Science

The Refuge Vision Statement reads: "The Ohio River Islands National Wildlife Refuge will create a linked network of over 12,000 acres of floodplain forests, wetlands, and aquatic habitat stretching over 400 miles from Pittsburgh to Cincinnati. These refuge lands and waters will fulfill the needs of fish, wildlife and plants that are native to "big river" ecosystems. Through reforestation, exotic species control, and wetland restoration, the Refuge will serve as an anchor for biodiversity and a model for habitat restoration throughout the Ohio River Valley ecosystem. We will forge habitat and management links with other units of the National Wildlife Refuge System."


The Service manages fish and wildlife habitats considering the needs of all resources in decision-making. A requirement of the Refuge Improvement Act is to maintain the ecological health, diversity, and integrity of refuges. The refuge is a vital link in the overall function of the ecosystem. To offset the historic and continuing loss of riparian and forested floodplain habitats within the ecosystem, the refuge helps to provide a biological "safety net" for migratory non-game birds and waterfowl, threatened and endangered species, and other species of concern.

The following scientific areas of interest are not inclusive; they are but a sampling on the refuge's current efforts (for more detailed information about refuge resources, follow the links in the menu bar at upper left).

Erosion of Islands

Erosion of islands and banks, and sedimentation and siltation of shallow water embayment areas (specifically) and the river (in general) adversely affect water quality and the general bottom habitat conditions for mussels and other benthic invertebrates and fish populations. Sand and gravel dredging also physically impact island stability, and could damage all culturally important islands.

Invasive Species

The introduction and spread of invasive plants and aquatic species on Refuge lands and in the Ohio River threaten native riparian vegetation and freshwater mussel species. Among the most recognized of these nuisance exotics are the plants "Japanese knotweed" and "mile-a-minute" as well as the zebra mussel. Invasive species cost our Nation's economy an estimated $123 billion annually and are second only to habitat destruction in threatening extinction of native species. 

Mussel Recovery

Mollusks on the Refuge include freshwater mussels (the most diverse group), aquatic snails, and terrestrial snails. There are currently 50 species of freshwater mussels remaining in the Ohio River today, and 38 of these have been collected on the Refuge so far (Appendix D). Historically, there were upwards of 80 species in the free-flowing Ohio River, but habitat changes over the past 100 years have resulted in the extinction of at least 3 species, and the extirpation of many more. In addition to the habitat and water quality problems which mussels have faced, add the new threat caused by the invasion of the exotic zebra mussel. Zebra mussels first entered the Refuge in 1993, and since that time, their density has exploded to 13,000 animals per square meter. Zebra mussels compete with native mussels for food and oxygen, interfere with their reproduction, and encrust native mussels so heavily that the native mussels cannot open and close their shell, burrow, or move effectively. It's easy to see why freshwater mussels are the most imperiled group of animals on the Refuge.

Every Refuge island has been surveyed at least once, and each one has some mussel fauna associated with the underwater habitat surrounding it. At least two federally endangered mussels occur on the Refuge (pink mucket and fanshell) in the Belleville, Racine, RC Byrd, and Greenup pools. The most diverse mussel bed is found at Muskingum Island, with 28 species and an average density of 12 live mussels per square meter. Mussels generally require clean-swept sand, gravel, cobble and boulder habitat, and well oxygenated and nutrient rich waters. These habitats are abundant around the islands.

Commercial harvest of mussels (primarily for the cultured pearl industry) is generally permitted in Kentucky waters, but not in the states of Pennsylvania, Ohio or West Virginia. However, there are sanctuaries in place adjacent to the Kentucky Refuge islands which prohibit commercial harvest from those areas.