California floater (Anodonta californiensis)

Photo not available for this species
Category: Molluscs
State status: Candidate
Vulnerability to climate change (More details)


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Climate vulnerability

Sensitivity to climate change


There is limited information regarding the sensitivity of California floaters to climate change. This species, which has already experienced significant declines over the past few decades, is generally found in shallow pools of freshwater streams and reservoirs with good water quality and a sufficient abundance of small fish who serve as hosts for mussels during their transition from the larval to juvenile stage. Therefore, their main sensitivity is likely to stem from climate-induced changes in water quality and host fish abundance. For instance, increased intensity of winter storms could lead to higher flow in rivers and increased nutrient runoff, both of which would degrade and reduce available mussel habitat. Additionally, increases in water temperature could lead to altered abundance of host fish for larval stage mussels, thus leading to declines in abundance. This species may also be sensitive to summer droughts, which could lead to shallower water levels in the pools that serve as mussel habitat, and potential air exposure and mortality, particularly since mussels have limited mobility and thus limited ability to respond to changes in habitat.
Confidence: Low

Exposure to climate change


  • Increased water temperatures
  • Altered flow regimes
  • Drought
Confidence: Low


This species is identified as a Species of Greatest Conservation Need (SGCN) under the State Wildlife Action Plan (SWAP). SGCN-classified species include both those with and without legal protection status under the Federal or State Endangered Species programs, as well as game species with low populations. The WDFW SWAP is part of a nationwide effort by all 50 states and five U.S. territories to develop conservation action plans for fish, wildlife and their natural habitats—identifying opportunities for species' recovery before they are imperiled and more limited.
This species is identified as a Priority Species under WDFW's Priority Habitat and Species Program. Priority species require protective measures for their survival due to their population status, sensitivity to habitat alteration, and/or recreational, commercial, or tribal importance. The PHS program is the agency's main means of sharing fish and wildlife information with local governments, landowners, and others who use it to protect priority habitats for land use planning.