92 research outputs found
Ecosystem services provided by marine and freshwater phytoplankton
Phytoplankton, the ecological group of microalgae adapted to live in apparent suspension in water masses, is much more than an ecosystemâs engineer. In this opinion paper, we use our experience as phytoplankton ecologists to list and highlight the services provided by phytoplankton, trying to demonstrate how their activity is fundamental to regulate and sustain Life on our Planet. Although the number of services produced by phytoplankton can be considered less numerous than that produced by other photosynthetic organisms, the ubiquity of this group of organisms, and their thriving across oceanic ecosystems make it one of the biological engines moving our biosphere. Supporting services provided by phytoplankton include almost half of the global primary and oxygen production. In addition, phytoplankton greatly pushes biogeochemical cycles and nutrient (re)cycling, not only in aquatic ecosystems but also in terrestrial ones. In addition, it significantly contributes to climate regulation (regulating services), supplies food, fuels, active ingredients and drugs, and genetic resources (provisioning services), has inspired artistic and craft works, mythology, and, of course, science (cultural services), and much more. Therefore, phytoplankton should be considered in all respects a true biosphereâs engineer
Functional classifications in phytoplankton ecology: a comparative review of approaches and experiences
3openEmpirical models of phytoplankton groups and their recurrence in water bodies have traditionally made use of taxonomic classifications, implicitly or explicitly assuming that species classified together could share similar ecological properties. Nevertheless, the use of taxonomy in ecology has many drawbacks. From one side, many broader groups include species with very different ecological properties. From the other side, convergent evolution, the independent evolution of similar characters in different lineages, can explain why distantly phylogenetically related species can be linked together by close analogous ecological affinities. With the aim to obtain a better understanding of the functioning of the freshwater ecosystems, complementary approaches based on ecological criteria have been therefore proposed. The aim of this contribution is to critically review the rationale of the different classifications that have been proposed during the last three decades, highlighting the strengths and weaknesses of the different approaches. Besides the first classifications, which considered broad functional categories based on reproductive (r-K selection) and life strategies (C-S-R), successive formulations included the functional groups (FG), firstly established by C.S. Reynolds, the Morpho-Functional Groups (MFG- Salmaso & PadisĂĄk, 2007), and the Morphology-Based Functional Groups (MBFG - Kruk et al., 2010). In the original formulation of FG, species were put together if they showed similar dynamics and ecological requirements, implicitly assuming a similar response to a set of environmental and seasonal changing conditions. With successive refinements, morphological properties have been used to fit hitherto functionally unclassified taxa into existing FG. This classification has been widely used in many aquatic ecosystems, with applications in ecological status assessment. At the opposite, MBFG (totalling 7 groups) are exclusively based on morphological characters, irrespective of the temporal dynamics of the species. The MFG concept use a hybrid approach, integrating morphological, functional and, when ecologically relevant, taxonomic characters in the definition of groups. The comparative evaluation of the above classifications was attempted only very recently, and will be critically examined in this review. Finally, this work will provide an updating of the original MFG classification based on the application of the concept to real case phytoplankton studies.openSalmaso, N.; Naselli Flores, L.; PadisĂĄk, J.Salmaso, N.; Naselli Flores, L.; PadisĂĄk, J
Seasonality of parasitic and saprotrophic zoosporic fungi: linking sequence data to ecological traits
