I have been in contact with a producer for a Ecklonia maxima fertilizer, they state that no quantitative data on DMT in E. maxima is published, not even in the paper linked to in my last post. So if this really is a potential source or not is unknown, perhaps someone with extensive knowledge should order the fertilizer and do a test extraction?

I don't want to do this, as I have no idea if the other substances will survive the extraction, and in that case if they can pose any threat when concentrated. Although I very strongly doubt that it is toxic, as the fertilizer is dried and then fed to animals without even one published report of toxicity.