Conservation recommendations - Conservation recommendations and research actions

Chapter 3 The status and distribution of freshwater fishes in western Africa

3.5 Conservation recommendations and research actions

3.5.1 Conservation recommendations

Freshwater ecosystems worldwide are subjected to a variety of anthropogenic threats. In western Africa it is now accepted

by scientists, development experts and even fishermen that environmental resources are being overexploited, depleted or require active restoration. In addition to the overexploitation of natural resources there are many other threats to western Africans fish such as manmade disturbances to system hydrology when constructing dams, a riverbed is mined, or a wetland is drained for agricultural purposes. Conservation and restoration of freshwater ecosystems therefore increasingly need to be recognised as global and regional priorities (Geist & Hawkins, 2016).

Conservation measures were identified and recommended by the experts involved for 36% of the species assessed.

The most frequently recommended measures include Site/

area management for 17% of species, Habitat & natural processes restoration (15% of species) and Awareness &

communications for 14 % of species (Figure 3.14).

It should be noted that consultations with stakeholders have been initiated but need to be strengthened throughout the region (CEPF, 2015). A number of investment initiatives have also emerged with a focus on the protection of ecosystems in the region (CEPF, 2015).

3.5.1.1 Site/area management and protection There are nearly 2,000 protected areas in western Africa with most of these being small forest reserves (UNEP-WCMC, IUCN and NGS, 2018), but very few have a focus on freshwater ecosystems, either in relation to their spatial cover or within their management plans. The findings from the assessments reported here highlight a number of areas notably rich in freshwater fish diversity where site protection would be beneficial. These sites include:

Figure 3.14 Conservation actions coded to fish species as part of the Red List assessment process. Source: Compiled by the report authors using data from the IUCN Red List (2021).

■ The forested coastal streams and rivers of Upper Guinea and Southern Guinea. This area is characterised by high species richness and endemism. More than 300 species are known from this area;

■ The Lower Niger Benue with its rich fish fauna, which includes around 289 species;

■ The Volta Basin, incorporating parts of Burkina Faso, Ghana and small part in Côte d’Ivoire and Benin, which includes around 240 species;

■ The interconnected network of rivers and coastal lagoons of the Bight Coastal ecoregion, and;

■ The Niger Delta with its rich fish fauna (an estimated 221 species) threatened by oil pollution.

Recommended management actions include:

■ The prevention of species extinction by addressing the immediate threats facing the priority sites and species;

■ Development and implementation of integrated catchment-based management plans

■ A greater focus on the need for transboundary management of those shared and hydrologically connected freshwater ecosystems, such as demonstrated by the Mano River Union comprising Liberia, Guinea, Sierra Leone and the Ivory Coast, jointly managing the transboundary Moa-Makona and Cavalla river basins,

■ Identification of additional priority sites as Key Biodiversity Areas for freshwater fish species (see Chapter 9 this volume).

■ Awareness campaigns to introduce governments and local populations to the international importance of these sites for fish biodiversity, and;

■ Establishment of fish conservation zones which have been demonstrated to be highly effective in other parts of the world (Koning et al., 2020).

3.5.1.2 Habitat restoration

As we enter the UN Decade for Ecosystem Restoration, we need to ensure a focus on the many degraded freshwater ecosystems in the western Africa region. As noted above freshwater ecosystems are being lost and degraded at an alarming rate as the collateral damage of our efforts to support a rapidly increasing human population. This, combined with the growing demands by countries outside of the region for natural resources, which are hugely contributing to the rapid expansion of agriculture and mining, is putting tremendous pressure on these ecosystems.

The assessments conducted here have identified where freshwater fish species are threatened due to habitat loss and degradation. We need to use this information now to inform priorities for habitat restoration to benefit freshwater fish species across the region.

