Sorbonne Abu Dhabi study detects 83 vertebrate taxa along urban coastline

A new study led by Sorbonne University Abu Dhabi (SUAD) has detected 83 vertebrate taxa across four coastal sites in Abu Dhabi, offering fresh insights into marine biodiversity and the potential ecological importance of mangroves and seagrass habitats along one of the world's most urbanised coastlines.

Published in the scientific journal PLOS ONE, the study is the first environmental DNA (eDNA)-based survey of marine vertebrates in Abu Dhabi. Conducted in collaboration with the Environment Agency - Abu Dhabi (EAD) and France's National Museum of Natural History (MNHN), the research highlights distinct biodiversity patterns across coastal habitats with varying levels of development.

Researchers identified 83 vertebrate taxa, including 75 bony fish, two sharks and rays, one marine mammal and five birds. Of these, 22 were identified to species level.

The findings suggest that mangrove and seagrass habitats support greater phylogenetic diversity than some recently developed coastal sites. Phylogenetic diversity measures not only the variety of organisms in an ecosystem but also how evolutionarily distinct they are from one another.

The results offer an initial indication of the ecological value of these habitats, while researchers caution that further monitoring and comparisons with other ecosystems are needed to establish their long-term significance.

Mangroves and seagrass show distinct biodiversity patterns

The research examined four contrasting coastal environments in December 2024: Mangrove National Park, a seagrass bed near Al Futaisi Island, Marsa Al Bateen marina and Al Hudayriyat Channel.

Mangrove and seagrass habitats recorded higher levels of phylogenetic diversity, indicating the presence of more evolutionarily varied fish lineages than at recently developed sites.

Al Hudayriyat Channel, by comparison, showed lower phylogenetic diversity, suggesting that its marine community may still be developing. Marsa Al Bateen marina recorded intermediate levels.

However, the researchers stressed that the results should not be interpreted as definitive proof that Abu Dhabi's mangroves and seagrass beds are thriving biodiversity hotspots, as the study lacked a pristine reference ecosystem for comparison.

“These habitats still appear to support a structured and diverse fish community,” said Dr Jean-Luc Jung, professor at MNHN and visiting scholar at SUAD's Ocean Institute.

He cautioned against overlooking the findings, given the intense urban development surrounding the study sites.

“That is a signal we should not ignore: they likely play a critical role, and we risk losing it before we fully understand it,” Jung said.

DNA traces offer a new way to monitor marine life

The study uses environmental DNA, or eDNA, a technique that allows scientists to detect organisms through genetic material they naturally release into their surroundings. These traces can come from skin cells, mucus, scales and excrement.

Researchers collect and filter water samples under controlled conditions before using high-throughput DNA sequencing to identify the organisms represented in the samples. The method allows scientists to assess biodiversity without capturing, disturbing or directly observing animals.

Its non-invasive nature and ability to detect multiple groups of organisms through a single sampling protocol make eDNA a promising tool for monitoring complex marine ecosystems. Depending on the sample and analytical methods, it can help researchers identify fish, sharks, dolphins and birds, while careful sampling procedures remain essential to ensuring reliable results.

The approach could prove particularly useful in the Arabian Gulf, where marine life faces demanding environmental conditions, including summer water temperatures exceeding 35 degrees Celsius, high salinity and mounting pressure from human activity.

Understanding how species respond to these conditions is important for assessing the effects of environmental change and identifying habitats that may require closer protection.

Research brings together scientific expertise and local knowledge

The study forms part of the doctoral research of Rachel Haderle at MNHN, supervised by Jung, whose work has contributed to the development of methods for analysing eDNA-based biodiversity inventories and extracting broader ecological insights from them.

The research brought together SUAD's scientific leadership, MNHN's expertise in environmental DNA and molecular taxonomy, and EAD's knowledge of Abu Dhabi's marine ecosystems.

EAD identified the sampling locations, provided a boat and crew, and supported fieldwork and the required permits. Four agency scientists also contributed as co-authors.