USGS Home Contact USGS Search USGS

Ohio Water Science Center

Ohio Aquatic Gap Analysis—An Assessment of the Biodiversity and Conservation Status of Native Aquatic Animal Species

U.S. Geological Survey, Open-File Report 2006–1385

By S. Alex. Covert, Stephanie P. Kula, and Laura A. Simonson

National Gap Analysis Program

    The goal of the GAP Analysis Program is to keep common species common by identifying those species and habitats that are not yet adequately represented in the existing matrix of conservation lands. The Gap Analysis Program (GAP) is sponsored by the Biological Resources Discipline of the U.S. Geological Survey (USGS). The Ohio Aquatic GAP (OH-GAP) is a pilot project that is applying the GAP concept to aquatic—specifically, riverine—data. The mission of GAP is to provide regional assessments of the conservation status of native animal species and to facilitate the application of this information to land-management activities. OH-GAP accomplished this through

• mapping aquatic habitat types,
• mapping the predicted distributions of fish, crayfish, and bivalves,
• documenting the presence of aquatic species in areas managed for conservation,
• providing GAP results to the public, planners, managers, policy makers, and researchers, and
• building cooperation with multiple organizations to apply GAP results to state and regional management activities.

    Gap analysis is a coarse-scale assessment of aquatic biodiversity and conservation; the goal is to identify gaps in the conservation of native aquatic species. It is not a substitute for biological field studies and monitoring programs. Gap analysis was conducted for the continuously flowing streams in Ohio. Lakes, reservoirs, wetlands, and the Lake Erie islands were not included in this analysis. The streams in Ohio are in the Lake Erie and Ohio River watersheds and pass through six of the level III ecoregions defined by Omernik: the Eastern Corn Belt Plains, Southern Michigan/Northern Indiana Drift Plains, Huron/Erie Lake Plain, Erie Drift Plains, Interior Plateau, and the Western Allegheny Plateau.

    To characterize the aquatic habitats available to Ohio fish, crayfish, and bivalves, a classification system needed to be developed and mapped. The process of classification includes delineation of areas of relative homogeneity and labeling these areas using categories defined by the classification system. The variables were linked to the 1:100,000-scale streams of the National Hydrography Dataset of the USGS. Through discussions with Ohio aquatic experts, OH-GAP identified eight separate enduring physical features which, when combined, form the physical habitat type:

• Shreve link (a measure of stream size)
• Downstream Shreve link (a measure of stream connectivity and size)
• Sinuosity
• Gradient
• Bedrock
• Stream temperature
• Character of glacial drift
• Glacial-drift thickness

    Potential distribution models were developed for 130 fish, 70 bivalve, and 17 native crayfish species. These models are based on 5,686 fish, 4,469 crayfish, and 2,899 freshwater bivalve (mussels and clams) sampling locations, the variables describing the physical habitat types, and variables indicating the major drainage basins and Omernik’s Level III ecoregion. All potential species distributions are displayed and analyzed at the 14-digit hydrologic unit (14-HUs), or subwatershed, level. Mainland Ohio contains 1,749 14-HUs. All statistics and conclusions, as well as spatial data, are discussed and presented in terms of these units.

    The Ohio Aquatic Gap Analysis Project compiled a map of public and private conservation lands and OH-GAP classified the lands into four status categories (status 1 through status 4) by the degree of protection offered based on management practices. A status of 1 denotes the highest, most permanent level of maintenance, and status 4 represents the lowest level of biodiversity management, or unknown status. The results of this mapping show that only about 3.7 percent of the state’s land (4.3 percent if lakes and reservoirs are also included) is protected for conservation, either publicly or privately. Of this total, state agencies control about 52 percent, and Federal agencies control about 29 percent.

    Conservation areas that presently protect a portion of Ohio’s aquatic biodiversity were identified through the analysis of the distributions of species and conservation lands on a 14-HU scale. In addition, based on measures of predicted species richness and taxa richness, 75 (out of 504) 14-HUs in the Lake Erie Basin and 67 (out of 1,291) 14-HUs in the Ohio River Basin were identified for their conservation potential. Results show that 22 fish species and 2 bivalve species had predicted distributions exclusive of conservation lands classified as status 1 or status 2. Nine of these fish species are considered rare, threatened, or endangered in the state. Status 1 and status 2 lands are generally considered by GAP to offer adequate protection.

