Northeastern Adriatic Research Articles

Scenario-based tsunami hazard assessment for Northeastern Adriatic coasts

Significant tsunamis in the Northern Adriatic are rare, and only a few historical events have been reported in the literature, with sources mostly located along central and southern parts of the Adriatic coasts. Recently, a tsunami alert system has been established for the whole Mediterranean area; however, a detailed description of the potential impact of tsunami waves on coastal areas is still missing for several sites. This study aims to model the hazard associated with possible tsunamis generated by offshore earthquakes, with the purpose of contributing to tsunami risk assessment for selected urban areas along the Northeastern Adriatic coasts. Tsunami modelling is performed by the NAMI DANCE software, which allows accounting for seismic source properties, variable bathymetry, and nonlinear effects in wave propagation. Hazard scenarios at the shoreline are developed for the coastal areas of Northeastern Italy and at selected cities (namely, Trieste, Monfalcone, Lignano and Grado). An extensive set of potential tsunamigenic sources of tectonic origin located in three distance ranges (namely at Adriatic-wide, regional and local scales) are considered for the modelling. Sources are defined according to available literature, which includes catalogues of historical tsunamis and existing active faults databases. Accordingly, a set of tsunami-related parameters and maps are obtained (e.g. maximum run-up, arrival times, synthetic mareograms) that are relevant to planning mitigation actions at the selected sites.

Roman ‘Well-cisterns’, Navigational Routes, and Landscape Modifications in the Venice Lagoon and Northeastern Adriatic

Underwater investigations in the lagoon of Venice have revealed a partially preserved structure interpreted as a Roman ‘well-cistern’. It is indeed very similar to another, better-preserved building excavated in the same area. The analysis of the mortar, the evaluation of the depth of the structure base in relation to relative sea level, and the absence of foundation poles in the underlying soft lagoon mud support such interpretation. A comparison with other poorly-studied Roman buildings of the same type located along the North Adriatic littoral suggests that they were probably used to supply ships with fresh water. In the Middle Ages, similar structures were used in the islands of the lagoon for sustenance of its residents and became a characteristic of the small squares (campi) of Venice.

Microbial response to the presence of invasive ctenophore Mnemiopsis leidyi in the coastal waters of the Northeastern Adriatic

Seasonal blooms of the invasive ctenophore Mnemiopsis leidyi have been recorded throughout the Adriatic Sea, affecting the ecosystem and its pelagic resources. Gelatinous organisms such as M. leidyi release significant quantities of excreta as labile and surface active dissolved organic carbon (DOC) that supports the microbial activity.The effects of M. leidyi's presence on heterotrophic prokaryotes (HP), cyanobacteria (CB) and heterotrophic nanoflagellates (HNF) were investigated at five locations in the coastal waters of Rovinj-Rovigno (northern Adriatic) during intensive blooms in September 2019. Additionally, circulation in the study area was examined using available current measurements and a hydrodynamic model. In September, low-pass filtered currents near the surface were mostly directed toward S-SE reaching 25 cm/s, indicating the presence of the Istrian Coastal Countercurrent (ICCC).Ctenophores displayed a patchy spatial distribution from 0.05 to 100 M. leidyi individuals per m3. When ctenophore density in the swarms surpassed 1 individual per m3, the change in the abundances of microbial groups became evident. The lowest microbial densities and lowest concentrations of dissolved and particulate organic carbon (DOC and POC) and surface-active substances occurred in the absence of M. leidyi, while the highest were within the swarms.We hypothesise that HP utilises the available DOC enhancing the remineralisation of organic matter. Finally, greater availability of HNF's prey (HP and CB) leads to an increase in their abundance.This study illustrates how the release of surface-active DOC during intensive M. leidyi's blooms can stimulate the microbial loop. The current system with the ICCC prevailing in September enables the spreading of M. leidyi from its hypothetic origin in an open sea gyre towards the coast. Bora wind episodes may initiate and favour this type of circulation. In these conditions, M. leidyi agglomerates in large numbers along the coast, enabling the accumulation of organic matter and altering the abundance of pico- and nanoplankton.

