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Gérard Pergent - One of the best experts on this subject based on the ideXlab platform.
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Is Posidonia oceanica regression a general feature in the Mediterranean Sea
Mediterranean Marine Science, 2013Co-Authors: Marina Bonacorsi, Christine Pergent-martini, N. Breand, Gérard PergentAbstract:Over the last few years, a widespread regression of Posidonia oceanica meadows has been noticed in the Mediterranean Sea. However, the magnitude of this decline is still debated. The objectives of this study are (i) to assess the spatio-temporal evolution of Posidonia oceanica around Cap Corse (Corsica) over time comparing available ancient maps (from 1960) with a new (2011) detailed map realized combining different techniques (aerial photographs, SSS, ROV, scuba diving); (ii) evaluate the reliability of ancient maps; (iii) discuss observed regression of the meadows in relation to human pressure along the 110 km of coast. Thus, the comparison with previous data shows that, apart from sites clearly identified with the actual evolution, there is a relative stability of the surfaces occupied by the seagrass Posidonia oceanica . The recorded differences seem more related to changes in mapping techniques. These results confirm that in areas characterized by a moderate anthropogenic impact, the Posidonia oceanica meadow has no significant regression and that the changes due to the evolution of mapping techniques are not negligible. However, others facts should be taken into account before extrapolating to the Mediterranean Sea (e.g. actually mapped surfaces) and assessing the amplitude of the actual regression.
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Morpho-chronological variations and primary production in Posidonia sea grass from Western Australia
Journal of the Marine Biological Association of the United Kingdom, 2004Co-Authors: Gérard Pergent, Christine Pergent-martini, Catherine Fernandez, Vanina Pasqualini, Diana WalkerAbstract:The occurrence of morpho-chronological variations was demonstrated in three Australian species of phanerogams, Posidonia australis, Posidonia coriacea and Posidonia sinuosa, which are found living around Rottnest Island (Western Australia). Three chronological parameters were identi¢ed: the thickness of dead sheaths, the internodal distance and the regular presence of £oral stalk remains. The foliar primary production for these three species, as estimated using the lepidochronology method, is very high since values of 1374, 1811and 678 mg dw shoot 71 y 71 were recorded, respectively. Rhizome production values range from 70.6 and 376.7 mg dw shoot 71 y 71 for Posidonia coriacea and Posidonia australis respectively. The results obtained are very encouraging and con¢rm that these morpho-chronological variations are particularly well developed for the genus Posidonia.
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Distribution and dynamics of Posidonia oceanica beds along the Albères coastline
Comptes Rendus De L Academie Des Sciences Serie Iii-sciences De La Vie-life Sciences, 2000Co-Authors: Laurent Ballesta, Gérard Pergent, Vanina Pasqualini, Christine Pergent-martiniAbstract:The location and dynamics of Posidonia oceanica beds were studied in the marine natural reserve of Cerbere–Banyuls-sur-Mer (eastern Pyrenees, France), through the mapping of bottom assemblages (transects and image processing) and the monitoring of fixed markers installed at the Posidonia oceanica lower limit. The surface area occupied by continuous beds is relatively limited and localized, whereas the presence of important areas of dead ‘matte’ would seem to indicate that bottom cover by Posidonia oceanica was more extensive in the past. Although the limited extension of the seagrass beds seems to be linked to both a high level of turbidity and severe hydrodynamic conditions, it is hypothesized that the regressions observed are due to lack of sediment.
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Preliminary data on the impact of fish farming facilities on Posidonia oceanica meadows in the Mediterranean
Oceanologica Acta, 2000Co-Authors: Gérard Pergent, Christine Pergent-martini, Stéphane Mendez, Vanina PasqualiniAbstract:While the extension of aquaculture along the coasts of the Mediterranean islands is today an economic priority, no data is available on the impact of these facilities on the littoral environment in general, and in particular on the Posidonia oceanica meadows that are responsible for the richness and diversity of these biotopes. The impact of fish farming facilities in the marine littoral environment is assessed at three Mediterranean sites in Corsica and Sardinia. Various parameters are considered: (i) the amount of light available, (ii) the nature of the sediment, and (iii) the vitality of the Posidonia oceanica beds. The findings confirm the impact of the aquaculture facilities within the water column (increase in turbidity, enrichment of the sediment in organic matter and nutrients), and it would appear that the Posidonia oceanica beds also undergo significant alterations. The decline in density of the meadows in the area influenced by aquaculture farming and their total disappearance beneath the facilities is particularly disturbing, even if the areas affected are not very extensive, at least for the smaller farms (a few hundred square metres), and if certain beneficial effects may be recorded (increase in benthic primary production). Because of its ability to record environmental alterations caused by these facilities (light, nutrients, trace metals), the Posidonia oceanica meadow is a good bioindicator for use in monitoring studies.
