Deterioration of Sediment Quality in Seagrass Meadows (Posidonia oceanica) Invaded by Macroalgae (Caulerpa sp.)

2009 ◽  
Vol 32 (3) ◽  
pp. 456-466 ◽  
Author(s):  
Marianne Holmer ◽  
Núria Marbà ◽  
Morgane Lamote ◽  
Carlos M. Duarte
Keyword(s):  
Sediment Quality ◽  
Posidonia Oceanica ◽  
Seagrass Meadows

scholarly journals Posidonia oceanica as a Source of Chromophoric Dissolved Organic Matter for the Oligotrophic NW Mediterranean Coast

2020 ◽  
Vol 8 (11) ◽  
pp. 911
Author(s):  
Francesca Iuculano ◽  
Carlos M. Duarte ◽  
Jaime Otero ◽  
Xosé Antón Álvarez-Salgado ◽  
Susana Agustí
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Rocky Shore ◽  
Posidonia Oceanica ◽  
Mediterranean Coast ◽  
Balearic Islands ◽  
Chromophoric Dissolved Organic Matter ◽  
Absorption Increase ◽  
Seagrass Meadows ◽  
Nw Mediterranean

Posidonia oceanica is a well-recognized source of dissolved organic matter (DOM) derived from exudation and leaching of seagrass leaves, but little is known about its impact on the chromophoric fraction of DOM (CDOM). In this study, we monitored for two years the optical properties of CDOM in two contrasting sites in the Mallorca Coast (Balearic Islands). One site was a rocky shore free of seagrass meadows, and the second site was characterized by the accumulation of non-living seagrass material in the form of banquettes. On average, the integrated color over the 250–600 nm range was almost 6-fold higher in the beach compared with the rocky shore. Furthermore, the shapes of the CDOM spectra in the two sites were also different. A short incubation experiment suggested that the spectral differences were due to leaching from P. oceanica leaf decomposition. Furthermore, occasionally the spectra of P. oceanica was distorted by a marked absorption increase at wavelength < 265 nm, presumably related to the release of hydrogen sulfide (HS−) associated with the anaerobic decomposition of seagrass leaves within the banquettes. Our results provide the first evidence that P. oceanica is a source of CDOM to the surrounding waters.

scholarly journals Trait gradients inform predictions of seagrass meadows changes to future warming

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Arianna Pansini ◽  
Gabriella La Manna ◽  
Federico Pinna ◽  
Patrizia Stipcich ◽  
Giulia Ceccherelli
Keyword(s):  
Global Warming ◽  
Posidonia Oceanica ◽  
Shoot Density ◽  
Western Mediterranean ◽  
Seagrass Meadows ◽  
Western Mediterranean Sea ◽  
Seagrass Ecosystem ◽  
Rhizome Biomass ◽  
And Function ◽  
Time Substitution

AbstractComparing populations across temperature gradients can inform how global warming will impact the structure and function of ecosystems. Shoot density, morphometry and productivity of the seagrass Posidonia oceanica to temperature variation was quantified at eight locations in Sardinia (western Mediterranean Sea) along a natural sea surface temperature (SST) gradient. The locations are spanned for a narrow range of latitude (1.5°), allowing the minimization of the effect of eventual photoperiod variability. Mean SST predicted P. oceanica meadow structure, with increased temperature correlated with higher shoot density, but lower leaf and rhizome width, and rhizome biomass. Chlorophyll a (Chl-a) strongly impacted seagrass traits independent of SST. Disentangling the effects of SST and Chl-a on seagrass meadow shoot density revealed that they work independently, but in the same direction with potential synergism. Space-for-time substitution predicts that global warming will trigger denser seagrass meadows with slender shoots, fewer leaves, and strongly impact seagrass ecosystem. Future investigations should evaluate if global warming will erode the ecosystem services provided by seagrass meadows.

