Morris Kahn Marine Research Station - תחנת מוריס קאהן לחקר הים - Morris Kahn Marine Research Station's Blog
    The 11th MKMRS newsletter is here!

    In this issue: 

    • ECS conference - highlights and review

    • Hello to new staff! Discussing the power plant's capacity reduction

    • Our media manager presents his MSc research

    Click on the image to read more, or go to our Newsletter page

    11th newsletter 1

    Simultaneous observations revealed the non-steady state effects of a tropical storm on the export of particles and inorganic nitrogen through a river-estuary continuum

    JingjieLinab Michael D.Kromcd FenfangWangab PengChengb QibiaoYuab NengwangChenab

    aFujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, College of the Environment and Ecology, Xiamen University, Xiamen, PR China
    bState Key Laboratory of Marine Environment Science, Xiamen University, Xiamen, PR China
    cMorris Kahn Marine Station, Charney School of Marine Sciences, University of Haifa, Haifa, Israel
    dSchool of Earth and Environment, University of Leeds, Leeds, UK


    •During storms, sediments deposited in estuaries during normal flow, are resuspended adding DIN to the extra nitrogen fluxing down the river.
    •Additional nitrate was added to the estuary by leaching from adjacent soils and groundwater, nitrification, and less denitrification.
    •Storms increase total nitrogen flux to coastal areas, with relative more ammonium export during increasing hydrography.



    An important consequence of storms in river-estuary systems is major changes in hydrology and nutrients being fluxed from the land to the coastal ocean. However, the impacts of storms on the nature and amount of dissolved inorganic nitrogen (DIN) in the river-estuary continuum are poorly understood. In this study, two week’s continuous observations on two lower riverine fixed stations and an estuarine fixed station in the Jiulong River (SE China) were carried out during a complete storm event in June 10th to 23rd 2019. Suspended particulate matter (SPM), nitrogen species and their isotopic ratios, nitrifying and denitrifying functional genes were measured. The increased river discharge caused the freshwater-brackish water boundary to move downstream and altered the pattern of particle distribution and the location of the estuarine turbidity maximum. The increased river SPM and inorganic nitrogen was associated with watershed soil erosion, sediment scour and land use. Both in the river and estuary, the peak concentration of ammonium arrived faster than nitrate. Apart from river inputs, there was an additional increase of 40 ± 8% of DIN supplied within the tidal river and estuary. The additional DIN mostly came from resuspended sediments and catchment runoff, while increased nitrate also came from soil and ground waters, increased nitrification and decreased denitrification in the estuary. These results suggest that during baseflow conditions the wetlands in the upper estuary acts as a temporary nutrient trap and biogeochemical incubator, while in storms the transformed pollutant N was fluxed from the river-estuary continuum to the adjacent coastal areas.

    effects of a tropical storm


    Shark autopsy

    The winter aggregation of sharks near the Orot Rabin power plant is largely composed of large, female dusky sharks and smaller, male sandbar sharks. It is, therefore, possible that the female sharks are using the warmer waters of the effluent at some stage of their reproductive cycle. 

    In 2016, a pregnant dusky shark washed ashore near Hadera with 8 mid-stage fetuses in her uterus. Further evidence of pregnant sharks was collected via ultrasonography in 2018, which revealed 3-4 fetuses in the womb of a live dusky shark. The presence of pregnant sharks strongly indicates that mating and nursery grounds may exist along the coastline, and thus a science-based conservation and management plan is a priority for the Apex Marine Predator (AMP).

    However, the hypotheses of mating and birth at Hadera are not considered, as the sharks do not display mating scars, and no observations of parturition have ever been recorded. It is also known that in other regions and species, temperature greatly influences the reproductive physiology of the animals.

    Thus, the long-term increase in seawater temperature (an effect of climate change), as well as the shark's visits to the warm water effluent near Haera stream, make this a very interesting study to undertake. The ultrasound scans are conducted in collaboration with the Tal Raz laboratory of the Hebrew University of Jerusalem, using portable underwater ultrasound.

    This tool, in combination with biochemistry and endocrinology, can produce detailed results on the reproductive stage and condition of the shark and her pups.


