Minor improvement for intertidal seaweeds and invertebrates after acid mine drainage diversion at Britannia Beach, Pacific Canada

In December 2001, acid mine drainage (AMD) from an abandoned copper mine at Britannia Beach (British Columbia, Canada) was diverted to flow from Britannia Creek into an outfall at 30 m depth in Howe Sound. Britannia Beach was studied in early 2003 to determine whether AMD diversion resulted in improved conditions for intertidal organisms. Species number and abundance have increased at the intertidal zone since AMD diversion, although they were still lower than at an unpolluted control site nearby (Furry Creek). Survivorship and growth rates of transplanted Mytilus trossulus (mussel) have increased since AMD diversion, although they were still significantly lower than at the control site. Transplanted Fucus gardneri (seaweed) performed better than before the AMD diversion; at Britannia Beach the chlorophyll a concentration in tissues was not significantly different from that at the control site, although the concentration of chlorophyll c in tissues and the chlorophyll c to a ratio was lower than at the control site six weeks after transplantation. Britannia Beach is still subject to leaching of metals from surrounding soils, low levels of AMD coming down the creek, and AMD discharge from the deep outfall. Although there has been an improvement, the intertidal environment at Britannia Beach still seems unable to support normal growth and survival of organisms.