Time and place

10:00-10:08 Roy Jaijel - Geoarcheological work in Vista Alegre - A maritime Maya site

10:10-10:18 Nadine Hoffmann - Palaeotsunami & Natural Hazards

10:20-10:28 Joel Roskin - Beach buildup and coastal aeolian sand incursions off of the Nile littoral cell during the Holocene

Israel's coastal plain is abundant with sand which originates from the Nile littoral cell. The sand is transported along the southeastern Mediterranean Sea through wind and wave induced currents and its fluxes are understood to have been generally constant since at least the middle Holocene. Once reaching the shores, the sand is windblown inland and has formed 3-6 km wide lobe-like sand and dunefields that are currently stabilized by vegetation. Dunefield morphologies include foredunes, loose aeolian sand sheets, and linear, transverse and parabolic dunes.

This study reviews the architecture, geo-archaeology and chronologies of the aeolian morphologies of the dunefields along the Mediterranean coast of Israel in order to: (a) Date the timings of sand and dune incursions (b) Identify the transitions between different and changing drivers of sand incursion and dune growth with time and along different segments of the coast (c) Discriminate between climatic, environmental, historic and modern human-induced forcing factors of sand mobilization and stabilization (d) Present a conceptual and physical model of the incursion stages (e) Assess scenarios of sand mobilization/stabilization in the future.

Inquiry of the beach buildup and sand and dune incursion and growth chronology is achieved through a combination of luminescence ages, radiocarbon dates and relative ages from previously published geological and archaeological papers and reports, historical texts, together with new optically stimulated luminescence (OSL) ages combined with stratigraphic and sedimentological data. The chronologies are analyzed with respect to marine and coastal processes, aeolian geomorphology, climate and connections to human occupations.

Three main stages and controlling forms of sand and dune mobilization are identified: (1) environmentally driven (2) controlled by historic land-use intensity and (3) mainly stabilization by modern land-use/negligence practices. At 6-5 ka, the rapid rates of sea level rise declined and beach sand buildup took place. Where aeolianite ridges bordered the coast, pulses of aeolian sand sheets that included biogenic carbonate grains unconformably draped the ridges and rapidly consolidated into a distinct sandy calcarenite unit. This unit, known as kurkar Tel-Aviv extends several of hundred meters from the palaeo-coast line. Further east, sand sheets partly pedogenized following their incursion, but did not cement. The commencement of this middle Holocene sand incursion followed a short gap in inland aeolian sand sheet sedimentation that intermittently continued from 40 ka to 12-8 ka along the central and southern coast to form the Pleistocene (Netanya) hamra (Rhodoxeralf) coastal soil unit.

Until Middle Bronze times, sporadic sand veneers further penetrated inland and generally eastwards from the beach for several kilometers. The water retention capacities of the sand sheets enabled the establishment of a vegetation cover that probably became an attractive environment for fuel and grazing. This environment may have attracted the invading Philistines around 3.5 ka by Gaza, Ashkelon and Ashdod. The growing population occupations since Hellenistic fortification of the coast, expanding into Roman and Byzantine times, probably led to increased consumption and massive destruction of sand stabilizing vegetation. These activities enabled sand erodibility and mobilization during storms. The sand sheets gradually expanded to the current limits of today's dunefields. The incursion extent was generally constrained by existing wadis and streams, many that run parallel to aeolianite ridge orientations. The sand incursions initiating from the beach, depleted and thus limited sand accretion upon the beach. In general, dune and sand sheet sedimentologies imitate those of the source beach sand to its west.

The uneven, substantial and gradual demographic drop during post-Byzantine times enabled reestablishment of natural vegetation and rapid regosol development upon the central coastal sands. This landscape response occurred differentially along the coast in response to local demographics and human land-use practices. Around the metropolis of Caesarea, intensive Roman-Byzantine land use dropped drastically by 1.1 ka while in the southern coast, only following the Crusader abandonment around 0.7 ka, did the sand vegetation rehabilitate. The stabilization lag in the southern sands may be partly attributed to its lower capacity for vegetation growth due to a thicker profile and deeper water infiltration, higher sand supply and less precipitation than in the central coast. For example, based on modern observations, the Nizzana sands reveal a 70% potential for vegetation cover by Saharo-Arabian associations that slowly stabilize the sand allowing for a longer transition period of dune bi-stability, while by Caesarea, the Mediterranean vegetation more rapidly attains a ~100% cover.

We suggest that the 19-20th century dune construction evolved directly from the existing sand sheet that intermittently developed and accumulated since 6-5 ka. Human destruction of vegetation, attributed to the accelerating population growth along the coast that included Bedouins and establishment of villages settled by populations of various ethnic backgrounds made the sand prone to "in situ" transverse dune formation in response to powerful winds. Increased late 19th century storminess probably allowed for abundant wind power enabling sand mobilization. The dunes encroached several hundreds of meters inland. In western parts of the dunefields, the dune mobilization partly scalped the sand deposits near the coast leading to sand supply starvation. This process was enhanced especially following the British establishment of stabilizing and vegetated foredunes along the coast in the mid-20th century obstructing inland sand input from the beach.

