Florida Bay Project Profiles: Seagrass Dieoff in Florida Bay

January 07, 2009

This page last modified:
July 16, 2001

Seagrass Ecology

Seagrass Dieoff in Florida Bay

Florida Bay Project Profile - 1

Question: Are thick beds of turtle grass (Thalassia testudinum) dying as the result of high salinity?

Experiment: From 1989 to 1995, eight areas of turtle grass beds were measured each season for water column temperature and salinity, as well as, how well the seagrasses were growing, and how many there were. Five of these stations had experienced high turtle grass dieoff of the 1980's and three were relatively healthy beds used as control sites.

Findings: Season and salinity played a significant role in the health and abundance of turtle grass beds. During times of higher salinities, such as late summer, there was a significant depression in turtle grass growth. However, during the spring to fall there was greater than average growth in the turtle grass beds and likewise, from the fall to winter there was less than average growth. Salinities within the water were much higher in the earlier years (46ppt) and decreased over the course of the project (29-38 ppt). The sites within western Florida Bay had the largest dieoff, but some of the thicker beds in the eastern Bay suffered dieoff as well. The highest recorded temperatures were during the years of the dieoff.

It appears that the seagrass dieoff of the 1980's is not the same as the dieoff of the 1990's. The seagrass dieoff is thought to have occurred in three phases: Developmental, Initiation and Continuation. Briefly, the Developmental Phase was created by environmental and man made conditions that resulted in high salinities and dense beds of turtle grass. The Initiation Phase of dieoff was the result of multiple stresses including hot, extra salty waters, increased sulfides in the sediments, and possibly an infection by slime mold. In the Continuation Phase, turbidity and algae blooms in the water column continue to reduce the light needed for the seagrasses to photosynthesize causing more to die.

Status: Ongoing

Restoration Impacts: From this work, restoration managers began to focus on controlling the timing and distribution of freshwater into the Everglades watershed.

Funding Sources: Barley Scholars Endowed, University of Virginia, Past: NPS, Florida DEP

Other Related Profiles:

FBPP - 06
FBPP - 10
FBPP - 12
FBPP - 17

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.

January 07, 2009 This page last modified: July 16, 2001
January 07, 2009 This page last modified: July 16, 2001	*Seagrass Ecology* Seagrass Dieoff in Florida Bay Florida Bay Project Profile - 1 *Question:* Are thick beds of turtle grass (Thalassia testudinum) dying as the result of high salinity? *Experiment:* From 1989 to 1995, eight areas of turtle grass beds were measured each season for water column temperature and salinity, as well as, how well the seagrasses were growing, and how many there were. Five of these stations had experienced high turtle grass dieoff of the 1980's and three were relatively healthy beds used as control sites. *Findings:* Season and salinity played a significant role in the health and abundance of turtle grass beds. During times of higher salinities, such as late summer, there was a significant depression in turtle grass growth. However, during the spring to fall there was greater than average growth in the turtle grass beds and likewise, from the fall to winter there was less than average growth. Salinities within the water were much higher in the earlier years (46ppt) and decreased over the course of the project (29-38 ppt). The sites within western Florida Bay had the largest dieoff, but some of the thicker beds in the eastern Bay suffered dieoff as well. The highest recorded temperatures were during the years of the dieoff. It appears that the seagrass dieoff of the 1980's is not the same as the dieoff of the 1990's. The seagrass dieoff is thought to have occurred in three phases: Developmental, Initiation and Continuation. Briefly, the Developmental Phase was created by environmental and man made conditions that resulted in high salinities and dense beds of turtle grass. The Initiation Phase of dieoff was the result of multiple stresses including hot, extra salty waters, increased sulfides in the sediments, and possibly an infection by slime mold. In the Continuation Phase, turbidity and algae blooms in the water column continue to reduce the light needed for the seagrasses to photosynthesize causing more to die. *Status: Ongoing Restoration Impacts:* From this work, restoration managers began to focus on controlling the timing and distribution of freshwater into the Everglades watershed. *Funding Sources:* Barley Scholars Endowed, University of Virginia, Past: NPS, Florida DEP *Other Related Profiles:* FBPP - 06 FBPP - 10 FBPP - 12 FBPP - 17
	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.