When Manuel Lopes-Lima got down to survey aquatic biodiversity on the Corubal River in 2022, he’d set his expectations very low. The river that straddles the West African nations of Guinea and Guinea-Bissau was, in spite of everything, very distant and grossly understudied.
Two expeditions later, the story has turned on its heels.
With the assistance of environmental DNA sampling and evaluation, Lopes-Lima and his crew recognized 125 species of aquatic and terrestrial vertebrates within the Corubal. This consists of critically endangered western chimpanzees (Pan troglodytes verus) and freshwater mussels (Pleiodon ovatus) in addition to 21 different species, largely fish, that weren’t recognized to exist in Guinea-Bissau.
“We weren’t anticipating the large variety that we discovered,” Manuel Lopes-Lima, group lead on the Analysis Centre in Biodiversity and Genetic Sources on the College of Porto in Portugal, informed Mongabay in a video interview. “We had been anticipating loads much less.”
In a examine= revealed within the journal Bioscience, the crew laid out the methodology they used to filter DNA from water samples collected from the Corubal. In line with the examine, the findings emphasize the “conservation significance of the Corubal, present a baseline for future monitoring, and spotlight the challenges and alternatives of eDNA surveys in distant tropical rivers.”
“Corubal is among the final free rivers in Africa,” Lopes-Lima mentioned. “There’s no main large metropolis alongside the river and no dams, and that makes this river notably attention-grabbing by way of conservation wants.”
Flowing almost 560 kilometers (350 miles), the Corubal rises from the highlands of Guinea, types a bit of the border with Guinea-Bissau, then meanders by the latter nation earlier than emptying out into the Atlantic Ocean. Alongside the best way, it serves as a supply of freshwater for animals residing within the river basin. Giant-scale research to watch biodiversity within the river haven’t been undertaken in recent times. Nevertheless, smaller expeditions prior to now have discovered the river and its basin to be residence to a large gamut of species, together with Senegal flapshell turtles (Cyclanorbis senegalensis), African manatees (Trichechus senegalensis), Nile crocodiles (Crocodylus niloticus) and hippos (Hippopotamus amphibius).
When Lopes-Lima and his crew determined to check the Corubal River, environmental DNA evaluation appeared like one of the best ways to grasp the biodiversity that lives there. Beforehand, Lopes-Lima used to dive or go snorkeling to check and monitor aquatic species. However this got here with challenges. “Particularly working in tropical rivers in distant areas, it’s typically harmful,” he mentioned. “There’s numerous parasites which is perhaps vectors of illnesses, and in addition harmful animals like crocodiles and hippos.”
Environmental DNA (eDNA) has discovered rising reputation as a noninvasive technique of conducting biodiversity surveys over giant areas. It requires amassing and detecting DNA left behind by animals in water, air and soil by way of their hair, fur and saliva, amongst different issues. Current research have additionally explored swabbing leaves in forests to assemble DNA samples of terrestrial animals.
Lopes-Lima and his crew undertook two expeditions, one in 2022 and one in 2023, to gather samples from the a part of the river that flows by Guinea-Bissau. Touring in slender canoes, the crew collected water samples from 25 factors alongside the river. From these, they extracted DNA to determine the species related to them.
The lately revealed examine covers solely the findings from the expedition in 2022. This consists of species that had beforehand not been recorded within the nation, such because the Egyptian fruit bat (Rousettus aegyptiacus) and the gray-throated rail (Canirallus oculeus). “It was attention-grabbing to see that we might perceive the biodiversity of the river itself, but in addition the animals that use the river to drink water or as a refuge within the dry season,” Lopes-Lima mentioned.
The crew additionally concurrently labored on constructing a reference database for species within the area. For this goal, they had been accompanied by a crew of scientists who collected specimens and tissues from animals to be able to construct a database, particularly for bugs, mollusks and smaller mammals that haven’t been well-represented in DNA reference databases. “The issue is that lots of the species in Guinea-Bissau had been by no means sequenced,” Lopes-Lima mentioned. “As a result of they’re so distant and troublesome to check, we didn’t have references for a lot of of them.”
Whereas the crew analyzes the samples from the 2023 expedition, it’s additionally planning a 3rd journey that may probably cowl the upstream a part of the river that lies in Guinea. The flexibility to assemble and course of a lot biodiversity knowledge from a distant tropical river has additionally inspired the researchers to forged a wider internet throughout the continent. Lopes-Lima mentioned he’s additionally presently working to coach scientists, develop eDNA protocol, and construct capability to conduct speedy biodiversity evaluation surveys in rivers in Namibia and different components of Southern Africa.
“We try to standardize and optimize these strategies to maximise the biodiversity you get whereas minimizing the fee,” he mentioned. “Not solely to see the biodiversity tendencies, however to make use of it for monitoring and see if conservation actions are serving to or not.”
Quotation:
Lopes-Lima, M., Prié, V., Camará, M., Ceríaco, L. M., Fernandes, V., Ferreira, S., … Beja, P. (2024). Fast eDNA survey reveals a singular biodiversity hotspot: The Corubal River, West Africa. BioScience, 74(6), 405-412. doi:10.1093/biosci/biae036
This article by Abhishyant Kidangoor was first revealed by Mongabay.com on 6 September 2024. Lead Picture: One of many species that had beforehand not been recorded within the nation is the Egyptian fruit bat (Rousettus aegyptiacus). Picture by Simon Willison by way of Flickr (CC BY-NC 2.0).
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