UA launches strategy to protect Uraba estuaries

UDEA/DICYT Fish in their early development stages (eggs and larvae) are extremely vulnerable to predation and become food for a wide variety of aquatic species. So they are usually found in areas that provide them food and protection from predators.

The Atrato River flows into the Caribbean Sea through more than 15 tributaries across the regions of Antioquia and Chocó, northwestern Colombia. “Mangroves are among the most common forms of estuarine habitats, however many different habitat types are found in and around estuaries, including arracachales and eneales, which are a type of grass commonly found in soft-sediment areas,” says UA biologist Tatiana Correa.

Mangroves serve as nurseries for young marine life. “Both saltwater and freshwater fish use estuaries to spawn. Also fish larvae migrate from the open sea to estuaries in order to complete development to the juvenile stage,” says biologist Juan D. Correa. “Coastal ecosystems such as coral reefs, seagrass beds, and mangroves play an important role in the development of these species,” Correa said.

These UA researchers are conducting a study to determine whether other ecosystems in the Atrato River delta also play an important role as a nursery area for new generations of fish.

To this end, researchers conducted a 12-month study consisting of monthly sampling in selected sites along the stretch of the estuary. “We used gill nets and trammel nets of different outer panel mesh sizes in order to collect samples at different development stages,” said Correa. “Mean values of temperature, salinity and transparency of the water were calculated. We also analyzed the levels of chlorophyll A, zooplankton and suspended solids,” she added.

The collected samples are analyzed in the laboratory to identify both which species they belong to and their stage of development.

“Research findings suggest that different fish species in their larval stage arrive at the Gulf of Uraba through ocean currents. However the study cannot provide reliable evidence on whether fish larvae arrive at this place to complete development to the juvenile stage,” Correa said.

What is clear is that the estuary provides food and shelter for species from distant ecosystems. “These findings highlight the importance of preserving marine ecosystems in order to maintain biological diversity in both freshwater and saltwater environments,” researchers said.

This study is not only aimed at highlighting the importance of understanding marine ecology but also seeks to raise awareness for the need to preserve marine ecosystems.

Environmental threats

“Overfishing and exploitation are major threats to estuarine habitats as well as artisanal fisheries. Some fish species are the most highly sought due to their large size and high-quality meat. However deforestation and contamination of mangroves remains the biggest threat to marine ecosystems,” biologist Juan Correa said.

Fish species such as grouper, snapper and snook may disappear from the Golf of Uraba if prompt conservation measures are not taken. This may have negative economic and social impacts not only on fishing-dependent communities but also on the nation’s food culture.

“Local ecological knowledge helps the fishermen identify most productive fishing spots, allowing them to know when marine fish such as snappers and tarpons enter coastal rivers after traveling hundreds of miles along the coast in search of food,” says professor Correa.

The local communities are aware that deterioration of coastal ecosystems can negatively affect not only fishery stocks but also their livelihood. Corpourabá, an autonomous organization aimed at fostering sustainable development in region of Urabá, has launched a project intended to develop strategies for mangrove conservation and to promote alternative uses of resources including beekeeping projects and using mangrove seeds for ornamental purposes.

Knowledge sharing between the local population and the scientific community is essential to carry out these projects and to find solutions for maintaining the health of coastal ecosystems.