102,401 research outputs found
Gold coral (Savalia savaglia) and gorgonian forests enhance benthic biodiversity and ecosystem functioning in the mesophotic zone
No full textThe twilight or mesophotic zone is among the less explored marine regions. In coastal areas, investigations and manipulative experiments on benthic biodiversity and ecosystem functioning at depths up to >50m have been recently made possible by the progress of SCUBA techniques. In this study, we tested the effects of the presence of a gorgonian forest characterised by a large and dense population of the gold coral Savalia savaglia (Bertoloni 1819) on the benthic biodiversity (nematode species richness, and meiofauna community structure and richness of taxa), trophic guilds state (molluscs) and ecosystem functioning in the surrounding sediments. The S. savaglia colonies create elevated and complex tertiary structures. Our results indicate that the presence of these colonies was associated with a significantly increased deposition of bioavailable substrates and enhanced biodiversity, when compared with soft bottoms at the same depth but without gold corals. The higher biodiversity and altered trophic conditions resulted in higher rates of ecosystem functioning (e.g., higher benthic biomasses). These results suggest that S. savaglia should be particularly protected not only for its specific rarity, endemism and vulnerability but also because has a prominent role in sustaining high levels of biodiversity and ecosystem functioning in the surrounding benthos of the twilight zone
The trophic biology of the holothurian Molpadia musculus: implications for organic matter cycling and ecosystem functioning in a deep submarine canyon
No full textMegafaunal organisms play a key role in ecosystem functioning in the deep-sea through bioturbation, bioirrigation and organic matter cycling. At 3500 m water depth in the Nazaré Canyon, NE Atlantic, very high abundances of the infaunal holothurian Molpadia musculus were observed. To quantify the role of M. musculus in sediment cycling, sediment samples and holothurians were collected using an ROV and in situ experiments were conducted with incubation chambers. The biochemical composition of the sediment (in terms of proteins, carbohydrates and lipids), the holothurians' gut contents and holothurians' faecal material were analysed. In the sediments, proteins were the dominant organic compound, followed by carbohydrates and lipids. In the holothurian's gut contents, protein concentrations were higher than the other compounds, decreasing significantly as the material passed through the digestive tract. Approximately 33±1% of the proteins were digested by the time sediment reached the mid gut, with a total digestion rate equal to 67±1%. Carbohydrates and lipids were ingested in smaller amounts and digested with lower efficiencies (23±11% and 50±11%, respectively). As a result, the biopolymeric C digestion rate was on average 62±3%. We estimated that the population of M. musculus could remove approximately 0.49±0.13 g biopolymeric C and 0.13±0.03 g N m?2 d?1 from the sediments. These results suggest that M. musculus plays a key role in the benthic tropho-dynamics and biogeochemical processes in the Nazaré Canyon.<br/
Scope For Growth of Mytilus galloprovincialis (Lmk., 1819) in oligotrophic coastal waters (southern Tyrrhenian Sea, Italy)
No full textThe ‘scope for growth’ (SFG) tool was used to
study the growth performance of cultivated populations of
Mytilus galloprovincialis (Lmk., 1819) in an oligotrophic
area of the Southern Mediterranean Sea. The study was
carried out between 1993 and 1996 by using data from four
seasonal oceanographic cruises and from growth experiments.
