The role of the seagrass Posidonia oceanica in the cycling of trace elements

The aim of this study was to investigate the role of the seagrass Posidonia oceanica on the cycling of a wide set of trace elements (Ag, As, Ba, Bi, Cd, Co, Cr, Cs, Cu, Fe, Ga, Li, Mn, Ni, Pb, Rb, Sr, Tl, V and Zn). We measured the concentration of these trace elements in different compartments of P. oceanica (leaves, rhizomes, roots and epiphytes) in a non-polluted seagrass meadow representative of the Mediterranean and calculated the annual budget from a mass balance. We provide novel data on accumulation dynamics of many trace elements in P. oceanica compartments and demonstrate that trace element accumulation patterns are mainly determined by plant compartment rather than by temporal variability. Epiphytes were the compartment, which showed the greatest concentrations for most trace elements. Thus, they constitute a key compartment when estimating trace element transfer to higher trophic levels by P. oceanica. Trace element translocation in P. oceanica seemed to be low and acropetal in most cases. Zn, Cd, Sr and Rb were the trace elements that showed the highest release rate through decomposition of plant detritus, while Cs, Tl and Bi showed the lowest. P. oceanica acts as a sink of potentially toxic trace elements (Ni, Cr, As and Ag), which can be sequestered, decreasing their bioavailability. P. oceanica may have a relevant role in the cycling of trace elements in the Mediterranean.This study was funded by the General Secretariat for Research and Technology (IBIS Project) and facilitated by the COST Action ES0906 “Seagrass Productivity: from genes to ecosystem management”. CS was supported by the Ministerio de Educación y Ciencia of Spain

Seagrass sedimentary deposits as security vaults and time capsules of the human past

Seagrass meadows form valuable ecosystems, but are considered to have low cultural value due to limited research efforts in this field. We provide evidence that seagrass deposits play a hitherto unrealized central role in preserving valuable submerged archaeological and historical heritage across the world, while also providing an historical archive of human cultural development over time. We highlight three case studies showing the significance of seagrass in protecting underwater cultural heritage in Denmark, the Mediterranean and Australia. Moreover, we present an overview of additional evidence compiled from the literature. We emphasize that this important role of seagrasses is linked to their capacity to form thick sedimentary deposits, accumulating over time, thereby covering and sealing submerged archaeological heritage. Seagrass conservation and restoration are key to protecting this buried heritage while also supporting the role of seagrass deposits as carbon sinks as well as the many other important ecosystem functions of seagrasses. © 2018, The Author(s)

Environmental variability and heavy metal concentrations from five lagoons in the Ionian Sea (Amvrakikos Gulf, W Greece)

Background: Coastal lagoons are ecosystems of major importance as they host a number of species tolerant to disturbances and they are highly productive. Therefore, these ecosystems should be protected to ensure stability and resilience. The lagoons of Amvrakikos Gulf form one of the most important lagoonal complexes in Greece. The optimal ecological status of these lagoons is crucial for the well-being of the biodiversity and the economic prosperity of the local communities. Thus, monitoring of the area is necessary to detect possible sources of disturbance and restore stability. New information: The environmental variables and heavy metals concentrations, from five lagoons of Amvrakikos Gulf were measured from seasonal samplings and compared to the findings of previous studies in the area, in order to check for possible sources of disturbance. The analysis, showed that i) the values of the abiotic parameters vary with time (season), space (lagoon) and with space over time; ii) the variability of the environmental factors and enrichment in certain elements is naturally induced and no source of contamination is detected in the lagoons

MAREA PROJECT : MEDISEH (Mediterranean Sensitive Habitats) specific contract no 2 (SI2.600741)

