1,721,097 research outputs found
Phytoplankton in extreme environments: importance and consequences of habitat permanency
Get PDFThere 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 ~ 100–150 g l−1) 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 „average” lakes where equilibria are rare and ephemeral. Food webs depending on „extreme phytoplankton” are often atypical for example because the microbial loop is of prior importance or because birds are top predators
Different invasibility of permanent and temporary waterbodies in a semiarid Mediterranean Island
Get PDFNonindigenous species (NIS) represent a threat to aquatic biodiversity worldwide. However, freshwater ecosystems in drylands are potentially more prone to biological invasions than those located in temperate regions because of the higher number of artificial waterbodies generally occurring in these areas, which might act as invasion hubs for NIS. We review the available information about NIS in Sicilian waterbodies, discuss the role exerted by artificial lakes and ponds in facilitating the establishment of NIS in arid and semiarid areas, and compare the invasibility of permanent and temporary waterbodies in drylands. Artificial waterbodies increase the target-area effect for dispersers and provide a hospitable environment for NIS because of their recent origin and the lack of efficient biological filters against newcomers, thus acting as bridgeheads and invasion hubs favouring invasive species. Finally, we propose actions to attenuate the threats caused by NIS to the sensitive native biota of aquatic ecosystems in drylands
Life in suspension and its impact on phytoplankton morphology: an homage to Colin S. Reynolds
Get PDFThe amazing morphological diversity of phytoplankton has to be considered an evolutionarily driven compendium of strategies to cope with the strong variability and unpredictability of the pelagic environment. Phytoplankton collects unicellular and colonial photosynthetic organisms adapted to live in apparent suspension in turbulent water masses. Turbulence represents a key driver of phytoplankton dynamics in all aquatic ecosystems and phytoplankton morphological variability is the evolutionary response of this group of photosynthetic organisms to the temporal and spatial scales of variability of turbulence. This paper reviews the existing literature on the effects exerted by turbulence on phytoplankton populations and is aimed at showing how deeply turbulence contributes to the shape and size structure of phytoplankton assemblages. Our aim is to explore how turbulence governs phytoplankton access to resources and, at the same time, how the shape and size structure of phytoplankton represent the evolutionary way in which this group of organisms has optimised its survival in the highly dynamic aquatic environment. The paper is intended to serve as an homage to the (phytoplankton) ecologist Colin S. Reynolds. His life-long work highlighted how profoundly the ecology of phytoplankton depends on the physical constraints governing the movements of the water masses in which phytoplankton evolved and lives
Laghi artificiali dell’Italia meridionale e Isole maggiori
No full textIn questo articolo gli autori analizzano i principali fattori ecologici che determinano il funzionamento dei laghi artificiali localizzati nel meridione d’Italia e nelle isole maggiori. In particolare, viene illustrato come il ciclo idrologico annuale di questi ecosistemi sia fortemente influenzato dalle attività umane connesse all’uso dell’acqua invasata. Tali attività spesso interferiscono negativamente con la dinamica dei fattori fisici (stratificazione/circolazione), chimici (concentrazioni di nutrienti e ossigeno) e biologici (successione stagionale del fitoplancton) che governano il funzionamento di questi ecosistemi. Comprendere come il cambiamento climatico in atto influenzi il ciclo idrologico, sia quello naturale sia quello alterato dalle attività umane, è fondamentale per assicurare una gestione oculata e consapevole dei laghi artificiali volta a minimizzare gli eventuali effetti negativi che una ridotta disponibilità idrica e un aumento delle temperature medie annuali possono esercitare sulla qualità delle acque invasate e, più in generale, sui servizi ecosistemici cui provvedono i laghi artificiali.In this paper the authors analyze the main factors driving the ecological functioning of man-made lakes located in the southern part of Italy and in its main islands. The annual hydrological cycle of these ecosystems is strongly influenced by human activities which often negatively interfere with the dynamics of physical (stratification/circulation patterns), chemical (nutrients and oxygen availability) and biological (seasonal succession of phytoplankton) factors. Understanding how the climate change influences the hydrological cycle, both in natural and human-altered conditions, is of paramount importance to warrant a sound management of man-made lakes, addressed toward minimizing the negative effects exerted by a reduced water availability and the increased annual temperatures on the quality of the stored waters and on the ecosystem services provided by man-made lakes
On the occurrence and distribution of Calanipeda aquaedulcis Kritschagin, 1873 (Copepoda, Calanoida, Pseudodiaptomidae) in Sicily, Italy, with some notes on coexistence and species replacement in calanoid copepods
Get PDFThe only population of the pseudodiaptomid copepod Calanipeda aquaedulcis Kritschagin, 1873 to date reported to occur in Sicily disappeared at the beginning of the XXI century due to deep environmental changes which affected the single site (Lake Biviere di Gela) known for this species on the island. In that site C. aquaedulcis is now replaced by Copidodiaptomus numidicus (Gurney, 1909), a diaptomid copepod whose distribution has been greatly increasing since the second half of the last century. In the present note, the occurrence of C. aquaedulcis in 12 novel water bodies spread throughout Sicily is reported, and some environmental data on the sites where the species was collected are provided. Moreover, in a few sites C. aquaedulcis was found to co-occur with Copidodiaptomus numidicus. The recorded co-occurrence of these two species and the replacement of C. aquaedulcis with C. numidicus in Lake Biviere di Gela are briefly discussed
Santa Rosalia, the icon of biodiversity
No full textThis article summarizes the results presented
in a series of invited contributions which were submitted to celebrate the fiftieth anniversary of publication of the seminal article ‘‘Homage to Santa Rosalia or why are there so many kinds of animals’’ by G.E. Hutchinson. The authors were asked to explore
old and new paradigms of biodiversity in aquatic ecosystems. The contributions by Hutchinson in this field are truly landmarks in the history of modern ecological sciences. The authors of the contributed articles, stimulated by one of the most fruitful concept articles in ecology that has appeared over the last half century, have shown that scientific investigation, although still seeking the causes underlying diversity maintenance, is moving toward (i) the understanding of the functions and mechanisms of diversity in ecosystems and (ii) the evaluation of the role of a diversified assemblage in ensuring the integrity of ecosystem service
On Daphnia (Ctenodaphnia) similis Claus, 1876 and other interesting anomopods (Crustacea, Branchiopoda) from Apulia (Southern Italy)
Get PDFThe presence of Daphnia species in Apulia (southern Italy) freshwaters is update
Functional classifications in phytoplankton ecology: a comparative review of approaches and experiences
Get PDFEmpirical 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 & Padisák, 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
Preface: phytoplankton responses to human impacts at different scales
Get PDFThis book: Deals with eutrophication impact on ecosystem functioning with a different focus and broader perspective.
Takes into account the effects of multiple stressors on microalgal assemblages. Includes specific contributions on the autoecology and taxonomy of dinoflagellates and cyanobacteria.
Features examples of applications of the morphology-, morpho-functional and functional groups (FG), (MFG) and (MBFG)
Phytoplankton responses to human impact at different scales provides a state-of-the-art review of changes in the phytoplankton assemblages determined by human alterations of lakes and rivers. A wide spectrum of case studies describe the effects due to eutrophication and climate change, as well as other impacts connected with watershed management, hydrological alterations and introduction of non-indigenous species. The volume also includes two wide reviews on planktonic coccoid green algae and planktic heterocytous cyanobacteria. This book is addressed to ecologists and scientists involved in phytoplankton ecology and taxonomy. Many case studies provide a sound scientific basis of knowledge for a wise management of water bodies
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