Summary
During the 2009/2010 summer field season a comprehensive environmental impact assessment (EIA) of the sewage discharge at Davis Station, East Antarctica was conducted. As part of this EIA, a preliminary histopathological survey of the gills and liver in the emerald rock cod (Trematomus bernacchii) was completed to describe the nature and extent of impact from the sewage plume on local fish populations. Twenty fish were collected from four sites on a spatial gradient extending out from the point of discharge. A histological health index was developed based on structural alterations evident in fish tissues. All fish sampled from within 500 m of the outfall exhibited significant histological alteration in all major tissues. Fish from other sites also showed some alteration in either gill and /or liver tissue, the degree of which decreased with increasing distance from the outfall. Given the pathologies observed in this initial pilot study and the low sample size available for analysis, this data set was extended in the summer of 2012/2013 in which a further 164 fish were collected from 6 sites. This research will use a weight of evidence approach, alongside ecological monitoring, chemical analysis, ecotoxicological testing and dispersal modelling of the discharge plume to determine the environmental impact of the sewage discharge.