Rhizome elongation and seagrass clonal growth

Marbà, Núria; Duarte, Carlos M.

doi:10.3354/meps174269

Cited by 350 publications

(268 citation statements)

References 21 publications

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“…The vertical rhizome elongation of Thalassia hemprichii shoots (2.7 cm year -1 ) at Lizard Island was similar to estimates from other studies (3 cm year -1 ; Vermaat et al 1995, Marbà andDuarte 1998). The rate of horizontal rhizome elongation of T. hemprichii (33.1 cm year -1 ) was within the range of estimates reported in the literature (mean 54, range 21-88 cm year -1 ; Marbà and Duarte 1998).…”

Section: Rhizome Elongationsupporting

confidence: 87%

Spatial and temporal variability of seagrass at Lizard Island, Great Barrier Reef

Saunders¹,

Bayraktarov

Roelfsema

et al. 2015

Botanica Marina

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Increasing threats to natural ecosystems from local and global stressors are reinforcing the need for baseline data on the distribution and abundance of organisms. We quantified spatial and/or temporal patterns of seagrass distribution, shoot density, leaf area index, biomass, productivity, and sediment carbon content in shallow water (0-5 m) at Lizard Island, Great Barrier Reef, Australia, in field surveys conducted in December 2011 and October 2012. Seagrass meadows were mapped using satellite imagery and field validation. A total of 18.3 ha of seagrass, composed primarily of Thalassia hemprichii and Halodule uninervis, was mapped in shallow water. This was 46% less than the area of seagrass in the same region reported in 1995, although variations in mapping methods may have influenced the magnitude of change detected. There was inter-annual variability in shoot density and length, with values for both higher in 2011 than in 2012.Seagrass properties and sediment carbon content were representative of shallow-water seagrass meadows on a mid-shelf Great Barrier Reef island. The data can be used to evaluate change, to parameterize models of the impact of anthropogenic or environmental variability on seagrass distribution and abundance, and to assess the success of management actions.

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Section: Rhizome Elongationsupporting

confidence: 87%

Spatial and temporal variability of seagrass at Lizard Island, Great Barrier Reef

Saunders¹,

Bayraktarov

Roelfsema

et al. 2015

Botanica Marina

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“…These points highlight an increased dominance of large MLLs. The large MLLs varied in size, reaching at least 19 m in two quadrats (Table 1), and revealed the persistence of a stable core within the seagrass meadows, implanted for several years or decades, as horizontal rhizome elongation rate for Z. marina is estimated between 22 and 31 cm per year (Marba and Duarte, 1998). In addition, genets that 0.14***…”

Section: Discussionmentioning

confidence: 96%

Scaling of processes shaping the clonal dynamics and genetic mosaic of seagrasses through temporal genetic monitoring

et al. 2013

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Theoretically, the dynamics of clonal and genetic diversities of clonal plant populations are strongly influenced by the competition among clones and rate of seedling recruitment, but little empirical assessment has been made of such dynamics through temporal genetic surveys. We aimed to quantify 3 years of evolution in the clonal and genetic composition of Zostera marina meadows, comparing parameters describing clonal architecture and genetic diversity at nine microsatellite markers. Variations in clonal structure revealed a decrease in the evenness of ramet distribution among genets. This illustrates the increasing dominance of some clonal lineages (multilocus lineages, MLLs) in populations. Despite the persistence of these MLLs over time, genetic differentiation was much stronger in time than in space, at the local scale. Contrastingly with the short-term evolution of clonal architecture, the patterns of genetic structure and genetic diversity sensu stricto (that is, heterozygosity and allelic richness) were stable in time. These results suggest the coexistence of (i) a fine grained (at the scale of a 20 Â 30 m quadrat) stable core of persistent genets originating from an initial seedling recruitment and developing spatial dominance through clonal elongation; and (ii) a local (at the scale of the meadow) pool of transient genets subjected to annual turnover. This simultaneous occurrence of initial and repeated recruitment strategies highlights the different spatial scales at which distinct evolutionary drivers and mating systems (clonal competition, clonal growth, propagule dispersal and so on) operate to shape the dynamics of populations and the evolution of polymorphism in space and time. Keywords: clonality; seagrass; spatio-temporal genetic structure; Zostera marina INTRODUCTION Clonality is a life history trait widely distributed among taxa and habitats, particularly in photosynthetic organisms. Partially clonal organisms are characterized by a mixed system allowing the combination of two reproductive strategies: the production of new genetically identical modules through vegetative growth or fragmentation and the production of new genetic individuals through sexual recombination. As a consequence, their population dynamics and evolutionary trajectories are profoundly affected by their rate and mode of clonal reproduction. Populations of clonal plants are composed of genetic individuals, or genets occupying space and dispersing locally through the production of modular shoots, or ramets (Harper, 1977). As genets are able to persist through time and space, the composition and evolution of populations of clonal plants is largely affected by the level of intraspecific competition (Eriksson, 1989(Eriksson, , 1993Pan and Price, 2001;Travis and Hester, 2005).Depending on the turnover of genets and intensity of inter-genet competition for space, two extreme recruitment strategies have been defined (Eriksson, 1993): (i) the 'Initial Seedling Recruitment' (ISR) strategy, characterizing populations originating fro...

