BACKGROUND Several different classifications to characterize estuarine systems have been proposed. In this present paper, one of the most important estuaries in North Africa, the Oued Loukkos (Morocco), forms a case-study for proposing a systematic classification of this particular tidal estuary according to the vertical salinity gradient. FINDINGS This study, conducted using a CTD, shows tha...

The subarctic front is a thermohaline structure across the North Pacific, separating colder, fresher water to the north from warmer, saltier water to the south. Levitus's [1982] data and 72 conductivity-temperature-depth/salinity-temperature-depth sections are used to show the spatial and seasonal variations of the climatological frontal zone and the characteristics of the frontal structure in ...

One route to genetic adaptation in a novel environment is the evolution of ecological generalisation. Yet, identifying the cost that a generalist pays for the increased breadth of tolerance has proven elusive. We integrate phenotypic assays with functional genomics to understand how tolerance to a salinity gradient evolves, and we test the relationship between the fitness cost of this generalis...

Drivers of population genetic structure are still poorly understood in marine micro-organisms. We exploited the North Sea-Baltic Sea transition for investigating the seascape genetics of a marine diatom, Skeletonema marinoi. Eight polymorphic microsatellite loci were analysed in 354 individuals from ten locations to analyse population structure of the species along a 1500-km-long salinity gradi...

An estuary is a transition zone between freshwater and marine ecosystems, resulting in dilution of seawater. Estuaries are also considered environments of intense biological activity related to the processes of nutrient cycling. The aim of this study was to evaluate the microbial community composition along a salinity gradient in the estuary of the Cachoeira River, located in southern Bahia, Br...

Ecotones represent locations where vegetation change is likely to occur as a result of climate and other environmental changes. Using a model of an ecotone vulnerable to such future changes, we estimated the resilience of the ecotone to disturbances. The specific ecotone is that between two different vegetation types, salinity-tolerant and salinity-intolerant, along a gradient in groundwater sa...

We employed a cultivation-independent approach to examine archaeal diversity along a transient soil salinity gradient at Salt Spring in British Columbia, Canada that is routinely eroded due to heavy, recurrent rainfall. Archaeal 16S rRNA gene libraries were created using DNA extracted from three soil samples collected along this gradient. Statistical comparisons indicated similar archaeal richn...

The influence of altitude and salinity on bacterioplankton community composition (BCC) in 16 high-mountain lakes located at altitudes of 2,817 to 5,134 m on the Eastern Qinghai-Xizang (Tibetan) Plateau, China, spanning a salinity gradient from 0.02% (freshwater) to 22.3% (hypersaline), was investigated. Three different methods, fluorescent in situ hybridization, denaturing gradient gel electrop...

measuring salinity of water at different depths along six transacts at the mouth of the wetland and along five tributaries connecting the wetland to the sea the extent of caspian sea penetration into anzali wetland was determined. the results demonstrated a depth-dependent salinity gradient extending up to 10 kilometres into the wetland. a pattern of saltwater and freshwater interface is presen...

Chesapeake Bay, the largest estuary in North America, can be characterized as having steep and opposing gradients in salinity and dissolved inorganic nitrogen along the main axis of the Bay. In this study, the diversity of nirS gene fragments (encoding cytochrome cd 1-type nitrite reductase), physical/chemical parameters, and benthic N2-fluxes were analyzed in order to determine how denitrifier...