Hail Climatology Along the Northeastern Adriatic

AbstractGeneral awareness and overall interest regarding hailstorms and hail properties in Europe have increased significantly in the last several decades and have resulted in numerous local, national, and even Europe‐wide studies on hail and hail properties. To contribute to this field, we determined the hail climatology in the northeastern (NE) Adriatic region and analyzed its spatial and temporal patterns and performed an objectively derived weather type analysis of ERA5 daily mean data and instability indices. We studied the NE Adriatic region due to its focus on agricultural activities and on quality wine production. Our results are based on approximately 60 years of high spatial resolution measurements collected from 27 stations across complex terrain. The results show (i) high levels of spatial variability, (ii) significant annual variations, and (iii) hail throughout the whole year that (iv) intensifies in summer months. Furthermore, redistribution of hail among seasons (in particular, from summer to spring) was detected. Most significant changes were visible in the June–October period, with a negative trend of −0.06 hail days/year, and the period from November to March exhibited a positive trend of 0.13 hail cases/year. We found that deep cyclonic systems in front of and above our domain were most responsible for hail generation, often supported by southwesterly winds. Additionally, the vast majority of observed hail events occurred in unstable and sheared environments.

Revisiting Vertical Land Motion and Sea Level Trends in the Northeastern Adriatic Sea Using Satellite Altimetry and Tide Gauge Data

We propose a revisited approach to estimating sea level change trends based on the integration of two measuring systems: satellite altimetry and tide gauge (TG) time series of absolute and relative sea level height. Quantitative information on vertical crustal motion trends at six TG stations of the Adriatic Sea are derived by solving a constrained linear inverse problem. The results are verified against Global Positioning System (GPS) estimates at some locations. Constraints on the linear problem are represented by estimates of relative vertical land motion between TG couples. The solution of the linear inverse problem is valid as long as the same rates of absolute sea level rise are observed at the TG stations used to constrain the system. This requirement limits the applicability of the method with variable absolute sea level trends. The novelty of this study is that we tried to overcome such limitations, subtracting the absolute sea level change estimates observed by the altimeter from all relevant time series, but retaining the original short-term variability and associated errors. The vertical land motion (VLM) solution is compared to GPS estimates at three of the six TGs. The results show that there is reasonable agreement between the VLM rates derived from altimetry and TGs, and from GPS, considering the different periods used for the processing of VLM estimates from GPS. The solution found for the VLM rates is optimal in the least square sense, and no longer depends on the altimetric absolute sea level trend at the TGs. Values for the six TGs’ location in the Adriatic Sea during the period 1993–2018 vary from −1.41 ± 0.47 mm y−1 (National Research Council offshore oceanographic tower in Venice) to 0.93 ± 0.37 mm y−1 (Rovinj), while GPS solutions range from −1.59 ± 0.65 (Venice) to 0.10 ± 0.64 (Split) mm y−1. The absolute sea level rise, calculated as the sum of relative sea level change rate at the TGs and the VLM values estimated in this study, has a mean of 2.43 mm y−1 in the period 1974–2018 across the six TGs, a mean standard error of 0.80 mm y−1, and a sample dispersion of 0.18 mm y−1.

Fish Canning Industry and The Rhythm of Social Life in the Northeastern Adriatic

The article discusses the social world formed around canneries in small coastal and insular towns in the northeastern Adriatic. Although associated with hard, unpleasant labor and demanding work conditions, the fish canning industry, particularly in the period of late socialism, offered a framework in which a meaningful social life was organized and lived. In this way, the local impact of canneries reached much beyond providing financial means to its employees. To understand the social meaning of fish canning in the Yugoslav Adriatic, the article focuses on the relationship between the now largely vanished local fish canning industry and tourism that is increasingly becoming the dominant (and the only) source of income for local communities. Lefebvre’s concept of rhythmanalysis proves to be a productive lens to view the complex and often ambiguous relationship between the two industries, and to narrate the history of fish canning through the senses – what was seen, heard, smelled, felt. These intense, embodied, sensorial memories caution us that the dominant claims and narratives which interpret the replacement of industry with tourism (and other tertiary sector activities) as a necessary, inevitable and desirable developmental step should not be taken for granted.