3.5.1.3 Awareness and communications

The importance of maintaining aquatic biodiversity resources is not widely appreciated across all levels of society. The concept of biodiversity is still poorly understood and remains unknown to many people, and there is little understanding for the importance of biodiversity conservation amongst those people tasked with the development and management of dams, irrigated agriculture, the extractive industries etc. At the level of local communities and resource-users, the concept of natural resources is well understood but awareness of their own potential role in conserving or degrading these resources is often very limited. It is therefore important to launch public awareness campaigns at all levels on the current and future threats to freshwater biodiversity and the ways in which individual people can contribute to the future conservation of this resource.

3.5.1.4 Research actions

An analysis of the Red List assessments conducted here finds that for 76% of species specific research actions are recommended. Of these, the most commonly requested research themes are to monitor species “population trends”

(for 62% of species), and to understand more about species

“population size, distribution and trends” (56%), “life cycle and ecology” (49%), and “threats” (45%), Figure 3.15).

While some improvement is noted in our understanding of the diversity of freshwater fishes in western Africa, major gaps in our knowledge persist. This lack of a suitable information baseline represents a major impediment to the conservation of freshwater diversity (Smith et al., 2009). Where information is available on the inventory and distribution of species in a catchment, there is often little additional information such as on species ecology or threats to species and their habitats (Darwall et al., 2011). In the absence of such information, it is difficult to accurately assess the conservation status of the species and propose conservation actions. As noted at the time of the baseline Red List assessment completed in 2009 a major challenge was to reduce the total number of freshwater fish species classified as Data Deficient (55 species, or 10% of all species assessed). Since 2009 the number of species in this category has been reduced leaving just 32 species assessed (6%) as DD recognizing the important role of the ongoing fieldwork and other research in the region. However, these studies need to be continued and expanded alongside environmental and social impact studies which should be required as a prerequisite to any proposed development actions with the potential to impact on biodiversity. Much of the available data on freshwater fish species is also increasingly outdated and incomplete such that it remains difficult to assess changes over time, such as for the Red List Index (see Chapter 8).

The lack of recent or ongoing research to inform us on the status of the regions freshwater fish species suggests a paucity of focus on freshwater ecosystem research and conservation within the regions academic institutions. If this should prove to be the case then a strong recommendation would be to ensure greater inclusion of freshwater ecosystem research in academic curricular as an effort to generate a new generation of scientists to conduct this essential research.

These studies will ultimately improve our understanding of the ecology and life history of the fishes in western Africa as a key step towards their future restoration and conservation.

References

Abban, E.K. (1999). Considerations for the conservation of African Fish genetics for their sustainable exploitation.

In: Roger S. V. Pullin, Devin M. Bartley, & Jan Kooiman (eds.). Towards policies for conservation and sustainable use of aquatic genetic resources. [Online]. pp. 95–100.

Available from: https://portals.iucn.org/library/node/24418 [Accessed: 7 July 2021].

Abell, R., Thieme, M.L., Revenga, C., Bryer, M., et al.

(2008). Freshwater Ecoregions of the World: A New Map of Biogeographic Units for Freshwater Biodiversity Conservation. BioScience. [Online] 58 (5), 403–414.

Available from: https://www.doi.org/10.1641/B580507.

Anane-Taabeah, G., Frimpong, E.A. & Hallerman, E. (2019).

Aquaculture-Mediated Invasion of the Genetically Improved Farmed Tilapia (Gift) into the Lower Volta Basin of Ghana. Diversity. [Online] 11 (10), 188. Available from:

https://www.doi.org/10.3390/d11100188.

Bamba, M., Vreven, E.J. & Snoeks, J. (2011). Description of Barbus teugelsi sp. nov. (Cypriniformes: Cyprinidae)

from the Little Scarcies basin in Guinea, Africa. Zootaxa.

[Online] 2998 (1), 48–65. Available from: https://www.doi.

org/10.11646/zootaxa.2998.1.4.

Brainerd, T.R. (1997). Socioeconomic research needs for fisheries and aquaculture in Africa. In: J.H. Annala (ed.). Fisheries and Aquaculture Research Planning Needs for Africa and West Asia. [Online]. ICLARM. pp.

59–60. Available from: https://www.worldfishcenter.org/

publication/fisheries-and-aquaculture-research-planning-needs-africa-and-west-asia.

