Browsing by Author "Kennedy, Hilary"
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- Decreasing carbonate load of seagrass leaves with increasing latitudePublication . Mazarrasa, Ines; Marba, Nuria; Krause-Jensen, Dorte; Kennedy, Hilary; Santos, Rui; Lovelock, Catherine E.; Duarte, Carlos M.Seagrass meadows play a significant role in the formation of carbonate sediments, serving as a substrate for carbonate-producing epiphyte communities. The magnitude of the epiphyte load depends on plant structural and physiological parameters, related to the time available for epiphyte colonization. Yet, the carbonate accumulation is likely to also depend on the carbonate saturation state of seawater (Omega) that tends to decrease as latitude increases due to decreasing temperature and salinity. A decrease in carbonate accumulation with increasing latitude has already been demonstrated for other carbonate producing communities. The aim of this study was to assess whether there was any correlation between latitude and the epiphyte carbonate load and net carbonate production rate on seagrass leaves. Shoots from 8 different meadows of the Zostera genus distributed across a broad latitudinal range (27 degrees S to up to 64 degrees N) were sampled along with measurements of temperature and Omega. The Omega within meadows significantly decreased as latitude increased and temperature decreased. The mean carbonate content and load on seagrass leaves ranged from 17% DW to 36% DW and 0.4-2.3 mg CO3 cm(-2), respectively, and the associated mean carbonate net production rate varied from 0.007 to 0.9 mg CO3 cm(-2) d(-1). Mean carbonate load and net production rates decreased from subtropical and tropical, warmer regions towards subpolar latitudes, consistent with the decrease in Omega. These results point to a latitudinal variation in the contribution of seagrass to the accumulation of carbonates in their sediments which affect important processes occurring in seagrass meadows, such as nutrient cycling, carbon sequestration and sediment accretion.
- Seagrass ecosystem services: assessment and scale of benefitsPublication . de los Santos, Carmen B.; Scott, Abbi; Arias-Ortiz, Ariane; Jones, Benjamin; Kennedy, Hilary; Mazarrasa, Inés; McKenzie, Len; Nordlund, Lina Mtwana; de la Torre-Castro, Maricela de la T; Unsworth, Richard K.F.; Ambo-Rappe, Rohani; Potouroglou, M; Grimsditch, G; Weatherdon, L; Lutz, SSeagrass ecosystems provide a wide variety of services that support human well-being around the world (Barbier et al. 2011). It is estimated that more than 1 billion people live within 100 km of a coast with seagrass meadows, thus potentially benefiting from their provisioning, regulating and cultural services. Seagrasses play a significant global role in supporting food security, mitigating climate change, enriching biodiversity, purifying water, protecting the coastline and controlling diseases (Figure 2). The integrity and provision of services by seagrass meadows are enhanced by their proximity and connectivity to other coastal ecosystems such as tidal marshes, coral reefs, mangrove and kelp forests, and oyster and mussel beds. The maintenance and regulation of these services is therefore essential to support human well-being and promote development in the future.
- The future of Blue Carbon sciencePublication . 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.