A novel approach for the development of tiered use biological criteria for rivers and streams in an ecologically diverse landscape.

Water resource protection goals for aquatic life are often general and can result in under protection of some high quality water bodies and unattainable expectations for other water bodies. More refined aquatic life goals known as tiered aquatic life uses (TALUs) provide a framework to designate uses by setting protective goals for high quality water bodies and establishing attainable goals for water bodies altered by legally authorized legacy activities (e.g.

A paleozoological perspective on unionid (Mollusca: Unionidae) zoogeography in the upper Trinity River basin, Texas.

In north central Texas, USA, the zoogeography of unionids in the Trinity River is thought to consist of upland and lowland biogeographic components reflective of differences in upstream and downstream hydraulic conditions. Historical and modern surveys from a limited number of localities were used to delineate these zoogeographic provinces based on the absence of several species thought to occur only in the lower Trinity River drainage. Available zooarchaeological data indicate that at least one species considered absent from the upper Trinity River basin was present during the late Holocene (roughly the last 2500 years), suggesting that both biogeographical provinces shared similar mussel fauna in the recent geological past.