To summarize, the study presents the conditions in archaeological and historical coastal aeolian landscapes where marine sand supply is understood to be generally constant since sea level stabilization and the range and resolution of climate changes are usually insignificant with regard to sand mobilization. Human-nature interactions gradually and intermittently become superior over natural processes and illustrate how traditional and modern land practices generate contrasting environmental impacts upon unconsolidated and vegetated sand bodies.

Roskin, J., Bookman, R., Ackermann, O, Porat, N., Sivan, D.

10:30-10:38 Shahrazad Trbous Sirhan - Methane bubble dynamics within muddy aquatic sediments under different ambient methane concentration profiles

Methane (CH₄) is the simplest and, the most common hydrocarbon in nature. It is considered as one of the most adverse greenhouse gases, at least 25 times more potent than carbon dioxide. When concentration of the dissolved methane in pore waters exceeds the solubility of the gas (affected in turn by temperature, pressure, salinity and by other factors) methane bubbles nucleate. Gas migration in fine-grained cohesive muddy aquatic sediments is accompanied by sediment fracturing. When gas pressure is high enough to overcome compression, friction, and cohesion at grain contacts, gas migrates by pushing the grains apart. These sub-vertical fractures provide lowered-resistance conduits for migration of other bubbles that can destabilize sediment structure resulting even in slope failure. Therefore, understanding the processes governing bubble propagation within fine-grained aquatic sediment is important. Previous models showed that bubbles propagation within fine-grained muddy aquatic sediments can be modeled using principles of linear elastic fracture mechanics. Mass transfer between the bubble rising with high velocity and the surrounding sediments was mostly ignored. In this study we use coupled macroscopic mechanical/reaction-transport numerical model to characterize bubble ascent under the constant and the variable (subsiding upward) dissolved methane concentration profiles (Fig. 1). It is demonstrated that bubble ascent pattern is characterized by two sequential propagation scenarios:  (1) Stable fracturing, followed by (2) Dynamic (unstable) fracturing (Fig. 2). Under the variable vertical profile of concentrations, associated with bio-chemical process of methane consumption within the sediment, bubble ascent is slower (Fig. 3).  Based on propagation time scale on both cases, it is anticipated that the bubble will stop once the negative total diffusive flux over its surface will manage to set the fracturing back to the stable regime.

Fig. 1  Initial settings for modeling of the bubble upward propagation under two different ambient dissolved-methane concentration  profiles. Panel (a) presents initial opening of the modeled mature bubble. Panel (b) presents two different profiles of the dissolved-methane concertation: constant concentration (blue line), and spatially variable concentration (orange line).

Fig. 2 Stress Intensity Factor (SIF) at a bubble head as function of time, showing two sequential propagation patterns:  (1) Stable propagation and (2) Dynamic propagation. Panel (a) presents the SIF at bubble’s head under constant concentration profile, the dynamic fracturing starts at t~15 (s). Panel (b) presents the SIF at bubble’s head under variable concentration profile, the dynamic fracturing starts at t~30 (s). 

Fig. 3 Plots (a) and (b) present the local diffusive methane fluxes (kg/m^2  ∙ s) through the bubbles' surfaces (1/2 of each surface is depicted) at t=17(s) after the beginning of their upward migration, under the different concentrations: a) under the constant concentration profile, b) under the subsiding upward concentration profile). Under the constant concentration profile the bubble propagated a larger distance than the bubble under the varying concentration (ignoring bubble closed part). Colors indicate diffusive methane fluxes over the bubbles' surfaces. Zero diffusive flux (dark blue color) is observed at the closed part of the bubble tail. c) and d) present bubble opening and propagation distance after 17(s) under, respectively,  the constant  and variable concentration profiles.

Sirhan S., Katsman R., Ten Brink U. 

10:40-10:48 Dr. Uri Schattner - Levant Jet System - a sediment conveyor

Sedimentary development of a continental margin is directly related to seafloor current dynamics. Yet the linkage between the processes remains vague due to the different time scales they represent. To narrow this gap we focus on the thoroughly studied distribution system of Nile derived sediments across the Levant continental margin (eastern Mediterranean). These sediments dominate the Late Quaternary stratigraphy of the entire margin. Their mobilization has been explained exclusively by longshore transport, while oceanographic evidence from the basin and margin are not incorporated in the known mechanism. New data indicates that longshore mechanism is part of a much larger system. Based on integrated interpretation of multibeam bathymetry, high-resolution single-channel seismic reflection and oceanographic (temperature, salinity and chlorophyll) data we suggest a jet current system mobilizes the Levant Surface Water (LSW), Levant Intermediate Water (LIW) and Atlantic Water (AW) northwards along the margin, between 0 and 400 m water depths. On the seafloor, contourite currents form elongated along-strike morphologies. Below 400 m along-dip gravity flows dominate sediment transport to down the slope, below the Eastern Mediterranean Deep Water (EMDW). Initiation of this mechanism during the Pleistocene–Holocene transition and not at the end of the Last Glacial Maximum (LGM) indicates a gradual recovery of the thermo-haline circulation. Current intensification in the early Holocene may have also increased water stratification. This comprehensive mechanism explains sediment transport along the entire depth range of the continental margin, while integrating seafloor currents, morphology, as well as their relation to sea level rise and stratigraphy of water masses in the Levant basin since the LGM. Given the consistency of seafloor currents throughout the Holocene we propose to address them as the Levant Jet System.

