Lake Kinneret Research Articles

Art Notes: Mysteries within Rembrandt's Christ in the Storm on the Sea of Galilee

Art Notes: Mysteries within Rembrandt's Christ in the Storm on the Sea of Galilee

A hypervariable intron of the STAYGREEN locus provides excellent discrimination among Pisum fulvum accessions and reveals evidence for a relatively recent hybridization event with Pisum sativum.

An analysis of 82 non-synonymous Pisum fulvum accessions for sequence variation in a fragment of the STAYGREEN (SGR) locus revealed 57 alleles, most of which differed in indel structure. Eight additional P. fulvum accessions, each supposedly synonymous with a different accession of the initial group, were also analyzed. In every case the paired synonymous accessions possessed the same SGR sequence but varied slightly for a 6-trait morphological phenotype, indicating that SGR sequence is a much more reliable indicator of accession identity than is a morphological characterization. SGR sequence analysis confirmed our previous finding that P. fulvum accessions separate into two allele groups. This division was not supported by results of previous studies that were based on sequences distributed across the entire genome, suggesting that the division may have been produced by selection at a nearby locus and that the SGR phylogeny may not be good indicator of overall relationships within the species. One P. fulvum accession, PI 595941 (=JI1796), displayed an SGR sequence outside the variation typical of the species. Instead, its allele resembled alleles limited to a set of Pisum sativum landraces from the Middle East, suggesting hybridization between ancestors of PI 595941 and some primitive form of domesticated P. sativum. With one exception from the extreme northwest corner of Israel, P. fulvum accessions collected north of latitude 35.5° N were fixed for alleles from group A. These northern accessions also displayed greatly reduced SGR sequence diversity compared to group A accessions collected from other regions, suggesting that the northern populations may represent recent extensions of the range of the species. Group B accessions were distributed from Lake Tiberias south and were generally sympatric with the southern group A accessions. Although group B accessions occupied a smaller area than group A, the SGR sequence diversity in this group (28 alleles in 33 accessions) exceeded that for group A.

Crustal Structure Across the Central Dead Sea Transform and Surrounding Areas: Insights Into Tectonic Processes in Continental Transforms

AbstractNew geophysical profiles across the central Dead Sea Transform (DST) near the Sea of Galilee, Israel, and surrounding highlands, augmented by static stress modeling, allow us to study continental transform plate deformation. The DST separates a ∼10 km thick sedimentary column above a thinned (16–23 km) crust to the west from a ∼7 km column above a ∼30‐km thick crust to the east. Crustal thinning starts under the DST, as observed also farther south, indicating that the DST is indeed located along the boundary between the Arabian plate and its continental margin. Moho step here is gradual. The DST's eastern shoulder dips westward toward the DST unlike the upward flexed shoulder observed farther south, perhaps delineating the northern limit of a thinner and hotter lithosphere. The shape of the Sea of Galilee is modeled as an asymmetric pull‐apart basin formed by a left‐lateral stepover of 2.6 km between slightly divergent and underlapping strike‐slip fault strands dipping 70° to the west. Reflection data indicate that these strands are not connected. Several fault traces within the Sea of Galilee have previously been suggested to carry part of the relative plate motion. However, given slip along the main DST faults, Coulomb stress will increase only on fault portions in the northern part of the lake, in accord with the geographical distribution of seismicity, suggesting that these faults are likely secondary. Mismatch between the DST strand locations in the geophysical profiles and the subsidence model, may reflect temporal changes in fault geometry.

Hydantoanabaenopeptins from Lake Kinneret Microcystis Bloom, Isolation, and Structure Elucidation of the Possible Intermediates in the Anabaenopeptins Biosynthesis.