Based on the following Terms of Reference (TOR) of the content of the European Commission DG MARE request Ares (2011)665688: “Compile information supporting the identification and location of nursery areas (juveniles in their first and, if appropriate, second year of life) and spawning aggregations. This information, which is to be collated and archived in formats adequate for GIS rendering, shall refer to all the demersal and small pelagic species in the Mediterranean included in Appendix VII of Council Regulation (EC) No 199/2008 as well as for the species subject to minimum size (Council Regulation (EC) No 1967/2006-Annex III). In addition, ecological characterisation of these areas, both in terms of biological community (assemblage) and habitats therein, must be provided.” The technical tender form of the Specific Contract 2 (MEDISEH) defined the following objectives: Review of historical and current data on the locations and the status of seagrass beds, coralligenous and mäerl beds in different GSAs (Geographical Sub-Areas amending amending the Resolution GFCM/31/2007/2) all over the Mediterranean basin. Transform the information into a digitilized format within the framework of a geodatabase Review and map of all existing specific Marine Protected Areas (MPAs) in the Mediterranean area as well as areas that are under any form of national or international regulation. Identify and map suitable areas for Posidonia, coralligenous and mäerl communities by developing habitat distribution models at different spatial scales. Review and map all existing information on historical and current data of nurseries and spawning grounds of certain small pelagic (i.e., Engraulis encrasicolus, Sardina pilchardus, Scomber spp., Trachurus spp.) and demersal species (i.e., Aristaeomorpha foliacea, Aristeus antennatus, Merluccius merluccius, Mullus barbatus, Mullus surmuletus, Nephrops norvegicus, Parapenaeus longirostris, Pagellus erythrinus, Galeus melastomus, Raja clavata, Illex coindetti, Eledone cirrosa) that are included in the Data Collection Framework for the Mediterranean and subjected to minimum landing size based on Council Regulation No 1967/2006-Annex II. Analyze existing survey data and apply spatial analysis techniques in order to identify locations that are more likely to be density hot spot areas or are being more suitable for fish nurseries and spawning grounds for Engraulis encrasicolus, Sardina pilchardus, Scomber spp., Trachurus trachurus, Aristaeomorpha foliacea, Aristeus antennatus, Merluccius merluccius, Mullus barbatus, Mullus surmuletus, Nephrops norvegicus, Parapenaeus longirostris, Pagellus erythrinus, Galeus melastomus, Raja clavata, Illex coindetti, Eledone cirrosa These areas will also be characterized from an environmental and ecological perspective upon data availability. Integrate and present the aforementioned information through a Web-based GIS viewer with an associated geo-referenced database that will operate as a consulting tool for spatial management and conservation planning. Following the revision of the knowledge base, to identify gaps and suggest future research priorities. In order to meet these objectives, an expert team was composed within the MAREA Consortium from scientists with established expertise in the different topics required, and working in different areas of the Mediterranean basin. The team formed to execute the project includes the main Institutes of EU countries in the Mediterranean, all having solid reputations in the fields covered. The participating Institutes/Entities operate in the Western, Central and Eastern parts of the Mediterranean basin, and this ensures familiarity with the geographical areas that are related to the specific tendering. Moreover, a large number of scientists outside of the MAREA Consortium collaborated on a volunteer basis with data and other input. Details on the list of experts and external collaborators can be found in each Work Package in the present report. For CV details, check the MAREA expert web-site http://www.mareaproject.net/.peer-reviewe

Seagrass meadows (Posidonia oceanica) distribution and trajectories of change.

Posidonia oceanica meadows are declining at alarming rates due to climate change and human activities. Although P. oceanica is considered the most important and well-studied seagrass species of the Mediterranean Sea, to date there has been a limited effort to combine all the spatial information available and provide a complete distribution of meadows across the basin. The aim of this work is to provide a fine-scale assessment of (i) the current and historical known distribution of P. oceanica, (ii) the total area of meadows and (iii) the magnitude of regressive phenomena in the last decades. The outcomes showed the current spatial distribution of P. oceanica, covering a known area of 1,224,707 ha, and highlighted the lack of relevant data in part of the basin (21,471 linear km of coastline). The estimated regression of meadows amounted to 34% in the last 50 years, showing that this generalised phenomenon had to be mainly ascribed to cumulative effects of multiple local stressors. Our results highlighted the importance of enforcing surveys to assess the status and prioritize areas where cost-effective schemes for threats reduction, capable of reversing present patterns of change and ensuring P. oceanica persistence at Mediterranean scale, could be implemented.This study was supported and financed by the Commission of the European Union (DG MARE) within the MAREA Framework contract (Call for tenders MARE/2009/05_Lot1) through the Specific Project MEDISEH (SI2.600741): Mediterranean Sensitive Habitats, that received 568.996 euro. The opinions expressed are those of the authors of the study only and do not represent the Commission’s official position. The European Commission is thankfully acknowledged.This is the final version of the article. It first appeared from NPG via http://dx.doi.org/10.1038/srep1250

