{"id":2177430,"date":"2024-09-09T06:00:46","date_gmt":"2024-09-09T05:00:46","guid":{"rendered":"https:\/\/focusingonwildlife.com\/news\/?p=2177430"},"modified":"2024-09-07T11:24:09","modified_gmt":"2024-09-07T10:24:09","slug":"scientists-find-unexpected-biodiversity-in-an-african-river-thanks-to-edna","status":"publish","type":"post","link":"https:\/\/focusingonwildlife.com\/news\/scientists-find-unexpected-biodiversity-in-an-african-river-thanks-to-edna\/","title":{"rendered":"Scientists find unexpected biodiversity in an African river, thanks to eDNA"},"content":{"rendered":"

When Manuel Lopes-Lima set out to survey aquatic biodiversity on the Corubal River in 2022, he\u2019d set his expectations very low. The river that straddles the West African nations of Guinea and Guinea-Bissau was, after all, very remote and grossly understudied.<\/p>\n

Two expeditions later, the story has turned on its heels.<\/p>\n

With the help of environmental DNA sampling and analysis, Lopes-Lima and his team identified 125 species of aquatic and terrestrial vertebrates in the Corubal. This includes critically endangered western chimpanzees (Pan troglodytes verus) and freshwater mussels (Pleiodon ovatus) as well as 21 other species, mostly fish, that weren\u2019t known to exist in Guinea-Bissau.<\/p>\n

\u201cWe were not expecting the huge diversity that we found,\u201d Manuel Lopes-Lima, group lead at the Research Centre in Biodiversity and Genetic Resources at the University of Porto in Portugal, told Mongabay in a video interview. \u201cWe were expecting a lot less.\u201d<\/p>\n

In a study= published in the journal Bioscience, the team laid out the methodology they used to filter DNA from water samples collected from the Corubal. According to the study, the findings emphasize the \u201cconservation importance of the Corubal, provide a baseline for future monitoring, and highlight the challenges and opportunities of eDNA surveys in remote tropical rivers.\u201d<\/p>\n

\u201cCorubal is one of the last free rivers in Africa,\u201d Lopes-Lima said. \u201cThere\u2019s no major big city along the river and no dams, and that makes this river particularly interesting in terms of conservation needs.\u201d<\/p>\n

Flowing nearly 560 kilometers (350 miles), the Corubal rises from the highlands of Guinea, forms a section of the border with Guinea-Bissau, then meanders through the latter country before emptying out into the Atlantic Ocean. Along the way, it serves as a source of freshwater for animals living in the river basin. Large-scale studies to monitor biodiversity in the river haven\u2019t been undertaken in recent years. However, smaller expeditions in the past have found the river and its basin to be home to a wide gamut of species, including Senegal flapshell turtles (Cyclanorbis senegalensis), African manatees (Trichechus senegalensis), Nile crocodiles (Crocodylus niloticus) and hippos (Hippopotamus amphibius).<\/p>\n

When Lopes-Lima and his team decided to study the Corubal River, environmental DNA analysis seemed like the best way to understand the biodiversity that lives there. Previously, Lopes-Lima used to dive or go snorkeling to study and monitor aquatic species. But this came with challenges. \u201cEspecially working in tropical rivers in remote areas, it\u2019s sometimes dangerous,\u201d he said. \u201cThere\u2019s a lot of parasites which might be vectors of diseases, and also dangerous animals like crocodiles and hippos.\u201d<\/p>\n

\"Scientists<\/a>
Scientists used eDNA analysis to identify 125 species of aquatic and terrestrial animals in the remote Corubal River in West Africa. Image by Manuel Lopes-Lima.<\/figcaption><\/figure>\n
\"The<\/a>
The Corubal River flows through Guinea and Guinea-Bissau. Image by Manuel Lopes-Lima.<\/figcaption><\/figure>\n

Environmental DNA (eDNA) has found increasing popularity as a noninvasive method of conducting biodiversity surveys over large areas. It requires collecting and detecting DNA left behind by animals in water, air and soil via their hair, fur and saliva, among other things. Recent studies have also explored swabbing leaves in forests to gather DNA samples of terrestrial animals.<\/p>\n

Lopes-Lima and his team undertook two expeditions, one in 2022 and one in 2023, to collect samples from the part of the river that flows through Guinea-Bissau. Traveling in narrow canoes, the team collected water samples from 25 points along the river. From these, they extracted DNA to identify the species associated with them.<\/p>\n

The recently published study covers only the findings from the expedition in 2022. This includes species that had previously not been recorded in the country, such as the Egyptian fruit bat (Rousettus aegyptiacus) and the gray-throated rail (Canirallus oculeus). \u201cIt was interesting to see that we could understand the biodiversity of the river itself, but also the animals that use the river to drink water or as a refuge in the dry season,\u201d Lopes-Lima said.<\/p>\n

The team also simultaneously worked on building a reference database for species in the region. For this purpose, they were accompanied by a team of scientists who collected specimens and tissues from animals in order to build a database, especially for insects, mollusks and smaller mammals that haven\u2019t been well-represented in DNA reference databases. \u201cThe problem is that many of the species in Guinea-Bissau were never sequenced,\u201d Lopes-Lima said. \u201cBecause they are so remote and difficult to study, we didn\u2019t have references for many of them.\u201d<\/p>\n

While the team analyzes the samples from the 2023 expedition, it\u2019s also planning a third trip that would potentially cover the upstream part of the river that lies in Guinea. The ability to gather and process so much biodiversity data from a remote tropical river has also encouraged the researchers to cast a wider net across the continent. Lopes-Lima said he\u2019s also currently working to train scientists, develop eDNA protocol, and build capacity to conduct rapid biodiversity assessment surveys in rivers in Namibia and other parts of Southern Africa.<\/p>\n

\u201cWe are trying to standardize and optimize these methods to maximize the biodiversity you get while minimizing the cost,\u201d he said. \u201cNot only to see the biodiversity trends, but to use it for monitoring and see if conservation actions are helping or not.\u201d<\/p>\n

Citation:<\/h2>\n

Lopes-Lima, M., Pri\u00e9, V., Camar\u00e1, M., Cer\u00edaco, L. M., Fernandes, V., Ferreira, S., \u2026 Beja, P. (2024). Rapid eDNA survey reveals a unique biodiversity hotspot: The Corubal River, West Africa. BioScience, 74(6), 405-412. doi:10.1093\/biosci\/biae036<\/p>\n

This article<\/a> by Abhishyant Kidangoor was first published by Mongabay.com on 6 September 2024. Lead Image: One of the species that had previously not been recorded in the country is the Egyptian fruit bat (Rousettus aegyptiacus). Image by Simon Willison via Flickr (CC BY-NC 2.0).<\/i><\/p>\n

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