 Schematic illustration of seafloor currents flowing northwards along the Levant continental margin, presented over a slope shading of the bathymetry. Levantine Surface Water (LSW, light green) flows over B1. Part of it branches WNW south of the Carmel Structure (CS). The main flow crosses CS, deposits sediments over its northern flank and continues northwards to deposit unit S4 of Schattner et al. (2010). In Haifa Bay (HB) LSW branches eastwards, turns clockwise to the inner bay, where sediments are deposited (e.g., Zviely et al., 2007). LSW is then injected westwards and erodes the northern flank of CS into three bathymetric steps. Below, Atlantic Water mass (AW) flows along B2, between isobath contours of 80–130 m. Levantine Intermediate Water mass (LIW) follows the slope below AW. Both LIW and AW deflect locally over Palmahim slide (P). Close to the Carmel Structure, the continental slope steepens. AW and LIW project NNW. Below 350 m morphology of the continental slope shows down-slope features rather than along-slope. Numerous slumps (S) appear across the southern slope (SL1), while canyons (C) incise into the northern slope (SL2). White arrows mark down-slope sediment migration along the canyons and turbidite channels in the basin. D—Dor slide.

11:00-11:08 Galia Pasternak - Marine debris on the coast of Israel

Marine debris (litter) is a complex problem that affects human activities and the marine environment worldwide. On beaches, most studies have demonstrated densities in the 1 item m−2 order of magnitude, and an average of 75% of the debris plastic items. Success in keeping beaches clean is limited along the Mediterranean Sea; the Clean Coast Program in Israel has had some success in keeping most of the coasts clean most of the time. But questions regarding types of marine debris, their origin, distribution and vectors of transport in the coastal waters of Israel remain. In 2012, we initiated a study to characterize the types of marine debris, its origins and distribution in space and time. Nineteen surveys were done from June 2012 to March 2015 on eight beaches that spanned the coast of Israel during different sea conditions. The items found on the beach were categorized according to their material and use. In addition, the source of the debris was identified according to its country of origin, which is displayed in labels with the words "Made in ..." or based on the barcode on the product.

The results show average debris density of 11.1 items per 100 m², lower than the world average and 90% of the items were plastic. Over 58% of the coastal marine debris on the coasts of Israel is land-based, 5% of the debris was identified as sea-borne, and the source of the rest is uncertain (37%). The five main items found were plastic bags, disposable utensils, bottle caps and lids and cigarette butts. The composition of the major debris categories that we found on the Israeli coast differed from the global average and Mediterranean. The first difference is in the high percentage of plastic bags found in Israel which is more than three times the global average and more than twice as much as the Mediterranean. In contrast, Israel had nearly a third of the percentage of drinking bottles and cans compared to the global average and the Mediterranean. Percentages of food wrappers and disposables were similar between Israel and the Mediterranean and almost twice as high as the global average. The values for cigarette butts and bottle caps were similar among the 3 regions. The low amount of drinking bottles, as evidence of the effectiveness of the bottle recycling law, compared with the high percentage of plastic bags in Israel was used as part of the argument for new legislation to charge for plastic grocery bags in the Israeli parliament.

Top 5 items found along the Israeli coast vs. Mediterranean and global averages 

G. Pasternak ^a*, D. Zviely^b,c, C. A. Ribic^d, A. Ariel^e, E. Spanier^a,b

^a Department of Maritime Civilizations, The Leon H. Charney School for Marine Sciences, University of Haifa, Israel

^bThe Leon Recanati Institute for Maritime Studies, The Leon H. Charney School for Marine Sciences, University of Haifa, Israel

^cSchool of Marine Sciences, Ruppin Academic Center, Israel

^dUS Geological Survey, Wisconsin Cooperative Wildlife Research Unit, Department of Forest and Wildlife Ecology, University of Wisconsin, USA

 ^eEcoocean Marine Research and Education, Israel

*This email address is being protected from spambots. You need JavaScript enabled to view it.

11:10-11:18 Gilad Shtienberg - Late-Pleistocene evolution of the East Mediterranean shallow continental shelf of north-central Israel

Sea-level fluctuations are a dominant and dynamic mechanism that control coastal environmental through time. This is especially the case for the successive regressions and transgressions over the last interglacial cycle, which have shaped the deposition, preservation and erosion patterns of unconsolidated sediments currently submerged on continental shelves. The current study focuses on an integrated high-resolution marine and terrestrial litho-stratigraphic and geophysical framework of the north-central Mediterranean coastal zone of Israel. The interpretation enabled the reconstruction of the coastal evolution over the last ~130 ka.