    Last year, Dr Shaked Druker of the Tal Raz Laboratory (HUJI) scanned a female shark on-board a tagging expedition. Their lab analyzed the video and concluded that one 15 cm embryo was developing in the uterus (scan image from sonogram below, picture of embryo placed above to assist with viewing the scan).


    shark embryo

    image 3


     Roee Diamant, Dep. of Marine Technologies. Aviad Scheinin, The Morris Kahn Marine Research Station.  University of Haifa.


    • Aquatic animals rely on underwater sound for critical life functions such as localization, communications, foraging, and mating.
    • With the large increase in human marine activity, our seas have become populated with boats and ships projecting underwater radiated noise (URN) of extremely high power that propagates over areas of sometimes 20 square km.
    • The effects of shipping URN on animal’s behavioral include communication disorders; loss of navigation capability; decrease in foraging activity.
    • Current investigations are biased towards physiological impacts and a systematic study for the accumulated effects of shipping URN on the behavioral of aquatic species has not been performed.
    • The main goal of our project is to quantify the impacts of shipping disturbance to the behavioral of Bottlenose dolphin (Tursiops truncatus).

    • This species occurs in almost all tropical and temperate regions and can be found in both coastal and offshore waters.
    • Their large range of distribution makes them ideal representatives in this study as they show plasticity in habitat choices and can migrate to another environment in case of a strong disturbance like sound.
    • Dolphin's vocalization was shown to serve as a proxy for behavioral implications. For example, no clicks and many whistles are characteristic of social behavior, while low frequency clicks typically indicate navigation or traveling and high frequency is indicative of foraging activity. However, statistical comparison of passive acoustic recordings and shipping URNs has never been explored, and thus the specific characteristics in the dolphin’s vocalization reflecting behavioral changes were not determined.
    • Considering this, in our project we compare between dolphin whistles emitted in and without the presence of vessels. These will include the signal’s duration, bandwidth, maximum and minimum frequency, curving up, curving down, symmetrical shape characteristics, and variance of signal strength across the bandwidth.
    • This pilot project was done near the dolphin Reef in Eilat having 4 bottlenose dolphins in the facility.
    • Four hydrophones were set on the bottom nearby simultaneously sampled at 96kHz and recording continuously for a month. Two one-month deployments took place.
    • The analysis focused on 3 elements:
    1. Detection and characterization of dolphins’ emissions (expected detection distance is 500m).
    2. Detection and characterization of nearby vessels (expected detection distance is 5km).
    3. Comparison of features in the dolphins’ vocalization according to existence of vessels.

    The results shows that the dolphins change their whistles production in the presence of vessels noise. 


      First seasonal high sensitivity nutrients in the Pelagic Eastern Mediterranean.Excess Nitrate during winter mixing decreasing to Nutrient depleted in late stratified season.
      Phosphate depleted entire year with low DOP (40-30 nM) in photic zone.
      The measured N:P ratio depends on seasonality and not just location.
      Calculated Export Production and other biogeochemical properties confirm EMS behaves like a P depleted ocean gyre.



    The Eastern Mediterranean Sea (EMS), is ultra-oligotrophic with unusual anti-estuarine circulation. It is P depleted and the limited enrichment studies which have been carried out, suggest seasonal changes in nutrient limitation. In this study high sensitivity dissolved nutrients (and associated parameters) were determined monthly over an annual cycle at a pelagic location in the SE Levantine basin. Nitrate & Nitrite (Nox) concentrations were high (300–500 nM) during the winter mixing period and enabled a concurrent phytoplankton increase in which larger picoeukaryotes and eukaryotes were dominant. After the thermal stratification of the water column commenced, Nox decreased through early summer transition period to low values (generally 50 nM or less) in the late summer. DIP remained at low nM concentrations the entire year while DOP decreased from 40 nM in winter to 30 nM in summer.. Prochlorococcus, the smallest picocyanobacteria, that does not typically utilize nitrate, dominated during the summer when both Nox and DIP concentrations were lowest. Ammonium concentrations were low (10–100 nM) with no systematic changes with season or depth. As a result, the DIN:DIP ratios were high (20–825) in winter and low (2–66) in summer, showing that these ratios vary seasonally. The dynamics of nutrient availability combined with the temporal changes in total chlorophyll and the altered dominance of the predominant phytoplankton species (i.e. nitrate-metabolizing Synechococcus during winter versus the smaller Prochlorococcus abundant in summer), leads to our hypothesis that the seasonal change in DIN:DIP indicates a switch from P limitation in winter during the annual phytoplankton increase to N&P or even N limitation in summer. Export Production (172 mmol N m−2 y−1) determined from the calculated loss of Nox from the photic zone, was similar to previous estimates in the EMS. Our results in terms of seasonally changing nutrient dynamics and resulting productivity confirm that the EMS has many of the characteristics found in P starved ocean gyre systems.

