Search results for "Limnology"

Bacterial and phytoplankton responses to nutrient amendments in a boreal lake differ according to season and to taxonomic resolution

2011

Nutrient limitation and resource competition in bacterial and phytoplankton communities may appear different when considering different levels of taxonomic resolution. Nutrient amendment experiments conducted in a boreal lake on three occasions during one open water season revealed complex responses in overall bacterioplankton and phytoplankton abundance and biovolume. In general, bacteria were dominant in spring, while phytoplankton was clearly the predominant group in autumn. Seasonal differences in the community composition of bacteria and phytoplankton were mainly related to changes in observed taxa, while the differences across nutrient treatments within an experiment were due to chang…

Development of temperature and oxygen gradients during the formation of ice cover in a deep boreal lake

2008

Recent changes in chironomid communities and hypolimnetic oxygen conditions relate to organic carbon in subarctic ecotonal lakes

2018

A key question in aquatic elemental cycling is related to the influence of bottom water oxygen conditions in regulating the burial and release of carbon under climate warming. In this study, we used head capsules of Chironomidae larvae to assess community and diversity change between the past (estimated as Pre-Industrial Period) and present and to reconstruct changes in hypolimnetic oxygen conditions from 30 subarctic ecotonal lakes (northeastern Lapland) using the top-bottom paleolimnological approach applying surface sediment (topmost 0-2 cm) and reference (4-5 cm) samples. Subsequently, we tested the findings against dissolved organic carbon (DOC) concentration of the sites. We found tha…

Homage to Proserpina, or: why did the charophytes of the Pergusa Lake vanish?

2020

An important bisexual population of the charophyte Chara canescens Loisel. (Characeae, Charales, Charophyceae) was reported in the XIX century for the Pergusa Lake (Sicily). A recent field survey to check its presence revealed that it has disappeared. After a bibliographic research to understand when and why this happened, the input of freshwater from outside the basin and the introduction of the carps were identified as the two main causes for its recent extinction. Some possible management measures to try to restore the lake ecosystem are proposed.

Relationship between cladoceran (Crustacea) functional diversity and lake trophic gradients

2017

Functional diversity (FD) as a biodiversity measure has an explicit role in ecosystem functioning because the effects of environmental changes in ecosystems are determined by biological functions, such as feeding type and trophic position, of particular species. We evaluated the usability of functional characterization and FD of an aquatic keystone group (Crustacea: Cladocera) for enhancing the understanding of long-term lake functional responses to environmental changes. The aims were to separate ecologically significant functional groups, investigate succession of such functional groups during nutrient enrichment process and determine the relationship between FD and lake productivity usin…

Long-term changes in pigmentation of arctic Daphnia provide potential for reconstructing aquatic UV exposure

2016

Abstract Despite the biologically damaging impacts of solar ultraviolet radiation (UV) in nature, little is known about its natural variability, forcing mechanisms, and long-term effects on ecosystems and organisms. Arctic zooplankton, for example the aquatic keystone genus Daphnia (Crustacea, Cladocera) responds to biologically damaging UV by utilizing photoprotective strategies, including pigmentation. We examined the preservation and content of UV-screening pigments in fossil Daphnia remains (ephippia) in two arctic lake sediment cores from Cornwallis Island (Lake R1), Canada, and Spitsbergen (Lake Fugledammen), Svalbard. The aims were to document changes in the degree of UV-protective p…