DAPHNE, Ala. (WKRG) — A jubilee off the coast of Daphne is always a rare sight to see, but even more rare, photos taken by citizen photog Frank Potter.
The Mobile Bay National Estuary Program says the alligator was eating a flounder during a Jubilee yesterday in Daphne! Coastal Alabama is one of the only places in the world where you could witness an event like this.
The following was sent by the Mobile Bay NEP:
SO JUST WHAT IS A JUBILEE? Here is— THE MARINE AND WEATHER SCIENCE— behind the unusual events:
Jubilees are caused primarily by the upward movement of oxygen-poor (hypoxic) bottom waters that force bottom-dwelling creatures ashore. Bottom water low in oxygen results from several circumstances that happen at the same time. Pockets of salty water accumulate in the deeper parts of Mobile Bay and stagnate during calm conditions during summer months. Then stratification, or the layering effect of water containing different levels of salt, occurs when dense salty Gulf water is overlain by less dense, freshwater from the rivers. When water is stratified or layered in this way, the layers don’t get mixed, preventing the movement of oxygen from the air down into the bottom water layer.
Water temperature also influences the stratification of the water and is an important cause of a jubilee event. Warm water holds much less oxygen than cooler water. The shallow depth (average depth 10ft) of Mobile Bay causes the water temperatures to get very high in the summer months. This is the primary reason why jubilees only occur in summer.
Phytoplankton, (plant plankton), also play an important role in the occurrences of jubilees. Plankton, along with other microorganisms, form the base of the estuarine food web that feeds many larger organisms in the Bay. However, when an abundant supply of nutrients, such as animal wastes and fertilizers, get washed into the bay by rain, the phytoplankton population can increase drastically. At night, phytoplankton are unable to carry on photosynthesis and must take in tremendous quantities of dissolved oxygen from the water in order to sustain them. The more phytoplankton in the water, the more dissolved oxygen gets taken out of the near-surface water at night. This can cause the water near the surface to become depleted of dissolved oxygen.
Normally, the worst oxygen-poor water remains at greater depths within Mobile Bay. However, if a gentle easterly wind creates a surface current, it will move the surface layer of water from east to west, from near shore to offshore. As a result, the oxygen-poor bottom water gets pushed shoreward by a rising or incoming tide from the Gulf of Mexico.
As this tide-driven, salty, low-oxygen water moves shoreward, sea creatures in its path are “driven” in front of it. Animals that are good swimmers can easily swim over the top of the advancing low-oxygen water mass, but the slower paced organisms, such as crabs and flounder, must flee toward the shore (away from the low-oxygen water) as they try to get oxygen from the shallow water nearer the water’s surface. If the water near the surface is also depleted in oxygen, the animals are in big trouble.
For more information on the phenomenon of Jubilees, visit https://coast.noaa.gov/…/the-jubilee-phenomenon-teacher…
As one of the many pieces of our work, the MBNEP contracted Thompson Engineering to help create a detailed scientific Plan for the preservation and restoration of our coastal waters and way of life on the Eastern Shore. Citizen feedback is crucial in the creation of our Plan. If you care about the Eastern Shore and its waters and would like to include your input, please visit: https://www.mobilebaynep.com/news/the-eastern-shore-an-ecological-and-cultural-treasure-and-our-plan-to-protect-it