A reassessment of the origin and distribution of the subterranean genus Pseudolimnocythere Klie, 1938 (Ostracoda, Loxoconchidae), with description of two new species from Italy

Groundwater ecosystems host a rich and unique, but still largely unexplored and undescribed, biodiversity. Several lineages of ostracod crustaceans have subterranean representatives or are exclusively living in groundwaters. The stygobitic genus Pseudolimnocythere Klie, 1938 has a West Palearctic distribution, and includes few living and fossil species of marine origin. Through a comprehensive literature review and the description of the two new living species, Pseudolimnocythere abdita sp. nov. and Pseudolimnocythere sofiae sp. nov., from springs in the Northern Apennines, Italy, a morphological analysis was carried out with the aim of comparing the valve morphology of living and fossil species, and to discuss previous hypotheses about time and mode of colonization of inland waters. Pseudolimnocythere species show a low variability in valve morphology, with a remarkable stasis over geological times. The distribution of extant and fossil species is consistent with a scenario of multiple and independent events of colonization of continental habitats linked to sea level variations starting from Middle Miocene in the Paratethys and, later, in the Mediterranean. The most common colonization routes of inland waters have taken place through karst formations along ancient coastlines, although we cannot exclude some minor active migration through the hyporheic zone of streams. Available distribution data suggest a poor dispersal ability of Pseudolimnocythere species after they had colonized continental waters

Trophic state and seasonal dynamics of phytoplankton communities in two sand-pit lakes at different successional stages

The seasonal and inter-annual dynamics of phytoplankton in two Italian sand-pit lakes have been analysed over three years (2004-2006). The studied lakes, Ca' Morta (CM) and Ca' Stanga (CS), have a common origin and are contiguous, but are of different ages and have been managed in different ways. CM was created in 2002 and was still being dredged during the study period, while sand quarrying in CS began in 1998 and ended at the beginning of the study period. These conditions were thought to be of particular interest in assessing the influence of dredging activities on algal assemblages. Physical and chemical water parameters were also analysed to characterise the two lakes and investigate the effects of hydro-chemical features on phytoplankton. CS was stratified from April to October each year during the study period, while CM showed weaker thermal stratification. Conductivity, dissolved nitrate and dissolved reactive silica concentrations were greater in CM than in CS. The mixing depth/euphotic depth ratio was also higher in CM, probably because of water column mixing induced by hydraulic dredging. Overall, 185 phytoplankton taxa were found, of which ca 50% were present in both lakes. No significant differences in species richness were observed between lakes, but the decreasing trend of Simpson index values measured in CS showed a reduction in biodiversity after the excavation phase. Phytoplankton biomass was higher in CS than in CM, the latter being oligo-mesotrophic and the former mesotrophic. Diatoms and dinoflagellates were the dominant taxa in both lakes. The main differences in phytoplankton assemblages were related to the persistence of chryptophytes and chlorophytes in CM. Multivariate analyses support the hypothesis that different thermal patterns induced by dredging activities, along with certain physico-chemical parameters of the water, were the major factors shaping phytoplankton communities

The Recent non-marine ostracods of Tunisia: an updated checklist with remarks on their regional distribution patterns and ecological preferences

Different lines of investigation have recently contributed to increasing the available knowledge about the invertebrates inhabiting inland waters of north Africa, but a comprehensive synopsis on Tunisian Ostracoda is missing to date. An updated checklist of Recent non-marine ostracods from Tunisia and data on their distribution is thus offered here, representing the most extensive survey on this crustacean group ever carried out in inland waters throughout the country. One-hundred-five sites covering various climate zones, from Mediterranean to desert areas, were sampled between 2002 and 2012. Most of the considered water bodies were temporary or ephemeral habitats, but a few permanent sites were sampled as well. Overall, 18 genera and 32 taxa of putative species rank were collected in the frame of this survey, among which nine species and five genera were new to Tunisian fauna. As a result of this study and based on previous investigations, nine families (Candonidae, Cyprididae, Cytherideidae, Darwinulidae, Ilyocyprididae, Leptocytheridae, Limnocytheridae, Loxoconchidae, Paradoxostomatidae), 29 genera and at least 45 species of non-marine ostracods are currently known for Tunisia, which thus prove to host the most diverse ostracod fauna among north African countries. The number of species occurring in a single sample varied from 1 to 4. The Eucypris virens complex was the most widespread taxon (58 records), followed by Heterocypris barbara (30 records), Heterocypris incongruens (22 records), and Sarscypridopsis aculeata (16 records). For some ostracod species, clear distributional gradients associated with different climatic conditions were observed. The affinities with adjacent Maghrebian ostracod faunas are discussed. This study confirms the crucial role played by marginal aquatic habitats for the conservation of biodiversity, in particular in arid and semi-arid regions

An updated checklist of Recent ostracods (Crustacea: Ostracoda) from inland waters of Sicily and adjacent small islands with notes on their distribution and ecology

