1,720,997 research outputs found
Tide affects food availability in rock pools: evidence from Mediterranean intertidal habitats
No full textPatterns and drivers of meiofaunal assemblages in the canyons Polcevera and Bisagno of the Ligurian Sea (NW Mediterranean Sea)
No full textMeiofaunal abundance, assemblage structure and richness of higher taxa were investigated for the first time in two submarine canyons (Polcevera and Bisagno) of the Ligurian Sea and along the adjacent open slope, in relation with the quantity and quality of sedimentary organic matter and other environmental variables, including grain size. Meiofaunal abundance and richness of higher taxa decreased with increasing water depth (from ca. 200 down to ca. 2000-m depth) in the open slope and Polcevera canyon, whereas the highest values were observed at 500 m depth in the Bisagno canyon. The comparison between canyons and the adjacent open slope, showed the lack of significant differences in meiofaunal abundance, at the same depth except for samples collected at 200 and 2000-m depth. Overall the biodiversity was higher in canyons than in the open slope. Phytopigments, utilised as a proxy of the input of primary organic matter, were up to 3 times higher in canyon than in slope sediments and, along with grain size, explained a large portion of the variability in all meiofaunal variables. Canyon and slope showed a high beta diversity (83%), mostly due to the presence of a high portion of rare taxa in the canyons. Some taxa, such as Cladocera, Cumacea, Gastrotricha, Nemertina were exclusively encountered in canyon sediments, whereas Tardigrada were encountered only in the adjacent slope. Results reported here indicated that, differences in meiofaunal assemblages between canyons and slopes are primarily driven by quantity and quality of the available food resources and by the presence of specific topographic features
L’effetto della mitilicoltura posta a valle di allevamenti di specie ittiche riduce il carico organico
No full textL’utilizzo del mussel cleaning che sfrutta le caratteristiche fisiologiche dei molluschi filtratori per la mitigazione degli impatti derivanti da reflui particellati di origine antropica, ed in particolare delle attività di piscicoltura, è stato introdotto di recente in diversi paesi europei. Tale procedura si basa sull’ipotesi che la filtrazione operata da elevate biomasse di molluschi eduli posti nei pressi degli impianti di pescicoltura possa ridurre il carico organico in eccesso proveniente dal surplus di mangime fornito ai pesci allevati e che in certa parte inutilizzato tende a sedimentare al di sotto delle gabbie di allevamento. In questo studio abbiamo analizzato in due periodi differenti (Luglio e Ottobre 2006) le differenze nel carico e nella composizione biochimica del particellato in sospensione in siti posti nelle vicinanze di gabbie di allevamento di pesci associate a filari per l’allevamento di bivalvi (mitili ed ostriche) ed in siti di controllo lontani dalle gabbie ma caratterizzati dalla presenza di filari di molluschi. Né quantità né composizione biochimica del particellato sospeso differiscono significativamente tra siti interessati dai reflui della piscicoltura e relativi controlli. Questi risultati suggeriscono che la presenza di elevate biomasse di filtratori possa avere un certo effetto nella riduzione del carico organico associato ai reflui di maricoltura
La materia organica disponibile per i bivalvi filtratori nei laghetti di tindari (Sicilia Nord-Orientale)
No full textNovel green hybrid acidic-cyanide bioleaching applied for high recovery of precious and critical metals from spent light emitting diode lamps
No full textThe spent light emitting diode (LED) lamp is a new type of electronic waste contains the large amount of valuable metals. In this study, a novel green hybrid acidic-cyanide bioleaching process was developed for the high efficiency recovery of valuable metals from spent LED lamps. The spent LEDs were biopretreated using biogenic ferric produced by Acidithiobacillus ferrooxidans to efficiently harvest all base and heavy metals, 93% Sn, 94% Ni, 80% Cu, 68% Al, 60% Ga, 51% Pb, 46% Cr, and 35% Fe were leached. Then the bio-pretreated residue was bioleached by Bacillus megaterium (B. megaterium). Under optimum conditions (pH 7; glycine 2.5 g/L; L. methionine 10 g/L), 15 mg/L cyanide was produced by B. megaterium in short time of 14 h. At 10 g/L bio-pretreated spent LED, under direct hybrid bioleaching, a 47% gold extraction efficiency was observed after 36 h. The better performance of direct hybrid bioleaching suggests the important role of extracellular polymeric substances (EPS) and the continuous production of CN-. Compared to single cyanide bioleaching with un-pretreated LEDs, the amounts of metals recovered through hybrid direct bioleaching were significantly high; 93% Au, 91% Ag, 98% Ni, 87% Cu, and 84% Ga were leached after 4 d. This study developed an approach for the efficient recycling of spent LEDs that will result in a huge economic interest and better environmental performance. (c) 2021 Elsevier Ltd. All rights reserved
