Search results for " Ecosystem"

2019

Here we explore the carbon and oxygen isotope compositions of the co-existing carbonate and phosphate fractions of fish tooth enameloid as a tool to reconstruct past aquatic fish environments and harvesting grounds. The enameloid oxygen isotope compositions of the phosphate fraction (δ18OPO4) vary by as much as ~4‰ for migratory marine fish such as gilthead seabream (Sparus aurata), predominantly reflecting the different saline habitats it occupies during its life cycle. The offset in enameloid Δ18OCO3-PO4 values of modern marine Sparidae and freshwater Cyprinidae from the Southeast Mediterranean region vary between 8.1 and 11.0‰, similar to values reported for modern sharks. The mean δ13C …

The Microbiota: A Microbial Ecosystem Built on Mutualism Prevails

2019

Phytophthora Diversity in a Sentinel Arboretum and in a Nature Reserve Area

2020

Most soilborne Phytophthora species are invasive plant pathogens and nursery plants for transplanting are considered a primary pathway for the introduction of exotic Phytophthora species into plant diversity conservation areas and sites. As a preliminary step toward investigating this subject, we compared the diversity of Phytophthora in the protected natural area Complesso Speleologico Villasmundo S. Alfio Nature Reserve (NR) (Melilli, Siracusa) and the botanical garden (BG) of the University of Catania (Catania), in eastern Sicily (southern Italy). Sampling was carried out during the spring of 2019. Overall 29 rhizosphere soil samples were collected, 17 from different types of vegetation …

Genetic and Environmental Controls on Nitrous Oxide Accumulation in Lakes

2015

We studied potential links between environmental factors, nitrous oxide (N2O) accumulation, and genetic indicators of nitrite and N2O reducing bacteria in 12 boreal lakes. Denitrifying bacteria were investigated by quantifying genes encoding nitrite and N2O reductases (nirS/nirK and nosZ, respectively, including the two phylogenetically distinct clades nosZ(I) and nosZ(II)) in lake sediments. Summertime N2O accumulation and hypolimnetic nitrate concentrations were positively correlated both at the inter-lake scale and within a depth transect of an individual lake (Lake Vanajavesi). The variability in the individual nirS, nirK, nosZ(I), and nosZ(II) gene abundances was high (up to tenfold) a…

The spread of the Atlantic blue crab Callinectes sapidus Rathbun 1896 in the Mediterranean Sea: analysis of environmental and trophic niche and metal…

2023

Biological invasions are globally acknowledged as one of the major causes of biodiversity loss. Considering the urgency of understanding what are the effects of biological invasions on recipient ecosystems, this research focuses on the Atlantic blue crab Callinectes sapidus, one of the most successful invaders of Mediterranean coastal ecosystems. First, a general assessment of the overlap of the Grinnellian niche of the species in native and invaded ranges was carried out to verify whether the blue crab maintained the characteristics of its climatic niche when establishing in invaded areas (niche conservatism hypothesis) or, alternatively, it adapted to the specific abiotic characteristics …

Stochastic 0-dimensional Biogeochemical Flux Model: Effect of temperature fluctuations on the dynamics of the biogeochemical properties in a marine e…

2021

Abstract We present a new stochastic model, based on a 0-dimensional version of the well known biogeochemical flux model (BFM), which allows to take into account the temperature random fluctuations present in natural systems and therefore to describe more realistically the dynamics of real marine ecosystems. The study presents a detailed analysis of the effects of randomly varying temperature on the lower trophic levels of the food web and ocean biogeochemical processes. More in detail, the temperature is described as a stochastic process driven by an additive self-correlated Gaussian noise. Varying both correlation time and intensity of the noise source, the predominance of different plank…

A novel method to simulate the 3D chlorophyll distribution in marine oligotrophic waters

2021

Abstract A 3D advection-diffusion-reaction model is proposed to investigate the abundance of phytoplankton in a difficult-to-access ecosystem such as the Gulf of Sirte (southern Mediterranean Sea) characterized by oligotrophic waters. The model exploits experimentally measured environmental variables to reproduce the dynamics of four populations that dominate phytoplankton community in the studied area: Synechococcus, Prochlorococcus HL, Prochlorococcus LL and picoeukaryotes. The theoretical results obtained for phytoplankton abundances are converted into chl-a and Dvchl-a concentrations, and the simulated vertical chlorophyll profiles are compared to the corresponding experimentally acquir…

Within-lake variability in carbon and nitrogen stable isotope signatures

2006

SUMMARY 1. We assessed spatial and temporal variation in carbon and nitrogen isotopic signatures in different compartments of a single lake ecosystem. Stable isotope analyses were made on samples of particulate organic matter (POM), zooplankton, periphyton, macrophytes, macroinvertebrates and fish collected from several locations throughout the ice-free period. 2. No spatial variation in d 13 Co rd 15 N values was found for pelagic samples of POM and zooplankton. However, pelagic d 15 N signatures increased steadily through the summer resulting in an almost 6& average increase in POM and zooplankton. A concurrent decrease in epilimnetic nitrate concentrations suggested that the increase in …

Corrigendum to “Climate variability and lake ecosystem responses in western Scandinavia (Norway) during the last Millennium” [Palaeogeogr. Palaeoclim…

2020

Diversification and performance in the mobile app market: The role of the platform ecosystem

2019

Abstract We examine the effect of app developers' product line diversification decision on their performance and shed light on whether the type of platform ecosystem (open versus closed) where they commercialize apps influences this effect. We compare the revenue performance of diversified and specialized developers in Apple's App Store and Google Play. We show that in the Apple's App Store (closed platform) diversified developers always display lower performance than their specialized counterparts. In Google Play (open platform) diversification is beneficial in categories where diversified developers have predominant market share, whereas it is detrimental in categories dominated by specia…