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The use of taxonomic distinctness indices in assessing patterns of biodiversity in modular organisms 总被引：1，自引：0，他引：1
Stanislao Bevilacqua Simonetta Fraschetti Antonio Terlizzi & Ferdinando Boero 《Marine Ecology》2009,30(2):151-163
Estimating diversity of modular organisms may be problematic due to actual difficulties in discriminating between 'individuals' and quantifying their abundances. Quantitative data, when available, are collected through methods that could preclude the application of classical diversity indices, making comparisons among studies difficult. Taxonomic distinctness indices, such as the 'Average Taxonomic Distinctness' (Δ+ ) and the 'Variation in Taxonomic Distinctness' (Λ+ ) may represent suitable tools in investigating diversity beyond the simple species number. The potential usefulness of such indices has been explored almost exclusively on unitary organisms, neglecting modular ones. In this study, we employed Δ+ and Λ+ to analyse patterns of diversity of epiphytic hydroid assemblages living on Cystoseira seaweeds at a hierarchy of spatial scales, along 800 km of rocky coast (SE Italy). ANOVA on species richness and Λ+ showed no significant difference in sample diversity at the investigated spatial scales. In contrast, there were significant differences at the scale of 10s of km in Δ+ . Analyses based on simulations detected significant variations at all spatial scales in Δ+ . Such findings underline the potential of Δ+ in highlighting relevant spatial scales of variation in patterns of hydroid diversity. Our results also suggest that the interplay between natural environmental variations and the complex ecological traits of modular organisms might affect taxonomic distinctness indices. We stress the need for further investigations focusing on modular organisms before any generalizations on the use of taxonomic relatedness measures in examining marine biodiversity can be made. 相似文献
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Cristiana Guerranti Stefania Ancora Nicola Bianchi Guido Perra Emiliano Leonida Fanello Simonetta Corsolini Maria Cristina Fossi Silvano Ettore Focardi 《Marine pollution bulletin》2013
Perfluorinated compounds (PFCs), widely used for their hydro-oil repellent properties, are almost non-degradable in the environment; there is scientific evidence that indicate bioaccumulation. They represent a threat to many organisms, because they are toxic and are endocrine disruptors. Scientific studies have demonstrated the presence of PFCs in blood and liver samples of fish, turtles, birds and mammals of marine ecosystems in different geographical areas. The aim of this study was to determine the distribution of PFOS and PFOA in blood samples of the marine turtle Caretta caretta, using a minimally invasive sampling procedure. 49 blood samples of marine turtle, taken from several Italian marine turtle rescue centers, were analyzed. While PFOA was never detected, measurable concentrations of PFOS were found in 15 blood samples; the values show a range from 1.14 ng/g to 28.51 ng/g (wet wt.). No differences between groups of samples taken from different areas were found. 相似文献
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The study of a 275.5 m thick section of white, pelagic limestones occupying the valley of the Fonte del Giordano river on the southern slope of Mt. Montagnola has yielded a biostratigraphically controlled clear magnetic reversal pattern after thermal cleaning. The magnetic stratigraphy of the lower 131 m of the section (Calpionellid zones) is correlatable with the M-sequence of oceanic magnetic anomalies between M-19 and M-14. The reversal stratigraphy of the upper 81.5 m of the section (Radiolaria zone) has also been tied to the oceanic polarity time scale by making linear interpolation for a missing 63 m thickness underneath it.Besides the Fonte del Giordano section two Berriasian outcrops each with a different bedding attitude were studied at Gubbio and near Cagli for tectonic tilt test giving positive results. The mean palaeomagnetic pole position for the Late Jurassic/Early Cretaceous after bedding correction is: Φ = 19.1°, Λ = 288.2°, k = 148.7, α95 = 10.2° (N = 3), confirming the presence of a large swing in the polar path, a common behaviour of apparent polar wandering for the peri-Adriatic region during this time. 相似文献
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Fraschetti S Terlizzi A Bussotti S Guarnieri G D'Ambrosio P Boero F 《Marine environmental research》2005,59(4):309-332
Marine protected areas (MPAs) are aimed at managing and protecting marine environments. Their design, however, often disregards both a thorough knowledge of the distribution of habitats and assemblages and the use of proper experimental evaluations of the efficacy of MPAs by comparing protected vs. unprotected zones. About 200 MPAs have been recently instituted in the Mediterranean area, but the evidence of their efficacy is scant. The MPA of Torre Guaceto (Southern Adriatic Sea, Italy) is one of the rare cases of effective protection enforcement. The reserve was instituted more than 10 years ago, a period currently considered as sufficient to show responses by organisms to protection. The MPA is divided into a C zone, the general reserve, where many activities are permitted, a B zone, the partial reserve where restrictions increase and two A zones, the integral reserve where access is prohibited. The goals of the paper were to map the distribution of benthic assemblages to assess if they were properly represented in the differently protected zones, and to test the efficacy of protection by quantifying possible differences between the assemblages in two control areas and in the two A zones, where human impact is completely excluded. The analysis of habitat and assemblage distribution within the MPA showed that the zones with total protection do not include most valuable environmental types. Most of the considered variables (i.e. cover of substratum, number of taxa, and average abundance of the most common taxa) were not significantly different in and out of the A zones, at each time of sampling. Results, however, suggested a possible effect of protection in modifying patterns of abundance of sponges under Cystoseira canopy (more abundant in the fully protected zone). In the subtidal habitat, differences were found in the structure of the whole assemblage and in the abundance of encrusting coralline red algae (more abundant outside the fully protected area). Notwithstanding the correct general methodology employed in the study, a lack of statistical power could have a role in preventing the detection of ecologically relevant effects of protection. In some instances, data pooling allowed a discrimination between cases where there was clearly no effect of protection and cases where there might be. On this basis, the optimization of this experimental design should be considered in further studies. In any case, if the goals of MPAs have not been clearly stated, efficacy of protection might prove very difficult to test even with the use of sound experimental designs. 相似文献
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Simonetta Rubol Daniele Tonina Lionel Vincent Jill A. Sohm William Basham Ralph Budwig Pratixa Savalia Eva Kanso Douglas G. Capone Kenneth H. Nealson 《水文研究》2018,32(3):402-407
We describe a novel inexpensive method, utilizing particle image velocimetry (PIV) and refractive index‐matching (RIM) for visualizing and quantifying the flow field within bio‐amended porous media. To date, this technique has been limited to idealized particles, whose refractive index does not match that of fresh water and thus requires specialized and often toxic or hazardous fluids. Here, we use irregularly shaped grains made of hydrogel as the solid matrix and water as the fluid. The advantage of using water is that it provides, for the first time, the opportunity to study both hydraulic and biological processes, which typically occur in soils and streambeds. By using RIM coupled with PIV (RIM‐PIV), we measured the interstitial flow field within a cell packed with granular material consisting of hydrogel grains in a size range of 1–8 mm, both in the presence and in the absence of Sinorhizobium meliloti bacteria (strain Rm8530). We also performed experiments with fluorescent tracer (fluorescein) and fluorescent microbes (Shewanella GPF MR‐1) to test the capability of visualizing solute transport and microbial movements. Results showed that the RIM‐PIV can measure the flow field for both biofilm‐free and biofilm‐covered hydrogel grains. The fluorescent tracer injection showed the ability to visualize both physical (concave surfaces and eddies) and biological (biofilms) transient storage zones, whereas the fluorescent microbe treatment showed the ability to track microbial movements within fluids. We conclude that the proposed methodology is a promising tool to visualize and quantify biofilm attachment, growth, and detachment in a system closer to natural conditions than a 2D flow cell experiment. 相似文献