    Model figure1

    nutrients TH2

    Published! The calcifying interface in a stony coral primary polyp: An interplay between seawater and an extracellular calcifying space

    Coral reefs are the most biodiverse marine ecosystems on the globe. In addition to breathtaking beauty, they have significant evolutionary and financial importance. Unfortunately, today, coral reefs face significant threats due to global climate change and other stressors of anthropogenic origin. Stony coral skeletons construct the structural foundation of the coral reef ecosystem. The biomineralization process (Mineral production by a live organism), by which stony coral build their skeleton, is essential for the thrive and sustainability of coral reef ecosystems. So how come it is still uncovered?
    One of the reasons is that coral biomineralization is a slow process that spans from the macroscopic to the sub-cellular scale. Another reason is that stony corals are hard to culture and reproduce in the lab. In Prof. Tali Mass Lab, at the Morris Kahn Marine Research Station, Sdot Yam, this biomineralization process is being studied using cutting-edge experimental techniques. In a new article published in the Journal of Structural Biology, Dr. Gal Mor Khalifa, Dr. Shani Levy, and Prof. Tali Mass followed biomineralization pathways in young stony coral recruits of the indo-pacific species Stylophora pistillata. Young corals establish new colonies and are therefore a critical life stage in the development and prosperity of the reef. The study shows that young coral tissues are much more permeable to the external seawater than previously estimated. This tissue permeability facilitates the incorporation of large volumes of seawater into the mineralization site. This characteristic may make young corals more vulnerable than their adult counterparts to ocean acidification and to microplastic, suspended sediments, and other seawater contamination, which may be incorporated into their body along with the seawater. These findings should be taken into account in coral reef risk assessment and management along the Israeli Red Sea coast and in coral reed ecosystems around the globe.
    The calcifying interface in a stony coral primary polyp: An interplay between seawater and an extracellular calcifying space


    Stony coral exoskeletons build the foundation for the most biologically diverse marine ecosystems on Earth, coral reefs, which face major threats due to many anthropogenic–related stressors. Therefore, understanding coral biomineralization mechanisms is crucial for coral reef management in the coming decades and for using coral skeletons in geochemical studies. This study combines in–vivo imaging with cryo-electron microscopy and cryo–elemental mapping to gain novel insights into the biological microenvironment and the ion pathways that facilitate biomineralization in primary polyps of the stony coral Stylophora pistillata. We document increased tissue permeability in the primary polyp and a highly dispersed cell packing in the tissue directly responsible for producing the coral skeleton. This tissue arrangement may facilitate the intimate involvement of seawater at the mineralization site, also documented here. We further observe an extensive filopodial network containing carbon-rich vesicles extruding from some of the calicoblastic cells. Single-cell RNA-Sequencing data interrogation supports these morphological observations by showing higher expression of genes involved in filopodia and vesicle structure and function in the calicoblastic cells. These observations provide a new conceptual framework for resolving the ion pathway from the external seawater to the tissue-mineral interface in stony coral biomineralization processes.

    The calcifying interface in a stony coral primary polyp: An interplay between seawater and an extracellular calcifying space

    Selection of mesophotic habitats by Oculina patagonica in the Eastern Mediterranean Sea following global warming

