Hey There!
Here is an update about what's going on with our buoys! We are planning to release them later this week if the weather permits, which it hasn't seemed to want to lately, so fingers crossed it will cooperate soon. We are going to load Crystal, Big Boy, and Wilson onto a boat at Jacksonville University, and head down the St. Johns towards the outlet that leads to the Atlantic Ocean. The St. Johns Sea Buoy is about 4 miles from the outlet and this is where we will say goodbye to our buoys. They will be missed but we know that they are onto bigger and better things! We are releasing them at this location in order to pass all of the incoming and outgoing boat traffic and to ensure that our buoys will not get demolished upon release.
The St. Johns is the longest river in Florida and the second longest along the Atlantic coast. As a river one of its most unique characteristics is that it flows northward. It is a very lazy river with a flow rate of only 0.3 mph. (Demort, 1991) It has both freshwater and brackish qualities thus making it the home of both marine and fresh water organisms. (Johnson, 1996) With the approval of the US Army, the city of Jacksonville wants to dredge the mouth of the St. Johns and continue down into the city in order to make shipping easier and more productive. The dredging has not taken place yet and has been a controversial issue for years. The US Army supports the project and claims that since the dredged material is being relocated to restore a nearby salt marsh, the project is actually beneficial to the environment. (Dept. of Army, 2012) However, when a river is dredged it stirs up the toxicity from the benthic layer completely altering the chemical makeup of the river. The slow flow rate of the St. Johns makes these toxic effects even more detrimental to the rivers ecosystem, since it would be that much more difficult to flush out the pollutants. (Sturve, 2005) This habitat alteration not only negatively effects all of the organisms living in the benthic layer of the river, but even the fish and sharks are at great risk.
Sharks that can thrive in both fresh and salt water environments, or Euryhaline Elasmobranchs, can vary in their characteristics. Some can reproduce and inhabit freshwater completely, while others, like the bull shark, prefer to reproduce solely in brackish water and not inhabit the area. The St. Johns is the perfect environment for bull shark nurseries and the perfect habitat for a variety of other marine species. (Johnson, 1996) (Curtis, 2013) Sharks are an important apex predator, and keeping shark and fish populations balanced in estuarine communities like the St. Johns is crucial. Dredging will alter many of these species habitats and may leave the St. Johns ecosystem in complete disarray. (Curtis, 2013)
Just as bull sharks fill rivers like the St. Johns, tiger sharks and great whites surround the oceanic coastline, and these massive animals tend to really love our Jacksonville coast! Located slightly North East of our buoy release sight near the St. Johns Sea Buoy, a 12'2" 800 pound mature tiger shark named Bailey recently pinged on February 3rd. An even larger female shark named Katherine, a 14'2" 2,300 pound immature great white shark, pinged just North of Fernandina Beach on February 5th! Katharine is a female great white shark who was first tagged off the coast of Cape Cod, Massachusetts on August 20, 2013. Since then she has migrated up and down the East Coast and into the Gulf of Mexico. I'm sure this will not be the last we see these two large ladies and we will keep you all updated with any more sharks our buoys might rub elbows with!
Photo: Katherine's whereabouts around our coast.
Photo: Here is Katherine, the 14'2'' 2,300 pound great white shark!
COOL FACT: Around 2 million years ago fluctuations in the climate produced multiple ice ages, causing sea levels to rise and fall. As the sea level dropped, water trapped behind a long barrier island formed brackish lagoons that began flowing north, forming the St. Johns River. (theriverreturns.org)
References:
Curtis, T. H., Parkyn, D. C., & Burgess, G. H. (2013). Use of human-altered habitats by bull sharks in a Florida nursery area. Marine and Coastal Fisheries,5(1), 28-38.
DeMort, C. L. (1991). The St. Johns River System. In The rivers of Florida (pp. 97-120). Springer New York.
Department of Army (PDF) - http://www.saj.usace.army.mil/Portals/44/docs/Navigation/FINAL_Jacksonville_Harbor_Mile_Point_Navigation_Study.pdf
Johnson, M. R., & Snelson Jr, F. F. (1996). Reproductive life history of the Atlantic stingray, Dasyatis sabina (Pisces, Dasyatidae), in the freshwater St. Johns River, Florida. Bulletin of Marine Science, 59(1), 74-88.
Sturve, J., Berglund, Å., Balk, L., Broeg, K., Böhmert, B., Massey, S., ... & Förlin, L. (2005). Effects of dredging in Göteborg Harbor, Sweden, assessed by biomarkers in eelpout (Zoarces viviparus). Environmental toxicology and chemistry, 24(8), 1951-1961.
Shark Tracker - http://www.ocearch.org/#SharkTracker