Effects of high temperature and marine heat waves on seagrasses: Is warming affecting the nutritional value of Posidonia oceanica?

9 pages, 5 figures, 4 tables.-- Under a Creative Commons licensePrimary producers nutritional content affects the entire food web. Here, changes in nutritional value associated with temperature rise and the occurrence of marine heat waves (MHWs) were explored in the endemic Mediterranean seagrass Posidonia oceanica. The variability of fatty acids (FAs) composition and carbon (C) and nitrogen (N) content were examined during summer 2021 from five Mediterranean sites located at the same latitude but under different thermal environments. The results highlighted a decrease in unsaturated FAs and C/N ratio and an increase of monounsaturated FA (MUFA) and N content when a MHW occurred. By contrast, the leaf biochemical composition seems to be adapted to local water temperature since only few significant changes in MUFA were found and N and C/N had an opposite pattern compared to when a MHW occurs. The projected increase in temperature and frequency of MHW suggest future changes in the nutritional value and palatability of leavesThis research was financially supported by Botany and Plant Science at University of Galway, by the project Marine Habitats Restoration in a Climate Change-impaired Mediterranean Sea [MAHRES] funded by the Italian Ministry of Research under the PRIN 2017 Program (Project N. 2017MHHWBN; CUP: 74I19001320001), by “Fondo di Ateneo per la Ricerca 2019” by the University of Sassari, by PON - National Operational Programme - Research and Innovation 2014–2020, PhDs and research contracts on innovation-related topics and by the project DRESSAGE (MIS5045792) (through the Operational Program ‘Competitiveness, Entrepreneurship and Innovation’ (EPAnEK 2014–2020)Peer reviewe

The Future of Blue Carbon Science

The term Blue Carbon (BC) was first coined a decade ago to describe the disproportionately large contribution of coastal vegetated ecosystems to global carbon sequestration. The role of BC in climate change mitigation and adaptation has now reached international prominence. To help prioritise future research, we assembled leading experts in the field to agree upon the top-ten pending questions in BC science. Understanding how climate change affects carbon accumulation in mature BC ecosystems and during their restoration was a high priority. Controversial questions included the role of carbonate and macroalgae in BC cycling, and the degree to which greenhouse gases are released following disturbance of BC ecosystems. Scientists seek improved precision of the extent of BC ecosystems; techniques to determine BC provenance; understanding of the factors that influence sequestration in BC ecosystems, with the corresponding value of BC; and the management actions that are effective in enhancing this value. Overall this overview provides a comprehensive road map for the coming decades on future research in BC science

