Chapter 4. Freshwater molluscs of Africa: diversity, distribution, and conservation

Seddon, M.¹, Appleton, C.², Van Damme, D.³ and Graf, D.4

1 Bracken Tor, Saxongate, Okehampton, Devon, EX20 1QW 2 School of Biological and Conservation Sciences, Westville Campus, University of KwaZulu-Natal, Durban 4000, South Africa 3 University of Ghent, Sint-Pietersnieuwstraat 25, B 9000 Ghent, Belgium 4 Department of Biological Sciences, University of Alabama, Tuscaloosa AL 35487 USA

The Kulungu River, part of the Chambeshi basin in the Upper Congo. © DANIEL GRAF AND KEVIN CUMMINGS

Diving for mussels in the Upper Chambeshi River, Upper Congo. © DANIEL GRAF AND KEVIN CUMMINGS

IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 92 4/3/11 18:37:12 CONTENTS 4.3.1 Regional patterns of threat 112 Introduction 94 4.3.2 Dams 113 4.1 Overview of freshwater molluscan diversity in Africa 96 4.3.3 Water pollution 114 4.1.1 Molluscan diversity in river basins 97 4.3.4 Sedimentation 114 4.1.2 Molluscan diversity in ancient lakes 100 4.3.5 Invasive species – water hyacinth and other plants 114 4.1.3 Molluscan diversity in artesian basins 102 4.3.6 Invasive species – fi sh farming 114 4.1.4 Molluscan diversity in saline lagoons, saltmarshes and mangroves 102 4.3.7 Invasive species – molluscs and their impact on indigenous species 114 4.1.5 Molluscan diversity in crater lakes 103 4.3.8 Climate change 117 4.1.6 Molluscan diversity in montane lakes 104 4.4 Understanding the impact of molluscs on 4.2 Conservation status and distribution of human health and livelihoods 117 freshwater molluscs 104 4.5 Recommended conservation measures 118 4.2.1 Threatened species 105 4.5.1 Recommended research actions 119 4.2.1.1 Changes since the 1996 assessment 106 Species in the spotlight – Freshwater molluscs are 4.2.2 Restricted range species 106 important – especially to the African openbill stork 120 4.2.3 Data Defi cient species 109 Species in the spotlight – Can the last populations of the 4.2.4 Extinction patterns 110 giant African freshwater pearl mussel be saved? 123 4.2.5 Undescribed species 111 Species in the spotlight – A mollusc with a bit 4.3 Main threats 112 of muscle 124

Children washing clothes in a steam near the Sanaga River in Cameroon, potentially exposed to diseases hosted by freshwater molluscs. © KEVIN SMITH

IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 93 4/3/11 18:37:15 IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 94 94 CHAPTER 4 | MOLLUSCS north-eastern north-eastern Africa, central Africa and western Africa comparison have In 1935). (Germain Mozambique for studies Germain’s as well as 1939) Connolly (e.g., monographs Connolly’swith various centuries, two last the throughout attention received have Africa, Some southern as such regions, Africa. western including regions from molluscs fi the rst of some described and Africa, in malacologists earliest the of one was Adanson 1994). (Brown continent the throughout expansion colonial of periods the during commenced molluscs freshwater African of Exploration accompanying DVD. the see please region, than rather grouping taxonomic by resultsof synthesis presenteda For actions. conservation further require that species and regions the highlighting and fauna continental the providing to threats the fauna, of overview molluscan an pan-African entire the for 2010; Graf Kristensen 2005; al. et were determined Africa through a series of assessments central (Darwall and northern in western, molluscs southern, of eastern, status regional the 2009, to 2003 From over thenextfi ve years. described species endemic of number increased an have (West (Van Damme species known of number the changing rapidly collections, is historical of review with combined survey, fiof level the eld Africa, northern already.In genera some of studies in happened has multiply,as well may known species of number the – systematics those molecular utilising especially – continue reviews taxonomic as that and faunas, American EuropeanNorth as and attention of tropical level same the received the yet not have molluscs freshwater that recognise to need We prosobranchs. however, have, the and mussels Unionid years freshwater the on concentrated recent in efforts research Most higher a proportion of the containing widespread, more cosmopolitan species. pulmonates the with Gastropoda, the than numerous less are Bivalvia The pulmonates. the and prosobranchs the groups, informal two into dividing latter the main with Gastropoda, two the and Bivalvia into the groups, fall molluscs Freshwater 2008). Bogan comm.; pers. (Seddon species) European 780 about are there which (of Palaearctic the for species 1,540 around and America North for species 880 around to compared species 560 estimated an only with Europe, and North America in as less such faunas are continental some Africa than of diverse molluscs diversity. freshwater the freshwater general, changing In our understanding for ecological proxies as use their complex underscore which of all interactions, exhibit and strategies are life-history gastropods) varied have and habitats, freshwater of range wide a in found (bivalves molluscs Freshwater Introduction 03, n tee ra cn e xetd to expected be can areas these and 2003), al. et et al. 2010), as is also the case in Lake Tanganyika et al. 2011). This chapter synthesises the results 2009a,b; Van Damme Van 2009a,b; al. et et al. et

for their overall pan-African status. Most of these would these of Most status. pan-African overall their for evaluated be not could hence and assessments, regional earlier the in omitted were that valid, considered project pan-African the which species some are there such, As of that with genus the of concept taxonomic the changed, has name the while Regardless, comm.). pers. (Graf, forms living to material that relating shells, and neontologists took a conservative approach to Chambardia, of species type the the that for been have basis to seems The confusion 1998). Daget 1989; (Vaught priority name the that recognized been since has it taxon, this circumscribedunder species as genus the to referred others and (1988) Mandahl-Barth 1990s, late the Through reports. regional various the in ways different in assigned genus the mussels, example, freshwater For in list. taxonomic the for basis initial the as taken was which on differeddepending have project this in treatments regional the such, As comm.). pers. (Graf shells species of form the of variability the of opinions on mainly defi data, on nitive based is neither but lumping, and splitting of schools taxonomic two the of nature the reflbivalves, of ecting status the of views different rather two provide volumes These (1988). Mandahl-Barth and with (1998) Daget of catalogues the in Bivalvia, presented activity most the of studies few are there contrast, By focus ofvariousstudiesoverthelast30years. the been have taxa these such, as and pulmonates, are species host the of Many handbooks. small and papers research many produced and Africa, in of scientists young generation a supporting programmes training many Mandahl-Barth date. established the Danish Bilharzia Laboratory, to which hosted gastropods freshwater the of remains the most complete handbook to the identifi Mandahl- cation 1994) days, (Brown monograph early Brown’s Brown. the D. and in Barth work the of majority the contributed scientists notable of Two importance. molluscs medical to related studies taxonomic for attention of focus the been also years, 50 last the for has, Africa efforts are looking at the origins of other pulmonate genera. researchfurther and Planorbidae), Family the in subfamily a (now Ancylinae the of origins the Albrecht on more revealing C. is by research Recent families. prosobranch incorporating molecular systematics continues on selected (West produced been a TanganyikaLake has recently,of Gastropods to handbook revised More faunas. lake African East on volumes published both Mandahl-Barth G. and (1935) Leloup E. 1950s, the In work. survey recent more of result the as Smith and K. von Martens have been considerably revised E.A. as such researchers by Tanganyika Lake of studies early Valley.The Rift ancient the of fauna unusual the to due partly attention, more received fauna African eastern The years. 50 last the in attention little relatively received s cnuin hud e limited. be should confusion so Spathopsis, C. , letourneuxi was described from (sub)fossil t al. et s interchangeable is Chambardia . However, given the given However, Spathopsis. has nomenclatural has Chambardia 03, n frhr research further and 2003), a been has Chambardia 4/3/11 18:37:17 CHAPTER 4 | MOLLUSCS 95 4/3/11 18:37:21 et al. 2001; Cummings Unionid mussels collected from Malebo Pool in the Republic of the Congo; Chelidonopsis hirundo (LC), Mutela legumen , Coelatura (LC), M. “rostrata” (VU), Aspatharia pfeifferiana ed snail. (VU), C. gabonensis (LC) and an unidentifi rotula © OLIVERLUCANUS/BELOWWATER.COM and Ancylinae. There evaluated been are not have also that Physidae a family the number in species of introduced native range. Africa is outside their given that bivalves Freshwater The freshwater bivalves represent approximately 25% of the freshwater mollusc fauna of the African continent. In total, we recognise 158 species (28 genera, nine families, two of orders) bivalves in Africa, including 17 species that differences to due project this of part as evaluated not were in taxonomic treatments in the regional assessments that assessments. nal pan-African the basis for the fi provide orders: distributed globally two into divided are bivalves The Unionoida (otherwise known as freshwater mussels) and Veneroida (otherwise known as clams and pea-clams). species of number higher the contain mussels Freshwater (82 species). All unionoid species are strictly freshwater, locally often and common are molluscs these Africa in and abundant inhabitants of both rivers and lakes. Similarly, the Veneroida (56 species, including brackish ve from habitats, of range wide a occupy evaluated) fi species not estuarine waters to interior lentic and lotic environments, although there are more cosmopolitan taxa in possess bivalves the freshwater the of All pea- (Sphaeriidae). clams These freshwater. in life to adaptations of suite common a include larval brooding, direct development, and, in the case of freshwater mussels, obligate shes upon (Wächtler larval freshwater fi parasitism derived characters common these Despite 2009). Graf and © HEINZ H. BÜSCHER be assessed as This Data variability cient in knowledge Defi from or family to between Least family and regions Concern. presented a to this considerable assessment and, although challenge ongoing research has considerably increased our knowledge of the fauna, there remains a pressing need for continued investment and knowledge base. training to build on the current gastropods Freshwater Freshwater gastropods represent freshwater about molluscs 75% in the of African into all continent, two dividing informal groups, higher the revised (2005) Rocroi and Bouchet pulmonates. the prosobranchs and the could “Prosobranchia” that noting Mollusca, of phylogeny no longer be supported as a formal was polyphyletic, designation, with as multiple origins it within the group. Now there are two major clades, the Caenogastropoda and the Heterobranchia, along with smaller clades such as Neritimorpha. Within the informal group “Pulmonata”, similar problems have also been found, however most of the freshwater species lie in the Basommatophora, within the Eupulmonata. Brown (1994) were 326 estimated species in Africa, but that more species have been there been have species new as study current this in recognised described and molecular systematics allowed some taxa to be revised. lakes the within varied most are prosobranchs Freshwater and larger river systems, whereas freshwater pulmonates are more often associated with small water-bodies and species 353 total, In drying. seasonal of tolerant are many of prosobranch and 143 Planorbidae, in the here, families Lymnaeidae, recognised species of pulmonates are (LC), a species endemic to Lake Tanganyika, (LC), a species endemic to Lake Tanganyika, Tiphobia horei where it is locally impacted by sedimentation, dredging and collection for the shell trade. IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 95 IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 96 96 CHAPTER 4 | MOLLUSCS n Grioy i Gomrde n Jnis 1998) of hotspots Jenkins projected the of map and generalised a provide Groombridge (in Gargimony and Bouchet Africa. of regions different the in found be can and habitats basins these of all river and 2000), (Seddon large basins artesian lakes, ancient in diversity and Freshwater molluscs fi nd their highest levels of endemism 4.1 Overview offreshwater molluscan compiled byBouchetandGargimony, adaptedfrom Groombridge andJenkins1998). Figure 4.1.Hotspotsoffreshwater molluscdiversity across continentalAfrica(highlightedinorange)(data f hi dsaae ie itre, eosrt a ag of ofdispersalandabundance. patterns range a demonstrate histories, life disparate their of result a as and, lineages evolutionary different represent taxa bivalve these pressures, environmental shared from diversity inAfrica shared with the Palaearctic fauna, the Arabian fauna and fauna Arabian the fauna, Palaearctic the with shared elements has which Africa north-eastern is exception The south of the Sahara where an Afrotropical fauna dominates. regions the and fauna, Palaearctic the with lies fauna the affithe where Sahara, of the nity of north regions the into African freshwater mollusc fauna is geographically divided species distributions,ratherthanexperts’bestestimates. mapped actual of basis refithe be on to ned picture this defias of Africa of enable diversity and species 1998, in hotspots ned the of 4.2) (Figure comparison in-depth an allow now project pan-African current the of outputs The Africa western of rapids river the and Lakes ValleyRift African East the namely Africa, of parts various highlighting world, the in diversity freshwater molluscan (Figure 4.1). (Figure 4/3/11 18:37:26 CHAPTER 4 | MOLLUSCS 97 4/3/11 18:37:31 Burnupia Burnupia and Ferrissia 2005). Brown (1994) Brown 2005). al. et 4.1.1 Molluscan diversity in river basins The two largest freshwater systems in Africa Congo are the the Nile largest, the of habitats The rivers. Congo the and are River, the less diverse, consisting mainly of rainforest (Thieme lakes rift large and rivers and Van Damme and Van Bocxlaer (2009) compared the species richness of uvial the mollusc fl faunas of these two river basins, with exclusion of the large lakes. Brown the from known gastropods of number the that out pointed take we (if (96) Congo the of that half about is (51) Basin Nile cient genera the taxonomically defi as genera only), and the proportion of basin endemics is the for Similarly, species. 51 of out 10 namely lower, much a with Basin, Nile the in lower is diversity species bivalves, Lower Congo Lower et al. 2010). The southern the African fauna (Van Damme Rapids. Additional regions of highlighted in Bouchet interest and Gargimony’s analysis (Figure not previously 4.1) include the North African African coastal spring-snails, rivers, Lower the Nile River, East the Lake Chad basin and Malebo Pool in the Congo Basin. line for the Palaearctic fauna is generally drawn through the Ahagger Mountains, north-east towards Libya 1961). west to Mauritania (Sparks and Grove and highest the having as study this in highlighted regions The species diversity (Figure 4.2) include Lakes (Lake the Victoria, Lake and Tanganyika Lake Malawi), East African the Upper Congo catchments around Lake Mweru, the and Africa, western the of regions rapid river Figure 4.2. Patterns river/ per of species = number richness Species species. all mollusc for species richness of Figure lake sub-catchment. IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 97 IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 98 98 CHAPTER 4 | MOLLUSCS The KulunguRiver, partoftheChambeshibasin intheUpperCongo. oe ae n rne etitd pce. o example For species. restricted range and rare some Basin Congo ago). years million 5.3 to (23 times Miocene Late and Middle in Africa of Horn the via Africa into molluscs freshwater of invasion main Damme limited number of endemics with a Palaearctic origin. Van widespread a with along range, including their of limits southern the at occur,species fauna Palaearctic the of components Libya), and Tunisia Algeria, (Morocco, zone and Maghreb the with as Highlands, Ethiopian the in and Nile Sphaeriidae (Families (Egyptian) mussels In Lower the are more abundant. Corbiculidae) smaller pea and and snails pulmonate clams Basin Nile dominant, the in overwhelmingly while are bivalves unionoid and snails prosobranch Basin Congo the In pools. temporary Nile the such Basin is as taxa in living of habitats, fringe in generalist diversity highest the lakes, and rivers the in live that taxa is specialist for Basin of Congo the richness species highest the While found. is diversity this where in the habitats dissimilarity also (2009) observed Bocxlaer 1998; Graf Vanand 2007a,b). Cummings Damme and Van (Daget Basin Congo the in 18 to compared as Basin Nile the to endemic fi species only ve with Basin Nile the in lower is dramatically and endemism the of degree bivalve total of 28 species compared to 38 in the Congo drainage, . (2010) suggest this pattern stems fromthestems pattern this suggest (2010) al. et : The fauna from the Congo Basin includes Basin Congo the from fauna The : Pseudogibbula, rangesfrom SomaliaMozambique to (fourspecies), whilst and African is (Eussoia) another birds), by spread is it as by Brown (1994) is family the In fiAfricathe in recognizedof genera one Assimineidae, Endangered.ve Critically as listed species in rocks on fi xed limpet shallow fast fl a owing water. like This species is the only lives it where habitats, inhabitssimilarCongo),the (RepublicofRiver Kouilou the oftributary a recentlydiscoveredinwas which neritoides, western in taxa Africa. In the similarfamily Ampullaridae, another thespecies, are as relicts, probably are genera These area. Congo Lower the in found exclusively flfast in stones areon andstreams, life owing to adapted and Liminitesta Gongodoma, thereare three monotypic genera in the family Bithyniidae, speciose, but only one species, one only but speciose, Afro-Asiangenus the Thiaridae family the In 2003). Pickford and Damme (Van Africa eastern to extended formerly range genus’ the that and distribution relict a is this that shows evidence Fossil basins. these VoltarepresentativesRiver,the withinitsrareand areand genus the Paludominidae, family the ranges In identifi threats. restricted and ed their to due Endangered Critically as listed are genera three these of representativesRiver.All flfastCongo theLower restrictedtothe areof part owing © DANIELGRAFANDKEVINCUMMINGS is restricted to the Lower Congo Congo Lower the to restricted is Pseudocleopatra Valvatorbisand Assiminea (which is fairly cosmopolitan, (fourSeptariellina species) hc ae all are which Funduella, Melanoides tuberculatus , Melanoides isMelanoides highly Lanistes Lanistes

