Use of preserved museum fish to evaluate mercury contamination in two Oklahoma rivers

To determine if preserved museum fish specimens could be used to evaluate mercury contamination through time, we preserved largemouth bass (Micropterus salmoides) in formalin-ethanol and formalin-isopropanol and found no significant change in mercury concentration over 160 days. To evaluate how mercury contamination of two rivers in southeastern Oklahoma may have changed through time, we determined mercury concentrations in preserved longear sunfish (Lepomis megalotis) from the Sam Noble Oklahoma Museum of Natural History. Longear sunfish had been collected over 41- and 79-year periods from Glover and Mountain Fork Rivers, respectively. Glover River is unimpounded, whereas Mountain Fork River was impounded upstream from the sampling sites in 1968. Mercury concentrations in longear sunfish from Glover River showed no temporal trend from 1963 to 2004. Mercury concentrations in longear sunfish from Mountain Fork River showed no temporal trend from 1925 to 1993 but then declined from 1993 to 2003.