Publications

Abstract. Vegetated coastal ecosystems, including tidal marsh, mangrove and seagrass, are being increasingly assessed for their potential in carbon dioxide sequestration worldwide. However, there is a paucity of studies that have effectively estimated the accumulation rates of sediment organic carbon (Corg) beyond the mere quantification of Corg stocks. Here, we discuss the use of the 210Pb dating technique as a practical tool to measure the rate of Corg accumulation in vegetated coastal ecosystems. We critically review the status of 210Pb dating methods of vegetated coastal sediments and assess the limitations that apply to these ecosystems, which are often composed by heterogeneous sediments, abundant in coarse particles, with varying inputs of organic material, and are disturbed by natural and anthropogenic processes causing sediment mixing, changes in sedimentation rates or erosion. Through a range of simulations, we discuss the most relevant processes that impact the 210Pb record in vegetated coastal ecosystems and evaluate the deviations in sediment and Corg accumulation rates produced by anomalies in 210Pb profiles. Our results show that the deviation in the determination of sediment and derived Corg accumulation rates is within 20 % confirming that the 210Pb dating technique is secure. However, while these uncertainties might be acceptable for the determination of mean sediment and Corg accumulation rates over the last century, they may not always allow the determination of a detailed geochronology, historical reconstruction, or to ascertain rates of change and fluxes. Additional tracers or geochemical data need to be used in concert to constrain the 210Pb-derived results and to properly interpret the processes recorded in vegetated coastal sediments. The framework provided in this study can be instrumental in reducing the uncertainties associated to the estimates of Corg accumulation rates in vegetated coastal sediments.

This paper presents lightweight and flexible sensors for conductivity, temperature, and depth (CTD). CTD sensors are heavily used in oceanography to determine the salinity, which is a critical factor in the determination of mixingdensity, currents, weather and more. The graphene sensors are fabricated by laser printing on flexible polyimide. They combine corrosion resistance with a good conductivity and piezoresistivity in a robust platform, enabling the detection of conductance, temperature, and pressure. The performance of the graphene sensor was demonstrated in harsh environments with pressures up to 12 MPa and prolonged exposure to highly saline seawater. The printed sensors are durable and lightweight, making ideal for use as stationary monitory sensors or attached to a wide range of marine animals.

A table of Spearman correlation coefficients for the parameters used in model development.

Abstract. Coastal hypoxia is a problem that is predicted to increase rapidly in the future. At the same time we are facing rising atmospheric CO2 concentrations, which are increasing the pCO2 and acidity of coastal waters. These two drivers are well studied in isolation however; the coupling of low O2 and pH is likely to provide a more significant respiratory challenge for slow moving and sessile invertebrates than is currently predicted. The Gullmar Fjord in Sweden is home to a range of habitats such as sand and mud flats, seagrass beds, exposed and protected shorelines, and rocky bottoms. Moreover, it has a history of both natural and anthropogenically enhanced hypoxia as well as North Sea upwelling, where salty water reaches the surface towards the end of summer and early autumn. A total of 11 species (Crustacean, Chordate, Echinoderm and Mollusc) of these ecosystems were exposed to four different treatments (high/low oxygen and low/high CO2; varying pCO2 of 450 and 1300 ppm and O2 concentrations of 2–3.5 and 9–10 mg L−1) and respiration measured after 3 and 6 days, respectively. This allows us to evaluate respiration responses of species of contrasting habitats and life-history strategies to single and multiple stressors. Results show that the responses of the respiration were highly species specific as we observed both synergetic as well as antagonistic responses, and neither phylum nor habitat explained trends in respiratory responses. Management plans should avoid the generalized assumption that combined stressors will results in multiplicative effects and focus attention on alleviating hypoxia in the region.

Abstract Predictors for the ecological effects of non‐native species are lacking, even though such knowledge is fundamental to manage non‐native species and mitigate their impacts. Current theories suggest that the ecological effects of non‐native species may be related to other concomitant anthropogenic stressors, but this has not been tested at a global scale. We combine an exhaustive meta‐analysis of the ecological effects of marine non‐native species with human footprint proxies to determine whether the ecological changes due to non‐native species are modulated by co‐occurring anthropogenic impacts. We found that non‐native species had greater negative effects on native biodiversity where human population was high and caused reductions in individual performance where cumulative human impacts were large. On this basis we identified several marine ecoregions where non‐native species may have the greatest ecological effects, including areas in the Mediterranean Sea and along the northwest coast of the United States. In conclusion, our global assessment suggests coexisting anthropogenic impacts can intensify the ecological effects of non‐native species.

