Biogeomorphology of the Mediterranean Posidonia oceanica seagrass meadows

Here we review the multiple interactions between the endemic Mediterranean seagrass, Posidonia oceanica, and coastal geomorphologic processes as an outstanding example of biogeomorphology, taking into account recent advances in the field. Seagrass meadows are among the most important elements for the functioning of marine coastal ecosystems, and represent a major focus for research and conservation. Being considered a priority habitat, P. oceanica meadows are protected by several European Union directives and national laws. In this paper we examine: the role of sedimentary features in controlling the development of the meadows; the interplay between P. oceanica leaf litter (i.e. beached necromass) cast ashore and erosional‐depositional processes on the beaches; the interactions between meadows and nearshore hydrodynamics, and; possible linkages between geomorphological features of the seafloor and the architecture of meadows. Finally, we provide perspectives for future research on P. oceanica and other Mediterranean seagrass meadows in a biogeomorphological context with specific reference to climate change. Copyright © 2016 John Wiley & Sons, Ltd.     

Strike-slip systems as the main tectonic features in the Plio-Quaternary kinematics of the Calabrian Arc

The oblique and diachronous collision of the Apennine-Maghrebian Chain with the Apulian (in the north-east) and Pelagian (in the south) continental forelands, has determined the characteristic arcuate structure of this orogen. The effects of Plio-Pleistocene deformation of the Calabrian Arc have been analysed on the basis of available reflection seismic profiles and using local time-structural maps reconstructed along the main structures. During this period, internal sectors of the Tertiary chain migrated forward on the oceanic Ionian foreland, and were cut by important strike-slip systems. These last have an orientation approximately coincident with that of the migration of the front, allowing differential movement of the different sectors of the arc, towards the weakly buoyant Ionian oceanic domain. The dataset suggests a clear connection between the development of the strike-slip systems cutting the chain and the direction of tectonic transport, towards the East during Late Messinian/Early Pliocene time, to the ESE during Late Pliocene/Early Pleistocene time, finally to the SSE during the Middle/Late Pleistocene to Present, showing a clockwise rotation in well defined stages during the kinematic evolution of the chain. The origin of the Strait of Messina during the different phases is also interpreted in the context of the analysed regional tectonic setting.     

Changes in seabed morphology, mud temperature and free gas venting at the Håkon Mosby mud volcano, offshore northern Norway, over the time period 2003–2006

The Håkon Mosby mud volcano is a 1.5-km-diameter geological structure located on the Southwest Barents Sea slope at a water depth of 1,270 m. High-definition seabed mapping of the mud volcano has been carried out in 2003 and 2006. A comparative analysis of the bathymetry and backscatter maps produced from the two surveys shows subtle morphological changes over the entire crater of the mud volcano, interpreted to be the consequence of mud eruption events. Mud temperature measurements point to a persistently warm mud at shallow depth in the crater. This is explained by upward fluid advection, rather than conductive cooling of mud flows. The small-scale spatial variability in the temperature distribution may be related to mud outflows or changes in the fluid flow regime. Furthermore, the locations of free gas venting observed in 2006 were found to differ from those of 2003. Our observations of overall similar topographic profiles across the mud volcano in 2003 and 2006 suggest that eruption events would have been modest. Nevertheless, the data bring evidence of significant change in activity even over short time intervals of only 3 years. This may be a characteristic shared by other submarine mud volcanoes, notably those considered to be in a quiescent stage.     

Polycyclic aromatic hydrocarbons in water,mussels (Brachidontes sp., Tagelus sp.) and fish (Odontesthes sp.) from Bahía Blanca Estuary,Argentina

Polycyclic aromatic hydrocarbons (PAHs), one of the major groups of anthropogenic environmental pollutants, were firstly identified and measured in coastal waters, native mussels and fish of an industrialized South American estuary.     

Toxicopathic liver lesions in English sole and chemical contaminant exposure in Vancouver Harbour,Canada

The prevalence of toxicopathic liver lesions in English sole (Pleuronectes vetulus) was determined along a presumed gradient of chemical contamination in Vancouver Harbour, Canada. Fish were captured from five sites in or near Vancouver Harbour, British Columbia, Canada. No toxicopathic lesions were observed in fish examined at the reference site (Howe Sound outside Vancouver Harbour), or at the outer harbour site. In contrast, 20-23% of the fish from three sites located in the central harbour, Indian Arm and Port Moody Arm had one or more types of toxicopathic lesions. Likewise, aromatic hydrocarbon (AH) metabolites measured in bile exhibited a gradient in levels from lower concentrations at the reference site to significantly higher levels in fish from Indian Arm and Port Moody Arm harbour sites. The occurrence of toxicopathic liver lesions was statistically associated with concentrations of AHs measured in sediment and AH metabolite levels measured in bile.     

A proposed format for geotechnical data

Large quantities of raw geotechnical data presently exist in the individual collections of institutions and agencies throughout the world. In order to increase the usefulness of this vast amount of data to the scientific community, the National Geophysical Data Center (NGDC) intends to develop a comprehensive data bank for geotechnical information to be located at NGDC, along with a common format for the exchange of geotechnical information. This format would facilitate not only the transfer of geotechnical information between researchers, but also simplify the exchange and development of computer software with which to manipulate the data.     

Zonation and Ecology of Epiphytic Hydroids in a Mediterranean Coastal Lagoon: The 'Stagnone' of Marsala (North-West Sicily)

Abstract. Distribution patterns of epiphytic hydroids of seagrass ( Posidonia occanica and Cymodocea nodosa ) beds were studied in the 'Stagnone', a moderately hypcrhaline lagoon in Sicily. The role of water movement in determining the spatial and temporal zonation of epiphytic hydroids and their morpho-physiological variations is evaluated. Remarks on systematics arc also included.     

Can Rock Composition Affect Sublittoral Epibenthic Communities?

Abstract. Biomineralogy, as the complex of interactions at different levels (cell, organism, species, and community) between organisms and minerals, may play a significant role in the spatial distribution and structure of marine communities. For instance, a negative influence of quartz has been underlined on the Mediterranean benthic communities, which show a species-poorer structure in quartz-rich environments. Excluding the role of quartz, the aim of this work is to verify whether the composition of various mineralogical substrata can affect a hard-bottom benthic community. In the Ligurian Sea, the Levanto area shows an astonishing complex of substrata with different petrographic characters: in a few kilometres, sandstones, serpentinites, gabbros, and basalts occur in geometric association. Consequently, this area represents a suitable frame for this type of study. Herein, algal photophilic assemblages growing on the four mineralogical substrata show significant differences in number of species and percentage cover or abundance. This suggests a significant influence of rock mineral composition on the hard bottom community. Therefore, rock composition must be taken into account for a better understanding of the processes at the basis of hard-bottom community development and diversity.