Dissolved organic carbon fluxes by seagrass meadows and macroalgal beds

Estimates of dissolved organic carbon (DOC) release by marine macrophyte communities (seagrass meadows and macroalgal beds) based on in situ benthic chambers from published and unpublished are compiled in this study. The effect of temperature and light availability on DOC release by macrophyte communities was examined. Almost 85% of the seagrass communities and all of macroalgal communities examined acted as net sources of DOC. Net DOC fluxes in seagrass communities increase positively with water temperature. In macroalgal communities net DOC fluxes under light exceeded those under dark condition, however, this trend was weaker in seagrass communities. Shading of a mixed seagrass meadow in The Philippines led to a significant reduction on the net DOC release when shading was maintained for 6 days compared to only 2 days of shading. Net DOC fluxes increased with increasing community respiration, but were independent of primary production or net community production. The estimated global net DOC flux, and hence export, from marine macrophytes is about 0.158 ± 0.055 or 0.175 ± 0.056 Pg C year−1 depending on the global extent of seagrass meadows considered.This work was funded by the European Commission projects EUROTROPH (contract EVK3-CT-2000-00040), PREDICT (contract IC18-CT98-0292), M&M's (contract EVK3-CT-2000-00044), the Spanish Plan of I+D (REN2001-4977-E) and IBIS project, co-financed by European Social Fund and the Greek Ministry of Development-GSRT.Peer reviewedPeer Reviewe

Reduced carbon sequestration in a Mediterranean seagrass (Posidonia oceanica) ecosystem impacted by fish farming

We studied the relationship between sediment nutrient enrichment and carbon sequestration, using the ratio of gross primary production to respiration (P/R), in a fish-farming impacted and an unaffected Mediterranean seagrass (Posidonia oceanica) ecosystem in the Aegean Sea, Greece. Carbon (C), nitrogen (N) and phosphorus (P) sedimentation, nutrient pools in sediment and dissolved nutrients in pore water were significantly and positively intercorrelated, indicating close linkage between sedimentation and sediment nutrient pools in seagrass meadows. C, N and P sediment pools were significantly enhanced in the impacted meadow throughout the year, even during winter when fish farming activity was low. In the impacted sediment, the increase in C and N was higher than P, reflecting a faster remineralization and uptake of P than C and N. The ecosystem P/R ratio decreased exponentially with sediment nutrient enrichment. Threshold values are given for C, N and P sedimentation rates and sediment pools, and for N and P concentrations in pore waters, after which P/R ratio in the seagrass meadow decreases below 1, indicating a shift from autotrophy to heterotrophy with sediment nutrient enrichment. Such a regime shift indicates a loss of storage capacity of the seagrass ecosystem, jeopardizing the key role of P. oceanica as a carbon sink in the Mediterranean. © Inter-Research 2011.This work was co-funded by the EUEuropean Social Fund (75%) and the Greek Ministry of Development-GSRT (25%) (IBIS Project).Peer Reviewe

Degrading seagrass (Posidonia oceanica) ecosystems: a source of dissolved matter in the Mediterranean

Diurnal variation of dissolved oxygen (DO), organic and inorganic carbon (DOC, DIC), nitrogen (DON, DIN), and phosphorus (DOP, DIP) flux across the sediment–water interface was assessed in fish farm impacted and pristine seagrass (Posidonia oceanica) meadows in the Aegean Sea (Greece). DIC consumption decreased by 52% and DO production decreased by 60% in the light, suggesting reduced photosynthetic performance of the plant community under the fish cages probably due to organic matter loading. In light there was 4 and 15 times higher release of dissolved inorganic and organic matter, respectively, compared to dark incubations under the cages, indicating that fish farming impact is more intense during daytime. DO was taken up, while DIC was released in the dark in both stations, representing a direct measure of mineralization. Dissolved inorganic matter flux (as the sum of DIN and DIP fluxes) was positively related to DIC flux, rendering mineralization as the main driver of nutrient flux under the cages. On average, the impacted meadow released DIN and DIP both in light and dark, while efflux of dissolved organic matter (as the sum of DOC, DON, and DOP fluxes) increased by 132% in the light and by 21% in the dark, implying that the degrading seagrass meadow is a source of dissolved matter to the surrounding water. Shoot density and leaf production were negatively correlated with both diel DIN and DIP fluxes, showing that meadow regression is accompanied by DIN and DIP release from the sediment. Hence, nutrient efflux can adequately illustrate meadow deterioration and, therefore, can be used as indicator of P. oceanica community health.Este trabajo forma parte del Proyecto IBIS, co-financiado por la UE y el Fondo Social Europeo (75%) y el Ministerio de Desarrollo Griego-GSRT (25%)Peer reviewe