Last year's massive bird and fish die-off in Severn Sound waters along the coast of Tiny Tow nship alarmed residents and sparked questions about human and animal safety and the integrity of our water supply. The cause of the die-off was eventually tied to botulism bacteria, which formed a deadly paralytic toxin after it was ingested by two of the most notorious invasive species in our waterways--Zebra Mussels and Round Gobi, a small fish.

Bob Bowles, a well-known naturalist addressing the recent SSEA workshop on invasive species, said, "The presence of zebra mussels promoted the growth of filamentous algae, which is attached to the bottom of the lakebed."

The zebra mussels ingested the botulism bacteria present among the algae, the Round Gobi ingested the zebra mussels and the toxin made its way up the food chain, paralyzing diving ducks and larger fish that feasted on Round Gobi.

Another local fish die-off several years ago was connected to the Koi herpesvirus, and the suspected cause was flushing infected koi or goldfish down toilets.

Common carp are very susceptible to the disease, first found in North America in 1999, and it killed thousands of fish; ironically, native to Europe and Asia, many carp species are also considered to be invasive.

The link between these die-offs is the presence of an invasive species or disease resident fish have no defense against.

Everything that enters our water supply has the potential to cause lasting harm and the SSEA tries to limit the damage through ongoing community education and outreach.

One recent event the SSEA hosted was naturalist Bob Bowles' presentation to municipal partners on invasive species called Aliens Among Us.

In the presentation Bowles stated an invasive species is "any species that has been introduced to an environment where it is not native and has since become a nuisance through rapid spread and increase in numbers, often to the detriment of native species."

Because invaders initially have no natural predators and they're not affected by local diseases, they can quickly proliferate and impact the balance of our ecosystems--and it's not just animal invaders that cause harm.

Bowles says Glossy Buck-thorn, a shrub native to Europe, Western Asia and Northern Africa, is the worst invader in our area; it grows pretty much anywhere and birds find its berries delicious and spread the seeds in a wide area through defecation.

When the seeds grow into dense thickets they create shade and kill all native forest and wetland growth, creating a monoculture.

Bowles says, "Glossy Buckthorn has the biggest impact in our area. I've done inventory for the Wye Marsh and Severn Sound Environmental Association and found wet areas completely dominated by it. It's just a little green shrub but it's completely dominating regeneration so that in 30 or 40 years, we're not getting new maple or beech trees or other native growth, we're just getting Glossy Buckthorn." A changing landscaping courtesy of invasive species is not something the SSEA wants to happen and with continuing municipality and resident support, it can ensure it doesn't.

"Back in the early 1990s", said Keith Sherman, Executive Director of the SSEA, "a Remedial Action Plan (RAP) was developed in our area to address many specific environmental concerns: The first stage described the environmental conditions and problems; the second stage was to lay out a plan for remedial action that would lead toward taking Severn Sound off the list of Great Lakes Areas of Concern by protecting good habitat and restoration of habitat that had been degraded." While most of the projects had partial government funding, the municipalities and some landowners contributed their own funds into what was a true community effort to remedy environmental wrongs, but environmental concerns elsewhere in Ontario threatened to pull the plug on environmental stewardship before the RAP was completed.

Hamilton Harbour, the St. Lawrence River and other large areas needed many years of ongoing remedial action and local residents were concerned that Severn Sound might get forgotten before it was delisted as an Area of Concern. As a result, the Severn Sound Environmental Association was formed with partnerships between municipalities and the provincial and federal governments. Sherman says, "They all agreed to fund the operation of an office in the area, promoting the remedial action plan and finishing the work because at that time the plan was only in the second of three stages and we needed to complete it." Stage three of the RAP process was the review of completed projects called for in the stage two RAP but it also addressed how to manage ongoing projects, like storm water drainage and phosphorus load monitoring.

Phosphorus was a huge concern in Penetanguishene Bay, where large loads of the element poured into the bay for much of the twentieth century from older sewage treatment facilities, nearby farms and faulty septic systems. Phosphorus influences excessive growth of algae in the water and when researchers measured water clarity in the early 1990s using a Secchi disk (a circular disk lowered into the water to measure transparency from the surface), they could only see one metre down. Penetanguishene Bay was like pea soup.

Sherman says, "The water column clarity was poor due to heavy growths of algae. To control the algae growths you need to control the phosphorus. In the 1990s we had a minimum of 6,000 kg of phosphorus coming into the bay per year. A few years later, once the municipality got funding for the upgrade of their systems, the amount was reduced to just over 2,000 kg and that one metre Secchi disk turned into a four metre Secchi disk of very clear water." The new phosphorus load factored in population growth in the area with the upgrade of the Town's two sewage treatment plants. The results were very impressive and encouraging to the environmental stewards.

The Severn Sound RAP stage three report, at the SSEA Office on Fourth Street in Midland, is several inches thick and has documented greatly improved quality in Severn Sound but some challenges remain that are harder to control. Sherman says, "Severn Sound is a gateway to the Great Lakes, through the Trent-Severn Waterway and to the open waters of Georgian Bay. We have boats that people have purchased in Toronto or further south being transported here and sometimes we wonder if the boats are completely cleaned before they get here. It's also a federal harbour with ships coming in from the St. Clair-Detroit corridor into our waters and they're pumping ballast water in and out of those ships. We really are a gateway for invasive alien species."

The Severn Sound Environmental Association remains constantly vigilant at that gateway on our behalf to ensure clean water and a vibrant, diverse ecosystem are our children's inheritance. If you want to report something unusual on our waterways, like an algae bloom or dead fish, call the SSEA at 705-527-5166. For more information on stewardship programs, upcoming events or to make a donation to the SSEA visit www.severnsound.ca.