4/3/11 18:37:34 CHAPTER 4 | MOLLUSCS 99 4/3/11 18:37:36

Coelatura (Mandahl- © JEAN-PIERRE BOUDOT Nitia is limited to Nilo- The Oued Za in Morocco, a typical river of the Maghreb. Unio, Anodonta, Leguminaia Anodonta, Unio, Nitia are listed from Africa (plus Anodonta is a widespread Eurasian and North Potomida that inhabit the Palaearctic region of The highest species richness is found in Cameroon, with seven species, most of which are threatened. Within the freshwater mussels the genus Sudanic Africa, including the been Senegal, frequently have Niger, genus Chad, this of and species The Basins. Nile subsumed under the catchall genus, Barth 1988; Scholz and Glaubrecht 2004), but we regard worthy species, of group distinct morphologically a as Nitia of separate (Daget recognition 1998; Graf and Cummings 2007a). Three species of one that was not evaluated), all of which are assessed as cient. either Least Concern or Data Defi The Niger River basin contains fewer endemic of species freshwater molluscs than the Congo systems. and Similarly, Nile other river rivers such Orange, and Zambezi, as whilst having the reasonable species Senegal, diversity, have relatively few endemic species. Some of c these western African rivers require do, specifi however, unique and rare few the safeguard to actions conservation species occurring in owing, the highly fast-fl oxygenated waters of the river rapids. North-west Africa: The mussels freshwater of this region of genera the within largely are and northern Africa, the Maghreb, and parts of Europe. The genus American genus that, in the western Palaearctic, reaches

Sierraia Potodoma et al. 2008). Potadoma (which was moved from ca 30 parthenogenetic species are restricted to the (family Bithyniidae), that are adapted to life on on life to adapted are that Bithyniidae), (family Soapitia species in the family Pachychilidae has a disjunct dispersion dispersion disjunct a has Pachychilidae family the in species (in the Atlantic rivers from Liberia to Lower also Congo in and eastern and north-eastern Congo). This taxon had formerly ancient a as much reaching wider distribution, far east as the Turkana Basin (Van Bocxlaer is is found throughout Africa (and Asia), while most of the other species highest the with Congo, the and lakes African large richness found in the Congo Basin, where 12 species are recorded. Species of Thiaridae Thiaridae to Pachychilidae on the research (Köhler basis and Glaubrecht 2002)) of are found molecular in the rapids of the Lower Congo and also in eastern and north- threatened. eastern and some of these are Congo, Western Africa: The is western region recognised African (Mittermeir biodiversity terrestrial of hotspots the of one as Prosobranch unique some of presence the and 1998), al. et genera in owing the rivers short, draining fast-fl the west Africa plateau is ection of a the refl area’s high diversity. The rivers draining the west Africa plateau have localized range restricted species, including two genera, and Guinea, and Leone Sierra in streams owing fast-fl in stones and to these as genera be are considered well threatened as being potentially quite ancient and relict in origin. The River Niger is less diverse than many of the fast- smaller, (Thieme that drain the owing rivers plateaus west African fl the Congo, the in and region this In 2005). al. et IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 99 IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 100 100 CHAPTER 4 | MOLLUSCS species, from the continent, three of which are threatened. Four new and eastern, northern, four total, In Africa. southern in distribution wider a with but Endangered. Critically as ranked are species both inhabit, they rivers the to threats the and ranges, distribution restricted their represent endemic species suggests that these north-western African populations may Damme (Van work recent More 2007). (Graf concepts species and methods only just begun to be re-evaluated using modern analytical century,last have the they in and fromearly areholdovers the traditional concepts of Palaearctic genera and species (Araujo Asia Central and Russia into Palaearctic, extending east from the British Isles and Iberia western the in widespread and variable morphologically species, European declining but conspecifiwidespread two with c areAlgeria Morocco and populationsin the that been has of two species which to as malacologists among disagreement is there although species, two by representedare Maghreb its southern limit in north-western Africa. Populations in the Table 4.1.Freshwater gastropod faunaofthelargestAfricanlakes(BasedonBrown 1994andadditionaldata): and Africa central and eastern between lie that valleys rift the in located mainly are lakes ancient the Africa, In 4.1.2 Molluscandiversityinancientlakes as well as the Turkana Basin. Unio assemblage, extending from the Maghreb to the Nile, Palaearctic- the of widespread most the is species latter species, endemic African regard the African populations of we Moreover, Endangered). (Critically foucauldianus U. of African populations north-western the treat we Here species. other with synonymy from removed recently only being project, U. ravoisieri nor (Araujo peninsula Iberian adjacent the in found arealso four all Africa; north-western Maghrebof mancus, have recently been recognized as occurring in the Lake Turkana Lake Kivu Lake Tana Lake Edward Lake Mweru Lake Albert Lake Chad Lake Malawi Lake Victoria Lake Tanganyika Lake and cygnea A. no gibbus, Unio hy r. h mr taiinl view traditional more The are. they Anodonta is another typically Palaearctic genus, genus, Palaearctic typically another is Unio as a separate endemic species, species, endemic separate a as gibbus U. U. delphinus were evaluated as part of this 00 Aaj pr. comm.) pers. Araujo 2010; al. et . delphinus, U. . Those taxa are both both are taxa Those anatinus. A. A. pallaryi and Ednee) The (Endangered). durieui U. species are recognized are species Unio liue()Ae k² o fseisNo.oflakeendemics No.of species Area (km²) Altitude (m) U. mancus to be another 2009). However,2009). al. et 1,829 1,240 1463 and ravoisieri, U. 375 920 922 615 280 473 773 2009).Neitheral. et A. lucasi. Due to U. U. 20,000 29,600 75,000 32,900 2,700 7,200 3,156 2,150 4,850 5,600 from thegenusLavigeria. A LakeTanganyika gastropod(demonstratingshellrepair) 94, n sm edmc pce hv spectacular have species ornamentation, with shell-forms endemic called thalassoid, meaning some and 1994), Brown 1953; (Leloup zones sub-littoral and littoral the in al. 2003). The endemic prosobranchs are principally found (Westlake the to endemic being fauna Metazoan the of of the East Africa Rift Valley lakes, with approximately half Lake Tanganyika is viewed as one of the oldest and deepest the pulmonates(Brown 1994). of endemism and diversity limited more a is there whilst largest lakes, Tanganyika, Victoria and Malawi (Table. 4.1), In general, the prosobranchs are most diverse in the three distinctive speciestoevolve. of presence the for suffi periods for cient isolated been have may lakes small these even that out points (1994) Brown although lakes, ancient the in recognized change evolutionary and isolation of levels same the have not do and this is confi rmed here (Figure 4.2). Other smaller lakes (Westmolluscs of diversity and endemism high their for recognized long-been have 10 15 15 16 21 27 28 83 7 4 © HEINZH.BÜSCHER 2003; Michel 2003; al. et 1 subspecies 1 subspecies 0 species 4 subspecies 8 species/subspecies 8 species/subspecies 3 species/subspecies 17 species 12 species/subspecies 65 species 2004), al. et et 4/3/11 18:37:40 CHAPTER 4 | MOLLUSCS 101 4/3/11 18:37:41 Lanistes Lanistes Bellamya Bellamya Coelatura Coelatura Bellamya. 4 species/subspecies 8 species 1 subspecies 3 species 6 species/subspecies 1 species/subspecies Melanoides (Brown 1994). Nyassunio nyassaensis were 2011), and the taxonomic the and 2011), al. et Eupera crassa, which is assessed as 8 12 11 10 17 12 , are categorized are nyassaensis, Chambardia L. nasutus is a thin shelled elegantly shaped in Lake Victoria has yet to be to yet has Victoria Lake in bourguignati Mutela 2007). Some of the more widespread families widespread more the of Some 2007). al. et between the two lakes (Brown 1994). The shore is mixed, with rocky shores separated by sandy bays estuaries, and and small the lake-level is known to be seasonal changes subject in rainfall since to the Quaternary Period. Currently, no endemic genera are Malawi, recognized unlike in in Lake Lake Tanganyika. Again, number there of are a lake endemic molluscivorous sh dependent fi on that the are presence of molluscs source. A as number of their genera are highly food specious in Lake Malawi. For example, the family Thiaridae includes eight endemic species in the genus Recent molecular studies have shown that these endemic eight species, with highly distinctive shells, differ genetically do and are parthenogenetic clonal not lineages (Genner also include localized endemic species, such as nasutus, an apple-snail (Ampullaridae) that is restricted to Lake Malawi. 46 to 82m. Of the deep-water species found at a depth of species, two Malawi, Lake to endemic mussels freshwater and alata Mutela sedimentation, of impacts to due Vulnerable, as hypsiprymna was assessed as Near Threatened, whilst the other endemics such as Least Concern.considered Lake Victoria is shallower than (maximum depth of the 80m), has a other lower salinity than Lake great lakes Tanganyika, and possesses a shoreline with papyrus swamps, open extensive sandy beaches and stony shores some within variability considerable is There 1994). (Brown in be either may these suggests (1994) Brown and species, levels, lake low of periods from speciation partial of status a or are just ned poorly requiring defi further investigation of their genetic distinctness. The African viviparid fauna in the lake included six species in the genus of status determined. rigorously Ongoing investigations by Lange (pers. comm.) should provide better knowledge of the true distribution ranges of populations within the lake as, for example, phthinotropis has a restricted range within the lake, being currently only found in the south-west part. Freshwater mussels of note are Critically Endangered, and Aspatharia divaricata, which is (Graf Vulnerable considered 4,850 7,200 32,900 29,600 75,000 20,000

