BUSCADOR RECOLECTA

Our knowledge of the factors that can influence the stock of organic carbon (OC) that is stored in the soil of seagrass meadows is evolving, and several causal effects have been used to explain the variation of stocks observed at local to national scales. To gain a global-scale appreciation of the drivers that cause variation in soil OC stocks, we compiled data on published species-specific traits and OC stocks from monospecific and mixed meadows at multiple geomorphological settings. Species identity was recognized as an influential driver of soil OC stocks, despite their large intraspecific variation. The most important seagrass species traits associated with OC stocks were the number of leaves per seagrass shoot, belowground biomass, leaf lifespan, aboveground biomass, leaf lignin, leaf breaking force and leaf OC plus the coastal geomorphology of the area, particularly for lagoon environments. A revised estimate of the global average soil OC stock to 20 cm depth of 15.4 Mg C ha−1 is lower than previously reported. The largest stocks were still recorded in Mediterranean seagrass meadows. Our results specifically identify Posidonia oceanica from the Mediterranean and, more generally, large and persistent species as key in providing climate regulation services, and as priority species for conservation for this specific ecosystem service.

Data on biogeochemical characteristics (210Pb geochronologies, density, organic matter, organic carbon concentration, stable carbon isotopes, carbon stocks and carbon burial rates) and on the detection of Halophila stipulacea with eDNA in seagrass sediments cores from H. stipulacea, Cymodocea nodosa and Posidonia oceanica meadows collected in the Eastern Mediterranean (Greece and Cyprus)., This work was funded by the Spanish Ministry of Economy and Competiveness (Project MEDSHIFT, CGL2015-71809-P), the Spanish Ministry of Science, Innovation and Universities (SUMAECO, RTI2018-095441-B-C21) and King Abdullah University for Science and Technology (3834 KAUST-CSIC Research Collaboration and base line funding to CMD)., Peer reviewed

A devastating mass mortality event (MME) very likely caused by the protozoan Haplosporidium pinnae first detected in 2016 in the Western Mediterranean Sea, is pushing the endemic bivalve Pinna nobilis to near extinction. Populations recovery, if possible, will rely on larval dispersal from unaffected sites and potential recolonization through recruitment of resistant juveniles. To assess the impact of the MME on the species’ larval recruitment, an unprecedented network of larval collector stations was implemented over several thousands of kilometers along the Western Mediterranean coasts during the 3 years after the onset of the MME. The findings of this network showed a generalized disruption in recruitment with dramatic consequences for the recovery of the species. However, there were exceptions to this pattern and recruits were recorded in a few sites where the resident population had been decimated. This hints to the importance of unaffected populations as larval exporting sources and the role of oceanographic currents in larval transport in the area, representing a beacon of hope in the current extremely worrying scenario for this emblematic species., DK and MV-L were supported by a Juan de la Cierva-Incorporación postdoctoral contract (Spanish Ministry of Science, Innovation and Universities; IJCI-2017-31457 and IJCI-2016-29329, respectively). SK was partially supported by a postdoctoral contract (EU Horizon 2020, Project: MERCES, No. 689518). EÁ was supported by a Technical Support Staff contract (Spanish Ministry of Economy and Competiveness, PTA2015-10829-I). This study was partially funded by: EsMarEs (MITECO), SuMaEco (RTI2018-095441-B-C21, Spanish Ministry of Science, Innovation and Universities) and Prince Albert II of Monaco Foundation (Project BF/HEM 15-1662). The authors acknowledge the MEDCLIC project, funded by “La Caixa” Foundation, contributing to the development of the WMOP hydrodynamic model.