Multidisciplinary insight into late Roman rural settlement on the northeastern Adriatic coast of Croatia: Island of Rab case study

Results of multidisciplinary research conducted on the island of Rab (Northeastern Adriatic, Croatia) are presented with particular focus on late Roman rural settlements and their economic activities. The settlement in Podšilo bay, Lopar peninsula, is analyzed in more detail, providing evidence on a vibrant local community engaged in diversified craft activities and the exploitation of local land and marine resources. Along with the specificities of its layout and organization, this site also presents unique possibilities to study environmental factors that influenced its setup and economy, but also its demise, tentatively placed within the 6th century AD.

Relative sea-level change and climate change in the Northeastern Adriatic during the last 1.5 ka (Istria, Croatia)

A new high-resolution relative sea-level (RSL) reconstruction is presented for the past 1500 years based on four bio-constructions formed by alga Lithophyllum byssoides (algal rims). Two algal structures have been studied on the southern (Premantura site) and two on the eastern Istrian coast (Uboka and Brseč sites) in the Northeastern Adriatic. The data from the algal rims (47 radiocarbon data points) enabled the distinction of four major phases of RSL change which corresponds to periods of climate change. RSL between AD 400 and 800 during the Dark Ages Cold Period (DACP), was almost stable. After AD 800, during the Medieval Climate Anomaly (MCA) the RSL increased up to ∼0.8 mm/yr. The following Little Ice Age period, (LIA) interval I (AD 1400 till 1600) is again characterised by RSL stability (RSL slowed down) which allows the rims at the southern coast to reach the width of ∼40–80 cm at their uppermost part and up to 20 cm for those along the eastern coast. Between AD ∼1600 and 1750, during the colder LIA II interval, algal rims do not form, as LIA II is assumed to be a period of RSL fall. Algal rims reveal that from the second part of the 19th century the RSL rose by 13–15 cm at the Premantura location and around 10 cm at the Brseč and Uboka areas, providing rates between 1 and 0.7 mm/yr respectively for the Current Warm Period (CWP).The sea-level trends were quantitatively defined using an Errors-In-Variables Integrated Gaussian Process (EIV-IGP) model, with full consideration of the available uncertainty. Following correction for the total land-level change (assumed to be around −0.4 mm/yr), four successive trends in sea-level change were confirmed. Sea-level dropped during the DACP at a mean rate of −0.4 mm/yr and increased to 0.5 mm/y as a consequence of Medieval warmth. Thereafter it was relatively stable during LIA I, fell up to −0.1 mm/yr during LIA II interval and has been slowly rising again during the CWP. Moreover, L. byssoides δ18O records show that these periods of sea-level changes are consistent with changes in temperature and thus with periods of rapid climate change.

First report on abundance and distribution of common bottlenose dolphins (Tursiops truncatus) in the NATURA 2000 area, Istria, North-eastern Adriatic Sea

The bottlenose dolphin (Tursiops truncatus M.) local population off west Istria in the North-eastern Adriatic has received no prior study of abundance and distribution despite the habitat's relevance for the preservation of this key species in the marine ecosystem. The research area comprises part of the NATURA 2000 network which was predominantly established here for these dolphins. Official data regarding the local population's status in the region are currently marked as deficient. Thus, the aim of the present study was to provide the first population data for the area. Boat-based survey work was carried out from April to September 2012–2015 using a mark–recapture photo-identification method. Prior to this period a random data collection was used to study distribution, since 2001, to cover the area of 927 km2 lying between Umag to lighthouse Albanež in the south. 143 bottlenose dolphins were photo-identified to date with the average group size of 9.27 ± 6.53 animals. Several abundance models were used, from which the Markovian robust model proved the best fit and predicted between 47–142 dolphins along the west Istria coast. A few individuals were also identified in Slovenia, indicating a bigger home range along the 98 km length of the studied area. There is an indication of a regular year round presence of dolphins. The west Istria coast constitutes an important feeding and breeding ground. The region should develop a sustainable plan to manage those human activities negatively impacting the dolphins. Therefore the present study is of relevance for the implementation of management directives for their conservation.

