The Institute for Water ‘Josip Juraj Strossmayer’, in partnership with SeaCras, has developed a new system that combines satellite observations with field measurements to support more comprehensive, next-gen water body monitoring. More precisely, the monitoring of inland, coastal waters as well as the open sea.
The approach makes it possible to monitor a large number of water bodies at the same time, from large and small rivers to lakes, water reservoirs, fish ponds and accumulation lakes, coastal areas and seas. By connecting remote sensing data with traditional field monitoring, the system can evaluate biochemical and physical parameters defined by Water Framework Directive (WFD) and Marine Strategy Framework Directives (MSFD). Also, the system helps to detect rapid changes of water quality earlier and provide a clearer picture of how aquatic ecosystems respond to environmental pressures and protection measures. Especially important aspect is cross-border monitoring to assess what migrates to Croatian waters from upstream in the Danube river system, as well as from territorial waters of neighbouring countries at the Adriatic sea.
Just under a year ago, we signed a cooperation agreement with the Josip Juraj Strossmayer Water Institute. Today, partners are introducing a new generation of satellite-based monitoring for the condition of dynamic and stationary water bodies by cutting-edge technology, which puts Croatia in the top performing countries.
By monitoring the quality of riverine systems and streams in Croatia, SeaCras is able to record human impacts within the national territory, as well as transboundary influences that may affect water conditions upstream and downstream. This allows for the first time to evaluate the effect of the river system on its endpoints – seas and lakes.
Similar technologies are already being applied in several European countries, including Germany, Finland and Sweden. Through this cooperation, we have launched an advanced water monitoring technology we can be proud of — a best-in-class solution developed through domestic expertise and production.
From the Drava River to Broader Water Monitoring
The first demonstration was carried out on the Drava River, following the launch of one of Croatia’s largest wastewater treatment plants. According to the Water Institute, the comparison of conditions before and after the facility began operating showed early signs of improvement in water quality, while satellite observations confirmed the findings gathered through field monitoring.
The analysis recorded changes in several indicators used to assess ecological pressure and eutrophication in river ecosystems, which refers to excessive nutrient enrichment, mainly from nitrogen and phosphorus compounds, which in turn causes algal blooms. These parameters are important for understanding how nutrients and other pressures affect aquatic environments, particularly in relation to algal growth and overall ecosystem balance.
High spatial resolution also enables the system to go beyond major rivers and lakes. It opens the possibility of monitoring smaller waterways as well, supporting more detailed assessments at local, national and cross-border levels.
Satellite view of the distribution of chlorophyll-a concentrations in the Drava River near Belišće, produced in collaboration between the Josip Juraj Strossmayer Water Institute and SeaCras.
Better Data for More Confident Decisions
For water management, this marks an important shift. Investments in environmental protection can be assessed not only through the infrastructure built, but also through measurable changes in the environment itself. By combining satellite data and field measurements, decision-makers can better understand what is happening in the water after interventions are made.
The same approach has strong potential for wider use across the Adriatic and other coastal areas, which has already proven to be successful in coastal areas such as Zavrtnica and Jablanac. It can support the monitoring of coastal urbanisation, wastewater treatment impacts, river inflows, climate-related pressures and individual events that leave visible traces in water or the sea.
For SeaCras, the collaboration reflects the growing role of satellite-based intelligence in protecting water ecosystems. By turning complex environmental data into practical information, the system can support earlier detection, stronger evidence and more informed decisions for the sustainable management of rivers, lakes, coastal areas and seas.
SeaCras presented the final results of our Coastal Intelligence study at the VI. meeting of the Pakleni Island Committee in Hvar, where representatives, institutions, and local stakeholders gathered to discuss the growing pressure of nautical tourism on one of Croatia’s most valuable island areas.
Presented by Josip Karadža and Robert Šulc, the study focused on maritime activity in the Pakleni Islands archipelago, using SeaCras’ AI-enabled Coastal Intelligence operational centre to map vessel presence, anchoring patterns, and areas of increased environmental pressure of nautical tourism across the 2023 and 2025 seasons.
