Troy Pond, a small coastal embayment located along the south-western coast of Cape Breton, has developed into a system characterized by strong odours of hydrogen sulfide that appears to the result of anaerobic decomposition of seaweed wrack that has accumulated within its innermost subtidal zone. In order to confirm that this is due to the anaerobic decomposition of seaweed wrack, and to better understand the conditions that exist in the pond, a study was carried out to monitor the temporal variations in dissolved oxygen level and a number of other water quality parameters within the pond. In addition, a survey was carried out to determine if other coastal ponds exhibiting similar characteristics are present along the south-western coastline of Cape Breton. The results of the study indicate that Troy Pond does become anoxic for long periods of time, particularly within its innermost subtidal area which contains large masses of
partially decomposed seaweeds. The outer portion of the pond, which is shallower, also undergoes periods of anoxic conditions, but to a much lesser extent than does the inner pond. An analysis of the variation in dissolved oxygen concentration indicated that it is controlled largely by the extent of tidal flushing of the pond, which in turn is a function of tidal amplitude and the velocity and direction of winds.
An aerial and ground survey indicted that the situation that exists within Troy Pond is not widespread. Although there was some evidence of seaweed wrack accumulation and very localized development of odours associated with hydrogen sulphide at two sites located very close to Troy Pond, there was no indication of the presence of other sites along the coastline having the severity of characteristics present at Troy Pond.