Salinity data on storm effects (Robblee) First Seagrass Die-off Observations Zieman et al. Conceptual Model of Die-off For full Page view of Model Click Here Photos of new die-off in JKB Full page view of Carlson and Durako Die-Off Model SPOT image of Blooms (Butler) photomicrograph of Synecoccuss

December 1994

 Distribution of H. engelmannii in JKB Banktop Die-Off photo (Carlson) Banktop die-off study figures (Carlson & Blakesley) Need Image of Hurricane Georges Barnes Key Die-off patch photos (Schwartzchild, Frankovich, Blakesley) We need link to pdf files of the papers (Fourqurean) Rudnick et al. measure nutrient fluxes in Little Madiera & Taylor Pond URL for  Everglades LTER (Fourqurean) Aerial image (Carlson) Full page view of SRT meeting notes Full page view of Seagrass Modeler needs Question 4 Synthesis
This is where brief Text on significant events or observations will go Decline in Tortugas Shrimp landings SPOT image (left pane) shows no die-off  patch in Rabbit Key Basin.  Nor was die-off observable in Johnson Key Basin or Rankin Lake. "Potholes" observed in Thalassia beds near Rankin Lake and near Cross Bank by Backcountry fishing guides, Audubon field scientists, and Mike Robblee Tagged conch observed to die in Hawk Channel due to heat stress (Carl Berg FMRI); coral bleaching observed at Looe Key (Billy Causey); fish dying on Cross Bank (Jeff Holmquist and Mike Robblee) Hurricane Floyd passes over NE Florida Bay, little wind effects, but high rainfall Mike Robblee observes die-off patches along north shore of Johnson Key Basin Fishing guide (Dr. Roy Crabtree) contacts Dr. Susan Bell (USF) in March regarding dying seagrasses in northern Florida Bay bights.  Bell contacts Hall and Durako, Durako calls Robblee and Zieman Photoquad of a die-off patch in Johnson Key Basin Phytoplankton bloom observed northeast of Long key

Lesions observed on Thalassia leaves at die-off sites

 SPOT imagery shows spread of large die-off area in Rabbit Key Basin.  Paired images (February 2, 1987-June 1988) indicate rapid spread of die-off.

George Powell (Audubon) writes letter to Nat Reed regarding die-off. 		C-111 plug removed, large release of freshwater, salinity drop in NE Bay results in defoliation of seagrasses and fish kills. Karl Lessard reports on "Dead Zone" west of Everglades National Park.  Macro-algal Bloom west of Florida Bay suggests a larger-scale process may be involved in changes observed within Florida Bay Mike Robblee observes a rapid die-off in Sunset Cove, adjacent to ENP Key Largo Ranger Station where ENP research vessels are moored. Estuarine Research Federation Biennial meeting has special session on seagrass die-off in Florida Bay.

 Special Issue of Bulletin of Marine Science volume 44 on Florida Bay.

 NMFS Shrimp Workshop

Concerns grow over effects of prolonged hypersalinity in central Florida Bay

 Coral bleaching event - larger than 1980s event (Billy Causey) Mangrove die-off first observed at Dump Keys - central Florida Bay

Black Mullet observed feeding in patchy seagrass beds in western Florida Bay		 First map of distribution and extent of die-off published

Earliest observation of persistent turbidity in Johnson Key Basin caused by tidally resuspended sediments (Kuss and DiDomenico, ENP)

 Active die-off observed again in Johnson Key Basi Carlson and Durako conceptual model of seagrass die-off produced in CZM final report. Initiation of phytoplankton blooms (November 1991) Hurricane Andrew passes over south Florida

High rainfall a week to 10 days following Andrew washes mangrove detritus into Florida Bay.

Major turbidity plume from western Florida Bay reaches Big Pine Key on December 22, 1992.

 Widespread turbidity persists from 1991-1995 results in much speculation on how much seagrass has been lost.  One report states 100,000 acres have died.

Thalassia observed dying in deeper channels oceanside of Keys following phytoplankton blooms

 Special issue of Bulletin of Marine Science on Symposium on Florida Keys Regional Ecosystem, November 1992 is published. Spring and summer of 1995 wettest in 30 years. Florida Bay becomes a truly estuarine system.  Halophila engelmannii first observed in Johnson Key Basin - along with dominance of Halodule in this basins suggests a change to a shade-adapted community.

Madden (SFWMD) and Koch (FAU) observe rapid defoliation near Crocodile point following January cold front.

