Ficopomatus'Reefs' in the Po River Delta (Northern Adriatic): Their Constructional Dynamics, Biology, and Influences on the Brackish-water Biota     

Carlo Nike  Bianchi Carla  Morri 《Marine Ecology》1996,17(1-3):51-66

Abstract. The serpulid polychaete Ficopomatus enigmaticus (F auvel , 1923) builds huge aggregates in the "Sacca del Canarin", a brackish inlet of the Po River Delta (Italy). Distribution, structure and development of these 'reefs'. together with their associated biota, were studied by field observations and settlement panels from 1977 to 1979. Some aspects of the serpulid biology (settlement periods, tube growth, life strategy) were also taken into account. Ficopomatus reefs influence in many ways the brackish-water ecosystem: they form the main hard substrate; are major sediment source; help in regulating the trophic status of the lagoon; and act as refuge for many invertebrate species.  相似文献   

Meiofauna and macrofauna community structure in relation to sediment composition at the Iberian margin compared to the Goban Spur (NE Atlantic)     

Els Flach  Agnes Muthumbi  Carlo Heip 《Progress in Oceanography》2002,52(2-4)

Meiofauna and macrofauna communities and several sediment characteristics were compared between a slope situated far from the coast (Goban Spur) and two transects across the Iberian Margin with steep slopes and close to the shore. The northern Galician transect (off La Coruña) was situated in an area subjected to wind-induced upwelling events. The western Galician transect was also subjected to upwelling, was additionally influenced by outflows of water rich in organic matter from the Rías Bajas. This transect also included the Galicia Bank. Macrofauna density decreased exponentially from the shelf edge (154 m) to the abyssal plain (4951 m) and different communities occurred on the shelf, the upper- and lower slope and on the abyssal plain. Apart from two extremely low-density stations on the Iberian Margin, there were no significant differences in the meiofauna between the Goban Spur and the Iberian Margin. Along the La Coruña-transect a station where meiofaunal densities were low occurred at a depth of 1522 m, where the sediment was characterised by having a high median-grain size, ripple structures, a low C_org and total N content. There were relatively high numbers of macrofaunal filter-feeders but low numbers of crustaceans, indicating a high current velocity regime. On top of the Galicia Bank (˜770 m) the sediment consisted mainly of shells of pelagic foraminifers, and had low contents of C_org and N. The macrofauna was dominated by filter-feeding and carnivorous taxa. At both these stations meiofauna densities were low. Meiofauna densities and community structure differed between the Goban Spur and the Iberian Margin. Meiofauna densities on the Galician shelf were more than double those on the Goban Spur shelf. The two deep stations on the La Coruña transect and the deepest station on the Galicia Bank transect all contained meiofaunal densities that were higher than found at similar depths off the Goban Spur. The meiofaunal densities were inversely correlated with %CaCO₃ content and, excluding the shelf stations, were positively correlated with both %C_org and total N at the Iberian Margin. Neither upwelling nor the enriched outflows from the rias affected the macrofauna, but meiofaunal densities were greatly enhanced.  相似文献   

The economic sustainability of artisanal fisheries: the case of the trawl ban in the Gulf of Castellammare, NW Sicily     

David Whitmarsh  Carlo Pipitone  Fabio Badalamenti  Giovanni D&#x;Anna 《Marine Policy》2003,27(6):489-497

Small-scale fisheries and the communities they support are often given the protection of designated fishing zones from which non-artisanal vessels are excluded. This paper looks at one example of this approach, the trawl ban introduced in the Gulf of Castellammare (NW Sicily), focussing on the economic sustainability of the artisanal fishery currently operating within the protected area. The consequences of lifting the trawl ban and how far this would jeopardise the sustainability of the artisanal fishery are explored via an analysis of the financial viability of trammel net vessels under alternative assumptions concerning catch rates. The paper also investigates fishermen's attitudes towards the trawl ban and their predisposition either to remain in the fishery or to quit in the event of the ban being removed.  相似文献   

Underwater television as a fishery-independent method for stock assessment of Norway lobster (Nephrops norvegicus) in the central Adriatic Sea (Italy)     

Morello  Elisabetta B.; Froglia  Carlo; Atkinson  R. J. A. 《ICES Journal of Marine Science》2007,64(6):1116-1123

  相似文献   

The effect of bedforms (crest and trough systems) on sediment erodibility on a back-barrier tidal flat of the East Frisian Wadden Sea, Germany     

Mahatma Lanuru  Rolf Riethmüller  Carlo van Bernem  Kerstin Heymann 《Estuarine, Coastal and Shelf Science》2007,72(4):603-614