    The tempered coral Oculina patagonica that live in the Mediterranean Sea uses photosynthesis and predation as its food sources. This coral can be found in the western Mediterranean as well in the eastern Mediterranean, but, until recently it was found only in the shallow water of less than 10m. The water temperatures in the Mediterranean increase from west to east while the temperatures in the west Mediterranean range between 14-240c in the eastern Mediterranean the temperature range between 16-310c. Global warming increased the water temperature in the eastern Mediterranean by 30c in the past three decades. That increase brought the coral Oculina patagonica to its maximum temperature tolerance. Recently we discovered that this coral can also be found in the eastern Mediterranean at 30m depth. The water temperature at that depth is cooler by two degrees in the summertime. We think that the coral has migrated to this depth to avoid the heat stress of the shallow water of the eastern Mediterranean Sea. We checked what adaptation it required from the coral and tested some physiological and nutritional aspects. We did not find differences between the shallow and deep coral colonies Physiology. Their nutrition is the same and they acquire the same proportion of energy from predation and photosynthesis. In contrast to the western Mediterranean where the coral lives in the shallow water exposed to the sun in the eastern Mediterranean in the shallow water, they live in a low light area. We think that this fact facilitated their movement to the deeper water where the light intensity is lower but the coral grows exposed to the light. Therefore, coral in the eastern Mediterranean shallow and deep water gets the same amount of light at both depths.

    X-ray Spectroscopic Quantification of Phosphorus Transformation in Saharan Dust during Trans-Atlantic Dust Transport


    Saharan dust is an important phosphorus (P) supply to remote and oligotrophic parts of the oceans and American lowland tropical rainforests. Phosphorus speciation in aeolian dust ultimately controls the release and bioavailability of P after dust deposition, but the speciation in Saharan dust and its change during the trans-Atlantic transport remains unclear. Using P K-edge X-ray absorption near edge structure (XANES) spectroscopy, we showed that with increasing dust traveling distance from the Sahara Desert to Cape Verde and to Puerto Rico, about 570 and 4000 km, respectively, the proportion of Ca-bound P (Ca-P), including both apatite and non-apatite forms, decreased from 68–73% to 50–71% and to 21–37%. The changes were accompanied by increased iron/aluminum-bound P proportion from 14–25% to 23–46% and to 44–73%, correspondingly. Laboratory simulation experiments suggest that the changes in P speciation can be ascribed to increasing degrees of particle sorting and atmospheric acidification during dust transport. The presence of relatively soluble non-apatite Ca-P in the Cape Verde dust but not in the Puerto Rico dust is consistent with the higher P water solubility of the former than the latter. Our findings provide insights into the controls of atmospheric processes on P speciation, solubility, and stability in Saharan dust.



    The COST Action SEAWHEAT is kicking off today in a virtual setting with the administrators in Brussels, and the Management Committee chose over the past few months. The network is titled: 
    The innovative network has come to fruition through a lot of hard work by Professor Muki Shpigel and Dr Leigh Livne of MKMRS - it can be best described numerically!
    1. 2 (plus!) years of planning and writing
    2. 86 collaborators across Europe and abroad
    3. 2 submissions
    4. 1 rejection!
    5. 4 years of grant funding
    We wish you the best of luck!
    image 1
    Speed FluorIS

    New article published!

    Coral recruitment represents a key element for coral reef persistence and resilience in the face of environmental disturbances. Studying coral recruitment patterns is fundamental for assessing reef health and implementing appropriate management strategies in an era of climate change. The FluorIS system has been developed to acquire high resolution, wide field-of-view (FOV) in situ images of coral recruits fluorescence and has proven successful in shallow reef environments. However, up to now, its applicability to mesophotic coral ecosystems remains unknown due to the complexity of the system and the limited time available when working at mesophotic depth. In this study we optimized the FluorIS system by utilizing a single infrared-converted camera instead of the bulkier regular dual-camera system, substantially reducing the system complexity and significantly decreasing the acquisition time to an average of 10 s for a set of 3 images. Moreover, the speed-FluorIS system is much more economical, decreasing the cost of the full set-up by roughly 40% compared to the original dual-camera system. We tested the utility of the speed-FluorIS by surveying coral recruits across shallow and mesophotic reefs of the Red Sea (Gulf of Eilat) and Bermuda, two of the most northerly reefs in the world with markedly different substrate and topography, and demonstrate that the modified system enables fast imaging of fluorescence to study coral recruitment patterns over a broader range of depths and reef topographies than previous fluorescence methods. Our single-camera system represents a valuable, non-invasive and rapid underwater tool which will help standardize surveys and long-term monitoring of coral recruits, contributing to our understanding of these vital and delicate early life stages of corals.


    ICF comp for article




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