Moncetia, Nyassunio Nyassunio et al. 2003). Spathopsis), Brazzaea anceyi is 773 375 473 280 922 M. anceyi, which is 1,240 Altitude (m) (km²) Area species No. of endemics No. of lake (and Chambardia Pseudospatha tanganyicensis Lavigeria sp X, etc. (West et al. (2004) to suggest that the lake molluscs 2003). Various fi sh, also endemic to et the al. lake, 2003). fi Various Lavigeria sp P, Lake Tanganyika Lake Turkana Lake Malawi Lake Chad Lake Mweru Lake Lake Victoria These species vary in their threatened status, depending on their range and the localized impacts of sedimentation t along the lake These shore. species would groups benefi more as revised, been has taxonomy the once review from species may be found to be threatened if their ranges are more restricted than currently thought. prosobranch The species, numerous with extremely variable led Michel shapes, shes fi cichlid the as way same the in ocks fl species formed (West dependent are on the of presence these molluscs as their food source. Freshwater bivalves: Richness of bivalves is lower than that of gastropods in the largest African Lakes (see Table 4.2) There are three genera of African freshwater mussels Tanganyika. Lake to endemic and monotypic each are that Grandidieria burtoni and ujijiensis, are known from few specimens, and as a result their status is cient. Data Another Defi genus, are are assessed as Least Concern, but as such mussels, Other Vulnerable. considered is represented by a single species apparently also endemic to and Lake is Tanganyika listed as Near Threatened. Mandahl-Barth of synonym (1988) a be to considered Moncetia and reported that this species had never been collected by study the of unaware apparently was he however alive; Kondo (1984). Lake Malawi is less Tanganyika, saline with a and mollusc fauna shallower which than is endemic about to Lake the 60% lake and with no gastropod taxa shared ‘sea-like’, as there is a marked convergence with marine found are molluscs few that suggests (1994) Brown shells. below 125m depth, due to the concentration of hydrogen sulphide. Freshwater prosobranchs: In the family Paludomidae, 20 genera belong to the subfamily Hauttecoeuriinae, and 19 of these are restricted to Lake Tanganyika. The most genus dwelling rock non-thalassoid the is genus speciose However, species. 18 include to thought is which Lavigeria, although a diagnostic key does exist, a number of these indicated being described, fully been yet not have species by Table 4.2. Freshwater bivalve fauna of the largest African lakes. African of the largest fauna bivalve Freshwater 4.2. Table IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 101 IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 102 102 CHAPTER 4 | MOLLUSCS View fromnearKigali,Rwanda. Lakesregion oftheGreat extirpated (Van Damme locally are or threatened as assessed are prosobranchs Damme Van1998; (Ghamizi regions mountainous limestone the in aquifers by fed springs in found is region Maghreb the in (Strong 49% – species (252 Australia and 18%) – species America 105 (around North comm.)), pers. (Seddon 69% – species 610 (around Europe with contrast in 11%), – species (69 region, Maghreb spring-snails form a lower proportion the of the endemic fauna especially Africa, In Hydrobiidae. family the from spring-snails the comprises largely and basins, artesian in found world, for the of as parts other is, many molluscs freshwater of diversity highest The 4.1.3 Molluscandiversityinartesianbasins which isassessedasEndangered. regarded as Vulnerable, and are note of Species well as two endemic monotypic freshwater mussel genera. shallow lake. There are eight endemic Gastropoda taxa, as this of richness unusual the on commented (1994) Brown and fauna, the of vulnerability the on commented (1927) Bequaert and Pilsbry fringes. the along swamps papyrus and marshes extensive with 1994)), (Brown depth (15m shallow very is which lake, of edge south the into drains also present in the lower reaches of the Luapula River which these species are restricted to the lake, whereas others are Zambia, has several endemic species of mollusc. Some of Lake Mweru, a lake in the upper part of the Congo Basin in 00. oe hn 5 o te Maghrebian the of 75% than More 2010). al. et 2008)). The majority of this diversity this of majority The 2008)). al. et wih is which mweruensis, Mweruella et al. 2010). By contrast, there are Prisodontopsis , aviculaeformis © IUCN/INTUBOEDHIHARTONO coastline. The saline lagoons have some very restrictedthe of range partslarge fringe thatmangroves and saltmarshes lagoons, saline the in found are species range-restricted more the of Africa some However, Afrotropical variation. spatial little of show habitats coastal the of Molluscs 4.1.4 Molluscan diversityinsalinelagoons, be threatened. to considered not are such, as and, drying-out of tolerant species widespread more typically are habitats these in The freshwater bivalves and most of the pulmonates found diversity unknown further within thesesystems. be may there such, as and, groundwaters interstitial diffisampling the of to culty due largely surveyed, be to remain that waters artesian with region the of parts large however, are, There genera. 20 than more to number the raise could Algeria, in particular in investigation, further that likely is it but region, the from known are genera 13 least At hydrobids. subterranean of radiation and evolution of centre a is Maghreb the Africa, (Arconada and Ramos peninsula 2003; Iberian Benke the and Balkans the (e.g., limit glacial greatest the of south the regions limestone the in found are radiations Europe, neighbouring In genus. endemic One of these, the origin reflof of these radiations a and ection the lack possibly of limestone regions. Sahara, the of south fauna proportionately few endemic hydrobiids in the Afrotropical saltmarshes andmangroves Lobogenes, is a central and southern African et al. 2009)). In northern 4/3/11 18:37:44 CHAPTER 4 | MOLLUSCS 103 4/3/11 18:37:48 Gabbiella Gabbiella tropicus toroensis; these taxa which is distributed widely in the Bulinus Lake Awing, one of the crater lakes in Cameroon. © KLAAS-DOUWE DIJKSTRA Mytilopsis Mytilopsis africanus, western Africa, extending from Senegal to The the sole Congo. Afrotropical representative of the Dreissenidae is estuarine/brackish waters of coastal western Africa, from species these of Most Congo. the of mouth the to Senegal the where some, although Concern, Least as assessed are Data as categorized are uncertain, were data distributional cient. Defi in crater lakes 4.1.5 Molluscan diversity Crater lakes in present are many parts of Africa, including Cameroon, Ethiopia and eastern sheltered, Africa. but These deep lakes small, are usually cient species-poor, they below are 20m often as depth oxygen and, defi in some cases, are too saline for molluscs. probably Some lakes, these colonise species to managed however, have, though transportation by birds, and their relative isolation may have driven their evolution into new Cameroon species. crater The lakes have a richer fauna be than expected, might including one possibly endemic Bulinus species, camerunensis (EN). In the western Uganda crater lakes eight gastropods and three bivalves were recorded by Mandahl-Barth, including two endemics, kichwambae and systematics, molecular using investigations, further require 1994). to establish their status (Brown

Saulea, which are et al. 2009a), so the found in southern southern in found Tomichia Tomichia are sensitive to changes in Afropomus and Cyrenoida, of the family Cyrenoididae, Littoraria. Most of the African littorinids are not species, such as the species of species the as such species, Africa. All species of the with interference and pollution by caused habitats their seasonal wet-dry regime (Kristensen as threatened. been assessed majority have By contrast, the mangrove species throughout habitats suitable in found are and widespread, tend to be more the continent. For example, a the cosmopolitan family family Littorinidae represented is in Africa species of by a few considered to be threatened. However, in some regions, such as the coastal swamps of western nd Africa, you fi the “living fossils”, A team of Moroccan and Spanish malacologists aided by local in the Oued Abid marocana youngsters collecting Margaritifera (Morocco). After tissue samples were taken, the animals of this last viable population of the species were placed back in the river. © MOHAMMED GHAMIZI are are found in brackish/estuarine habitats in tropical monotypic, are considered to be rare, and are threatened. threatened. and are to be rare, considered monotypic, are Three families of bivalve are typically found in of comprised mainly are families brackish these and habitats, water marine species. Recent checklists have listed 19 species western (Daget Africa tropical from Donacide family the of 1998; Bogan 2010). However, only been 14 evaluated for of the these IUCN Red have List. Egeria occur Ten in species coastal western Africa of (plus four species of unknown distribution that were species not that evaluated; was evaluated one is now considered Two invalid). species of IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 103 IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 104 104 CHAPTER 4 | MOLLUSCS Table 4.3.ThenumberofAfricanmollusc speciesineachIUCN Red ListCategory, byregion. in 1994. This survey used the fi rst set of quantitative IUCN Brown David by undertaken gastropodsfreshwater the of Red List of Threatenedof List Red Species The fi rst species from the region to be placed on the IUCN 4.2 Conservation statusoffreshwater continental Africa,inthegastropod groups: a)the prosobranchs; b)thepulmonates;andc)bivalves. Figure 4.3.Theproportion (%)offreshwater molluscspeciesineachregional IUCNRedListCategoryinmainland and increased frequency ofdrought. variability climate to due levels lake in changes potential species for sport fi shing, as well as by their vulnerability to lakes are threatened bytheintroduction ofnon-nativefi sh montane these in Species montigenum). (P. Threatened Near and (P.Vulnerableartifex ) as assessed are 2001) al. (Warui Africa Eastern in lakes montane high-elevation in occurring species more Two Ethiopia. to in lakes limited few a distribution a having Endangered, Critically as species), such species, (six Defisome cient Data or species) (six Concern clams pea- Afro-tropical the of species most Although isolation. their of result a as also possibly species, endemic support some and isolated, are these lakes, crater the for As (amountainlakeorpool)athighaltitude. have smalltarns Ethiopia and Africa eastern in areas mountain high The 4.1.6 Molluscandiversityinmontanelakes precautionary measure notincluded inthepan-Africalistingsforendemic species. *Some subspeciesregarded asspeciesinregional treatments, and undescribed taxaincludedinregional treatments, are asa Pan-Africa Africa Northern Central Africa Western Africa Africa Southern Africa Eastern Region molluscs (Pisidium p. ae sesd s en o Least of being as assessed are spp.) r considered are ethiopicum, P. oo pce hetnd%DataDefi cient %Threatened No ofSpecies

came fromcame reviewmajor a 624* 228* 155 159 122 95 et 29% 45% 31% 12% 22% 9% e in seis Ti, n at rflet te ee o recent of refl level part, the in ects Defi This, species. cient proportion of threatened species and the proportion of Data the in regions the between variability considerable is There ongoing globalassessmentofallfreshwater molluscs. an to contribute will assessments regional These ranges. their of part African the within status their determine to completed been also have assessments regional Africa, List. For those species with distributions extending beyond arespecies endemic all Red for IUCN global the to added assessments that such status, global their to equivalent is status List Red IUCN regional their Africa, continental to endemic species those For 2001). (IUCN regionalscale a the on 3.1 Version applying Criteria: and Categories by List Red IUCN assessed was species mollusc each freshwater of of status conservation In the fauna. project, molluscan this freshwater region’s the of status that conservation study the fi of rst overview the comprehensive a provides is project pan-African IUCN This biodiversity forthecontinent. freshwater of status the of overview an provide not could fi obtained the gures so and species, Concern Least or DefiData the of any for assessments include not did cient review, Brown’s published by IUCN (Baillie However,and Groombridge 1996) Africa. western and lakes Valley Rift African the in hotspots regional the in found those mainly criteria (version 2.3) and resulted in the listing of 68 species, 28% 17% 19% 24% 16% 38% 4/3/11 18:38:02 CHAPTER 4 | MOLLUSCS 105 4/3/11 18:38:07

et al. the majority of in the Lower Congo Rapids and Malebo Sites Sites highlighted as having the most threatened species Victoria, (Lake Lakes African East the Maghreb, the include and Lake Tanganyika Lake Malawi) and the a Congo Basin include to shown is catchment Chad Lake The 4.4). (Figure taxonomic require these but species, threatened of number requiring as highlighted been not have such, as and, review conservation actions. In the Congo Basin, endemic species a Pool quarter were representing as assessed threatened, of the total molluscan richness in those areas (Graf 2011). Most of these were range-restricted species living within specialised habitats, such as rapids. Pilsbry and vulnerability Bequaert of the fauna (1927) of ongoing an the however, is, There lling. Lake infi gradual Mweru its to Africa commented in central on the These factors should be taxonomic research, the eld amount survey, theof recent fi application of molecular systematic, and the number of local scientists and overseas researchers working most on the each are prosobranchs the general, In group. taxonomic the by followed group, molluscs freshwater the of threatened 4.3). 4.3; Figure bivalves and then the pulmonates (Table species distribution patterns4.2.1 Threatened Apparent regional variations in the distribution patterns ect of regional differences threatened species in part refl in the status of taxonomic research, work, levels and numbers of range restricted of endemic species, survey which are often threatened. taken into consideration when interpreting the speciesdistribution maps. Figure 4.4. The distribution of threatened freshwater mollusc species across mainland continental Africa. Africa. continental mainland across species mollusc freshwater of threatened distribution 4.4. The Figure sub-catchment. of species per river/lake = number Species richness IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 105 IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 106 106 CHAPTER 4 | MOLLUSCS Cape Province, South Africa. neartheEastern only knownfromonelocation, a stream Tomichia speciescurrently cawstoni,aCriticallyEndangered rcuinr apoc, uh ht h tre endemic genus threethe in species the the that followed such have approach, precautionary we Here, threatened. considered not were that River Luapula the of reaches lower the in presentalso species those and species endemic the both impact to infi likely of is rate ll the whether to as debate changed the total number of species and the number of number the and species of number total the changed the previous assessment in 1996, and some of these have There have been several major changes in taxonomy since 4.2.1.1 Changessincethe1996assessment species are relatively widespread. the of majority the as molluscs, for so less but 2009), al. (Darwall taxa freshwater threatened of groups other for important considered were headwaters Zambezi The are monitored closely. populations that important still is it occurrence, limited its consideration into Taking Threatened. Near therefore as assessed is it and inhabit, snails these that springs to the threats plausible known no are there as threatened, as assessed be cannot it range, restricted a has rogersi although that noted Africa South in species Tomichia all of populations of status present the of review recent vulnerable to destruction by man (Brown 1994). This more (Tomichia Endangered one and natalensis), (Tomichia Endangered one assessed as Extinct (Tomichia 1996), Groombridge and (Baillie List Red IUCN 1996 the in included were species three Africa, South in occurring Herbert (1998) noted that of the seven species of streams. freshwater perennial to pans saline temporary from ranging habitats in regions coastal the in found are endemics unusual more the of some Africa, southern In isassessedasEndangered.aviculaeformis which Vulnerable of regardedand as is mweruensis Mweru, Lake to endemic also are genera mussel freshwater monotypic Two Endangered. ), as the habitats of all were considered were all of habitats the as rogersi), Bellamya © DAIHERBERT are assessed as Critically as assessed are cawstoni), one Critically Prisodontopsis Mweruella Tomichia et T.

