Search results for "limnology"

Clostridium perfringens (Holland) as an indicator of human effluent in the sediment of Lake Tuomiojärvi, central Finland

1983

The horizontal and vertical distribution of the gram-positive, non-motile, spore-forming and rod-shaped bacterium Clostridium perfringens Holland was studied. The aim of the study was to estimate the quantity of C. perfringens at different depths of the sediment and evaluate the effect of human effluent which the lake received between 1940 and 1956. C. perfringens lives in the colon of man. Because it is spore forming and cannot multiply under a temperature of 20 °C and, according to the studies of Seppanen et al. (1979) it can be at least 300 years old, it may be a suitable paleolimnological indicator of pollution by human effluent.

Variability in δ13C values between individual Daphnia ephippia: Implications for palaeo-studies

2018

The stable carbon isotope ratio (δ13C value) of Daphnia spp. resting egg shells (ephippia) provides information on past changes in Daphnia diet. Measurements are typically performed on samples of ≥20 ephippia, which obscures the range of values associated with individual ephippia. Using a recently developed laser ablation-based technique, we perform multiple δ13C analyses on individual ephippia, which show a high degree of reproducibility (standard deviations 0.1–0.5‰). We further measured δ13C values of 13 ephippia from surface sediments of three Swiss lakes. In the well-oxygenated lake with low methane concentrations, δ13C values are close to values typical for algae (−31.4‰) and the rang…

Effects of Changing Rainfall on the Limnology of a Mediterranean, Flowthrough-Seepage Chain of Lakes

2006

Relationships between groundwater and lake ecology are often overlooked, but they may be strong, particularly in seepage lakes. As a result, the nature and degree of groundwater effects on lakes are usually neglected. In this study interactions among rainfall, groundwater and surface water and their limnological effects were traced seasonally for two years of changing rainfall in a Spanish flowthrough, seepage lake complex. Cumulative rainfall dictated recharge of groundwater with delays of nine months. Groundwater discharge, in turn, increased surface discharge downstream. Mediated by the geographical setting of lakes, both fluxes impinged on lake water renewal time, but effects of the lat…

Quantifying unpredictability: A multiple-model approach based on satellite imagery data from Mediterranean ponds.

2017

Fluctuations in environmental parameters are increasingly being recognized as essential features of any habitat. The quantification of whether environmental fluctuations are prevalently predictable or unpredictable is remarkably relevant to understanding the evolutionary responses of organisms. However, when characterizing the relevant features of natural habitats, ecologists typically face two problems: (1) gathering long-term data and (2) handling the hard-won data. This paper takes advantage of the free access to long-term recordings of remote sensing data (27 years, Landsat TM/ETM+) to assess a set of environmental models for estimating environmental predictability. The case study inclu…

On Infiltration and Infiltration Characteristic Times

2022

In his seminal paper on the solution of the infiltration equation, Philip (1969), https://doi.org/10.1016/b978-1-4831-9936-8.50010-6 proposed a gravity time, tgrav, to estimate practical convergence time and the time domain validity of his infinite time series expansion, TSE, for describing the transient state. The parameter tgrav refers to a point in time where infiltration is dominated equally by capillarity and gravity as derived from the first two (dominant) terms of the TSE. Evidence suggests that applicability of the truncated two-term equation of Philip has a time limit requiring higher-order TSE terms to better describe the infiltration process for times exceeding that limit. Since …

Different invasibility of permanent and temporary waterbodies in a semiarid Mediterranean Island

2019

Nonindigenous species (NIS) represent a threat to aquatic biodiversity worldwide. However, freshwater ecosystems in drylands are potentially more prone to biological invasions than those located in temperate regions because of the higher number of artificial waterbodies generally occurring in these areas, which might act as invasion hubs for NIS. We review the available information about NIS in Sicilian waterbodies, discuss the role exerted by artificial lakes and ponds in facilitating the establishment of NIS in arid and semiarid areas, and compare the invasibility of permanent and temporary waterbodies in drylands. Artificial waterbodies increase the target-area effect for dispersers and …

Limnological characterization of 16 lentic water bodies belonging to the territory of the ‘Fundación San Ignacio Del Huinay’, X region de Los Lagos, …

2009

Huinay is a territory covering about 34,000 hectares in the Commune of Hualaihué (Xth region of Chile) and belonging to the San Ignacio del Huinay Foundation (HF). Its location (42° 22´ S; 72° 24´ W) corresponds to the bio-geographical Province of Magallanes and specifi cally to an area which is highly representative of the continental Northern Patagonia. Based on an aerial prospecting conducted during 2008, we identifi ed more than 30 water bodies of different size and morphology, occurring at different heights and in different landscapes. Among these, 16 water bodies were selected to be studied at the end of the summer, in February 2009. In each water body, longitudinal and transversal ba…

First contribute to the limnological knowledge of lentic water bodies belonging to the territory of the 'Fundacion San Ignacio del Huinay' (X region …

2008

Variation of suspended and sedimentary organic matter with depth in shallow coastal waters

2009

I tested the hypothesis that the quantity and quality of suspended and sediment organic matter in shallow coastal waters is affected by wind-induced resuspension at a smaller depth scale (, 1 m) than usually assumed. Water and sediment surface (0 to 1 cm) samples were collected on a seasonal basis and analyzed for total suspended matter, organic fraction, and phytopigments at 12 shallow sites representing a depth gradient from 0.2 to 2.0 m along the western shore of Sicily. Water column concentrations of all measured variables decreased rapidly with increasing water column depth, and concentrations levelled off at about 1 m water column depth. The likelihood of sediment resuspension by wind…

Role of terrestrial carbon in aquatic UV exposure and photoprotective pigmentation of meiofauna in subarctic lakes

2015

Summary Aquatic organisms are adversely influenced by ultraviolet radiation (UV) and utilise photoprotective strategies, including pigmentation. We examined UV-protective melanin pigmentation of aquatic meiofauna (Cladocera) in relation to the UV exposure across 25 tree line lakes in Finland to address the potential effects of increased UV and altered input of UV-screening terrestrial dissolved organic carbon (DOC) on aquatic organisms. Bio-optical parameters, including concentration of DOC, the coloured dissolved organic matter (CDOM) fraction, a suite of carbon quality indices and chlorophyll a, were analysed from lake water, and their role in controlling underwater UV environment (measur…