1,721,074 research outputs found
Atacama Trench International Expedition
No full textAlthough it has been recognized recently that deep-sea areas might be characterised by benthic “hot-spots”, research on trenches has so far recognized the oligotrophy of these environments both in terms of available food sources and density of benthic organisms. In September 1997, an international expedition promoted by the Istituto di Scienze Ambientali Marine of the University of Genova, involving European and Chilean institutions and with the cooperation of the Servicio Hydrográfico y Oceanográfico de la Armada de Chile, was carried out on board the vessel Vidal Gormaz to study the benthic ecology of the Atacama Trench, which, due to the extremely high productivity of the area, could present special characteristics
BOSICON 2009 - Second International Congress on Soil Remediation
No full textGuest Editor della Special Issue Vol. 27 / Supplement/ February 2011
ISSN 0275-754
The life cycle of Tiaropsidium roseum (Tiaropsidae fam. nov. Leptomedusae, Cnidaria)
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Sediment resuspension effects on the benthic microbial loop in experimental microcosm
No full textSediment resuspension induced by anthropogenic disturbance is becoming a major threat of marine coastal ecosystems worldwide. The effects of sediment resuspension on the pelagic domain and on macro- and meiobenthos are well documented in the literature, whereas the effects on the benthic microbial components are nearly neglected. We have investigated the effects of sediment resuspension at two different disturbance levels on benthic bacterial abundance, biomass, and activities and on heterotrophic nanobenthos abundance in experimental microcosms. The results of our experiments pointed out that, independently from the amount of involved energy, sediment resuspension determined a general decrease of all benthic microbial components. The main effects consisted of a decreased abundance of the metabolically active bacterial fraction and of heterotrophic nanobenthos abundance. However, the amount of energy involved in sediment resuspension had differential effects on the structure and functioning of the benthic microbial loop, but only in the short term (i.e., within 36 h). Sediment resuspension had a stimulatory effect on activities of surviving bacterial cells, which, in turn, resulted in increased sediment organic C turnover rates. We hypothesize that such an effect, enhancing nutrient availability, might have relevant consequences on the trophic state of coastal marine ecosystem
Enzymatic activities of epiphytic and benthic thraustochytrids involved in organic matter degradation
No full textThraustochytrids are marine osmo-heterotrophic protists which have been isolated from different habitats and substrates. These organisms are typically encountered in association with refractory substrates, but the extent of their role in organic matter decomposition is still unknown. We isolated 11 thraustochytrid strains from different substrates and tested all species for their potential constitutive ecto- (cell-surface associated) and exo- (free released) enzymatic activities. Our results indicate that the investigated strains exhibited a wide spectrum of enzymes involved in the hydrolysis of all classes of organic compounds, suggesting that thraustochytrids are capable of degrading a large variety of substrates. The enzymatic pools were similar among all strains, and exhibited a good production of lipase, a selection of protease and a poor pool of carbohydrate degradation enzymes. However, different isolates displayed different spectra and intensities of enzymatic activities. The comparison of enzymatic activities of 2 thraustochytrid strains and the total enzymatic activities measured in their natural substrates suggested that thraustochytrids, although representing a minor fraction of the total benthic microbial biomass, are contributors to the degradation of highly refractory organic compounds
Detritus rolling down a vertical cliff of the Ligurian Sea (Italy): the ecological role in hard bottom communities.
No full textResponse of BITS (a benthic index based on taxonomic sufficiency) to water and sedimentary variables and comparison with other indices in three Adriatic lagoons
No full textThe European Water Framework Directive (WFD, 2000 ⁄ 60 ⁄ EC) recommends
the development of biotic indices for assessing the ecological quality status of
water bodies. The Benthic Index based on Taxonomic Sufficiency (BITS) was
specifically developed for lagoonal systems, according to the tolerant ⁄ opportunistic
approach. Macrobenthic data, variables indicative of eutrophication and
variables indicative of sedimentary organic matter quality were collected during
18 surveys carried out between 2004 and 2005 in three Adriatic coastal lagoons
(Venice Lagoon, Sacca di Goro, Lesina Lagoon). The relationship between environmental
variables and biotic indices (AMBI, BENTIX, BITS, BOPA and
FINE) was tested using multivariate analyses. Indices based on species classification
level appeared to relate better with the variables describing organic matter
quality, whereas BITS, which is based on family classification level, seemed
related to eutrophication indicative variables, such as sulphide, ammonium,
dissolved oxygen and orthophosphate concentrations. The BITS approach
reduces the costs associated with sorting and identification of organisms.
Providing a rapid assessment of ecological quality, and producing an
ecologically relevant classification, BITS seems a promising tool for monitoring
programs of Adriatic lagoonal ecosystems. Its sensitivity in reflecting the field
conditions elsewhere, however, remains to be assessed
Particulate organic matter uptake rates of two benthic filter-feeders (Sabella spallanzanii and Branchiomma luctuosum) candidates for the clarification of aquaculture wastewaters
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