study, we analysed the genetic diversity of local vendace populations in the Saimaa lake system and aimed to identify the conservation and management units of vendace. Within the Saimaa, the genetic divergence between local populations of vendace was…

Jets interacting with vegetation in the rotating LEGI platform

2019

Rivers and wastewater discharges flowing into lakes and coastal waters strongly affect aquatic ecosystems, based on their transport of turbulence, tracers and sediment particles. Mixing and spreading of outflows have an even greater impact when the receiving site is obstructed by vegetation canopies or mussel cultivation farms. Thus, a thorough knowledge of the interaction between effluents and receiving bodies is required to mitigate impacts and promote best environmental management practices, also following the 2015 EU Marine Strategy Framework Directive.

Whole-lake experiments reveal the fate of terrestrial particulate organic carbon in benthic food webs of shallow lakes

2014

Lake ecosystems are strongly linked to their terrestrial surroundings by material and energy fluxes across ecosystem boundaries. However, the contribution of terrestrial particulate organic carbon (tPOC) from annual leaf fall to lake food webs has not yet been adequately traced and quantified. In this study, we conducted whole-lake experiments to trace artificially added tPOC through the food webs of two shallow lakes of similar eutrophic status, but featuring alternative stable regimes (macrophyte rich vs. phytoplankton dominated). Lakes were divided with a curtain, and maize (Zea mays) leaves were added, as an isotopically distinct tPOC source, into one half of each lake. To estimate the …

Geosphere-biosphere interactions in bio-activity volcanic lakes: Evidences from Hule and Rìo Cuarto (Costa Rica)

2014

Hule and R ́ıo Cuarto are maar lakes located 11 and 18 km N of Poa ́s volcano along a 27 km long fracture zone, in the Central Volcanic Range of Costa Rica. Both lakes are characterized by a stable thermic and chemical stratification and recently they were affected by fish killing events likely related to the uprising of deep anoxic waters to the surface caused by rollover phenomena. The vertical profiles of temperature, pH, redox potential, chemical and isotopic compositions of water and dissolved gases, as well as prokaryotic diversity estimated by DNA fingerprinting and massive 16S rRNA pyrosequencing along the water column of the two lakes, have highlighted that different bio-geochemica…

Water mites of small boreal forest lakes (Central Finland)

1999

The water mite fauna of 10 small forest lakes in close proximity to each other was studied in 1979–1985. In total approximately 62 species of water mites belonging to 22 genera were detected in the lakes. The most diverse genera were Piona (14 species), Arrenurus (11), Unionicola (4) and Limnesia (4). Widely spread and abundant species were Piona variabilis and Limnesia maculata. Locally abundant were Unionicola crassipes, U. minor, Piona carnea and P. paucipora. Zoogeographically interesting though accidental species were Arrenurus werestschagini, Limnesia polonica, Momonia karelica, Piona gyrophora and Unionicola parvipora. Considerable spatial and seasonal differences were observed in th…

Modelling the impact of higher temperature on the phytoplankton of a boreal lake

2014

We linked the models PROTECH and MyLake to test potential impacts of climate-changeinduced warming on the phytoplankton community of Pyhäjärvi, a lake in southwest Finland. First, we calibrated the models for the present conditions, which revealed an apparent high significance of internal nutrient loading for Pyhäjärvi. We then estimated the effect of two climate change scenarios on lake water temperatures and ice cover duration with MyLake. Finally, we used those outputs to drive PROTECH to predict the resultant phytoplankton community. It was evident that cyanobacteria will grow significantly better in warmer water, especially in the summer. Even if phosphorus and nitrogen loads to the la…

Green sulphur bacteria as a component of the photosynthetic plankton community in small dimictic humic lakes with an anoxic hypolimnion

2013

High bacteriochlorophyll (BChl) concentrations in the anoxic water layers of some humic lakes have indicated that green sulphur bacteria (GSB) may be ecologically significant. The abundance and spatial distribution of GSB were therefore addressed in 13 small humic lakes using fragment analysis and sequencing of PCR-amplified 16S rRNA genes. GSB were detected from lakes where the photosynthetically active radiation was at least 1.1 µE m-2 s-1 at the oxic-anoxic boundary layer. In these lakes, 13 to 42% of the 16S rRNA gene sequences of the anoxic water column were assigned to GSB. The spatial distribution of GSB was tightly correlated with the spectrophotometrically measured BChl concentrati…

Multi-Temporal Soil Salinity Assessment at a Detailed Scale for Discriminating Halophytes Distribution

2016

A multi-temporal survey of soil salinity in a salt lake, recolonized by halophytes, was performed using electromagnetic induction (EMI) providing volume integrated values of soil apparent electrical conductivity (ECa). Inventories of plant communities were recorded according to the Braun-Blanquet method. In each of six areas monospecific with Suaeda vermiculata, Suaeda vera, Sarcocornia fruticosa, or Arthrocnemun macrostachyum, ECa was measured intensively in two seasons. Mean and range of ECa differ for each plant community. Soil was sampled in the six areas and analyzed for ion composition of the soil saturated paste extract. The electrical conductivity of the saturated paste extract (ECe…