Interaction of Sea Breeze and Deep Convection over the Northeastern Adriatic Coast: An Analysis of Sensitivity Experiments Using a High-Resolution Mesoscale Model

This study investigates the sensitivity of a high-resolution mesoscale atmospheric model in the model reproduction of thermally induced local wind (i.e., sea breezes, SB) on the development of deep convection (Cb). The three chosen cases are simulated by the Weather and Research Forecasting (WRF-ARW) model at three (nested) model domains, whereas the area of the interest is Istria (peninsula in the northeastern Adriatic). The sensitivity tests are accomplished by modifying (1) the model setup, (2) the model topography and (3) the sea surface temperature (SST) distribution. The first set of simulations (over the three 1.5-day periods during summer) is conducted by modifying the model setup, i.e., microphysics and the boundary layer parameterizations. The same events are simulated with the modified topography where the mountain heights in Istria are reduced to 30% of their initial height. The SST distribution has two representations in the model: a constant SST field from the ECMWF skin temperature analysis and a varying SST field, which is provided by hourly geostationary satellite data. A comprehensive set of numerical experiments is statistically analyzed through several different approaches (i.e., the standard statistical measures, the spectral method and the image moment analysis). The overall model evaluation of each model setup revealed certain advantages of one model setup over the others. The numerical tests with the modified topography showed the influence of reducing the mountains heights on the pre-thunderstorm characteristics due to: (1) decrease of sensible heat flux and mid-tropospheric moisture and (2) change of slope-SB wind system. They consequently affect the evolution and dimensions of SBs and the features of the thunderstorm itself: timing, location and intensity (weaker storm). The implementation of the varying SST field in the model have an impact on the characteristics and dynamics of the SB and finally on the accuracy of Cb evolution, duration and the intensity. SST variations emphasized the importance of the phase matching in both daytime cycles of SB and Cb due to their extremely strong nonlinear relationship.

Modelling the formation of dense water in the northern Adriatic: Sensitivity studies

This study aims to document the effects of imposing different river runoff forcing and tidal forcing to the dense water formation (DWF) rates and dynamics in a semi-enclosed sea. An extreme DWF episode that occurred in the winter of 2012 in the shallow northern Adriatic Sea during a prolonged cold bora wind outbreak event has been reproduced using a one-way coupled atmosphere-ocean modelling system comprised of the atmospheric Aladin/HR mesoscale model and ocean ROMS model. Three different river runoff forcing and tides/no tides scenarios were imposed on the model. The introduction of tides and river climatology instead of real rivers did not substantially change the modelled DWF transports and volumes, whereas the simulation using the old Raicich climatology resulted in a substantial freshening of the entire Adriatic that reduced or prevented the DWF at sites in the northern and northeastern Adriatic. The necessity of using an up-to-date river runoff climatology to properly reproduce the DWF in semi-enclosed seas is emphasised.

Assessment of pollution level using Mytilus galloprovincialis as a bioindicator species: The case of the Gulf of Trieste

A multidisciplinary approach was used to estimate the pollution level of the marine environment in the North Eastern Adriatic by measurement of the isotopic composition of carbon and nitrogen (δ13C, δ15N), metal/metalloids analyses (Fe, Cu, Zn, As, Se, Cd and Pb, including As speciation) in the Mytilus galloprovincialis, as well by using metallothioneins (MT) concentrations, micronuclei (MN) in gill cells and biological parameters (condition index and gonadosomatic index). Concentrations of MT were in the range from 44 to 175μgg−1 wet matter tissue and were higher at the end of the winter season. The frequency of MN did not indicate an elevated level. Sewage sludge pollution was not confirmed. Elevated As concentrations in mussel are related to salinity and low nutrients concentrations and not to pollution. Elevated concentrations of Cu, Zn and Pb were found in the Bay of Koper in comparison with the Bays of Strunjan and Piran.