The findings confirm what many coastal communities are increasingly experiencing: nautical tourism is growing, but without high-quality monitoring and actionable data, its impact can remain difficult to measure, manage, and respond to in time.
From Vessel Detection to Smarter Coastal Protection
According to the analysis, vessels were recorded across the entire archipelago, with the highest concentration in the bays of Vinogradišće, Palmižana, and Ždrilca. During peak season, between 10:00 and 12:00, up to 500 vessels were recorded in the waters of the Pakleni Islands, while total daily numbers were even higher.
The study also revealed clearbehavioural patterns. Around 50% of vessels used anchoring, while approximately 30% were tied to the shore, mostly smaller vessels up to 12 metres in length. The most common vessels were between 10 and 16 metres long, representing 43% of recorded boats. Vessels under 10 metres accounted for 37%, those between 16 and 24 metres for 13%, while vessels over 24 metres represented 7%.
Satellite-based vessel detection around Hvar and the Pakleni Islands, showing concentrated nautical activity across the monitored coastal area.
One of the most concerning findings was that 57% of vessels were anchored above strictly protected Posidonia oceanica habitats, especially in the areas of Soline, Prevojice, and Ždrilca. Posidonia meadows are among the most important marine ecosystems in the Mediterranean, playing a key role in biodiversity protection, seabed stability, water quality, and carbon storage.
The analysis also identified cases of large vessels being moored to trees and nearby coastal vegetation, creating additional pressure not only on the seabed but also on the fragile coastal landscape.p
For SeaCras, this study demonstrates the practical value of Coastal Intelligence: transforming satellite data, AI analysis, and maritime monitoring into clear insights that can support decision-making, conservation planning, and more responsible destination management.
Encouragingly, the public institution ‘More i Krš’, together with local authorities, is already working to turn these findings into concrete action aimed at protecting the Pakleni Islands and preserving their long-term ecological value.
As pressure of nautical tourism on coastal and marine areas continues to increase, especially in high-demand nautical destinations, data-driven monitoring is becoming essential. With solutions such as SeaCras’ Coastal Intelligence, ports, coastal communities, public institutions, and tourism stakeholders can better understand what is happening at sea — and act before environmental pressure turns into lasting damage.
Thousands of oil spills have been recorded over the years, releasing large volumes of oil into marine ecosystems and causing lasting damage to biodiversity, fisheries, tourism and coastal economies. While major incidents attract attention, smaller fuel leakages and uncontrolled discharges, including diesel and similar pollutants, can be just as harmful when they go unnoticed.
At the same time, although facing fragile growth, rising costs and uncertainty, maritime transport remains central to global trade, making reliable monitoring and early detection more important than ever. As shipping activity continues to shape global commerce, improving the speed and accuracy of marine pollution detection is becoming an increasingly urgent priority.
It also reinforces the importance of frameworks such as the MARPOL Convention, which set the global standard for preventing pollution from ships.
Figure 1.Left: raw satellite image of the Odessa region, Ukraine. Middle: Coastal Intelligence operational interface output. Right: detected oil spill extent (red) on top of the river plume (green) — output for the client.
Why Fuel Spills Still Go Undetected
One of the biggest challenges is to detect not crude oil, but more volatile oil derivatives and fuel spill and leakage detection.
Moreover, not every suspicious patch on the sea surface equals pollution. Remote sensing operators must distinguish real discharges from naturally occurring phenomena that can look very similar in satellite imagery. These include biogenic slicks, low-wind areas, rainfall zones, internal waves and the leeward sides of islands.
That is exactly where advanced analytics becomes essential. SeaCras developed Coastal Intelligence, a tool that detects fuel spills with the combination of synthetic aperture radar and optical sensors, and different spatial resolutions of sensors. Coastal Intelligence utilises a series of additional atmospheric and marine data (often called auxiliary data) on a data fusion principle. This is a new methodology of deep learning that increases precision and detection rate of pollution incidents by reducing false positives in complex coastal environments.
Figure 2.Satellite-derived view of the incident in Hvar coastal region, showing the detected thin diesel leakage pollution intensity over the affected area, with warmer colors indicating higher surface concentrations of oil derivatives and the red outline marking the highlighted area of high pollution intensity area.
