Journal ArticleDOI
Ecological thresholds in European alpine lakes
Jordi Catalan,M. Grazia Barbieri,Frederic Bartumeus,Peter Bitušík,Ivan Botev,Anton Brancelj,Dan Cogălniceanu,Marina Manca,Aldo Marchetto,Nadja Ognjanova-Rumenova,Sergi Pla,Maria Rieradevall,Sanna Sorvari,Elena Štefková,Evžen Stuchlík,Marc Ventura,Marc Ventura +16 more
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In this paper, the authors found a hierarchical structure in the community assemblage using distinct scales of lake clustering (number of k-means groups) based on species composition similarity (Hellinger distance).Abstract:
SUMMARY 1. Species assemblages of diatoms, rotifers, chydorids, planktonic crustaceans and chironomids were studied in 235 alpine lakes in the Alps, Pyrenees, Tatras (Western Carpathians), Retezat (Southern Carpathians) and Rila Mountains (Balkans). 2. For all taxonomic groups we found a hierarchical structure in the community assemblage using distinct scales of lake clustering (number of k-means groups) based on species composition similarity (Hellinger distance). We determined the optimal partition in assemblage types (i.e. number of lake clusters) for each taxonomic group by maximising the sum of the taxon indicative value (IndVal) and performed discriminant analyses, using environmental variables not conditioned by geographical patterns. Relevant environmental variables differed among and within taxonomic groups. Therefore the assemblages respond to a complex environmental mosaic, with the exception of diatom assemblages, which followed an acid–base gradient. 3. The significant environmental variables could be grouped into four general factors: lake size, tropho-dynamic status, acid–base balance and ice-cover duration (i.e., altitudinal gradient). Lake size was significant for the highest number of assemblage types; however, the most significant factor differed among taxonomic groups: acid–base balance for diatoms, lake size for rotifers, ice-cover duration for chydorids and planktonic crustaceans and tropho-dynamic status for chironomids. No single environmental typology accounted for the assemblage structure of all taxonomic groups. 4. However, defining ecological thresholds as values within environmental gradients at which the rate of change in assemblages is accelerated relative to points distant from thatread more
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Journal ArticleDOI
How do freshwater organisms cross the “dry ocean”? A review on passive dispersal and colonization processes with a special focus on temporary ponds
TL;DR: The existence of a sharp decoupling between “dispersal potential” and “actual establishment rates” is stressed, thus urging a definitive overcome of the so-called “Everything is Everywhere” hypothesis in order to gain a proper understanding of the biogeography and ecology of inland water organisms.
Journal ArticleDOI
Assembly mechanisms determining high species turnover in aquatic communities over regional and continental scales
Duarte S. Viana,Jordi Figuerola,Klaus Schwenk,Marina Manca,Anders Hobæk,Anders Hobæk,Marit Mjelde,Christopher D. Preston,Richard J. Gornall,J. M. Croft,R. A. King,Andy J. Green,Luis Santamaría +12 more
TL;DR: The results suggest that, although dispersal limitation might affect species composition in some regions, aquatic plant and cladoceran communities are not generally limited by dispersal at the regional scale (up to 300 km).
Journal ArticleDOI
Perspectives for ecosystem management based on ecosystem resilience and ecological thresholds against multiple and stochastic disturbances
TL;DR: In this article, the authors present two perspectives for providing a predictive scientific basis to the management and conservation of ecosystems against multiple and stochastic disturbances, namely, management of predictable anthropogenic disturbances to maintain a sufficient level of biodiversity for ensuring ecosystem resilience (i.e., resilience-based management).
Journal ArticleDOI
Regionalisation of remote European mountain lake ecosystems according to their biota: environmental versus geographical patterns.
Martin Kernan,Marc Ventura,Marc Ventura,Peter Bitušík,Anton Brancelj,G Clarke,Gaute Velle,Gunnar G. Raddum,Evžen Stuchlík,Jordi Catalan +9 more
TL;DR: In this paper, a survey of 350 remote high altitude and high latitude lakes from 11 different mountain regions was undertaken to explore species distribution across Europe at a scale not previously attempted, where each lake was characterised in terms of water chemistry, morphology, catchment attributes and geographical location.
Journal ArticleDOI
Remote European mountain lake ecosystems: regionalisation and ecological status
TL;DR: A survey of 350 remote high altitude and high latitude lakes from 12 different mountain regions across Europe was undertaken to explore ecosystem variability, climate forcing, environmental conditions and pollution threats at a scale not previously attempted as mentioned in this paper.
References
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Book
Finding Groups in Data: An Introduction to Cluster Analysis
TL;DR: An electrical signal transmission system, applicable to the transmission of signals from trackside hot box detector equipment for railroad locomotives and rolling stock, wherein a basic pulse train is transmitted whereof the pulses are of a selected first amplitude and represent a train axle count.
BookDOI
Finding Groups in Data
TL;DR: In this article, an electrical signal transmission system for railway locomotives and rolling stock is proposed, where a basic pulse train is transmitted whereof the pulses are of a selected first amplitude and represent a train axle count, and a spike pulse of greater selected amplitude is transmitted, occurring immediately after the axle count pulse to which it relates, whenever an overheated axle box is detected.
Journal ArticleDOI
Species assemblages and indicator species:the need for a flexible asymmetrical approach
Marc Dufrêne,Pierre Legendre +1 more
TL;DR: A new and simple method to find indicator species and species assemblages characterizing groups of sites, and a new way to present species-site tables, accounting for the hierarchical relationships among species, is proposed.
Journal ArticleDOI
Ecologically meaningful transformations for ordination of species data
TL;DR: Transitions are proposed for species data tables which allow ecologists to use ordination methods such as PCA and RDA for the analysis of community data, while circumventing the problems associated with the Euclidean distance, and avoiding CA and CCA which present problems of their own in some cases.
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