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Hall-Spencer, Jason

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  • Elevated trace elements in sediments and seagrasses at CO2 seeps
    Publication . Mishra, Amrit Kumar; Santos, Rui; Hall-Spencer, Jason
    Seagrasses often occur around shallow marine CO2 seeps, allowing assessment of trace metal accumulation. Here, we measured Cd, Cu, Hg, Ni, Pb and Zn levels at six CO2 seeps and six reference sites in the Mediterranean. Some seep sediments had elevated metal concentrations; an extreme example was Cd which was 43x more concentrated at a seep site than its corresponding reference site. Three seeps had metal levels that were predicted to adversely affect marine biota, namely Vulcano (for Hg), Ischia (for Cu) and Paleochori (for Cd and Ni). There were higher-than-sediment levels of Zn and Ni in Posidonia oceanica and of Zn in Cymodocea nodosa, particularly in roots. High levels of Cu were found in Ischia seep sediments, yet seagrass was abundant there, and the plants contained low levels of Cu. Differences in bioavailability and toxicity of trace elements helps explain why seagrasses can be abundant at some CO2 seeps but not at others.
  • The future of the northeast Atlantic benthic flora in a high CO2 world
    Publication . Brodie, Juliet; Williamson, Christopher J.; Smale, Dan A.; Kamenos, Nicholas A.; Mieszkowska, Nova; Santos, Rui; Cunliffe, Michael; Steinke, Michael; Yesson, Christopher; Anderson, Kathryn M.; Asnaghi, Valentina; Brownlee, Colin; Burdett, Heidi L.; Burrows, Michael T.; Collins, Sinead; Donohue, Penelope J. C.; Harvey, Ben; Foggo, Andrew; Noisette, Fanny; Nunes, Joana; Ragazzola, Federica; Raven, John A.; Schmidt, Daniela N.; Suggett, David; Teichberg, Mirta; Hall-Spencer, Jason
    Seaweed and seagrass communities in the northeast Atlantic have been profoundly impacted by humans, and the rate of change is accelerating rapidly due to runaway CO2 emissions and mounting pressures on coastlines associated with human population growth and increased consumption of finite resources. Here, we predict how rapid warming and acidification are likely to affect benthic flora and coastal ecosystems of the northeast Atlantic in this century, based on global evidence from the literature as interpreted by the collective knowledge of the authorship. We predict that warming will kill off kelp forests in the south and that ocean acidification will remove maerl habitat in the north. Seagrasses will proliferate, and associated epiphytes switch from calcified algae to diatoms and filamentous species. Invasive species will thrive in niches liberated by loss of native species and spread via exponential development of artificial marine structures. Combined impacts of seawater warming, ocean acidification, and increased storminess may replace structurally diverse seaweed canopies, with associated calcified and noncalcified flora, with simple habitats dominated by noncalcified, turf-forming seaweeds.
  • The future of Blue Carbon science
    Publication . Macreadie, Peter I.; Anton, Andrea; Raven, John A.; Beaumont, Nicola; Connolly, Rod M.; Friess, Daniel A.; Kelleway, Jeffrey J.; Kennedy, Hilary; Kuwae, Tomohiro; Lavery, Paul S.; Lovelock, Catherine E.; Smale, Dan A.; Apostolaki, Eugenia T.; Atwood, Trisha B.; Baldock, Jeff; Bianchi, Thomas S.; Chmura, Gail L.; Eyre, Bradley D.; Fourqurean, James W.; Hall-Spencer, Jason; Huxham, Mark; Hendriks, Iris; Krause-Jensen, Dorte; Laffoley, Dan; Luisetti, Tiziana; Marbà, Núria; Masque, Pere; McGlathery, Karen J.; Megonigal, J. Patrick; Murdiyarso, Daniel; Russell, Bayden D.; Santos, Rui; Serrano, Oscar; Silliman, Brian R.; Watanabe, Kenta; Duarte, Carlos M.
    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.