The deep water in the western Mediterranean Sea was found to be significantly affected by a climatic event that took place in the eastern Mediterranean during the 1990s. Numerical simulations of the entire Mediterranean Sea showed that multiple equilibria states in the eastern Mediterranean can exist under present-day-like conditions. The two stable states that were found are associated with intermediate water exchange between the eastern Mediterranean's Aegean and Adriatic Basins. In the first state, the Adriatic acts as a source of deep water that flows into the deep layers of the eastern Mediterranean; in the second state, there is no source of deep water in the Adriatic and the eastern Mediterranean intermediate water is warmer and saltier. We studied the water pathways, in both stable states, into the western Mediterranean and found that the eastern Mediterranean water's properties signature can be seen as far as the Gulf of Lion, which is an important open-ocean deep water convection site. Meaning that, the eastern Mediterranean water characteristics are manifested in deep and intermediate water properties all over the Mediterranean Sea. The water propagating from the eastern to the western Mediterranean also has different flow regimes, in both states, through the Sicily Strait and in the Tyrrhenian Basin, as seen from a Lagrangian analysis.

In Lake Kinneret (the biblical Sea of Galilee), Israel, internal waves of significant amplitude are induced by westerly winds. These waves give rise to upwelling into the surface mixed layer of colder, oxygen‐depleted water from the hypolimnetic and metalimnetic layers. If upwelling occurs soon after the onset of annual thermal stratification, when surface mixed layer extends over a narrow depth range, but the hypolimnion is already anoxic, there is a potential for massive fish kills as fish cannot escape the anoxic water that intrudes into the surface mixed layer along the western shore. This study uses a coupled three‐dimensional atmosphere‐lake model to elucidate the mechanisms behind these infrequent major fish kills in Lake Kinneret. Remarkably, nowadays fish‐kill events happen at the same location in the lake where the biblical Miracle of Loaves and Fishes and presumably the Miraculous Catch of Fish occurred two millennia before the present and may explain the appearance of large numbers of easy‐to‐collect fish close to the shore described in the biblical narratives.

Seasonality in environmental conditions plays a fundamental role in shaping lake ecosystems. However, patterns of seasonality vary worldwide, and these patterns are shifting over time amid global change. Thus, it is increasingly important to evaluate how seasons and seasonality are represented in lake ecosystem research. Here, we used a literature review and global data analysis to synthesize approaches for conceptualizing seasons and seasonality in lakes. We found that a wide range of criteria are used to delineate discrete seasons in published literature, including fixed dates (e.g., months, solstice/equinox), environmental thresholds (e.g., temperature and precipitation cutoffs), and lake‐specific indicators (e.g., ice cover, plankton phenology). Analyzing data from lakes worldwide, we found that using different criteria to define the same season resulted in divergent interpretations of ecosystem states. Based on our synthesis, we offer recommendations for how to incorporate seasonality into lake research and communications amid global change.

In May 2022, a unique dry easterly windstorm generated extreme surface waves on Lake Kinneret, leading to the destruction of the eastern coastal promenade. Wind speeds exceeded 90 km/h in the northern part of the lake and 60 km/h in its eastern part, resulting in significant mixing captured by an in-situ sensor network. Since the lake was already thermally stratified, the atmospheric storm generated a steep-fronted internal surge that propagated along the thermocline. This surge caused intensified mixing, deepened the thermocline, and triggered sediment resuspension as it shoaled over the lake’s slope. To assess the storm's impact on lake mixing and the role of air-sea interactions, we applied a 3D coupled lake-atmosphere model. The study examines the storm-driven internal surge within the context of a pre-existing internal wave field generated by the daily Mediterranean breeze. Our findings suggest that this internal wave field plays a role in modulating the excitation of the internal surge. Furthermore, we analyze the spatiotemporal variability of lake mixing regimes and the interactions between the lake and atmosphere during the May 2022 storm. The results are supported by observations from multiple locations within the lake and simulations conducted with both coupled and uncoupled 3D simulations.

The hydrozoan Craspedacusta sowerbii , native to the Yangtze River system in China, has become an invasive species in freshwater ecosystems worldwide. Multiple genetic lineages have been introduced globally, yet the species’ taxonomic identity remains unresolved. Its life cycle alternates between a benthic polyp stage and a pelagic medusa stage, the latter being the primary focus of most distributional studies. In Israel, the species was previously reported from the Kinneret watershed, though recent records are lacking. Here, we surveyed streams and ponds in the Golan Heights for both medusae and polyps and conducted genetic analyses on collected specimens. Three mtDNA-haplotypes were identified, corresponding to those previously described from European populations. Most sites exhibited homogeneous haplotype composition, suggesting limited admixture and restricted short-distance dispersal. While our survey did not confirm the presence of C. sowerbii in its pelagic stage, the detection of polyps in multiple inflowing streams suggests that colonization of Lake Kinneret is likely. Toward planning a proper monitoring program, we first performed 3D hydrodynamical simulations of the lake dynamics, incorporated with both transport processes, injected from the major inflowing streams. The simulations suggest specific positions for yearly and seasonally coastal ‘hotspots’ of jellyfish distributions. Furthermore, the simulations indicate seasonal variations in the penetration potential of jellyfish into the lake. In winter, they penetrate deeper and away from the coasts, whereas in summer they remain concentrated near the lake surface and close to the coasts.