Wind patterns associated with the development of daytime thunderstorms over Istria

Abstract. The northeastern (NE) Adriatic in the northern Mediterranean is the area with (i) the highest frequency of thunderstorms in Croatia, and (ii) frequent appearances of sea breeze (SB) along the coast. This study investigates the impact of the combined large-scale wind (associated with particular synoptic conditions) and the SB on the moist convection development over the NE Adriatic. The four selected cases were (i) chosen on the basis of a daytime moist convection; (ii) supplemented by one of the dominant large-scale winds with seaward (NE, NW) and landward (SW, SE) directions and (iii) simulated by WRF numerical model. The near-surface wind patterns consisted of SBs along the coastline, generated a narrow eastward-moving convergence zone (CZ) along the area if the large-scale wind was less than 9 m s−1 (below 500 hPa). Apart from the low-level CZ, the advection of large-scale wind influenced the lifetime and movement of the initial Cb cells. While the local front collision with the NE wind advection caused the thunderstorm to propagate southward, the CZ and fronts interaction determined the afternoon northwestward storm movement against the NW large-scale wind. Due to particular synoptic background, the thunderstorm event in SE case was the shortest with only a minor impact on the SB. While the origins and locations of storm cells were completely controlled by the low-level CZ and the upward advection of low-level moisture at the SB front, the most typical convective case with SW warm-wet wind only partially supported the SB–Cb interaction.

Surface transport in the Northeastern Adriatic Sea from FSLE analysis of HF radar measurements

This study focuses on the surface transport in the Northeastern Adriatic Sea and the related hydrodynamic connectivity with the Gulf of Trieste (GoT) under calm or typical wind conditions: Bora (from the NE) and Sirocco (from the SE). The surface transport in the area has been investigated by evaluating the Finite-Size Lyapunov Exponents (FSLE) on the current field measured by the High Frequency (HF) coastal radar network. FSLE allow us to estimate Lagrangian Coherent Structures (LCSs), which provide information on the transport patterns associated with the flow and identify regions characterized by different dynamics. This work includes the development and set-up of the FSLE algorithm applied for the first time to the specific Adriatic area considered. The FSLE analysis during calm wind reveals an attractive LCS crossing the GoT entrance, marking the convergence between the Northern Adriatic and the outflowing gulf waters. During Bora episodes this attractive LCS is displaced westward with respect to the calm wind case, indicating that Bora drives an extended coherent outflow from the GoT. On the other hand, Sirocco wind piles up the water along the northern end of the basin. In this area an attractive LCS is found, extending mainly in the SW–NE direction. The sirocco-induced inflow of Adriatic waters in the GoT is mainly driven along its northern (Italian) side, as evidenced by the orientation of the LCS. Under Sirocco condition, as in the Bora case, there is no barrier in front of the gulf. No relevant LCSs are observed in the southern radar coverage area except for Bora cases, when a repulsive LCS develops in front of the Istrian coast separating water masses to the North and the South of it.

