1,720,998 research outputs found
Macroalgae transplant to detect the occurrence of anthropogenic nutrients in seawater of highly tourist beaches in Mediterranean islands
Full text linkIn the Mediterranean region, islands are among the most important tourist destinations, being sites of considerable naturalistic, historical and cultural importance. This is highly beneficial for local economies, but may also represent a threat for the environment, especially during the peak season (i.e. summer). Indeed, the sharp demographic increase concentrated in a relatively short period may negatively affect the quality of coastal marine systems and the provision of ecosystem services, producing in turn negative feedbacks on tourism industry. Nevertheless, the assessment of the environmental impact of tourism on coastal seawater has been seldom addressed. Here, we show the results of the biomonitoring approach adopted in the tourist Island of Rhodes (Greece), in the context of the Interreg Med BLUEISLANDS project. The study involved short-term macroalgae transplantation and incubation, and, through the analysis of nitrogen stable isotopes, provided a time-integrated picture of the occurrence of anthropogenic nutrients, which are indicators of water quality and might be missed by routine water quality monitoring programs. Main findings ruled out a marked input of anthropogenic nutrients potentially threatening the functioning of coastal ecosystems and highlighted overall good environmental conditions. In addition, this approach provided spatial data useful to produce GIS maps, useful tools that may help the decisional process of policy-makers, for adopting management practices to mitigate the environmental impact and foster sustainable touris
Evidences on alterations in skeleton composition and mineralization in a site-attached fish under naturally acidified conditions in a shallow CO2 vent
No full textBackground: Ocean acidification may affect fish mineralized structures (i.e. otoliths and skeleton).
Methods: Here,we compared the elemental composition of muscle and skeleton and themineral features of skeleton in the site-attached fish Gobius bucchichi naturally exposed to high pCO2/lowpH conditions in a shallow CO2 vent with fish of the same species exposed to normal pH.
Results: Overall, no skeleton malformations were found in both pH conditions, but among-site differences were
found in the elemental composition. Interestingly, higher Ca/P values, inducing a moderate skeleton maturation,
were found in fish exposed to acidified conditions than in controls.
Conclusion: Our findings suggest that ocean acidification may play a significant role in physiological processes related
to mineralization, fostering skeleton pre-aging
Discovering a beach “cemetery” of a seagrass Posidonia oceanica barrier reef: search for clues to reconstruct its origins
Full text linkBarrier reefs are peculiar structures of high ecological importance formed by the Mediterranean seagrass Posidonia
oceanica in very shallow areas through the accretion of biogenic matte. This study reports for the first time
the multiple discovery of several matte blocks of P. oceanica stranded on the southern coast of Sicily (central
Mediterranean) in front of a barrier reef. Unmanned Aerial Vehicle (UAV) mapping of the barrier reef and
morphological analysis of the blocks made it possible to hypothesise that the original substrate of the stranded
blocks was rocky, and that the colonisation of this substrate may have been facilitated by boring bivalve molluscs
through a so far unexplored plant-animal interaction. Furthermore, the indirect estimation of the theoretical
bathymetric origin of the blocks through a shoot density depth model, combined with the retrospective analysis
of the time series of the wave regime prior to stranding, suggests that a severe storm caused this collective
uprooting and stranding event from very shallow depths, raising new questions about the vulnerability of these
important ecosystems to the increase in frequency and intensity of storms expected in the climate change
scenarios
Ontogenetic trophic segregation between two threatened smooth-hound sharks in the Central Mediterranean Sea
Full text linkElasmobranchs are among the species most threatened by overfishing and a large body of evidence
reports their decline around the world. As they are large predators occupying the highest levels of
marine food webs, their removal can alter the trophic web dynamic through predatory release effects
and trophic cascade. Suitable management of threatened shark species requires a good understanding
of their behaviour and feeding ecology. In this study we provide one of the first assessments of the
trophic ecology of the “vulnerable” smooth-hounds Mustelus mustelus and M. punctulatus in the
Central Mediterranean Sea, based on stomach contents and stable isotope analyses. Ontogenetic
diet changes were addressed by comparing the feeding habits of three groups of individuals:
juveniles, maturing and adults. Our results highlighted that the two species share a similar diet based
mostly on the consumption of benthic crustaceans (e.g. hermit crabs). Their trophic level increases
during ontogeny, with adults increasing their consumption of large-sized crustaceans (e.g. Calappa
granulata, Palinurus elephas), cephalopods (e.g. Octopus vulgaris) and fish (e.g. Trachurus trachurus).