How Coastal Intelligence Improves Marine Pollution Monitoring
Coastal Intelligencecombines proprietary satellite imagery processing modules with an innovative data analysis approach to deliver more accurate results. The system achieves the best known commercial spill detection success rate, including for patches measuring only a few hundred square metres. By using different satellite technologies and different sources, SeaCras delivers operational services more frequently.
Our platform uses high- and very-high-resolution optical satellite data, enabling more precise monitoring even in smaller areas such as ports and marinas.
But its value goes beyond identifying oil-derived pollution. Coastal Intelligence also helps users distinguish between manmade pollution events, uncontrolled sewage discharges near port areas, and natural phenomena such as algal blooms. By combining satellite-derived water quality parameters, satellite images, and sea current vector field maps, the project’s partners have strengthened both their detection and identification capabilities.
This makes Coastal Intelligence especially relevant as a complementary solution to the European Maritime Safety Agency’s CleanSeaNet service, which supports participating states with satellite-based oil spill and vessel detection across Europe.
Figure 3.Satellite-derived view of the diesel spill in Baniyas coastal region, Syria. Left: very high spatial resolution analysis of the oil pollution showing the thin areas and small patches of pollution migration. Right: regional view of the catastrophe, showing the higher pollution levels depicted by warmer colors.
A Scalable Solution for Ports and Maritime Authorities
SeaCras has translated this scientific excellence and technical capability into a commercially available operational service. Today, Coastal Intelligence serves port operators and maritime authorities across the globe, which is an immense achievement, considering it was developed initially only for the Adriatic and Ionian regions.
Its added value lies in wide-area coverage, frequent and affordable monitoring as well as alert-based response support.
In practice, that means giving ports, authorities and coastal stakeholders a stronger chance to detect pollution early, respond faster and better protect the seas they depend on.
Other Marine Pollution Hazards and Unexpected Natural Events
Oil and fuel pollution are just a tip of the iceberg of a much broader range of marine and maritime threats. Floating marine litter, plastic pollution are some of the world’s largest problems, while climate change and warming of our oceans increase the occurrences of harmful and abnormal algal blooms.
Check out how Coastal Intelligence tackles those cases as well!
Figure 1. Example outputs of SeaCras’ vessel monitoring analytics in the Badija area. Left: Vessel detection and classification, showing anchored vessels, vessels moored to coastal infrastructure, and vessels in migration, with an inset of vessel-level attributes. Right: Detection of vessels moored along coastal infrastructure, with mooring length, total detected vessels, and estimated capacity occupancy.
Availability of anchoring or boat mooring spots, especially on remote islands
Environmental protection (MARPOL)
Navigation and Collision Avoidance (COLREGs)
While navigation and collision avoidance rules are something that skippers and boat owners generally abide by, the availability of anchoring or boat mooring spots, lack of established marine analytics, and environmental protection in general are sadly neglected.
1) Availability of Anchoring or Boat Mooring Spots, Especially on Remote Islands
Benthic Protection: Rules often prohibit anchoring in areas with sensitive seagrass (like Posidonia oceanica in the Mediterranean). Dropping a heavy anchor and chain can “scour” the seabed, destroying carbon-sequestering habitats.
Designated Mooring Zones: To prevent ecological damage, many coastal countries now require vessels to use “eco-friendly” permanent mooring buoys instead of dropping their own anchors.
The skipper is legally responsible for ensuring the anchor holds. If your anchor “drags” and you hit another boat, you are generally liable for the damages because you failed to maintain a proper anchor watch or failed to use sufficient scope (the ratio of chain length to water depth).
The WWF study on the Mediterranean published data suggesting that 179,000 vessels may have anchored on seagrass in 2024, 45% of them larger than 24 meters. The study which was based only on Automatic Identification System (AIS) data suggested a huge impact on protected environmental areas covered with seagrass Posidonia oceanica.
Figure 2. Maritime operation detection covered by satellite detection in an area located between Kornati National Park and the island of Žirje, in close proximity to a protected area hosting several sensitive species.