A multi-disciplinary approach was applied by compiling existing elevation raster grids, bathymetric charts, detailed lithological borehole data-sets, a dense 110 km long sub-bottom geophysical survey and seven continuous boreholes sediment records. Based on seismic stratigraphic analysis, observed geometries, and reflective appearances, six bounding surfaces and seven seismic units were identified and characterized. Meanwhile, the chronostratigraphy of the terrestrial side was constructed through integration of magnetic susceptibility, sedimentological and geochemical analysis with 17 new OSL ages. The seismic units were correlated with the available terrestrial borehole data and then associated to the retrieved terrestrial chronostratigraphy to produce a 4D reconstruction model of the paleo-landscape.

The entire unconsolidated sequence overlies a calcareous aeolianite (locally named Kurkar unit) dated from ~130 - ~104 ka, which represents the top of the last interglacial cycle dune sediments. The lower unconsolidated unit consists of a red silty loam dated to ~71 ka. This Red-Paleosol unit is overlaid by a dark brown clayey silty loam This Brown-Paleosol unit dates to ~58 - ~36 ka and is overlaid by a dark silty clay wetland deposit dated to ~21 - ~10 ka. The wetland unit is topped by a quartz sand dated to ~6.6 - 0.1 ka.

This approach allowed us to investigate the relationship between the lithological units and sea-level change and thus enable the reconstruction of the coastal evolution over the last ~130 ka. This reconstruction suggests that the stratigraphy is dominated by a sea level lowstand during which aeolian, fluvial and paleosol sediments were deposited in a terrestrial environment. The coastal-terrestrial landscape was flooded by the early to middle Holocene transgression. The results of this study provide a valuable framework for future national strategic shallow-water infrastructure construction and also for the possible locations of past human settlements in relation to coastal evolution through time.

Isopach map of Hadera's seismic litho-stratigraphies. Each surface is presented with its corresponding seismic reflector and matching borehole-lithology. The litho-facies are presented from young (top left) to old (bottom right).

Gilad Shtienberg¹, Justin Dix², Nicolas Waldmann³, Yizhaq Makovsky³, Revital Bookman³, Joel Roskin^{1, 3, 5, 6}, Or M. Bialik³, Arik Golan⁴, and Dorit Sivan^{1, 5}

¹ Department of Maritime Civilizations, L. H. Charney School of Marine Sciences, University of Haifa, 31905 Haifa, Israel

²The School of Ocean and Earth, University of Southampton, Southampton SO14 3ZH, UK

³Dr. Moses Strauss Department of Marine Geosciences, L. H. Charney School of Marine SciencesUniversity of Haifa, 31905 Haifa, Israel

⁴Israel Oceanographic and Limnological Research Institute, 31080 Haifa, Israel

⁵The Recanati Institute for Maritime Studies (RIMS), University of Haifa, 31905 Haifa, Israel

 ⁶The School of Sciences, Achva Academic College, Israel

11:20-11:28 Benny Bechor - New estimates to Relative Sea Level for the last millennium in Greece, compared to the Israeli coast records

This research, presents an interdisciplinary study linking archaeological evidence with historical accounts and geological processes. The study aims to search for archaeological and historical indicators to relative sea level (RSL) from the 12^th Century to the early 17^th Century in the Peloponnese and Aegean islands mostly on Venetian coastal constructions, evaluation of the changes in sea level, consideration of tectonic and isostatic contributions, and comparison of these results with those from Israeli coast studies.

Greece and the Aegean islands were heavily investigated before by many other scholars, who traced after sea-level changes for the late Holocene, but without focusing on the last millennium. The current study performed new observations, after a site survey in several places in the Peloponnese, Crete and Paros island.

The new estimates combine archaeological markers along the coastline with historical records such as: ancient maps, panoramic views and eyewitness description, evaluations of dating and functional height of a specific archaeological indicators relative to the mean sea level (MSL) at the time of operation.

The tectonic contribution to RSL was evaluated using evidences of past earthquakes, from archaeological data and historical records. Although the study area is an active seismic zone with frequent earthquakes, this study did not indicate any influence of the seismic activity in the selected sites for the relevant period, and assumes that the tectonic contribution is negligible.

The contribution of glacial isostatic adjustment (GIA) to RSL was calculated by spatial analysis on the selected sites for the relevant elapsed time period, using the public domain SELEN program.

This study, produced an eustatic sea-level curve for the Venetian coastal structures in the Peloponnese and Aegean islands. The curve (Figure 1) exhibits lower sea-level by about -1.0m in the 12^th Century, climbing gradually to around -0.20m in the beginning of the 17^th Century.

Comparison between the current study sea-level curve with those made on the Israeli coast for the Medieval time using only archaeological indicators, as presented in the Figure 1, exhibits some similarities. The current observations confirmed low sea level in the mid-12^th Century, as observed in the Israeli coast in the mid-13^th Century and the results are correlated with the trend of global sea level changes, for the last Era, with larger data sets. Moreover, the data points of the current study manage to fill the gap of missing archaeological index points in the Israeli studies between the years 1250AD to 1700AD presented in Figure 1.

