scholarly journals Comparative Analysis of Mollusc Assemblages from Different Hard Bottom Habitats in the Central Tyrrhenian Sea

Diversity ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 74 ◽  
Author(s):  
Edoardo Casoli ◽  
Andrea Bonifazi ◽  
Giandomenico Ardizzone ◽  
Maria Flavia Gravina ◽  
Giovanni Fulvio Russo ◽  
...  
Keyword(s):  
Trophic Structure ◽  
Multivariate Analyses ◽  
Distribution Patterns ◽  
The Other ◽  
Tyrrhenian Sea ◽  
Coastal Zones ◽  
Habitat Differences ◽  
Molluscan Fauna ◽  
Mollusc Assemblages ◽  
Taxonomic Groups

Composition, trophic structure, and species-substrate relationships of molluscan assemblages inhabiting different hard bottom habitats (Sabellaria alveolata reef, photophilic bottoms, Phyllophora crispa sciaphilic assemblage, and coralligenous bioconstruction) were studied in two different sites of the Tyrrhenian Sea. In particular, molluscs from the Sabellaria alvevolata (Linnaeus, 1767) reef and coralligenous concretion were investigated, testing the hypothesis that bioconstructions increase the diversity and abundance of associated biota compared to the surrounding habitats. A total of 3134 individuals belonging to the classes of Polyplacophora (5 species, 24 individuals), Bivalvia (39 sp., 2734 ind.), and Gastropoda (53 sp., 376 ind.) were identified. These three taxonomic groups showed different distribution patterns in the studied habitats. Multivariate analyses revealed significant inter-habitat differences in the composition of mollusc assemblages, especially between bioconstructions and the other habitats. S. alveolata and coralligenous host the highest rich molluscan fauna when compared to the neighboring hard bottom habitats characterized by photophilic and sciaphilic assemblages. The first ones were dominated by bivalve suspension feeders, mainly represented by sessile and sedentary organisms, which act as bio-constructors, bio-eroders, or simply inhabit the several microhabitats provided by the bioconstructions, while the second ones host a rich molluscan fauna dominated by gastropod grazers and predators. The present study increases the comparative knowledge of molluscan assemblages inhabiting habitats of littoral plans of the Mediterranean Sea, providing pivotal information regarding biodiversity of coastal zones.

Distribution patterns and population structure of Illex coindetii (Cephalopoda: Ommastrephidae) in the Southern Tyrrhenian Sea: Historical series of 14 years trawl survey

2011 ◽  
Vol 109 (2-3) ◽  
pp. 342-350 ◽  
Author(s):  
Anna Perdichizzi ◽  
Laura Pirrera ◽  
Daniela Giordano ◽  
Francesco Perdichizzi ◽  
Barbara Busalacchi ◽  
...  
Keyword(s):  
Population Structure ◽  
Distribution Patterns ◽  
Trawl Survey ◽  
Tyrrhenian Sea ◽  
Historical Series ◽  
Southern Tyrrhenian Sea

scholarly journals Common environmental descriptors of two benthic amphi-atlantic mollusc assemblages

2006 ◽  
Vol 54 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Ricardo S. Absalão ◽  
J. Moreira ◽  
Jesus S. Troncoso
Keyword(s):  
Rio De Janeiro ◽  
Environmental Data ◽  
Multiple Discriminant Analysis ◽  
Medium Sand ◽  
Sediment Grain Size ◽  
Environmental Space ◽  
Macro Scale ◽  
Molluscan Fauna ◽  
Mollusc Assemblages ◽  
Sandy Sediments