The introduction and establishment of exotic species often result in significant changes in recipient communities and their associated ecosystem services. However, usually the magnitude and direction of the changes are difficult to quantify because there is no pre-introduction data. Specifically, little is known about the effect of marine exotic macrophytes on organic carbon sequestration and storage. Here, we combine dating sediment cores (210Pb) with sediment eDNA fingerprinting to reconstruct the chronology of pre- and post-arrival of the Red Sea seagrass Halophila stipulacea spreading into the Eastern Mediterranean native seagrass meadows. We then compare sediment organic carbon storage and burial rates before and after the arrival of H. stipulacea and between exotic (H. stipulacea) and native (C. nodosa and P. oceanica) meadows since the time of arrival following a Before-After-Control-Impact (BACI) approach. This analysis revealed that H. stipulacea arrived at the areas of study in Limassol (Cyprus) and West Crete (Greece) in the 1930s and 1970s, respectively. Average sediment organic carbon after the arrival of H. stipulacea to the sites increased in the exotic meadows twofold, from 8.4 ± 2.5 g Corg m−2 year−1 to 14.7 ± 3.6 g Corg m−2 year−1, and, since then, burial rates in the exotic seagrass meadows were higher than in native ones of Cymodocea nodosa and Posidonia oceanica. Carbon isotopic data indicated a 50% increase of the seagrass contribution to the total sediment Corg pool since the arrival of H. stipulacea. Our results demonstrate that the invasion of H. stipulacea may play an important role in maintaining the blue carbon sink capacity in the future warmer Mediterranean Sea, by developing new carbon sinks in bare sediments and colonizing areas previously occupied by the colder thermal affinity P. oceanica., This work was funded by the Spanish Ministry of Economy and Competiveness (Project MEDSHIFT, CGL2015-71809-P), the Spanish Ministry of Science, Innovation and Universities (SUMAECO, RTI2018-095441-B-C21) and King Abdullah University for Science and Technology (3834 KAUST-CSIC Research Collaboration and base line funding to CMD). We thank Ioannis Savva, Julius Glampedakis, Scott Bennet and Raquel Vaquer-Sunyer for field assistance and Joan Manuel Bruach for his work on the analysis of 210Pb dating. MW was supported by a PhD contract (BES-2016-078241) of the Spanish Ministry of Science, Innovation and Universities. AA-O was funded by the NOAA C&GC Postdoctoral Fellowship Program administered by UCAR-CPAESS under award #NA18NWS4620043B., Peer reviewed

The variability of La Guajira upwelling system, in the south-central Caribbean Sea, is strongly influenced by the intensity and location of the atmospheric Caribbean Low-Level Jet (CLLJ), a near-surface branch of the easterlies, as well as by the regional ocean circulation. During favorable conditions (i.e., strong easterlies blowing almost parallel to the coast), upwelling is enhanced and a large amount of primary productivity occurs in La Guajira area. In contrast, during relatively mild wind conditions, the CLLJ is misaligned to the coast and the Caribbean Counter Current (CCC, locally also known as the Darien Current), which forms as a branch from the Panama-Colombia Gyre, flows northeastward over the continental shelf advecting waters from the southwestern Caribbean basin toward La Guajira. The CCC has a clear signature at the surface layer that extends from the Darien Gulf toward La Guajira peninsula during mild wind periods, while disappears during the months of strong winds. The direction and the magnitude of the easterlies, and more specifically of the CLLJ, control the position and pathway of the CCC, which extends more than 900 km in the southern Caribbean Sea during May, June, August, September, and October. The high concentration of chlorophyll-a at the sea surface evidenced by satellite-based color images is semi-seasonally modulated by the CLLJ, which during its relaxation phase allows the irruption of the CCC toward the east up to La Guajira., AO acknowledge financial support from Ministerio de Ciencia, Innovación y Universidad through MOCCA project (RTI2018-095441-B-C21). JS thanks the funding received from Generalitat Valenciana and the European Social Fund (ESF) under Grant APOSTD/2020/254. IH-C was supported by the Vicenç Mut grant funded by the Government of the Balearic Island and the ESF. AC-E wants to thank the University of Toulon—France for the support during his postdoctoral research. ÁM was partially supported by the NOAA grant NA18OAR4310275., Peer reviewed

