Over a four-year period, two Georgia Southern professors and their graduate students conducted experiments with non-toxic dye and satellite-linked drifters to see where solid and dissolved objects go once they are placed into the Altamaha River.
It turns out, they can go quite far.
“The nutrients that come from the river are great, but the dissolved chemicals are what can hurt these delicate ecosystems,” said Daniel Gleason, one of the GSU professors, in a statement. “For example, when parked cars drip oil, that oil runs off and eventually ends up in the river system. Components of that oil can be taken offshore by streams and rivers. Just because you seem a long way from these ecosystems doesn’t mean you don’t have a significant impact on them.”
The study, conducted in cooperation with the Gray’s Reef National Marine Sanctuary and funded in part by a grant from the state Department of Natural Resources, showed the dye moved a significant distance into the ocean, including hitting the Gulf Stream, heading up the coast and then further out to sea.
During periods of heavy rain, materials contained in the river drift further out in the ocean, but during low-flow times, the study found those materials drifted south along the coast, and in particularly dry periods, they can even go back inland.
“We learned some really important information from this study,” said GSU professor Risa Cohen in “Connections,” a short film about the project. “We learned that it matters what season we’re talking about. The other thing we learned is that these substances move really far. So, Gray’s Reef is almost 40 kilometers off shore. CAT Reef is almost 50 kilometers from the drop site. So, these substances have the potential to move really far distances and affect habitats that are very far away from where they’re originating.”