 Salinity patterns indicate more estuarine conditions exist during fall, especially Fall 1995 and 1997.
Turbidity chronic and widespread in western basins.

A population explosion of sea urchins observed SW of Florida Bay.

 Water clarity begins to improve within Florida Bay (spring 1997, spring 1998, spring 1999.

 

 Flowering of Thalassia observed in several FHAP basins. 

Halodule flowers and fruits observed in FHAP core samples for the first time.		 Hurricane Georges passes west of Florida Bay - observations indicate that only old leaves are removed from Thalassia, however, Halophila engelmannii is ripped up in many areas of Johnson Key Basin "Classic " die-off patches observed on bank edge east of Big Rabbit Key

Barnes Key eastern bank and basin have extremely dense Thalassia clear water and no evidence of die-off.

 New "Classic" die-off observed in Barnes Key area and in Sunset Cove (Art Schwartzchild, Tom Frankovich, and Jay Zieman, UVa) Flowering of Thalassia observed at 19 stations in 7 FHAP basins.  

Halodule flowers and fruits observed at 24 stations in 4 FHAP basins

 Dedicated  issue of  Estuaries  "Florida Bay:A Dynamic Subtropical Estuary" Volume 22(June 1999) is published.

The DERM monitoring program maps the die-off in Little Madiera

 Hurricane Irene passes west of Florida Bay    

Leaf defoliation observed in Little Madiera Bay following Irene.  Large area with no apparent Thalassia short shoots,  Halodule colonizing bare areas (Thalassia recovers by Feb-Mar 2000, Chris Madden SFWMD)

 Florida Coastal everglades LTER NSF-funded  Aerial transect of Barnes Key Die-off area

Flowering of Thalassia observed during spring 2000 FHAP sampling - things are still looking good

 Madden (SFWMD) and Burd (TAMU) begin USGS-funded seagrass process-based model. Seagrass Research Team (SRT) meets November 16-17 to discuss what we now know regarding die-off and seagrasses in Florida Bay

The SRT also list what data the Seagrass Modelers need 

 2001 Florida Bay Science Conference - Durako and Zieman present Synthesis on Question 4: What are the causes and mechanisms for the observed changes in seagrasses and hardbottom comunity of Florida Bay and adjacent marine systems?  What is the effect of changing salinity, light and nutrient regimes on these commuities?
 In the Beginning  (early 1900s)   1980s   1987-1989  February 2, 1987 Summer 1987 July 18, 1987  October 1987  November-December 1987  Spring 1988     1988 -  May 1988 Late Spring 1988  Summer 1988 Fall 1988 Winter 1988  January 1989  Summer 1989  Fall 1989     Summer/Fall 1990       Spring 1991 Summer 1991          August 1991  Fall 1991      Fall/Winter 1991 August 24, 1992            Spring/ Summer 1993              Fall 1993               Summer 1994               Spring 1995                  Summer 1995            Fall 1996             Summer 1997            Fall 1997               Winter 1997                  Spring 1998      September 25, 1998   Fall 1998     January 1999        SSpring 1999        Summer 1999            Fall 1999        October 15, 1999            January 2000      Spring 2000                Summer 2000                  Fall 2000  April  23-26, 2001
This is where brief text will go describing relevant research programs, publications, research results, and comments on these related to the conceptual models on seagrass changes in Florida Bay March 1986-September 1987 Clay Montague and Janet Ley sample 12 stations from Little Madiera Bay eastward J. W. Fourqurean Dissertation Research Guides meet Mike Robblee and Jim Tilmant (NPS) at Little Rabbit Key in April and observe rotting rhizomes and extensive die-off

Water Quality monitoring initiated in Florida Bay
25 stations Fourqurean 1988/89 (NPS-funded)
Jones (FIU) SERP starts 1990 (NPS-funded initially, then SFWMD)

 Paul Carlson and Michael Durako (FMRI  survey Johnson Key Basin (JKB) and establish sampling stations.  Zieman surveys Rankin Lake and JKB Memo from Robblee to ENP Superintendent Finley regarding seagrass die-off leads to initial funding to investigate this phenomenon. Zieman report to ENP warns of potential wide-spread turbidity and nutrient release from sediments in die-off areas Robblee initiates permanent quads and swimovers.
Carslon initiates studies on hypoxia
Durako initiates studies on structure and dynamics
Porter and Muehlstein sample die-off areas for microbes		 Porter, Carlson, and Durako verify Koch's Postulates using leaf clamp experiments.  Thalassia leaf segments infected with Labyrinthula always induce lesions on Thalassia seedlings Zieman initiates long-term Thalassia productivity stations near 4 core die-off areas Nance 1989. NMFS Report
Pete Sheridan (NMFS) initiates shrimp work in Florida Bay		 Gordon Thayer (NMFS) initiates studies on plant responses to die-off.

