Search results for "Crust"
showing 9 items of 599 documents
Isolation and characterization of microsatellite markers in the portunid crab Liocarcinus depurator using FIASCO and 454 next-generation sequencing
2012
The portunid crab Liocarcinus depurator is the dominant decapod crustacean present on mud bottoms of the continental shelf of the Mediterranean Sea. In order to better describe its genetic structure, a total of 11 microsatellites were isolated and tested in 28 L. depurator individuals from the Mediterranean locality of Tarragona. Initially, microsatellite isolation was carried out using the FIASCO methodology, but only 2 useful primer pairs could be designed. Given the low yield obtained, an alternative method based on 454 next-generation sequencing was assayed, which provided excellent results and from which another 9 primer pairs gave positive genotyping. All loci tested were polymorphic,…
Impacts of reduced Lepidurus arcticus availability on brown trout life history traits in a mountain reservoir
2020
Lepidurus arcticus (the Arctic tadpole shrimp) is a vulnerable keystone species in Arctic and alpine water bodies where its occurrence and population size may influence the viability and life history traits of resident salmonids. Using data from a Norwegian mountain hydropower reservoir, Aursjoen, we illustrate how reduced availability of L. arcticus as prey resulted in the reduced condition, growth and delayed maturation of resident brown trout (Salmo trutta). We further link changes in the relative abundance of L. arcticus as prey to changing reservoir conditions, e.g. water level changes in the spring period, thereby establishing an indirect link between reservoir operation regimes and b…
Jättikatkan (Gammaracanthus lacustris) ja jäännehalkoisjalkaisen (Mysis relicta) koko- ja tiheysjakaumat Saimaan Paasivedellä; Vertical size and dens…
2010
The ecology of relict crustaceans in Finnish lakes is quite poorly known. In this study we investigated the vertical distributions of these species in Lake Saimaa in the depth zones between 30 m and 60 m. We found out that Gammaracanthus. lacustris lives mainly in the deepest parts of the lake, while Mysis relicta favours the shallowest zones. The average length of both species increased with the depth in the study area. There were some differences in distributions between years, but the main reasons for that are not known exactly. peerReviewed
Makroäyriäisten (Gammaracanthus lacustris, Mysis relicta, Monoporeia affinis, Pallaseopsis quadrispinosa) vuorokausivaellukset Saimaan Paasivedellä; …
2010
We examined the diel vertical migrations of the macroscopic pelagic relict crustaceans Gammaracanthus lacustris, Mysis relicta, Monoporeia affinis and Pallaseopsis quadrispinosa in the deep Lake Paasivesi basin of the Saimaa lake complex. The samples were collected in October 2006 and 2007 using a Hydro-Bios Multi Plankton Sampler onboard the research vessel R/V Muikku. The study provides information about the day-and-night and year-to-year changes in the vertical distribution of these crustaceans. Regarding G. lacustris we explored if body size (length), sex or maturity have bearing on the individuals' depth preference or possible diel migrations. We noticed that G. lacustris females occur…
Evolution des paysages Sahélines au cours des six dernières décennies dans la région de Niamey : de la disparition de la brousse tigrée à l'encroutem…
2010
In the Sahel, the rapid increase of the population during the last decades and the climate variation lead to an important environmental degradation. This work aims to measure the impacts of the human pressure on ecosystem during the six last decades. A diachronic cartography of a 100 km² area close to Niamey was done with aerial photographs (1950 and 1975) and GPS measurements (2009). Results showed that the tiger bush vegetation was completely cleared between 1950 and 2009 while the fallow decreases from 7 % to 1 %. In the sandy valley, the increase of cultivated fields from 20,7 % (1950) to 69,4 % (1975) favoured wind and water erosions which allowed surface soil crusting. Between 1975 an…
A simple field method to measure the hydrodynamic properties of soil surface crust
2013
The hydraulic resistance of the surface crust was determined by a combination of two infiltrometric techniques: first, a surface measurement of steady-state infiltration rate is conducted by a mini-disk tension infiltrometer (MDI); then, the surface crust is removed, its thickness is measured, and a ponded infiltration test is performed at the same site. The Beerkan Estimation of Soil Transfer parameters (BEST) method is applied to estimate the hydraulic properties of the underlying soil provided the particlesize distribution and the bulk density are known. Under the assumption of a unit gradient of hydraulic head below the soil crust, the pressure head at the interface crust-soil is derive…
Upper thermal threshold of Lepidurus arcticus (Branchiopoda, Notostraca) in lakes on the southern outreach of its distribution range
2021
Qvenild T, Fjeld E, Fjellheim A, Hammar J, Hesthagen T and Lakka H-K. 2021. Upper thermal threshold of Lepidurus arcticus (Branchiopoda, Notostraca) in lakes on the southern outreach of its distribution range. Fauna norvegica 41: 50–88. The Arctic tadpole shrimp Lepidurus arcticus has a circumpolar distribution and the Scandes (Fennoscandian Mountains) marks its southernmost limit in Europe. Within this area, 391 natural and 88 regulated lakes with L. arcticus have been identified, of which 87% are above the treeline. The lakes hosting L. arcticus decrease in altitude from south to north, which results from its temperature preferences. The majority of the locations are at a lower lake air t…
Ureteral stent encrustation: evaluation of available scores as predictors of a complex surgery
2022
Background: Stent Encrustation is an uncommon event (13%) with a significant impact in patients' management. Aim of our study was to evaluate the available grading systems for encrusted stents. Methods: A retrospective analysis of encrusted stents was performed in four Italian centers between 2006 and 2020. Encrusted stents were classified according to four classifications: the Forgotten Encrusted Calcificated (FECal) score, the Kidney Ureter Bladder (KUB) score, the Visual Grading for Ureteral Encrusted Stent Classification and the Encrustation Burden Score (EBS). Classifications were evaluated to predict complex surgery defined as: long operative time (>60min); need of more than one su…
Author Correction: Evaluation of three methods for biomass estimation in small invertebrates, using three large disparate parasite species as model o…
2018
Invertebrate biomass is considered one of the main factors driving processes in ecosystems. It can be measured directly, primarily by weighing individuals, but more often indirect estimators are used. We developed two indirect and non-destructive approaches to estimate biomass of small invertebrates in a simple manner. The first one was based on clay modelling and the second one was based on image analysis implemented with open-source software. Furthermore, we tested the accuracy of the widely used geometric approximation method (third method). We applied these three different methods to three morphologically disparate model species, an acanthocephalan worm, a crustacean and a flatworm. To …