Spatial Variability of Reproductive and Size Characteristics of the Northern Mummichog (Fundulus heteroclitus macrolepidotus) Collected Near Municipal Wastewater Discharges

Abstract Northern mummichog (Fundulus heteroclitus macrolepidotus) have been widely considered to be suitable for environmental effects monitoring despite concerns of spatial variability observed in energy reserves and reproductive indices. In this study, temporal and spatial variability in gonadosomatic index (GSI), liversomatic index (LSI), and condition factor (K) were examined across two sites in 2006 and 10 sites (four sites exposed to wastewater discharge; six reference sites) in 2007. In 2006 GSI, LSI, and K appeared highly variable and significantly different for both males and females. In 2007, female K and gonad weight were significantly different among all sites. For males, significant differences in K and liver weight were observed among sites. Extensive spatial variation in GSI, LSI, and K observed between reference sites suggests current standardized Canadian Environmental Effects Monitoring (EEM) methods, including effect size and duration of sampling, should not be adopted for use with the northern mummichog F. h. macrolepidotus.