Search results for " phytoplankton"
showing 10 items of 37 documents
Dynamics of Two Picophytoplankton Groups in Mediterranean Sea: Analysis of the Deep Chlorophyll Maximum by a Stochastic Advection-Reaction-Diffusion …
2013
A stochastic advection-reaction-diffusion model with terms of multiplicative white Gaussian noise, valid for weakly mixed waters, is studied to obtain the vertical stationary spatial distributions of two groups of picophytoplankton, i.e., picoeukaryotes and Prochlorococcus, which account about for 60% of total chlorophyll on average in Mediterranean Sea. By numerically solving the equations of the model, we analyze the one-dimensional spatio-temporal dynamics of the total picophytoplankton biomass and nutrient concentration along the water column at different depths. In particular, we integrate the equations over a time interval long enough, obtaining the steady spatial distributions for th…
A European Multi Lake Survey dataset of environmental variables, phytoplankton pigments and cyanotoxins
2018
Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The Europea…
Shape and size in phytoplankton ecology: do they matter?
2007
This paper summarises the outcomes of the 14th Workshop of the International Association of Phytoplankton Taxonomy and Ecology (IAP). The authors mostly addressed their contributions on the following topics: morphological and morpho-functional descriptors of phytoplankton, size and shape structure of phytoplankton related to different kinds of environmental variables and the role of morphological and physiological plasticity of phytoplankton in maintaining the (apparently) same populations under different environmental conditions. Case studies from different kinds of aquatic environments (deep and shallow lakes, reservoirs with different age, purpose and trophic state, floodplain wetlands m…
Functional classifications and their application in phytoplankton ecology
2015
SUMMARY 1. Ecologists often group organisms based on similar biological traits or on taxonomic criteria. However, the use of taxonomy in ecology has many drawbacks because taxa may include species with very different ecological adaptations. Further, similar characters may evolve independently in different lineages. 2. In this review, we examine the main criteria that have been used in the identification of nine modes of classifying phytoplankton non-taxonomically. These approaches are based purely on morphological and/or structural traits, or on more complex combinations including physiological and ecological features. 3. Different functional approaches have proved able to explain some frac…
Phytoplankton communities of polar regions–Diversity depending on environmental conditions and chemical anthropopressure
2015
The polar regions (Arctic and Antarctic) constitute up to 14% of the biosphere and offer some of the coldest and most arid Earth's environments. Nevertheless several oxygenic phototrophs including some higher plants, mosses, lichens, various algal groups and cyanobacteria, survive that harsh climate and create the base of the trophic relationships in fragile ecosystems of polar environments. Ecosystems in polar regions are characterized by low primary productivity and slow growth rates, therefore they are more vulnerable to disturbance, than those in temperate regions. From this reason, chemical contaminants influencing the growth of photoautotrophic producers might induce serious disorders…
Specific detection of cyclobutane pyrimidine dimers in phytoplankton DNA by a non-radioactive assay based on T4-endonuclease V digestion.
2001
The effect of artificial and natural UV irradiation on DNA in marine phytoplankton Isochrysis galbana monoculture was investigated. The presence of cyclobutane pyrimidine dimers (CPDs) in unlabelled I. galbana DNA was detected by a non-radiometric alkaline filter elution assay after T4-endonuclease V digestion. The quantity of CPDs was estimated by alkaline agarose gel electrophoresis. Precise determination of the amount of DNA in the presence of I. galbana pigments was achieved by oxazole yellow homodimer (YOYO) dye. T4-endonuclease V-sensitive sites frequency (ESS/kb), measured after exposure to 2-40 kJ m(-2) of artificial UV light, increased in a dose-dependent manner. Twelve hours after…
Use and misuse in the application of the phytoplankton functional classification: a critical review with updates
2008
Since its publication, the article ‘Towards a functional classification of the freshwater phytoplankton’ (Reynolds et al., J Plankton Res 24: 417–428, 2002), has attracted the attention of dozens of phytoplankton ecologists worldwide. These numerous applications of the functional classification to describe phytoplankton patterns in various aquatic ecosystems allowed the recognition of some uncertain features of this concept originating from various reasons. In this article, we attempt to facilitate the application of the functional classification, by providing a detailed description of the typical misplacements and by modifying some of the original habitat templates and species allocations.…
Preface: Biogeography and spatial patterns of biodiversity of freshwater phytoplankton
2016
Convergence and divergence in organization of phytoplankton communities under various regimes of physical and biological control
2010
The hypothesis that physical constraints may be as important, if not more important, than biological ones in shaping the structure of phytoplankton assemblage was tested by analyzing longterm (11–29 years) phytoplankton series in eight lakes and nine sites located along a latitudinal gradient in the Northern hemisphere. Phytoplankton biomass was used and similarity of assemblages in same months of the annual data sets was then calculated by subtracting the Bray–Curtis dissimilarity index from 1. The extent of biological and physical forcing was partly based on ‘‘expert evaluation’’: the importance of four physical (light availability, temperature, conductivity, and sediment stirring up) and…