On other hand, current study could not corroborate sea levels observed in the Israeli coast earlier then the 12^th Century, probably due to shortage of archaeological sea level indicators (SLI) in Greece for this period.

Further high accuracy measurements are required, to better quantify of the East Mediterranean sea-level rise during the last millennium and to provide improved context for the assessment of the Medieval sea-level trends.

Figure 1: Comparison of archaeological sea level indications, of the current study in Greece (blue circles) and the Israeli coast data (pink circles)

11:30-11:38 Tuvia Dulin - My pet rocks: polytaxonomic reef nodules in the Akhziv Reserve

Macroids are semi-spherical calcium carbonate nodules produced by a variety of marine organisms. Different types of macroids include rhodoliths (made by coraline red algae), vermetuliths (made by vermetid molluscs), coraliths (made by corals), bryoliths (made by bryozoan colonies), and others. Typically, 90-95% of a macroid consists of limestone deposited by a single type of organism, though some include multiple species (rhodoliths in particular often have multiple red algae species growing together in a kind of symbiosis). Macroids typically form on otherwise barren seabeds that lack the stability and chemistry to support more conventional reefs. Macroids are also of great interest to paleontologists and paleogeologists, since the growing nodule tends to trap sediment grains and fossils within its volume. Since nodules can continue growing over the course of many centuries and have a clear internal stratigraphy, cutting one open can provide a thorough timeline of local oceanographic history.

In 2012, Dr’s Simona Avnaim-Katav and Guy Sisma accidentally discovered what appeared to be a vast field of rhodoliths on the seabed between the kurkar ridges of the Rosh Hanikra Islands, in the Akhziv nature reserve. Since the eastern Mediterranean is an oligotrophic area, rhodolith beds could represent a fairly important hotspot of photosynthesis that supports the surrounding ecosystems. There has been no research about rhodoliths off the Levantine coast; the closest study was one conducted in the Greek Marmara Sea in 1998. The biodiversity and fossil history of these ones was completely unknown. During the 2015 research cruise and again the following September, we collected a small sample of nodules from the site at Akhziv and brought them back to the University of Haifa in a pair of saltwater aquariums. We observed them and their encrusting floral and faunal communities, and then bisected them to examine the fossil record.

The outer surfaces of the nodules hosted very rich microhabitats filled with green, red, and brown algaes, molluscs, tunicates, crustaceans, foramanifera, sponges, and polychaetes. While many invasive species were found (par for the course, in the modern Mediterranean) they were outnumbered by natives in all categories besides the foramanifera, which could mean that these macroid bed ecosystems are an important refuge for native species that might otherwise be crowded out.

Upon bisection, it was discovered that these macroids weren’t actually rhodoliths at all, but something highly unusual in the existing literature. They were composed of alternating layers of red algae and serpulid tube worms with clear, sharp delineations between each successive layer. It was determined that abrupt changes in water conditions have caused these macroids to die and have their surfaces overtaken by different, better suited organisms many times over the past two to three hundred years. Periods of high water motion favor smooth algal growths as opposed to brachiated ones. Periods of high siltation and turbidity choke out the algae and allow a layer of tube worms to grow, while clearer water deprives the worms of their needed nutrients and allows the algae to return.

 Unfortunately, penetration of the macroids by boring molluscs made radiochemical dating impossible for our means.

11:40-11:48 Philip Nemoy - Integrated Multi Trophic Aquaculture: Red-to-Med

11:50-12:00 Dr. Dorit Sivan - From the last Interglacial (MIS5e, about 125ka ) to the last Millennium sea level data sets of Israel, East Mediterranean

The last interglacial (Marine Isotope Stage, MIS5e) marine-coastal sequence has been identified along the Galilee coast of Israel, with the type section located at Rosh Hanikra (RH). The RH-section comprises three main sub-units of a previously determined member (the Yasaf Member): (a) a gravelly unit containing the diagnostic gastropod Strombus bubonius (Persististrombus latus), which was deposited in the intertidal to super-tidal stormy zone; (b) Vermetidae reef domes indicating a shallow-water depositional environment; and (c) coarse to medium-sized, bioclastic sandstone, probably deposited in the shallow sub-tidal zone. The sequence overlies three abrasion platforms that are cut by tidal channels at elevations of +0.8 m, +2.6 m and +3.4 m, and which are filled with MIS5e sediments. Although without precise absolute dating, the stratigraphic sequence of RH through MIS5e allows us to identify a time-series of relative sea level (RSL) positions, using the elevations of three stratigraphic subunits. Reconstructed RSL values range from +1.0 m to +7 m (with uncertainly < 1m), and most fall within a narrow range of +1.0 to +3.3 m. Toward the end of MIS5e, RSL rose to about +7 m. Glacial isostatic adjustment (GIA) modelling using multiple ice histories suggests that GIA corrections range between about -1.8 m and +5.4 m. This implies that global mean sea level varied between -0.8 m and +8.7 m during most of MIS5e. The absolute GIA correction would not have been constant through the interglacial (Sivan et al., submitted).

