Aspects Of Global Distribution Of Six Marine Bivalve Mollusc Families
We compared the global distribution of six families of bivalves based on their economic importance in terms of fisheries and aquaculture production: Veneridae (venus shells), Mactridae (surf clams), Donacidae (wedge shells), Myidae (softshell clams), Pharidae, and Solenidae (razor clams). All distribution data were gathered from the openaccess databases GBIF (Global Biodiversity Information Facility) and OBIS (Ocean Biogeographic Information System). Species nomenclature and synonyms were reconciled using WoRMS (World Register of Marine Species). Geographic coordinates related to species records noted as fossils, that lacked a geogographic precision, and where precision was >100 km were excluded from the analysis. Comparison with WoRMS indicated that about half of the known species and 64% of genera had data in GBIF and OBIS combined. All distribution records were from shallow coastal areas, and a sampling bias in Europe was evident. There were no records of any of the families in Antarctica, and only the Mactridae and Veneridae occurred in New Zealand. The GBIF and OBIS data tended to indicate wider distribution ranges than found in a survey of the literature. However, in several cases this reflected species introduced outside their native range. A significant amount of species distribution data was easily accessible from GBIF and OBIS for about half the described species of these bivalve families. However, the metadata that describes the datasets in GBIF and OBIS merited improvement, and considerable cleaning of the data was necessary before use. Studies on biogeography need to consider the effect of species introductions outside their native range on their analyses. Despite these limitations, the analysis found distinct biogeographic patterns at a family level that merit further research into the evolutionary origins and dispersal patterns of the six families.