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Bellamya mweruensis

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA MOLLUSCA GASTROPODA ARCHITAENIOGLOSSA VIVIPARIDAE

Scientific Name: Bellamya mweruensis
Species Authority: (Smith, 1893)
Synonym(s):
Viviparus mweruensis Smith, 1893

Assessment Information [top]

Red List Category & Criteria: Critically Endangered C2a(ii) ver 3.1
Year Published: 2010
Date Assessed: 2008-06-05
Assessor(s): Jørgensen, A.
Reviewer(s): Van Damme, D., Seddon, M.B. (Mollusc Red List Authority) & Pollock, C.M. (IUCN Red List Unit)
Justification:
B. mweruensis is endemic to Lake Mweru, where the habitat is shrinking due to the lake drying out. Its extent of occurrence is slightly less than 5,000 km², and the whole population occurs in one location.

In the 1920s, the species was described as much more abundant than it was reported in the 1950s and from more recent collections. Collections in Spring 2006 resulted in only two individuals being collected in two out of 20 collection sites in the lake. Each collection site was approximately 25 km², and from this information it is estimated that there are less than 250 mature individuals in the lake (approximately 200). It is known that the lake is still drying out. Therefore the species is assessed as Critically Endangered.

There is also the possibility that this species may undergo a decline of at least 80% over the next 15 years, given the ongoing decline of this species' habitat. However, there are insufficient data to be confident of this. A future reassessment of this species may take into account further declines and may include criterion A.
History:
1996 Endangered (Baillie and Groombridge 1996)
1996 Endangered

Geographic Range [top]

Range Description: Bellamya mweruensis is endemic to Lake Mweru (Zambia, DRC), where it was most recently recorded at two sites (out of 20 sampling sites in the lake) (A. Jørgensen, pers. comm.).
Countries:
Native:
Congo, The Democratic Republic of the; Zambia
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: No information available regarding population sizes. The species is certainly rare within the lake and seems to be in decline; in the 1920s it was considered much more abundant than it was reported as in the 1950s and from current data.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: It is found in Lake Mweru. Juveniles live buried in sediment.
Systems: Freshwater

Threats [top]

Major Threat(s): In Lake Mweru, sedimentation is occurring as a result of natural processes. Lake Mweru is already very shallow (average 3 m), so it may dry out relatively soon (perhaps within the next 25-50 years). When the lake level reaches 1-2 m, monsoon rains cause extreme mixing of mud and water, resulting in deoxygenation of the lake and the death of species there.

Conservation Actions [top]

Conservation Actions: No conservation measures in place specific for this species. Further surveys and monitoring are essential for this species.

Citation: Jørgensen, A. 2010. Bellamya mweruensis. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 21 December 2014.
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