Patterns of spatial variation of nutrient content, epiphyte load and shoot size of Posidonia oceanica seagrass meadows (Mediterranean Sea)

2011 ◽  
Vol 33 (2) ◽  
pp. 165-175 ◽  
Author(s):  
Inés Castejón-Silvo ◽  
Jorge Terrados
2021 ◽  
Author(s):  
Alice Madonia ◽  

<p><em>Posidonia oceanica </em>(L.) Delile meadows are considered as the most productive ecosystems of the Mediterranean basin, sequestering and storing significant amount of blue carbon in their rich organic sediments and in their living and non-living biomass and these meadows are identified as a priority habitat type for conservation under the Habitat Directive (Dir 92/43/CEE). Despite the importance of the ecosystem services it provides, this habitat is disappearing at a rate four times as high as that of terrestrial forests, experiencing an alarming reduction due to the impacts of human activities in coastal areas, especially in the north-western side of the Mediterranean Sea. To face this issue, the SeaForest Life project foresees the quantification of carbon deposits and their rate of change related to habitat degradation specifically focusing on the effects caused by boat’s anchors and moorings. The project is realized in the Archipelago of la Maddalena National Park, the Asinara National Park and the Cilento, Vallo di Diano and Alburni National Park, for which ad hoc management plans of mooring are going to be adopted to reduce the impact of this practice on the seagrass meadows. As a first step, an updating of habitat 1120*’s cartography in each of the Marine Protected Areas engaged in the project have been fulfilled, using high definition multispectral imagery. Furthermore, monitoring of the areas with the highest attendance of the anchorages was carried out through the use of medium resolution satellite multi-spectral images using the infrared band, to identify and quantify the degradation and the state of conservation of the <em>P.oceanica</em> meadows present in the investigated areas. The updated cartography has been used to implement the InVEST Coastal Blue Carbon (CBC) which attempts to predict the sequestration, storage and, when degraded, the emissions of carbon by coastal ecosystems, so representing a useful tool for the analysis of the ecological and economic effects of the degradation processes (boats anchoring) and mitigation measures (anchor management plan and eco friendly moorings). Up to now, the InVEST-CBC model has estimated a CO<sub>2</sub> loss due to boats anchoring equal to 2300 tCO<sub>2</sub>/year, using stock and flow data in soil and biomass obtained from the results of the Life Blue Natura project and<em> P. oceanica</em> samples collected in the Cilento National Park. In the future, the results of the model will be improved with data collected in the other two project areas, also through the use of innovative instrumentation. Moreover, the scenarios with the implementation of the mooring management plans will be analyzed in the three study areas. The dataset obtained by the model is being used to define a standard protocol for the estimation of CO<sub>2</sub> fixation by <em>P. oceanica </em>meadows in the Mediterranean Sea. Such protocol will be fundamental for the realization of a national IT-based platform for a voluntary based carbon market to sell and acquire the carbon credits generated by the SeaForest Life project activities, to be extended to all the Mediterranean countries and to be scaled up to new protected marine areas.</p>


Diversity ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 21
Author(s):  
Felix Ivo Rossbach ◽  
Benedikt Merk ◽  
Christian Wild

The Mediterranean Sea comprises habitats such as Posidonia oceanica seagrass meadows that exhibit high associated biodiversity of sessile organisms. Recent pilot research indicates that benthic mats formed by the scarcely investigated fleshy red alga Phyllophora crispa also host a high diversity of benthic fauna. Among the key taxa found in these mats in the recent pilot studies are benthic foraminifera that live as epiphytes on the red algae thalli. Knowledge about their abundance and species richness associated with this habitat in relation to reference habitats is missing. We thus carried out a comparative assessment focusing on foraminifera within samples from P. crispa mats and neighboring P. oceanica meadows on five different sampling sites around Giglio Island in the Tuscan Archipelago (Tyrrhenian Sea, Italy). A total of 104 different foraminiferal taxa were identified, of which a total of 85 taxa were found in P. crispa samples (46 exclusively in this habitat). This biodiversity was higher compared to other studies on phytal habitats in the Mediterranean Sea. The number of foraminiferal taxa associated with P. crispa was significantly higher (average 27.5 ± 8.1 taxa) compared to P. oceanica (leaves average 7.0 ± 3.6, shoots average 7.9 ± 3.4 taxa). The abundance of foraminifera (12,000 individuals m−2 surface area of P. crispa mat) was also higher than in the neighboring P. oceanica meadows (7792 individuals m−2 leaf and 8171 individuals m−2 shoot surface area). The most frequently found taxa across habitats were Miniacina miniacea, Lobatula lobatula, and Sejunctella sp. (24%, 20%, and 6% of the total population, respectively). Our results imply that P. crispa mats host an exceptional diversity of associated foraminifera that is even higher than those associated with seagrass meadows. Red algae mats built by P. crispa may thus be considered as potential refuge habitats and biodiversity reservoirs in management and conservation.


2007 ◽  
Vol 75 (1-2) ◽  
pp. 63-71 ◽  
Author(s):  
M. Montefalcone ◽  
C. Morri ◽  
A. Peirano ◽  
G. Albertelli ◽  
C.N. Bianchi

2020 ◽  
Vol 8 (11) ◽  
pp. 911
Author(s):  
Francesca Iuculano ◽  
Carlos M. Duarte ◽  
Jaime Otero ◽  
Xosé Antón Álvarez-Salgado ◽  
Susana Agustí

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.


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