Two benthic mollusc assemblages of the continental shelf on both sides of the Atlantic Ocean, a tropical one in Rio de Janeiro, Brazil, and another, temperate, in Galicia, Spain were investigated, with a view to finding common environmental descriptors which would explain, on a macro-scale, why these assemblages are there. Both of the assemblages concerned show approximately the same species richness, about 150 taxa each. The molluscan fauna of both regions live on sandy sediments. The Galician assemblages are at about 2-12 m depth, while those in Rio de Janeiro are at about 10-40 m depth. Malacological assemblages were defined through Cluster Analysis and Multiple Discriminant Analysis of the environmental data showed that each assemblage has its own environmental space. These assemblages have no species in common, but show the same phenological characters associated with each sedimentological facies. The same set of environmental variables (median sediment grain size, skewness, kurtosis, sorting, fine and medium sand fractions and depth) were selected as controlling these assemblages, suggesting that they play their role as general environmental descriptors.

scholarly journals Tracers confirm downward mixing of Tyrrhenian Sea upper waters associated with the Eastern Mediterranean Transient

2010 ◽  
Vol 7 (4) ◽  
pp. 1533-1557
Author(s):  
W. Roether ◽  
J. E. Lupton
Keyword(s):  
Deep Water ◽  
Time Scale ◽  
Eastern Mediterranean ◽  
Western Mediterranean ◽  
The Other ◽  
Tyrrhenian Sea ◽  
Convective Mixing ◽  
Deep Waters ◽  
Major Process ◽  
Gibraltar Strait

Abstract. Observations of tritium and 3He in the Tyrrhenian Sea, 1987–2009, confirm the enhanced convective mixing of intermediate waters into the deep waters that has been noted and associated with the Eastern Mediterranean Transient in previous studies. Our evidence for the mixing rests on increasing tracer concentrations in the Tyrrhenian deep waters, accompanied by decreases in the upper waters, which are supplied from the Eastern Mediterranean. The downward transfer is particularly evident between 1987 and 1997. Later on, information partly rests on increasing tritium-3He ages; here we correct the observed 3He for contributions released from the ocean floor. The Tyrrhenian tracer distributions are fully compatible with data upstream of the Sicily Strait and in the Western Mediterranean. The tracer data show that mixing reached to the bottom and confirm a cyclonic nature of the deep water circulation in the Tyrrhenian. They furthermore indicate that horizontal homogenization of the deep waters occurs on a time scale of several years. Various features point to a reduced impact of Western Mediterranean Deep Water (WMDW) in the Tyrrhenian during the enhanced-convection period. This is an important finding because it implies less upward mixing of WMDW, which has been named a major process to enable the WMDW to leave the Mediterranean via the Gibraltar Strait. On the other hand, the TDW outflow for several years represented a major influx of enhanced salinity and density waters into the deep-water range of the Western Mediterranean.

scholarly journals A Multivariate Study of T/V Forms in European Languages Based on a Parallel Corpus of Film Subtitles

2017 ◽  
Vol 15 (2) ◽  
pp. 153-172 ◽  
Author(s):  
Natalia Levshina
Keyword(s):  
Multivariate Analyses ◽  
The Other ◽  
Conditional Inference ◽  
Contextual Variables ◽  
Linguistic Differences ◽  
Parallel Corpus ◽  
Contextual Features ◽  
European Languages ◽  
Multivariate Study ◽  
Conditional Inference Trees

The present study investigates the cross-linguistic differences in the use of so-called T/V forms (e.g. French tu and vous, German du and Sie, Russian ty and vy) in ten European languages from different language families and genera. These constraints represent an elusive object of investigation because they depend on a large number of subtle contextual features and social distinctions, which should be cross-linguistically matched. Film subtitles in different languages offer a convenient solution because the situations of communication between film characters can serve as comparative concepts. I selected more than two hundred contexts that contain the pronouns you and yourself in the original English versions, which are then coded for fifteen contextual variables that describe the Speaker and the Hearer, their relationships and different situational properties. The creators of subtitles in the other languages have to choose between T and V when translating from English, where the T/V distinction is not expressed grammatically. On the basis of these situations translated in ten languages, I perform multivariate analyses using the method of conditional inference trees in order to identify the most relevant contextual variables that constrain the T/V variation in each language.

scholarly journals Metagenomic Characterization Reveals Pronounced Seasonality in the Diversity and Structure of the Phyllosphere Bacterial Community in a Mediterranean Ecosystem

