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

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.     

Urban seagrass: status of Posidonia oceanica facing the Genoa city waterfront (Italy) and implications for management

A system of five adjacent Posidonia oceanica meadows facing the waterfront of Genoa city (Ligurian Sea, NW Mediterranean) was investigated over different spatial scales (meters-kilometers) using three environmental indices: conservation index (CI), substitution index (SI) and phase-shift index (PSI). CI revealed differences mostly at large spatial scale, distinguishing the poor condition of the meadows closest to Genoa centre and harbour from the comparatively healthy condition of the farthest meadows. SI showed differences mostly at small spatial scale (i.e., within meadows), suggesting the influence of local factors in the re-colonisation of regressed meadows by the seagrass Cymodocea nodosa and/or the invasive alga Caulerpa racemosa. Mapping of PSI showed that the meadows closest to Genoa centre and harbour have undergone a nearly total phase shift and have no real potential for recovery: attempts to re-establish P. oceanica there might be a waste of time and money. On the contrary, the meadows farthest from Genoa centre and harbour showed a comparatively low level of phase shift and could still fully recover given specific management actions.     

Classification of natural mineral and spring bottled waters of Portugal using Principal Component Analysis

Considering its area, Portugal is one of the world's richest countries in mineral and spring waters. There are 33 different types of bottled water, 18 of which are classified as natural mineral water and the remaining as spring water. The majority of these waters are of low mineralisation in comparison to most European bottled waters.     

Recent Trends Towards Oligotrophication of the Northern Adriatic: Evidence from Chlorophyll <Emphasis Type="Italic">a</Emphasis> Time Series

The results of the updated and quality-checked data base of field observations on chlorophyll a (Chl a) collected in the period 1970–2007 in the Northern Adriatic Sea are presented. From the last decade, SeaWiFS satellite information was also considered. Results demonstrate a global tendency towards Chl a reduction in the period of investigation, which is more marked in the eutrophic area under the influence of the Po River. In the rest of the basin, which presents meso- or oligotrophic characteristics, long-term changes are more difficult to detect. The long-term field dataset can be divided into two periods: the last decade characterized by the strong decrease observed in the whole northern Adriatic and the earlier period with no or slight increase. The recent substantial reduction of Chl a concentrations is confirmed all over the basin (−0.11 mg m⁻³ year⁻¹) from satellite-derived information. Results are consistent with recently evidenced decrease in concentrations of phosphate and ammonia and point to the existence of oligotrophication in the Northern Adriatic. Results indicate forcefully that the still common perception of the Adriatic Sea as a very eutrophic basin is no longer appropriate, at least for its northern part and in recent years.     

Bacterial biogas production in coastal systems affected by freshwater inputs

The concentrations of two greenhouse gases, nitrous oxide (N₂O) and methane (CH₄), and the bacterial processes involved in their production (nitrification and denitrification for N₂O, and methanogenesis for CH₄), were determined in surface waters of two coastal areas under the influence of freshwater inputs, on one part in the Gulf of Lions and the Rhone River plume, in northwestern Mediterranean Sea, and on the other part in the inner Thermaikos Gulf, in Aegean Sea, eastern Mediterranean Sea. High concentrations of dissolved CH₄ and N₂O were recorded in the surface waters of Gulf of Lions and Gulf of Thermaikos, up to 1300 nM for CH₄, and 40 nM for N₂O. No direct relationship could be found between the concentration and production of the biogases, as they may also be produced in deep water or bottom sediment in shallow areas, or derived from anthropogenic activity or ship contamination in polluted areas. Irrespective of the origin of CH₄ and N₂O, the presence of extremely high concentrations of these two gases in superficial seawater implies that they can easily escape to the atmosphere; consequently, these nearshore waters enriched in greenhouse gases may play an important role in the increase in atmospheric concentration of both CH₄ and N₂O.     

Temporal variability in sources of dissolved organic carbon in the lower Mississippi river

Here we report on the temporal changes in the composition of dissolved organic carbon (DOC) collected in the tidal freshwater region of the lower Mississippi River. Lignin-phenols, bulk stable carbon isotopes, compound-specific isotope analyses (CSIA) and ¹³C nuclear magnetic resonance (NMR) spectrometry were used to examine the composition of high molecular weight dissolved organic matter (HMW DOM) at one station in the lower river over 6 different flow regimes in 1998 and 1999. It was estimated that the annual input of DOC delivered to the Gulf of Mexico from the Mississippi River was of 3.1 × 10⁻³ Pg, which represents 1.2% of the total global input of DOC from rivers to the ocean. Average DOC and HMW DOC were 489 ±163 and 115 ± 47 μM, respectively. ¹³C-NMR spectra revealed considerably more aliphatic structures than aromatic carbons in HMW DOC. Lignin phenols were significantly ¹³C-depleted with respect to bulk HMW DOM indicating that C₄ grass inputs to the HMW DOM were not significant. It is speculated that C₄ organic matter in the river is not being converted (via microbial decay) to HMW DOM as readily as C₃ organic matter is, because of the association of C₄ organic matter with finer sediments. The predominantly aliphatic ¹³C NMR signature of HMW DOM suggests that autochthonous production in the river may be more important as a source of DOC than previously thought. Increases in nutrient loading and decreases in the suspended load (because of dams) in the Mississippi River, as well as other large rivers around the world, has resulted in significant changes in the sources and overall cycling of riverine DOC.     

Macroseismic Parameters of Seismogenic Zones of Calabria and Sicily for Seismic Hazard Evaluation

For the seismic hazard evaluation of the region including the southern Calabro-Peloritanian Arc and southeastern Sicily, the determination of the macroseismic virtual intensity distributions has been carried out, characteristic of the seismogenic zones that fall within the area in study, starting with the structural framework of the region and from the analysis of the observed intensity effected through suitable filters. The macroseismic parameters, derived from such virtual distributions and used for seismic hazard evaluation, are not only a reference for eventual subsequently deeper knowledge referable to the need for a better characterization of the reference modelling, but distinguish themselves as an essential instrument for the definition of seismic hazard scenarios correlated to seismic events that take place in single seismogenic zones.     

Ancient Constructions as Markers of Tectonic Deformation and Strong Seismic Motions

Many ancient structures such as temples were constructed on the basis of a very strict plan and excellent workmanship. For this reason, even their slight deformation due to various effects (ground instability, earthquake oscillations, etc.) can be identified, and it is possible to discriminate between different types of deformation due to earthquakes and those due to other natural causes or to anthropogenic effects. Two study cases are presented here: the Propylaia on the Acropolis and the temple of Hephaistos (Hephaisteion) in the Agora at Athens. In both buildings deformation was produced by earthquakes.