Even 4 years later the results of Hurricane Michael are nonetheless evident across the Panhandle of Florida and past. The Category 5 hurricane that made landfall close to the Apalachicola River again in October of 2018 left a path of destruction behind it because it tore via the area. While the injury on land was straightforward to see by the flattened cities and forests, the destruction underwater was a bit extra hidden. A research by researchers on the University of Georgia with the U.S. Fish and Wildlife Service has not too long ago proven what extent the injury was to the river within the aftermath of Hurricane Michael. These outcomes have been revealed within the December challenge of Transactions of the American Fisheries Society, displaying the hurt to gulf sturgeon.
Due to a long-term and ongoing mission within the Apalachicola River in monitoring gulf sturgeon (Acipenser oxyrhynchus desotoi). Scientists with the UGA Warnell School of Forestry and Natural assets have been in a position to make a timeline of what occurred within the river, the oxygen ranges, circulate charge, and the destiny of the sturgeons who both escaped up the river or into the Gulf of Mexico. All of this knowledge was collected by particular tags on the fish being tracked by tools that survived the storm, and climate stations and tide gauges reporting the water situations and circulate.
“We had a couple different metrics for ‘before’ adult population estimates, and there’s also monitoring for other [sturgeon] in all the rivers nearby, so we would know if they went into other rivers,” mentioned Adam Fox, an assistant analysis scientist at Warnell and co-author of the research. “So, all of that gave us information that we saw a decline of 36% to 60% of the adult fish compared to pre-storm estimates.”
The sturgeons are a federally listed protected species, that after spanned from Tampa Bay to New Orleans. But now they solely have small populations in solely seven rivers, with the biggest populations within the Suwanee and Apalachicola rivers. During regular situations, the Apalachicola River often has an oxygen vary of 4 to six milligrams per liter. But proper after Hurricane Michael the oxygen ranges dropped to close zero and stayed that manner for nearly a month. The nutrient flush that occurred from all of the particles and sewage reaching the river precipitated these anoxic water situations.
There is a inhabitants estimate of round 1,000 grownup fish within the river, and because of the water situation post-hurricane, the scientists estimate a lack of between 30% to 60% of the grownup inhabitants.
“This is obviously very concerning, especially because with climate change, hurricanes are supposed to increase with frequency and intensity,” mentioned Fox, noting that hurricanes traditionally have hit the western parts of the panhandle—areas the place gulf sturgeon have struggled for generations.
But then Fox and the research’s lead writer, 2021 Master of Science graduate Brendan Dula, realized one other facet of the sturgeon inhabitants nonetheless hadn’t been accounted for.
“Because if the adults were dying, we thought we were probably going to lose an entire juvenile year class,” he added. After hatching additional upstream, juvenile sturgeon spend the primary couple years of their life in estuaries—not fairly the gulf, however not fairly the river.
By the time of landfall of Hurricane Michael the group solely had 5 tagged juvenile sturgeon, and all of them disappeared after the hurricane. But the subsequent 12 months surprisingly there have been some good indicators for the sturgeon inhabitants.
“We actually had more ‘age 1’ fish than we’d had in the years before the storm. And so somewhere upriver they found some sort of refuge. Probably, we think, below Jim Woodruff Lock and Dam where water may have been better oxygenated,” mentioned Fox. “Gulf sturgeon spawn in the spring, but there’s growing evidence that sometimes they also spawn in the fall. Spawning is also related to flow, and so high flow from the river may have made for a successful fall spawn.”
Despite laying as much as 400,000 eggs annually per fish, solely about 50 offspring sometimes survive to age 1 annually within the Apalachicola River. But within the years since Hurricane Michael, the variety of juveniles annually is now over 100.
“They’re very sensitive to a lot of things and have a slow maturation—between 8 and 15 years. So, if adults are harvested or killed by hurricanes, that has huge impacts down the road,” mentioned Fox. “But as long as there’s some sort of refuge for them, the next generation may survive. It may take a while before they can spawn on their own, but at least they’re around.”
