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Este artículo contiene 18 páginas, 4 figuras., 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., This paper was supported by Euromarine. Joaquim Garrabou acknowledges the funding by the “Severo Ochoa Centre of Excellence” (CEX2019-000928-S), the MCIU/AEI/FEDER [HEATMED; RTI2018-095346-B-I00], Interreg-Med Programme MPA-Engage (1MED15_3.2_M2_337), the European Union Horizon 2020 research and innovation programme (Futuremares SEP-210597628). Nuria Teixido acknowledges the French National Research Agency (4Oceans-MOPGA grant, ANR-17-MPGA-0001) and internal funds from the Stazione Zoologica Anton Dohrn. Gil Rilov was supported by the Israel Ministry of Environmental Protection. Hocein Bazairi, Free Spinosa, and Vasilis Gerovasileiou acknowledge the funding by the MAVA Fondation (MedKeyHabitats I Project) and the European Commission (Ecap-MED II Project; projects implemented by UNEP/MAP-RAC/SPA). Alfonso Ramos was supported the CIESM “Tropical Signals,” Stelios Katsanevakis and Maria Sini were supported by the Project “Coastal Environment Observatory and Risk Management in Island Regions AEGIS+” (MIS 5047038), implemented within the Operational Programme “Competitiveness, Entrepreneurship and Innovation” (NSRF 2014–2020), co-financed by the Hellenic Government (Ministry of Development and Investments) and the European Union (European Regional Development Fund, Cohesion Fund), Stelios Katsanevakis, Maria Sini and Vasilis Gerovasileiou acknowledge the support of the MARISCA Project, co-funded by 85% by the EEA GRANTS, 2009–2014, and 15% by the Public Investments Programme (PIP) of the Hellenic Republic. Ivan Guala and Daniele Grech thanks thank the support of the project “Pinna nobilis—ricerca per la sopravvivenza: un'iniziativa di Citizen Science per tracciare la mortalità di massa di Pinna nobilis in Sardegna” project and the L/7 grant (CUP 87G17000070002) funded by the Regione Autonoma Sardegna. Jean-Baptiste Ledoux was funded by an assistant researcher contract framework of the RD Unit—UID/Multi/04423/2019—Interdisciplinary Centre of Marine and Environmental Research—financed by the European Regional Development Fund (ERDF) through COMPETE2020—Operational Program for Competitiveness and Internationalization (POCI) and national funds through FCT/MCTES (PIDDAC). This research was supported by the Strategic Funding UIDB/04423/2020 and UIDP/04423/2020 through national funds provided by the FCT—Foundation for Science and Technology and European Regional Development Fund (ERDF), in the framework of the program PT2020. Bernat Hereu and Cristina Linares acknowledge the support of the long-term monitoring programme of the catalan Natural Parks, funded by the Departament de Territori i Sostenibilitat of the Generalitat de Catalunya. Cristina Linares acknowledges the support of the ICREA Academia programme. David Díaz acknowledges the support the research grant CTM2016-77027-R of the Programa Estatal de Investigación, Desarrollo e Innovación Orientada a los Retos de la Sociedad and Program of Marines Strategies of Spain funded by MITERD. Jamila Ben Soussi was partially funded by the Fondation Albert 2 Monaco (MIMOSA Project) and the Tropical Signals Program of CIESM. Giovanni Chimienti was supported by the Italian Ministry of Education, University and Research (PON 2014–2020, AIM 1807508–1, Linea 1), by the Ente Parco Nazionale del Gargano (Research agreement with CoNISMa N. 21/2018), and by the National Geographic Society (Grant EC-176R-18). Nathaniel Bensoussan acknowledges financial support from the European Commission through the programme “Caroline Herschell” in the context of the action “Developing Downstream applications and services on BIO-PHYsical characterization of the seascape for COASTal management” (BIOPHYCOAST). Monica Montefalcone and Annalissa Azzola collected some of their data on MMEs in the frame of the project “Mare Caldo” funded by Greenpeace Italy. Núria Marbà acknowledges financial support from the Spanish Ministries of Economy and Competitiveness (CTM2012-32603, CGL2015-71809-P) and Ministerio de Ciencia, Innovación y Universidades (RTI2018-095441-B-C21). Diego K. Kersting acknowledges support by the postdoctoral fellowship programme Beatriu de Pinós funded by the Secretary of Universities and Research (Government of Catalonia) and the Horizon 2020 programme of research and innovation of the European Union under the Marie Sklodowska-Curie grant agreement No 801370.

