Current Search:  Seagrasses -- Physiology (x)

View All Items

  • CSV Spreadsheet
(1 - 4 of 4)
effects of the cyanobacterium Lyngbya majuscula and artificial shading on the seagrass Halodule wrightii
Title
The effects of the cyanobacterium Lyngbya majuscula and artificial shading on the seagrass Halodule wrightii.
Creator
Tiling, Kathryn A., Harriet L. Wilkes Honors College
Abstract/Description
Extensive blooms of the marine cyanobacterium Lyngbya majuscula occurred during 2006 in Halodule wrightii seagrass beds. We examined the effects of L. majuscula blooms on seagrass by removal treatments and assessed if this was primarily an effect of shading by conducting artificial shade treatments. We tested the effects of L. majuscula removal and artificial shading on fifty individual 0.25 m2 experimental seagrass plots infested with L. majuscula in a fully crossed, two-way experiment....
Show moreExtensive blooms of the marine cyanobacterium Lyngbya majuscula occurred during 2006 in Halodule wrightii seagrass beds. We examined the effects of L. majuscula blooms on seagrass by removal treatments and assessed if this was primarily an effect of shading by conducting artificial shade treatments. We tested the effects of L. majuscula removal and artificial shading on fifty individual 0.25 m2 experimental seagrass plots infested with L. majuscula in a fully crossed, two-way experiment. Measurements included blade elongation, biomass, and stem density. Blade lengths of H. wrightii were significantly increased by the presence of artificial shading and L. majuscula. L. majuscula removal resulted in increased below ground biomass in shaded plots, suggesting an increase in stores, when possible, for accelerated recovery following a shading event. Adverse L. majuscula effects occurred after declines in bloom biomass indicating that L. majuscula can have a prolonged negative effect on H. wrightii production.
Show less
Date Issued
2007
PURL
http://purl.flvc.org/FAU/11597
Subject Headings
Cyanobacteria, Biological control, Seagrasses, Physiology, Seagrasses, Effect of salt on, Restoration ecology, Halodule wrightii, Morphology
Format
Document (PDF)
Biomonitoring of hypoxia and sulfide stress in three sub-tropical seagrasses
Title
Biomonitoring of hypoxia and sulfide stress in three sub-tropical seagrasses.
Creator
Irwin, Connor., Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
Hypoxia and sulfide exposure, increased using glucose, are considered major environmental stressors in seagrass communities. Quantum efficiency, total soluble protein and catalase activity were quantified to evaluate the applicability of each of these bioindicators to detect environmental stress in three tropical seagrass species, Thalassia testudinum (Banks ex Kèoenig), Halodule wrightii (Ascherson) and Syringodium filiforme (Kuetz). Hypoxia + sulfide treatments significantly decreased the...
Show moreHypoxia and sulfide exposure, increased using glucose, are considered major environmental stressors in seagrass communities. Quantum efficiency, total soluble protein and catalase activity were quantified to evaluate the applicability of each of these bioindicators to detect environmental stress in three tropical seagrass species, Thalassia testudinum (Banks ex Kèoenig), Halodule wrightii (Ascherson) and Syringodium filiforme (Kuetz). Hypoxia + sulfide treatments significantly decreased the quantum efficiency of all three species, but showed no response in protein and catalase activity. Although no treatment effect was found, catalase activity was enhanced in T. testudinum leaves and H. wrightii roots relative to other tissues, while S. filiforme showed no location-specific catalase activity. These results indicate that quantum efficiency is a more sensitive indicator than protein and catalase activity to hypoxia and sulfide stress in seagrasses.
Show less
Date Issued
2010
PURL
http://purl.flvc.org/FAU/2976445
Subject Headings
Plant physiology, Environmental management, Seagrasses, Habitat, Environmental aspects, Sulfites, Physiological effect, Marine ecology
Format
Document (PDF)
Sulfur-35 incorporation in the seagrass Thalassia testudinum under oxic and anoxic conditions
Title
Sulfur-35 incorporation in the seagrass Thalassia testudinum under oxic and anoxic conditions.
Creator
Peters, Jasmine Star., Florida Atlantic University, Koch, Marguerite
Abstract/Description
Currently, there is a great deal of interest in the role of sulfur in the seagrass ecosystems and for sulfide, a known phytotoxin, in particular. This research used a 35S tracer technique to examine sulfur metabolism in the seagrass Thalassia testudinum. The uptake of the 35S radiotracer was documented at similar rates under both oxic and anoxic treatments. The highest total radioactivity was in root and rhizome tissue, as compared to the leaves. 35S translocation from roots to leaves was...