Water samples were collected and analysed for total
suspended matter (TSM), particulate organic carbon (POC)
and nitrogen (PON), particulate lipids, proteins and carbohydrates
and chloropigments. The sum of the carbon
equivalents of carbohydrates, proteins and lipids is indicated
as the total biopolymeric particulate organic carbon
(BPC) and was converted into a unit of energy in order to
calculate the SFG of a theoretical mussel of 5 cm length. In
order to test the performance of mussel growth at two
depths (5 and 15 m water depth), mussel body size [as ash
free dry weight (AFDW)] and the actual concentrations
of BPC were used to calculate the monthly SFG using
the physiological energetic relationships suggested in the
current literature. Data from the field cruises led us to
characterise the study site as ultra-oligotrophic (annual
average of chloropigment concentration approximately
0.5 lg L-1). SFG calculations allowed us to identify a site
where mussels grown successively were found to reach a
commercial size in approximately 12 months. The good
agreement obtained between energetic response and subsequent
production response suggests that the available
energy from particulate food could be fully available for
organic production for maintaining ‘‘proportionate’’ growth
trajectories, even in a ultra-oligotrophic system
7. Albertelli G., Cattaneo-Vietti R., Chiantore M., Pusceddu A., Fabiano M. Food availability to an Adamussium bed during the austral summer 1993/1994 (Terra Nova Bay, Ross Sea)
No full textThe relationship between food availability and growth in Mytilus galloprovincialis in the open sea (southern Mediterranean)
No full textWith the aim of gathering information about the possibility of culturing mussels (Mytilus galloprovincialis) in a south Mediterranean oligotrophic area, different lots of mussels were placed in culture at depths of -5 m and -15 m and their growth monitored on a monthly basis. Temperature and salinity were measured in situ and water samples were collected at different depths each month. Total suspended matter (TSM) and its inorganic (ISM) and organic (OSM) fractions were analysed by gravimetry and loss on ignition. Photosynthetic pigments (chlorophyll-a and phaeopigments), particulate organic carbon (POC) and nitrogen (PON), particulate carbohydrate (CHO), protein (PRT) and lipid concentration (LIP) were also measured. The chlorophyll-a concentrations highlighted the high degree of oligotrophy of the study site. Moreover, the inorganic fraction of total seston, which exceeded the organic fraction throughout the study period, highlighted the importance of the allochthonous input of suspended particles. Two main phytoplankton abundance peaks were observed, in spring and autumn. These peaks were mirrored by the biochemical composition of the biopolymeric fraction of particulate organic matter (POM, the sum of PRT, CHO and LIP concentrations). The relatively high values of the POC:PON ratio indicated that the major fraction of particulate organic matter in the study area was of detrital origin. A clear dilution effect on the organic matter, caused by high concentrations of suspended inorganic material, was also revealed by the LPOM/TSM ratio, used as a qualitative food index. The mussels were found to activate physiological compensatory mechanisms in order to maintain a constant absorption rate of organic matter from the total available seston. In this case study, the mussels survived in an environment in which the quantities of available food were frequently time-varied. The mussels placed in culture as juveniles (total length = 11.20 ± 4.02 mm) reached a length of approximately 40 mm after 12 months, while the mussels placed in culture as sub-adults (total length = 43.16 ± 7.5 mm) reached the commercial size of about 60 mm in the same time interval. The sub-adult mussels spawned in autumn and spring, indicating that they acclimatised well, despite the high degree of oligotrophy of the water
Helicobacter Pylori detection in saliva with PCR real time: a new non invasive diagnostic method in primary care medicine
No full textThe relationship between food availability and the growth in Mytilus galloprovincialis in the open-sea (southern Mediterranean)
No full textWith the aim of gathering information about the possibility of culturing mussels (Mytilus galloprovincialis) in a south Mediterranean oligotrophic area, different lots of mussels were placed in culture at depths of -5 m and -15 m and their growth monitored on a monthly basis. Temperature and salinity were measured in situ and water samples were collected at different depths each month. Total suspended matter (TSM) and its inorganic (ISM) and organic (OSM) fractions were analysed by gravimetry and loss on ignition. Photosynthetic pigments (chlorophyll-a and phaeopigments), particulate organic carbon (POC) and nitrogen (PON), particulate carbohydrate (CHO), protein (PRT) and lipid concentration (LIP) were also measured. The chlorophyll-a concentrations highlighted the high degree of oligotrophy of the study site. Moreover, the inorganic fraction of total seston, which exceeded the organic fraction throughout the study period, highlighted the importance of the allochthonous input of suspended particles. Two main phytoplankton abundance peaks were observed, in spring and autumn. These peaks were mirrored by the biochemical composition of the biopolymeric fraction of particulate organic matter (POM, the sum of PRT, CHO and LIP concentrations). The relatively high values of the POC:PON ratio indicated that the major fraction of particulate organic matter in the study area was of detrital origin. A clear dilution effect on the organic matter, caused by high concentrations of suspended inorganic material, was also revealed by the LPOM/TSM ratio, used as a qualitative food index. The mussels were found to activate physiological compensatory mechanisms in order to maintain a constant absorption rate of organic matter from the total available seston. In this case study, the mussels survived in an environment in which the quantities of available food were frequently time-varied. The mussels placed in culture as juveniles (total length = 11.20 ± 4.02 mm) reached a length of approximately 40 mm after 12 months, while the mussels placed in culture as sub-adults (total length = 43.16 ± 7.5 mm) reached the commercial size of about 60 mm in the same time interval. The sub-adult mussels spawned in autumn and spring, indicating that they acclimatised well, despite the high degree of oligotrophy of the water
La ricerca dell’ Helicobacter pylori nella saliva mediante PCR real time:un nuovo test non invasivo per il medico di Medicina Generale
No full textDesulfomicrobium orale, nuova specie patogena? Indagine molecolare su prelievi parodontali
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