Our results provide also evidence of ontogenetic shifts in diet for both species showing a progressive
reduction of interspecific trophic overlap during growth. The results of this study contribute to
improve the current knowledge on the trophic ecology of these two threatened sharks in the Strait of
Sicily, thus providing a better understanding of their role in the food web
Trophic connections by means of biotic factors in transitional areas
No full textLe aree di transizione sono sistemi naturali d’interfaccia di elevato valore ecologico, strettamente connessi agli ambienti adiacenti tramite flussi di materia ed energia. Tuttavia, la conoscenza dei meccanismi e degli effetti innescati dalla connettività tra sistemi adiacenti risulta ancora alquanto limitata, specialmente per quanto concerne il ruolo del biota. La grande eterogeneità e la complessità delle aree di transizione rende, inoltre, impossibile una generalizzazione ed implica pertanto la scelta di oculate ipotesi e adeguate tecniche d’indagine in grado di comprendere le dinamiche che si innescano nelle diverse realtà ecologiche.
Al fine di valutare il ruolo dei fattori biotici come potenziale veicolo di materia organica, nutrienti e contaminanti tra sistemi adiacenti di diverse aree di transizione, nell’ambito di questa tesi di dottorato, sono state scelte due diverse aree di studio, una mediterranea, i laghetti di Marinello (Sicilia, Italia), ed una tropicale, Gazi Bay (Mombasa, Kenya), che rappresentano modelli di aree indipendenti in cui testare le ipotesi ecologiche. Attraverso l’uso congiunto di diversi approcci, quali lo studio del trofismo di acque e sedimenti, dei marker trofici e dei contaminanti ambientali, è stato possibile indagare gli obiettivi specifici scelti in relazione alle diverse peculiarità e dinamiche ecologiche delle aree di studio.
Nell’area mediterranea dei laghetti di Marinello (Sicilia, Italia) la struttura ed il funzionamento dei vari laghetti sono risultati profondamente influenzati dalla presenza di una colonia di gabbiani che rappresenta un’importante fonte di input alloctoni (guano).
Nelle stazioni maggiormente interessate dall’influenza dell’input aviario sono stati osservati un incremento della produttività primaria e del carico organico, bassi livelli di diversità delle comunità macrobentoniche con la dominanza di specie opportuniste, una struttura trofica complessivamente orientata verso l’uso del fitoplancton rispetto al fitobenthos ed elevati livelli di contaminazione ambientale.
Nell’area tropicale di Gazi Bay (Mombasa, Kenya) è emersa una notevole importanza degli habitat di back-reef come aree di alimentazione e nascondiglio per i giovanili di specie ittiche piuttosto che l’habitat a mangrovie, più importante, invece, come feeding ground per gli adulti. Diverse specie, tra le più importanti economicamente, hanno inoltre dato indicazioni, specialmente nella fase adulta, di effettuare migrazioni alimentari e/o ontogenetiche tra le mangrovie ed il coral reef supportando così alti livelli di connettività inter-habitat.
Mentre in letteratura è assodato il ruolo delle forzanti abiotiche nell’influenzare le dinamiche ecosistemiche costiere, dalla presente tesi emerge che nelle aree di transizione i fattori biotici giocano un forte ruolo nel connettere i sistemi adiacenti, secondo modalità strettamente legate alle caratteristiche intrinseche dei relativi sistemi, ma le cui conseguenze si ripercuotono comunque sui processi trofici e più in generale ecosistemici.Transitional areas are interface natural systems, featured by a high ecological value and strictly linked to adjacent habitats through flows of materials and energy. However, the knowledge of both mechanisms and effects of inter-habitat connectivity is still limited, especially about the role of biota. Further, both elevated heterogeneity and complexity of transitional areas make impossible to generalize trends and patterns, need the choice of careful hypotheses to be tested and appropriate techniques to understand the specific dynamics of the different ecological contexts.
In order to evaluate the role of biotic factors as possible carriers of organic matter, nutrients and contaminants between adjacent habitats of transitional areas, two study areas were chosen: a Mediterranean area, the Marinello ponds (Sicily, Italy) and a Tropical area, Gazi Bay (Mombasa, Kenya), representing two independent models of areas where to test the specific ecological hypotheses. By the combined use of several approaches, as the study of trophic status of water and sediment, the study of trophic markers and environmental contaminants, it was possible to fulfill the objectives relating to the different ecological features and dynamics of study areas.