Anabaenopeptins are common metabolites of cyanobacteria. In the course of reisolation of the known aeruginosins KT608A and KT608B for bioassay studies, we noticed the presence of some unknown anabaenopeptins in the extract of a Microcystis cell mass collected during the 2016 spring bloom event in Lake Kinneret, Israel. The 1H NMR spectra of some of these compounds presented a significant difference in the appearance of the ureido bridge protons, and their molecular masses did not match any one of the 152 known anabaenopeptins. Analyses of the 1D and 2D NMR, HRMS, and MS/MS spectra of the new compounds revealed their structures as the hydantoin derivatives of anabaenopeptins A, B, F, and 1[Dht]-anabaenopeptin A and oscillamide Y (1, 2, 3, 6, and 4, respectively) and a new anabaenopeptin, 1[Dht]-anabaenopeptin A (5). The known anabaenopeptins A, B, and F and oscillamide Y (7, 8, 9, and 10, respectively) were present in the extract as well. We propose that 1-4 and 6 are the possible missing intermediates in the previously proposed partial biosynthesis route to the anabaenopeptins. Compounds 1-6 were tested for inhibition of the serine proteases trypsin and chymotrypsin and found inactive at a final concentration of ca. 54 μM.

Low prevalence of Contracaecum third-stage larvae parasitizing Sea of Galilee fisheries: 1-year survey after 57 years of no information

Freshwater and marine ecosystems are a suitable habitat for parasitic nematodes of the genus Contracaecum (family: Anisakidae) to complete their complex life cycle. Several fish species of the Sea of Galilee (Lake Kinneret) were reported in 1964 as second intermediate/paratenic hosts of Contracaecum spp. larvae. The lack of taxonomically relevant morphological features of these larvae hindered their proper identification. Here we report the results of a 1-year survey conducted in 2021, 57 years after the first (and only) such survey. We analyzed 352 specimens from 10 fish species (native and non-native) of the Sea of Galilee (Israel) ichthyofauna. We compared our results with those of the first parasitological survey conducted by Paperna in 1964; the overall prevalence of nematodes referable to Contracaecum larvae was 16.8% and 0.85% in 1964 and in 2021, respectively. Different from the first survey that identified Contracaecum larvae morphologically, we used both morphological and molecular tools. Two wild native cyprinids—Jordan himri (Carasobarbus canis) and Jordan barbel (Luciobarbus longiceps)—were infected (a single specimen each) with Contracaecum quadripapillatum larvae in their abdominal cavity. A single specimen of blue tilapia (Oreochromis aureus) was infected with two larvae of Contracaecum multipapillatum E, localized in the pericardial cavity. The findings of our study, which is part of a large project focused on Contracaecum spp. infecting both piscivorous birds and fish collected in Israel, advance our knowledge about the distribution and host range of this potentially zoonotic parasite in fishery products of the Sea of Galilee.

Biodiversity during Pre and Post Hula Valley (Israel) Drainage

The natural ecosystem of the Hula Valley (Israel) comprising shallow old lake Hula, swamps and partly cultivated land was altered by drainage. The drained area was converted for agricultural development. The natural wetland–lake ecosystem was demolished. A reduction in biodiversity and a negative impact on the downstream Lake Kinneret water quality were predicted. Forty years later, a reclamation project was implemented aimed at renovation of the hydrological conditions, and agricultural development was improved. The recorded inventory of plants, birds and fish pre- and post-drainage and reclamation was comparatively evaluated resulting in an indication of Biodiversity Index (BDI) and Species Richness (SR) enhancement in the present. It is suggested that the resulting increase in ecological habitat varieties suitable for terrestrial, semi-aquatic and aquatic organisms enhanced the biodiversity. Nevertheless, it is not impossible that the newly created conditions which enhanced the biodiversity require a risk assessment to ensure the long-term sustainability of the integration of agriculture and nature.

