Knowledge atlas Science

Neven Cukrov, Ph.D., Oceanology

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Our planet is strongly influenced by human activities, so we have called this era the Anthropocene. Some of the most important threats are environmental pollution and dramatic biological diversity loss. All this is strongly reflected on the sea and oceans, and protecting these largest ecosystems on earth is equal to protecting the planet.

Name of Field in the local language
Oceanologija
Area of Expertise
Biogeochemistry of water systems
Scientists / Scientific team
Neven Cukrov, Ph.D.
Location, Institution, Website
Ruđer Bošković Institute, Division for Marine and Environmental Research, Martinska, 22000 Šibenik, Croatia Link to website
Contact
+385 98 708174
Type of Institution
Scientific Research Institute
Years of Active working in the Field
25

Laboratory and research space
Marine station Martinska; boat ‘Šibenik 800’ (for 12 people and 2 tons of cargo); laboratory at the Ruđer Bošković Institute
Materials and equipment
Underwater cameras, ROVs (Remotely operated underwater vehicles), video surveillance cameras, video imaging motion detection software, data loggers
Research Methods / Processes
Sampling, monitoring (metrology, water and air quality, biodiversity, noise), measuring concentrations of different matters in the sea, animal species counting

Most impactful project
Biodiversity monitoring within the Croatian Nature 2000 coastal site, 'Ušće Krke' (Site code: HR3000171)

The Adriatic is a small sea, so human influences are more pronounced.

Neven Cukrov is a senior scientist at the Division for Marine and Environmental Research, at the Ruđer Bošković Institute in Zagreb, Currently, he serves as the head of the Marine station Martinska near Šibenik. Alongside his research duties, he is a full-time lecturer at the undergraduate and graduate levels at the University of Zadar, holding the title of associate professor. He is also involved in doctoral studies in oceanology at the University of Zagreb. His research field encompasses the anthropogenic impact on the aquatic environment through the investigation of biogeochemical processes within it. conducts research on the distribution of trace metals, natural and artificial radionuclides, and microplastics within water systems. Additionally, he focuses on developing representative sediment sampling techniques and conducting sampling in speleological environments. His research area also encompasses water systems, including underground systems in karst regions where coastal aquifers intersect with seawater, forming underground estuaries and numerous submerged groundwater discharges (vrulje).

Neven Cukrov is a senior scientist at the Division for Marine and Environmental Research, at the Ruđer Bošković Institute in Zagreb, Currently, he serves as the head of the Marine station Martinska near Šibenik. Alongside his research duties, he is a full-time lecturer at the undergraduate and graduate levels at the University of Zadar, holding the title of associate professor. He is also involved in doctoral studies in oceanology at the University of Zagreb. His research field encompasses the anthropogenic impact on the aquatic environment through the investigation of biogeochemical processes within it. conducts research on the distribution of trace metals, natural and artificial radionuclides, and microplastics within water systems. Additionally, he focuses on developing representative sediment sampling techniques and conducting sampling in speleological environments. His research area also encompasses water systems, including underground systems in karst regions where coastal aquifers intersect with seawater, forming underground estuaries and numerous submerged groundwater discharges (vrulje).

The Marine Station Martinska, located near the city of Šibenik, occupies a strategic position at the confluence of the Krka River estuary and the Adriatic Sea, where freshwater meets seawater. Equipped with state-of-the-art tools, the station facilitates the measurement of various physicochemical parameters within water systems and facilitates the collection of samples from water, sediment, and biota for subsequent analysis in the laboratory.

In their exploration of the estuary and coastal sea, researchers utilize the boat ‘Šibenik 800’, measuring 9.3 meters in length and powered by an internal diesel engine boasting 242 kW. This propulsion enables the vessel to achieve a maximum speed of 32 knots, with a comfortable cruising speed of approximately 20 knots. With storage tanks capable of holding 400 liters of fuel and 200 liters of drinking water, the boat is certified to accommodate 12 individuals and transport up to 2 tons of cargo. At the Marine Station, essential measurements encompass the concentrations of nutrients, organic matter, chlorophyll, and microplastics. While basic analyses are conducted on-site, more intricate procedures necessitate sample preparation before analysis at the Institute in Zagreb. Scientists at the station are experienced in field work and most of them have completed advanced scuba diving and speleological courses.

Part of the work includes constant monitoring of the state of the environment, which includes metrology, water and air quality, biodiversity monitoring with underwater cameras and ROVs, noise monitoring and especially underwater noise monitoring. At the Marine station, experimental fish and mussel farming began 50 years ago, so even today part of the work includes supporting the operation of numerous shellfish and fish farms in the estuary itself and its immediate and distant surroundings. However, the primary focus remains on interdisciplinary research of the aquatic environment, carried out by a dedicated team of a dozen scientists and students permanently stationed at the Marine Station.

Biodiversity monitoring within the Croatian Nature 2000 coastal site, ‘Ušće Krke’ (Site code: HR3000171), employs video-based surveillance techniques. Positioned at a depth of 5 meters in the Krka River Estuary, directly in front of the Marine Station, a surveillance camera encased for underwater use captures footage. The camera is tethered via a 50-meter underwater cable. Concurrently, data loggers at depths of 2.5 and 5 meters continuously gather temperature, tide, and salinity data. To facilitate species counting, motion detection software tailored for video imaging was developed and implemented. All captured images undergo visual examination and verification. Moreover, live underwater video feeds are accessible to the public via online streaming platforms, fostering engagement and awareness among interested stakeholders.

Microplastics have been recognized as a global anthropogenic contaminant in aquatic ecosystems. Owing to their durability, they remain in the environment over extended periods, during which they can undergo translocation via winds or currents, altering their distribution within the water column. Furthermore, microplastics are prone to adsorption of toxic pollutants and biofouling that leads to changes in initial water density and affects buoyancy. Despite the extensive and rapidly growing research on microplastics in oceans and coastal seas, little information exists on microplastic distribution through the salinity gradient. The scientists study microplastic distribution through the salinity gradient of a highly stratified estuary.

Nautical tourism provides stress to the environment by discharging effluents in the sea, emitting air pollutants, and interfering with marine organisms and their habitats. While some environmental aspects of nautical tourism, such as discharging effluents, chemicals or waste, emitting air pollutants, and interference with marine organisms and their habitats, are subject to partial regulation, others remain under-researched. Typical example of the latter is the emission level of pollutants from antifouling paints, particularly copper (Cu), which is the focus of scientific research. The estuary is a popular nautical destination with easy access to the Krka National Park and attractive coastal and estuary landscapes. It is annually visited by more than 1 million people. Notably, concentrations of copper in surface water during the summer months spike to levels up to 20 times higher than those observed during winter, underscoring the need for comprehensive research and management strategies to address the environmental impacts of nautical tourism.

Anchialine caves have been the subject of increasing research in recent years due to their interesting aquatic environment, which combines the characteristics of a subterranean estuary (stratified water body) and a deep ocean (lack of light and oxygen, chemosynthesis, slow water exchange). In Croatia, along the Adriatic coast and on the islands, almost one hundred and fifty anchialine speleological objects are known, of which only a few have been partially explored. Due to the freshwater surface layer, many of them served as a source of drinking water throughout history, which is why archaeological finds have often been discovered near them. In the last 15 years, preliminary exploration of 7 anchialine speleological objects (’Špilja pod Orljakom”, ’Špilja Čapljina’ also known as a Sarcophagus cave, ’Vodena jama na Srimi’, ’Izvor Litno’, ’Špilja u uvali Vidrovača’, ’Bićinska pećina’, ’Špilja Mandalina’) have been carried out along the estuary of the Krka River.