Hall - Techniques to enhance recovery rate of prop scars
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Hall - Techniques to enhance recovery rate of prop scars
Developing Techniques to Enhance the Recovery Rates of Propeller Scars in Turtlegrass (Thalassia testudinum) Meadows Final Report to USFWSMargaret o. Hall - Techniques to enhance recovery rate of prop scars Hall1, Manuel Merello1, w. Judson Kenworthy2, Donna Berns1, Keri Ferenc1. Jennifer Kunzelman1. Farrah Hall1, and Jitkya Hyniova1’Florida Fish and W ildlife Conservation Commission Florida Fish and Wildlife Research Institute 100 Eighth Ave. S.E.St. Petersburg, Florida 337012Center for Coastal Fishe Hall - Techniques to enhance recovery rate of prop scarsries and Habitat Research NCCOS, NOS, NOAA 101 Plvers Island Road Beaufort. North Carolina 2851638777File Code: F2319-02-F1FINAL REPORTGRANT TITLE: DeHall - Techniques to enhance recovery rate of prop scars
veloping Techniques to Enhance the Recovery Rates of Propeller Scars in Turtlegrass (Thalassia testudiniun) Meadows.STATE: FloridaGRANT NUMBER: R-4PERDeveloping Techniques to Enhance the Recovery Rates of Propeller Scars in Turtlegrass (Thalassia testudinum) Meadows Final Report to USFWSMargaret o. Hall - Techniques to enhance recovery rate of prop scarsSeagrasses form some of the world's most productive marine plant communities, and Florida’s estuaries and nearshore coastal waters contain the nation’s greatest seagrass resources (> 2.5 million acres: Sargent et al. 1995). Seagrasses provide food and or shelter to numerous commercially and recreati Hall - Techniques to enhance recovery rate of prop scarsonally important fish and invertebrate species including spotted seatrout, tarpon, pink shrimp, and spiny lobster (Zieman and Zieman 1989). A varietyHall - Techniques to enhance recovery rate of prop scars
of wading birds, as well as endangered species such as bald eagles, manatees, and sea turtles also depend, in pan, on seagrass communities (Fonseca 19Developing Techniques to Enhance the Recovery Rates of Propeller Scars in Turtlegrass (Thalassia testudinum) Meadows Final Report to USFWSMargaret o. Hall - Techniques to enhance recovery rate of prop scarses in seagrass acreage have occurred worldwide, and Florida is no exception. Approximately 35% of the seagrasses historically present statewide have been lost, and declines are much higher in some systems (e.g. > 80% decline in Tampa Bay; Lewis et al. 1985). Although natural events such as severe st Hall - Techniques to enhance recovery rate of prop scarsorms or disease are sometimes responsible for damage to seagrass habitats, the vast majority of seagrass loss is related to human activities (Short anHall - Techniques to enhance recovery rate of prop scars
d Wyllie-Escheveria 1996). Recent assessments of human impacts to seagrasses have focused principally on indirect causes of decline (e.g. reduction inDeveloping Techniques to Enhance the Recovery Rates of Propeller Scars in Turtlegrass (Thalassia testudinum) Meadows Final Report to USFWSMargaret o. Hall - Techniques to enhance recovery rate of prop scarseagrasses in many locations are suffering extensive physical damage from watercraft.File Code: F2319-02-Fparticularly from propeller scarring. Propellers damage seagrass beds by ripping up shoots and rhizomes. When the propeller penetrates the sediment, a long, narrow gap, or prop scar, is created i Hall - Techniques to enhance recovery rate of prop scarsn which scagrass density and biomass arc severely reduced or completely removed. A typical prop scar created by a small vessel (< 6.5m in length) is aHall - Techniques to enhance recovery rate of prop scars
pproximately 0.25-0.50m wide and 0.1-0.5m deep. Larger vessels (> 6.5m in length), especially those with twin propellers, can produce substantially-wiDeveloping Techniques to Enhance the Recovery Rates of Propeller Scars in Turtlegrass (Thalassia testudinum) Meadows Final Report to USFWSMargaret o. Hall - Techniques to enhance recovery rate of prop scarsthey occur at depths well within reach of boat propellers. The majority’ of seagrasses in Florida occur in water depths less than 2m. consequently, nearly all Florida seagrass beds show damage caused by' boat propellers (Sargent et al. 1995). If boating activities are locally intense, propeller scar Hall - Techniques to enhance recovery rate of prop scarsring may' be a major source of habitat destruction. Sargent et al. (1995) reported that the greatest acreage of moderate and severe propeller scar damHall - Techniques to enhance recovery rate of prop scars
age occurred in regions with the densest populations and the most registered boats (e.g. Florida Keys. Biscayne Bay, Tampa Bay, Charlotte Harbor, nortDeveloping Techniques to Enhance the Recovery Rates of Propeller Scars in Turtlegrass (Thalassia testudinum) Meadows Final Report to USFWSMargaret o. Hall - Techniques to enhance recovery rate of prop scarsregrowth of seagrasses from propeller damage can lake many years (Zieman 1976. Durako cl al. 1992. Dawes cl al. 1997). The actual recovery' time is influenced by such factors as the physical conditions at the site (e.g. hydrodynamic regime, sediment composition, water clarity ) and the amount of sea Hall - Techniques to enhance recovery rate of prop scarsgrass damage. Once a propeller scar is created, wave action or fast moving currents can lead to erosion within the scar, resulting in scouring and deeHall - Techniques to enhance recovery rate of prop scars
