**7. Conclusions**

The loss of biodiversity across biomes and habitats has direct and profound implications for human populations around the world (Sala et al., 2000). The functioning of both terrestrial and aquatic ecosystems is dependent on the diversity of their constituent organisms (Covich et al., 2004; Kinzig et al., 2002; Loreau et al., 2001), and the dependence of humans on these ecosystem services makes protecting and restoring biodiversity a priority for both the present and future generations. Freshwater ecosystems have received less consideration from the public and researchers, despite the critical linkages between freshwater systems and human well-being (Aylward et al., 2005; Costanza et al., 1997; Jackson et al., 2001). It is clear that through our actions we are degrading and damaging our freshwater ecosystems beyond their abilities to recover (Allan and Flecker, 1993; Dudgeon et al., 2006; Richter et al., 1997; Strayer and Dudgeon, 2010), and continuing these unsustainable activities puts all the world's inhabitants at risk.

Freshwater unionid mussels are an often-overlooked part of freshwater biodiversity, and one that is the most threatened (Ricciardi and Rasmussen, 1999; Williams et al., 1993). Unionids are key components to their ecosystems, carrying out many important ecological functions (McCall et al., 1995; Strayer et al., 1999; Vaughn and Hakencamp, 2001) and influencing the diversity of benthic communities (Aldridge et al., 2006; Gutierrez et al., 2003; Spooner and Vaughn, 2006). Their unique reproduction strategy, feeding behaviors, specific habitat requirements, and valuable shell and pearls have put them at risk to human-driven disturbances, and have contributed to their worldwide decline in both abundance and richness (Bogan, 1993; Vaughn, 1997). The drivers of the decline in unionid biodiversity are the same as those of freshwater diversity in general: pollution, habitat destruction, overharvest, altered flows, invasion by non-native species, and climate change, but because of their lifestyles and high degree of endemism, they are being especially hard hit (Strayer et al., 2004).

The solutions to the decline in unionid biodiversity are simple, but not easy. Reducing pollution (Caruso, 2000; Lowrance et al., 1997), restricting harvesting (Strayer et al., 2004), ensuring ecologically sustainable flows (Arthington et al., 2006; Layzer and Scott, 2006), habitat protection and restoration (Miller et al., 2010; Muotka et al., 2002; Wilson et al., 2011), combating non-native invaders (Strayer, 2008b), mitigating and planning for the effects of climate change (Heino et al., 2009; Poff et al., 2002), creating connected freshwater protected areas (Heino et al., 2009; Saunders et al., 2002) and artificially enhancing wild populations (Cope and Waller, 1995; Strayer et al., 2004) are all necessary to restore freshwater ecosystems and the mussels that occupy them.

It is clear that any successful freshwater conservation plans must be large in scale and longterm in scope, and take into consideration the multiple chronic stressors that are causing the alarming decline in freshwater pearly mussels. It is equally clear that failure to take concrete steps to halt and reverse the trend of biodiversity loss in unionid mussels could result in the permanent loss of this unique and important group of animals.
