1,720,976 research outputs found
Fattori di controllo della disponibilità alimentare per il benthos eterotrofo in ambienti costieri di interfaccia
No full textGli ecosistemi di interfaccia, sono rappresentati da tutti quegli habitat al confine tra terre
emerse continentali e ambienti acquatici. Essi sono la fase dinamica di incontro tra ambienti
largamente differenti (mare, terra, atmosfera) definita come “interfaccia”, nella quale è possibile
riconoscere la transizione da un sistema all’altro per la presenza di marcati gradienti fisico-chimici,
biologici ed ecologici. Nella fattispecie, questi ecosistemi sono rappresentati dagli ambienti costieri
di basso fondale e da ambienti intertidali di substrato duro. Essi sono i principali fornitori di beni e
servizi ecosistemici per le popolazioni costiere. In questa tesi si è studiato il ruolo della variabilità
sistemica in ambienti intertidali di bassofondo su alcuni aspetti salienti del funzionamento
ecosistemico, della biodiversità e in ultimis sulla relazione tra biodiversità e funzionamento
ecosistemico. L’obiettivo è stato quello di studiare l’effetto della variabilità fisica e chimica come
fattore di controllo nei due habitat modello (laguna e pozze intertidali) lungo le coste della Sicilia
nord-occidentale, sulle caratteristiche del cibo disponibile - proveniente da produzione primaria e
secondaria. I risultati di questo studio mettono in evidenza il ruolo determinante della variabilità
spaziale e temporale, la quale controlla ampiamente le dinamiche chimico fisiche e trofiche in
questi ambienti estremi. Ad esempio nello Stagnone di Marsala l’energia meccanica di attrito
innescata dalla sinergia vento/marea gioca un ruolo importante sulla disponibilità di cibo, favorendo
gli scambi tra il comparto sedimentario e la colonna d’acqua. La presenza di vegetazione smorza
l’entità degli scambi che divengono massimi quando le fanerogame marine sono rade o assenti. I
risultati degli esperimenti su gli ambienti di pozza, hanno dimostrato l’importanza di questi habitat
sotto molti aspetti. Le pozze di scogliera del Mediterraneo, le cui dinamiche fisiche e chimiche sono
azionate dalle escursioni mareali funzionano come veri e propri bio-reattori. In particolare, è stato
dimostrato che, ogni sei ore, per effetto dell’isolamento in emersione, le pozze di scogliera
triplicano il contenuto di materiale organico, il quale viene disperso nell’adiacente intertidale, al
momento del collegamento con il mare nella successiva alta marea. Dato l’elevatissimo numero di
pozze presenti lungo le coste rocciose, l’export di materia organica labile prodotta quotidianamente
è quantitativamente rilevante. Questo sink di energia contribuisce indubbiamente a favorire il
mantenimento degli elevati livelli di biodiversità tipici di questi ambienti del Mediterraneo.
I risultati di questo studio forniscono nuove informazioni utili alla comprensione del funzionamento
degli ecosistemi di interfaccia marino-costieri, che sono stati fino ad ora, la fonte più importante di
approvvigionamento per le popolazioni rivierasche di tutto il pianeta
La materia organica disponibile per i bivalvi filtratori nei laghetti di tindari (Sicilia Nord-Orientale)
No full textHigh diversity of benthic bacterial and archaeal assemblages in deep-Mediterranean canyons and adjacent slopes
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Organic enrichment can increase the impact of microplastics on meiofaunal assemblages in tropical beach systems
Full text linkThe cumulative impact of microplastic and organic enrichment is still largely unknown. Here, we investigated the microplastic contamination, the organic enrichment and their effects on meiofaunal distribution and diversity in two islands of the Maldivian archipelago: one more pristine, and another strongly anthropized. Field studies were coupled with manipulative experiments in which microplastic polymers were added to sediments from the non-anthropized island (i.e., without organic enrichment) to assess the relative effect of microplastic pollution on meiofauna assemblages. Our results reveal that the impact of microplastic contamination on meiofaunal abundance and taxa richness was more significant in the anthropized island, which was also characterized by a significant organic enrichment. Meiofauna exposed experimentally to microplastic contamination showed: i) the increased abundance of opportunistic nematodes and copepods and ii) a shift in the trophic structure, increasing relevance in epistrate-feeder nematodes. Based on all these results, we argue that the coexistence of chronic organic enrichment and microplastics can significantly increase the ecological impacts on meiofaunal assemblages. Since microplastic pollution in the oceans is predicted to increase in the next decades, its negative effects on benthic biodiversity and functioning of tropical ecosystems are expected to worsen especially when coupled with human-induced eutrophication. Urgent actions and management plans are needed to avoid the cumulative impact of microplastic and organic enrichment
Biodiversity and distribution of meiofauna in the Gioia, Petrace and Dohrn Canyons (Tyrrhenian Sea)
