Species richness, distribution and relative abundance of freshwater mussels (Unionidae) of the Strawberry River, Arkansas.

摘要

The purpose of this study is to document the species richness, distribution and abundance of fresh water mussels, address whether there are distinct communities in the Strawberry River and assess if any environmental variables are associated with mussel distributions. The Strawberry River watershed (1500 km 2) is located within the North-central Arkansas. Freshwater mussels were surveyed from the headwater to mouth during 1990--2000s. Environmental variables of landcover, geology, soiltype, soil texture, northness, eastness, topographic moisture index (TMI), slope and drainage area were analyzed at the local and subwatershed scale. The mussel presence/absence data of 38 fresh water mussels in 57 different sites and the different environmental variables were analyzed using Principle Components Analysis.;Of the 38 species of mussels collected at 57 sites, 3 species were most abundant overall: Amblema plicata (Say 1817) at 17%, Actinonaias ligamentina (Lamarck 1819) at 10%, and Elliptio dilatata (Rafinesque 1820) at 9.6%. There were four distinct communities of freshwater mussels; Lampsilis cardium (Rafinesque 1820), Amblema plicata (Say 1817), Tritogonia verrucosa (Rafinesque 1820) and Potamilius purpuratus (Lamarck 1819). Considering the abundance and the availability, the following species were categorized as rare species in the Strawberry River; Ellipsaria lineolata (Rafinesque 1820), Epioblasma triquetra (Rafinesque 1820), Obovaria jacksoniana (Frierson 1912), Pyganodon grandis (Say 1829) & Utterbackia imbecillis (Say 1829). The Strawberry River mussel assemblage has a relatively high species richness and has a high percentage (∼61%; n=23 species) of species of conservation concern (state heritage rankings S1-S3). These distribution patterns also showed significant correlation with sub-watershed level (n=45, 50%) and local level (n=16, 18%) environmental variables. Thus, conservation strategy should focus on protecting existing mussel populations and habitat as well as the management strategies should focus on the larger scales (subwatershed) rather than local microscales of the watershed.