1,721,085 research outputs found
Cosmopolitism, rareness and endemism in deep-sea marine nematodes
No full textNematodes represent the most abundant benthic metazoan of all seas and oceans, and their relative importance increases with increasing water depth. Understanding the biodiversity patterns of this dominant phylum could be a critical step towards our comprehension of the evolutionary patterns across the largest biome of the biosphere. For instance, it has been assumed for a long time that nematodes are ubiquitous across depths, latitudes and biogeographic regions, but there is still little scientific evidence for this lack of endemism. The present study is based on a meta-analysis of nematode biodiversity data collected from 246 deep-sea sites of the Atlantic Ocean and Mediterranean Sea. We explored the cosmopolitanism, rareness and potential endemism of nematode genera in deep-sea sediments. The results of this analysis indicate that only one-third of nematode families are widely distributed and could potentially be cosmopolitan, whereas 94% of the nematode genera are linked to specific habitats or bathymetric ranges. Singleton nematode genera (i.e. genera presenting as a single individual only in one specific habitat) increased in importance with increasing water depth. We conclude that rareness and endemism may be a far more common feature than previously thought in deep-sea nematode assemblages and hypothesise that the deep ocean interior could be a huge reservoir of endemic nematode species
Structural priming of comprehension in Italian: evidence from relative clause attachment.
No full textNEW RECORD OF THE ALIEN SEAGRASS HALOPHILA STIPULACEA (HYDROCHARITACEAE) IN THE WESTERN MEDITERRANEAN: A FURTHER CLUE TO CHANGING MEDITERRANEAN SEA BIOGEOGRAPHY. (JMBA2 BIODIVERSITY RECORDS)
No full textCase studies using nematode assemblage analysis in aquatic habitats
No full textDanovaro R, Gambi C, Höss S, Mirto S, Traunspurger W, Zullini A. Case studies using nematode assemblage analysis in aquatic habitats. In: Wilson M, Khakouli-Duarte T, eds. Nematodes as environmental bioindicators. Wallingford: CABI; 2009: 146-171
Trophic state, ecosystem efficiency and biodiversity of transitional aquatic ecosystems: analysis of environmental quality based on different benthic indicators
No full textEstuaries and coastal lagoons are characterized by a strong spatial and temporal variability of physicochemical characteristics and productivity patterns. In these environments, the magnitude and direction of the ecological responses to inorganic nutrient increase (i.e. eutrophication) are difficult to predict. In the framework of the project, New Indicators of Trophic state and environmental quality of marine coastal ecosystems and transitional environments (NITIDA), we analysed benthic indicators of trophic state, ecosystem efficiency, and environmental quality in four different transitional environments. The trophic state of the sediments was assessed in terms of quantity and bioavailability of sediment organic C pools; ecosystem efficiency was determined in terms of the prokaryote efficiency in exploiting enzymatycally degraded organic C; environmental quality was determined in terms of meiofaunal diversity. Here, we provide a synopsis of the results obtained and a meta-analysis of the scores assessments obtained using the different ecological indicators of environmental quality and demonstrate that trophic state, ecosystem efficiency, and biodiversity in transitional ecosystems are closely linked. We conclude that the assessment of the environmental quality of transitional ecosystems should be based upon a battery of trophic state indicators and 'sensors' of ecosystem functioning, efficiency, and quality
Trophic conditions and meiofaunal assembalges in the Bari Canyon and the adjacent open slope
No full textDue to their topographic features, submarine canyons are generally sites of intense shelf-slope exchanges of water and material, fuelling the deep basins with large quantities of sediment exiting from the continental shelf. In order to provide new insights about the role of submarine canyons in controlling the relationships between food availability and benthic biodiversity patterns along the continental slope, we investigated the quantity and the biochemical composition of sediment organic matter and the abundance of meiofaunal assemblages in the sediments along two different branches of a canyon and in an adjacent open slope located in the Bari margin (Adriatic Sea). Our results highlight that even twin branches within the same canyon may exhibit very large differences in the quantity, depth-related patterns and biochemical composition of sediment organic matter as well as of meiofaunal abundance. We also report here that the trophic relationships in the canyon sediments are tightly connected with the hydrodynamic conditions and that the steeper and the more flushed the canyon the more hostile environment for the benthos
Short-term impact of clam harvesting on sediment chemistry, benthic microbes and meiofauna in the Goro lagoon (Italy)
No full textThe effects of clam harvesting on sediment organic matter, bacteria, heterotrophic nanoflagellates, ciliates and meiofauna were investigated through a short-term experiment carried out in the Goro lagoon during summer 2000. Sediment samples were collected in two areas: an impacted and an undisturbed (both 25 m2), before and after (5, 24 and 48 h) clam harvesting. Immediately after sediment reworking, total organic matter content decreased for about 20%. Different organic compounds displayed different redeposition patterns resulting in the alteration of the biochemical composition of sediment organic matter. Bacterial abundance decreased significantly after clam harvesting, but microbial enzymatic activities and bacterial C production were relatively unaffected. Heterotrophic nanoflagellates displayed a positive response to sediment disturbance, whereas ciliate and meiofaunal abundance did not display any significant response. Results of this short-term field experiment suggest that clam harvesting determines a positive impact on nutritional availability of sediment organic matter, thus facilitating organic carbon transfer to higher trophic levels of the benthic microbial loop
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