Quantifying the dispersal potential of seagrass vegetative fragments: A comparison of multiple subtropical species

Weatherall, Emily; Jackson, Emma L.; Hendry, Rebecca; Campbell, Marnie L.

doi:10.1016/j.ecss.2015.11.026

Cited by 28 publications

(23 citation statements)

References 31 publications

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“…vegetative fragments, fruits and plant fragments with attached fruits and seeds) (Berkovi c et al, 2014). Buoyancy and survival times (although not necessarily leading to successful establishment) for seagrass propagules may be as long as 85 days in temperate species (Thomson et al, 2014), but vary for subtropical species with 0.5 days for H. decipiens, 4.5 days for H. ovalis and 21 days for Z. muelleri (Weatherall et al, 2016). The maximum dispersal distances recorded in the literature are generally less than 100 km, except during extreme weather events when dispersal has been recorded over distances of up to 400 km (Lacap et al, 2002).…”

Section: Coral Reefsmentioning

confidence: 99%

Spatial patterns of seagrass dispersal and settlement

Grech

Wolter

Coles

et al. 2016

Diversity and Distributions

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Aim The movement of propagules among plant populations affects their ability to replenish and recover after a disturbance. Quantitative data on recovery strategies, including the effectiveness of population connectivity, are often lacking at broad spatial and temporal scales. We use numerical modelling to predict seagrass propagule dispersal and settlement to provide an approach for circumstances where direct, or even indirect, measures of population dynamics are difficult to establish. Location Great Barrier Reef, Australia. Methods We used the finite‐element Second‐generation Louvain‐la‐Neuve Ice‐ocean Model (SLIM) to resolve the hydrodynamics of the central Great Barrier Reef and to simulate the dispersal of seagrass. We predicted dispersal and settlement patterns by releasing 10.6 million passive particles representing seagrass propagules at known sites of seagrass presence. We considered two fractions when modelling seagrass dispersal: floating and suspended propagules. Both fractions were modelled using 34 simulations run for a maximum of 8 weeks during the peak seagrass reproductive period, capturing variability in winds, tides and currents. Results The ‘virtual’ seagrass propagules moved on average between 30 and 60 km, but distances of over 900 km also occurred. Most particle movement was to the north‐west. The season (month) of release and source locations of the particles correlated with their dispersal distance, particularly for particles released offshore, with the complex coastal topography impeding movements close to the coast. The replenishment and recovery potential of the northernmost meadows was influenced by southern meadows. Protected north‐facing bays were less likely to receive particles. Main conclusions Our approach advances the conservation and management of marine biodiversity by predicting a key component of ecosystem resilience at a spatial scale that informs marine planning. We show a complex interaction among time, wind, water movement and topography that can guide a management response to improving replenishment and recovery after disturbance events.

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Section: Coral Reefsmentioning

confidence: 99%

Spatial patterns of seagrass dispersal and settlement

Grech

Wolter

Coles

et al. 2016

Diversity and Distributions

View full text Add to dashboard Cite

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“…The study of the movement ecology determining how seagrasses disperse is critical to understanding the exchange of genetic material, and their persistence in changing environments ( McMahon et al, 2014 ; Weatherall et al, 2016 ). The dispersal of seagrass propagules fundamentally affects the genetic structure and diversity of metapopulations ( Kendrick et al, 2012 ), with larger dispersal ranges creating more opportunities for genetic mixing, leading to greater diversity ( Hamrick and Godt, 1996 ).…”

Section: Introductionmentioning

confidence: 99%

“…Abiotic factors, such as wave and current energy, substrate type or water column nutrients, that interact with these traits are also potentially important. A number of preliminary studies have been conducted on several species to elucidate how plant traits and environmental factors (e.g., plant morphometrics, source of fragment, season of fragment production) and their interactions affects the success at different stages (see Ewanchuk and Williams, 1996 ; Hall et al, 2006 ; Berković et al, 2014 ; Weatherall et al, 2016 ), and therefore contribute to overall connectivity of seagrass meadows via the production and transport of their vegetative fragments. However, it is patently clear from the paucity of the scientific literature that there are knowledge gaps on the processes controlling settlement, establishment, and dislodgement of seagrass vegetative fragments, which are key for resolving whether vegetative fragments are a viable conduit for establishment in new areas, and the mechanism by which this can happen.…”