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Nutrient impact on Posidonia oceanica seagrass meadows : preliminary data
Marine life, 1995Co-Authors: Christine Pergent-martini, V. Rico-raimondino, Gérard PergentAbstract:Depuis de nombreuses annees les herbiers a Posidonia oceanica presentent des regressions massives a proximite des grands centres urbains et industriels. L'origine de ces regressions a souvent ete imputee a la turbidite ou a l'action de polluants chimiques (hydrocarbures, PCB, metaux lourds...). En revanche, l'action des nutriments a rarement ete prise en compte, et ce, malgre l'augmentation generale de leur concentration dans le milieu. Aussi afin d'estimer l'impact des nutriments sur l'herbier a Posidonia oceanica, des mesures de densite d'herbier et de concentrations du sediment en nutriments sont effectuees dans une station anthropisee (Plateau des Chevres, Marseille). Il semble qu'il y a une relation entre la repartition des faisceaux de Posidonia oceanica (par ex., patchiness) et les teneurs de certains nutriments (par ex., Ammonium, Nitrites). En complement des essais de fertilisations artificielles sont realises dans un secteur oligotrophe (Baie de Calvi - Corse) de maniere a rechercher l'impact eventuel d'un apport massif de fertilisants (N, P, K) sur Posidonia oceanica. Ces ajouts se sont traduits par un effet negatif sur la croissance de Posidonia oceanica pouvant meme entrainer la mort des faisceaux foliaires. Un phenomene de competition plante-epiphyte semble etre a l'origine de cette mortalite.
Marion L. Cambridge - One of the best experts on this subject based on the ideXlab platform.
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First report of hybridization in the seagrass genus Posidonia (Posidoniaceae)
Aquatic Botany, 2019Co-Authors: Elizabeth A. Sinclair, Marion L. Cambridge, Gary A. KendrickAbstract:Abstract Hybridization is common among plants and has been crucial in the evolution of many aquatic plant groups. However, hybrid individuals are often difficult to identify, particularly in the marine environment. We aim to confirm a hybrid origin between two seagrass species for a morphologically-intermediate plant observed in shallow subtidal environments near Perth, Western Australia. Both morphological measures and DNA markers demonstrated a clear case for hybridization among two sympatric Posidonia species from different species complexes: Posidonia australis and P. coriacea. All five samples with the intermediate morphology had the same multilocus genotype (MLG), providing evidence that it resulted from a single hybridization event, followed by local clonal (rhizome) expansion. This result highlights weak reproductive barriers within the genus Posidonia, a trait common among other seagrass genera with sympatric ranges, apparently overlapping morphologies and low phylogenetic divergence.
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Two new species of seagrasses from Australia, Posidonia sinuosa and P. angustifolia (Posidoniaceae)
Aquatic Botany, 2003Co-Authors: Marion L. CambridgeAbstract:Two new species of seagrass, Posidonia sinuosa and Posidonia angustifolia, from southern Australia, are described. These species are sympatric with the broad leaved Posidonia australis Hook. f., under which name they were previously known as “narrow leaved” forms. Morphological, anatomical and ecological data are presented as evidence for the separation of the species. The principal differentiating characters are the shape of the epidermal cells, the position of fibre cells in the leaf and leaf sheath, and the presence around the rhizome of straw-like fibres, derived from the disintegrating leaf sheaths. The species also differ in their habitat requirements, growth patterns and depth distribution.
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Seagrasses of south-western Australia with special reference to the ecology of Posidonia australis Hook f. in a polluted environment
Aquatic Botany, 2003Co-Authors: Marion L. CambridgeAbstract:Cambridge, M.L., 1975. Seagrasses of south-western Australia with special reference to the ecology of Posidonia australis Hook f. in a polluted environment. Aquat. Bot., 1:149--161 New ecological data are given for the nine species of seagrasses of south-western Australia, with special reference to Posidonia australis in Cockburn Sound, a polluted marine embayment.