Zoosporic fungi of the phylum Chytridiomycota (chytrids) regularly dominate pelagic fungal communities in freshwater and marine environments. Their lifestyles range from obligate parasites to saprophytes. Yet, linking the scarce available sequence data to specific ecological traits or their host ranges constitutes currently a major challenge. We combined 28âS rRNA gene amplicon sequencing with targeted isolation and sequencing approaches, along with cross-infection assays and analysis of chytrid infection prevalence to obtain new insights into chytrid diversity, ecology, and seasonal dynamics in a temperate lake. Parasitic phytoplankton-chytrid and saprotrophic pollen-chytrid interactions made up the majority of zoosporic fungal reads. We explicitly demonstrate the recurrent dominance of parasitic chytrids during frequent diatom blooms and saprotrophic chytrids during pollen rains. Distinct temporal dynamics of diatom-specific parasitic clades suggest mechanisms of coexistence based on niche differentiation and competitive strategies. The molecular and ecological information on chytrids generated in this study will aid further exploration of their spatial and temporal distribution patterns worldwide. To fully exploit the power of environmental sequencing for studies on chytrid ecology and evolution, we emphasize the need to intensify current isolation efforts of chytrids and integrate taxonomic and autecological data into long-term studies and experiments.Alliance of German Science Organizations///AlemaniaUCR::VicerrectorĂa de Docencia::Ciencias BĂĄsicas::Facultad de Ciencias::Escuela de BiologĂ
Seasonality of parasitic and saprotrophic zoosporic fungi: linking sequence data to ecological traits
Zoosporic fungi of the phylum Chytridiomycota (chytrids) regularly dominate pelagic fungal communities in freshwater and marine environments. Their lifestyles range from obligate parasites to saprophytes. Yet, linking the scarce available sequence data to specific ecological traits or their host ranges constitutes currently a major challenge. We combined 28 S rRNA gene amplicon sequencing with targeted isolation and sequencing approaches, along with cross-infection assays and analysis of chytrid infection prevalence to obtain new insights into chytrid diversity, ecology, and seasonal dynamics in a temperate lake. Parasitic phytoplankton-chytrid and saprotrophic pollen-chytrid interactions made up the majority of zoosporic fungal reads. We explicitly demonstrate the recurrent dominance of parasitic chytrids during frequent diatom blooms and saprotrophic chytrids during pollen rains. Distinct temporal dynamics of diatom-specific parasitic clades suggest mechanisms of coexistence based on niche differentiation and competitive strategies. The molecular and ecological information on chytrids generated in this study will aid further exploration of their spatial and temporal distribution patterns worldwide. To fully exploit the power of environmental sequencing for studies on chytrid ecology and evolution, we emphasize the need to intensify current isolation efforts of chytrids and integrate taxonomic and autecological data into long-term studies and experiments.</p
The wisdom of networks: A general adaptation and learning mechanism of complex systems: The network core triggers fast responses to known stimuli; innovations require the slow network periphery and are encoded by core-remodeling
I hypothesize that re-occurring prior experience of complex systems mobilizes
a fast response, whose attractor is encoded by their strongly connected network
core. In contrast, responses to novel stimuli are often slow and require the
weakly connected network periphery. Upon repeated stimulus, peripheral network
nodes remodel the network core that encodes the attractor of the new response.
This "core-periphery learning" theory reviews and generalizes the heretofore
fragmented knowledge on attractor formation by neural networks,
periphery-driven innovation and a number of recent reports on the adaptation of
protein, neuronal and social networks. The coreperiphery learning theory may
increase our understanding of signaling, memory formation, information encoding
and decision-making processes. Moreover, the power of network periphery-related
'wisdom of crowds' inventing creative, novel responses indicates that
deliberative democracy is a slow yet efficient learning strategy developed as
the success of a billion-year evolution.Comment: The 2015 preliminary version can be downloaded as an earlier version
of the final paper here. Please find illustrative videos here:
http://networkdecisions.linkgroup.hu and a video abstract here:
https://youtu.be/IIjP7zWGjV
Blowing in the wind: how many roads can a phytoplanktont walk down? A synthesis on phytoplankton biogeography and spatial processes
The selected theme of the 17th Workshop of the International Association for Phytoplankton Taxonomy and Ecology (IAP), ââBiogeography and Spatial Patterns of Biodiversity of Freshwater Phytoplankton,ââ offered the opportunity to explore one
neglected aspect of phytoplankton ecology: the distribution of species in the geographic space. This paper summarizes the outcomes of 20 selected contributions among those presented at the workshop. The articles report the results from studies carried out in five continents (only Oceania is not represented) and on a wide array of aquatic ecosystems (deep and shallow
