Search results for " Ecosystem"

Habitat preferences of bats in a rural area of Sicily determined by acoustic surveys

2009

<strong>Abstract</strong> The bat fauna of a 60 km<sup>2</sup> wide area representing the typical rural landscape of inland Sicily and including the small “Rocche di Entella” karstic plateau (Natural Reserve and SAC) was surveyed between May 2006 and September 2007. Sampling was carried out at 95 sites, distributed proportionally in six main habitats. Bat calls were time-expanded with a D980 bat detector and then identified to species level by a Discriminant Function Analysis. We recorded 305 bat passes and identified 96.4% of recorded calls. Moon phase, cloud cover and their interaction did not affect total bat activity, nor did the sampling peri…

How diffusivity, thermocline and incident light intensity modulate the dynamics of Deep Chlorophyll Maximum in Tyrrhenian Sea

2015

During the last few years theoretical works have shed new light and proposed new hypotheses on the mechanisms which regulate the spatio-temporal behaviour of phytoplankton communities in marine pelagic ecosystems. Despite this, relevant physical and biological issues, such as effects of the time- dependent mixing in the upper layer, competition between groups, and dynamics of non-stationary deep chlorophyll maxima, are still open questions. In this work, we analyze the spatio-temporal behaviour of five phytoplankton populations in a real marine ecosystem by using a one-dimensional reaction-diffusion-taxis model. The study is performed, taking into account the seasonal variations of environm…

Spatio-temporal dynamics of a planktonic system and chlorophyll distribution in a 2D spatial domain: matching model and data

2017

AbstractField data on chlorophyll distribution are investigated in a two-dimensional spatial domain of the Mediterranean Sea by using for phytoplankton abundances an advection-diffusion-reaction model, which includes real values for physical and biological variables. The study exploits indeed hydrological and nutrients data acquired in situ, and includes intraspecific competition for limiting factors, i.e. light intensity and phosphate concentration. As a result, the model allows to analyze how both the velocity field of marine currents and the two components of turbulent diffusivity affect the spatial distributions of phytoplankton abundances in the Modified Atlantic Water, the upper layer…

Reply to Magnani et al.: Linking large-scale chlorophyll fluorescence observations with cropland gross primary production

2014

Guanter, Luis et al.

Dynamics of Two Picophytoplankton Groups in Mediterranean Sea: Analysis of the Deep Chlorophyll Maximum by a Stochastic Advection-Reaction-Diffusion …

2013

A stochastic advection-reaction-diffusion model with terms of multiplicative white Gaussian noise, valid for weakly mixed waters, is studied to obtain the vertical stationary spatial distributions of two groups of picophytoplankton, i.e., picoeukaryotes and Prochlorococcus, which account about for 60% of total chlorophyll on average in Mediterranean Sea. By numerically solving the equations of the model, we analyze the one-dimensional spatio-temporal dynamics of the total picophytoplankton biomass and nutrient concentration along the water column at different depths. In particular, we integrate the equations over a time interval long enough, obtaining the steady spatial distributions for th…

Effects of elevated production of autochthonous dissolved organic matter on the freely dissolved concentration of cadmium

2018

Eutrophication enhances the production of autochthonous dissolved organic matter (DOM), which is a major driving factor behind the impairment of many aquatic ecosystems. In a mesocosm study, we investigated the effects of the abundance and composition of DOM on the potential bioavailability of cadmium (Cd) caused by eutrophication, using three-dimensional excitation-emission matrix fluorescence spectroscopy integrated with tangential flow ultrafiltration technology. The complexing capacity of DOM-Cd and the sorption distribution coefficient between DOM and the bulk solution was calculated based on a 1 : 1 complexation model. The fluorescent DOM was decomposed into three components (one prot…

Statistical characterisation of heavy metal contents inParacentrotus lividusfrom Mediterranean Sea

2014

This work focuses on the estimation of Hg, As, Cr, Ni, Cu, V, Cd and Pb by inductively coupled plasma mass spectrometry in 135 adult specimens of Paracentrotus lividus collected in different coastal areas of Sicily (Gela, Punta Secca, Ragusa (RG), Siracusa, Priolo, Catania, Messina, Milazzo, Brolo and Filicudi), in order to monitor the Mediterranean marine ecosystem by use of sea urchin as bioindicator. Moreover, the paper deals with the statistical classification of the tested samples according to the sampling area based on metal concentrations. The descriptive statistics findings were obtained and, a starting multivariate matrix was built. Data-sets were subjected to Kruskal-Wallis test t…

Patterns of soil microbial biomass and diversity across Mediterranean agroecosystems in areas under desertification risk

2022

<p><strong>SEM study of species of <em>Oswaldella</em> Stechow, 1919 (Cnidaria, Hydrozoa, </strong><br /><stro…

2015

Oswaldella is the most speciose genus, and one of the most characteristic, of hydrozoans inhabiting the Antarctic benthic marine ecosystem. Its species have relatively many important taxonomic characters allowing for their identification. Some of them, however, are difficult to study properly with a compound microscope. With the aim of improving scientific knowledge concerning species of the genus, a SEM survey of species of Oswaldella was carried out to study key morphological characters. Fourteen out of the 27 known nominal species were considered. The study has revealed unknown important characters, such as the presence of nematothecae associated with the nematophores at the cauline apop…

Contrasting behavioural responses of two egg parasitoids to buckwheat floral scent is reflected in field parasitism rates

2017

The use of food supplements in conservation biological control (CBC) programmes is considered an essential element for increasing parasitoid fitness and their population density leading to an increase in overall parasitism levels. However, non-crop habitats that substitute the necessary resources for natural enemies have not always achieved the desired effects. It is suggested that the composition of flower strips in agricultural systems around/in agricultural fields plays an important role because not all plant species are equally suitable and the consumption of food resources by parasitoids can shape direct and indirect interactions with other arthropods and the community complex. We deve…