Workshop sobre Reservas Marinas - Workshop on Marine Reserves (REMAR 2020), 1-3 July 2020, Barcelona.-- 2 pages, Mediterranean gorgonians are foundation species that support the high diversity associated with Mediterranean coralligenous assemblages. Through the formation of 3D structures, they provide structural complexity and thereby habitat and refugia to numerous associated species, among other ecological benefits. However, these organisms are especially vulnerable to the increasingly frequent and intense marine heatwaves (MHWs). In recent decades, MHWs deeply impacted octocoral species such as the red coral Corallium rubrum and the red gorgonian Paramuricea clavata across large geographical scales, leading to mass mortality events (MMEs). Although the MME immediate and mid-term (3-4 years) effects on the population dynamics of these species are well documented, a long-term evaluation of the impacted populations trajectories is still lacking. This hinders our understanding of the recovery capacity of these key species, and thus ofthe potential delayed effects that MMEs could have on their associated communities. In this study, we performed a long-term status assessment of different populations of P. clavata and C. rubrum that were affected by the MME occurred in the summer of 2003in Scandola Marine Protected Area (MPA), Corsica. Our results show that since 2003, impacted populations have followed different trajectories in terms of density, size structure or tissue necrosis, but a general progressive reduction in biomass. This indicates that the affected populations have no recovered over almost two decades, despite the high protection regime existing in the MPA. Furthermore, many populations followed collapse trajectories that have brought them to the brink of ecological extinction, probably due to the MHW recurrence observed since 2003. Since Mediterranean octocorals play a unique role on the functioning of coralligenous assemblages, the long-term delayed effects of the MME observed in our study underpins the relevant role that stochastic climatic events can play not only on their population dynamics, but also for the future functioning of coralligenous assemblages, D.G-G. is supported by an FPU grant (FPU15/05457) from the Spanish Ministry of Education. We acknowledge the funding support of the European Union’s Horizon 2020 research and innovation program under grant agreement No 689518 (MERCES), the MPA-ENGAGE, Interreg Med Programme, Project co-financed by the European Regional Development Fund and the HEATMED project (RTI2018-095346-BI00) financed by the Spanish Ministry of Science, Innovation and Universities

Este artículo contiene 13 páginas, 6 figuras, 2 tablas., Predators exert a strong influence on ecological communities by reducing the abundance of prey (consumptive effects) and shaping their foraging behavior (non-consumptive effects). Although the prevalence of trophic cascades triggered by non-consumptive effects is increasingly recognized in a wide range of ecosystems, how its relative strength changes as prey individuals grow in size along various life stages remains poorly resolved. We investigated how the effects of predators vary with the ontogeny of a key herbivorous sea urchin, which is responsible for transforming diverse macroalgal forests to a barren state dominated by bare rock and encrusting coralline algae. We conducted a series of field and laboratory experiments to determine how susceptibility to predation, prey behavioral responses, and grazing impact on algal cover vary with sea urchin size. The consumptive effects of predators were greater on smaller sea urchin size classes, which were more susceptible to predation. Unexpectedly however, predator non-consumptive effects acted only on larger sea urchins, significantly reducing their grazing activity in the presence of predator cues. Crucially, only these larger sea urchins were capable of overgrazing macroalgae in the field, with non-consumptive effects reducing sea urchin foraging activity and macroalgal grazing impact by 60%. The decoupling between risk and fear as prey grow indicates that the strength of consumptive and non-consumptive trophic cascades may act differently at different ontogenetic stages of prey. While the consumptive effects of predators directly influence population numbers, the consequences of non-consumptive effects may far outlive consumptive effects as prey grow, finding refuge in size, but not from fear., The Spanish Ministry of Science and Innovation funded this research (UMBRAL; Respuestas de la vegetaci on marina bent onica al estr es: transiciones cr ıticas, resiliencia y oportunidades de gesti on’, CTM2017-86695-C3-3-R) and supported J. Boada’s scholarship (no. BES-2011-043630). The Spanish National Research Council supported R. Arthur’s visitorship with the Memorandum of Understanding between CEAB-IMEDEA-NCF. J. Boada acknowledges the funding received by the Australian Government (ERF_PDR_5888_2017). J. F. Pag es acknowledges financial support from the Welsh Government and Higher Education Funding Council for Wales through the S^er Cymru National Research Network for Low Carbon, Energy and Environment.

The community structure of shallow rocky reef fish fauna of the Azores Archipelago is described from underwater visual censuses carried out at eight areas (Terceira and Corvo Islands). A total of 52 fish species from 26 different families was observed, and the ten most abundant fish corresponded to 82.7% of all fish. Trophic categories are given for observed species with comments on distribution and densities along sampled depth strata. Mean densities along sampled strata were tested for significant differences.Sparidae, LabridaeandCarangidaewere the most speciose families beingDiplodus sargus, Pagellus acarne, Coris julis, Thalassoma pavoandTripterygion delaisithe most abundant species that consequently also accounted for the highest densities.

We tested the effect of reef complexity (number of small vs. large topographic elements, 1 m, respectively), and composition of macroalgae (cover of the kelp Ecklonia radiata, fucalean and red algae) on the abundance patterns of labrid fishes across ~800 km of coastline in south-western Australia. Fishes and habitat attributes were visually counted at 12 reefs visited at four times over 1 year. Five labrids (Austrolabrus maculatus, Coris auricularis, Notolabrus parilus, Ophthalmolepis lineolata and Pseudolabrus biseralis) were frequently observed (>20% of counts), while three species (Bodianus axillaris, Choerodon rubescens and Thalassoma lutescens) were rarely censused (< 6%). Patterns of abundance were generally affected by two descriptors of the habitat structure: the number of small topographic elements (100 m−2), and the percentage of red algal cover. Most species showed a tendency for an increase in their abundances with an increase in the number of small topographic elements and cover of red algae. The patterns likely reflect an underlying correlation between habitat structure and prey accessibility and lowered predation risk.