A unique place in Croatia
A protected wetland where the Neretva River meets the Adriatic Sea and man reaps the fruits of the earth and the sea.
A thousand-year harmony attested by its natural history. The current speed of climate change causes a break in the balance of the coastal marine environment: today the sea enters the river delta, causing salinization. Biodiversity is at risk along with agriculture, the primary source of livelihood of the local communities. Monitoring these changes is critically important for the future of reed-nesting bird communities, numerous fish species, and crops.
The Neretva River delta
The Neretva River originates in the nearby Dinaric Alps of Bosnia and Herzegovina. From there, it flows for over 225 km until it reaches the Dalmatian coast of the Adriatic Sea, where its delta extends. The richness of this area is expressed through a varied landscape, from the numerous lakes surrounded by headlands to the lagoon. The meandering course of the river creates habitats of community interest for 150 marine and river fish species and for the wintering and migration of more than 300 species of seabirds. In fact, the area is protected by several international networks and conventions, such as the Ramsar Convention on Wetlands of International Importance. As a transitional coastal environment, the Neretva River mouth plays an important role in retaining sediment and protecting the hinterland from flooding, thanks to the presence of extensive reed beds, typical wetland vegetation.
Among vegetable gardens and orchards
On the strips of land that stand between the river and the sea, local communities, formed by around 35,000 people, practice traditional forms of agriculture using a canal system for drainage. The water flows along vegetable gardens, orchards and tangerine cultures, the main agricultural product from the area. Human intervention – especially the use of monoculture, causing pollution and habitat fragmentation – has left its mark on the ecosystems found in these wetlands. Here, in the brackish water of the lagoon, numerous species of marine fish, including eel, spawn. To protect the unique biodiversity of this environment, seven different protected areas were created in the estuarine area and surrounding lakes. Today, however, these areas face another threat: salt water intrusion.
A delicate balance between the river and the sea
The delta of the Neretva River meets the sea following a habitat gradient from the Baćina lakes, which originated from karst depressions, to the lagoon, where the water becomes brackish and reed beds are home to numerous species of seabirds and fish. The precious balance between fresh and salt water is threatened by climatic changes causing a decrease in rainfall, mainly in the summer seasons. As rainfall declines, the water level of the river lowers, giving way to the sea. Finally, the flow of salt water increases, encroaching into the mouth area.
Salt water intrusion impacts
Saline intrusion puts transitional habitats at risk. Freshwater species migrate and along with saltwater, marine and invasive species advance. Annual changes in ecological conditions often cause mortality and pose serious risks to native biodiversity. The changes occur in an area already scarred by further reduction of water flow, caused by the construction of hydropower plants in Bosnia and Herzegovina. Salinization changes the soil and endangers agricultural activities, fundamental for the livelihoods of local communities.
Monitoring the lagoon
To monitor the effects of salt water intrusion in the lagoon, thanks to the AdriaClim project, new sensors have been installed to detect salinity, oxygen levels, and water temperature at several locations in Neretva County between Baćina Lakes and the river delta. Thanks to the measurements, models on future seawater progression can be improved with new knowledge and data on the phenomenon. These models will enable better conservation of endemic biodiversity and provide valuable information to residents about possible risks to agriculture.
How is the marine climate changing
Not far from the Neretva delta, in the Slano Bay, a meteo-oceanographic station of the AdriaClim project has been installed that will collect more information on wind, precipitation, sea level and wave intensity to effectively plan for adaptation to future changes.
“We believe that our research will bring new knowledge about salt water intrusion in the Neretva River delta and that we will be able to provide reliable predictions of this adverse phenomenon in the future.”
Gordana Beg Paklar
Head of the Laboratory of Physical Oceanography at the
Institute of Oceanography and Fisheries (IOF), Split
A look into the future
The future of the Neretva Delta is closely linked to climate change on a local scale, and saline intrusion is likely to increase. Water scarcity, due to reduced rainfall and human intervention on the river course, threatens to undermine the delicate balance of fresh and salt water endangering the unique biodiversity of a transitional environment. Monitoring salt intrusion provides important data for climate change adaptation and risk reduction for biodiversity and agriculture in the upcoming years.