Measuring Environmental Impact
On the other hand, company SeaCras as a contractor to environmental agencies in 2023 identified over 150,000 vessels performing illegal anchoring over Posidonia oceanica meadows only on a small part of the Adriatic sea coastline. In 2025, the number increased by approximately 12%. Locations in Šibenik-Knin county, Split Dalmatia County, and Natura 2000 sites in Dubrovnik-Neretva County were subject to the study. Vessel fleet detected showed that the majority of vessel sizes were under 16m, which makes them invisible to AIS.
Figure 3. Vessel detection and size segmentation covered by satellite detection in an area located between Kornati National Park and the island of Žirje, in close proximity to a protected area hosting several sensitive species.
The scaling factor suggests that there are over 400 000 annual illegal vessel activities of anchoring over protected areas or using pristine nature instead of dedicated and specialised infrastructure only in Croatia’s coastline. The danger to benthic species and habitats is real and mechanical destruction by anchors is alarming. SeaCras’ calculation on the Mediterranean surpasses 1 million illegal anchoring of vessels of all sizes, annually. That’s right, 1 million.
Moreover, this means that governmental agencies are completely blind to more than 90% of maritime traffic, with nautical tourism forming a significant part of it.
This raises additional questions, such as: to what extent marine pollution occurs, based on MARPOL pollution definitions.
2) Environmental Protection (MARPOL)
International Convention for the Prevention of Pollution from Ships(MARPOL) is an international treaty adopted by the International Maritime Organisation to prevent and minimise pollution of the marine environment from ships due to operational or accidental causes.
Figure 4. MARPOL treaty with its six annexes. Source: International Maritime Organisation.
Oil Pollution (Annex I): Discharge of oil or oily mixtures into the sea is strictly prohibited. Even small bilge leaks can lead to heavy fines.
Garbage (Annex V): It is illegal to discharge any plastics into the sea. Food waste can only be discharged under specific conditions (usually more than 12 nautical miles from land).
Sewage (Annex IV): In many territorial waters (and specifically in “No Discharge Zones”), holding tanks must be used and emptied only at designated pump-out stations or beyond the 12-mile limit. Blackwater tanks are big problems for pollution hazards with intestinal enterococci and E. Coli diseases when released in smaller and shallower bays in vicinity of swimmers.
Another, less pronounced negative effect is invasive species expansion.
Figure 5. Direction of sea vessels and maritime safety covered by satellite detection in an area located between Kornati NP and the island of Žirje, in close proximity to a protected area hosting several sensitive species.
Under the international Rules of the Road, an anchored vessel has specific obligations because it is considered “restricted in its ability to maneuver” compared to a vessel under way:
Obstruction of Fairways: It is strictly prohibited to anchor in narrow channels or fairways where you might obstruct the passage of other vessels.
Day Shapes and Lights: You must display a black ball (day shape) or a single all-around white light at night to signal to other mariners that you are not moving.
Aground vs. Anchored: There are distinct rules for a boat that is intentionally anchored versus one that has run aground; the latter requires additional signaling (two red lights at night).
But can nautical tourism actually be sustainable? And how can data help us achieve that?
So What Can We Do to Continue Enjoying Nautical Tourism, but Minimise Our Adverse Effects?
Maritime operations — including nautical tourism, leisure activities, passenger vessels, and fishing boats — generate significant greenhouse gas emissions. Advanced marine analytics allow precise measurement of these emissions by region, specific locations, and across seasonal, annual, and multi-year periods.
These tools also enable accurate evaluation of newly regulated pollutants, such as underwater noise, which impacts fish and marine mammals such as dolphins and whales in different ways. Changes in animal behaviour caused by noise can threaten fragile marine ecosystems.
These effects are particularly evident in narrow channels and bays along the Adriatic coastline, as well as in the pristine crystalline seas of Greece, Indonesia, Thailand, and other sensitive marine environments.
Predictive analytics can forecast areas of dense maritime traffic, helping reduce the risk of collisions and ensuring safer journeys. This also improves nautical tourism passenger satisfaction, reduces costs for early responders and coast guards, and contributes to more effective management of maritime destinations.