The erosion potential over bedforms in a tidal flat of the East Frisian Wadden Sea was studied by conducting erosion and physical and biological sediment property measurements on the crests and troughs of bedforms. Five stations along a cross-shore transect of 1.5 km length from immediately below the salt marsh to the mid tide-level of the tidal flat were visited during two field campaigns in June and September 2002. Measurements of sediment erodibility were made on both crests and troughs using an EROMES erosion device and quantified in terms of critical erosion shear stress and erosion rate. Surface sediment scrape samples (upper 1 mm layer) were taken from crests and troughs to determine various physical and biological properties of the sediment. The results show that crests are generally more stable (i.e. higher critical erosion shear stresses and lower erosion rates) than troughs. In general, crests contained more chlorophyll a, colloidal carbohydrate, and EPS (extracellular polymeric substance) than troughs. Median grain-size, water content and wet bulk density of the crests showed no statistically significant difference from those of the troughs with the exception at the most landward station immediately below the salt marsh margin, where crests had significantly lower water content and higher wet bulk density than troughs.Two different processes were identified for the difference in erodibility between crests and troughs: (1) At stations with emersion times less than 6 h, the higher benthic diatom biomass (measured as chlorophyll a concentration) on the crests increases the amount of EPS, which is likely to stabilize the sediment surface of these features; (2) in a saltmarsh transition area (most landward station), physical processes such as surface drying and compaction seem to enhance in a synergistic way the sediment stability on the crests.  相似文献   

Palaeoenvironments of early hominins in temperate and Mediterranean Eurasia: new palaeobotanical data from Palaeolithic key-sites and synchronous natural sequences     

Erwan Messager  Vincent Lebreton  Laurent Marquer  Elda Russo-Ermolli  Ronan Orain  Josette Renault-Miskovsky  David Lordkipanidze  Jackie Despriée  Carlo Peretto  Marta Arzarello 《Quaternary Science Reviews》2011,30(11-12):1439-1447

The present study focuses on new palaeobotanical data (pollen, phytoliths and fruits) from three of the oldest Early Palaeolithic sites in Eurasia (Dmanisi in Georgia, Ca’ Belvedere di Monte Poggiolo in Italy and Pont-de-Lavaud in France). The main aim is to examine the ecological factors associated with the first human dispersals out of Africa into Eurasia. The palaeoecological data are discussed with regards to chronology and geographical location of the settlements. The vegetation pattern of each site consists of temperate Eurasian and Mediterranean taxa, subtropical trees being more or less recorded depending on climatic and geographic features. The new palaeobotanical data show that different vegetation structures occurred between the first human dispersal in Caucasus and the later dispersals in western Eurasia. However, in all cases hominins seemed to be adapted to temperate ecosystems. In Caucasus, human occupation took place at 1.7 Ma in a forest-steppe environment, while at ca 1 Ma human populations occupied various settings such as open landscapes or dense forests. These data suggest that during the Early Pleistocene, human populations evolved and dispersed in western Eurasia, gradually increasing their degree of adaptation to diversified environments.  相似文献   

An improved model for the formation times of dark matter haloes     

Carlo Giocoli  Jorge Moreno  Ravi K. Sheth  Giuseppe Tormen 《Monthly notices of the Royal Astronomical Society》2007,376(3):977-983

  相似文献   

Vertical dynamics of disc galaxies in modified Newtonian dynamics     

Carlo Nipoti  Pasquale Londrillo  Hong Sheng Zhao  Luca Ciotti 《Monthly notices of the Royal Astronomical Society》2007,379(2):597-604

We investigate the possibility of discriminating between modified Newtonian dynamics (MOND) and Newtonian gravity with dark matter, by studying the vertical dynamics of disc galaxies. We consider models with the same circular velocity in the equatorial plane (purely baryonic discs in MOND and the same discs in Newtonian gravity embedded in spherical dark matter haloes), and we construct their intrinsic and projected kinematical fields by solving the Jeans equations under the assumption of a two-integral distribution function. We find that the vertical velocity dispersion of deep MOND discs can be much larger than in the equivalent spherical Newtonian models. However, in the more realistic case of high surface density discs, this effect is significantly reduced, casting doubt on the possibility of discriminating between MOND and Newtonian gravity with dark matter by using current observations.  相似文献   

Size matters more than method: Visual quadrats vs photography in measuring human impact on Mediterranean rocky reef communities     

Valeriano Parravicini  Carla Morri  Giada Ciribilli  Monica Montefalcone  Giancarlo Albertelli  Carlo Nike Bianchi 《Estuarine, Coastal and Shelf Science》2009,81(3):359-367

The performances of two commonly used non-destructive sampling procedures for rocky benthic assemblages (i.e. photography and visually assessed quadrats) were compared. A damaging human activity, date mussel (Lithophaga lithophaga) harvesting (DMH), was chosen. Directly impacted sites were compared with reference conditions (controls). Both visual quadrats and photography were equally able to detect differences between impacted situations and controls. However, visual quadrats showed high variability among replicates and estimated higher species richness for controls, while photography did so for impacts. Pooling photos in a ‘sum photo quadrat’ showed that differences between the two methods are due to sampling unit size rather than sampling procedure itself. As a small sampling unit is unavoidable with photography, visual quadrats should be preferred in investigating shallow rocky reefs for their larger size; however, longer working time underwater with quadrats does not allow for numerous replicates. Pooling many photos to reach sampling sizes comparable with those of quadrats may be a valid alternative to reconcile image resolution and areal coverage.  相似文献   

The diurnal cycle of marine cloud feedback in climate models     

Mark J. Webb  Adrian P. Lock  Alejandro Bodas-Salcedo  Sandrine Bony  Jason N. S. Cole  Tsuyoshi Koshiro  Hideaki Kawai  Carlo Lacagnina  Frank M. Selten  Romain Roehrig  Bjorn Stevens 《Climate Dynamics》2015,44(5-6):1419-1436

  相似文献