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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.
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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)
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.
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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)