Abstract Rapid loss of sea ice is opening up the Arctic Ocean to shipping, a practice that is forecasted to increase rapidly by 2050 when many models predict that the Arctic Ocean will largely be free of ice toward the end of summer. These forecasts carry considerable uncertainty because Arctic shipping was previously considered too sparse to allow for adequate validation. Here, we provide quantitative evidence that the extent of Arctic shipping in the period 2011–2014 is already significant and that it is concentrated (i) in the Norwegian and Barents Seas, and (ii) predominantly accessed via the Northeast and Northwest Passages. Thick ice along the forecasted direct trans-Arctic route was still present in 2014, preventing transit. Although Arctic shipping remains constrained by the extent of ice coverage, during every September, this coverage is at a minimum, allowing the highest levels of shipping activity. Access to Arctic resources, particularly fisheries, is the most important driver of Arctic shipping thus far.

Clonal organisms present a particular challenge in population genetics because, in addition to the possible existence of replicates of the same genotype in a given sample, some of the hypotheses and concepts underlying classical population genetics models are irreconcilable with clonality. The genetic structure and diversity of clonal populations was examined using a combination of new tools to analyze microsatellite data in the marine angiosperm Posidonia oceanica. These tools were based on examination of the frequency distribution of the genetic distance among ramets, termed the spectrum of genetic diversity (GDS), and of networks built on the basis of pairwise genetic distances among genets. The properties and topology of networks based on genetic distances showed a topology, characterized by a high degree of connectivity among nodes, and a substantial amount of substructure, revealing organization in sub-families of closely related individuals. Keywords: genetic networks; small-world networks; genetic diversity; clonal organisms

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 133:203-215 (1996) - doi:10.3354/meps133203 Growth patterns of Western Mediterranean seagrasses: species-specific responses to seasonal forcing Marbà N, Cebrián J, Enríquez S, Duarte CM The seasonal growth pattern of the 4 seagrass species occurring in the NW Mediterranean (i.e. Cymodoceanodosa, Zosteranoltii, Z.marina, Posidoniaoceanica) was studied in populations growing in the same locality (Cala Jonquet, Girona, NE Spain), and thus experiencing the same seasonal (i.e. temperature and light) forcing, to evaluate the contribution of species-specific responses to seagrass growth seasonality. C.nodosa, Z.noltii, and Z.marina showed comparable growth patterns as indicated by significant correlations of growth across species (cross correlation, r &GT 0.54, p &LT 0.05). This result provided evidence of a similarity in the response of these species to seasonal forcing. The seasonal pattern of P.oceanica resembled that of the other species in shoot weight, shoot elongation, and ramet recruitment, whereas it differed in internode weight and rhizome elongation. Despite some similarities in seasonal growth patterns, the patterns were lagged by 1 to 2 mo across species, and the magnitude of seasonal growth fluctuations was species-dependent. Species-specific responses of seagrasses to climate forcing should be related to differences in the capacity of the plants to store resources and to the extent of ramet integration among species, both processes being closely related to plant size. Large seagrasses (e.g. P.oceanica), with thick and long-living rhizomes, should be able to store more photoassimilates and to transport them over longer distances than small plants (e.g. C.nodosa), with thinner and shorter-living rhizomes. Large species should, therefore, be able to grow more independently of environmental conditions than small ones. Moreover, C.nodosa showed the greatest response to temperature fluctuations whereas Z.marina growth was strongly coupled to seasonal light conditions, indicating different plant sensitivity to climate fluctuations among species. This study confirms the great variability in seagrass seasonality possible under similar seasonal forcing, and demonstrates that seagrass seasonality has both an extrinsic component, dependent on seasonal forcing of light and temperature, and an intrinsic component. The intrinsic component of seagrass seasonality likely involves a differential capacity of the species to regulate the internal resource economy which may buffer, or amplify, the external seasonal forcing. Posidoniaoceanica . Cymodoceanodosa . Zosteramarina . Zosteranoltii . Seasonality . Module size . Module appearance rate . Module growth . Ramet recruitment . Flowering Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 133. Publication date: March 28, 1996 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1996 Inter-Research.