Because of its position in the middle of the Mediterranea Sea and a complex geological history that has promoted repeated waves of biological colonization, Sicily (Southern Italy) is of particular interest from a biogeographical perspective. A number of previous investigations, dating back as far as the end of the 19th century, have contributed to gather information about the occurrence of Recent non-marine ostracods in Sicily, making this region one of the most intensively studied areas of the Central Mediterranean. Published data on ostracod distributions have been integrated through an extensive field survey on mainland Sicily and surrounding small islands and archipelagos. Altogether, 271 ostracod samples and 11 sediment samples from dry water bodies were analysed from 218 sites visited between 2002 and 2017. Sampling sites were selected to encompass all the most common types of freshwater aquatic habitats, both natural and artificial, present in the area. Thirty-nine ostracods were identified at species level and 12 at supraspecific level. The present study reports four species (Cypria subsalsa, Eucypris mareotica, Physocypria kerkyrensis, Vestalenula boteai) and one genus (Vestalenula) as new for both peninsular Italy and adjacent islands, and three species (Candonopsis novaezelandiae, Ilyocypris inermis, Neglecandona neglecta) and two genera (Candonopsis and Physocypria) as new for Sicily. The updated checklist of the study area now includes at least 46 nominal species and other taxa identified at supraspecific level, belonging to 28 genera in 8 families (Candonidae, Cyprididae, Cytherideidae, Darwinulidae, Hemicytheridae, Ilyocyprididae, Limnocytheridae and Notodromadidae). The present investigation represents a significant addition to the knowledge of the ostracod diversity and distribution in the Sicilian area and in Italy as a whole. It also provides a sound baseline data for further comparative faunal studies aimed at investigating the affinities and origins of the central Mediterranean inland-water ostracod faunas, and to analyse their biogeographic patterns

Flow network indices signal a directional change in ecosystems: Evidence from a small mountain lake (Lake Santo, northern Italy)

Empirical evidence of the theoretically expected trends of ecosystem development is scarce so far. In this research, we used long-term empirical data about the plankton community of a small mountain lake (Lake Santo, northern Apennines, Italy) to reconstruct its developmental trajectory during a period comprised between early 1970 s and 2010 s. We exploited these data to build yearly ecological networks and from their configuration of energy flows we computed network information indices. The trends of these indices enlighten about the developmental trajectory of this ecosystem during the period covered by the data set. In particular, they indicate that Lake Santo evolved in the direction of increasing stability at the expense of efficiency in energy transfer. We compared these results with current hypotheses about the directionality of ecosystem development, which are rooted in ecosystem theory, and discussed the possibility that, counter to some theoretical models of ecosystem development, Lake Santo followed an unimpeded direction of development rather than a trajectory typical of an ecosystem under stress. Finally, the long-term trends of flow network indices provided insights about the health status of the ecosystem

Variability in Environmental Conditions Strongly Impacts Ostracod Assemblages of Lowland Springs in a Heavily Anthropized Area

The Po river plain (Northern Italy) hosts artificial, lowland springs locally known as fontanili, which provide important ecosystem services in an area dominated by intensive agricultural activities. Here we present a study carried out in 50 springs. Each spring was visited once from October 2015 to January 2016. The sampled sites were selected to include springs studied in 2001 and 2004, to evaluate changes in water quality and ostracod assemblages that possibly occurred over a period of 10–15 years, and explore the relationships between ostracod community composition and water physical and chemical variables. Our results showed a decrease in the chemical water quality especially, in springs south of the Po river, evidenced by high nitrate levels. Most of the studied springs showed a relevant decrease in dissolved reactive silica, probably related to recent transformations of either agricultural practices or crop typology. Ostracods were mostly represented by common and tolerant species, and communities were characterized by low alpha diversity and high species turnover. Water temperature and mineralization level were the most influential variables in structuring the ostracod communities. We stress the need to implement conservation and restoration measures for these threatened ecosystems, to regain their role as ecosystem services providers

The new checklist of the Italian Fauna: Rotifera

5openInternationalInternational coauthor/editorWe present a data set reporting the checklist of the species of the phylum Rotifera for Italy, updating the one previously published in the series ‘Checklist delle Specie della Fauna d'Italia’ in 1995. The records of the updated checklist refer to the 483 taxa at the species and subspecies level currently known from national Italian territories (119 Bdelloidea, 362 Monogononta, 2 Seisonacea) at the regional level (22 terrestrial and nine marine geographical units). The records refer to various freshwater, limno-terrestrial, and marine coastal habitats. The previous checklist reported 245 taxa (54 Bdelloidea, 189 Monogononta, 2 Seisonacea): three taxa were removed because currently considered not valid and 241 were added,scanning 21 papers we found that were published between 1993 and 2020, expanding the regional records and including four papers older than 1993 with overlooked records in the previous checklist. The Rotifera data are part of the updated Checklist of the Italian Fauna, which is viewable on the LifeWatch Italy platform at https://www.lifewatchitaly.eu/en/initiatives/checklist-fauna-italia-en/checklist and is freely available on the LifeWatch Italy Data Portal (https://dataportal.lifewatchitaly.eu/data). The checklist will be dynamically updated with new records; this paper describes the state of the art of the data set regarding Rotifera on May 2021.openFontaneto, D.; Bertani, I.; Cancellario, T.; Rossetti, G.; Obertegger, U.Fontaneto, D.; Bertani, I.; Cancellario, T.; Rossetti, G.; Obertegger, U

