Search results for "lakes"

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…

Long-term competitive dynamics of two cryptic rotifer species: diapause and fluctuating conditions.

2015

Life-history traits may have an important role in promoting species coexistence. However, the complexity of certain life cycles makes it difficult to draw conclusions about the conditions for coexistence or exclusion based on the study of short-term competitive dynamics. Brachionus plicatilis and B. manjavacasare two cryptic rotifer species co-occurring in many lakes on the Iberian Peninsula. They have a complex life cycle in which cyclical parthenogenesis occurs with diapausing stages being the result of sexual reproduction. B. plicatilis and B. manjavacasare identical in morphology and size, their biotic niches are broadly overlapping, and they have similar competitive abilities. However,…

The unnoticed northward expansion of Najas marina subsp. armata (Hydrocharitaceae) in the Mediterranean area: an effect of climate change?

2022

Recent reports of Najas marina L. (Hydrocharitaceae) from Sicily have been interpreted as a confirmation of its presence on the island, where it was earlier mentioned in the 1800s. However the recent finds do not represent “N. marina” (currently N. major All.) but N. marina subsp. armata Horn (= N. delilei Rouy), a different taxon, previously not recorded from Sicily. According to those reports and several new finds presented here, it appears to be invading reservoirs and lakes in southern Sicily and seems to be naturally expanding its range. Climate change is suggested as possible cause of this shift. The same trend appears to be taking place across the whole N Mediterranean area, from Por…

Phytoplankton assemblages in twenty-one Sicilian reservoirs: relationships between species composition and environmental factors

2000

Data collected in a limnological survey, carried out between 1987 and 1988 on 21 Sicilian reservoirs of varying trophic state, were ordinated using CANOCO 3.1 to generalise the way in which the structure of phytoplankton assemblage is conditioned by both physical and chemical variables. The results showed that in these man-made lakes, characterised by conspicuouswater-level fluctuations, the annual and interannual variability in the abundance and composition of phytoplankton may be strongly influenced by their peculiar hydraulic regimes rather than by nutrient availability. In particular, it was highlighted that, from the early summer, water abstraction often leads to increased circulation …

Climate change and enhancement of water-level fluctuations in Mediterranean reservoirs: a sad fate for water quality?

2010

Tipologica ambiental de los sistemas leniticos de Huinay (Decima Region de Los Lagos, Chile) y distribucion del plancton limnico

2010

Mapping phycocyanin cells density of Planktothrix rubescens in freshwater reservoirs

2014

SMALL LAKES AND RESERVOIRS IN THE HILLS OF SICILY. MAINTAIN, SAVE AND RECOVER RURAL LANDSCAPE

2011

In the transition from nomadic to sedentary, people have tried - for their settlements - the most plenty of water, and the first cities were founded, in fact, along Tigris and Euphrates rivers, extraordinary water resources in a particular dry climate. In the most interior of Sicily, which has always been characterized by low rainfall, the farmers - over time - have tried various expedients for the preservation of rain water in order to allow its survival and crop. The use of new technologies and materials has resulted in recently hard impacts for landscape, while construction of small dams filled with earth, using natural soil impluviums and the nature of the land, made it possible to irri…

Heterogeneous vertical structure of the bacterioplankton community in a non-stratified Antarctic lake

2013

10 páginas, 4 figuras, 2 tablas.

Long-Term Coexistence of Rotifer Cryptic Species

2011

Despite their high morphological similarity, cryptic species often coexist in aquatic habitats presenting a challenge in the framework of niche differentiation theory and coexistence mechanisms. Here we use a rotifer species complex inhabiting highly unpredictable and fluctuating salt lakes to gain insights into the mechanisms involved in stable coexistence in cryptic species. We combined molecular barcoding surveys of planktonic populations and paleogenetic analysis of diapausing eggs to reconstruct the current and historical coexistence dynamics of two highly morphologically similar rotifer species, B. plicatilis and B. manjavacas. In addition, we carried out laboratory experiments using …