Biocontrol Potential of Novel Borrelidin-Producing <i>Streptomyces rochei</i> 3IZ-6 Isolated from Izraeli Soil

The soil actinobiota of various climatic zones are a rich source of bioactive natural products, including novel drugs. A complex of soil actinomycetes in the upper horizon of the grumusols (Vertisols) on the western coast of Lake Kinneret in the vicinity of Tiberias (Lower Galilee, Israel) was studied. The screening of the antagonistic activity of 26 isolates using on a dual reporter system revealed the bacterial strain 3IZ-6, which had the ability to inhibit protein synthesis. Strain 3IZ-6 was assigned to Streptomyces rochei by polyphase taxonomy approach. The active substance of S. rochei 3IZ-6 was isolated and purified using solid-phase extraction and HPLC. Toe-print analysis and mass spectrometry data allowed to establish, that active compound is a known inhibitor of protein biosynthesis, borrelidin. S. rochei 3IZ-6 can be used as a producer of borrelidin in biocontrol against phytopathogens and weeds.

BTEX and PAH contributions to Lake Kinneret water: a seasonal-based study of volatile and semi-volatile anthropogenic pollutants in freshwater sources.

Benzene , toluene, ethylbenzene, and xylenes (BTEX) BTEX molecules are toxic components, ubiquitous in the environment, often found in concentrations- a few orders of magnitude higher than the well-studied PAHs levels. This fact is demonstrated in either crude oil, fuels, water, and air samples. BTEX studies focus mainly on the airborne levels of these molecules, while their waterborne presence is understudied. In this study, BTEX levels were assessed at Lake Kinneret, Israel. As a result, 0-1.5ppb of BTEX was recorded in five stations (2021-2022). Elevated BTEX levels (3-10ppb) were recorded at the northern rivers nourishing this lake, implying the existence of remote polluting sources. Transect air samplings of BTEX conducted at the lake next to the bathing season of 2021 revealed airborne BTEX levels between 0.8 and 10µg/m3, peaking up close to the bathing season, yet inconsistent with the BTEX water level trend. Lake water samples collected next to Tiberias city outfalls following the "Carmel" rainstorm showed elevated concentrations of BTEX up to 35ppb and PAHs up to 0.47ppb with an urban isotopic signal. The remote station's PAHs levels were less than one order of magnitude, with a distinct rural isotopic signal. Additionally, a human-specific microbial marker revealed increased sewer contributions at some of theurbansites. The results of this study show that a wide area dispersion of low atmospheric BTEX levels exists in the lake's perimeter. The dispersion rate is most likely influenced by season-based factors, e.g., motors and biomass fires. The unstudied waterborneBTEX levels in this lake are influenced by rivers, city runoff, and other yet unknown factors that may contribute to the sedimentation of these components. This process may result in a chronic pollution state. Despite the BTEX's medium-low solubility and high volatility, its under-evaluated waterborne transportation may lead to high toxic levels following bioaccumulation.

Are Water Level Fluctuations and Pelagic Water Quality in Lake Kinneret Directly Related? Perspectives of Nutrient Dynamics

Long-term records of Water Level Fluctuations (WLF) and nutrient dynamics in Lake Kinneret have indicated an independence between them. The winter’s high WLF with nutrient-rich conditions and the summer’s low WLF with nutrient-poor conditions are recurrent states. Are Water Level Fluctuations and Lake Kinneret’s pelagic water quality related directly or indirectly? Overall, the results found that WLF and nutrient dynamics in the pelagic zone of Lake Kinneret are not co-partners, but independent escorts. The common periodical (monthly) distribution of nutrient concentrations in the epilimnion of Lake Kinneret indicates that a 20 m deep epilimnion formed following a decline in water input, temperature, and evaporation elevation, resulting in the decline of WL. There was a seasonal correlation between summer’s natural conditions and pelagic nutrients’ deficiency. Low WL in summer is the result of natural subtropical climate conditions, whilst dry or high rainfall seasons induce water input modification and consequently, the WL decline of nutrient inputs and independent followers.