CEPF (2015). Ecosystem Profile: Guinean Forests of West Africa Biodiversity Hotspot. [Online]. Available from: https://

www.cepf.net/sites/default/files/en_guinean_forests_

ecosystem_profile.pdf [Accessed: 27 February 2020].

Daget, J., Gosse, J.P. & Thys Van Den Audenaerde, D.F.E.

(1984). Check-list of the freshwater fishes of Africa, Volume 1. Checklist of the Freshwater Fishes of Africa (CLOFFA).

Belgium, ISNB-MRAC-ORSTOM.

Daget, J., Gosse, J.P. & Thys Van Den Audenaerde, D.F.E.

(1986a). Check-list of the freshwater fishes of Africa, Volume 2. Checklist of the Freshwater Fishes of Africa (CLOFFA). Belgium, ISNB-MRAC-ORSTOM.

Daget, J., Gosse, J.P. & Thys Van Den Audenaerde, D.F.E.

(1986b). Check-list of the freshwater fishes of Africa, Volume 3. Checklist of the Freshwater Fishes of Africa (CLOFFA). Belgium, ISNB-MRAC-ORSTOM.

Daget, J., Gosse, J.P. & Thys Van Den Audenaerde, D.F.E.

(1991). Check-list of the freshwater fishes of Africa, Volume 4. Checklist of the Freshwater Fishes of Africa (CLOFFA).

Belgium, ISNB-MRAC-ORSTOM.

Dankwa, H.R., Biney, C.A. & DeGraft-Johnson, K.A.A. (2005).

Impact of mining operations on the ecology of river Offin in Ghana. West African Journal of Applied Ecology. 7 (1), 19–30.

Figure 3.15 Recommended research actions coded to fish species as part of the Red List assessment process. Source: Compiled by the report authors using data from the IUCN Red List (2021).

Dankwa, H.R. & Gordon, C. (2002). The fish and fisheries of the Lower Volta mangrove swamps in Ghana. African Journal of Science and Technology. 3 (1), 25–32. Available from:

http://hdl.handle.net/1834/636.

Dankwa, H.R., Owiredu, S.A., Amevenku, F. & Amedorme, E.

(2017). Environmental flow requirements and impacts of the Akosombo and Kpong dams on the fish and fisheries of the Lower Volta River, Ghana. In: Dams, development and downstream communities : implications for re-optimising the operations of the Akosombo and Kpong Dams in Ghana. Tema, Ghana, For the Water Resources Commission by Digibooks Ghana Ltd. pp. 43–61.

Darwall, W.R.T., Smith, K.G., Allen, D.J., Holland, R.A., et al.

(2011). The diversity of life in African freshwaters: under water, under threat: an analysis of the status and distribution of freshwater species throughout mainland Africa. [Online].

Cambridge, UK and Gland, Switzerland, IUCN. Available from: https://portals.iucn.org/library/node/9409.

FAO (1991). Report of the nineteenth session of the Committee on Fisheries. Rome, 8–12 April 1991. [Online]. p.59.

Available from: http://www.fao.org/3/am685e/am685e00.

htm [Accessed: 10 July 2021].

Geist, J. & Hawkins, S.J. (2016). Habitat recovery and restoration in aquatic ecosystems: current progress and future challenges - Geist - 2016 - Aquatic Conservation:

Marine and Freshwater Ecosystems - Wiley Online Library. Aquatic Conservation: Marine and Freshwater Ecosystems. [Online] (5), 942–962. Available from: https://

doi.org/10.1002/aqc.2702.

Helfman, G. (2007). Fish Conservation: A Guide to Understanding and Restoring Global Aquatic Biodiversity and Fishery Resources. Washington, D.C., Island Press.

Hugueny, B. & Lévêque, C. (1994). Freshwater fish zoogeography in west Africa: faunal similarities between river basins.

Environmental Biology of Fishes. [Online] 39 (4), 365–380.

Available from: https://www.doi.org/10.1007/BF00004806.