Show moreCurrently, there is a great deal of interest in the role of sulfur in the seagrass ecosystems and for sulfide, a known phytotoxin, in particular. This research used a 35S tracer technique to examine sulfur metabolism in the seagrass Thalassia testudinum. The uptake of the 35S radiotracer was documented at similar rates under both oxic and anoxic treatments. The highest total radioactivity was in root and rhizome tissue, as compared to the leaves. 35S translocation from roots to leaves was found to be more efficient in young versus mature leaves. Total sulfur uptake was estimated and found to be significantly different between root and rhizome tissue under oxic conditions. In the anoxic treatment, 1 mM sulfide may have been a threshold, at which the seagrass showed reduced uptake of 35S into the below-ground tissue. While the plants assisted in the production of sulfide in this experiment, sulfide accumulation may inhibit 35S uptake. This is counter to the idea of increased sulfide intrusion under sediment hypoxia. This study represents the first attempt to use 35S to trace sulfur incorporation into seagrass; further research will be required to understand the complex sulfur biochemistry of these important marine plants using this method.
Show less
Date Issued
2006
PURL
http://purl.flvc.org/fcla/dt/13385
Subject Headings
Seagrasses--Ecology, Sulfates--Physiological effect, Plant morphology, Marine sediments
Format
Document (PDF)
The Role Of Disturbance In The Genotypic And Morphological Diversity Of Halodule Wrightii
Title
The Role Of Disturbance In The Genotypic And Morphological Diversity Of Halodule Wrightii.
Creator
Tiling, Kathryn A., Proffitt, C. Edward, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
Seagrasses are important foundation species in coastal ecosystems. Genetic diversity of seagrasses can influence a number of ecological factors including, but not limited to, disturbance resistance and resilience. Seagrasses in the Indian River Lagoon (IRL), Florida are considered to be highly disturbed due to frequent events, like algal blooms, that impair water quality, reducing available light for seagrass growth. Halodule wrightii is a dominant seagrass throughout the IRL, but its genetic...
Show moreSeagrasses are important foundation species in coastal ecosystems. Genetic diversity of seagrasses can influence a number of ecological factors including, but not limited to, disturbance resistance and resilience. Seagrasses in the Indian River Lagoon (IRL), Florida are considered to be highly disturbed due to frequent events, like algal blooms, that impair water quality, reducing available light for seagrass growth. Halodule wrightii is a dominant seagrass throughout the IRL, but its genetic diversity has only been quantified in a few Gulf of Mexico and Florida Bay populations and little is known about its potential ecological consequences. I quantified the genetic variation of H. wrightii using microsatellite markers in the southern IRL to determine: (i) how disturbance history influenced genetic diversity, (ii) if morphology of clones was, in part, genetically controlled and related to disturbance history, and (iii) if genotypes showed phenotypic plasticity in response to disturbances. In the IRL, H. wrightii populations exhibited moderate genetic diversity that varied with disturbance history. The disturbance history of a population was classified by the variance in the percent occurrence of H. wrightii over a 16-year period. Genotypic richness and clonal diversity of H. wrightii increased with increasing disturbance histories. Other genetic diversity measures (e.g., allelic richness, observed heterozygosity) did not change with disturbance history. These findings suggest that impacts to seagrass coverage over time can change the genotypic composition of populations. When different genotypes of H. wrightii were grown in a common garden, differences in leaf characteristics among genotypes provided evidence that morphological trait variation is, in part, explained by genetic variance. The disturbance history of genotypes did not directly affect morphological traits. However, significant genotype x site (within disturbance history) interactions found greater variation in shoot density and below ground traits of H. wrightii genotypes from sites of intermediate disturbance history. Traits of H. wrightii were shown to be phenotypically plastic. Significant genotype x environment interactions for shoot density and height demonstrated that genotypes responded differently by increasing, decreasing, and not changing sizes in response to light reduction. Genetic diversity of H. wrightii has strong implications for ecological function in coastal communities.
Show less
Date Issued
2016
PURL
http://purl.flvc.org/fau/fd/FA00004661, http://purl.flvc.org/fau/fd/FA00004661
Subject Headings
Indian River (Fla. : Lagoon) -- Enviornmental conditions, Indian River Lagoon National Estuary Program (Fla.), Marine ecology -- Florida -- Indian River (Lagoon), Restoration ecology, Seagrasses -- Florida -- Indian River (Lagoon), Seagrasses -- Physiology
Format
Document (PDF)