Section: Introductionmentioning

confidence: 99%

Unlikely Nomads: Settlement, Establishment, and Dislodgement Processes of Vegetative Seagrass Fragments

et al. 2018

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The dispersal of seagrasses is important to promoting the resilience and long-term survival of populations. Most of the research on long-distance dispersal to date has focused on sexual propagules while the dispersal of vegetative fragments has been largely overlooked, despite the important role this mechanism might play. In this study, we proposed a conceptual model that categorizes vegetative fragment dispersal into seven fundamental steps: i.e., (i) fragment formation, (ii) transport, (iii) decay, (iv) substrate contact, (v) settlement, (vi) establishment, and (vii) dislodgement. We present two experiments focusing on the final steps of the model from substrate contact to dislodgement in four tropical seagrass species (Cymodocea rotundata, Halophila ovalis, Halodule uninervis, and Thalassia hemprichii), which are critical for dispersed vegetative fragments to colonize new areas. We first conducted a mesocosm experiment to investigate the effect of fragment age and species on settlement (i.e., remains on the substrate in a rising tide) and subsequently establishment (i.e., rooting in substrate) rates. To determine dislodgement resistance of settled fragments, we also subjected fragments under different burial treatments to wave and currents in a flume. We found that both initial settlement and subsequent establishment rates increased with fragment age. H. ovalis was the only species that successfully established within the study period. After settlement, dislodgement resistance depended primarily on burial conditions. Smaller species H. ovalis and H. uninervis were also able to settle more successfully, and withstand higher bed shear stress before being dislodged, compared to the larger species T. hemprichii and C. rotundata. However, the ordinal logistic regressions did not reveal relationships between the tested plant morphometrics and the energy needed for dislodgement (with the exception of C. rotundata), indicating that there are potentially some untested species-specific traits that enable certain species to withstand dislodgement better. We discuss the implication our findings have on the dispersal potential for different species and the conservation of seagrasses. This study represents the first effort toward generating parameters for a bio-physical model to predict vegetative fragment dispersal.

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“…Asch. (Weatherall et al, 2016). Gladstone Harbour is subtropical and reflects a transition zone between temperate and tropical species.…”

Section: Methodsmentioning

confidence: 99%

Niche partitioning of intertidal seagrasses: evidence of the influence of substrate temperature

et al. 2017

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The influence of soil temperature on rhizome depths of four intertidal seagrass species was investigated in central Queensland, Australia. We postulated that certain intertidal seagrass species are soil temperature-sensitive and vertically stratify rhizome depths. Below-ground vertical stratification of intertidal seagrass rhizome depths was analysed based upon microclimate (soil temperature) and microhabitat (soil type). Soil temperature profiles exhibited heat transfer from surface layers to depth that varied by microhabitat, with vertical stratification of rhizome depths between species. Halodule uninervis rhizomes maintain a narrow median soil temperature envelope; compensating for high surface temperatures by occupying deeper, cooler soil substrates. Halophila decipiens, Halophila ovalis and Zostera muelleri rhizomes are shallow-rooted and exposed to fluctuating temperatures, with broader median temperature envelopes. Halodule uninervis appears to be a niche specialist, with the two Halophila species considered as generalist niche usage species. The implications of niche use based upon soil temperature profiles and rhizome rooting depths are discussed in the context of species' thermal tolerances and below-ground biomass O demand associated with respiration and maintenance of oxic microshields. This preliminary evidence suggests that soil temperature interaction with rhizome rooting depths may be a factor that influences the distribution of intertidal seagrasses.

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Quantifying the dispersal potential of seagrass vegetative fragments: A comparison of multiple subtropical species

Cited by 28 publications

References 31 publications

Spatial patterns of seagrass dispersal and settlement

Spatial patterns of seagrass dispersal and settlement

Unlikely Nomads: Settlement, Establishment, and Dislodgement Processes of Vegetative Seagrass Fragments

Niche partitioning of intertidal seagrasses: evidence of the influence of substrate temperature

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