Biology of Posidonia

Gobert, Sylvie; Cambridge, Marion L.; Velimirov, B.; Pergent, Gérard; Lepoint, Gilles; Bouquegneau, Jean-Marie; Dauby, Patrick; Pergent-Martinì, Christine; Walker, Diana

doi:10.1007/978-1-4020-2983-7_17

Cited by 37 publications

(37 citation statements)

References 161 publications

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“…The three-fold higher C org stores in P. oceanica compared to P. australis could be attributed to the higher sediment accumulation rates in P. oceanica meadows (2.1 ± 0.4 mm yr −1 ), enhanced by their vertical rhizomal growth (i.e., orthotropic) compared to the horizontal rhizomal growth (i.e., plagiotropic) in P. australis meadows (0.8 ± 0.4 mm yr −1 ; Table 1; Gobert et al, 2006). In Figure 1, we highlight the differences in the rhizomal growth between the two Posidonia species.…”

Section: Resultsmentioning

confidence: 99%

Location and Associated Carbon Storage of Erosional Escarpments of Seagrass Posidonia Mats

et al. 2016

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Seagrasses of the genus Posidonia can form an irregular seascape due to erosional processes exposing thick walls of organic matter-rich soils. However, little is known about the location and characteristics of these particular formations. Here we provide comprehensive estimates of organic carbon (C org ) storage in Posidonia oceanica and Posidonia australis meadows, while providing insight into their location and mechanisms of formation, and highlighting future research directions. Erosional reef escarpments are restricted to shallow highly productive P. oceanica meadows from the Mediterranean Sea and P. australis meadows from the Indian Ocean, and sustain the existence of C org -rich deposits in surrounding meadows. The thickness of the mat escarpments can reach up to 3 m and their length can vary from few to hundreds of meters. Mechanisms of formation appear to differ among sites, from naturally-induced escarpments by wave action and/or tidal flow to human-induced escarpments by dredging activities. The inter-twined remains of seagrass shoots within the sediment matrix consolidate the sandy substrate and hold the exposed Posidonia mat escarpments together, maintaining a semi-rigid structure. This phenomenon is unusual but of exceptional importance in marine biogeochemical cycles, revealing the largest C org sinks among seagrasses worldwide (ranging from 15 to 176 kg C org m −2 in 2 m-thick mats accumulated at 2-249 g C org m −2 yr −1 over 300-3000 yr).

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Section: Resultsmentioning

confidence: 99%

Location and Associated Carbon Storage of Erosional Escarpments of Seagrass Posidonia Mats

et al. 2016

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“…P. oceanica covers an area in the Mediterranean Sea between 2.5 and 5 million ha (Pasqualini et al 1998). Previous genetic analyses (Waycott & Les 2000) and the fossil record have shown one Australian (P. australis) and one Mediterranean (P. oceanica) species to be genetically distant, which support an early evolutionary separation (Gobert et al 2006). Based on presumed geological history and continental drift, Phillips & Menez (1988) estimated that the Australian P. australis and the Mediterranean P. oceanica diverged during the late Eocene ca.…”

Section: Introductionmentioning

confidence: 90%

“…More recently, morphological information combined with allozymes revealed that P. coriacea and P. robertsoniae within the P. ostenfeldii complex are synonyms (Campey et al 2000) resulting in 7 recognized species in the Australian complexes. Despite the relatively small number of Posidonia species, 3 groups are recognized based on the presence or absence of a primary root in the Australian and Mediterranean species respectively, on the width of their leaf (thicker but stiffer in the P. ostenfeldii complex) and on rhizome features (horizontal/vertical growth) as well as ecological characteristics associated with the 2 Australian groups (P. australis and P. ostenfeldii complexes) (Gobert et al 2006).…”

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

Evolutionary history of the seagrass genus Posidonia

Aires¹,

Marbà²,

Cunha³

et al. 2011

Mar. Ecol. Prog. Ser.