h nrhr Arcn ein a wl a suh n east and south as of well as most region, for African true northern is the This Africa. of rest exceptionally the only throughout found are species range Restricted Atlas, andMoyenAtlasmountain rangesintheMaghreb. Anti Saharien, Atlas Atlas, Haut isolated the and Congo; of the vast, diversifi ed and old hydrographic system of the and system, rift eastern the in largelakes the of presence the Cameroon; in and Africa western of part southern the in particularly drainages, coastal smaller the of some of is age relative great the reasons: This of number a to prosobranchs. due partly are which of most gastropods, Africa is a continent with many restricted range freshwater 4.2.2 Restrictedrangespecies criteria themselves. information, and changes to the thresholds of the Red List new changes, taxonomic rather but the species the of status in changes refl genuine (1996) ect Brown by made the of few conclusion, observed changes in category from the In 1996 assessments interpreted. be should data are conducted,including, forexample,thewaythatrange assessments way the in changes of number a to led have guidelines the and 3.1) (version Criteria and IUCN Categories the of version latest the above, mentioned effort In addition to the taxonomic changes and increased survey the previously knownfaunaand thenewlydescribedspecies. of distribution the of knowledge our increased has TanganyikaProject, Lake Biodiversity GEF the with along recent research and survey work by West from resulting gastropods Tanganyika Lake within the descriptions species new been also have There sources, and hence are now considered to be threatened. as range restricted, with threats from exploitation of water regarded are some species, 13 than more into spilt been has species the now however, Concern; Least therefore species, single a As mothers. the of copies exact are descendants their that and stable, very been have differentmorphs the that found and history geological the reviewed (2005) al. Heller make-up. genetic in little very vary but colour and form shell in spectacularly differ that lineages clonal creates reproduction asexual that arguing species, single Brown’swas a as Brownconsideredthem opinion. (1994) species, single a to belonging than rather are These Endangered. Critically currently considered as distinct species (Heller are which of some species, 13 about by represented is it where Maghreb, family family,this in genus One 1988). the from split characters (Houbrick anatomical of basis the wasThiaridaeon Melanopsidae family The to impacts species conservationstatus. consequent with species, restricted range . praemorsa M. a cniee wdsra and widespread considered was occurs in the in occurs Melanopsis, et al. (2003). This work, M. praemorsa, M. et al. 2005) et 4/3/11 18:38:09 CHAPTER 4 | MOLLUSCS 107 4/3/11 18:38:14 some of which of some Tomichia, (found on the coast of Natal) and Natal) of coast the on (found ned to small are stretches confi of the coast of Natal and the Cape Province. Species with the most restricted ranges, sometimes of only a few square metres, are the Maghrebian hydrobids that are found in one or two springs or they extensive, more be may wells. underground range true their Although are assessed as threatened on a precautionary basis, as the extent of their range in artesian waters is whereas wells, the uncertain; to restricted truly be may species some others which are only seen in ood are actually fl events distributed at more widely outlets in the groundwater supplying the outlets.

Septaria of the Atlas range, i.e., Mauritania, Mali, and Libya, southern Algeria central and Egypt, the whole of the north- eastern African Region (Eritrea, Sudan, Ethiopia, Djibouti and Somalia), with the exception of a couple of endemic species in south Somalia and south Ethiopia. The same is also true for the northern part of the western region, African i.e., the basins some of Pleistocene the during events drying severe the suffered Niger and Senegal that 20,000 years ago. In southern uctuations Africa, during severe the climate fl Pleistocene made this region inhospitable for Afrotropical prosobranchs, so there are no restricted range species with the exception of species within the genera Figure 4.5. The distribution of restricted range mollusc species in mainland continental Africa, showing showing Africa, continental mainland in species range mollusc of restricted distribution 4.5. The Figure per river/ = number of species Species richness Lakes. and the Rift Valley Maghreb of diversity in the hotspots lake sub-catchment. IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 107 IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 108 108 CHAPTER 4 | MOLLUSCS s o te ais pae o ape, ay r habitat are many sample), to place easiest the not is Matadi near rapids of stretch (the locality type the than larger be must range true their areWhile overlooked. easily which Bithyniidae, and Assimineidae Hydrobiidae, families the to belonging species sized small for case the only locality.is type This the from known only are Congo) the of Republic Matadi, near Ango-Ango at River Congo and Liberia, Soapiti, near River monotypic genera (e.g., even and species of number a Mozambique, to Somalia as well along the coast of the Indian Ocean from southern Congo, the of Republic the to d’Ivoire Côte from coast, Atlantic Africa’s along marshes and basins river small In status. Speciesrichness=numberofspeciesperriver/lakesub-catchment. research, field survey, andinformationonrelevant threats inorder tomakeanassessmentoftheirconservation of speciesinthecentresAfricarequire ofdiversityintheAfricanlakesandnorthern additionaltaxonomic Figure 4.6.Distributionofthefreshwater molluscs assessedasDataDeficient, showingthatlargenumbers Soapitia dageti in the in mauritii Valvatorbis from the Konkouré deep, meromictic lakes like Lakes Tanganyika and Malawi, In time. of period short a within impact can it which over exercise, as this depends on the level of threat and the area easy an notAdmittedly, not.is didit otherswhile lake, rift whole a impact and throughout spread to likely threats consideringsomelakes,all criteria for same the apply not (Darwall Africanregioneasternthe molluscs of thereport theon In Finally, there are the endemics of the large Rift Valley lakes. also beenassessedasthreatened. therefore, have, species These rapids. in stones as such confispecialists specifia to ned extent, limited of habitat c 2005), the original assessorsoriginalapparentlythedid 2005), al. et 4/3/11 18:38:20 CHAPTER 4 | MOLLUSCS 109 4/3/11 18:38:22

Burnupia and Ferrissia 4.2.3 Data Defi cient species 4.2.3 Data Defi ciency in molluscs are The two main reasons for Data Defi taxonomic uncertainty and poor geographic knowledge. The regions with the cient highest proportion of Data Defi species are northern Africa, the east African Lakes, and western 4.6). Africa (Figure In southern Africa, taxonomic issues relating to a number genera the in species limpet small of ed classifi being species these behind reasons main the are as Data cient. Defi This contrasts with where westernthere is little Africa, recent survey data available and, as cient due ed as Data such, Defi more species were identifi to lack of recent data on distributions (Figure 4.6). In the knowledge regions, African southern and western eastern, is, in general, reasonable due to surveys conducted the second half in of the 20th funded century, by the World Health Authority (WHO) to study African freshwater snails and schistosomiasis of transmission the in role a play that other parasites. As no schistosomiasis occurs in northern Africa, this region was not incorporated in the research campaigns funded by WHO, and there are subsequently a higher number of species listed cient as due Data Defi to a lack of distributional data. In northern Africa, the high molluscs freshwater the within disarray taxonomic of level described being species many of consequence a largely is by members of the 19th century “Ecole French Nouvelle”, © DANIEL GRAF AND KEVIN CUMMINGS L. solidus) are considered et al. 2009b). Such species have been Bellamya phthinotropis, which is as reported only Lanistes nyassanus and assessed assessed as threatened. For other endemics, Gabbiella such as humerosa alberti of Lake of Endangered Albert, may need the re-evaluation during status the available. becomes information next more as assessment as as Endangered, but poor quality of data available at the time of assessment may require be revised. the Ongoing assessments investigations to leading to knowledge of a the real better distribution ranges of populations in these lakes will soon be available. The same is true for information current where lakes of other prosobranchs the lakes, within distributions restricted have to species shows such as being found in the south-west part of Lake Victoria, and recovered been only has which neothaumiformis , Gabbiella from a very area restricted in the south-west part of Lake Chad (Kristensen the benthic fauna is confi ned to a small oxygen-rich stretch stretch oxygen-rich small a to ned confi is fauna benthic the close to the coast (upper 80m in Lake Malawi, and upper hypoxic or anoxic the In Tanganyika). Lake in 200m to 100 zones there is no macro-life. Barring a few all exceptions, Lake Tanganyika endemics have been assessed not as threatened (Least Concern, cient Data or Defi Near Threatened) as many, whilst range-restricted, occur in a greater number of locations than meets the threshold for a threatened category, given the Lake some localized contrast, nature In zone. of sublittoral the lake’s the to threats the sublittoral found though throughout endemics, Malawi (e.g., Diving for mussels in the Upper Chambeshi River, Upper Congo. River, Diving for mussels in the Upper Chambeshi IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 109 IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 110 110 CHAPTER 4 | MOLLUSCS Table 4.4.ExtinctmolluscspeciesinAfrica. itiuin pten ad h ipcs f threatening of impacts activities. the and patterns distributions extensive fi eld survey in order to requirebetter understand regions species These conducted. been has work survey with a long history of confl icts, have large areas where little all Mozambique, and Angola Africa, southern in countries only a few malacologists ventured into 1930 the beforeregion. Similarly, even and 1930, since Somalia for available data no a virtually are there example, For for areas. of number knowledge available the limited also have unrest political to due countries some accessing Diffi in culties Defi cient. Data as recorded also are only, islands Eritrean the from described were which of some species, mangrove many made to re-examine been it since the havelate 19th century. efforts As such, no apparently but rich, quite is fauna water brackish the contrast, by However, region. the in no effort virtually survey little been has has there hence Eritrea and freshwater, attention. little received have Somalia Eritrearegionsand of the Africa, north-eastern In also includedintheWHOcampaigns. Defi relativelyis species cient low, werecountries these as Data of number the Sudan and Ethiopia Egypt, In work. outstanding some do to starting are who emerged has changing as a new generation of gradually Maghrebian is malacologists situation This period. that since populations and we still lack suffi cient information on the status of their validity, taxonomic their to as doubt remains there 1920, for quite a number of species described between recentFew revisionstaxonomic that, so made, been have name. species different a given were variants all where Bithyniidae Family Bithyniidae Hydrobiidae Hydrobiidae Hydrobiidae Hydrobiidae Hydrobiidae Hydrobiidae Hydrobiidae Hydrobiidae Hydrobiidae Hydrobiidae Hydrobiidae Hydrobiidae Hydrobiidae Hydrobiidae Genus Bithynia Bithynia Bythinella Bythinella Bythinella Bythinella Hydrobia Mercuria Pseudamnicola Pseudamnicola Pseudamnicola Pseudamnicola Pseudamnicola Pseudamnicola Pseudamnicola Pseudamnicola ca 1850- Species tentaculata leachii limnopsis mauritanica microcochlia punica gracilis letourneuxiana doumeti globulina barratei desertorum oudrefi ca ragia latasteana singularis fi eld surveys are required before this can be confi rmed. from South Africa, may be already Extinct, but and more extensive (herekadeii listed asCritically Endangered) from Cameroon that some of the central African species, such as probable is it though Extinct, as listed prosobranchs no are there Africa of rest the In Africa. Mediterranean in localities beenlostfromsouthernfewthetheir edges ranges a of in have that Minor Asia and Europe throughout found still species Palaearctic widespread are These Africa. northern to restricted also are gastropods Extinct Regionally The two or three times the number cited above. be could they known; be never will speciesextirpated of number reviewtrue to the possible that such taxonomy the longer no was it so locations, many at already disturbed or were lost springs freshwater and sources water the 1970s the in sites the re-investigate to tried (1976) Boeters lumped in the 19th century. By the time researchers such as higher, as this subterranean malacofauna was taxonomically out. The number of extirpated species may be considerably drying springs many to led has which aquifers, underlying and springs the from water of over-abstraction the and species have suffered from a combination of waterThese sources. pollutionthermal or wellssprings, two or one only arehydrobidthat range-restricted,in small snailsoccurring Extinct(Tablebe proportion high regionaof This4.4). has to considered are species 14 Tunisia), where and Algeria lie in the Maghreb region of north-western Africa (Morocco, in Africa south of the Sahara, but most confi rmed Thereextinctionsare fewa possible extinctions orregional extinctions 4.2.4 Extinctionpatterns Tomichiacawstoni (also listed as Critically Endangered) IUCN Status Regionally Extinct Regionally Extinct Extinct Extinct Extinct Extinct Extinct Extinct Extinct Extinct Extinct Extinct Extinct Extinct Extinct Extinct Potadoma 4/3/11 18:38:24 CHAPTER 4 | MOLLUSCS 111 4/3/11 18:38:25 VU VU EN EN EN EN EN EN CR CR CR CR CR CR et al. (2003) RL Category et al. 2010). In Lake Probably LC Probably threats threats threats threats species along the lake lake the along species Lavigeria et al. (2004) and West DDDDDD Uncertain range extent; DD? LC Probably DD LC Probably DDDD Uncertain range extent and LC Probably DDDD LC Probably LC Probably DDDDDD LC Probably LC Probably DD Limited range, but uncertain Limited range, but uncertain DD LC Probably DD LC Probably DD LC Probably DD LC Probably RL Category Possible Status subsp. nov. ‘boulanouari’ subsp. nov.

subsp. nov. ‘taramtensis’ subsp. nov.

