Project Concept – Saving the pinstripe damba 

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“Community-based conservation is the only option open to practitioners who wish to conserve wetland biodiversity in Madagascar”. Evidence suggests that in Madagascar in the context of marine and freshwater conservation, where “community-based natural resource management projects have succeeded because the conservation agency involved and the community are interested in the same goal – usually increasing fish stocks.” Bamford et al., 2017

Madagascar – a biodiversity hotspot

Madagascar is renowned for its extraordinary flora and fauna. Even Hollywood has celebrated it. Madagascar’s west coast was formed approximately 165 million years ago when Africa broke away from Gondwanaland, and the island of Madagascar itself broke away from the Indian subcontinent approximately 75 million years later. The species found on Madagascar today are either descended from those species which were present on the island then or which have subsequently crossed the Mozambique Channel to reach the island. It is this prolonged geographical isolation coupled with the island’s climatic diversity which has promoted the evolution of such a famous and diverse wealth of endemic species – 90% of plants, mammals, reptiles and amphibians found on Madagascar occur nowhere else on Earth (Hannah et al., 2008). In fact, the unique biological diversity present on Madagascar has lent it to be referred to as Earth’s eighth continent. The island is home to more than 12,000 species of plant and 700 species of vertebrate animals. It is particularly notable not just for having endemic species, but for having entire branches (genera and families) on the tree of life which are only found here (Ganzhorn et al., 2008). An emblematic example of this are Madagascar’s most iconic residents, the lemurs.

Madagascar also remains a site of discovery. Between 1999 and 2010 615 new species were uncovered here, further evidence of the richness of the island’s terrestrial, freshwater and coastal environments (WWF 2011). The Island’s rich environment and natural resources are something that a high proportion of Madagascar’s 25 million people continue to rely on for subsistence and income generation. Of particular importance both to Madagascar’s people and its wildlife are the island’s wetland habitats. Madagascar has more than 300km of rivers and stream and approximately 2,000km2 of lakes divided across 256 catchments (Conservation International 2014). These fertile lands have been used for agricultural development and are important sites for many of the island’s terrestrial, freshwater and even coastal species.

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new species discovered between 1999 and 2010.
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of Madagascar’s animals and plants are endemic to the island.
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species of plant are native to Madagascar.

Freshwater life

Madagascar is recognised as a global hotspot for freshwater biodiversity (Benstead et al., 2003). Species inventories have to date described 183 freshwater fish species native to Madagascar, of which 106 are endemic to the island (Máiz-Tomé et al., 2018). The most species rich freshwater ecosystems in Madagascar are located in the northwest of the country. Large lakes within this region such as Kinkony, Andropogny and Ravelobe have historically supported highly endemic fish faunas. The small crater lakes on the island of Nosy Be also remain a key habitat for a number of endemic species and the caves and sinkholes in the south of the island are also home to a small radiation of endemic blind cavefish.

Madagascar’s riverine habitats are generally distinguished between its eastern and western flowing rivers. Western flowing rivers in the country dry out seasonally between November and April, and this has been hypothesised as a reason for the predominance of marine and brackish species which are found in these systems, and a lower level of freshwater fish abundance. The Eastern flowing rivers meanwhile hold a greater diversity of freshwater fish species, with 51 species including 22 endemics known from the rivers of streams of Madagascar’s eastern highlands (Máiz-Tomé et al., 2018).

There are a number of fish families which are particularly species rich on the island. The most species rich of all are the cichlids – with 29 species described from the island and one species (Pantanodon madagascariensis) already declared to be extinct on the IUCN Red List. Also of particular note amongst the Malagasy fish fauna are the family Betotiidae – commonly known as the Madagascar Rainbowfish. Just like the better-known lemurs, the entire family Betotiidae is endemic to Madagascar, comprising of 16 species. They are most closely related to the rainbowfish of Eastern Australia and New Guinea, from which they were separated at the time Gondwanaland broke apart.

As well as the number of endemic species present on the island, of particular interest to scientists studying Madagascar’s native fish fauna has been the number of species classified as “basal taxa” (Benstead et al., 2003). Basal taxa are species at the root of the evolutionary tree for a particular family and are vital to understanding the evolution of other species within that taxonomic group. For this reason, Benstead et al., (2003) recognise Madagascar as an important reservoir of genetic history for a number of freshwater fish families.  As well as these unique groups scientists have also been intrigued by the absence of certain species on the island. For example, there are no snakeheads, no knifefishes and no bagrid or airbreathing catfishes (Benstead et al, 2003).