Following the MIS5e, sea level fell and rose again after the last Glacial Maximum (LGM). In the Holocene, the Israeli sea-level curve is based mainly on archaeological data. It is also constrained by model prediction (Sivan et al., 2001). Several studies indicate that the sea reached its present level along the coast of Israel between 4000 and 3600 years ago (Sivan et al., 2001; Porat et al., 2008). During the last 2500 years RSL fluctuated mainly below present levels (Sivan et al., 2004; Toker et al., 2012). Based on the fact that the coast of Israel was found to be stable, and the vertical isostatic induced rates were negligible (Sivan et al., 2001; 2004; Toker et al., 2011), the observed RSL was actually eustatic. For the last Millennium, bio-constructions are also used as RSL indicators (Dendropoma petraeum reefs at the edge of the abrasion platform along the Israeli coast).

Until now, we have collected 139 archaeological indicators in Israel, and of them 121 were deemed reliable enough for reconstructions. The Israeli database also includes 31 index points based on Dendropoma reefs. We then carried out an assessment of reliability procedure giving a simple score to each indicator, and therefore we can state that the sea level data are reliable. The data will be soon be analysed statistically to enable a better comparison to larger-scale datasets.

References

Porat, N., Sivan, D., Zviely, D. 2008. Late Holocene embayment and sedimentological infill processes in Haifa Bay, SE Mediterranean. Israel Journal of Earth Sciences 57: 21-23.

Sivan, D., Wdowinski, S., Lamback, K., Galili, E., and Raban, A. 2001. Holocene sea-level changes along the Mediterranean coast of Israel, based on archaeological observations and Numerical model. Palaeogeography, Palaeoclimatology, Palaeoecology. 167, 101-117.

Sivan, D., Lambeck, K., Toueg, R., Raban, A., Porat, Y. and Shirman, B. 2004. Ancient coastal wells of Caesarea Maritima, Israel, an indicator for sea level changes during the last 2000 years. Earth and Planetary Science Letters 222, 315-330.

Sivan, D., Schattner, U., Morhange, C., Boaretto, E. 2010. What can a sessile mollusk tell about the Neotectonics of Eastern Mediterranean? Earth and Planetary Science Letters (EPSL), 296, 3-4, 451-458.

Sivan D., Sisma-Ventura G., Greenbaum N.,  Bialik O.M., Williams, F.H,. Tamisiea,M.E,, Rohling, E.J.,  Frumkin, A., Avnaim-Katav S., Shtienberg G., Stein M. Submitted. Eastern Mediterranean sea levels through the last interglacial from a coastal-marine sequence in northern Israel. Quaternary Science Reviews.

Toker, E., Sivan, D., Stern, E., Shirman, B. Tsimplis, M., Spada, G. 2012. Evidence for centennial scale sea level variability during the Medieval Climate Optimum (Crusader Period) in Israel, eastern Mediterranean. Earth and Planetary Science Letters, 315-316, 51-61.

12:10-12:18 Omri Gadol - Very high resolution multi-channel deep water profiling

12:20-12:28 Allaka Himabindu - Motion Assesment of Planing Craft In Seaway

A nonlinear mathematical model for the simulation of motions and accelerations of planing monohulls, having a constant deadrise angle, in head waves has been formulated. The model is based on 2-dimensional strip theory. The model follows the principles of pioneering work of E.E.Zarnick [3, 4]. The simulations can be carried out for a planing boat sailing in regular and irregular head seas, using a constant forward speed. The hydromechanic coefficients in the equations of motion are determined by a combination of theoretical and empirical relationships. The sectional hydromechanic forces are determined by the theory of a wedge penetrating a water surface. The wave excitation in vertical direction is directly integrated in the expressions for the hydromechanic forces and is caused by the vertical orbital velocity in the wave and the geometrical properties of the wave, altering the total wetted length and the sectional wetted breadth and immersion. The wave induced heave, pitch motions and vertical accelerations calculated are compared with the experiments by Fridsma [1].

Planning hull Mathematical modelling

For analysis and simulation of nonlinear planing hull dynamics a mathematical model, following the work of Zarnick [3,4] is developed. Coordinate system For the definition of the mathematical model is necessary to define reference systems as shown in Figure1, The forces acting on a planing hull in calm sea conditions are: weight of the ship W , shaft thrust T, Frictional drag force along the hull D, Normal force on the planning hull (hydrodynamic force FHD, hydrostatic component FHS and Cross-flow drag FCD) as schematized in Figure2ץ

Equations of motion 

In the present study only the equations of motion in vertical plane are considered. The Surge xCG, Heave zCG and Pitch θ motion equations are written as: 

Results

Computation of Time histories for Pitch and Heave motions, Bow and Center of Gravity(CG) accelerations were performed to compare with Zarnick’s model Figure-3,4. The results are in exact match with Zarnick’s model. Below some of the results for Regular waves and irregular waves, with deadrise β = 20o , √ V L = 6 , λ L = 4, Wave height H = 2.54cm(1in). The comparison of computed results with experimental work of Fridsma [1] is done Figure-5,6. 