pening of the disturbed area (F.leuterius 1987). Heavily scarred beds may also be prone to further damage or destruction by severe storms (Fonseca andDeveloping Techniques to Enhance the Recovery Rates of Propeller Scars in Turtlegrass (Thalassia testudinum) Meadows Final Report to USFWSMargaret o. Hall - Techniques to enhance recovery rate of prop scarslines in cover (Preen Ct al. 1995).File Code: F2319-02-F3Recovery rale also varies with the species of seagrass that is scarred. Although the apical meristem controls rhizome elongation, branching, and shoot production in all seagrasses, the rate and pattern of growth varies considerably among speci Hall - Techniques to enhance recovery rate of prop scarses. These growth differences among species substantially influence recovery time from propeller scarring. When a propeller severs a rhizome, the portiHall - Techniques to enhance recovery rate of prop scars
on of the seagrass plant lacking an apical meristem cannot continue to grow until a new one is generated (Dawes et al. 1997). Shoalgrass (Hơlodiile wiDeveloping Techniques to Enhance the Recovery Rates of Propeller Scars in Turtlegrass (Thalassia testudinum) Meadows Final Report to USFWSMargaret o. Hall - Techniques to enhance recovery rate of prop scarshnum) forms new apical meristems slowly (over months or sometimes years), and its rhizomes branch only rarely (Tomlinson 1974). Consequently, propeller scarring in turtlegrass beds usually results in long-term damage. The most heavily damaged seagrass beds in south Florida are dominated by turtlegra Hall - Techniques to enhance recovery rate of prop scarsss (Kenworthy et al. 2000), thus there is a substantial need to develop techniques which can enhance the recovery of propeller scars in Thalassia meadHall - Techniques to enhance recovery rate of prop scars
ows.In response to wide-spread propeller scarring, resource agencies have made numerous attempts to minimize seagrass damage through management actionDeveloping Techniques to Enhance the Recovery Rates of Propeller Scars in Turtlegrass (Thalassia testudinum) Meadows Final Report to USFWSMargaret o. Hall - Techniques to enhance recovery rate of prop scarsopeller scarring and vessel groundings still occur at an alarming rate. Resource agencies must have reliable options for enhancing recovery rates of extensively scarred areas under their management. Preliminary efforts to enhance propeller scar recovery have met with varying degrees of success depen Hall - Techniques to enhance recovery rate of prop scarsdent on planting technique, substrate preparation, and fertilization regime. During the past tlưee years, we have investigated a variety of chemical,Hall - Techniques to enhance recovery rate of prop scars
biological, and physical techniques for enhancing the recovery rates of propeller scars in Thũỉassiũ festudinum meadows simultaneously in two separateDeveloping Techniques to Enhance the Recovery Rates of Propeller Scars in Turtlegrass (Thalassia testudinum) Meadows Final Report to USFWSMargaret o. Hall - Techniques to enhance recovery rate of prop scarsplemental Planting to Accelerate Propeller Scar Recover)' in Florida Turtlegrass (Thalassia testudinum) Meadows.INTRODUCTIONPropeller scarring is a large and chronic problem in Florida seagrass meadows. The habitat value of a seagrass bed is partially derived from its continuous nature. Extensive an Hall - Techniques to enhance recovery rate of prop scarsd repeated scarring breaks up continuous seagrass habitats, reducing the productivity of an area and changing the distribution of fish, shrimp, crabsHall - Techniques to enhance recovery rate of prop scars
and other organisms (Uhrin and Holmquist 2003). Prior research has shown that natural recovery of propeller scars in turtlegrass < Thalassia testudmiiDeveloping Techniques to Enhance the Recovery Rates of Propeller Scars in Turtlegrass (Thalassia testudinum) Meadows Final Report to USFWSMargaret o. Hall - Techniques to enhance recovery rate of prop scarse been removed, but where scar depth remained similar to the adjacent, undamaged meadow. Our goal was to accelerate the natural recolonization of turtlegrass scars via a combination of chemical (nutrient addition) and biological (supplemental planting) techniques.METHODSStudy Sites: Tampa Bay and th Hall - Techniques to enhance recovery rate of prop scarse Florida Keys (Figure 1) were chosen as the study locations because they are among the most extensively propeller-scar damaged areas in Florida. In aHall - Techniques to enhance recovery rate of prop scars
ddition, these locations vary significantly in climatic conditions, as well as in sediment type and nutrient conditions.Experimental Scar Selection. SDeveloping Techniques to Enhance the Recovery Rates of Propeller Scars in Turtlegrass (Thalassia testudinum) Meadows Final Report to USFWSMargaret o. Hall - Techniques to enhance recovery rate of prop scarsme, and light availability). To minimize variation in scar characteristics and enhance our ability to detect differences among experimental treatments, we attempted to locate existing scars for the study based on the following criteria: 1) Scars occur in dense, visually healthy turtlegrass meadows. Hall - Techniques to enhance recovery rate of prop scars2) Scars occur in similar water depths. 3) Scars are approximately 40 m in length (minimum) and 0.35 m in width. 4) Scar depth is equivalent to the deHall - Techniques to enhance recovery rate of prop scars
pth of the adjacent, undamaged meadow. 5) Scars are of recent originFile Code: F2319-O2-FGọi ngay
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