Exploring Mediterranean and Arctic Environments as a Novel Source of Bacteria Producing Antibacterial Compounds to be Applied in Aquaculture

The need to discover new natural compounds has become urgent as a possible alternative solution to contrast the spread of antibiotic resistance, also in the aquaculture field. Bacterium–bacterium inhibitory activity against bacterial pathogens relevant in aquaculture was evaluated on agar plates for bacteria isolated from cold Arctic (Kongsfjorden, Svalbard Islands; i.e., seawater and sediment samples) and temperate Mediterranean (Lake Faro in Messina and the Straits of Messina, Italy; i.e., brackish water and benthic filter-feeding organisms) environments. Cell-free supernatants (both pure and concentrated 10-fold) were further assayed and, in the case of a positive response, crude extracts were obtained and tested. After the pre-screening procedures, about 30% of the bacterial isolates inhibited the growth of at least one pathogen used as a target. The 10-fold concentrated supernatants of two Arctic Salinibacterium spp. strains and the Mediterranean Bacillus sp. PS62 (associated with the pennatulacean Pteroeides spinosum Ellis, 1764) resulted in being active against P. damselae subsp. piscicida. The crude extracts obtained from Bacillus sp. PS62 also showed inhibitory activity against the same pathogen. Our findings suggest that tested bacteria could represent a novel source of compounds to be applied to overcome pathogenesis in the aquaculture field.

Assessment of the 1783 Scilla landslide–tsunami's effects on the Calabrian and Sicilian coasts through numerical modeling

The 1783 Scilla landslide–tsunami (Calabria, southern Italy) is a well-studied event that caused more than 1500 fatalities on the beaches close to the town. This paper complements a previous work that was based on numerical simulations and was focused on the very local effects of the tsunami in Scilla. In this study we extend the computational domain to cover a wider portion of western Calabria and northeastern Sicily, including the western side of the Straits of Messina. This investigation focuses on Capo Peloro area (the easternmost cape of Sicily), where the highest tsunami effects outside Scilla were reported. Important tsunami observations, such as the wave height reaching 6 m at Torre degli Inglesi and flooding that reached over 600 m inland, have been successfully modeled but only by means of a high-resolution (10 m) topo-bathymetric grid, since coarser grids were inadequate for the purpose. Interestingly, the inundation of the small lake of Pantano Piccolo could not be reproduced by using today's coastal morphology, since a coastal dune now acts as a barrier against tsunamis. Historical analysis suggests that this dune was not in place at the time of the tsunami occurred and that a ground depression extending from the lake to the northern coast is a remnant of an ancient channel that was used as a pathway in Roman times. The removal of such an obstacle and the remodeling of the coeval morphology allows the simulations to reproduce the tsunami penetration up to the lake, thus supporting the hypothesis that the 1783 tsunami entered the lake following the Roman channel track. A further result of this study is that the computed regional tsunami propagation pattern provides a useful hint for assessing tsunami hazards in the Straits of Messina area, which is one of the most exposed areas to tsunami threats in Italy and in the Mediterranean Sea overall.

Routes across Calabria in Antiquity: Locri Epizephiri’s communications over the peninsula and its control of the Tyrrhenian littoral

Locri Epizephiri, a city-state on the Ionian Sea, established settlements on the Tyrrhenian coast and routes across the peninsula of Calabria. Although some scholars have questioned the importance of land routes over the peninsula, this study indicates these itineraries were vital, particularly during the Classical period when Locri came into conflict with Rhegium, master of the Straits of Messina. This study examines Locri’s struggles for supremacy of the Tyrrhenian coast and investigates the major routes in Locri’s territory between the Ionian and Tyrrhenian seas. Much evidence for the itineraries is from the authors’ explorations on the ground in Calabria.

Wind Patterns affect Migration Flyways and Flock Size of a Soaring Bird over Sea

Water surfaces are natural barriers for raptors mostly using soaring–gliding flight over land during migration. Among these, the European Honey Buzzard ( Pernis apivorus) is a total migrant, breeding in Europe and wintering in central western Africa. Each spring thousands of buzzards undertake long sea crossings between Tunisia and southern Italy, concentrating over small islands en route to central eastern Europe. The aim of this research is to investigate the influence of wind patterns on the flyways used by these raptors during this critical phase of migration through field observations at four small Mediterranean islands (Pantelleria, Marettimo, Ustica and Panarea) and at the Straits of Messina between 20 April and 20 May 2006–2013. In our analyses, peak days were considered for each site. This eight year multisite study allowed the collection of a large data set. While crossing the Channel of Sicily, migrants concentrated over Pantelleria (southern side of the Channel) during moderate NW winds, and over Marettimo (northern side) during weaker southerly winds. Over the island of Ustica (north-western Sicily, Tyrrhenian Sea) raptors were observed mostly with weak southerly winds. Over the island of Panarea (northeastern Sicily) and at the Straits of Messina, European Honey Buzzards passed with weak winds from W and NW, respectively. The average flock size during the peak days was significantly higher over the island of Pantelleria, where birds migrated during the stronger winds. The results of this study show that wind patterns affect both migration pathways and flocking behaviour of this species while crossing large water surfaces.

Microbial enzymatic activities and prokaryotic abundance in the upwelling system of the Straits of Messina (Sicily): distribution, dynamics and biogeochemical considerations

Three microbial enzymatic activities involved in organic matter transformation (Leucine AminoPeptidase, LAP, β-glucosidase, β-GLU and Alkaline Phosphatase, AP) and prokaryotic abundance were studied in the Straits of Messina upwelling system. Samplings were performed monthly, between June 2003 and March 2004, at three stations with different hydrodynamic patterns. Potential hydrolysis rates were estimated using specific fluorogenic substrates. Unlike total prokaryotic abundances, quite spatially homogeneous, enzymatic values described different scenarios for each examined station. At the southern Sicilian side (Scaletta) the highest average activity rates were recorded (LAP: 72.19 ± 19.14 nmol C_leu dm⁻³h⁻¹, β-GLU, 12.53 ± 3.15 nmol C_glu dm⁻³h⁻¹, AP, 113.59 ± 35.47 nmol PO₄dm⁻³h⁻¹), while at the Calabrian side (Pellaro) the minimum values of LAP, β-GLU and AP were measured. Enzymatic activity values showed seasonal patterns everywhere, with summer values which were one order of magnitude higher than those recorded in other seasons and autumn values which sharply decreased. During winter, the enhanced rates of β-GLU and AP suggested the occurrence of active polysaccharide decomposition and phosphorus regeneration. The variability in the enzymatic activity patterns recorded in the Straits area was indicative of biogeochemical features differing among the examined stations; this resulted in changes in the balance between production and decomposition processes.