Atlas of Freshwater Bivalves 2007

Study Extent

The geographic area considered for the study was Mainland Portugal. Since there is some cross-border data, some registers were made in Spain.

Sampling

The data was obtained for the elaboration of the Atlas, with the survey of the species distribution at Mainland Portugal. At each location the survey of the freshwater bivalves were performed using specific techniques for detecting their presence or absence. Whenever possible, the abundance of each species was assessed. Data collection of the occurrence was also based on previous publications. All data was inserted in a specific database build for the project.

Quality Control

All initial data was inserted in a specific relational database built specifically for the project, which implemented several quality control methods. In the preparation of the dataset for GBIF publication, data consistency was verified using cluster algorithms using OpenRefine.

Method steps

1. The dataset presents information of the occurrence status (presence or absence) of the species in each location. There are also classes of abundance for these species, as following: absent = value 0; rare = value 1; common = value 2; abundant = value 3; very abundant = value 4. In some cases, the presence of a species was recorded in a locality, however was not possible to assess its abundance. Aggregation of original data from several sources (see above) into a purpose specific relational database built for the project. For details, see Reis (2006). The preparation of the dataset for GBIF publication used as source the geographic layer in shapefile format. The data layer was a vector layer containing points. The following steps were performed: - Conversion of the spatial layer to geographic coordinates using WGS84 as reference system; - Used the points to determine the locations based on the Carta Administrativa Oficial de Portugal 2020 (CAOP2020) and OpenStreetMaps; - Exported to csv, unpivot the data in the table and reinterpreted attributes matching to DwC standard terms.

The Atlas of Bivalves recorded data of 13 freshwater species of Bivalvia in 03 orders and 04 families. All the bivalves were identified up to the species level.

1. Animalia
   rank: kingdom
2. Mollusca
   rank: phylum
3. Bivalvia
   rank: class
4. Unionida
   rank: order
5. Venerida
   rank: order
6. Sphaeriida
   rank: order
7. Unionidae
   rank: family
8. Cyrenidae
   rank: family
9. Margaritiferidae
   rank: family
10. Sphaeriidae
    rank: family
11. Anodonta anatina
    common name: Duck mussel rank: species
12. Anodonta cygnea
    common name: Swan mussel rank: species
13. Potomida littoralis
    rank: species
14. Unio delphinus
    rank: species
15. Unio tumidiformis
    rank: species
16. Margaritifera margaritifera
    common name: Freshwater pearl mussel rank: species
17. Pisidium casertanum
    common name: Ubiquitous peaclam rank: species
18. Pisidium milium
    common name: Quadrangular pillclam rank: species
19. Pisidium nitidum
    common name: Shining pea mussel rank: species
20. Pisidium personatum
    common name: Red-crusted pea mussel rank: species
21. Pisidium subtruncatum
    common name: Short-end Peaclam rank: species
22. Musculium lacustre
    common name: Lake Orb-Mussel rank: species
23. Corbicula fluminea
    common name: Asian clam rank: species

Mainland Portugal. There is also some cross-border data, with records in Spain.