Marshall McLuhan's Global Village has become a biological reality as exotic marine life is now known to have entered Canada in Great Lakes shipping ballast waters. As human activity increases worldwide, the potential movement of exotic or pathogenic (disease causing) organisms of all types also increases. The damage resulting from this activity, from ecosystem, human health and economic points of view, is presently not well understood. However, recent introductions of the zebra mussel (Dreissena polymorpha), believed to have arrived in the ballast water of a Russian vessel, the spiny water flea (Bythotrephes cederstroemi), and the River Ruffe, (Gymnocephalus cernuus) a fish, to North American waters are examples of these non-native intruders, which are wreaking havoc on our waterways.

Diver going down to inspect accumulations of zebra mussels which block water intakes at treatment plants and power stations.

Zebra mussels, with no natural predators to limit their growth, have caused millions of dollars worth of damage by clogging up the water intakes of water treatment plants and power stations. While drastically reducing mature fish populations, zebra mussels ironically improve the clarity of the lakes they infest.

The Canadian Coast Guard has in place, guidelines for voluntary open ocean ballast water exchange by ocean-going vessels travelling upstream into the fresh water of the St. Lawrence Seaway and the Great Lakes System. In addition, the US Coast Guard has regulated that ballast water salinity of vessels of concern be at least 30 parts per thousand (ppt) in order to control freshwater species with a lower limit of less than 25 ppt.

The intent of these actions is to ensure that exotic freshwater organisms, which may travel from foreign ports in ballast water, are either flushed out of ballast tanks or are exposed to salinities which would cause mortality prior to entering North American freshwaters.

While it has been reported that most vessels comply with in-place guidelines, the evidence suggests that some do not. Further, even those vessels that do exchange ballast, may harbour viable organisms in areas of salinity stratification within ballast tanks or in accumulated wet sediments and unpumpable ballast of vessels that report "no ballast on board".

Following a preliminary investigation completed by Aquatic Sciences Inc. for the Canadian Coast Guard in 1994/95, it was apparent that development of improved sampling equipment was necessary prior to initiation of any large scale ballast water study.

This preliminary project led to development of more effective sampling equipment and protocols. These could be used to better determine both compliance rates of upbound shipping as well as the effectiveness of the present guidelines for prevention of introductions of exotic species to the Great Lakes and associated waterways.

During 1994 field sampling, thirteen downbound vessels were boarded in the Welland Canal in order to test and refine sampling equipment and protocols.

In all cases where vessels were carrying reportable ballast water, samples were successfully retrieved. More importantly, in at least four vessels which reported no ballast on board, sufficient water was collected through sounding pipes to measure salinity and in some cases living invertebrates (organisms) were also detected. It is generally accepted that ballast waters with high saline levels are much less likely to introduce unwanted species into our waterways.

This article has been abridged.