In the Mediterranean area, the pond structure and functioning were highly influenced by the presence of a seagull colony, important source of allochtonous input (guano). Increased primary productivity and organic load, low levels of biodiversity of macrozoobentonic communities and dominance of opportunistic species, trophic structure shifted towards the use of phytoplankton more than to phytobenthos and high levels of environmental contamination were found in the sites more influenced by the avian input.
In the Tropical area of Gazi Bay (Mombasa, Kenya), a high importance of back-reef habitat as feeding ground and refuge area for juveniles of fish was found. Instead, the mangrove habitat was more important as feeding ground for adult fish. Several species, among the more commercially important in the area, gave evidence to carry out feeding and ontogenetic migrations between mangroves and coral reef, supporting a high level of inter-habitat connectivity.
While the role of abiotic factors in influencing ecosystem dynamics of coastal areas is well recognized in the literature, in this thesis we show that, in transitional areas, the biotic factors play an important role in connecting adjacent systems in a way strictly linked to the specific features of the areas, but raising consequences that affect anyway the trophic and ecosystem processes
Trophic connections by means of biotic factors in transitional areas
No full textLe aree di transizione sono sistemi naturali d’interfaccia di elevato valore ecologico, strettamente connessi agli ambienti adiacenti tramite flussi di materia ed energia. Tuttavia, la conoscenza dei meccanismi e degli effetti innescati dalla connettività tra sistemi adiacenti risulta ancora alquanto limitata, specialmente per quanto concerne il ruolo del biota. La grande eterogeneità e la complessità delle aree di transizione rende, inoltre, impossibile una generalizzazione ed implica pertanto la scelta di oculate ipotesi e adeguate tecniche d’indagine in grado di comprendere le dinamiche che si innescano nelle diverse realtà ecologiche.
Al fine di valutare il ruolo dei fattori biotici come potenziale veicolo di materia organica, nutrienti e contaminanti tra sistemi adiacenti di diverse aree di transizione, nell’ambito di questa tesi di dottorato, sono state scelte due diverse aree di studio, una mediterranea, i laghetti di Marinello (Sicilia, Italia), ed una tropicale, Gazi Bay (Mombasa, Kenya), che rappresentano modelli di aree indipendenti in cui testare le ipotesi ecologiche. Attraverso l’uso congiunto di diversi approcci, quali lo studio del trofismo di acque e sedimenti, dei marker trofici e dei contaminanti ambientali, è stato possibile indagare gli obiettivi specifici scelti in relazione alle diverse peculiarità e dinamiche ecologiche delle aree di studio.
Nell’area mediterranea dei laghetti di Marinello (Sicilia, Italia) la struttura ed il funzionamento dei vari laghetti sono risultati profondamente influenzati dalla presenza di una colonia di gabbiani che rappresenta un’importante fonte di input alloctoni (guano).
Nelle stazioni maggiormente interessate dall’influenza dell’input aviario sono stati osservati un incremento della produttività primaria e del carico organico, bassi livelli di diversità delle comunità macrobentoniche con la dominanza di specie opportuniste, una struttura trofica complessivamente orientata verso l’uso del fitoplancton rispetto al fitobenthos ed elevati livelli di contaminazione ambientale.
Nell’area tropicale di Gazi Bay (Mombasa, Kenya) è emersa una notevole importanza degli habitat di back-reef come aree di alimentazione e nascondiglio per i giovanili di specie ittiche piuttosto che l’habitat a mangrovie, più importante, invece, come feeding ground per gli adulti. Diverse specie, tra le più importanti economicamente, hanno inoltre dato indicazioni, specialmente nella fase adulta, di effettuare migrazioni alimentari e/o ontogenetiche tra le mangrovie ed il coral reef supportando così alti livelli di connettività inter-habitat.
Mentre in letteratura è assodato il ruolo delle forzanti abiotiche nell’influenzare le dinamiche ecosistemiche costiere, dalla presente tesi emerge che nelle aree di transizione i fattori biotici giocano un forte ruolo nel connettere i sistemi adiacenti, secondo modalità strettamente legate alle caratteristiche intrinseche dei relativi sistemi, ma le cui conseguenze si ripercuotono comunque sui processi trofici e più in generale ecosistemici.Transitional areas are interface natural systems, featured by a high ecological value and strictly linked to adjacent habitats through flows of materials and energy. However, the knowledge of both mechanisms and effects of inter-habitat connectivity is still limited, especially about the role of biota. Further, both elevated heterogeneity and complexity of transitional areas make impossible to generalize trends and patterns, need the choice of careful hypotheses to be tested and appropriate techniques to understand the specific dynamics of the different ecological contexts.
