Florida Bay Project Profiles: Increased Salinity in Florida Bay

Question: Are salinity increases in Florida Bay the result of natural climatic cycles or the diversion of freshwater from man-made structures upstream?

Project: Sediment cores were collected from central and northeastern Florida Bay. Each layer of sediment was chemically dated and sorted for fossil remains. Scientists looked for ‘indicator species’ of groups such as ostracods (distant cousins to crabs), to infer the salinity at the time the animals were alive. The ostracod shells were also analyzed for calcium carbonate, magnesium, sodium and strontium. These analyses provide an additional means to estimate the past salinity history.

Findings to Date: Prior to 1940, salinity swings of 20 to 35 parts of salt per thousand (ppt.) occurred in central and northeastern Florida Bay. The patterns seen in the salinity data indicates a 6-year rain and drought cycle thought to be associated with El Ni–o and La Ni–a events. Additionally, there appears to be a 13-year cycle in salinity driven by an unknown climatic factor not related to El Ni–o.

Post 1940, the frequency and amplitude of the Bay’s salinity has increased. It is now common to find a salinity range from 20 to 45 ppt. with episodes as high as 60 ppt. These extremes in salinity have caused the local extinction of several species in the Bay.

The increase in Florida Bay’s salinity level is attributed to human activities directly and indirectly. Locally, the 1940’s correspond with major ecosystem changes in the diversion of freshwater via the construction of canals in South Florida. Indirectly, and on a larger scale, the 20th Century has seen human induced climate changes related to ‘global warming.’ These global changes in the atmosphere have the potential to alter the El Ni–o cycles that affect the Florida Bay ecosystem.

Status: Ongoing, results will be finalized in 2000.

Restoration Impacts: Provides resource managers with an overview of the natural range of salinity levels in Florida Bay’s past.

Funding Source: United States Geological Survey

Related Profiles:

• FBPP-09 • FBPP-108

• FBPP-145 • FBPP-147

• FBPP-149 • FBPP-150

February 04, 2012 This page last modified: July 16, 2001
February 04, 2012 This page last modified: July 16, 2001	*PALEOECOLOGY* Increased Salinity in Florida Bay - Nature or Man? Florida Bay Project Profile - 142 *Question:* Are salinity increases in Florida Bay the result of natural climatic cycles or the diversion of freshwater from man-made structures upstream? *Project:* Sediment cores were collected from central and northeastern Florida Bay. Each layer of sediment was chemically dated and sorted for fossil remains. Scientists looked for ‘indicator species’ of groups such as ostracods (distant cousins to crabs), to infer the salinity at the time the animals were alive. The ostracod shells were also analyzed for calcium carbonate, magnesium, sodium and strontium. These analyses provide an additional means to estimate the past salinity history. *Findings to Date:* Prior to 1940, salinity swings of 20 to 35 parts of salt per thousand (ppt.) occurred in central and northeastern Florida Bay. The patterns seen in the salinity data indicates a 6-year rain and drought cycle thought to be associated with El Ni–o and La Ni–a events. Additionally, there appears to be a 13-year cycle in salinity driven by an unknown climatic factor not related to El Ni–o. Post 1940, the frequency and amplitude of the Bay’s salinity has increased. It is now common to find a salinity range from 20 to 45 ppt. with episodes as high as 60 ppt. These extremes in salinity have caused the local extinction of several species in the Bay. The increase in Florida Bay’s salinity level is attributed to human activities directly and indirectly. Locally, the 1940’s correspond with major ecosystem changes in the diversion of freshwater via the construction of canals in South Florida. Indirectly, and on a larger scale, the 20th Century has seen human induced climate changes related to ‘global warming.’ These global changes in the atmosphere have the potential to alter the El Ni–o cycles that affect the Florida Bay ecosystem. *Status:* Ongoing, results will be finalized in 2000. *Restoration Impacts:* Provides resource managers with an overview of the natural range of salinity levels in Florida Bay’s past. *Funding Source:* United States Geological Survey *Related Profiles:* • FBPP-09 • FBPP-108 • FBPP-145 • FBPP-147 • FBPP-149 • FBPP-150
	The Florida Bay Education Project is an archived site. For more information go to NOAA's South Florida Ecosystem Education Project at www.aoml.noaa.gov/sfp/outreach.shtml.

PALEOECOLOGY

Increased Salinity in Florida Bay - Nature or Man?