No full textHabitat heterogeneity is a major structuring agent of benthic assemblages promoting high turnover in species composition and ultimately contributing to overall higher diversity. Submarine canyons, a pervasive feature of the continental margins worldwide, increase habitat heterogeneity at multiple spatial scales. In the present study, we test the hypothesis that different topographic structures or/and food sources controlling the abundance, biomass and biodiversity (using meiofauna and nematodes as a model study) in canyon systems. To do so, we compared different topographic structures: canyon edge, thalweg and axis, and the upper shelf and open slope in the Gulf of Gioia (Gioia and Petrace Canyons) and in the Gulf of Naples (Dohrn Canyon) (Tyrrhenian Sea) at different depths. Our results suggest that meiofaunal abundance and biomass are generally higher in the canyon thalwegs than in the canyon edge or adjacent open slopes at regional scale. This pattern is not always confirmed for biodiversity and when thalwegs are compared to different topographic structures within the Gioia Canyon system. In our study, the role of food quantity and quality is preeminent to explain the spatial distribution of meiofaunal variables among different topographic structures at 200-m while habitat heterogeneity become relevant at 500-m and within the Dohrn Canyon. In Gioia and Petrace Canyons we observed a high food availability is associated to specific topographic structures (thalwegs) that influenced the meiofaunal abundance and diversity distribution and nematode diversity and species composition. Each topographic structure shows a high number of exclusive species that contributes to a high species turnover and high overall biodiversity in all canyon systems. Changes in nematode composition determine also differences in the functional diversity (trophic guilds composition) and life strategy of the nematode assemblages. Our findings reveal that the presence of different topographic structures influences the spatial distribution of food quality and quantity that determine the presence of exclusive taxa and species enhancing both local and regional diversity
Impact of breakwater relocation on benthic biodiversity associated with seagrass meadows of northern Adriatic Sea
No full textBreakwaters are man-made constructions utilized for preventing coastal erosion primarily from wave action. At the same time, defence structures, modifying currents and circulation can afect water quality and benthic assemblages. Assessing and minimizing the impact of these structures is a priority in human-modifed coastal ecosystems, such as the central northern Adriatic where breakwaters extend for hundreds of kilometres. We investigated the efects of breakwater relocation on benthic features and meiofaunal diversity. To do this, we conducted a before–after comparison of (2011–2017) the relocation, which occurred in 2015. The analysis was conducted comparing a sheltered site, characterized by the presence of seagrass meadows and a wave-exposed site. Sediment features and meiofaunal variables were altered by the relocation, especially in the areas colonized by seagrass meadows. Results presented here pointed out to an enrichment in organic matter, the loss of two sensitive taxa (Cumacea and Ostracoda) and a shift in the assemblage structure with the increase of the relevance of Copepoda and Polychaeta. These results indicate that the careful management of breakwater is crucial for planning adequate conservation practices and protecting seagrass habitats and their biodiversity.This study has been conducted in the framework of the Project MERCES funded from the European Union's Horizon
2020 research and innovation programme under Grant agreement no. 689518.
This paper reflects only the authors' views and the funders cannot be held responsible for any use that may be made of the information contained there in. Copyright © 2018. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC-BY) license (http:// creativecommons.org /licenses/by/4.0/)
Microbiome network in the pelagic and benthic offshore systems of the northern Adriatic Sea (Mediterranean Sea)
Full text linkBecause of their recognized global importance, there is now the urgent need to map diversity and distribution patterns of marine microbial communities. Even if available studies provided some advances in the understanding the biogeographical patterns of marine microbiomes at the global scale, their degree of plasticity at the local scale it is still underexplored, and functional implications still need to be dissected. In this scenario here we provide a synoptical study on the microbiomes of the water column and surface sediments from 19 sites in a 130 km(2) area located 13.5 km afar from the coast in the North-Western Adriatic Sea (Italy), providing the finest-scale mapping of marine microbiomes in the Mediterranean Sea. Pelagic and benthic microbiomes in the study area showed sector specific-patterns and distinct assemblage structures, corresponding to specific variations in the microbiome network structure. While maintaining a balanced structure in terms of potential ecosystem services (e.g., hydrocarbon degradation and nutrient cycling), sector-specific patterns of over-abundant modules—and taxa—were defined, with the South sector (the closest to the coast) characterized by microbial groups of terrestrial origins, both in the pelagic and the benthic realms. By the granular assessment of the marine microbiome changes at the local scale, we have been able to describe, to our knowledge at the first time, the integration of terrestrial microorganisms in the marine microbiome networks, as a possible natural process characterizing eutrophic coastal area. This raises the question about the biological threshold for terrestrial microorganisms to be admitted in the marine microbiome networks, without altering the ecological balance
CO2 leakage from carbon dioxide capture and storage (CCS) systems affects organic matter cycling in surface marine sediments
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