1,721,070 research outputs found
Parasitism and host behavior in the context of a changing environment: The Holocene record of the commercially important bivalve Chamelea gallina, northern Italy
Full text linkRapid warming and sea-level rise are predicted to be major driving forces in shaping coastal ecosystems and their services in the next century. Though forecasts of the multiple and complex effects of temperature and sea-level rise on ecological interactions suggest negative impacts on parasite diversity, the effect of long term climate change on parasite dynamics is complex and unresolved. Digenean trematodes are complex life cycle parasites that can induce characteristic traces on their bivalve hosts and hold potential to infer parasite host-dynamics through time and space. Previous work has demonstrated a consistent association between sea level rise and increasing prevalence of trematode traces, but a number of fundamental questions remain unanswered about this paleoecological proxy. Here we examine the relationships of host size, shape, and functional morphology with parasite prevalence and abundance, how parasites are distributed across hosts, and how all of these relationships vary through time, using the bivalve Chamelea gallina from a Holocene shallow marine succession in the Po coastal plain. Trematode prevalence increased and decreased in association with the transition from a wave-influenced estuarine system to a wave-dominated deltaic setting. Prevalence and abundance of trematode pits are associated with large host body size, reflecting ontogenetic accumulation of parasites, but temporal trends in median host size do not explain prevalence trends. Ongoing work will test the roles of temperature, salinity, and nutrient availability on trematode parasitism. Parasitized bivalves in one sample were shallower burrowers than their non-parasitized counterparts, suggesting that hosts of trematodes can be more susceptible to their predators, though the effect is ephemeral. Like in living parasite-host systems, trematode-induced malformations are strongly aggregated among hosts, wherein most host individuals harbor very few parasites while a few hosts have many. We interpret trace aggregation to support the assumption that traces are a reliable proxy for trematode parasitism in the fossil record
Il controllo del dolore in oncologia pediatrica.La giocoterapia come tecnica non farmacologica
No full textL'efficacia della comunicazione come presupposto per l'alleanza terapeutica : un'indagine conoscitiva in oncologia pediatrica
No full textImpact of sedimentation, climate and sea level on marine sedimentary pyrite sulfur isotopes: Insights from the Valle di Manche section (Lower-Middle Pleistocene, southern Italy)
Full text linkVariations in the isotopic composition of sulfur in sedimentary pyrite (δ34Spyr) are often used to reconstruct global sulfur biogeochemical cycling and Earth's surface oxidation state over Earth history. Recent work, however, has shown that δ34Spyr is strongly impacted by local depositional conditions, which both confounds attempts to reconstruct global sulfur cycling and provides a new proxy for investigating local paleoenvironmental conditions. We present a chemostratigraphic record of δ34Spyr in a detailed paleoenvironmental and sequence stratigraphic framework spanning the Early-Mid Pleistocene transition from the Crotone Basin (Calabria, Southern Italy). Bulk δ34Spyr data parallel transgressive-regressive cycles and enable the differentiation of progradational and retrogradational stacking patterns, where δ34Spyr values decrease toward −50‰ in outer shelf deposits during late transgression and become more positive and variable in prograding sedimentary units accumulated in shallower environments. In parallel with the observed variations in δ34Spyr, complementary data on organic carbon abundance and isotopic composition and total nitrogen abundance document changes in terrestrial delivery of sediment to the basin, as a consequence of glacial-interglacial eustatic sea-level changes, regional climate and local tectonics. The chemostratigraphic record of δ34Spyr appears sensitive to variations in sedimentation rates and local erosional surfaces and therefore may represent a powerful tool to assess stratal stacking patterns for sequence stratigraphic interpretations of siliciclastic successions. These results highlight the role of local conditions in controlling sedimentary δ34Spyr records and illustrate how isotopic data can be used to reconstruct key parameters of the sedimentary environment that might not otherwise be accessible, especially in deep-time strata
Mid-Late Pleistocene Neanderthal landscapes in southern Italy: Paleoecological contributions of the avian assemblage from Grotta del Cavallo, Apulia, southern Italy
Full text linkWe present a detailed paleoecologic analysis of avian assemblages from the Mousterian layers of the Middle Paleolithic Grotta del Cavallo site in southern Italy. Findings improve knowledge of the landscape that was exploited by Neanderthals. During the MIS 7, 6 and 3, the cave was surrounded by extensive grasslands and shrublands, locally interspersed by open woodland and rocky outcrops, whereas the coastal plain (currently underwater) hosted wetlands. Water bird taxa show an increase in population size during the cool-temperate climatic interval attributed to MIS 3, possibly linked to more humid conditions or a shorter distance between the wetland settings and the cave, compared to the previous glacial phase (MIS 6). In addition, coverage-based rarefied richness suggests higher avian diversity during MIS 3, which may reflect greater landscape heterogeneity due to the presence of wetland habitats. The tentative discovery of Branta leucopsis, together with several bird species currently found at higher altitudes, reinforces geochemically-derived palaeoclimate inferences of cooler than the present conditions. These assemblages also include the first fossil occurrence of Larus genei worldwide, the first Italian occurrence of Emberiza calandra, the oldest Italian occurrence of Podiceps nigricollis, and the occurrence of the rarely reported Sylvia cf. communis. Taphonomic analyses indicate that bone modifications are mainly due to physical syn- and post-depositional processes, and that the assemblage mainly accumulated through short-range physical transport and the feeding activities of nocturnal raptors
A multidisciplinary study of ecosystem evolution through early Pleistocene climate change from the marine Arda River section, Italy
No full textThe Arda River marine succession (Italy) is an excellent site to apply an integrated approach to paleoenvironmental reconstructions, combining the results of sedimentology, body fossil paleontology, and ichnology to unravel the sedimentary evolution of a complex marine setting in the frame of early Pleistocene climate change and tectonic activity. The succession represents a subaqueous extension of a fluvial system, originated during phases of advance of fan deltas affected by high-density flows triggered by river floods, and overlain by continental conglomerates, indicating a relative sea level fall and the establishment of a continental environment. An overall regressive trend is observed through the section, from prodelta to delta front and intertidal settings. The hydrodynamic energy and the sedimentation rate are not constant through the section, but they are influenced by hyperpycnal flows, whose sediments were mainly supplied by an increase in Apennine uplift and erosion, especially after 1.80 Ma. The Arda section documents the same evolutionary history of coeval successions in the Paleo-Adriatic region, as well as the climatic changes of the early Pleistocene. The different approaches used complement quite well one another, giving strength and robustness to the obtained results
- …