scholarly journals Feeding preferences of amphipod crustaceans Ampithoe ramondi and Gammarella fucicola for Posidonia oceanica seeds and leaves

2019 ◽  
Vol 83 (4) ◽  
pp. 349
Author(s):  
Inés Castejón-Silvo ◽  
Damià Jaume ◽  
Jorge Terrados
Keyword(s):  
Direct Evidence ◽  
Paracentrotus Lividus ◽  
Posidonia Oceanica ◽  
Feeding Preferences ◽  
Research Attention ◽  
Seagrass Meadows ◽  
Idotea Baltica ◽  
Published Evidence ◽  
Sarpa Salpa

The functional importance of herbivory in seagrass beds is highly variable among systems. In Mediterranean seagrass meadows, macroherbivores, such as the fish Sarpa salpa and the sea urchin Paracentrotus lividus, have received most research attention, so published evidence highlights their importance in seagrass consumption. The role of small crustaceans in seagrass consumption remains less studied in the region. Herbivory on Posidonia oceanica seeds has not previously been reported. In turn, crustacean herbivory on P. oceanica leaves is broadly recognized, although the species feeding on the seagrass are mostly unknown (except for Idotea baltica). This work evaluates P. oceanica consumption by two species of amphipod crustaceans commonly found in seagrass meadows. Ampithoe ramondi and Gammarella fucicola actively feed on P. oceanica leaves and seeds. Both species preferred seeds to leaves only when the seed coat was damaged. This study provides the first direct evidence of consumption of P. oceanica seeds by the two named amphipod crustaceans, and confirms that they also consume leaves of this seagrass species.

scholarly journals Posidonia oceanica molecular adaptation to the light environment

2015 ◽  
Author(s):  
Gabriele Procaccini ◽  
Emanuela Dattolo ◽  
Chiara Lauritano ◽  
Miriam Ruocco ◽  
Lazaro Marin-Guirao
Keyword(s):  
Environmental Changes ◽  
Light Availability ◽  
Posidonia Oceanica ◽  
Light Sensitivity ◽  
Light Environment ◽  
Molecular Adaptation ◽  
Important Species ◽  
Light Regimes ◽  
Seagrass Meadows ◽  
The Impact

Seagrass meadows are among the most productive ecosystems, with Posidonia oceanica being the most important species along the Mediterranean coastline. This species forms extensive mono-specific meadows that are extremely sensitive to medium-high levels of disturbance and are being threatened by fast environmental changes caused by global warming and increasing human activities. The impact can either reflect in higher turbidity along the water column and in increased UV radiation, making the light availability one of the most important factors affecting P. oceanica distribution. Plants developed mechanisms of adaptations at multiple levels to track and cope with fluctuations and changes in the light environment. At molecular level, the modulation of gene expression in response to environmental changes allows plants to optimize the utilization of light energy for growth and to prevent damages due to its excess. To detect the relevant molecular adaptation strategies evolved by P. oceanica and to assess the plasticity showed in the acclimation under different light regimes, we are employing studies both in natural and controlled conditions. Here, we describe the differences in photo acclimation of plants living along the bathymetric cline observed in field and in a common garden experiment in mesocosms, after the exposition to contrasting light regimes. Using a transcriptional approach (both RT -qPCR and RNA-seq) coupled with a physiological one, we are also testing potential divergences existing among populations and individuals related to light sensitivity. These data should supply new insights for the management of seagrasses ecosystems, for the development of most successful transplantation strategies and ultimately for conservation of biodiversity of these precious ecosystems.

scholarly journals Terrestrial-type nitrogen-fixing symbiosis between seagrass and a marine bacterium

Nature ◽  
2021 ◽  
Author(s):  
Wiebke Mohr ◽  
Nadine Lehnen ◽  
Soeren Ahmerkamp ◽  
Hannah K. Marchant ◽  
Jon S. Graf ◽  
...  
Keyword(s):  
Amino Acids ◽  
Marine Bacterium ◽  
Posidonia Oceanica ◽  
Flowering Plants ◽  
Land Plants ◽  
Seagrass Meadows ◽  
Marine Habitats ◽  
Intimate Association ◽  
Related Plant ◽  
Early Land

