An experimental project in which 100 tonnes of an iron-rich dirt-like material were dumped into the ocean off B.C.'s north coast is sparking controversy.

The fine brown material was dumped about 300 kilometres west of the islands of Haida Gwaii in a process called ocean fertilization.

The $2-million project, initiated by the Haida Salmon Restoration Corp., is intended to raise nutrient levels offshore in hopes of reviving salmon populations, according to corporation president John Disney.

Disney said earlier reports that iron sulphate was used in the dump were incorrect, and that a finely ground dirt-like substance with trace amounts of iron was actually used.

"The results were just spectacular, like we created life where there wasn't life," Disney said.

The dumping created a bloom of phyto-plankton, plants at the base of the food chain that are eaten by other creatures.

Theoretically, it could also help pull carbon dioxide, responsible for climate change, out of the atmosphere.

• CBC's Quirks and Quarks speaks to a scientist about iron fertlization in the oceans

But the project is ringing alarm bells in the scientific community, because the bloom it created spread 10,000 square kilometres and was visible from space.

Some experts also dispute the purported benefits of ocean fertilization for marine ecosystems.

Oceanographer says process 'scares me'

“It scares me,” said Maite Maldonado, a biological oceanographer at the University of B.C. who specializes in the impact of trace minerals on ocean life.

"If you have a massive bloom or growth of this microscopic algae, you might not have enough oxygen in the water column at certain depths."

Maldonado said the process could have effects that are the reverse of those intended, as the lack of oxygen could potentially create toxic, lifeless waters.

The project is 100 times larger than any of the previous experiments in iron fertilization, she said.

“We have to be very careful about doing this without having a full understanding of how the ecosystem as a whole is going to respond.”

But Disney said all the results of the experiment so far have been positive, and the corporation promises to disclose the results of their project to critics.

With files from the CBC's Greg Rasmussen and Marissa Harvey