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Morphology, anatomy and histochemistry of the Australian seagrasses of the genus Posidonia König (Posidoniaceae) III. Posidonia sinuosa Cambridge & Kuo
Aquatic Botany, 2003Co-Authors: Marion L. CambridgeAbstract:Abstract The vegetative structures of Posidonia sinuosa Cambridge & Kuo have been studied and are compared to those of Posidonia australis Hook. f. and, where possible, the ecological significance of structures is considered. Each shoot of P. sinuosa bears 1–2 leaves which grow more slowly than those of P. australis. The leaf cuticle has a uniformly low electron density and is not porous in appearance. The elongated leaf blade epidermal cells have a rugulose surface and sinuose outline, but have no cell wall ingrowths. Microfibrillar arrangement, in the inner portion of the distal wall and the distal portion of the radial wall in leaf epidermal cells, appears to be a source of mechanical weakness resulting in longitudinal splitting of the leaf blades when they are subjected to the stress of strong wave action, so that the species is usually restricted to calmer habitats. Only a few fibre bundles are present in the parenchyma tissues of leaf sheaths, so that P. sinuosa does not form marine fibre deposits. Anatomy and ultrastructure of rhizome and root in both P. sinuosa and P. australis are similar. Posidonia sinuosa dominates habitats with limited sand influx which appears to be related to its capacity for limited rhizome growth.
Charlesfrancois Boudouresque - One of the best experts on this subject based on the ideXlab platform.
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primary production stocks and fluxes in the mediterranean seagrass Posidonia oceanica
Marine Ecology Progress Series, 1994Co-Authors: Gérard Pergent, Javier Romero, Christine Pergentmartini, Miguel Angel Mateo, Charlesfrancois BoudouresqueAbstract:Primary production in a Posidonia oceanica seagrass meadow (blades, sheaths and rhizomes) was estimated at 3 sites in Lacco Ameno Bay (Ischia. Italy). Foliar primary production ranged from 51 to 142 g dry wt m2 yr-l for sheaths and 167 to 530 g dry wt m2 yr-' for blades. Rhizome production ranged from 20 to 42 g dry wt m2 yr-'. The largest part of primary production was degraded in sit11 In the litter (42 % l ; the remainder was either exported to other ecosystems (29%) or buried in the rnatte (29%). The loss of matter due to burial of sheaths and rhizomes in the matte, a phenonlenon that is unique to Posidonja oceanica meadows, is considerable.
Antonio Sanchezamat - One of the best experts on this subject based on the ideXlab platform.
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marinomonas alcarazii sp nov m rhizomae sp nov m foliarum sp nov m posidonica sp nov and m aquiplantarum sp nov isolated from the microbiota of the seagrass Posidonia oceanica
International Journal of Systematic and Evolutionary Microbiology, 2011Co-Authors: Patricia Lucaselio, Ester Marconoales, Elena Espinosa, Monica Ordax, Maria M Lopez, Neus Garciasbonet, Nuria Marba, Carlos M Duarte, Antonio SanchezamatAbstract:Five novel Gram-reaction-negative aerobic marine bacterial strains with DNA G+C contents <50 mol% were isolated from the seagrass Posidonia oceanica. 16S rRNA sequence analysis indicated that they belonged to the genus Marinomonas. Major fatty acid compositions, comprising C10 : 0 3-OH, C16 : 0, C16 : 1ω7c and C18 : 1ω7c, supported the affiliation of these strains to the genus Marinomonas. Strains IVIA-Po-14bT, IVIA-Po-145T and IVIA-Po-155T were closely related to Marinomonas pontica 46-16T, according to phylogenetic analysis. However, DNA–DNA hybridization values <35 % among these strains revealed that they represented different species. Further differences in the phenotypes and minor fatty acid compositions were also found among the strains. Another two strains, designated IVIA-Po-181T and IVIA-Po-159T, were found to be closely related to M. dokdonensis DSW10-10T but DNA–DNA relatedness levels <40 % in pairwise comparisons, as well as some additional differences in phenotypes and fatty acid compositions supported the creation of two novel species. Accordingly, strains IVIA-Po-14bT ( = CECT 7730T = NCIMB 14671T), IVIA-Po-145T ( = CECT 7377T = NCIMB 14431T), IVIA-Po-155T ( = CECT 7731T = NCIMB 14672T), IVIA-Po-181T ( = CECT 7376T = NCIMB 14433T) and IVIA-Po-159T ( = CECT 7732T = NCIMB 14673T) represent novel species, for which the names Marinomonas alcarazii sp. nov., Marinomonas rhizomae sp. nov., Marinomonas foliarum sp. nov., Marinomonas posidonica sp. nov. and Marinomonas aquiplantarum sp. nov. are proposed, respectively.