2019 ◽  
Vol 7 (11) ◽  
pp. 518 ◽  
Author(s):  
Despoina Vokou ◽  
Savvas Genitsaris ◽  
Katerina Karamanoli ◽  
Katerina Vareli ◽  
Marina Zachari ◽  
...  
Keyword(s):  
Bacterial Community ◽  
High Throughput Sequencing ◽  
Bacterial Colonization ◽  
The Other ◽  
Mediterranean Ecosystem ◽  
Seasonal Differences ◽  
Operational Taxonomic Units ◽  
Seasonal Environment ◽  
Habitat Specialists ◽  
Taxonomic Groups

We explore how the phyllosphere microbial community responds to a very seasonal environment such as the Mediterranean. For this, we studied the epiphytic bacterial community of a Mediterranean ecosystem in summer and winter, expecting to detect seasonal differences at their maximum. With high-throughput sequencing (HTS), we detected the operational taxonomic units (OTUs) present in the phyllosphere and also in the surrounding air. The epiphytic community is approximately five orders of magnitude denser than the airborne one and is made almost exclusively by habitat specialists. The two communities differ considerably but Proteobacteria and Actinobacteria are dominant in both. Of the five most abundant phyllosphere OTUs, two were closely related to Sphingomonas strains, one to Methylobacterium and the other two to Rhizobiales and Burkholderiales. We found the epiphytic community to become much richer, more distinct, even and diverse, denser and more connected in summer. In contrast, there was no difference in the level of bacterial colonization of the phyllosphere between the two seasons, although there were seasonal differences for individual taxonomic groups: Firmicutes, Gemmatimonadetes and Chlroroflexi had a higher participation in summer, whereas the major Proteobacteria classes presented reverse patterns, with Betaproteobacteria increasing in summer at the expense of the prominent Alphaproteobacteria.

scholarly journals Directionally Correlated Movement Can Drive Qualitative Changes in Emergent Population Distribution Patterns

Mathematics ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 640
Author(s):  
Jonathan R. Potts
Keyword(s):  
Spatial Distribution ◽  
Pattern Formation ◽  
Characteristic Time ◽  
Population Distribution ◽  
Distribution Patterns ◽  
The Other ◽  
Linear Pattern ◽  
Fundamental Goal ◽  
Spatial Pattern Formation ◽  
Qualitative Changes

A fundamental goal of ecology is to understand the spatial distribution of species. For moving animals, their location is crucially dependent on the movement mechanisms they employ to navigate the landscape. Animals across many taxa are known to exhibit directional correlation in their movement. This work explores the effect of such directional correlation on spatial pattern formation in a model of between-population taxis (i.e., movement of each population in response to the presence of the others). A telegrapher-taxis formalism is used, which generalises a previously studied diffusion-taxis system by incorporating a parameter T, measuring the characteristic time for directional persistence. The results give general criteria for determining when changes in T will drive qualitative changes in the predictions of linear pattern formation analysis for N ≥ 2 populations. As a specific example, the N = 2 case is explored in detail, showing that directional correlation can cause one population to ‘chase’ the other across the landscape while maintaining a non-constant spatial distribution. Overall, this study demonstrates the importance of accounting for directional correlation in movement for understanding both quantitative and qualitative aspects of species distributions.

The elevation gradient of lichen species richness in Nepal

2009 ◽  
Vol 42 (1) ◽  
pp. 83-96 ◽  
Author(s):  
Chitra Bahadur BANIYA ◽  
Torstein SOLHØY ◽  
Yngvar GAUSLAA ◽  
Michael W. PALMER
Keyword(s):  
Species Richness ◽  
Endemic Species ◽  
Elevation Gradient ◽  
Distribution Patterns ◽  
Lichen Species ◽  
Ecological Niches ◽  
Published Data ◽  
Elevation Gradients ◽  
Wide Range ◽  
Taxonomic Groups