The variability of La Guajira upwelling system, in the south-central Caribbean Sea, is strongly influenced by the intensity and location of the atmospheric Caribbean Low-Level Jet (CLLJ), a near-surface branch of the easterlies, as well as by the regional ocean circulation. During favorable conditions (i.e., strong easterlies blowing almost parallel to the coast), upwelling is enhanced and a large amount of primary productivity occurs in La Guajira area. In contrast, during relatively mild wind conditions, the CLLJ is misaligned to the coast and the Caribbean Counter Current (CCC, locally also known as the Darien Current), which forms as a branch from the Panama-Colombia Gyre, flows northeastward over the continental shelf advecting waters from the southwestern Caribbean basin toward La Guajira. The CCC has a clear signature at the surface layer that extends from the Darien Gulf toward La Guajira peninsula during mild wind periods, while disappears during the months of strong winds. The direction and the magnitude of the easterlies, and more specifically of the CLLJ, control the position and pathway of the CCC, which extends more than 900 km in the southern Caribbean Sea during May, June, August, September, and October. The high concentration of chlorophyll-a at the sea surface evidenced by satellite-based color images is semi-seasonally modulated by the CLLJ, which during its relaxation phase allows the irruption of the CCC toward the east up to La Guajira., AO acknowledge financial support from Ministerio de Ciencia, Innovación y Universidad through MOCCA project (RTI2018-095441-B-C21). JS thanks the funding received from Generalitat Valenciana and the European Social Fund (ESF) under Grant APOSTD/2020/254. IH-C was supported by the Vicenç Mut grant funded by the Government of the Balearic Island and the ESF. AC-E wants to thank the University of Toulon—France for the support during his postdoctoral research. ÁM was partially supported by the NOAA grant NA18OAR4310275.

Climate change is causing an increase in the frequency and intensity of marine heatwaves (MHWs) and mass mortality events (MMEs) of marine organisms are one of their main ecological impacts. Here, we show that during the 2015–2019 period, the Mediterranean Sea has experienced exceptional thermal conditions resulting in the onset of five consecutive years of widespread MMEs across the basin. These MMEs affected thousands of kilometers of coastline from the surface to 45 m, across a range of marine habitats and taxa (50 taxa across 8 phyla). Significant relationships were found between the incidence of MMEs and the heat exposure associated with MHWs observed both at the surface and across depths. Our findings reveal that the Mediterranean Sea is experiencing an acceleration of the ecological impacts of MHWs which poses an unprecedented threat to its ecosystems' health and functioning. Overall, we show that increasing the resolution of empirical observation is critical to enhancing our ability to more effectively understand and manage the consequences of climate change., French National Research Agency. Grant Number: ANR-17-MPGA-0001; H2020 Environment. Grant Number: SEP-210597628; Interreg Med. Grant Number: 1MED15_3.2_M2_337; Marie Sklodowska-Curie. Grant Number: 801370; Beatriu de Pinós funded by the Secretary of Universities and Research (Government of Catalonia); Ministerio de Ciencia, Innovación y Universidades. Grant Number: RTI2018-095441-B-C21; Spanish Ministries of Economy and Competitiveness. Grant Numbers: CGL2015-71809-P, CTM2012-32603; Greenpeace Italy; National Geographic Society. Grant Number: EC-176R-18; Ente Parco Nazionale del Gargano; Italian Ministry of Education, University and Research. Grant Numbers: AIM 1807508–1, PON 2014–2020; Tropical Signals Program of CIESM; Fondation Albert 2 Monaco (MIMOSA Project); MITERD. Grant Number: CTM2016-77027-R; Departament de Territori i Sostenibilitat of the Generalitat de Catalunya; FCT—Foundation for Science and Technology. Grant Numbers: UIDP/04423/2020, UIDB/04423/2020; FCT/MCTES (PIDDAC); European Regional Development Fund (ERDF); RD Unit. Grant Number: UID/Multi/04423/2019; Regione Autonoma Sardegna. Grant Number: CUP 87G17000070002; Public Investments Programme (PIP) of the Hellenic Republic; EEA GRANTS; MARISCA Project; European Union (European Regional Development Fund, Cohesion Fund); Hellenic Government (Ministry of Development and Investments); CIESM “Tropical Signals,” Stelios Katsanevakis; European Commission; MAVA Fondation; Israel Ministry of Environmental Protection; Stazione Zoologica Anton Dohrn; MCIU/AEI/FEDER. Grant Number: RTI2018-095346-B-I00; Severo Ochoa Centre of Excellence. Grant Number: CEX2019-000928-S; Euromarine.