Species status and conservation

Almost as well known as the endemic and diverse flora and fauna of the island of Madagascar is the level of threat that these species face. Madagascar has lost 80% of its original forest cover and many of its most charismatic species have experienced rapid population declines as the availability of primary forest habitat has decreased. For example, experts estimate that 95% of Madagascar’s 105 species of lemur are now threatened with extinction (Gaworecki 2018). The primary driver of habitat loss on Madagascar have been deforestation – according to analyses by the FAO in 2010 Madagascar was still losing approximately 57,000 hectares of forest cover per year (FAO 2011).

Deforestation not only affects forest species, but also has significant knock-on effects for Madagascar’s freshwater ecosystems. In fact, its freshwater environments are some of Madagascar’s most threatened and degraded environments (Bamford et al., 2017). This is exemplified by the fact that of the 12-bird species in Madagascar classified as Endangered or Critically Endangered on the IUCN Red List, 9 are wetland species (Bamford et al., 2017). Since 1960, Madagascar’s highland region wetlands have declined by 60% and in that same time period the country has also lost 37% of riparian forest (Kull 2012). Madagascar’s fish fauna are particularly vulnerable to extinction as a result of habitat loss because many species are not only endemic to the island but have small ranges within it, meaning the loss of a single site can drastically reduce a species chances of survival (see Stiassny and De Pinaa 1994).

A recent study by the IUCN’s Freshwater Biodiversity Unit into the conservation status of Madagascar’s freshwater fish fauna showed that 34% of species were threatened with extinction (Maiz-Tomé et al., 2018). However, even more alarmingly, assuming the same level of threat is also facing those species for which there was insufficient data (Data Deficient species),  this figure rises to 43% for all fishes, and to 78% for those endemic to Madagascar. Two species (Ptychochromis onilahy and Pantanodon madagascariensis) are also already classified as Extinct. The proportion of freshwater species assessed threatened with extinction was approximately twice as high as has been documented across the African continent as a whole (Maiz-Tomé et al., 2018).

The situation for these fishes is also currently getting worse – calculations show the expected rate of extinctions has increased in Madagascar from the first decade of this century to the second. Urgent conservation action is required to save these species and safeguard Madagascar’s wetland habitats.

Lake Tseny © Claire Raisin

References

Bamford A.J, Razafindrajao F, Young R.P, Hilton G.M, 2017, Profound and pervasive degradation of Madagascar’s freshwater wetlands and links with biodiversity, PLOS ONE 12(8): e0182673, https://doi.org/10.1371/journal.pone.0182673

Benstead P.J, Douglas M.M, Pringle M.C, 2003, Relationships of stream invertebrate communities to deforestation in Eastern Madagascar, Ecological Applications Vol.13, No.5, pp.1473-1490

Briggs J.C, 2003, Fishes and Birds: Gondwana Life Rafts Reconsidered, Systematic Biology, Vol.52, No.4, pp.548-553

Conservation International, 2014, Ecosystem profile: Madagascar and Indian Ocean Islands, Critical Ecosystem Partnership Fund, December 2014

Food and Agriculture Organization of the United Nations (FAO), 2011, State of the World’s Forests, FAO, Rome

Gaworecki M, 2018, 95 percent of all lemur species face high risk of extinction, experts say, Mongabay, Accessed 21.02.19, https://news.mongabay.com/2018/08/95-percent-of-all-lemur-species-face-high-risk-of-extinction/

Hannah L, Dave R, Lowry P.P, Andleman S, Andrianarisata N, Andriamaro L, Cameron A, Hijmans R, Kremen C, MacKinnon J, Randrianasolo H.H, Andriambololonera, Razafimpahanana A, Randriamahazo H, Randrianarisoa J, Razafinjatovo P, Raxworthy C, Schatz G.E, Tadross M, Wilmé L, 2008, Climate change adaptation for conservation in Madagascar, Biology Letters, Vol.4, Issue 4

Kull C.A, 2012, Air photo evidence of land cover change in the highlands: wetlands and grasslands give way to crops and woodlots, Madagascar Conservation and Development, Vol.7, pp.144-152

Máiz-Tomé L, Sayer C, Darwall W, 2018, The status and distribution of freshwater biodiversity in Madagascar and the Indian Ocean islands hotspot, Gland, Switzerland: IUCN

Sparks J.S and Smith W.L, 2005, Freshwater fishes dispersal ability, and non-evidence: “Gondwana Life Rafts” to the rescue, Systematic Biology, Vol.53, pp.11-19

Sparks K.S and Stiassny M.L.J, 2003, Introduction to the freshwater fishes, in: Goodman S.M and Benstead J.P (eds.), The Natural History of Madagascar, University of Chicago Press

Stiassny M.L.J and De Pinna M.C.C, 1994, Basal taxa and the role of cladistic patterns in the evaluation of conservation priorities: A view from freshwater, pp.235-249, in Forey P.L, Humphries C.J, Vane-Wright R.I (eds.) Systematics and Conservation Evaluation, Oxford: Clarendon Press