Carlos M Duarte - One of the best experts on this subject based on the ideXlab platform.
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Posidonia oceanica changes in the Mediterranean sea
2013Co-Authors: Nuria Marba, Elena Díaz-almela, Carlos M DuarteAbstract:Methodology: We compiled available data published in peer-review articles and grey literature reports until year 2009 as well as our own unpublished data. We searched for data with the engine ISI web of Knowledge, using the keywords Posidonia oceanica AND (regression OR decline OR progression OR recovery OR status OR cartography OR limits OR cover OR density OR biomass OR dynamics), and conducting a back search of cited papers. More information about the methodology to be found at: Calleja, M.L., N. Marba, C.M. Duarte (2007). The relationship between seagrass (Posidonia oceanica) decline and sulfide porewater concentration in carbonate sediments. Estuarine coastal and shelf science 73: 583-588; Waycott M, CM. Duarte, T.J. B. Carruthers, R.J. Orth, W.C. Dennison, S. Olyarnik, A. Calladine, J.W. Fourqurean, K.L. Heck, Jr, A.R.ll Hughes, G A. Kendrick, W. J Kenworthy, F T. Short, S L. Williams (2009). Accelerating loss of seagrasses across the globe threatens coastal ecosystems. Proceedings of the National Academy of Science USA 106: 12377–12381; Moreno, D., P. A. Aguilera, H. Castro (2001). Assessment of the conservation status of seagrass (Posidonia oceanica) meadows: implications for monitoring strategy and the decision-making process. Biological Conservation 102: 325-332.
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marinomonas alcarazii sp nov m rhizomae sp nov m foliarum sp nov m posidonica sp nov and m aquiplantarum sp nov isolated from the microbiota of the seagrass Posidonia oceanica
International Journal of Systematic and Evolutionary Microbiology, 2011Co-Authors: Patricia Lucaselio, Ester Marconoales, Elena Espinosa, Monica Ordax, Maria M Lopez, Neus Garciasbonet, Nuria Marba, Carlos M Duarte, Antonio SanchezamatAbstract:Five novel Gram-reaction-negative aerobic marine bacterial strains with DNA G+C contents <50 mol% were isolated from the seagrass Posidonia oceanica. 16S rRNA sequence analysis indicated that they belonged to the genus Marinomonas. Major fatty acid compositions, comprising C10 : 0 3-OH, C16 : 0, C16 : 1ω7c and C18 : 1ω7c, supported the affiliation of these strains to the genus Marinomonas. Strains IVIA-Po-14bT, IVIA-Po-145T and IVIA-Po-155T were closely related to Marinomonas pontica 46-16T, according to phylogenetic analysis. However, DNA–DNA hybridization values <35 % among these strains revealed that they represented different species. Further differences in the phenotypes and minor fatty acid compositions were also found among the strains. Another two strains, designated IVIA-Po-181T and IVIA-Po-159T, were found to be closely related to M. dokdonensis DSW10-10T but DNA–DNA relatedness levels <40 % in pairwise comparisons, as well as some additional differences in phenotypes and fatty acid compositions supported the creation of two novel species. Accordingly, strains IVIA-Po-14bT ( = CECT 7730T = NCIMB 14671T), IVIA-Po-145T ( = CECT 7377T = NCIMB 14431T), IVIA-Po-155T ( = CECT 7731T = NCIMB 14672T), IVIA-Po-181T ( = CECT 7376T = NCIMB 14433T) and IVIA-Po-159T ( = CECT 7732T = NCIMB 14673T) represent novel species, for which the names Marinomonas alcarazii sp. nov., Marinomonas rhizomae sp. nov., Marinomonas foliarum sp. nov., Marinomonas posidonica sp. nov. and Marinomonas aquiplantarum sp. nov. are proposed, respectively.