Now is the time to turn insight into action — embrace marine analytics to safeguard our oceans, elevate maritime safety, and shape a smarter, cleaner future at sea.
Island trash in Bosnian Drina accumulates once again. Almost each winter, the Drina River develops a dramatic, floating accumulation of plastic and mixed municipal waste that gets trapped near hydropower infrastructure, most notably by barriers in the Višegrad area in eastern Bosnia and Herzegovina.
The Drina River is located in the Balkan region of Southeast Europe. It flows along much of the border between Bosnia and Herzegovina and Serbia before continuing northward to join the Danube River, into which it ultimately flows.
This is not a one-off incident. The phenomenon has been recurring for years, with documented major accumulations in 2020, 2023, 2024, and again during subsequent winter high-flow seasons.
Why does this keep happening?
The core drivers are consistent across reporting and field accounts:
Upstream mismanaged waste: illegal dumps and poorly regulated landfills sit close to riverbanks and tributaries across the wider Drina basin in the Balkan region (including parts of Bosnia and Herzegovina, Serbia, and Montenegro).
Seasonal hydrology: During heavy rain/snowmelt, waste is mobilized into the river network. So winter storms, swollen rivers, and melt events make “collection pulses” more likely.
Hydropower “capture effect”: The reservoir backwater zone creates a hydraulic bottleneck, allowing buoyant materials to accumulate and form dense surface mats.
But not all waste originates on the Drina itself. One particularly important contributor is the Lim River, a major tributary that transports significant debris loads into the Drina system.The basin is hydrologically connected, so upstream failures propagate downstream.
The result: a moving pollution stream becomes a stationary floating landfill.
What satellite imagery reveals and why do we NEED it?
Using multi- and hyperspectral satellite data, floating waste becomes detectable due to:
High reflectance in multiple bands
Surface texture anomalies compared to open water
Persistent spatial clustering at hydraulic convergence zones
Calculation of volume of plastic
Calculation of changes over time
Time-series analysis can show rapid growth following high-discharge events, quasi-stationary persistence once trapped at a barrier, and gradual reduction after mechanical removal or flushing.
This shows how using satellite imagery can help predict, plan, and react in order to prevent this accumulation.
This allows objective monitoring of:
Surface extent (area estimation)
Volume and the mass estimate of garbage island
Duration of accumulation
Growth rates following storm events
Cleanup effectiveness over time
But why does the accumulation present an issue?
The consequences extend far beyond visual pollution. Large-scale debris accumulation affects aquatic ecosystems by altering surface light penetration and oxygen exchange, potentially disrupting habitats and food webs.
It raises concerns about drinking water safety downstream, particularly where untreated or partially treated waste enters the river system. The economic implications are equally significant, impacting tourism, regional reputation, and even hydropower operations when debris interferes with infrastructure.
There are also broader public health considerations linked to contaminated water and unmanaged waste. More importantly, this recurring crisis underscores the need for basin-level governance rather than reactive, site-specific cleanup efforts.
Can we change the future for the better?
Satellite monitoring and other types of remote sensing technology do not and never will replace local action, but it provides transparent and repeatable evidence that shifts the discussion from anecdotal reporting to measurable impact assessment. As rivers often run from several countries, monitoring of the cross-border influences, both upstream and downstream, becomes crucial for preparedness and informing neighboring countries. If debris accumulation can be seen from orbit, it can be quantified—and if it can be quantified, it can be managed.
Furthermore, the collected results need to be the input for development of Transnational Joint Strategies and protocols that have immediate impact at reducing plastic pollution and safeguarding aquatic ecosystems through collaborative, cross-border action.
But these systems are needed for seas and oceans as well. One of projects is PREVENT project which has ambitious but obtainable goals which align with EU and global trends:
Joint Marine Litter Prevention and Management Strategy (JMLPMS)
Climate Resilient Adriatic-Ionian Action Plan (CRAIAP)
To further stress the importance of this subject, the EU Mission: Restore Ocean and Waters and Global Plastic Action Partnerships are making a huge effort in the area as well.
