Ozark Plateau - Hypoxia and Freshwater Mussels


Low dissolved oxygen (hypoxia) is an important factor limiting the distribution and abundance of aquatic animals. Hypoxia results from nutrification and organic enrichment of water and sediments, which lead to increased biological oxygen demand and depletion of dissolved oxygen (DO). The impacts and significance of hypoxia are well-recognized and have led to the establishment of criteria for nutrient loading and DO by the U.S.EPA and other agencies. However, national criteria for DO are based primarily upon the responses of fish and do not necessarily address the needs of other organisms such as benthic invertebrates. Among these are many species of native freshwater mussels.

Native mussels include a large proportion of the animal species that are recently extinct or currently threatened and endangered in North America and worldwide. Although there is widespread concern about the effects of environmental hypoxia on mussels and other aquatic invertebrates, relatively little information is available compared to better studied groups such as fish. This study, funded by U.S.EPA, focuses on the effects of DO and temperature on rate of oxygen consumption, survival, and growth of juvenile mussels, and also examines effects on larval mussels, which are brooded within the female mussel for many months. These data will help to inform regulations and recommendations concerning dissolved oxygen in freshwater systems.


For more information on native mussels, visit the Unio Gallery at http://unionid.missouristate.edu/.