Modal structure of the sound field in a shallow-water waveguide with a gassy sediment layer: Experiment and theory

Motivated by a series of experiments in the Lake Kinneret (Israel), the paper investigates low-frequency sound propagation in the three-layer model of the shallow water waveguide, where a thin layer of gas-saturated sediment is situated between a homogeneous fluid sub-bottom and a continuously stratified water column. Typical values of the thickness and sound speed in the gassy layer are 1 m and 250 m/s. The layer is thin compared to typical water depth of about 40 m. Normal mode structure of the acoustic field is analyzed. It is shown that with increasing frequency each normal mode transforms into a mode trapped in the gassy layer. These modes have unusually small phase and group speeds that are significantly less than the sound speed in water. Theoretically predicted normal mode dispersion curves are compared to the dispersion curves retrieved from observations of shipping noise. Phase speeds of normal modes are measured by cross-correlatingthe noise recorded on two sparse vertical arrays. A technique is proposed for solving the inverse problem of determining the parameters of a gas-saturated layer by matching the measured and modeled frequency dependencies of the normal mode phase speed.

Rifting‐Driven Magmatism Along the Dead Sea Continental Transform Fault

AbstractThe Dead Sea Fault (DSF) is a crustal‐scale continental transform fault separating the African and the Arabian plates. Neogene to Quaternary volcanic activity is well‐spread in Northern Israel. Yet, the origin of the magmas that fed the eruptions is still unpinned. Our local earthquake tomography depicts velocity distributions typical of rifting settings. At 9 km depth, a prominent high Vp/Vs anomaly marks the presence of cooling melts. We propose that protracted transtension along the DSF caused crustal thinning promoting the emplacement of magmatic bodies. Crustal emplacements of magmas in Northern Israel reconcile multiple observations, including the high geothermal gradient, the prominent magnetic anomalies and the traces of mantle‐derived fluids in the springs across the Sea of Galilee. We provide a compelling evidence for rifting in segments of the DSF and identify the potential source of magmatism that fed part of the volcanic activity of the area.

Historical Review on Water Level Changes in Lake Kinneret (Israel) and Incomparable Perspectives

A long-term (1933–2022) record of water level (WL) fluctuations in Lake Kinneret was reviewed. The dependence of the Kinneret WL management on climate change (flood–dryness alternate), dam and National Water Carrier (NWC) constructions constrained by water availability and domestic supply demands were indicated. A short-term range of maximal WL decline of 4–6 m and 4.6–6.5% of the total surface area of lake water shrinkage in Lake Kinneret was documented. Nevertheless, incomparably longer periods and higher amplitudes of WL decline accompanied by a dramatic shrinking of the water surface were documented in Lake Tchad, the Aral Sea and Lake Sivan (SAT). Therefore, the comparative results of WL decline in Lake Kinneret and in other lakes as SAT are not justified.

The Borderlands

The Borderlands

Gloeotrichia pisum in Lake Kinneret: A successful epiphytic cyanobacterium.

With climate change and re-oligotrophication of lakes due to restoration efforts, the relative importance of benthic cyanobacteria is increasing, but they are much less studied than their planktonic counterparts. Following a major water level rise event that inundated massive reed stands in Lake Kinneret, Israel, we discovered the appearance of a vast abundance of Gloeotrichia pisum (cyanobacteria). This provided an opportunity to investigate the biology and ecology of a benthic epiphytic colonial cyanobacterium, proliferating under altered environmental conditions, with possible toxin production potential and as a model for an invasive epiphyte. The species was identified by its typical morphology, and by sequencing its 16S rRNA gene and the intragenic space. We report on the abundance and spatial distribution of the detected colonies, their morphological characteristics, and pigment composition. High phycoerythrin content provides a brownish color and supports growth at low light levels. Genomic community composition analysis revealed that G. pisum colonies host a diverse microbial community of microalgae, cyanobacteria, bacteria, and archaea with a conserved and characteristic taxonomic composition. The Synechococcales order showed high relative abundance in the colony, as well as other prokaryotes producing secondary metabolites, such as the rhodopsin producer Pseudorhodobacter. The microbial consortium in the colonies performed nitrogen fixation. The diazotroph's phylogenetic relations were demonstrated. Tests for the presence of cyanotoxins (microcystin and cylindrospermopsin) proved negative. This study is the first documentation of this genus in Israel, providing insights into the invasive nature of G. pisum and the ecological implications of its appearance in a lake ecosystem.