natural lakes, man-made lakes, temporary and permanent ponds, rivers). The topics analyzed by the contributors are related to Island Biogeography paradigms, dispersal vectors, survival strategies, environmental filters, dispersal distances, vertical and
horizontal spatial variability of phytoplankton between and within water bodies, and of course, invasive algae. The overall analysis of the results presented clearly demonstrates that, as for many others organisms, there are âârulesââ governing freshwater phytoplankton spatial patterns and that these organisms also have a true biogeography, as nowadays is quite evident for several other groups in the same range of size. We can definitively conclude that the statement ââEverything is everywhereââ is obsolete, even though human activities tend to homogenize species distribution in the biosphere
Phytoplankton in extreme environments: importance and consequences of habitat permanency
There is hardly any sunshine exposed surface on this Earth, be it water or terrain, which would not support some biota. Still, many habitats offer harsh conditions requiring specialized physiological adaptations to survive. These environments are referred to as extremes; often inhabited by extremophilic organisms. In this review, characteristic species and assemblage properties of phytoplankton inhabiting extreme environments (especially lakes and pools where planktic life is potentially possible and independently of their origin) in terms of alkalinity, acidity, DOC, salinity, temperature, light and mixing regime will be outlined. Lakes characterized by more than a single extreme are common (e.g. saline + alkaline; acidic + high DOC + high metal content + low light). At the edge of extremes (e.g. pH of 1; salinity over ~ 100â150 g lâ1) single species with appropriate physiological adaptation are selected and the phytoplankton is often dominated by a single species (monodominant) setting compositional diversity to zero. Under less extreme conditions permanent equilibria may persist; in many cases over several years in contrast to âaverageâ lakes where equilibria are rare and ephemeral. Food webs depending on âextreme phytoplanktonâ are often atypical for example because the microbial loop is of prior importance or because birds are top predators
Study of akinetes in the sediments of large European lakes, and hatching experiments to infer long-term colonization dynamics by cyanobacteria
Distinct cyanobacteria belonging to Nostocales have the ability to form resting cells, which provide a mean to persist in harsh environmental conditions. Previous studies carried out in long-sediment cores, showed that akinetes could survive for long-time (up to over 60 years). Studying akinetes in lake sediments may provide a more comprehensive knowledge of past phytoplankton assemblages. The aim of this contribution is to study the colonization history of Nostocales by examining the vertical distribution of akinetes in the sediments of 4 European lakes included in the project EULAKES, namely lakes Garda (oligo-mesotrophic; Italy), Neusiedler (meso-eutrophic; Austria), Balaton (meso-eutrophic; Hungary), and Charzykowskie (eutrophic; Poland). Viability of akinetes was investigated by putting sediment taken from several sections of the core in ASM-1 culture medium at 18° for 16-21 days. The subsequent microscopic examination showed a very low diversity in Lake Garda, with the development of Dolichospermum lemmermannii in the first 10 cm (which correspond to the period since the 1980s). Lake Balaton showed a more diversified group of Nostocales, which included Aphanizomenon cf. gracile, followed by Aphanizomenon issatschenkoi, Aphanizomenon cf. capricorni, and Cylindrospermopsis raciborskii. A. cf. gracile was observed down to ca. 50 cm (>100 yr), whereas A. issatschenkoi and A. cf. capricorni were reported in the more recent sediments and more discontinuously. Anabaena viguieri was a typical representative in Lake Neusiedler down to 50 cm of core sediment (corresponding to the last ca. 60 years), along with Aphanizomenon gracile (in the first 10 cm, around 2000) and some unidentified Anabaena (between 20-60 cm, since early 1900s). In Lake Charzykowskie, the only Nostocales were Anabaena solitaria down to 60 cm of core sediment (late 1940s) along with an unidentified Anabaena sp. The observed differences provide an important platform to interpret the distribution of cyanobacteria in European lakes, which are characterized by different physiographic, climatic and trophic characteristic
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