Wind Regimes Associated with a Mountain Gap at the Northeastern Adriatic Coast

AbstractWinds through the Vratnik Pass, a mountain gap in the Dinaric Alps, Croatia, are polarized along the gap axis that extends in the northeast–southwest direction. Although stronger northeasterly wind at the Vratnik Pass is frequently related to the Adriatic bora wind, especially at the downstream town of Senj, there are many cases in which the wind at Senj is directionally decoupled from the wind at the Vratnik Pass. A cluster analysis reveals that this decoupling is sometimes related to lower wind speeds or a shallow southeasterly sirocco wind along the Adriatic, but in many cases the bora blows over a wider region, while only Senj has a different wind direction. Several mechanisms can be responsible for the latter phenomenon, including the formation of a lee wave rotor. A numerical model simulation corroborates the decoupling caused by a rotor for a single case. The prevalence of northeasterly winds at the Vratnik Pass during southeasterly sirocco episodes is another result that challenges the current understanding. It is shown that, at least in one of these episodes, this phenomenon is related to a secondary mesoscale low pressure center in the eastern lee of the Apennines that forms as a subsystem of a broader Genoa cyclone. Less frequent southwesterly winds through the gap are predominantly related to the thermal sea breeze and anabatic circulations that are sometimes superimposed on the geostrophic wind.

Seismogenic sources in the Adriatic Domain

We present an overview of the seismogenic source model of the Adriatic domain included in the latest version of the DISS database (http://diss.rm.ingv.it/diss/) and in the European SHARE database (http://diss.rm.ingv.it/SHARE/). The model consists of Composite and Individual Seismogenic Sources located inside and along the margins of the Adria plate. In order to locate and parameterize the sources, we integrated a wide set of geological, geophysical, seismological and geodynamic data, either available from published literature or resulting from our own field work, seismic profile interpretations and numerical modelling studies. We grouped the sources into five regions based on geometrical and kinematic homogeneity criteria. Seismogenic sources of the Central Western Adriatic, North-Eastern Adriatic, Eastern Adriatic and Central Adriatic regions belong to the Northern Apennines, External Dinarides and offshore domains, respectively. They are characterized by NW–SE strike, reverse to oblique kinematics and shallow crustal seismogenic depth. Seismogenic sources of the Southern Western Adriatic region instead are E–W striking, dextral strike-slip faults, cutting both the upper and lower crust. The fastest moving seismogenic sources are the most southern thrusts of the Eastern Adriatic and the strike-slip sources of the Southern Western Adriatic, while the seismogenic sources of the Central Adriatic exhibit the lowest slip rates. Estimates of maximum magnitude are generally in good agreement with the historical and instrumental earthquake records, except for the North-Eastern Adriatic region, where seismogenic sources exhibit a potential for large earthquakes even though no strong events have been reported or registered. All sources included in the database are fully geometrically and kinematically parameterized and can be incorportaed in seismic hazard calculations and earthquake or tsunami scenario simulations.

Marked reduction of eutrophication pressure in the northeastern Adriatic in the period 2000–2009

Parameters relevant to the study of eutrophication processes in the northeastern Adriatic (NEA) during the period 2000–2009 were analysed and compared with a previous period (1972–1999). The data used in this study were collected at two stations in the coastal zone up to 13 NM off Rovinj (western Istria). The more recent period was characterised by a strong reduction of the Po River flow rate and different circulation regime with the more frequent inflow of high salinity and oligotrophic water from the central Adriatic. Change in the circulation was evidenced by lower frequencies of the Istrian Coastal Countercurrent (ICCC) as compared to the Eastern Adriatic Current (EAC) after 2000, particularly in spring. As a consequence, a marked increase in surface salinity and decrease in orthophosphate and chlorophyll a concentrations at two stations in the period 2000–2009 occurred. In contrast, during late winter and in spring of the more recent period, dissolved inorganic nitrogen (DIN) concentrations were higher, despite the lower freshwater discharge and increased inflows on nutrient-poorer water. This DIN increase was very probably due to an enhanced reduction of orthophosphate concentration after 2000, limiting further the phytoplankton growth, resulting in a more marked accumulation of unused DIN. The obtained results showed that the eutrophication pressure was markedly reduced in the NEA during 2000–2009 in respect to the previous period.