First Evidence of Trade in Galilean Salted Fish on the Carmel Coast in the Early Islamic Period

The production and maritime trade of salted-fish products are well documented in the western Mediterranean during the Classical and Roman periods. Ichthyological remains found within amphorae in shipwrecks and other archaeological contexts provide evidence for long-distance exchange based on the biogeographical distributions of fish species. The Ma‘agan Mikhael B shipwreck (mid-seventh to mid-eighth centuryad) found on the Carmel coast of Israel held three Late Roman amphorae which contained the remains of small fish. The identified species suggest a previously unknown fish-salting operation at the Sea of Galilee during the early Islamic period. The evidence also points to a distribution or trade centre for salted fish at Caesarea-Maritima after the transition to Islamic rule in the eastern Mediterranean. The results of this study demonstrate the value of archaeozoological methods applied to maritime archaeological contexts, attesting to production and trade activities that left few traces in the archaeological record of antiquity.

The microbial community spatially varies during a Microcystis bloom event in Lake Kinneret

Abstract Cyanobacterial blooms in lakes frequently display high spatial heterogeneity, which may drive temporal changes in microbial community structure. Here we report on the spatial (horizontal and vertical) structure of the cyanobacteria community and of the co‐occurring heterotroph microbial community during a major lake‐wide bloom event at Lake Kinneret (Sea of Galilee, Israel). We sampled the upper water layer (0, 1 and 5 m depths) at five locations across the lake, spatially representing north, south, east, west and centre of the lake, on two dates during winter 2016 when the Microcystis biomass was high. We aimed to characterise the spatial distribution of the bloom and the associated microbiota, as well as testing the extent to which variation in the structure of the microbial community could be associated with Microcystis biomass. During the winter 2016 bloom, Microcystis biomass was spatially heterogeneous, but the Microcystis population structure was rather homogenous, dominated by a single genotype (ITS sequence variant). By contrast, the composition of the bacterial community, assessed using 16S rRNA gene sequencing, was spatially heterogeneous, differing between depths, sampling locations and time. The largest difference in microbial community structure was between particle‐associated (PA) and free‐living (FL) fractions. The PA community was characterised by a relatively lower diversity, and dominated by Proteobacteria, whereas the FL community was significantly more diverse and dominated by members of Proteobacteria, Bacteroidetes and Actinobacteria. Variation in the microbial community was significantly correlated with geographical location and sampling depth. However, there was no clear relationship between the Microcystis biomass density (cells biovolume) and the structure of the microbial communities. These results suggest that the structure of the bacterial community is partly decoupled from Microcystis population density, and potentially more affected by other environmental factors such as temperature and/or physicochemical conditions. Our study highlights the importance of spatial information on bloom composition and intensity in clarifying the factors affecting the progression of cyanobacterial harmful algal blooms and how this impacts their microbial counterparts.

Applying the Safe Operating Space (SOS) Approach to Sustainable Commercial Fishing under Varying Lake Levels and Littoral Zone Conditions

Successful management of lake ecosystems and the ecosystem services they provide necessitates ecosystem‐based management. The application of ecosystem‐based management can assist in achieving sustainable management of the ecosystem to ensure continued and sustainable supply of ecosystem services such as fisheries. One concept for defining sustainable fishing is the Safe Operating Space (SOS). In our study, we apply the Ecopath with Ecosim suite of models to predict the SOS required for the management of a commercial fishery. We use the Lake Kinneret (Israel) ecosystem as a case study to illustrate the approach by developing an Ecospace model of the lake and incorporating the spatio‐temporal framework and varying environmental conditions. We test, and demonstrate, the methodology for developing a SOS for a commercial fish population that can be implemented by lake managers elsewhere and illustrate it's use by defining example target values of biomass (e.g., 200 and 250 tons) and catch (e.g., 125 tons/year). Our results show that the SOS for a given target can be defined by a range of fishing efforts and vegetation cover in the lake as a function of lake level. The complexity in defining the actual values highlight the benefit of the approach we present here.