Subspecies report many new possible new many report Tanganyika, Tanganyika, Michel margins. Many of these appear to be quite widespread, and hence, when formally described, will assessed probably as be Least Concern. However, possibly at four, of least these undescribed three, taxa have a limited range, and once rmed confi as ed as valid classifi threatened by species sedimentation may and pollution be urban areas. adjacent from are are found have been severely depleted through habitat and habitat through loss of due water, to over-abstraction degradation resulting from pollution and saline intrusions into their groundwaters Damme (Van andraea sp. nov. ‘wiwanensis’ sp. nov. sp. nov. ‘mirlheftensis’ sp. nov. sp. nov. ‘haasei’ sp. nov. sp. nov. ‘aghbalensis’ sp. nov. sp. nov. ‘salahi’ sp. nov. sp. nov. ‘boulali’ sp. nov. sp. nov. ‘meskiensis’ sp. nov. aponensis sp. nov. ‘makhfamanensis’ sp. nov. sp. nov. ‘kerdouensis’ sp. nov. sp. nov. ‘valai’ sp. nov. sp. nov. ‘tiznitensis’ sp. nov. sp. nov. ‘ramdanii’ sp. nov. sp. J et al. (2003) p. 41-2 West sp. F et al. (2003) p. 52 West sp. T et al. (2003) p. 56-7 West sp. S et al. (2003) p. 56 West sp. P et al. (2003) p. 45-6 West sp. K et al. (2003) p. 42 West sp. R et al. (2003) p. 49 West sp. B et al. (2003) p. 55 West sp. D et al. (2003) p. 53-4 West sp. N et al. (2003) p. 47 West sp. H et al. (2003) p. 54 West sp. C et al. (2003) p. 51 West sp. Q et al. (2003) p. 46 West sp. O et al. (2003) p. 43 West sp. G et al. (2003) p. 50 West sp. M et al. (2003) p. 52 West Lavigeria Lavigeria Lavigeria Lavigeria Lavigeria Lavigeria Lavigeria Lavigeria Lavigeria Lavigeria Lavigeria Lavigeria Lavigeria Lavigeria Lavigeria Lavigeria Heideella Belgrandia Mercuria Horatia Horatia Heideella Heideella Giustia Semisalsa Heideella Heideella Heideella Bythinella Belgrandiella Hydrobiidae Hydrobiidae Hydrobiidae Hydrobiidae Hydrobiidae Hydrobiidae Paludomidae Paludomidae Hydrobiidae Paludomidae Hydrobiidae Paludomidae Paludomidae Hydrobiidae Paludomidae Paludomidae Hydrobiidae Paludomidae Paludomidae Paludomidae Paludomidae Paludomidae Hydrobiidae Paludomidae Hydrobiidae Paludomidae Paludomidae Hydrobiidae FamilyPaludomidae Genus Species Source FamilyHydrobiidae Genus Species These are all species that have been listed in books or PhD. theses but are yet to be formally described, so are not yet placed on the not so are yet to be formally described, all species that have been listed in books or PhD. theses but are These are IUCN Red List. 4.2.5 Undescribed species There are some recognized species in northern Africa and Lake Tanganyika been that described have which extinction not (Table are 4.5). These yet clearly species require formally formal descriptions threatenedin order to be included in the with IUCN Red List. Other species that have yet to be existdescribed inalso Africa, and have (Table 4.6). yet to be fully investigated Most of these are range-restricted species known from northern Africa, where the water sources in which they Table 4.5. Undescribed threatened freshwater molluscs endemic to Africa. endemic molluscs freshwater threatened Undescribed 4.5. Table Table 4.6. Undescribed Data Defi to Africa. molluscs endemic cient freshwater 4.6. Undescribed Data Defi Table IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 111 IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 112 112 CHAPTER 4 | MOLLUSCS of BurkinaFaso. Pollution of a small river close to Ouagadougou, the capital ciiy n h cthet ue f olsiie, n the and molluscicides, of use catchment, the in activity agricultural from sedimentation of levels increased to due Africa, threatsIn eastern from declining habitat quality are species facingthesecombinedthreats. outambensis (CR) and temperature. water increased and fl regimes ow combination of water pollution, sedimentation, altered river the through Guinea, and d’Ivoire Côte Leone, Sierra from This impacts a number of restricted range and endemic species mining bauxite flgeneration. river power hydro-electricdamming for ows of expansion plantations, pesticides crop of in use extensive the of result a as primarily declining is rivers in quality habitat the Africa, western In increased frequency ofdrought. referscase largelythis the in to which disasters”, “natural by threatenedof species. Finally, somespecies arethreatened 5% than fewer signififor a threat as cant recorded only are they but species, some on impact an had have and present are species mollusc Invasive mollusc. of species native on invasive species do not appear to have had a notable impact andBrown 1999). Incontrast toother taxa, such asfi shes, gastropod species, which are vectors of bilharzia (Kristiansen from the direct impacts from region to region. A number of species are also suffering threatened species, of but again, 63% the impacts sources which of threat, the major pollution another vary is sources of range explained below.regions, pollutiona Water as from throughout Africa, the causes widespread of is habitat problem decline this Although consequences. vary thebetween suffering species threatened and of 58% dams) withdeforestation, (e.g., development infrastructure expansion, agricultural as such actions multiple through degradation, 4.7).mostThesignifi thesecantthreatsof habitat isloss or threats that combine to lead to declining populations of series a (Figureusually is there cases of majority the In Africa. in molluscs freshwater to threats of sources multiple areThere ofthreat4.3.1 Regionalpatterns 4.3 Mainthreats © TIMOMORITZ Soapitia dageti (CR) are two notable of molluscicides employed to reduce Sierraia © TIMOMORITZ Newly built dam for irrigation, south-west Burkina Faso. (Van Dammeetal.2010). ecology local the on impacts subsequent with Delta Nile the reduced fl ow of the Nile has the resulted in a retreat of the leaving and quality habitats in aquifers unsuitable for many species. In Egypt, water the changing systems, underground karstic the into seawater of intrusion the in resultedhas aquifers fromthe extraction water endemics, hydrobid underground numerous its with In Maghreb, highest. the are exploitation agricultural and expansion urban where lowlands, the in particularly disappearing, (Van environment the Damme of capacity carrying ecological the overreached far by has growth and demographic where fertile, and green relatively is which region African clearly observed in the Mediterranean part of the northern Damme (Vanpesticides and fertilizers detergents,chemical of use significommon now the of result a as cases many in cant, quite often is pollution water populated, sparsely are that Damme (Van untreated and polluted heavily are that waters of return subsequent the and use, agricultural and industrial domestic, for waters the of result a as declined has quality habitat Africa, northern In molluscicides (Kristiansenetal.2009a). of use and Africa, southern in mining dune waste, mining pollution fromsources,industrial and domestic fromsedimentation water irrigation, for water of over-abstraction with dam construction for hydro-electric power generation, In southern Africa, the decline in habitat quality is associated the nativespecies. of levels population the on impacts long-term have could molluscivores or omnivores, whose predation on molluscs are which fiof introduced many with species, stocked sh the and Victoria Lake 2005). (McIntyre Tanganyika Lake in organisms benthic most impact to recognised is sedimentation increased of impact the molluscs, on sedimentation of impact the on specifino arethere yet, as Although, Perch. Nile and studies c hyacinth water as such species invasive of impact vrasrcin f ufc ad underground and surface of over-abstraction 00. h ms daai efcs a be can effects dramatic most The 2010). al. et 00. n hs ra seis r rapidly are species area, this In 2010). al. et 2010). Even in regions in Even 2010). al. et tipa lks ae been have lakes Ethiopian t al. et

4/3/11 18:38:27 CHAPTER 4 | MOLLUSCS 113 4/3/11 18:38:32 (2010) reported that the gastropod fauna gastropod the that reported (2010) al. et Cut off upstream populations; downstream populations of molluscs Lead to a loss of from the underlying riverine habitats and their fauna; of part where dam, the of downstream changes Cause uctuations in water level plus the river is impacted by fl changing water-chemistry and water temperatures, potentially impacting life-cycles success; and patterns and reproductive through reproductive changing Cause a loss success. of mussel reproductive changing freshwater sh-host fi movement, potentially

uniformly negative nor positive (Seddon 2000). Dams and form insurmountable barriers that will: their reservoirs a) b) c) d) example, For construction. cial benefi of examples are There Damme Van of the Nile of downstream the Aswan Dam seems to have although improved, this might alternatively be an of effect as molluscicides, of amounts huge of use the in cessation employed during the anti-bilharzia campaigns. According also have populations prosobranch large (1994), Brown to developed in the man-made Lake Kariba, but that seems to be an exception. In contrast, after the construction of number the in increase an was there Ghana, in Volga Lake of bilharzia-carrying species, and a corresponding loss of the native pulmonate species (Seddon 2000), with an overall decline in species diversity and species richness. In general, data from Europe and North America indicate biodiversity loss following dam construction, with the In tropical western and central Africa, the major threat is by shaded streams clear of alteration ow fl and siltation the gallery forest, often resulting in open waters coloured red from laterite muds during the rainy season. Pollution by is as region, this in threat important another is sewage raw swamp of areas forests, gallery clearing After farming. sh fi are often formed that are too wet for raising dangerous cattle. for As a consequence, and in an farming and too introduced has FAO the livelihoods, local diversify to effort existing in sh fi stocking for material provided and methods sh ponds along riverbeds. lakes as well as in man-made fi Such actions have which changed is the now ecology, no longer suitable for many of the endemic prosobranchs. 4.3.2 Dams In North America, dam construction 1900s led during to the severe early declines faunas in (Bogan 1993, 2008), and similar the patterns are now native molluscan beginning to be seen on other continents. In Africa, large dams are already constructed or proposed for many of the river catchments, to generate electricity for industrial already are dams these of impacts The use. domestic and being seen for a number of species, this and development is the set to scale expand of greatly over the next few years (Economic Commission for Africa 2003). Dam construction can impact freshwater molluscs in different animal, the of strategy life-history the on depending ways, making the impact of the construction of dams neither Figure 4.7. Principal threats to freshwater molluscs in mainland continental Africa. continental in mainland molluscs freshwater to threats 4.7. Principal Figure IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 113 IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 114 114 CHAPTER 4 | MOLLUSCS alterationthemicrohabitatsof required somebyfreshwater lakes,a major threat to molluscs is siltation and subsequent tropicalIn western andcentral AfricatheEast andinAfrica 4.3.4 Sedimentation detergents, chemical fertilizers and pesticides. of is use common now the pollution dramatic of because quite often water populated, sparsely are that regions in Tanganyika. Even Lake on Kigoma to close bays River,and Congo the on Kinshasa and Brazzaville of downstream distinctimpactsrangerestrictedon example,speciesfor– had have these areas some In waters. local or downstream dischargeddirectly backintoriverslakes,and polluting the InmostAfrica. cases, domestic waste water andsewage of is parts many in problem a also is sewage Raw2009b). as some and suchtuberculatus species opportunistic of exception C) (García (CR) dageti Soapitia as such Africa, western to restricted are which genera in those are species these of notable most The temperature. water increased and regime miningwastesedimentation,and alongwithchanging fl ow Côted’Ivoire andGuinea are impacted combinationbya of Leone, Sierra from species endemic range restricted Some mining. bauxite of expansion the to due declining is rivers in variable. however,quite are, decline habitat of causes The Africa. throughout problem a is lakes and rivers freshwater in quality habitat in Decline 4.3.3 Water pollution species (Grafetal. 2011). these impact may quality flwater water and of ow patterns impacts on the high diversity signifi havehotspots, may volume) cantas this any 1.2, section changes III (see Ingadamsto the and Inga Grand the for plans Africa, central In decline, increasing thealkalinityinlake. levels water if Extinct become rapidly may it but Concern, Least as assessed currently is and densities, vast in occurs endemic. an also probably is sp.”, “Tomichiaas to referred species, second a and lake, this to species, described One one. impoverished strongly a albeit fauna, gastropod a harbours which is the most alkaline of the African Great Lakes that still Turkana, Lake reaching water of amount the decrease will The planned Gibe III Dam on the Lower Omo River in Ethiopia is notalsothecaseinAfrica. (Pyron USA the in populations gastropod of extirpation local the of reservoir particular in reservoirs, from alterations hydrological generally that is assumed it but out, carried been yet faunas not gastropod have Africa on in construction dam of effects the of appear to be transported by birds (Van Damme 1984). Studies et al. 2008), and there is no reason to suspect that this release, are one of the two main causes causes main two the of one are release, Gabbiella C) and (CR) outambensis Sierraia Inwestern Africa, water quality 00 Kristiansen 2010; al. et , is endemic endemic is rosea, Gabbiella and presently presently rosea Gabbiella Hydrobia species that that species Melanoides Melanoides t al. et