Jay Bugden (FIU) thesis on microbial communities associated with die-off.		 Paul Carlson (FMRI) Mangrove die-off study (CZM-funded), aerials, permanent quads, historical change analysis

Paul Carlson finds increased mortality of Thalassia in perfusion experiments with added glucose (high H2S).

First paper describing the die-off is published in Marine Ecology Progress Series.

 Tom Frankovich (UVA) initiates epiphyte study (ENP& SFWMD-funded)

Carlson conducts first bucket experiments with elevated sulfide 

 Durako and Kuss examine effects of Labyrinthula infection on Thalassia photosynthesis in Rankin Lake and Sunset Cove
 Phlips reports on extent of  blooms, primarily cyanobacteria,  Synecoccus spp.
Butler et al  reports on sponge mortality and other secondary effects of the cascading decline in Florida Bay
NOAA conducts aerial overflights of Florida Bay		 BioScience paper on effects of Hurricane Andrew Zieman et al. investigate light-reduction effects on Thalassia in Rabbit Key Basin and Sunset Cove (USEPA-funded) Lee Hefty et al. (DERM) initiate seagrass monitoring of northeastern basins.  Penny Hall et al. (FMRI) sample 107 stations previously sampled by Fourqurean and Zieman in 1983/84.  Both Thalassia and Halodule distributions declined over the 10 year period. Durako and Hall (FMRI) initiate the Fish Habitat Assessment Program (FHAP) and produce first  maps of seagrass abundance.  

Landsberg and Blakesley (FMRI) initiate spatial and temporal study of Labyrinthula distribution from FHAP samples.

 Rudnick et al. (SFWMD) measure nutrient fluxes in seagrass beds.

Montague and Chipouras (UFL) initiate field studies along northern Florida Bay		  David Rudnick (SFWMD) drafts Pre-Die-off and Post Die-off conceptual models of seagrass die-off that incorporate two previous models, water management, and higher trophic level effects. Rick Stumpf (USGS) examines satellite imagery (AVHRR) to detect changes in seagrass abundance from 1986-1997.

Thalassia abundance declines while Halodule abundance increases in Johnson Key Basin

  Carlson and Blakesley (FMRI) initiate banktop die-off  studies.

Thalassia and Halodule abundances generally increasing

Ellen Prager produces benthic cover map for Florida Bay

 Fourqurean et al. (FIU) sample two sites in Rabbit Key Basin to examine scale-based variability in potential Thalassia ecoindicators (USEPA-funded)

Randy Chambers and Fourqurean study Fe, S, and P (ENP-funded)

 FHAP change maps indicate that the greatest losses of Thalassia, since 1995, are occurring in the western basins.

Madden et al. (SFWMD) begin collection of Thalassia data in NE Florida Bay.  They also create synoptic high-resolution maps of water quality conditions.

 Carlson (FMRI) conducts bucket experiments in Rabbit Key Basin.  Elevated sulfide treatments kill Thalassia.

Erskine and Koch conduct lab studies on Thalassia tolerance to sulfide (SFWMD-funded). 

 Madden (SFWMD), Kemp (U MD), and Gruber (SFWMD) begin development of spatially averaged Thalassia model for NE Florida Bay. Koch (FAU) measures P uptake and alkaline phosphatase activity in Thalassia

Madden and Cornwell (SFWMD) compare oxygen and nutrient fluxes in seagrass beds versus bare sediments.

 Carlson (FMRI) measures [H2S] in Barnes KEy die-off area

Hall and Blakesley (FMRI) establish permanent transects and quadrats to monitor changes in Thalassia and Labyrinthula at Barnes Key

 FHAP samples Johnson Key Basin before and after Irene.  Previously sparse Thalassia exhibits loss, dense beds unaffected.  Halophila is damaged and segments are observed floating in wrack. Hall et al. conduct "Mini-FHAP" sampling of Barnes Key Die-off area..

Peterson and Fourqurean Potential for filter-feeding organisms to influence water column characteristics  and feedbacks to seagrasses (FL SeaGrant)

Eric Bricker (UVA) begins an assessment of belowground productivity of Thalassia on Cross Bank and Rabbit Key Basin.