Koning, A.A., Perales, K.M., Fluet-Chouinard, E. & McIntyre, P.B. (2020). A network of grassroots reserves protects tropical river fish diversity. Nature. [Online] 588 (7839), 631–635. Available from: https://www.doi.org/10.1038/

s41586-020-2944-y.

Lalèyè, P. & Entsua-Mensah, M. (2009). Freshwater fishes of western Africa. In: Kevin G. Smith, M.D. Diop, M. Niane,

& W.R.T. Darwall (eds.). The Status and Distribution of Freshwater Biodiversity in Western Africa. [Online].

Cambridge, UK and Gland, Switzerland. pp. 20–32.

Available from: https://portals.iucn.org/library/node/9638.

Lederoun, D. & Vreven, E. (2016). Enteromius vandewallei, a new species of minnow from the Volta River basin, West Africa (Cypriniformes: Cyprinidae). Ichthyological Exploration Of Freshwaters. 27 (2), 97–106. Available from: https://limo.libis.be/primo-explore/fulldisplay?

docid=LIRIAS768127&context=L&vid=Lirias&search_

scope=Lirias&tab=default_tab&lang=en_US.

Lévêque, C. (1997). Biodiversity dynamics and conservation.

The freshwater fish of tropical Africa. Cambridge, Cambridge University Press.

Lévêque, C. (ed ), Paugy, D. (ed ) & Teugels, G.G. (ed ) (1990).

publisher: MRAC. Faune des poissons d’eaux douces et saumâtres de l’Afrique de l’Ouest: Tome 1. Collection Faune tropicale 28. [Online]. Paris, France, MRAC and ORSTOM. Available from: https://agris.fao.org/agris-search/search.do?recordID=AV2012061551 [Accessed:

4 May 2021].

Lévêque, C., Paugy, D. & Teugels, G.G. (eds.) (1992). publisher:

MRAC. Faune des poissons d’eaux douces et saumâtres de l’Afrique de l’Ouest: Tome 2. Collection Faune tropicale 28. [Online]. Paris, France, MRAC and ORSTOM.

Available from: https://agris.fao.org/agris-search/search.

do?recordID=AV2012061551 [Accessed: 4 May 2021].

Lévêque, C., Paugy, D., Teugels, G.G. & Romand, R. (1989) Taxonomic inventory and distribution of freshwater fish from the coastal basins of Guinea and Guinea Bissau- fdi:

30065- Horizon. Revue d’Hydrobiologie Tropicale. 22 (2), 107–127.

Paugy, D., Lévêque, C. & Teugels, G.G. (2003). The Fresh and Brackish Water Fishes of West Africa. 40. [Online].

Muséum national d’Histoire naturelle. Available from:

https://sciencepress.mnhn.fr/en/collections/faune-et- flore-tropicales/poissons-d-eaux-douces-et-saumatres-de-l-afrique-de-l-ouest-vol-1-2 [Accessed: 4 May 2021].

Petr, T. (1968). Distribution, abundance and food of commercial fish in the Black Volta and the Volta man-made lake in Ghana during its first period of filling (1964–1966).

I. Mormyridae. Hydrobiologia. [Online] 32 (3), 417–448.

Available from: https://www.doi.org/10.1007/BF00155400.

Pezold, F., Schmidt, R.C. & Stiassny, M.L.J. (2016). A Survey of Fishes of the Geebo – Dugbe River Confluence, Sinoe County, Liberia, with an Emphasis on Tributary Creeks aqua, International Journal of Ichthyology. aqua, International Journal of Ichthyology. 22 (3), 97–122.

Available from: https://aqua-aquapress.com/a-survey- of-fishes-of-the-geebo-dugbe-river-confluence-sinoe-county-liberia-with-an-emphasis-on-tributary-creeks/.

Schmidt, R.C., Bart, H.L. & Pezold, F. (2016). High levels of endemism in suckermouth catfishes (Mochokidae:

Chiloglanis) from the Upper Guinean forests of West Africa.

Molecular Phylogenetics and Evolution. [Online] 100, 199–205. Available from: https://www.doi.org/10.1016/j.

ympev.2016.04.018.