and three, further a and Africa, in and acuta Physa species, Four Asia. or America South in originated species these of Eleven pulmonates. three prosobranchs fi and two families,to ve beendecades, belonging two past the within Africa havereported in species gastropod alien Fourteen impacts. pose moment, localized the have do at but signifi Africa not, across problems cant do species mollusc Invasive 4.3.7 Invasive species – molluscs and their impact on impact on the mollusc fauna is yet to be evaluated. aquaculture as an alternative source of income, but again theAfrica has led tochanges inland use, and the expansion of gallerywesternstreamsforestriversalongofcoverandin that have confi rmed this. As mentioned above, the clearance thesein habitats, although there havenot been any studies nativemolluscsthe impacton anpossiblyAfrica, hadhas western fi in farming of development sh the andVictoria, fi Lake various in the farmed Africa, sh eastern of lakes tarn upper the in trout fias non-native such of sh, stocking The 4.3.6 Invasivespecies–fish farming snails (Bulinusspp.andBiomphalariaspp.)inLakeVictoria. also led to an increase in the abundance of bilharzia-carrying comm.) noted that the increase in invasive and weed species spp. has (Bulinus snails areknownincrease to habitat available native bilharzia-carryingto the evaluated, they been not has on general infl in faunamolluscan uence their Although Africa. in problems southern economic and environmental major present (e.g., weeds highlyinvasiveHerbertandalienaquatic(1998)thatnoted 4.3.5 Invasive species–waterhyacinthandotherplants extreme to fl change the uctuations tolerate in diurnal not dissolved do oxygen that levels. prosobranchs dwelling bottom the problemsfor causes it but prosobranchspecies, growth, which may benefi t most pulmonates and plant aquatic favour some alsodecreasing velocities stream willsmall sediments foul their gills. Increased exposure to sunlight and the and stones, these fifi cover in and that mud silts increase of ne lms an is there as impacted also are waters forest Prosobranchs adapted to life on hard surfaces in swift running fi levels. of oxygen quantities depleted and muds organic ne chemical characteristics of the sediments through increased and physical the accumulations change These rivers. the in accumulate nutrient-enriched cover, rapidlyforest soils species).riverclearedbanksWhenMelanoides aretheirof of the bottom sediment, or they live within the sediment (e.g.,are benthic or epibenthic, tracing furrows through the surface snails. Most African prosobranch species (unlike pulmonates) Gyraulus chinensis , could potentially become so, as they indigenous species and stratiotes Pistia Thiara granifera, Pseudosuccinea columella, columella, Pseudosuccinea granifera, Thiara have becomeinvasivehave marmorata Aplexa p.. ag (pers. Lange spp.). Biomphalaria Pomacea difusa, R. rubiginosa R. difusa, Pomacea ihona crassipes) Eichhornia

4/3/11 18:38:33 CHAPTER 4 | MOLLUSCS 115 4/3/11 18:38:36

T. et 2010) of et al. probably probably has the is present present is granifera T. et al. 2009). Although at some sites. Another Tarebia Tarebia granifera, M. tuberculatus et al. 2004). The characteristic pattern Tarebia Tarebia granifera is often regarded as T. granifera T. over pulmonates and may be the on the indigenous gastropods of T. granifera gastropods on the indigenous . unpublished data). Where Where data). unpublished al. et et al. it making 2000), that its unlikely introduction Melanoides tuberculatus, the native forms are being falls within the wide range of characters M. of the tuberculatus range characters wide within falls has displaced the indigenous form in Lake Lake in form indigenous the displaced has tuberculatus M. these these are species that should be monitored. It may be that long not have in been Africa or some all of invasives these as the as extirpations serious to had have impacts enough as Caribbean the such of world, the done parts in other reported research to made be to has recourse unlikely is Inevitably, it islands. here even but elsewhere, invasives same these on to islands suchthat observations in, for example, small tropical directly extrapolated be can Martinique and Rico Puerto as coming however, is, information quantitative Valuable Africa. from ongoing N.A.F study Miranda’s (Miranda the impact of the coastal lakes of northernAfrica. KwaZulu-Natal, South and changes major caused have species introduced Some impact on native species, whereas others aren’t known to have had cant any impact. signifi In some cases, as such displaced by the south-east Asian morph. For example, Malawi Lake invaded has morph Asian south-east the where it has displaced the indigenous form in the southern parts of the lake (Genner morph invasive of this sculpture and ornamentation of shell of seen in the polymorphic indigenous Samadi form morph invasive (Brown the as Just 1994; noticed. easily be will spread and of in happened have also may it that evidence is there Malawi, Africa, South province, KwaZulu-Natal in and Africa western years. recent in Another parthenogenetic south-east Asian thiarid species in the family Thiaridae, granifera has allowed it to invade several estuaries, lagoons and coastal lake systems in KwaZulu-Natal (Miranda in large numbers, it is likely to as it have consuming does a substantial on production, primary an the important explain may impact which resource, food available the of portion dominance of cause of the loss of greatest potential of any invasive species to threaten native native to threaten species invasive of any potential greatest species. Following its discovery in of South provinces Africa the in through 1999, rapidly spread has granifera Tarebia KwaZulu-Natal and Mpumalanga, as well as Swaziland (de Kock and Wolmarans 2008; Appleton it is currently also moving southwards towards the Eastern Cape, its spread is and northwards, predominantly it will rivers undoubtedly northernmost reach three Mozambique the and fact, In Zimbabwe so. soon done if already it not has in which it has been found reason no seems (Pongolo, There Sand Mozambique. and southern Crocodile)into ow fl all eastern into northwards spreading continue not should it why and central Africa. The high salinity tolerance exhibited by al. 2010). Although a detritivore, its diet includes large productivitybenthic primary daily of 68% to up – microalgae quantities of benthic (Miranda Marisa Melanoides and Bulinus spp.. Pomacea spp. and Tarebia Tarebia granifera, have been , has been recorded recorded been has uminea, fl Corbicula Biomphalaria spp. © DANIEL GRAF AND KEVIN CUMMINGS Danger crocodiles! Field survey has to be conducted with care! are invasives in other countries. The other thiarid, other The countries. other in invasives are species the of morph invasive an represent may tuberculatus, analysis. DNA by rmed confi be to needs this but Asia, from seem introduced as reported been have that species Several not to have survived. Only one alien freshwater bivalve, the clam Asian introduced Damme et al. 2010a). in African waters (Van tropical in originated Africa in snails freshwater invasive Most or of regions sub-tropical the world and, in terms of their often accidentally, are thermal warm tolerances, (i) water Introductions species. introduced those into divided be also can deliberately, (ii) introduced those and trade, aquarium the via of hosts intermediate the of control biological the for usually on and, schemes water transfer Inter-basin schistosomiasis. a much of scale, smaller may tanker transport water, also distribute freshwater molluscs to new water bodies, as has happened in Namibia (Appleton pers. comm.). Some have invasives been widely across Africa, recorded while others are known from only species, of several a distributions wide the few Despite or countries. even single quantitative information on their impacts on indigenous African molluscs is scarce and often anecdotal. Several species, notably the apple-snails, cornuarietis, and the thiarid of agents schistosomiasis ed biocontrol as potential identifi host snails because they pulmonates such prey as on or compete with Whether this competition is for resources, such as food, or as such food, is for resources, competition this Whether by the facilitated contact) physical (e.g., to due interference case Each clear. not is densities, population greater invasives’ Nevertheless, unique. more-or-less and different be to seems IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 115 IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 116 116 CHAPTER 4 | MOLLUSCS Children washingclothes inasteamneartheSanaga Children River inCameroon,potentiallyexposed todiseases hosted by freshwater molluscs. hosted byfreshwater © KEVINSMITH 4/3/11 18:38:40 CHAPTER 4 | MOLLUSCS 117 4/3/11 18:38:42

and 2005). al. et Biomphalaria S. intercalatum, S. © CHRIS APPLETON S. mansoni (cause of Physa acuta also were infections haematobium S. Lanistes carinatus in Egypt, Schistsoma haematobium (cause S. mansoni, or both, in sub-Saharan Bulinus as well as the invasive Approximately 300,000 Approximately people are estimated to die each year from the disease (Hotez and Fenwick 2009), mostly of case the in failure kidney from infections. and haematosis in the case of S. mansoni cult is diffi schistosomiasis of human impact economic The to gauge in monetary terms accurately because measuring of culties the in diffi effects of subtle variables absenteeism, like loss of productivity and reduced educability costs Certainly, scale. national even or continent-wide a on year. per dollars US of millions of hundreds into run Africa to DALY the is morbidity of measure alternative used widely A affects affects people in parts of western Africa, and also uses species of Bulinus as its snail host. either with infected children, mostly people, of number The S. haematobium or 600 another with 170 million, at around is estimated Africa Southgate 2002; (WHO infection of risk at million Biomphalaria (Gastropoda: Planorbidae), respectively, as parasite, human third A hosts. intermediate (LC), a widespread species in southern Bulinus tropicus Africa and beyond is known to act as the intermediate , a microbothrium uke Calicophoron host for the conical fl common parasite of domestic animals. Within the genus Bulinus is found the intermediate host species for urinary schistosomiasis, a serious human disease. and susceptible to infection. Schistosomiasis Human occurs in schistosomiasis every country in Africa, decades early the since known been has It Lesotho. except of the 20th century that the life-cycles of the two important schistosomes, most of urogenital schistosomiasis) and intestinal schistosomiasis), involve species of Bulinus central central nervous system and cause eosinophilic meningitis. reports isolated parasite, an Asian predominantly Although from northern, western and southern Africa suggest that (1978) in may Ibrahim have Africa become widespread angiostrongyliasis and Yousif and (1975) Lämmler and Yousif too. reported natural infections in and showed experimentally that species of are Iridinidae) spp.). This factor factor This spp.). Neritina . However, pea- However, granifera. T. et al. 38 (1981) recovered types Pisidium) are common in shallow is sediment disturbance, as as disturbance, sediment is granifera T. , but when people ingest ingest A. people cantonensis, when but is worrying, since it will surely surely will it since worrying, is granifera T. spp. and spp. Septaria . Rats are the usual usual the Angiostrongylus are cantonensis. Rats molluscs on human health and and health human on molluscs livelihoods may become more signifi cant in the as future, invasions by may become signifi more reductions great in resulted have to documented are thiarids in numbers or, in some cases, the extirpation of several indigenous gastropods and bivalves in several Caribbean et al. 2009). islands and the USA (Pointier 1999; Karatayev 4.3.8 Climate change directly be to known are molluscs freshwater few present At by climate change. In most threatened cases, an increased frequency of drought events will be a secondary problems, threat toalready are there where species freshwater these such as in levels over-abstraction water low to leading of are that purposes, agricultural water for domestic springs. and and rivers the in of levels Lake Chad the water decline In Africa, western leading the 1970s, since and ongoing consistent has been to the reduction in the size of the lake. This has led to the listing of four endemic taxa within a threatened category, of need in all are taxa these above, mentioned as although, rm their status as full species. to confi taxonomic review disruption caused by caused disruption sediment the through way its ploughs that snail active an is it deep as millimetres several it “trails” leaving does so. The freshwater mussels (families Unionidae and 4.4 Understanding the impact of of impact the Understanding 4.4 parasites for hosts The intermediate economic importance of as African freshwater molluscs roles their on primarily rests serve They stock. domestic and people in disease causing ukes. fl trematode of variety wide a for hosts intermediate as distinguishable morphologically 112 reported (1938) Porter across from species mollusc 28 in trematode larval of types South Africa, while Loker in 14 mollusc species from the Mwanza region of Tanzania. of Tanzania. the in Mwanza region 14 mollusc species from important economically cause trematodes these of Several causingthose with stock, domestic and people in diseases schistosomiasis and fascioliasis by far the most important. for the hosts as intermediate serve snails freshwater Many nematode nitive hosts for defi its larvae, either by eating infected snails or in mucus trails trails or in mucus snails infected by eating either larvae, its left by infected snails on salad material, they penetrate the endanger the prosobranch community there (including the (including there community the endanger prosobranch of species rarer unlikely to be severely affected, since they occur mostly in mostly occur they since affected, to be severely unlikely by favoured is than deeper water clams (Sphaerium and water and could be exposed to impact. The the invasion of brackish water zone along the by Africa south-east of coast and east IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 117 IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 118 118 CHAPTER 4 | MOLLUSCS h cuty ms i te ie et, ih rvlne up prevalences with Delta, Nile the in most country, the in infected be to thought are people 830,000 estimated An Egypt where fascioliasis is regarded as an emerging disease. Human fascioliasis inAfricaneedsinvestigation. F. hepatica and both to susceptible is Africa, in invasive is which columella, American North the that shown have elsewhere Studies sub-Saharan in and Africa, fasciolid common most the gigantica, flliver fascioliasis; cause that ukes Zambia. specimensafterafiPreserving atLakeBangweulu, eld survey pce of Species Fascioliasis are more susceptiblethancattle. Sheep recorded. been have mortality and morbidity signifi bycant accompanied outbreaks Localized areas. some in 90% to up of cattle inprevalence with death, in (Brown resultmay margrebowiei infections S. Heavy 1994). widely less other three species, veterinary distributed do as hosts, intermediate as Both veterinary schistosomes are widespread over the continent. mattheei. schistosomes ungulate the to due is mostly and common, also is schistosomiasis Veterinary (Hotez andFenwick2009). malariaortuberculosis, andalmost equivalent toHIV/AIDS in Africa are as high as 70 million – more than losses due to death. years lost to a disease due to morbidity, disability and early (disability-adjusted life year), which measures the number of . bovis S. Recent estimates of DALYs lost to schistosomiasisDALYstoestimatesof Recent lost Fasciola infections are uncommon in Africa, except in © DANIELGRAFANDKEVINCUMMINGS ie h cmo hmn aaie, these parasites, human common the Like for truncatula L. Lymnaea F. gigantica, and s seis of species use mattheei S. ev a itreit hss o the for hosts intermediate as serve