FHAP change maps indicate western basins lower in Thalassia  and much higher in Halodule abundance (up 450% in JKB & RBK and 200% baywide) relative to 1995

 Durako measures photosynthetic characteristics of Thalassia in situ at Sunset Cove and Cross Bank with PAM fluorometer. Leaves with lesion have lower photosynthetic yields, but close-interval measurements indicate lesion effects localized on leaf Durako measures photosynthetic characteristics of Thalassia in Rabbit Key in Carlson's buckets in situ with PAM.

FHAP fall 2000 Thalassia and Halodule distribution maps and fall 1995 versus fall 2000 change maps produced for Thalassia and Halodule

 Zieman, Borum monitor sediment O2 and [H2S] and Thalassia meristem O2 levels in Rabbit Key Basin and Barnes Key
Thumbnail Photos of sampling - link to upper panes Thumbnail of Data Figures - link to upper panes Comments relevant to conceptual models Montague & Ley 1993

Salinity variability more important than mean salinity to biota

Seagrass species composition and productivity

Sediment depth and P availability control seagrass density

 Hot, calm, and dry conditions, coral bleaching Zieman Visits Die-off observed in north-central Bay where seagrasses were dense Boyer et al., 1999 We need a map of WQ stations and figs on Chl a and Salinity trend lines

High salinity and low chlorophyll in 80s and early 90s

 Die-off has contagious distribution and sharp ecotone Labyrinthula is most common microbe at die-off sites Lesions evident at die-off sites C-111 release may have had a role in Sunset Cove die-off Leaf punch productivity measurements along transects Sampling porewater sulfide levels Sampling rhizome for hypoxic stress Labyrinthula the most common microbe associated with die-off sites  Labyrinthula causes leaf lesions observed at die-off sites Die-off in Sunset Cove suggests transmissable agent involved in die-off Figure of Tt productivity at long-term sites (Zieman) Decline in productivity at die-off sites indicates increasing stress Figure of shrimp landings (Robblee) @ high salinities shrimp can survive, but can't molt

Die-off patches change from Thalassia to Halodule-dominated

 Figure showing Seagrass changes (Thayer) Heterotrophs in water column are stimulated by seagrass die-off Robblee et al. 1991 Turbidity in western basins may have initiated secondary seagrass mortality Hypersalinity and pathogenic disease proposed as factors in die-off Epiphyte loads relatively low Bay-wide Bucket experiments indicate that elevated sulfide can kill Thalassia Labyrinthula infection triples respiration and results in no net photosynthesis Seagrass die-off leads to cascading declines in other biota Image of BioScience Paper (Zieman) Salinity data on Andrew effects (Robblee) Hurricane Andrew does not provide test for "Hurricane Hypothesis" Phytoplankton blooms and turbidity reduce light and lead to seagrass mortality Lower salinity basins have more Halodule and Ruppia than Thalassia 109 stations for Decadal (84-94) comparison

Figures from Hall et al. 1999

(Hall)

 Thalassia and Halodule distribution declined from 1984-1994 Thalassia the dominant species in 10 FHAP basins. Labyrinthula abundance decreases below 20 ppt. Nutrient flux Data (Rudnick et al, and Madden and Cornwall) Montague and Chipouras Field data figure (Chipouras) Nutrient fluxes are mediated by the presence of seagrass beds Click here for full page view of Rudnick Models

Reduced light in Johnson Key Basin results in shade-adapted community

 AVHRR imagery indicates loss of macrophytes west of  Florida Bay pre-1987 (Lessard's "Dead Zone"?)

 

 Increasing water clarity is coupled with increasing seagrass abundance Banktop die-off may not be coupled to basin die-off MultiScale Sampling Design Chambers & Fourqurean study figures (Fourqurean) Seagrass loss results in increased fluxes of nutrients to water column - this may allow phytoplankton blooms Bucket Experiment Figure (Carlson) Lab sulfide Figure (Koch) Field and lab studies conflict on role of sulfide in seagrass die-off

Click here for a full-window view of the Madden et al. Model

"Faux" die-off in Madiera indicates other types of mortality occurring in Florida Bay Barnes Key [H2S] figure (Carlson) Koch P uptake and APase figures (Koch)   The hypothesis that algal blooms were stimulated by release of nutrients from seagrass die-off is not likely to be true Halophila exhibits more damage from hurricane than Thalassia Dense Thalassia unnaffected by Irene, sparse beds exhibit loss of cover Labyrinthula lesions reduce photosynthetic Yields Elevated porewater sulfide reduces photosynthetic Yield Thalassia in die-off sites may suffer from meritstem death due to anoxia