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Seagrasses are the structural species of one of the most important coastal ecosystems worldwide and support high levels of biodiversity and biomass production. Posidonia is one of the most ancient seagrass genera and displays a contrasting disjunct biogeographic pattern. It contains one single species in the Northern Hemisphere, P. oceanica, which is endemic to the Mediterranean Sea, and has up to 8 recognized taxa in the Southern Hemisphere, which in Australia are divided into 2 complexes, P. ostenfeldii and P. australis. A phylogeny based on a nuclear marker (rRNA-ITS) revealed an ancient split between the northern (i.e. Mediterranean) and southern (i.e. Australian) taxa, followed by a separation of the 2 recognized Australian complexes. However, the species belonging to the P. ostenfeldii complex were indistinguishable, suggesting an ecotypic origin or a recent speciation. Therefore, among the 7 morphologically described Australian species only 4 species lineages can be discriminated. The organelle markers nad 7 intron, trnL-F and mat K/trnK intron were not informative for reconstructing the phylogeny of this genus, and the mitochondrial markers exhibited a strikingly slow evolutionary rate relative to other genome regions.KEY WORDS: Posidonia · Phylogeny · Low evolutionary rates · Ancient diversification Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 421: [117][118][119][120][121][122][123][124][125][126][127][128][129][130] 2011 (Den Hartog 1970). Fossils of Posidonia found in Europe and recorded from the Cretaceous to the Miocene have remained apparently almost unchanged over this long evolutionary history (Den Hartog 1970).Based on ecological, vegetative, reproductive and morphological characteristics, 9 species were initially described with a unique fragmented distribution. Posidonia oceanica is endemic to the Mediterranean Sea, whereas the other 8 described species (P. australis, P. sinuosa and P. angustifolia from the P. australis complex and P. coriacea, P. denhartogii, P. kirkmanii, P. ostenfeldii and P. robertsoniae from the P. ostenfeldii complex) are restricted to subtropical and temperate Australian waters (Cambridge & Kuo 1979, Kuo & Cambridge 1984 and are separated by about 17 000 km from their Mediterranean congeneric species. More recently, morphological information combined with allozymes revealed that P. coriacea and P. robertsoniae within the P. ostenfeldii complex are synonyms (Campey et al. 2000) resulting in 7 recognized species in the Australian complexes. Despite the relatively small number of Posidonia species, 3 groups are recognized based on the presence or absence of a primary root in the Australian and Mediterranean species respectively, on the width of their leaf (thicker but stiffer in the P. ostenfeldii complex) and on rhizome features (horizontal/vertical growth) as well as ecological characteristics associated with the 2 Australian groups (P. australis and P. ostenfeldii complexes) (Gobert et al. 2006).Australian...

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“…Furthermore, temperature limits for the growth of living P. oceanica on top of the mat should be taken into consideration as it affects the input of detritus to the mat. P. oceanica can live within a broad temperature range of 9 to 29°C (Gobert et al 2006), but if the ocean temperature increa ses above the 29°C, even just for short periods, plant mortality increases (Marbà & Duarte 2010) and accumulation of detritus could be drastically reduced.…”

Section: Temperature Effects On Mat Decompositionmentioning

confidence: 99%

Temperature effects on decomposition of a Posidonia oceanica mat

Pedersen¹,

Serrano²,

Mateo³

et al. 2011

Aquat. Microb. Ecol.

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Posidonia oceanica mats act as an important carbon (C) sink in the Mediterranean by accumulating roots, rhizomes and leaf sheaths, and allochthonous organic matter over millennia due to low rates of decomposition of organic matter. Thus far, rates of decomposition have only been modeled, whereas few attempts have been made to measure decomposition rates under in situ conditions in P. oceanica mats. We studied decomposition of P. oceanica mats by simulating in situ conditions at different temperatures. Samples from 5 different depths in a 3 m thick vertical profile of a P. oceanica mat were each incubated under anoxic conditions for 7 mo at 5 different temperatures (15, 20, 25, 30, and 35°C). Our measured low mat mineralization rates confirm slow decomposition and support that P. oceanica mats act as important long-term C sinks in the Mediterranean. However, between 15 and 25°C, both C and nitrogen (N) mineralization increased with increasing temperature, and generally declined above 25°C, probably due to unbalanced bacterial growth in the mat. Relatively, N mineralization was stimulated more than CO 2 release (i.e. up to 14.3 and 4.5 times, respectively), suggesting that regeneration of N in P. oceanica mats is enhanced with increasing temperatures up to 25°C. This may affect the nutrient dynamics in this oligotrophic ecosystem. Our data suggest that CO 2 release due to decomposition of the mat is potentially enhanced under a scenario of climate change, thus reducing the C sequestration capacity of the mats during this century. KEY WORDS: Mineralization · Carbon sink · Nitrogen · Seagrass · Mediterranean SeaResale or republication not permitted without written consent of the publisher

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Biology of Posidonia

Cited by 37 publications

References 161 publications

Location and Associated Carbon Storage of Erosional Escarpments of Seagrass Posidonia Mats

Location and Associated Carbon Storage of Erosional Escarpments of Seagrass Posidonia Mats

Evolutionary history of the seagrass genus Posidonia

Temperature effects on decomposition of a Posidonia oceanica mat

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