Search results for "marine ecosystem"
showing 10 items of 103 documents
Global distributions of diazotrophs Gamma-A nifH genes abundance - Depth integrated values computed from a collection of source datasets - Contributi…
2013
The MAREDAT atlas covers 11 types of plankton, ranging in size from bacteria to jellyfish. Together, these plankton groups determine the health and productivity of the global ocean and play a vital role in the global carbon cycle. Working within a uniform and consistent spatial and depth grid (map) of the global ocean, the researchers compiled thousands and tens of thousands of data points to identify regions of plankton abundance and scarcity as well as areas of data abundance and scarcity. At many of the grid points, the MAREDAT team accomplished the difficult conversion from abundance (numbers of organisms) to biomass (carbon mass of organisms). The MAREDAT atlas provides an unprecedente…
Sunscreen Products as Emerging Pollutants to Coastal Waters
2013
A growing awareness of the risks associated with skin exposure to ultraviolet (UV) radiation over the past decades has led to increased use of sunscreen cosmetic products leading the introduction of new chemical compounds in the marine environment. Although coastal tourism and recreation are the largest and most rapidly growing activities in the world, the evaluation of sunscreen as source of chemicals to the coastal marine system has not been addressed. Concentrations of chemical UV filters included in the formulation of sunscreens, such as benzophehone 3 (BZ-3), 4-methylbenzylidene camphor (4-MBC), TiO2 and ZnO, are detected in nearshore waters with variable concentrations along the day a…
Sea Surface Temperature Effects on the Mediterranean Marine Ecosystem: a Semiparametric Model Approach
2021
Ocean warming is a worldwide phenomenon. The mean temperature of the catch (MTC) is becoming one of the leading indicators to assess the impact of sea surface temperature on fish communities. In this study, we apply a semiparametric regression approach to the MTC of the catches from MEDITS bottom trawl program in the Strait of Sicily (Central Mediterranean Sea) for the period 1995 to 2018 to evaluate the effects of climate change on continental shelf fish community. All covariates included in the model have a significant impact on the MTC level. Notably, the sea surface temperature (SST) effect on the MTC depends on depth, being positive near the surface and negative at the bottom.
Spatio-temporal behaviour of five picophytoplankton populations in Tyrrhe- nian Sea: Model and data
2014
Recent works presented detailed analyses of spatio-temporal dynamics in marine ecosystems, reproducing real vertical distributions of phytoplankton biomass. These study however do not take into account the changes in environmental variables. On the contrary, seasonal variations can influence considerably the primary production, i.e. phytoplankton biomass, in marine ecosystems, determining significative consequences in the whole food chain, in particular fish species, whose growth is mainly explained by seasonal changes in the chlorophyll concentration, a marker of phytoplankton species. Here we present a one-dimensional reaction-diffusion-taxis model to describe the spatio-temporal dynamics…
Reaction-diffusion-taxis model for spatio-temporal dynamics of five picophytoplankton populations
2014
Recently new models were devised to study spatio-temporal dynamics of phytoplankton populations in view of obtaining more precise predictions of the vertical biomass distributions in marine ecosystems. These studies can be crucial from the point of view of shery. Indeed the abundance of fi sh species is strictly connected with primary production, i.e. phytoplankton biomass, responsible for chlorophyll concentration. In this work a one-dimensional deterministic reaction-di ffusion-taxis model is used to reproduce the spatio-temporal dynamics, along a water column, of five picophytoplankton populations sampled in a real ecosystem. In our analysis, to better reproduce the spatio-temporal behav…
The invasive seaweed Asparagopsis taxiformis erodes the habitat structure and biodiversity of native algal forests in the Mediterranean Sea
2021
Abstract Invasive seaweeds are listed among the most relevant threats to marine ecosystems worldwide. Biodiversity hotspots, such as the Mediterranean Sea, are facing multiple invasions and are expected to be severely affected by the introduction of new non-native seaweeds in the near future. In this study, we evaluated the consequences of the shift from the native Ericaria brachycarpa to the invasive Asparagopsis taxiformis habitat on the shallow rocky shores of Favignana Island (Egadi Islands, MPA, Sicily, Italy). We compared algal biomass and species composition and structure of the associated epifaunal assemblages in homogenous and mixed stands of E. brachycarpa and A. taxiformis. The r…
A geo-statistical predictive approach to the Habitat mapping of Vulnerable Marine Ecosystems along the northern Sicily inner continental shelf (south…
2016
The main aim of this work is to statistically predict the distribution of Vulnerable Marine Ecosystems (VMEs) along the continental shelf regions of the northern Sicilian margin (southern Mediterranean). The considered habitats, already mapped in the area on a qualitative base, are the Posidonia oceanica and Cymodocea nodosa seagrasses and the Coralligenous biocenosis. Posidonia oceanica and Coralligenous are considered as VMEs owing to their value as environmental indicators and biodiversity hotspots in coastal marine areas. For this reason, several actions were aimed in recent years to their complete characterization and mapping. The study area is located in the continental shelf of the n…
Climate driven life histories: the case of the Mediterranean Storm petrel
2014
Seabirds are affected by changes in the marine ecosystem. The influence of climatic factors on marine food webs can be reflected in long-term seabird population changes. We modelled the survival and recruitment of the Mediterranean storm petrel (Hydrobates pelagicus melitensis) using a 21-year mark-recapture dataset involving almost 5000 birds. We demonstrated a strong influence of prebreeding climatic conditions on recruitment age and of rainfall and breeding period conditions on juvenile survival. The results suggest that the juvenile survival rate of the Mediterranean subspecies may not be negatively affected by the predicted features of climate change, i.e., warmer summers and lower rai…
Saving the pharmacy of the sea: How does global change affect species with bioactive potential in the Mediterranean?
2020
Several marine species in the Mediterranean produce molecules with bioactive potential that could be used to develop new drugs (antibiotics, antifungals, antivirals, and antitumourals). Different human activities such as pollution, marine recreation, and fishing, as well as climate change, threaten and even endanger some of these species. These vulnerable species with bioactive potential must be protected, especially in marine reserves, not only because they are valuable components of marine ecosystems, but also because they are a potential source of molecules with pharmacological properties that are currently being researched for the creation of new drugs.
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…