References 

[1] G. Fridsma, S. S. Command, and C. Station, “A systematic study of the rough-water performanceof planning boats,”Tech. Rep. 1275, Davidson Lab. Stevens Institue Technol. Hoboken, NJ, USA, 1969.

[2] G. Fridsma, “A systematic study of the rough-water performance of planning boats(irregular waves—part II),” Tech.Rep.11495, Davidson Lab. Stevens Institue Technol. Hoboken, NJ, USA, 1971.

[3] E. E. Zarnick, “A non-linear mathemathical model of motions of a planning boat in regular waves,” Tech. Rep.DTNSRDC- 78/032, David Taylor Nav. Sh. Reasearch Dev. Center, Bethesda, Md, USA, 1978.

[4] E. E. Zarnick, “A non-linear mathemathical model of motions of a planning boat in irregular waves,” Tech. Rep.DTNSRDC- 78/032, David Taylor Nav. Sh. Reasearch Dev. Center, Bethesda, Md, USA, 1979.

12:30-12:38 Dana Berman - Physics-Based Single Underwater Image Restoration

Underwater images suffer from low contrast and color distortions [3]. In addition, the ambient illumination of the scene is predominantly blue, and this phenomenon increases with the depth. Both the contrast degradation and the color shifts depend on the distance of the objects in the scene from the camera. Because different points in the scene are located at different distances, the color distortion and loss of contrast cannot be compensated for globally. As a result, many underwater images appear blue and lack vivid colors.

Nevertheless, color and contrast are extremely important for visual surveys in the ocean. For example, enhanced images can improve automatic segmentation, increase the quality of feature matching between images taken from multiple viewpoints, and aid in identification.

In this paper we aim to recover the objects colors and distances in scenes photographed under ambient illumination in water using solely a single image as an input.

When taking terrestrial photos under bad weather conditions, such as haze or fog, image contrast is lost and the colors are distorted, albeit less severely than under water. This degradation is also distance-dependent. Therefore, underwater image restoration and haze removal are closely related problems. A variety of methods have been developed recently for the single image haze-removal problem. The methods assume that the color distortion is uniform for the different color channels. Although this assumption was previously used in attempts to correct underwater scenes, it simply does not hold in practice.

Jerlov [2] developed a frequently used classification scheme for oceanic waters, based on water clarity and turbidity. For each water type, the color-dependent distortion was measured.

We extend a single image dehazing technique [1] to incorporate a color-dependent dis- tortion, and use the measurement of the different water types in order to restore the colors, based on a physical image formation model.

Fig. 1(a) shows an example of an underwater scene, where five identical color charts were placed at different distances from the camera. The color charts are enlarged below the scene, from left to right in increasing distance from the camera. The contrast degradation and color distortion increase with the distance. Therefore, the image contrast of the color charts decreases from left to right. In addition, the red color, which is evident in the leftmost square at the middle row, gradually disappears as the color charts are located at greater distances.

Since the color charts are identical, the output of an ideal color restoration algorithm is an image where all color charts look the same. Out result is shown in Fig 1(b). This results was obtained from a single image, take with a commercial camera, without using any external devices. The colors of the distant charts and their contrast are enhanced compared to the input.

Our method performs single image restoration of underwater scenes using the full physical image formation model. Thus, we are able to recover complex 3D scenes and, in addition, estimate the water properties.

Dana Berman, Tali Treibitz, Shai Avidan

Figure 1: An underwater scene is imaged using ambient light. The image is shown (a) before and (b) after our color restoration process. Five identical color charts were placed at the scene, located at different distances from the camera, approximately 2 meters apart. The depth of the scene is approximately 10 meters. In addition to the entire scene, a zoom-in on the color charts is shown, from left to right in increasing distance form the camera. A global contrast stretch was applied to both images.

References

[1] Dana Berman, Tali Treibitz, and Shai Avidan. Non-local image dehazing. In Proc. IEEE CVPR, page Supplied as additional material cvpr16.pdf, 2016.

[2] Nils Gunnar Jerlov. Marine optics, volume 14. Elsevier, 1976.

[3] Curtis D Mobley. Light and water: radiative transfer in natural waters. Academic press, 1994.

12:40-12:48 Dr. Tali Treibitz - Advances in Marine Imaging and Computer Vision

As human access to most of the ocean is very limited, novel imaging systems and computer vision methods have the potential to reveal new information about the ocean that is currently unknown. In the talk I will give an overview of our current efforts in the field, including image enhancement, using fluorescence for coral recruit surveys and in situ microscopy.

13:00-13:08 Yotam Popovich - Observation Based Science As A Tool For Deep Mediterranean Management And Conservation

The need for science based management of the overcrowded Deep Mediterranean is strongly emerging as anthropogenic pressure and competition over EEZ resources soar. Although the EEZ draws a big economic interest, very little is known about its biology. Recent reports (Israel Marine Plan, IOLR) emphasized the need for strong, observational based, baseline in this patchy environment. This talk will feature two unique examples studied by utilizing ROV's for observation and guided sampling.

