The Long-term Effects of Sargassum muticum (Yendo) Fensholt Invasion on Zostera marina L. and its Associated Epibiota
Date
20122012
Author
Subject
Metadata
Show full item recordAbstract
In this thesis I review how Sargassum muticum (Yendo) Fensholt, an invasive alga from Asia, has spread globally due to human activities and describe how this species can affect seagrass ecosystems. Abiotic factors such as nutrient and substratum availability may facilitate the spread of S. muticum into Zostera marina L. meadows, but analyses of seawater nutrients, and sediment particle size and % organic content revealed no significant differences between experimental quadrats in seagrass meadows either with, or without the presence of S. muticum. Phenolic compounds were examined because they form the basis of defensive mechanisms in plants and algae, therefore any change in phenolic content may affect the ability of Z. marina to protect itself from disease, herbivory and invasive species through allelopathic interactions. Results from a four year field study and multiple annual laboratory experiments showed significant reductions (p = 0.034 and p = 0.002, respectively) in the caffeic and tannic acids equivalents content of Z. marina when in the presence of S. muticum. As the abundance of S. muticum increases, other changes in the physiology of Z. marina may occur including variations in growth rates, nutrient partitioning and chlorophyll fluorescence, but data from multiple laboratory experiments illustrated no significant differences in growth. Chlorophyll fluorescence analyses revealed significant differences between treatments with and without S. muticum (p = 0.008), but pairwise comparisons indicated these differences only occurred in 2008 (p < 0.001). Significant differences were also found in nutrient partitioning amongst functional regions of the shoots (p = 0.024), but pairwise comparisons detected these differences between a biomass control treatment (ZZ: Zostera + Zostera) and the ZS (with S. muticum) and ZM (Z. marina on its own at a lower biomass per replicate) treatments (p = 0.013 and p = 0.019, respectively), but not between ZS and ZM. Previous in situ research has found negative effects of S. muticum presence on densities of kelp and other algae. Results from the long-term field study indicated significantly lower mean in situ Z. marina densities within the ZS treatment (p < 0.001). Epibiota found living on the blades of Z. marina provide food for organisms within seagrass ecosystems and also create microhabitats for other species to occupy. Alterations in the abundances of epibiota and microhabitats formed could further modify seagrass ecosystems through shifts in timing of food availability, food preferences and microhabitats created. The long-term field study data revealed significantly lower epibiota abundances within the ZS treatment (p = 0.019), but differences in biomass between treatments were not detected. Changes in the biochemistry, physiology, vegetative physiognomy and epibiota assemblages of Z. marina revealed during experimental manipulations are presented and considered within the context of long-term seagrass survival in light of increasing S. muticum invasion.
Collections
Publisher
Commissioning body
The following license files are associated with this item:
Related items
Showing items related by title, author, creator and subject.
-
Use of a seagrass residency index to apportion commercial fishery landing values and recreation fisheries expenditure to seagrass habitat service
Jackson, EL; Rees, Sian; Wilding, C; Attrill, Martin (WileyUnited States, 2015-06)Where they dominate coastlines, seagrass beds are thought to have a fundamental role in maintaining populations of exploited species. Thus, Mediterranean seagrass beds are afforded protection, yet no attempt to determine ... -
The toxicity of M1 (2-methylthio-4-tert-butylamino-6-amino-s-triazine) to the seagrass Zostera marina (L.) in terms of photosynthetic efficiency and growth
Evans, Timothy Walker (University of Plymouth, 2005)M1 (2-methylthio-4-te/t-butylamino-6-amino-s-triazine) is a more persistent degradation product of Irgarol 1051 which is a booster biocide that causes photosystem II inhibition of target species in the new breed of ... -
An evaluation of Ecological Niche modelling as a predictive management tool to map habitat suitability of seagrasses (Zostera marina) in UK coastal waters
Hinman, Thomas C. (University of Plymouth, 2010)Seagrasses including Zostera marina exist in extensive communities in shallow subtidal zones of UK waters and are therefore subject to intense natural and anthropogenic pressures. As an internationally important species, ...