AbstractSymbiotic N2-fixing microorganisms have a crucial role in the assimilation of nitrogen by eukaryotes in nitrogen-limited environments1–3. Particularly among land plants, N2-fixing symbionts occur in a variety of distantly related plant lineages and often involve an intimate association between host and symbiont2,4. Descriptions of such intimate symbioses are lacking for seagrasses, which evolved around 100 million years ago from terrestrial flowering plants that migrated back to the sea5. Here we describe an N2-fixing symbiont, ‘Candidatus Celerinatantimonas neptuna’, that lives inside seagrass root tissue, where it provides ammonia and amino acids to its host in exchange for sugars. As such, this symbiosis is reminiscent of terrestrial N2-fixing plant symbioses. The symbiosis between Ca. C. neptuna and its host Posidonia oceanica enables highly productive seagrass meadows to thrive in the nitrogen-limited Mediterranean Sea. Relatives of Ca. C. neptuna occur worldwide in coastal ecosystems, in which they may form similar symbioses with other seagrasses and saltmarsh plants. Just like N2-fixing microorganisms might have aided the colonization of nitrogen-poor soils by early land plants6, the ancestors of Ca. C. neptuna and its relatives probably enabled flowering plants to invade nitrogen-poor marine habitats, where they formed extremely efficient blue carbon ecosystems7.

scholarly journals Patch types in Posidonia oceanica meadows around Corsica: How can we use them in seascape ecology?

2015 ◽  
Author(s):  
Arnaud Abadie ◽  
Marina Bonacorsi ◽  
Sylvie Gobert ◽  
Pierre Lejeune ◽  
Gérard Pergent ◽  
...  
Keyword(s):  
Large Scale ◽  
Water Movement ◽  
Human Impacts ◽  
Structural Characteristics ◽  
Posidonia Oceanica ◽  
Radius Of Gyration ◽  
Index Number ◽  
Fish Farms ◽  
Patch Type ◽  
Seagrass Meadows

The meadows formed by the Mediterranean seagrass Posidonia oceanica are subjected to various natural (e.g., water movement, light availability, sedimentation) and anthropogenic (e.g., anchoring, trawling, fish farms, explosives) phenomena that erode them and create diverse types of patches. The assemblage of the P. oceanica matrix and these patches creates particular seascapes. On the basis of this assessment, we aimed to investigate the importance of the patch type in structuring P. oceanica seascapes and to offer new prospects in the large scale studies of seagrass meadows. Five sites encompassing large P. oceanica meadows ranging from 1.86 km² to 4.42 km² along the Corsican coast (France) were considered. Eleven patch types with different sizes, shapes and origins were identified using side scan sonar images (sonograms). Five were recognized as natural and five as anthropogenic. One can be of both origins. The resolution of the sonograms allowed to detect patches of various sizes ranging from 1 m² to 111 829 m². The relation between structural characteristics of patches and the whole seascape aspect was explored using seven landscape metrics relevant for the study of meadows patchiness (patch area, mean radius of gyration, area-weighted radius of gyration, coefficient of variation of the Euclidean nearest-neighbor distance, area-weighted perimeter-area ratio, landscape division index, number of patches). Only a small number of patch types appears to play the strongest role in the characterization of the P. oceanica seascapes. Furthermore, the use of seascape structures seems to be suitable for the development of new tools like indices for the assessment of human impacts on P. oceanica meadows. In this perspective we propose a new and simple index, the Patchiness Source Index (PaSI), to estimate the origin of the patchiness (natural or anthropogenic) for a given area. A landscape approach, as well as information on patch dynamic, should be integrated in the new indices that aim to assess the state of conservation of the whole P. oceanica ecosystem.

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