Entity

Time filter

Source Type


Denaro G.,University of Palermo | Valenti D.,University of Palermo | La Cognata A.,University of Palermo | Spagnolo B.,University of Palermo | And 6 more authors.
Ecological Complexity | Year: 2013

In this paper, by using a stochastic reaction-diffusion-taxis model, we analyze the picophytoplankton dynamics in the basin of the Mediterranean Sea, characterized by poorly mixed waters. The model includes intraspecific competition of picophytoplankton for light and nutrients. The multiplicative noise sources present in the model account for random fluctuations of environmental variables. Phytoplankton distributions obtained from the model show a good agreement with experimental data sampled in two different sites of the Sicily Channel. The results could be extended to analyze data collected in different sites of the Mediterranean Sea and to devise predictive models for phytoplankton dynamics in oligotrophic waters. © 2012 Elsevier B.V.


Fadhlaoui-Zid K.,National Institute of Marine science and Technologies | Knittweis L.,Capture Fisheries Section | Aurelle D.,Aix - Marseille University | Nafkha C.,National Institute of Marine science and Technologies | And 6 more authors.
Comptes Rendus - Biologies | Year: 2012

The polymorphism of the mitochondrial gene cytochrome oxidase III was studied in the Mediterranean octopus, Octopus vulgaris Cuvier, 1797. A total of 202 specimens from seven sampling sites were analysed with the aim of elucidating patterns of genetic structure in the central Mediterranean Sea and to give an insight into the phylogeny of the Octopus genus. Phylogenetic analyses showed that individuals from the central Mediterranean belong to the O. vulgaris species whose limits should nevertheless be clarified. Concerning genetic structure, two high-frequency haplotypes were present in all locations. The overall genetic divergence (ΦST = 0.05, P < 0.05) indicated a significant genetic structuring in the study area and an AMOVA highlighted a significant break between western and eastern Mediterranean basins (ΦCT = 0.094, P < 0.05). Possible explanations for the observed patterns of genetic structuring are discussed with reference to their relevance for fisheries management. © 2012 Académie des sciences.


Elhajaji A.,Liverpool John Moores University | Al Khaddar R.,Liverpool John Moores University | Haddoud D.,Marine Biology Research Center | Durr S.,Liverpool John Moores University
World Environmental and Water Resources Congress 2015: Floods, Droughts, and Ecosystems - Proceedings of the 2015 World Environmental and Water Resources Congress | Year: 2015

Seawater desalination has become a rapidly growing industry in Mediterranean countries due to the water scarcity. This activity results in environmental problems chiefly generated by brine discharged into the sea, which alters the physico-chemical parameters of the receiving water and threatens its marine biota. This paper has examined data from the field study survey carried out in Libya to investigate the changes in physico-chemical parameters of the receiving water due to brine emitted from the Zwuarah Desalination Plant. 19 seawater samples near the outfall of ZWDP were collected and analysed. The results of the data collection are characterized by principal-component analysis (PCA) and it is indicated that the pattern is best explained in PC1, PC2, PC3, PC4 and PC5 with 67.6%, 81.4%, 88.2%, 92.4% and 94.9% of the total variance respectively. Wide variations in the physico-chemical parameters of the receiving seawater near the ZWDP outfall have been observed between total hardness, calcium and magnesium hardness, sulfate, potassium, sodium, chloride, phosphate, iron and nitrate ions, sea bed and the sea surface temperature, pH, dissolved oxygen levels and Salinity. These were scattered in ranges (-500 to + 9,071 mgl-1), (-800 to + 361 mgl-1), (+ 5300 to + 1370 mgl-1), (-306 to-216 mgl-1), (+ 37 to + 1,900 mgl-1), (-1,400 to + 1,183 mgl-1), (-408 to-570 mgl-1), (+ 945 to + 6,550 mgl-1), (-1,626 to + 2,625 mgl-1), (+ 0.089 mgl-1), (+ 0.6966 mgl-1), (+ 0.15 mgl-1), (+15.4°C to + 3°C), (-0.14 to + 0.06) (-4.67 to-2.1 mgl-1) and (+9.2 psu) respectively. The results revealed that physico-chemical parameters at the study site were different in ambient seawater and that indicated there is a threat to the marine ecosystem. © 2015 ASCE.


Elhajaji A.,Liverpool John Moores University | Al Khaddar R.,Liverpool John Moores University | Durr S.,Liverpool John Moores University | Haddoud D.,Marine Biology Research Center
World Environmental and Water Resources Congress 2014: Water Without Borders - Proceedings of the 2014 World Environmental and Water Resources Congress | Year: 2014

In Libya, as water resources are rapidly being exhausted due to an increase in both population growth and water consumption in various sectors, the Libyan government has turned to integrating nonconventional water resources such as multieffect distillation (MED and MED with TVC) to compensate for the water deficit. This paper has determined that the cost of desalinated water by thermal desalination plants is about $0.47/m3, thus seeing this as the best option for providing water resources, due to unlimited seawater sources, compared with the cost per cubic meter produced by the Great Man-Made River Project, which is estimated to cost 0.83$/m3. Moreover, the results indicate that the highest annual water deficit in Libyan water regions was in Jabal Nafusah and Jifarah plain, Middle Zone, and Aljabal Alakhdar Region in the north and middle of the country equaling 1,450 million m3, 250 million m3, and 60 million m3 respectively. © 2014 American Society of Civil Engineers.


Denaro G.,University of Palermo | Valenti D.,University of Palermo | Spagnolo B.,University of Palermo | Basilone G.,CNR Institute for Coastal Marine Environment | And 4 more authors.
PLoS ONE | Year: 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 the cell concentrations of the two picophytoplankton groups. The results are converted into chlorophyll a and divinil chlorophyll a concentrations and compared with experimental data collected in two different sites of the Sicily Channel (southern Mediterranean Sea). The comparison shows that real distributions are well reproduced by theoretical profiles. Specifically, position, shape and magnitude of the theoretical deep chlorophyll maximum exhibit a good agreement with the experimental values. © 2013 Denaro et al.

Discover hidden collaborations