AbstractThis study of elevation gradients of lichen species richness in Nepal aimed to compare distribution patterns of different life-forms, substratum affinities, photobiont types, and Nepalese endemism. Distribution patterns of lichens were compared with elevational patterns shown by a wide range of taxonomic groups of plants along the Nepalese Himalayan elevational gradient between 200–7400m. We used published data on the elevation records of 525 Nepalese lichen species to interpolate presence between the maximum and minimum recorded elevations, thereby giving estimates of lichen species richness at each 100-m elevational band. The observed patterns were compared with previously published patterns for other taxonomic groups. The total number of lichens as well as the number of endemic species (55 spp.) showed humped relationships with elevation. Their highest richness was observed between 3100–3400 and 4000–4100m, respectively. Almost 33% of the total lichens and 53% of the endemic species occurred above the treeline (>4300m). Non-endemic richness had the same response as the total richness. All growth forms showed a unimodal relationship of richness with elevation, with crustose lichens having a peak at higher elevations (4100–4200m) than fruticose and foliose lichens. Algal and cyanobacterial lichen richness, as well as corticolous lichen richness, all exhibited unimodal patterns, whereas saxicolous and terricolous lichen richness exhibited slightly bimodal relationships with elevation. The highest lichen richness at mid altitudes concurred with the highest diversity of ecological niches in terms of spatial heterogeneity in rainfall, temperature, cloud formation, as well as high phorophyte abundance and diversity implying large variation in bark roughness, moisture retention capacity, and pH. The slightly bimodal distributions of saxicolous and terricolous lichens were depressed at the elevational maximum of corticolous lichens.

scholarly journals Marine Cyanophages Demonstrate Biogeographic Patterns throughout the Global Ocean

2014 ◽  
Vol 81 (1) ◽  
pp. 441-452 ◽  
Author(s):  
Sijun Huang ◽  
Si Zhang ◽  
Nianzhi Jiao ◽  
Feng Chen
Keyword(s):  
Strong Correlation ◽  
Multivariate Analyses ◽  
Distribution Patterns ◽  
Mantel Test ◽  
Global Ocean ◽  
Broad Host Range ◽  
Content Type ◽  
Biogeographic Patterns ◽  
Phylogenetic Lineages ◽  
Distinct Distribution

ABSTRACTMyoviruses and podoviruses that infect cyanobacteria are the two major groups of marine cyanophages, but little is known of how their phylogenetic lineages are distributed in different habitats. In this study, we analyzed the phylogenetic relationships of cyanopodoviruses and cyanomyoviruses based on the existing genomes. The 28 cyanomyoviruses were classified into four clusters (I to IV), and 19 of the 20 cyanopodoviruses were classified into two clusters, MPP-A and MPP-B, with four subclusters within cluster MPP-B. These genomes were used to recruit cyanophage-like fragments from microbial and viral metagenomes to estimate the relative abundances of these cyanophage lineages. Our results showed that cyanopodoviruses and cyanomyoviruses are both abundant in various marine environments and that clusters MPP-B, II and III appear to be the most dominant lineages. Cyanopodoviruses and cluster I and IV cyanomyoviruses exhibited habitat-related variability in their relative levels of abundance, while cluster II and III cyanomyoviruses appeared to be consistently dominant in various habitats. Multivariate analyses showed that reads that mapped toSynechococcusphages andProchlorococcusphages had distinct distribution patterns that were significantly correlated to those ofSynechococcusandProchlorococcus, respectively. The Mantel test also revealed a strong correlation between the community compositions of cyanophages and picocyanobacteria. Given that cyanomyoviruses tend to have a broad host range and some can cross-infectSynechococcusandProchlorococcus, while cyanopodoviruses are commonly host specific, the observation that their community compositions both correlated significantly with that of picocyanobacteria was unexpected. Although cyanomyoviruses and cyanopodoviruses differ in host specificity, their biogeographic distributions are likely both constrained by the picocyanobacterial community.

Sign in / Sign up

Export Citation Format

Share Document