MARINE SEDIMENT COPPER TOXICITY TO PHYTOPLANKTON COMMUNITIES IN CASTLE HARBOUR, BERMUDA

Abstract

Copper (Cu) is necessary for the survival of marine microorganisms such as phytoplankton, but it is toxic at high concentrations. When anthropogenic (originating from human activity) copper enters the marine environment it can accumulate in marine sediments on the ocean floor. Because of this, ecosystems near boatyards and treatment plants tend to have highly copper contaminated sediments. Castle Harbour, Bermuda is the location of an Airport Waste Management Facility (the Airport Dump), where copper in solid metal waste can easily leach into the Castle Harbour ecosystem. Very few studies have been conducted to determine the total amount of copper in contaminated marine sediments in Castle Harbour, with only one study being published since 1990. In this thesis, marine sediment was collected from various sites in Castle Harbour, as well as from St. George’s Boatyard. The total amount of copper in the sediments was determined, and the sediments were then exposed to natural incubations of phytoplankton communities from Castle Harbour. Results showed that there is a slight increase of sediment copper contamination toward the Airport Dump within Castle Harbour. However, when compared to sediment collected from St. George’s Boatyard, sediment copper contamination in Castle Harbour is significantly lower. Phytoplankton communities exposed to copper contaminated sediments from St. George’s Boatyard showed significant declines in biomass and growth, while little to no decline was observed in the phytoplankton communities exposed to sediment collected from Castle Harbour.