   The primary factor used by OH-GAP for identifying potential high-priority conservation areas was species richness. Because of the known gradient of species diversity, the Lake Erie and Ohio River Basins were analyzed separately for all taxa. Fifteen percent (75 of 504) of the 14-HUs in the Lake Erie Basin were identified by OH-GAP as high potential priorities for conservation. Thirty-seven of them already have some conservation lands located within them. In the Ohio River Basin, 57 of 1,291 14-HUs (4.5 percent) were identified by OH-GAP as potential high-priority conservation areas for conservation using species richness. Of the 57 14-HUs identified as potential high-priority conservation areas, 56 percent already have conservation lands. In both the Lake Erie and Ohio River Basins, a larger, though not significant, percentage of 14-HUs with existing conservation land were identified by OH-GAP for their potential for high species richness. It is beyond the scope of this report to assess whether high-quality habitats were deliberately protected or whether conservation of habitat has allowed species to thrive. Because only enduring physical characteristics were used in the models, it is likely that these habitats were deliberately protected, and this gap analysis provides further evidence of the habitat quality.

Data Use and Availability
    The primary products of the Ohio Aquatic GAP project are geospatial data for land stewardship, stream-habitat types, and predicted distribution models for native fish, crayfish, and bivalves. Associated OH-GAP geospatial data include mapped locations of fish, crayfish, and bivalves. These data are available from the USGS along with this report.

This document is available in Portable Document Format (PDF)

To view and print report you will need to use Adobe Acrobat Reader (available as freeware, best if viewed using Version 8.0.0+)

Users with visual disabilities can visit Online conversion tools for Adobe PDF documents web page

Executive Summary (48.3 KB) - 4 pages

Main Body [includes Executive Summary] (4.04 MB) - 137 pages

Appendix A - Ohio Stream Classification Codes (69 KB) - 3 pages

Appendix B - Maps of Ecological Drainage Unit (EDU), Major Watersheds, and Level III Ecoregions (202 KB) - 3 pages

Appendix C - Stream physical habitat types (3.98 MB) - 120 pages

Appendix D - Bivalve specimen collectors for the data obtained from the Ohio State University Museum of Biological Diversity (256 KB) - 22 pages

Appendix E - A dichotomous key for categorization of land units, based on biodiversity management, for land-stewardship map (33.1 KB) - 1 page

Appendix F - The dichotomous key for categorization of land units, based on biodiversity management, for land-stewardship map, in flowchart format (30.3 KB) - 1 page

Appendix G - Ohio land stewardship areas in GAP conservation status category 1 and 2 (209 KB) - 11 pages

Appendix H - Stakeholders and consulted experts (28.2 KB) - 1 page

Appendix I - Data and report reviewers (31.4 KB) - 2 pages

Maps of Predicted Fish Distributions (20.5 MB) - 130 pages

Maps of Predicted Crayfish Distributions (2.67 MB) - 17 pages

Maps of Predicted Freshwater Bivalve Distributions (10.8 MB) - 70 pages

Fish Species List 32.6 KB) - 2 pages

Crayfish Species List (18.5 KB) - 1 page

Freshwater Bivalve Species List (26.7 KB) - 2 pages

Suggested Citation:

Covert, S.A., Kula, S.P., and Simonson, L.A., 2007, Ohio Aquatic Gap Analysis: An Assessment of the Biodiversity and Conservation Status of Native Aquatic Animal Species: U.S. Geological Survey Open-File Report 2006–1385, 509 p.

AccessibilityFOIAPrivacyPolicies and Notices
U.S. Department of the Interior, U.S. Geological Survey Persistent URL: http://pubs.water.usgs.gov/ofr20061385 Page Contact Information: USGS Publishing Network Last modified: Saturday, 12-Jan-2013 22:26:50 EST

---