Anthropogenic noise and biological sounds in a heavily industrialized coastal area (Gulf of Naples, Mediterranean Sea)
No full textUnderwater noise is one of the most widespread threats to the world oceans. Its negative impact on fauna is nowadays well established, but baseline data to be used in management and monitoring programs are still largely lacking. In particular, the acoustic assessment of human-impacted marine coastal areas provides complementary information on the health status of marine ecosystems. The objective of our study was to provide a baseline of underwater noise levels and biological sounds at two sites within the Gulf of Naples (Italy), one of which is located in Bagnoli-Coroglio, a Site of National Interest (SIN) for its high contamination levels. Within the SIN, sounds were recorded both before and during sediment coring activities (vibrocorer sampling), in order to investigate the potential acoustic impact due to such operations. Acoustic recordings were analyzed following the European Marine Strategy Framework Directive indications as defined in the frame of the Descriptor 11. Results reported here show that the investigated area is characterized by a high anthropogenic noise pressure. Ambient noise levels were principally driven by shipping noise and biological sounds of invertebrates (e.g., snapping shrimps). Sounds referable to other biological activity were difficult to detect because heavily masked by shipping noise. Coring activity determined a substantial introduction of additional noise at a local spatial scale. This study expands underwater noise baseline data to be further implemented in future monitoring programs of coastal areas affected by anthropogenic impacts. In addition, it proposes new cues for using underwater acoustic monitoring tools to complement traditional methodologies for evaluating health status of ecosystems and for investigating recovery rates after restoration/reclamation programs
High potential for temperate viruses to drive carbon cycling in chemoautotrophy-dominated shallow-water hydrothermal vents
No full textViruses are the most abundant life forms in the world's oceans and they are key drivers of biogeochemical cycles, but their impact on the microbial assemblages inhabiting hydrothermal vent ecosystems is still largely unknown. Here, we analysed the viral life strategies and virus-host interactions in the sediments of a newly discovered shallow-water hydrothermal field of the Mediterranean Sea. Our study reveals that temperate viruses, once experimentally induced to replicate, can cause large mortality of vent microbes, significantly reducing the chemoautotrophic carbon production, while enhancing the metabolism of microbial heterotrophs and the re-cycling of the organic matter. These results provide new insights on the factors controlling primary and secondary production processes in hydrothermal vents, suggesting that the inducible provirus-host interactions occurring in these systems can profoundly influence the functioning of the microbial food web and the efficiency in the energy transfer to the higher trophic levels
Effetto dell’impatto antropico e geometria del substrato sulla distribuzione e struttura delle comunità bentoniche vegetali di fouling
No full textEffetti dell’impatto antropico e della geometria del substrato su struttura e distribuzione delle comunità bentoniche di fouling
No full textLocal food availability affects invasion ability of alien bivalves: an experimental and simulation integrated approach
No full textThe Lessepsian bivalve Brachidontes pharaonis is considered as one of 100 worst
invasive species in the Mediterranean rapidly colonizing the most part of the Basin. Its
current distribution seems primarily due to ship transport of carrying larvae by ballast
waters and/or in the fouling attached beneath the ship-keels. Although humanmediated
transport seems to potentially in!uence dispersal of invasive species, habitat
suitability, temperature, salinity and food availability (i.e. in terms of quality and quantity
of organic matter) seem to represent decisive factors in determining survivorship
and distribution of this species. Physiological tolerance of B. pharaonis to temperature
and salinity changes has been demonstrated to be very large, while scant information
available about its physiological response to food availability changes. In this paper, we
report the #rst experimental mesocosmal dataset on B. pharaonis’s scope for growth
(SFG) as a function of di"erent concentrations of chlorophyll-a from 0.9 – 1.0 to 3.9 – 4.0
μg l-1. B. pharaonis’s SFG varied from negative values at 0.1 μg l-1 [CHL-a] to positive
values at > 0.9 μg l-1 [CHL-a]. In addition, by interpolating , SFG data and large satellite
dataset of CHL-a values obtained from the Environmental Marine Information System
(EMIS), we estimated on a very small spatial scale (8.1 nmi) the potential dispersal and
distribution of this specie along Sicilian coastlines
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