so its role in the transmission of F.hepatica S. curassoni, S. for natalensis L. (Mas-Coma2004). and bovis S. and leiperi S. Fasciola Bulinus Bulinus S. L. h vle f hi mlucn idvriy s capacity so biodiversity, molluscan their of value the relevant governments or ecologicalindigenous communities appreciate and value the Rarelydoraised. be to molluscsneedsimportance of the of awareness and Capacity are toprovide effective protection tofreshwater species. entire river and lake systems within their boundaries, include if they to and catchments upper protectspecifi to cally alteredfl and owregimes. sedimentation,Protected areas need species, tobedesigned invasive pollution, as such protected area boundary will not stop the spread of threats theincluded, are they wherecases in and,comm.), pers. as than rather (Darwall,right own markers their inconservationtargetedfeatures boundary as lakes and rivers include areas protected of majority The fauna. freshwater of protection specifi for designed cally areas protected few Sites, Ramsar of exception the with are, there Africa protectedareas conservationas actions forthespecies, in and the spring-snails, have benefi ted from the extension of populationsworld freshwater molluscs, such as the local river rapids species of the of healthpartsother in Whilst1999).Brown (Kristiansen and the improve to schemes of focus the managementbilharzia of part programmeseradicationas being often more attention, conservation little get faunas mollusc freshwater the fact, In Africa. of placeprotectto anytheofthreatened freshwater molluscs in measures conservation targeted known no are There still applyonceadditionaldatahavebeenincluded. would actionssuggested and conclusions theomissions, thethreats tothese species across Africa. Even with these biodiversityandmolluscan of status therepresentative of described, we believe that the data presented arebe tospecies for waitreasonablyunderestimates andwe incurred as Atpresent, despite thefew omissions from ourspecies list 4.5 Recommended conservation diffi cult toassess. more are sheep in Infections areas.fascioliasis-endemic Nevertheless, signifi quantify. economiccantlossesexperiencedare farmersin by to diffi however, cult These are, carcasses. effects underweight and livers condemned to due poor, is animals such of marketability The rates. calving lower andproduction milk lowergrowth, reduced show animals infected chronically and cattle in reported frequently are 50% above Prevalences animals. stock of andknownis across thecontinent where affectsit rangea Animal fascioliasis is more common than the human disease, bladder become infl amed as well. problem in Egypt. In chronic infections the bile duct and gall resultedinthe disease being recognized aspublica health has liverflimmature thethroughthe migrate they as ukes by caused pathology severe The 2008). (Soliman 17% to measures 4/3/11 18:38:44 CHAPTER 4 | MOLLUSCS 119 4/3/11 18:38:46

et al. Ferrissia, as Burnupia is usually hasgranifera Tarebia Burnupia and Ancylus. Most of these species Mutela joubini (Iridinidae) is known et al. (2011) note, in western Africa ecology Field survey for Data Defi cient species Field survey for Data Defi well as a few species of 2011). The decline in native freshwater mussels could also couldmussels freshwater native in decline The 2011). lead to fundamental changes in the river ecosystems, as as well services,ascation purifi waterprovide mussels the (e.g.,musselsthe oncommensallivingspecies forhabitat freshwateracari). Many such studies could besuitable as sources small if projectsstudent MSc. andundergraduate of funding could be provided. iv) Many freshwater molluscs in the region are known from only a relatively small number of specimens, and most of those have not been corroborated by recent collecting. For example, as Graf mussel the freshwater from ve only museum fi lots, mostly in the Basin of the western African Chad-Chari region. As another example, the family Ancylidae belonging to two main genera, is represented by 49 species are assessed as cient, Data awaiting Defi the results of ongoing research by C. Albrecht. As limpets are thesevery small they are likely to freshwaterbe overlooked by collectors in eld, the which fi may explain why they cations are are so currently poorly best known. made Identifi on the basis of proximity to the described species. the Finally, genus type localities of the considered to be indigenous to Africa, but a species of AmericaSouth from ed identifi beenrecently has Burnupia by dos Santos (2003), raising biogeographical questions as to the true distribution of the as genus. these are Species clearly such in need of eld-survey further and conservation informed make to fi order in review taxonomic poorly more the in especially decisions, management and surveyed regions of Africa, such as the smaller lakes in eastern Africa (e.g., Lake Albert), owing the rivers fast-fl in western Africa, and parts of the Congo manybasin of where the least known species were described in the last century. of invasive species v) Control Research to better understand the impacts of where regions in especially species, invasive become established, should be a priority. For many freshwater molluscan taxa in Africa, demographic, Africa, in taxa molluscan freshwater many For ecological and life history data cient are to insuffi make meaningful predictions about how gastropod and bivalve environments. freshwater changing to respond will species parasiticthefor sh example,Forinformation host-fi theon larvae of freshwater mussels of the families Unionidae, Iridinidae and evaluation Etheriidaeof c the impacts specifi of dam construction, are shing or aquaculture overfi on these bivalves minimal, (Graf prohibiting that any proposed developments in these regions take these endemic species. account of Research studies on species demography and iii)

et al. et al. 2008), Decline of food supplies for the other aquatic crabs, native as such molluscs, species these on predate that sh. fi and birds Increase in the carrier species, fi lling the niche Increase in vacated the carrier species, fi by the non-carrier species; and management management

building building projects, such as is ongoing in Morocco (IUCN with and outreach collaboration community 2010) through recommended are departments, sheries and fi wildlife local to raise awareness and and bivalves. of gastropods populations facilitate monitoring of local Environmental Impact Assessments assessments on need the likely impacts developments to proposed to any for mandatory be mollusc should include diversity, and sh to impact mollusc species, such as: dam construction; fi involving extraction timber large-scale developments; farm clear-felling of gallery forests; and mining developments extraction methods. using open surface The use indiscriminate of molluscides needs to be better populations of decline causes also currently it as controlled, threat a provide not do that species endemic non-carrier of to human health or livelihoods. The loss of these species has two major effects: a) 2003). There are also regions in western and central Africa Africa in and central western regions also are There 2003). taxonomic or survey eld fi active little been has there where research since the 1960s, and these regions will be under- recorded and may species. The potentially current estimates of support species diversity may unrecognised well, need therefore, revision over the next 10 years. The lack of “value” placed on c new the community species scientifi has descriptions led to by pressure traditional to than rather publish papers, synthesis or papers overview This, alpha-taxonomy. combined with a decline in journals new of descriptions with dealing papers large take will that new which with speed the slowing undoubtedly is species, described. species are conservation for ow fl information Facilitate ii) It is critical to ensure that information on range-restricted authorities,and relevant the to passed is speciesendemic are less diverse than some continental faunas, the are faunas, less than current diverse some continental number of species is underestimated. There are regions, such as some the north African Maghreb and eastern Africa lakes, where there are many that recognised have species yet to be named (Ghamizi 1998; West Finally, sewage treatment needs to Finally, be improved, and there species invasive of import the on control tighter be to needs the impact on native species. to reduce actions 4.5.1 Recommended research i) Description of new species Although the freshwater molluscs estimated 560 of species (Bogan 2008; Africa, Strong with an b) IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 119 IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 120 120 CHAPTER 4 | SPECIES IN THE SPOTLIGHT I especially totheAfrican openbillstork Freshwater molluscs are important – P.O. Box150,Curepipe, Mauritius ² School ofBiologicalandConservation Sciences,University ofKwaZulu-Natal, Durban,4000South Africa ¹ Photo 1.TheAfricanopenbillstork withitscharacteristic“open”bill. and mussels.Inparticular, itfeeds exclusively onfreshwatersnails The openbillstorkfeedsalmost stork, Anastomuslamelligerus. they aretotheAfricanopenbill we canseeclearlyhowimportant be conserved,butinthisshortessay molluscs areimportantandshould some caseevenwithinit)that conservation community(orin convince peopleoutsideofthe t isnotaneasytaskto Species inthespotlight does abirdusegreatbigbeakto also taken.Thequestionis:how as theAchatinidae,aresometimes (Iridinidae). Terrestrial snails,such wahlbergi andMutelazambesiensis (Unionidae), andChambardia as UniocafferandCoelatura framesi well asunionoidanbivalvessuch on Bellamya spp.(Viviparidae), as and Pilaspp.),lesscommonly family Ampullariidae(Lanistes ovum on largeoperculatesnailsofthe © DAVID ALLAN Appleton, C.C. ¹andLaHaussedeLalouvière,P² shells werefoundonflattened Delta, accumulationsofL. ovum near Chief’sIslandintheOkavango this unresolvedquestion. bills, presentsnewhypotheseson shells withtheshapeofbirds’ comparison ofthedamageto KwaZulu-Natal, SouthAfrica,and floodplain innorth-eastern Delta, Botswana,andthePongolo openbill storksintheOkavango Examination ofshellsdiscardedby on somekindofsolidsurface. always withthepreyresting amongst vegetation,butapparently it isusuallydoneunderwateror and difficult toobservebecause to removethesoftpartsisintricate The processofmanipulatingshells prior toremovingtheirsoftparts. manipulate individualmolluscs like pincersandpickup the tipsofmandiblestooperate shells, butisproposedtoenable thought tobeusedforcrushing for SouthAfricanstorks,isnot the mandibles,5mmonaverage The characteristicgapbetween from theshellsoftheirprey. the birdstoextractsoftparts is theactualtechniqueusedby the subjectofdebate,butsoalso of thegapinstorks’billstill 2006). Not onlyisthefunction 1960; Kahl1971;Hockeyetal. their molluscanprey(e.g.,Huxley in extractingthesoftpartsfrom that theiconic“open” billplays feeding behaviourandtherole reviewed literatureonthestork’s papers onAfricanbirdshave shells? mussels frominsidetheirprotective extract thebodiesofsnailsand On twooccasionsinJuly2000, Various booksandscientific 4/3/11 18:39:25 CHAPTER 4 platforms, approximately 40cm across, made by openbill storks at a height of 30-40cm above the water, in clumps of the reed Vossia

cuspidata (Photo 2). A total of 46 | SPECIES IN THE SPOTLIGHT shells were collected from these platforms, and all were large adults of 40 to 55mm shell height. These shell larders seem analogous to the accumulations of empty shells reported from river banks in eastern Africa, and suggest that the openbill stork reuses the platforms as surfaces for extracting the soft parts from prey snails over a period of time – a sort of kitchen workbench! No bivalves were Photo 3. L. ovum collected from the reed platforms in the Okavango Delta, Botswana, found here, but since they live in showing the triangular notches in the lip of the basal whorl. © CHRIS C. APPLETON deep water, they are inaccessible to the birds. Curiously though, no Pila occidentalis, a second large storks’ lower mandible which is pushes the sharp lower mandible ampullariid occurring in the delta also triangular in cross section. through the notch to sever the (Appleton et al. 2003), were present A comparison of these notches operculum and then the columellar even though they grow to 55mm with the bills of museum specimens muscle, probably in one movement. and form part of the openbill’s diet of the openbill stork suggests The lower mandible of the openbill elsewhere in Africa. that the birds use a sophisticated stork is, in fact, slightly curved, Most shells from these platforms technique to extract the soft parts and Kahl (1971) proposed that this (72%) had a single more-or-less of snails like L. ovum. Having curvature made it easier for the triangular notch in the apertural picked the shell up, and secured bird to sever the snails’ operculum lip 5 to 21mm (mean 15mm) deep it between the tips of its grooved and columellar muscle. Five of the (Photo 3). A further six had shallow upper mandible and the knife-like museum specimens examined had chipping and the remaining seven lower mandible, the stork uses the the lower mandible curved to the showed only slight irregularities to lower mandible to take a triangular right, one to the left, and three the outer lip – not very different notch out of the outer apertural lip were not curved at all. Nevertheless, from empty shells found elsewhere to expose the operculum. Using the this action frees the snail’s soft in the delta. Allowing for uneven upper mandible to hold the snail parts from its shell so that they can breakage of the shell, the shape and fi rmly on a surface like the reed be eaten by the bird. depth of these notches match the platform described above, it then A similar technique is used by openbill storks for bivalves or mussels, but with the difference that bivalve prey is initially held crosswise in the bird’s bill. This allows the stork to chip into the ventral margins of both valves with its lower mandible. It then fl icks the shell into a lengthwise position with its dorsal hinge line lodged in the grooved under surface of the upper mandible (or puts the mussel with its notched valves onto the bank), inserts its lower mandible between the valves via the notch and, starting at the posterior end and drawing it towards the anterior end, severs the two adductor Photo 2. An openbill storks’ larder – a platform in a clump of Vossia cuspidata with muscles as it does so. Once these numerous empty Lanistes ovum shells. © CHRIS C. APPLETON muscles have been cut, the soft 121

IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 121 4/3/11 18:40:31 IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 122 122 CHAPTER 4 | SPECIES IN THE SPOTLIGHT concluded that theopenbillstork Huxley (1960),hadpreviously numbers consumedinthiscase. quantitative datatoestimate the openbill storks,butwehave no on thefloodplain, andiseatenby unpubl. data).L. ovumalsooccurs in 1983(P. la HaussedeLalouvière, counted onthefloodplain’s lakes flocks comprisingalmost450birds floodplain, withanestimated20 openbill storksonthePongolo a substantialpartofthediet suggest thatbivalvesrepresent 591,560 individuals).Thesedata standing cropofCh.wahlbergi(or individuals) and4.6%ofthe crop ofCo. framesi(or27x106 consumed 13.0%ofthestanding We estimatethatopenbillstorks caffer Unio Floodplain inKwaZulu-Natal. Ch. wahlbergionthePongolo standing cropofCo. framesiand predation byopenbillsonthe we haveassessedtheextentof la HaussedeLalouvière(1987), for 1983/4fromAppletonand markers, andbivalvedensitydata to bivalvepreydescribedaboveas (Photos 4candd). taken outoftheposteriorend of bothspecieshadshallowchips 4a-d). Asmallernumberofvalves on thePongolo floodplain (Photos framesi andCh.wahlbergicollected valves ofapproximately60%Co. the ventralmarginsofarticulated present neartheposteriorendsof as deepinL. ovum,werealso shells areremarkablyclean. inner surfacethatthediscarded close totheirscarsontheshell’s These adductormusclesarecutso parts canberemovedandeaten. Near Threatened in SouthAfricatheendemic Various authors,including Using thecharacteristicdamage Triangular notches,seldom in declineworldwide,and Unionoidan bivalvesare isclassified as the valves. umbonal areasandanteriorends of by fragmentsincorporating the bivalves wererepresentedmostly their aperturesintact,while the parts oftheirbasalwhorlbut kept had typicallylosttheirspiresand from thesearchaeologicaldeposits (Appleton 1985).L. ovumshells framesi) andCh.wahlbergi,forfood (probably synonymouswithCo. shells ofL. ovum,Co. mossambicensis people inZambiatoopensimilar the techniqueusedbyIronAge hit withabluntobject,whichwas crushing. Crushingisakintobeing different fromthatresulting damage describedherearequite to doso,butthetypesofshell the gapbetweenitsmandibles crushed theshellsofitspreyusing shallow chipsatthevalves’posteriorends. notches intheposteriorhalfofvalves’ventralmargins,whilecanddshow (b) valvesfromthePongoloRiverfl oodplain. Photosaandbshowcharacteristic Photo 4(a-d).ExamplesofnotchedCo.framesi(a,candd)Ch.wahlbergi (c) (a) © CHRISC.APPLETON important species. the fateoftheseunobtrusive but decisions whichmightdetermine understanding tothosewho make The challengenowistospread this apparent, excepttoaselectfew. in wayswhichmaynotatfirst be is importantafterall,andoften conclusion, thehumblemollusc indigenous achatinidstoo.In snail Helix aspersaandprobably golf coursesforthecommongarden foraging inbuilt-upareasandon range insouthernAfrica,and openbill storksexpandingtheir in birdwatchers’blogsitesof This mayexplainrecentreports mussels’ parasiticlarvalstage. species thatserveashostsforthe invasive fish ontheindigenous molluscides, andtheimpactof increasing pollution,useof Threatened, probablydueto Unio cafferisclassified asNear and inSouthAfricatheendemic bivalves areindeclineworldwide, openbill stork?Unionoidan dependent speciessuchasthe such asthesepotentiallyimpact (b) (d) So howdothreatstomolluscs 4/3/11 18:41:08 CHAPTER 4 Species in the spotlight Can the last populations of the giant | African freshwater pearl mussel be saved? SPECIES IN THE SPOTLIGHT

Ghamizi, M¹ and Van Damme, D²

or decades this large mussel associated to another host, and it was believed to be Extinct, is feared that the same thing will until surveys in the area happen to M. marocana, which may Frediscovered it just a few result in it being lost forever. years ago. Formerly, M. marocana All habitats in Moroccan rivers was considered to be a local race from which populations of M. of the European Margaritifera marocana have been recorded during auricularia, found over a large the early 20th century are heavily part of western Europe. However, degraded, threatened by desiccation a few specialists, such as Dr. Margaritifera marocana (CR) is a large and polluted by domestic and Douglas Smith, disagreed with naiad species endemic to north-west agricultural effl uents. Some this view. But on the basis of shell Morocco. Moroccan types of Margaritifera, characteristics from a handful of such as the one originally described museum specimens collected at as M. dernaica from the Oued Derna, the beginning of the 20th century, gills of their host fi sh, and after are completely gone. Are M. dernaica this taxonomic problem could metamorphosing into a young and M. marocana one and the same not be solved. It was only after mussel, detach and drop to the species? Only in the unlikely event live specimens were rediscovered sediment. This way, the fi sh ensures that live Margaritifera specimens three years ago that DNA research the distribution of the clam. Host would be rediscovered in the Oued by Araujo et al. (2009) provided specifi city in all Margaritifera Derna could this question be solved. the irrefutable evidence for species is high, restricted to a single The conservation of M. marocana, Margaritifera marocana’s specifi c or a few fi sh species. It is not yet considering the recent IUCN distinctiveness. The species is, known which and how many fi sh assessment of its threatened status, hence, a Moroccan endemic, species are used by M. marocana as warrant investigations concerning whose range is restricted to two hosts. If its host specifi city is very not only the biological questions rivers belonging to the same narrow, it may be that the particular already cited above, but should hydrographical basin. The area that fi sh host has disappeared from the also include sociocultural research they occupy within these rivers is rivers where they are known (for on the Amazigh communities that extremely limited. So far, only two example, as a consequence of the reside along the river at the two sites small populations have been found, construction of dams), therefore where Margaritifera still occurs. both at sites strongly affected by preventing reproduction and the Nowadays, local children swim, human activities. Both populations completion of the life cycle of particularly during summer, at consist exclusively of specimens of M. marocana. Virtual complete both sites without paying attention old age-classes, all shells measuring extinction of its main host fi sh, to the mussels, which look like more than 10cm. With no evidence the Atlantic sturgeon, led to the fl attened stones, wearing sandals of juvenile mussels, recruitment extirpation of the European to protect their feet against cuts appears to have been halted, and Margaritifera auricularia except in from the valves’ edges. In 2009, recruitment patterns remain an two rivers where populations are when collecting material for unknown. The same is true for the species So far, only two small of fi sh host or hosts on which the larvae of M. marocana are parasitic. populations have been As with other representatives of the genus Margaritifera, the found, both at sites strongly larvae (of the glochidium type) affected by human activities attach themselves to the skin and

¹ Faculté des Sciences, Marrakech, Morocco ² Faculty of Sciences, Ghent University, Belgium 123

IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 123 4/3/11 18:41:30 IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 124 124 CHAPTER 4 | SPECIES IN THE SPOTLIGHT continued existence. we shouldallbeconcernedfor its species is Critically Endangered and the problemofrecruitment. This species in order to find solutions for our biologicalresearchonthis also equally important to continue conservation ofthespecies,butitis campaigns are set up for the imperative thatawareness swept awayorburiedinsediment. floods, during which mussels are desiccation interrupted by massive that causes periods of drought and precipitation and river flow regime the increasing irregularity of and climate changes, in particular by thedegradationofitshabitat disappearance being hastened presently dyinginsilence,its should discoveranyuseforthem. last remaining populations if they with no hesitation, exploit the two Margaritifera siteswould, that thevillagerslivingnear zone. Yet it should be kept in mind to theinhabitantsofcoastal Morocco seems to be confined oysters and other sea produce in two sites.Consumptionofclams, the villagesinvicinityof freshwater mussels, at least not in appears to be linked to these as well, no culinary tradition tourist cars and buses. Fortunately is also a main stopping point for important siteforthesemussels especially giventhatthemost of pearl), for sale to tourists, with their beautiful nacre (mother shells (up to a length of 20cm), offering these large river pearl relief toseethatnoonewas several occasions,itwasagreat the mussels. the potential commercial value of youngsters werewonderingabout consisted ofEuropeans,thelocal to thefactthatpartofteam about their interest because, due mussels. Thereweremixedfeelings team and helped by diving for enthusiastically joined the research genetic research, these children It is, therefore, not only Margaritifera marocanais On returning to these sites on C inkling of their true distributions inkling oftheirtruedistributions that they exist and have only an of species, we are merely aware mussels in general. For the majority is typicaloftropicalfreshwater know aboutC. wahlbergi,andthis is stillagreatdealthatwedon’t the dry season. However, there to survive the punishment of attributed to the animal’s ability mollusc-hostile continent) can be success of this mollusc (in a truly the continent.Thegeographical recorded frommostregionsacross to particularbasins,C. wahlbergiis have small distributions, restricted mussel speciesintheAfrotropics Africa. Whilst the majority of bit ofmuscle A mollusc with a University of Alabama ¹ mussels. ofAfricanfreshwater relationships study theevolutionary Chambardia wahlbergi, collectedfromafi sheries pond.Thisspecimenwillbeusedto Species inthespotlight species of mollusc in of the most widespread a freshwater mussel, is one hambardia wahlbergi(LC), the African freshwater mussel the Africanfreshwatermussel belongs. Relativetootherregions, family thatChambardiawahlbergi only fromAfrica,anditistothis Iridinidae. The iridinids are known Margaritiferidae, Etheriidae, and families occurinAfrica:Unionidae, in six families. Four of these more than 850 species worldwide dinosaurs, and today there are originated at the same time as the group of bivalve molluscs. They globally distributed,andancient Unionoida belongtoaspecies-rich, environment (includingus). these molluscs interact with their inhibits our understanding of how living musselsinAfrica,andthis detailed fi eld observationsfrom been collected.Itisraretohave based on the places they have Freshwater mussels of the order © DANIELL.GRAF Graf, D.L. ¹

4/3/11 18:41:51 CHAPTER 4 | SPECIES IN THE SPOTLIGHT

The Lutemwe River (Luangwa Basin) in Zambia at low water. © ALEC LINDSAY

fauna is restricted, with only about upon freshwater fi shes. It is very 80 species (compare this to 300 in likely that C. wahlbergi larvae do the North America, or more than 200 same. In 2008 and 2009, with the in south-eastern Asia). Africa is help of Alex Chilala of the Zambian a tough place for molluscs, with Department of Fisheries, it was waters poor in calcium (needed for possible to collect C. wahlbergi from their shells), and the dry climate artifi cial ponds stocked with tilapia. limiting for aquatic organisms. This provides strong evidence that Chambardia wahlbergi ranges the larval mussels had hitchhiked from South Africa north to along with the parental stock Somalia and west to Senegal. In of fi sh, but the dynamics of the southern and eastern Africa, C. reproductive cycle of this mollusc wahlbergi is able to thrive where remain to be explained. other mussels cannot because of To the uninformed, freshwater its ability to survive when rivers mussels like Chambardia wahlbergi dry up seasonally. In 2005, samples may be mere “clams”, but they were taken from the Lutemwe have the potential to capture the River of Zambia. During that time Chambardia wahlbergi, collected from imagination of anyone open to of year, the stream is reduced to a a fi sheries pond. © DANIEL L. GRAF acknowledging the complexity mere trickle, but with the generous and interrelatedness of aquatic assistance of the local people who ecosystems. However, these animals use the subsurface waters for both Unfortunately, most of our are threatened worldwide due to irrigation and laundry, several knowledge of the biology of the degradation of fresh waters. living specimens of C. wahlbergi Chambardia wahlbergi is limited to Basic biological research on the were obtained from deep within such anecdotes. We can only infer freshwater molluscs of Africa will the sediment. With at least 40% its life history from better-studied be crucial for establishing informed of Africa dominated by desert- freshwater mussels, assuming conservation priorities, not only for like habitats, this ability gives C. a great deal from the traits of the protection of biodiversity but wahlbergi, and freshwater mussels temperate species. For example, for the sustainable management of like it, a distinct advantage. almost all mussel larvae are parasitic fresh waters into the future. 125

IUCN AFR2011_pp92-125_chapter 4_molluscs.indd 125 4/3/11 18:42:13