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“…and the taxonomically difficult to separate Zostera spp. are pioneer species of smaller size and rapid growth rates (Birch and Birch, 1984;Marbá and Duarte, 1998).…”

Section: Seagrass Speciesmentioning

confidence: 99%

A comparison of the impact of ‘seagrass-friendly’ boat mooring systems on Posidonia australis

Demers

Davis

Knott³

2013

Marine Environmental Research

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Permanent boat moorings have contributed to the decline of seagrasses worldwide, prompting the development of 'seagrass-friendly' moorings. We contrasted seagrass cover and density (predominantly Posidonia australis) in the vicinity of three mooring types and nearby reference areas lacking moorings in Jervis Bay, Australia. We examined two types of 'seagrass-friendly' mooring and a conventional 'swing' mooring. 'Swing' moorings produced significant seagrass scour, denuding patches of ∼9 m radius. Seagrassfriendly 'cyclone' moorings produced extensive denuded patches (average radius of ∼18 m). Seagrass-friendly 'screw' moorings, conversely, had similar seagrass cover to nearby reference areas. Our findings reinforce previous work highlighting the negative effects of 'swing' and 'cyclone' moorings. In contrast, the previously unstudied 'screw' moorings were highly effective. We conclude that regular maintenance of moorings and the monitoring of surrounding seagrass are required to ensure that 'seagrass-friendly' moorings are operating effectively. This is important, as following damage Posidonia will take many decades to recover. AbstractPermanent boat moorings have contributed to the decline of seagrasses worldwide, prompting the development of 'seagrass-friendly' moorings. We contrasted seagrass cover and density (predominantly Posidonia australis) in the vicinity of three mooring types and nearby reference areas lacking moorings in Jervis Bay, Australia. We examined two types of 'seagrass-friendly' mooring and a conventional 'swing' mooring. 'Swing' moorings produced significant seagrass scour, denuding patches of ~9 m radius. Seagrass-friendly 'cyclone' moorings produced extensive denuded patches (average radius of ~18 m). Seagrass-friendly 'screw' moorings, conversely, had similar seagrass cover to nearby reference areas. Our findings reinforce previous work highlighting the negative effects of 'swing' and 'cyclone' moorings. In contrast, the previously unstudied 'screw' moorings were highly effective. We conclude that regular maintenance of moorings and the monitoring of surrounding seagrass are required to ensure that 'seagrass-friendly' moorings are operating effectively. This is important, as following damage Posidonia will take many decades to recover.

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Rhizome elongation and seagrass clonal growth

Cited by 350 publications

References 21 publications

Spatial and temporal variability of seagrass at Lizard Island, Great Barrier Reef

Spatial and temporal variability of seagrass at Lizard Island, Great Barrier Reef

Scaling of processes shaping the clonal dynamics and genetic mosaic of seagrasses through temporal genetic monitoring

A comparison of the impact of ‘seagrass-friendly’ boat mooring systems on Posidonia australis

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