Search results for "ck"
showing 10 items of 18632 documents
Grape root as habitat: overwintering and population dynamics of grape phylloxera (Daktulosphaira vitifoliae Fitch) in temperate climate viticulture
2016
Background and Aims Daktulosphaira vitifoliae Fitch (grape phylloxera, Phylloxeridae) is one of the most devastating pests in viticulture, mainly because of their root feeding activity. Up to today fundamental relations between belowground habitat and population dynamics remain unclear. In this 2-year study, we investigated the relations between grape phylloxera population and phenotypic traits of roots and feedings sites. Methods and Results We extracted root and soil samples frequently of two closely related mature rootstocks [Vitis berlandieri × V. riparia (cvs 5C and 125AA)]. We quantified and characterised larval population and crowding and assessed root gall pigmentation, root morphol…
Holocephalan (Chondrichthyes) dental plates with hypermineralized dentine as a substitute for missing teeth through developmental plasticity.
2020
All extant holocephalans (Chimaeroidei) have lost the ability to make individual teeth, as tooth germs are neither part of the embryonic development of the dental plates, nor of their continuous growth. Instead, a hypermineralized dentine with a unique mineral, whitlockin, is specifically distributed within a dentine framework into structures that give the dental plates their distinctive, species-specific morphology. Control of the regulation of this distribution must be cellular, with a dental epithelium initiating the first outer dentine, and via contact with ectomesenchymal tissue as the only embryonic cell type that can make dentine.\ud Chimaeroids have three pairs of dental plates with…
The invasive Asparagopsis taxiformis hosts a low diverse and less trophic structured molluscan assemblage compared with the native Ericaria brachycar…
2021
Abstract Invasive seaweeds threaten biodiversity and socio-economics values of worldwide marine ecosystems. Understanding to what extent invasive seaweeds can modify local biodiversity is one of the main priorities in conservation ecology. We compared the molluscan assemblage of the invasive Asparagopsis taxiformis with that of the native Ericaria brachycarpa and explore if variation in the molluscan assemblage diversity was related to the substrate attributes (biomass, and thallus, canopy, and interstitial volumes) of the algae. Results showed that A. taxiformis harboured lower diversity and trophic structure of the molluscan assemblage compared to E. brachycarpa. Biomass was the variable …
Classification of the European marsh vegetation (Phragmito‐Magnocaricetea) to the association level
2020
Aims: To create a comprehensive, consistent and unequivocal phytosociological classification of European marsh vegetation of the class Phragmito-Magnocaricetea. Location: Europe. Methods: We applied the Cocktail method to a European data set of 249, 800 vegetation plots. We identified the main purposes and attributes on which to base the classification, defined assignment rules for vegetation plots, and prepared formal definitions for all the associations, alliances and orders of the class Phragmito-Magnocaricetea using formal logic. Each formula consists of the combination of “functional species groups”, cover values of individual species, and in the case of high-rank syntaxa also of “disc…
Reconstruction of Atlantic herring ( Clupea harengus ) recruitment in the North Sea for the past 455 years based on the δ 13 C from annual shell incr…
2019
Understanding the recruitment variability of the Atlantic herring North Sea stock remains a key objective of stock assessment and management. Although many efforts have been undertaken linking climatic and stock dynamic factors to herring recruitment, no major attempt has been made to estimate recruitment levels before the 20th century. Here, we present a novel annually resolved, absolutely dated herring recruitment reconstruction, derived from stable carbon isotope geochemistry (δ¹³C), from ocean quahog shells from the Fladen Ground (northern North Sea). Our age model is based on a growth increment chronology obtained from fourteen shells. Ten of these were micromilled at annual resolution…
Synthesis of habitat restoration impacts on young-of-the-year salmonids in boreal rivers
2019
River restoration offers the potential to enhance biological integrity, often measured as fish population changes. We used a meta-analytical approach to synthesize density responses to in-stream habitat restoration by young-of-the year (YOY) brown trout and Atlantic salmon in 28 rivers (overall 32 restoration projects) in Finland. We also examined which local and watershed-scale factors most influenced restoration success. Finally, we conducted an expert survey to obtain an independent estimate of a sufficient density enhancement for restoration to be considered successful. Despite strong context-dependency, habitat restoration had an overall positive effect on YOY salmonid density. When co…
Coping with Difficult Weather and Snow Conditions : Reindeer herders’ views on climate change impacts and coping strategies
2016
Winter is a critical season for reindeer herding, with the amount and quality of snow being among the most important factors determining the condition of reindeer and the annual success of the livelihood. Our first aim was to model the future (2035–2064) snow conditions in northern Finland, especially the quantities related to ground ice and/or ice layers within the snow pack, exceptionally deep snow and late snow melt. Secondly, we studied the strategies by which herders cope with the impacts of difficult weather and snow conditions on herding by interviewing 21 herders. SNOWPACK simulations indicate that snow cover formation will be delayed by an average of 19 days and snow will melt 16 d…
Primary production calculations for sea ice from bio-optical observations in the Baltic Sea
2016
Abstract Bio-optics is a powerful approach for estimating photosynthesis rates, but has seldom been applied to sea ice, where measuring photosynthesis is a challenge. We measured absorption coefficients of chromophoric dissolved organic matter (CDOM), algae, and non-algal particles along with solar radiation, albedo and transmittance at four sea-ice stations in the Gulf of Finland, Baltic Sea. This unique compilation of optical and biological data for Baltic Sea ice was used to build a radiative transfer model describing the light field and the light absorption by algae in 1-cm increments. The maximum quantum yields and photoadaptation of photosynthesis were determined from 14C-incorporatio…
First Observation of a Four-egg Clutch of Long-tailed Jaeger (Stercorarius longicaudus)
2015
5 pages; International audience; Long-tailed Jaegers (Stercorarius longicaudus) normally lay one or two eggs (rarely three), with a maximum of two eggs set by the existence of only two brood patches. Here, however, we present the first documentation of a clutch of four eggs in a Long-tailed Jaeger nest found at Zackenberg in northeastern Greenland.
Modelling prey-predator interactions in Messina beachrock pools
2020
Abstract The Strait of Messina (Sicily, Italy) attracts the interest of marine ecologists for the presence of a large variety of habitat and mutually-interacting communities. Among them, beachrock formations, despite their wide geographic distribution, which also includes the Mediterranean area, have been poorly investigated from the biotic viewpoint. In this paper, the spatial and seasonal variability of benthic megafauna from the Messina microtidal beachrock is described. Combining in situ collected data (measurements of abiotic parameters and underwater visual census) with theoretical post-processing analyses (analysis of similarity percentages and cluster analysis), we deduced the possi…