It turns out that glyphosate contributes phosphorus to algae in watersheds and thus feeds algal blooms which are often harmful to many life forms. Here's an article (August 21, 2018) from TCPalm.com in Florida on the runoff from Lake Okeechobee that is ruining Florida's Treasure Coast. Quoting one earth scientist (Univ. of Toronto): "Glyphosate ... has been used heavily in the agricultural areas around Lake Okeechobee and upstream in the Kissimmee River watershed for at least 25 years. Glyphosate provides a source of phosphorus for blue-green bacteria and recent research by others suggest that glyphosate enhances the growth of blue-green bacteria, which become tolerant and absorb glyphosate directly."
Bad news for the marine trophic chain, where glyphosate-laden algae will be processed upward into creatures higher in the chain, as this is how biology works. See Dr. Stephanie Seneff's work on glyphosate masquerading as the amino acid glycine in our own tissues here.