OSTRACODES AS INDICATORS OF HYDROCHEMISTRY AT A RECLAIMED SURFACE MINE, THE WILDS, SOUTHEASTERN OHIO

Ostracode species distribution at The Wilds reflects the chronology of the reclamation that took place there between 1974 and 1984. The reclamation proceeded from north to south, and surface water parameters are indicative. 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 central 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. High TDS values of the lakes of the northern and central regions of The Wilds can be attributed to the fact that they are fed by a combination of groundwater, springs, and surface runoff. Most of the southern region lakes, however, are fed exclusively by surface water runoff, have small drainage basins and are not flow-through lakes. Southern region lakes based on TDS values appear to be above the groundwater table.

Since 2005, an ongoing survey of the ostracode species in certain lakes and streams at The Wilds has indicated a trend with respect to solute composition. A near linear trend that has emerged is Mg2+ concentration vs. Carbonate alkalinity/Ca ratio. The only outlier is from the northernmost of the sampled lakes. The only ostracode found there was Physocypria globula, which is known to have the highest amplitude of solute composition tolerance out of the three assemblages found at The Wilds (Physocypria globula, Darwinula stevensoni, and Candona elliptica). Further investigation will determine whether the tolerance amplitude is the reason for the breakdown of this trend.