In order to evaluate the role of biotic factors as possible carriers of organic matter, nutrients and contaminants between adjacent habitats of transitional areas, two study areas were chosen: a Mediterranean area, the Marinello ponds (Sicily, Italy) and a Tropical area, Gazi Bay (Mombasa, Kenya), representing two independent models of areas where to test the specific ecological hypotheses. By the combined use of several approaches, as the study of trophic status of water and sediment, the study of trophic markers and environmental contaminants, it was possible to fulfill the objectives relating to the different ecological features and dynamics of study areas.
In the Mediterranean area, the pond structure and functioning were highly influenced by the presence of a seagull colony, important source of allochtonous input (guano). Increased primary productivity and organic load, low levels of biodiversity of macrozoobentonic communities and dominance of opportunistic species, trophic structure shifted towards the use of phytoplankton more than to phytobenthos and high levels of environmental contamination were found in the sites more influenced by the avian input.
In the Tropical area of Gazi Bay (Mombasa, Kenya), a high importance of back-reef habitat as feeding ground and refuge area for juveniles of fish was found. Instead, the mangrove habitat was more important as feeding ground for adult fish. Several species, among the more commercially important in the area, gave evidence to carry out feeding and ontogenetic migrations between mangroves and coral reef, supporting a high level of inter-habitat connectivity.
While the role of abiotic factors in influencing ecosystem dynamics of coastal areas is well recognized in the literature, in this thesis we show that, in transitional areas, the biotic factors play an important role in connecting adjacent systems in a way strictly linked to the specific features of the areas, but raising consequences that affect anyway the trophic and ecosystem processes.ope
Il macrozoobenthos: uno dei possibili descrittori di stato ecologico nel monitoraggio delle aree di transizione siciliane.
No full textTrace elements and stable isotopes in penguin chicks and eggs. A baseline for monitoring the Ross Sea MPA and trophic transfer studies
No full textMulti-tissue trace elements (TEs), C, N concentrations and stable isotopes (δ13C, δ15N) of chick carcasses and eggs of Adélie and Emperor penguins were studied to i) provide reference data before the recent institution of the Ross Sea Marine Protected Area (Antarctica), and ii) provide conversion factors that allow estimating C, N, δ13C and δ15N in edible tissues from non-edible ones, thus improving the use of stable isotopes in contamination and trophic transfer studies. Higher concentrations of As, Cd, Cr, Cu, Hg, Mn and Pb were found in chick carcasses than in eggs, suggesting increasing contamination in recent decades and high toxicity risks for penguin consumers. Isotopic conversion factors highlighted small differences among body tissues and conspecifics. These values suggest that chick carcasses are reliable indicators of the energy pathways underlying the two penguin species, their trophic position in the food web and their exposure to TEs
3D-Reconstruction of a Giant Posidonia oceanica Beach Wrack (Banquette): Sizing Biomass, Carbon and Nutrient Stocks by Combining Field Data With High-Resolution UAV Photogrammetry
Full text linkBeach wracks are temporary accumulations of vegetal detritus that can be found along
coastlines all over the world. Although beach wracks are often perceived as a nuisance for
beach users, they play a crucial ecological role in carbon and nutrient connectivity across
ecosystem boundaries, especially when they reach a relevant size, as in the case of the
wedge-shaped seagrass accumulations called banquette. In this study, threedimensional
mapping of a giant Posidonia oceanica banquette was carried out for the
first time using high-resolution UAV photogrammetry combined with field sampling and
compositional and chemical analysis. The combined approach allowed a reliable
estimation of the amount and spatial distribution of both vegetal biomass and
sedimentary mass, as well as of total carbon, nitrogen and phosphorus content,
revealing that i) banquette act as a sediment trap and represent hot spots of seagrass
biomass and carbon accumulation; ii) banquette thickness, rather than the distance from
the sea, influences the spatial distribution of all variables. Moreover, high-resolution digital
elevation models (DEM) revealed discontinuous patterns in detritus accumulation resulting
in an unknown banquette type here termed “Multiple Mega-Ridge banquette” (MMR
banquette). On the one hand, this study highlighted the high potential of the UAV
approach in very accurately 3D mapping and monitoring of these structures, with
relevant implications for ecosystem service estimation and coastal zone management.
On the other hand, it opened new questions about the role played by temporary beach
wracks and, in particular, by P. oceanica banquette in the blue carbon exchange across
land-ocean boundaries
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