Schmidt, R.C., Bart, H.L., Pezold, F. & Friel, J.P. (2017). A Biodiversity Hotspot Heats Up: Nine New Species of Suckermouth Catfishes (Mochokidae: Chiloglanis) from Upper Guinean Forest Streams in West Africa. Copeia.

[Online] 105 (2), 301–338. Available from: https://www.doi.

org/10.1643/CI-16-474.

Schmidt, R.C., Dillon, M.N., Kuhn, N.M., Bart, H.L., et al. (2019).

Unrecognized and imperilled diversity in an endemic

barb (Smiliogastrini, Enteromius) from the Fouta Djallon highlands. Zoologica Scripta. [Online] 48 (5), 605–613.

Available from: https://www.doi.org/10.1111/zsc.12362.

Schmidt, R.C. & Pezold, F. (2011). Morphometric and molecular variation in mountain catfishes (Amphiliidae: Amphilius) in Guinea, West Africa. Journal of Natural History. [Online]

45 (9–10), 521–552. Available from: https://www.doi.org/

10.1080/00222933.2010.534560.

Smith, K.G., Diop, M.D., Niane, M. & Darwall, W.R.T. (2009).

The Status and Distribution of Freshwater Biodiversity in Western Africa. [Online]. IUCN, Gland, Switzerland and Cambridge, UK, International Union for Conservation of Nature (IUCN). Available from: https://portals.iucn.org/

library/node/9638.

Thieme, M.L., Abell, R., Burgess, N., Lehner, B., et al. (2005).

Freshwater Ecoregions of Africa and Madagascar: A Conservation Assessment. Island Press.

Trape, S. (2016). A new cichlid fish in the Sahara: The Ounianga Serir lakes (Chad), a biodiversity hotspot in the desert. Comptes Rendus Biologies. [Online] 339 (11), 529–536. Available from: https://www.doi.org/10.1016/j.

crvi.2016.08.003.

UNEP-WCMC, IUCN and NGS (2018). Protected Planet Report 2018. [Online]. p.56. Available from: https://portals.iucn.

org/library/node/48344 [Accessed: 16 May 2020].

United Nations (2019). World Population Prospects 2019, Online Edition. [Online]. Available from: https://

worldpopulationreview.com/continents/western-africa-population [Accessed: 10 July 2021].

Valdesalici, S. (2013). Pronothobranchius chirioi n. sp. a new annual killifish species from the Niger River drainage, with redescriptions of P. kiyawensis, P. gambiensis and P. seymouri (Cyprinodontiformes: Nothobranchiidae).

Killi-Data Series. 21–41.

Welcomme, R.L. (1991). The Conservation and Environmental Management of Fisheries in Inland and Coastal Waters. Netherlands Journal of Zoology. [Online]

42 (2–3), 176–189. Available from: https://www.doi.

org/10.1163/156854291X00261.

World Bank (2005). Ghana: Natural Resources Management and Growth sustainability. p.227.

Zhang, A.T., Urpelainen, J. & Schlenker, W. (2018) Power of the river: Introducing the global dam tracker (GDAT). 33.

Available from: https://www.energypolicy.columbia.edu/

research/report/power-river-introducing-global-dam-tracker-gdat.

Chapter 4 The status and distribution of freshwater molluscs in western Africa

Van Damme, D.¹, Darwall, W.R.T.²

Contents

4.1 Overview of western African molluscs ...37 4.1.1 The Sahelian freshwater malacofauna ...37 4.1.2 The Guinean forest freshwater malacofauna ... 38 4.1.3 The Atlantic brackish water malacofauna. ... 38 4.2 The history of scientific research on western African freshwater molluscs ... 38 4.3 Conservation status ... 39 4.3.1 Gastropoda ... 39 4.3.2 Bivalvia ...42 4.4 Species richness patterns ...42 4.5 Major threats to freshwater molluscs... 45 4.5.1 Pollution ... 45 4.5.2 Natural system modifications ... 45 4.5.3 Climate change and severe weather ... 46 4.5.4 Agriculture and aquaculture, residential and commercial development ... 46 4.5.5 Biological resource use ...47 4.5.6 Energy production and mining ...47 4.6 Conservation recommendations ...47 4.6.1 Site/area protection ...47 4.6.2 Resource and habitat protection ... 48 4.7 Species in the spotlight – unravelling the mysterious decline of Pleiodon ovatus ... 49 References ... 50

