Search results for "oceanography"

Automatic Acoustic Target Detecting and Tracking on the Azimuth Recording Diagram with Image Processing Methods

2019

International audience; Passive acoustic target detection has been a hot research topic for a few decades. Azimuth recording diagram is one of the most promising techniques to estimate the arrival direction of the interested signal by visualizing the sound wave information. However, this method is challenged by the random ambient noise, resulting in low reliability and short effective distance. This paper presents a real-time postprocessing framework for passive acoustic target detection modalities by using a sonar array, in which image processing methods are used to automate the target detecting and tracking on the azimuth recording diagram. The simulation results demonstrate that the prop…

A scenario-based assessment of the tsunami hazard in Palermo, northern Sicily, and the southern Tyrrhenian Sea

2020

Enrichment, isolation and biodegradation potential of psychrotolerant polychlorinated-biphenyl degrading bacteria from the Kongsfjorden (Svalbard Isl…

2016

Persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), have been detected in abiotic Arctic matrices: surface sediments and seawater from coastal areas in the Kongsfjorden were collected and analyzed. Levels of PCBs varied depending on the sampling site. Total PCB concentrations were between 11.63 (site C2W) and 27.69 pg l-1 (site AW). These levels were comparable to those reported previously in lake sediments from the northern Svalbard. The occurrence and biodegradation potential of cold-adapted PCB-oxidizing bacteria in seawater and sediment along the fjord was also evaluated. After enrichment with biphenyl, 246 isolates were obtained with 45 of them that were abl…

Nickel toxicity in P. lividus embryos: Dose dependent effects and gene expression analysis.

2018

Abstract Many industrial activities release Nickel (Ni) in the environment with harmful effects for terrestrial and marine organisms. Despite many studies on the mechanisms of Ni toxicity are available, the understanding about its toxic effects on marine organisms is more limited. We used Paracentrotus lividus as a model to analyze the effects on the stress pathways in embryos continuously exposed to different Ni doses, ranging from 0.03 to 0.5 mM. We deeply examined the altered embryonic morphologies at 24 and 48 h after Ni exposure. Some different phenotypes have been classified, showing alterations at the expenses of the dorso-ventral axis as well as the skeleton and/or the pigment cells…

Response to metals treatment of Fra1, a member of the AP-1 transcription factor family, in P. lividus sea urchin embryos

2018

Abstract Lithium (Li), Nickel (Ni), and Zinc (Zn) are metals normally present in the seawater, although they can have adverse effects on the marine ecosystem at high concentrations by interfering with many biological processes. These metals are toxic for sea urchin embryos, affecting their morphology and developmental pathways. In particular, they perturb differently the correct organization of the embryonic axes (animal-vegetal, dorso-ventral): Li is a vegetalizing agent and Ni disrupts the dorso-ventral axis, while Zn has an animalizing effect. To deeply address the response of Paracentrotus lividus embryos to these metals, we studied the expression profiling of Pl-Fra transcription facto…

Effects of exposure to gadolinium on the development of geographically and phylogenetically distant sea urchins species.

2016

Gadolinium (Gd), a metal of the lanthanide series used as contrast agent for magnetic resonance imaging, is released into the aquatic environment. We investigated the effects of Gd on the development of four sea urchin species: two from Europe, Paracentrotus lividus and Arbacia lixula, and two from Australia, Heliocidaris tuberculata and Centrostephanus rodgersii. Exposure to Gd from fertilization resulted in inhibition or alteration of skeleton growth in the plutei. The similar morphological response to Gd in the four species indicates a similar mechanism underlying abnormal skeletogenesis. Sensitivity to Gd greatly varied, with the EC50 ranging from 56 nM to 132 μM across the four species…

Microbial communities of polluted sub-surface marine sediments

2018

Abstract Microbial communities of coastal marine sediment play a key role in degradation of petroleum contaminants. Here the bacterial and archaeal communities of sub-surface sediments (5–10 cm) of the chronically polluted Priolo Bay (eastern coast of Sicily, Italy), contaminated mainly by n-alkanes and biodegraded/weathered oils, were characterized by cultural and molecular approaches. 16S-PCR-DGGE analysis at six stations, revealed that bacterial communities are highly divergent and display lower phylogenetic diversity than the surface sediment; sub-surface communities respond to oil supplementation in microcosms with a significant reduction in biodiversity and a shift in composition; the…

Gonadal sexual differentiation of European sea bass (Dicentrarchus labrax, L. 1758) of fingerlings in different size classes

2016

This report describes a study of the gonad differentiation in fingerlings of European sea bass (Dicentrarchus labrax) belonging to different size groups. Fishes were divided into four groups according to their weight: Group 1 (4.5 ± 0.7 g), Group 2 (9.2 ± 0.8 g), Group 3 (14.8 ± 1.8 g), and Group 4 (21.8 ± 2.3 g). In all groups, low percentages of undifferentiated or early sexually differentiated fish were found. Higher percentages of fully differentiated ovaries were found in Groups 1 and 3. Fully differentiated testes occurred in 90% of Group 4. Ninety percent of fish in Group 2 had gonads with intratesticular oocytes. This highlights the occurrence of intersexual cases and suggests that …

Anisakis infections in lantern fish (Myctophidae) from the Arabian Sea: A dual role for lantern fish in the life cycle of Anisakis brevispiculata?

2018

Abstract Data on geographic distribution and life cycles of parasitic nematodes of the genus Anisakis in tropical oceanic regions are extremely scarce. Myctophids (lantern fishes) are a key component of mesopelagic trophic webs and could play a significant role in the transmission of Anisakis spp. in these regions. We examined Anisakis infections in a sample of 160 myctophids collected in three localities from the Indian Exclusive Economic Zone (Arabian Sea) in 2015–16. Due to the poor condition of fish, a combination of morphological data and molecular barcoding was used to identify myctophids. Of the 104 specimens that could be identified at least to genus level, 75 (72.1%) were assigned …

Settlement performance of the Mediterranean reef-builders Dendropoma cristatum (Biondi 1859) in response to natural bacterial films.

2017

The gastropod Dendropoma cristatum is a biogenic engineer of the central Mediterranean, forming reefs along the lower rocky intertidal fringe with a remarkable ecological role. To understand whether reef-associated biofilm cultivable bacterial and biofilm ageing may trigger the settlement of the juvenile snails, a combination of laboratory techniques and field experiments was used. Reef-associated biofilm cultivable bacteria were isolated, and a settlement-choice experiment was performed in situ on artificial biofilms composed of i) a mixture of six biofilm-forming selected isolates, ii) all the cultivable bacteria, and iii) 13-, 23-, 32-day old biofilms formed under natural conditions. Ove…