The colonial black corals (Leiopathidae, Antipatharia) were collected at ~700m bsl within the Palmachim disturbance. The Leiopathes relies on its L/D ratio in order to maximize its capture rate efficiency by reducing the critical Reynolds number, thus enabling high mixing rate and turbulence for each individual branch. The long interweaving branches and the perpendicular branchlets create a designated mesh for freshly exported  POM capture, yet brachlets are separated enough to allow high leakiness as if the colony is sweeping through the water, actively foraging.

Spionidae (Prionospio sp) worms, a family within the Polychaeta, were observed across the shores of Palmachim and Acre, inhabiting hydrocarbon enriched euxinic sediment, ~ 1000 m bsl. Methane bubbling within the dense populated patch, a resuspended organic matter source, has triggered the spionids to move their upper body part and palps in an oscillatory “rocking” manner. Particle capture efficiency and stress components were calculated and used to assess changes to the spionids' immediate environment and the energy gained by oscillating. The oscillation also generated a lateral flow component that removed vortex-trapped particles, being beneficial to the spionid and increasing metabolic activity of associated thiotrophic bacteria. The ability of these bacteria to detoxify sulfide and provide additional nutrition may contribute to the success of the spionids. These bacteria may represent keystone species in the euxinic patches.

Only by utilizing eyes and hands in the patchy nonuniform Deep Mediterranean, one can create a science based tool for managing the EEZ.

Yotam Popovich ,Eli Shemesh, Dan Tchernov

13:10-13:18 Niv David - Sea-level rise effects on biodiversity of vermetid reefs

13:20-13:28 Maya Britstein - Host-microbe symbiosis in the Mediterranean sponge Petrosia ficiformis

Symbiosis is defined as “the living together of unlike organisms”. In recent years it has become more and more evident that the symbiosis of animals with microorganisms has profound impact on their health. In this study we use marine sponges and their symbionts (microorganisms living in association with the sponge) as a model system to better understand how an animal host and the microorganisms that inhabit its body interact. Specifically, we are interested in understanding how an animal host recognizes, interacts and controls the microbial community that inhabits its body. Sponges form close associations with a wide variety of microorganisms (including algae, bacteria and fungi) and need to establish a stable and healthy associations with its symbiotic microorganisms, at the same time, sponges need to discern the symbiotic microorganisms from food and pathogen microbes. The facultative association of the Mediterranean sponge Petrosia ficiformis with the photosynthetic cyanobacteria Candidatus Synechococcus feldmannii, is the focus of this study. This sponge hosts a diverse assemblage of bacteria, including, in illuminated sites, the endocellular Ca. S. feldmanni (photosynthetic bacteria). This sponge is found in the natural environment in three colors according to the sunlight intensity where the sponge grows; violet-wine red color when it is exposed to a lot of light (figure A), pink when it settles in dim light locations (B) and white when growing in complete darkness, such as underwater caves (C). The color is provided to the sponges by the symbiotic cyanobacteria Ca. S. feldmanni. In this study we focus on the pink and the white sponges. We have the ability to manipulate the pink sponge to become white (i.e., lose its symbiotic cyanobacteria) by taking a piece of the sponge and moving it from light to dark underwater conditions, such as in a cave (D). The lack of light causes the loss of the photosynthetic symbionts from the sponge, within few months (E). In this project we also provided evidence, for the first time, that when white sponges were moved to light conditions they could acquire the cyanobacteria in a period of eight months (F and G). Such transplant experiments enable us to investigate the effect of cyanobacteria on the sponge in terms of sponge-gene transcription, host-microbe metabolic integration, and microbial community composition.

 P. ficiformis showing the three morphs: (A) White color morph living in dark condition. (B) Pink color living in dim-light conditions. (C) Violet color morph living in light-areas; Transplanted P. ficiformis specimens. (D) Pink morph, directly after transformation to a dark cave. (E) Pink morphs that became white after a period of four months. (F) White specimens directly after transplantation outside the cave. (G) White specimens showing potential uptake of cyanobacteria based on change in pigmentation (arrows).

13:30-13:38 Lama Khalaily - The Upstream of the Vascular Endothelial Growth Factor (VEGF) during sea urchin skeletogenesis

Understanding how signaling pathways regulate cell fate specification and organogenesis is an essential step toward deciphering the molecular control of embryo development. Many of these signaling pathways are conserved; they are crucial and fundamental in every embryo development and control various developmental processes. Specifically, Vascular Endothelial Growth Factor (VEGF) signaling pathway regulates vascularization and angiogenesis in vertebrates. In the sea urchin embryo that does not have a vascular system, VEGF signaling is critical for larval skeletogenesis. Little is known about VEGF upstream regulation mechanisms in the sea urchin embryo and how is compared with its activation in vertebrates. Here we aim to reveal the upstream regulation mechanisms that control VEGF expression in the sea urchin embryo, the implications of this study will assist in understanding the common regulation mechanism of VEGF signaling in the vascularization process in human, and the skeletogenesis in sea urchin.

13:40-13:48 Dr. Daniel Sher - From microscale interactions between marine bacteria to global models