The Influence of Geological Hazard on Turistic Development in the Kvarner Area (Northeastern Adriatic Sea)

This paper will analyze the influence of natural hazard on the vulnerability of the area and assess the degree of potential risk in Kvarner as an important tourist region of Croatia. Liburnia and Vindol coast and the northern part of the island Krk are located in a seismically active area, where earthquakes have already occurred, so it can be expected they will repeat, although one can not predict when, where and with which intensity. Reducing risk from earthquake effects to an acceptable level can be successfully implemented by appropriate technical measures. Special attention should be paid to the phenomena of different types of hazards caused by climate change, which is already happening, and their acceleration on Kvarner region is assumed. Raising and increased vigor and frequency of storms are expected as primary effects of climate change. These phenomena may occur independently or jointly. This paper will evaluate the primary, secondary and tertiary effects of different types of natural hazards such are the destruction of beaches, flooding of the coast, etc. The degree of vulnerability of the coastal area of Kvarner area with highest tourist capacity will be assessed as well as the degree of risk that can be caused by these phenomena. Assessment of natural hazard and its management is a general and actual society need, particularly expressed in vulnerable areas such is the area of Kvarner. Current approach to the management of geological hazard in the area of Republic of Croatia is extremely fragmented and inefficient. Therefore, governing bodies are in dispose of unreliable basis for the management of space in terms of sustainable development.

Factors Triggering Sea Cliff Instability Along the Slovenian Coasts

FURLANI, S., DEVOTO, S., BIOLCHI, S and CUCCHI, F., 2011. Factors Triggering Sea Cliff Instability Along the Slovenian Coasts. In: Micallef, A. (ed.), MCRR3-2010 Conference Proceedings, Journal of Coastal Research, Special Issue, No. 61, pp. 387–393. Grosseto, Tuscany, Italy, ISSN 0749-0208.The cliff retreat is the sum of the sustained action of marine and continental factors. Their interrelations depend on the geological and environmental settings of the area. The studied cliffs are cut in the Eocene Flysch, a turbiditic succession composed by centimetric—metric sandstones with millimetric-centimetric interbedded silty marlstones, almost horizontal in the study area. The low resistance of the rock mass allows the rapid retreat of the cliffs and the development of wide shore platforms.This work aims at evaluating sea cliff retreat and the factors that trigger the collapse of material and its removal from the cliff foot. Different methods have been used: a detailed characterization of the geomechanical properties and the quality of rock masses, the susceptibility to rock falls and a photographic surveying.The sea cliff retreat in five sites along the Slovenian coast, in the Northeastern Adriatic Sea, has been studied through the comparison of more than 7000 pictures collected since 1998, at precise time steps and under any weather conditions. These data have been subsequently compared with archaeological data, historical maps and the characterization of the geomechanical features of rock masses in order to determine the factors triggering the cliff retreat. Photographic surveying displays a rapid but complex behaviour of the cliff retreat: during long stable-weather periods, cliff modifications are very low and groundwater solution or landslides have been observed. Major changes in the cliff face have been observed after great storm events, because of a complex interaction between marine and non-marine factors.The integrated method proposed here, including the photographic surveying and the geomorphological-geomechanical characterisation of rock masses is a valuable method for understanding and evaluating the mechanisms of cliff retreat.

Ecotoxicological evaluation of Harbour sediments using marine organisms from different trophic levels

Background, Aim and Scope The toxicity of contaminated sediments should be evaluated considering the direct exposure of laboratory organisms to whole sediments and the indirect exposure to elutriates or extracts (Tay et al. 1992, Byrne and Halloran 1999, Nendza 2002). The alga Dunaliella tertiolecta is indicated for the use in toxicity bioassays because it is highly sensitive to several xenobiotics. Harpacticoid copepods have been already used for toxicity testing and Tigriopus fulvus is a promising Mediterranean target-species in ecotoxicology (Todaro et al. 2001, Faraponova et al. 2003, Pane et al. 2005a). In this study, the toxicity of sediments collected in harbour sites of the Northeastern Adriatic Sea was evaluated by growth inhibition test with free living and alginate-immobilized Dunaliella tertiolecta and acute toxicity test with nauplii and adult Tigriopus fulvus with the aim of pointing out the importance to utilize model organisms from different trophic levels in sediment ecotoxicology.