SURVEY OF OSTRACODES IN LAKES AND STREAMS IN A RECLAIMED SURFACE MINE, THE WILDS, SOUTHEASTERN OHIO

Ostracodes are known to be good indicators of environmental conditions. Surface water chemistry at The Wilds varies from north to south and appears to be a reflection of the reclamation process. Reclamation of surface mining at The Wilds occurred from 1974 to 1984 and encompassed several changes in reclamation laws. During reclamation approximately 40 lakes were constructed. Today surface water, exclusive of springs, can be divided into three geographic regions based on characteristic levels of total dissolved solids (TDS). The northern region typically has TDS values between 1200 to 1400 mg/L. TDS values in the middle region range between 800 to 1100 mg/L and in the southern region range between 100 to 500 mg/L. The pH values of surface water at The Wilds vary between 6.5 and 9.0 and appear to be primarily controlled by the limestone-rich spoil. Northern region lakes are fed by surface runoff/groundwater or a combination of surface runoff/groundwater and springs, have very small drainage basins and are flow-through lakes. Lakes in the middle region are fed by a combination of surface runoff/groundwater and springs, have large drainage basins and are flow-through lakes. Most of the southern region lakes are feed by surface runoff only, have small drainage basins and are not flow-through lakes. Southern region lakes based on TDS values appear to be above the groundwater table.

Ostracodes species were collected from sediment samples of several lakes from each of the above areas and from the three streams that drain the watershed. Spatial distribution of ostracode assemblages at The Wilds is demonstrative of the above trend in surface water chemistry. The identified assemblages Physocypria globula, Darwinula stevensoni, and Candona elliptica exhibit solute space preferences (measured by carbonate alkalinity/Ca ratio vs. TDS in ppm) as defined by NANODe. Carbonate alkalinity/Ca ratios vary from 0.83 to 4.77 due to the contrasting hydrochemistry across the sequentially reclaimed surface mine. From this data, the presence of Darwinula stevensoni appears to be an indicator of TDS values exceeding 1000 ppm characteristic of the central and northern subwatersheds.