The sustainable development goals (SDGs) are the world’s most widely recognized framework for turning big sustainability ambitions into concrete, measurable action. Adopted as part of the UN’s 2030 Agenda, the SDGs connect environmental protection, resilient communities, and long-term economic stability — because progress in one area increasingly depends on progress in the others.
The UN Ocean Decade provides a convening framework for scientists and stakeholders from diverse sectors to develop the scientific knowledge and the partnerships needed to accelerate and harness advances in ocean science to achieve a better understanding of the ocean system, and deliver science-based solutions to achieve the 2030 Agenda. The UN General Assembly mandated UNESCO’s Intergovernmental Oceanographic Commission (IOC) to coordinate the preparations and implementation of the Decade.
At SeaCras, we, and as a result, our dear clients, align our work with SDG 6, SDG 11, SDG 13, and SDG 14 by using satellite-driven insights and data analysis to detect marine pollution, support early warning, and strengthen decision-making for cleaner water and healthier seas — especially across the Adriatic Sea and other vulnerable coastal regions.
How SeaCras maps to SDG 6, 11, 13, and 14
SDG 6 — Clean Water and Sanitation
We are aligned with the SDG 6 by using satellite AI to detect pollutants and monitor ecosystem health, and that also means our clients, thanks to using our technology and data, are aligned with the SDGs as well. SeaCras, regarding this Goal also provides authorities with scalable, high-resolution water quality data, enabling proactive protection of marine and freshwater resources globally.
SeaCras supports SDG 11 by enhancing coastal urban resilience. We provide satellite-based risk monitoring for “Target 11.5” to protect coastal settlements from pollution and climate-driven ecological disasters. A recent example is the devastating cyclone that caused severe damage in Sumatra, Indonesia. By partnering with us, stakeholders also strengthen their SDG 11 commitments by gaining credible, data-backed reporting and decision support that helps prioritise interventions, demonstrate impact to regulators and communities, and unlock sustainability-led opportunities.
SDG 11 focuses on making human settlements inclusive, safe, resilient, and sustainable. For coastal cities, marine pollution isn’t only an environmental issue — it affects public health, tourism, fisheries, and local infrastructure. SeaCras aligns with SDG 11 by translating complex marine conditions into actionable intelligence that helps municipalities such as Zavratnica and Jablanac area, ports such as Zadar Cruise Port, the Adriatic in its entirety, and regional actors make smarter, faster decisions — especially when risks escalate.
SDG 13 — Climate Action
SeaCras drives SDG 13 by monitoring ocean health indicators like algal blooms and water quality. Our satellite data provides vital climate intelligence to help coastal regions adapt to and mitigate the impacts of a warming planet. For our partners, this means earlier warnings, clearer climate-risk baselines, and stronger reporting — turning ocean insights into faster, better-funded resilience actions.
UN’s SDG 13 calls for urgent action on climate change and its impacts, including building resilience to climate-related hazards. SeaCras’ early-warning-oriented monitoring helps strengthen preparedness and response capacity where climate-driven extremes can worsen runoff and pollution events — supporting a more proactive, data-led approach to coastal risk management.
GOAL 14: Life Below Water
SDG 14 is specifically about conserving and sustainably using oceans, seas, and marine resources — with marine pollution named as a key threat. Our customers immediately get compliance here by detecting pollution signals, improving visibility over affected areas, and helping accelerate targeted action to protect marine ecosystems and the economies that depend on them. For partners, this delivers rapid, evidence-based insights they can act on, and report on with confidence.
SeaCras supports SDG 11, 13 and 14 by monitoring marine ecosystems, reducing pollution, aiding sustainable resource management, and providing data to research institutions for informed conservation and policy decisions.
Global Language for Sustainability
The sustainable development goals provide a shared global language for sustainability — making it easier to set priorities, measure progress, and collaborate across sectors. SeaCras’ focus on SDG 6, 11, 13, and 14 reflects a practical, outcomes-driven approach: protect water quality, strengthen coastal community resilience, improve climate readiness, and safeguard marine ecosystems through better visibility and faster, evidence-based response.
In short, when you can detect problems earlier and act with clarity, sustainability stops being aspirational — and becomes operational.
