Pisidium maasseni 

Scope: Global, Europe & Mediterranean
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Mollusca Bivalvia Veneroida Sphaeriidae

Scientific Name: Pisidium maasseni Kuiper, 1987
Taxonomic Notes: Recent molecular studies confirmed the close relationship of this species with the endemic Lake Ohrid pea clam P. edlaueri and the widespread P. nitidum (Schultheiß et al., 2008).

Assessment Information [top]

Red List Category & Criteria: Endangered B1ab(iii) ver 3.1
Year Published: 2010
Date Assessed: 2009-11-30
Assessor(s): Albrecht, C., Hauffe, T. & Schreiber, K.
Reviewer(s): Fehér, Z., Radea, K., Cuttelod, A. & Seddon, M.B.
Pisidium maasseni is small freshwater bivalve is restricted to Lake Prespa, where the range (EOO) is smaller than 500 km2 and where there is a continuing decline in the habitat quality in relation with eutrophication and macrophyte growth affecting the oxygen availability for this species. The extent of the habitat is also shrinking, in particular on the eastern shore and the ecology of the species makes it more sensitive to habitat changes. It is therefore considered as Endangered (EN) B1ab(iii).

This species has also been assessed at the regional level for the 27 member states of the European Union:
This species is restricted to Lake Prespa, with a smaller EOO in Greece (EU27), the range area and the declining quality of habitat would be appropriate for Critically Endangered (CR) B1ab(iii).

Geographic Range [top]

Range Description:Pisidium maasseni is restricted to Prespa Lake, between Albania, FYROM (also known as Macedonia) and Greece (Schultheiss et al., 2008). The total surface area is 254km² and it lies between the three countries with190 km² in FYROM, 84.8 km² in Greece and 38.8 km² in Albania.
Countries occurrence:
Albania; Greece (Greece (mainland)); Macedonia, the former Yugoslav Republic of
Additional data:
Number of Locations:1
Lower depth limit (metres):6
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:This is a locally abundant species in Lake Prespa.
Current Population Trend:Unknown
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:This small bivalve, a pea-clam, is found in freshwater habitats where it is found in littoral zone of the lake on soft substrates.
Continuing decline in area, extent and/or quality of habitat:Yes

Threats [top]

Major Threat(s): The increase of sediment load as the result of erosion of the neighbouring area impacts this small bivalve and its ability to filter water. The eutrophication related to intensive agriculture practice and settlements in the adjacent area to the lake results in the growth of macrophytes, covering the soft substrate and diminishing the oxygen availability within the substrate (anoxic). The introduction of alien fish species for recreational fishing has contributed to profound modification of the natural ecosystem of the lake.

Conservation Actions [top]

Conservation Actions:

There are no conservation actions in place for this endemic species. An action plan on the sustainable management of water use in the region is urgently needed and existing water legislation should be enforced. Fertilizers, pesticides and herbicides use for agriculture purposes need to be drastically reduced. Regional cooperation between Albania, FYROM and Greece would be an asset for coordinated conservation action for the Prespa Lake. Habitat monitoring should be introduced to determine the impacts of sedimentation and declining water quality for this species. The impact of the introduced fish are unknown, but the pea-clams are known to be fish-food in other lake habitats, and so more understanding of the impacts of the native and introduced species are recommended.

Citation: Albrecht, C., Hauffe, T. & Schreiber, K. 2010. Pisidium maasseni. The IUCN Red List of Threatened Species 2010: e.T155655A4815815. . Downloaded on 23 July 2018.
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