1 Laboratory of Palaeontology, Ghent University, Krijgslaan 281, S8, B-9000 Ghent, Belgium

2 Freshwater Biodiversity Unit, Global Species Programme, IUCN (International Union for Conservation of Nature), David Attenborough Building, Pembroke Street, Cambridge, CB2 3QZ, UK

4.1 Overview of western African molluscs

In western Africa, freshwater mollusc communities can be subdivided into two distinct freshwater communities that populate the vast region of the arid to hyper-arid savannah in the north and the east, and the western belt of Nigerian and Guinean lowlands. A third species-rich brackish water community comprises the estuaries, lagoons and mangrove forests along the Atlantic coast.

4.1.1 The Sahelian freshwater malacofauna

The Sahelian community includes large parts of Senegal, Mali, Chad, Burkina Faso, Niger and Nigeria and extends to the Atlantic via the Dahomey Gap (Togo and Benin).

Even though the largest natural surface waters of western Africa, namely Lake Chad and the Middle Niger Delta, are found in this savannah, the freshwater malacofauna is poorly diversified and dominated by genera that can survive limited periods of aridity or increasing salinity, such as Pila, Lanistes, Gabbiella, Melanoides, Bulinus, Biomphalaria, Lymnaea and Spathopsis. This limited diversity stems in large part from climate oscillations which cause the shallow surface waters, such as Lake Chad, to fluctuate from total desiccation about 20,000 years ago during the period of the Glacial Maximum to an enormous surface area (350,000 km²) known as Lake Mega-Chad between 7,000 and 5,000 years ago (Holocene Pluvial). Since then the lake has been shrinking and reached a new minimum size in the years 1970–1980 (Bouchette et al., 2010).

Therefore, it is not surprising that the present malacofauna consists of species that originally colonised the region of Mega-Chad during the last wet period, then retreating southwards into the Chari and Logone river basins and eastwards into the Nile Basin. Most of these species are hence widely spread either throughout the entire Sahelian belt or over the western part of it, with a few endemics confined to the Middle Niger and the Chari-Logone basins.

Some species such as Gabbiella neothaumiformis and Gabbiella tchadiensis were originally considered endemic to the Lake Chad basin but their status as distinct species needs further investigation, as they are probably local morphotypes belonging to widespread species. As the present study is not focused on solving ongoing taxonomic questions, the treatment of these species is as valid full species is therefore maintained until additional material becomes available.

Finally, a recently published checklist of the fresh and brackish water snails of Benin confirms that the freshwater malacofauna occurring in the Dahomey Gap region has low species diversity consisting of largely ubiquitous species (Koudenoukpo et al., 2020). The brackish water snail fauna is comparatively richer.

4.1.2 The Guinean forest freshwater malacofauna

In complete contrast to the Sahelian malacofauna, the Guinean forest supports high species richness and a high degree of endemicity to the tropical wetlands and rainforests that formerly extended from Guinea to the Sanaga River in Cameroon.

This ecotope is ancient and, based on its malacofauna, formerly occurred also in eastern Africa. It now forms the last refuge for a malacofauna that predates the disappearance of tropical wetlands over much of Africa during the last five million years. Four gastropod genera, Afropomus, Saulea, Sierraia and Soapitiai, are endemic to the rivers of this region, while many Potadoma species have strongly restricted distributions, being confined to limpid ion-poor forest rivers. The bivalve fauna consists mainly of a high number of Iridinidae. It is remarkable that until the mid-20th Century the malacofauna of these western African wetlands remained free of genera that were dominant and widespread over the rest of the continent such as Bellamya (one dubious species

在文檔中 Identification and validation of Western African freshwater Key Biodiversity Areas (頁 43-0)