Effect of environmental stress on clonal structure of Eucypris virens (Crustacea, Ostracoda)

Environmental stress imposes strong natural selection on clonal populations, promoting evolutionary change in clonal structure. Environmental stress may also lead to reduction in population size, which together with clonal selection may reduce genotypic diversity of the local populations. We examined how clonal structure in wild-collected samples of two parthenogenetic populations of the freshwater ostracod Eucypris virens responded to hypersalinity and starvation, and the combination of the two stressors. We applied the stress treatments in a factorial design for one generation. When 60% of the individuals per experimental unit had died, post-experimental clonal structure was compared to that of the start of the experiment, which reflected the field conditions. We used five polymorphic allozyme loci as genotype markers. All stress treatments reduced survival compared to the control treatment. In the population "Rivalazzetto”, we observed a reduction of clonal richness in the control treatment, with the initially dominant clone maintaining dominance. This may have resulted from interclonal competition and clone-specific survival under the different laboratory conditions. Clonal richness remained high in the salinity treatment while it was reduced in the combined stress and starvation treatments. In the population "Fornovo”, clonal richness reduced in all treatments including control, while the salinity and combined stress treatment reduced clonal evenness. The clone dominating at the start of the experiment increased in frequency in all treatments, but the change in clonal structure during the experiment was more pronounced in this population. These results suggest that in some conditions an intermediate level of environmental stress may lessen the decline in genetic diversity by strong inter-clonal competition. Moreover, the variation in clonal structure among the stress treatments and distinct genetic backgrounds indicates that more general predictions of stress effects on clonal structure may be difficul

Dynamics of sexual and parthenogenetic populations of Eucypris virens (Crustacea: Ostracoda) in three temporary ponds

Eucyprisvirens is a freshwater ostracod in which both sexual reproduction and parthenogenesis occur. Sympatric coexistence of both reproductive modes is known in zones of overlap. This renders the species a potentially valuable model organism to study the ‘queen of evolutionary problems', i.e. why sex is so successful despite its costs (paradox of sex). In order to maximally exploit this potential, a broad knowledge of the species' ecology is essential, including an understanding of its life history and population dynamics. Here, the phenology of the species was followed in three temporary ponds through monthly (Spain) or fortnightly (Poland) samplings, throughout an inundation period. This study confirms the wide ecological tolerances of E.virens. Although the species is generally assumed to be univoltine, two hatching periods were observed in the Spanish sites. Biotic interactions, especially predation, appear to be the important determinants of population dynamics in long-hydroperiod sites. Abiotic conditions may influence population dynamics through their impact on egg hatching. In the site with male presence, the initially female-biased sex ratio evolved towards a balanced sex ratio through the season. No consistent differences in limb morphology were observed between females originating from the three study sites. On the other hand, valve size of adult females varied among sites, possibly influenced by local environmental conditions (mainly salinity and pH) as well as the expected genetic diversit

Flow network indices signal a directional change in ecosystems: Evidence from a small mountain lake (Lake Santo, northern Italy)

Highlights: • Flow network indices signal directional changes during ecosystem development. • They showed linear trends in the evolution of a mountain lake. • The lake evolved to increase stability at the expense of efficiency in energy transfer. • Trends of the indices challenge current hypotheses about the directionality of ecosystem development. • Flow network indices from long term field data can help assessing ecosystem health. Empirical evidence of the theoretically expected trends of ecosystem development is scarce so far. In this research, we used long-term empirical data about the plankton community of a small mountain lake (Lake Santo, northern Apennines, Italy) to reconstruct its developmental trajectory during a period comprised between early 1970 s and 2010 s. We exploited these data to build yearly ecological networks and from their configuration of energy flows we computed network information indices. The trends of these indices enlighten about the developmental trajectory of this ecosystem during the period covered by the data set. In particular, they indicate that Lake Santo evolved in the direction of increasing stability at the expense of efficiency in energy transfer. We compared these results with current hypotheses about the directionality of ecosystem development, which are rooted in ecosystem theory, and discussed the possibility that, counter to some theoretical models of ecosystem development, Lake Santo followed an unimpeded direction of development rather than a trajectory typical of an ecosystem under stress. Finally, the long-term trends of flow network indices provided insights about the health status of the ecosystem