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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
Phytoplankton assemblages in twenty-one Sicilian reservoirs: relationships between species composition and environmental factors
No full textData collected in a limnological survey, carried out between 1987 and 1988 on 21 Sicilian reservoirs of varying trophic state, were ordinated using CANOCO 3.1 to generalise the way in which the structure of phytoplankton assemblage is conditioned by both physical and chemical variables. The results showed that in these man-made lakes, characterised by conspicuouswater-level fluctuations, the annual and interannual variability in the abundance and composition of phytoplankton may be strongly influenced by their peculiar hydraulic regimes rather than by nutrient availability. In particular, it was highlighted that, from the early summer, water abstraction often leads to increased circulation and to the deepening of the mixed layer. In this way, an increase of the ratio of mixing depth to euphotic depth is forced, with the result that phytoplankton cells experience longer periods in darkness as they are carried through the mixed layer. Phytoplankton assemblages change in species composition in response to the environmental variation. Both the raising of the trophic state, with an increase in phytoplankton biomass and a decrease in transparency, and the intensified abstraction enhance the role of light availability in promoting the development of specific phytoplankton assemblages adapted to the modified physical environment. Light climate is an important influence on the species structure of the phytoplankton, especially in the higher part of the trophic gradient. In contrast, the influence of nutrients on the structure of the assemblages appears to be higher in the lower part of the trophic spectrum or in those environments characterised by a higher hydrological stability during the
year
Climate change and enhancement of water-level fluctuations in Mediterranean reservoirs: a sad fate for water quality?
No full textGeneric revision of Cypricercinae McKenzie, 1971 (Crustacea, Ostracoda), with the description of three new genera and one new species and a phylogenetic analysis of the subfamily
No full textThe Cypricercinae are one of the most speciose subfamilies of non-marine ostracods, with more than 170 described species, mostly from the tropics. Although the identity of the subfamily as such is clear, because of the presence of unifying characters such as the Triebel’s loop in the attachment of the caudal ramus, the supra-specific taxonomy of this group has long been confused because of lack of good generic and tribal characters. Here, the generic characters of the Cypricercinae are revised. Eleven genera are retained in this subfamily, including three new genera: Bradleytriebella n. gen., Nealecypris n. gen.
and Pseudostrandesia n. gen. Tanycypris siamensis n. sp. is described from Thailand. In addition, five species [Bradleystrandesia fuscata (Jurine, 1820), Bradleytriebella tuberculata (Hartmann, 1964), Nealecypris obtusa (Klie, 1933), Pseudostrandesia striatoreticulata (Klie, 1932), Spirocypris horrida (Sars, 1926)] are redescribed. A key to the genera is given. We propose three tribes: the nominal tribe Cypricercini McKenzie, 1971, as well as two new tribes, Bradleystrandesiini n. trib. and Nealecypridini n. trib. To evaluate the systematic relationships within this subfamily, phylogenetic analyses, based on morphological characters of valves and soft parts, were conducted. The Neighbour Joining (NJ) tree strongly supports the classification into three independent tribes, whereas the Maximum Parsimony (MP) tree shows that Bradleystrandesiini n. trib. is actually a subgroup of the Cypricercini
Morphological analysis of phytoplankton as a tool to assess ecological state of aquatic ecosystems: The case of Lake Arancio, Sicily, Italy
Get PDFPhytoplankton requires a sufficient supply of light and nutrients to grow. At the same time it is largely entrained in water motion and is subject to grazing from planktonic herbivores. The pelagic life of lake phytoplankton is based on 4 pillars: living in suspension, light harvesting, nutrient uptake, and escape from grazing. Environmental variability and the uneven distribution of resources among and within the different aquatic ecosystems exert a selective pressure on these organisms, which are formed by a single cell or by colonies with either relatively low or high numbers of cells. Phytoplankton displays an amazing morphological variability representing an adaptation to spatial and temporal variability of their environments. Among functional traits of phytoplankton, morphological features such as shape and size represent an unavoidable starting point to fully understand the relationships between this group of organisms and its environment. The molding effect of environmental variables on phytoplankton morphology is particularly evident in highly dynamic environments such as reservoirs or ponds. The analysis of phytoplankton morphology can thus supply important information on the ecological conditions of a given waterbody. To support this hypothesis, data are presented on the main morphological features of phytoplankton from a 20-year limnological investigation carried out in a Mediterranean man-made lake. The results show that phytoplankton morphological variability reflects different environmental scenarios, and that the morphological features of phytoplankton represent a powerful tool to assess the ecological or trophic state of aquatic ecosystems. © International Society of Limnology 2013.Phytoplankton requires a sufficient supply of light and nutrients to grow. At the same time it is largely entrained in water motion and is subject to grazing from planktonic herbivores. The pelagic life of lake phytoplankton is based on 4 pillars: living in suspension, light harvesting, nutrient uptake, and escape from grazing. Environmental variability and the uneven distribution of resources among and within the different aquatic ecosystems exert a selective pressure on these organisms, which are formed by a single cell or by colonies with either relatively low or high numbers of cells. Phytoplankton displays an amazing morphological variability representing an adaptation to spatial and temporal variability of their environments. Among functional traits of phytoplankton, morphological features such as shape and size represent an unavoidable starting point to fully understand the relationships between this group of organisms and its environment. The molding effect of environmental variables on phytoplankton morphology is particularly evident in highly dynamic environments such as reservoirs or ponds. The analysis of phytoplankton morphology can thus supply important information on the ecological conditions of a given waterbody. To support this hypothesis, data are presented on the main morphological features of phytoplankton from a 20-year limnological investigation carried out in a Mediterranean man-made lake. The results show that phytoplankton morphological variability reflects different environmental scenarios, and that the morphological features of phytoplankton represent a powerful tool to assess the ecological or trophic state of aquatic ecosystems
Effects of ultraviolet radiation on productivity and nitrogen fixation in the Cyanobacterium, Anabaena sp. (Newton's strain)
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La legislazione emergenziale si è dimenticata dell'arbitrato?
No full textThis paper, prompted from the decision taken by the Arbitration Council of Monza on April 15, 2020, addresses the crucial issue of the postponement of hearings as well as the suspension of procedural time-limits hereto related in the arbitration process, during the lockdown phase in Italy
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