Multi-model projections of future evaporation in a sub-tropical lake

Lake evaporation plays an important role in the water budget of lakes. Predicting lake evaporation responses to climate change is thus of paramount importance for the planning of mitigation and adaption strategies. However, most studies that have simulated climate change impacts on lake evaporation have typically utilised a single mechanistic model. Whilst such studies have merit, projected changes in lake evaporation from any single lake model can be considered uncertain. To better understand evaporation responses to climate change, a multi-model approach (i.e., where a range of projections are considered), is desirable. In this study, we present such multi-model analysis, where five lake models forced by four different climate model projections are used to simulate historic and future change (1901–2099) in lake evaporation. Our investigation, which focuses on sub-tropical Lake Kinneret (Israel), suggested considerable differences in simulated evaporation rates among the models, with the annual average evaporation rates varying between 1232 mm year−1 and 2608 mm year−1 during the historic period (1901–2005). We explored these differences by comparing the models with reference evaporation rates estimated using in-situ data (2000–2005) and a bulk aerodynamic algorithm. We found that the model ensemble generally captured the intra-annual variability in reference evaporation rates, and compared well at seasonal timescales (RMSEc = 0.19, R = 0.92). Using the model ensemble, we then projected future change in evaporation rates under three different Representative Concentration Pathway (RCP) scenarios: RCP 2.6, 6.0 and 8.5. Our projections indicated that, by the end of the 21st century (2070–2099), annual average evaporation rates would increase in Lake Kinneret by 9–22 % under RCPs 2.6–8.5. When compared with projected regional declines in precipitation, our projections suggested that the water balance of Lake Kinneret could experience a deficit of 14–40 % this century. We anticipate this substantial projected deficit combined with a considerable growth in population expected for this region could have considerable negative impacts on water availability and would consequently increase regional water stress.

The emperor’s new loaves: Scarcity and abundance in John 6:1–15 and 21:1–14

John 6 and 21 demonstrate moments of both scarcity and abundance. Jesus provides a sign in John 6:1–15, miraculously feeding thousands of followers with five loaves and two fish. In John 21:1–14, Jesus’s simple command to his disciples results in a remarkable catch of fish. Both of these Johannine stories take place along the Sea of Galilee “of Tiberias.” These uniquely Johannine notes about the location foreground the Roman imperial context and political implications in these passages. In spite of rampant food insecurity and scarcity in the empire, Roman ideology insisted that the emperor’s reign brought blessings and abundance to all. In these two scenes on the lake, the Fourth Gospel contests Roman imperial claims of a golden age of prosperity and abundance while setting forth alternative claims about true abundance and life made available through Jesus and his Father.

Freshwater microbial metagenomes sampled across different water body characteristics, space and time in Israel

Freshwater bodies are critical components of terrestrial ecosystems. The microbial communities of freshwater ecosystems are intimately linked water quality. These microbes interact with, utilize and recycle inorganic elements and organic matter. Here, we present three metagenomic sequence datasets (total of 182.9 Gbp) from different freshwater environments in Israel. The first dataset is from diverse freshwater bodies intended for different usages – a nature reserve, irrigation and aquaculture facilities, a tertiary wastewater treatment plant and a desert rainfall reservoir. The second represents a two-year time-series, collected during 2013–2014 at roughly monthly intervals, from a water reservoir connected to an aquaculture facility. The third is from several time-points during the winter and spring of 2015 in Lake Kinneret, including a bloom of the cyanobacterium Microcystis sp. These datasets are accompanied by physical, chemical, and biological measurements at each sampling point. We expect that these metagenomes will facilitate a wide range of comparative studies that seek to illuminate new aspects of freshwater microbial ecosystems and inform future water quality management approaches.