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This deliverable provides (1) updates to D1.2 ‘Map the current state of biological observations in Europe’, (2) a report on the two workshops and global review undertaken to progress capacity and coordination of ocean observation, and (3) outlines key steps forward that will improve our capacity to predict biological and ecosystem changes under a changing climate.

The global lockdown to mitigate COVID-19 pandemic health risks has altered human interactions with nature. Here, we report immediate impacts of changes in human activities on wildlife and environmental threats during the early lockdown months of 2020, based on 877 qualitative reports and 332 quantitative assessments from 89 different studies. Hundreds of reports of unusual species observations from around the world suggest that animals quickly responded to the reductions in human presence. However, negative effects of lockdown on conservation also emerged, as confinement resulted in some park officials being unable to perform conservation, restoration and enforcement tasks, resulting in local increases in illegal activities such as hunting. Overall, there is a complex mixture of positive and negative effects of the pandemic lockdown on nature, all of which have the potential to lead to cascading responses which in turn impact wildlife and nature conservation. While the net effect of the lockdown will need to be assessed over years as data becomes available and persistent effects emerge, immediate responses were detected across the world. Thus, initial qualitative and quantitative data arising from this serendipitous global quasi-experimental perturbation highlights the dual role that humans play in threatening and protecting species and ecosystems. Pathways to favorably tilt this delicate balance include reducing impacts and increasing conservation effectiveness.

51 pages, 6 figures, Global change is striking harder and faster in the Mediterranean Sea than elsewhere, where high levels of human pressure and proneness to climate change interact in mod- ifying the structure and disrupting regulative mechanisms of marine ecosystems. Rocky reefs are particularly exposed to such environmental changes with ongoing trends of degradation being impressive. Due to the variety of habitat types and associated marine biodiversity, rocky reefs are critical for the functioning of marine ecosystems, and their decline could profoundly affect the provision of essential goods and services which human populations in coastal areas rely upon. Here, we provide an up-to-date overview of the status of rocky reefs, trends in human-driven changes undermining their integrity, and current and upcoming management and conservation strategies, attempting a pro- jection on what could be the future of this essential component of Mediterranean marine ecosystems.

MotivationThe BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene.Main types of variables includedThe database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record.Spatial location and grainBioTIME is a global database of 547,161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km2 (158 cm2) to 100 km2 (1,000,000,000,000 cm2).Time period and grainBioTIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year.Major taxa and level of measurementBioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates.Software format.csv and .SQL.

Contributed by Nancy Knowlton, April 28, 2014 (sent for review November 25, 2013; reviewed by Brian McGill and Fangliang He) Explaining patterns of commonness and rarity is fundamental for understanding and managing biodiversity. Consequently, a key test of biodiversity theory has been how well ecological models reproduce empirical distributions of species abundances. However, ecological models with very different assumptions can predict similar species abundance distributions, whereas models with similar assumptions may generate very different predictions. This complicates inferring processes driving community structure from model fits to data. Here, we use an approximation that captures common features of “neutral” biodiversity models—which assume ecological equivalence of species—to test whether neutrality is consistent with patterns of commonness and rarity in the marine biosphere. We do this by analyzing 1,185 species abundance distributions from 14 marine ecosystems ranging from intertidal habitats to abyssal depths, and from the tropics to polar regions. Neutrality performs substantially worse than a classical nonneutral alternative: empirical data consistently show greater heterogeneity of species abundances than expected under neutrality. Poor performance of neutral theory is driven by its consistent inability to capture the dominance of the communities’ most-abundant species. Previous tests showing poor performance of a neutral model for a particular system often have been followed by controversy about whether an alternative formulation of neutral theory could explain the data after all. However, our approach focuses on common features of neutral models, revealing discrepancies with a broad range of empirical abundance distributions. These findings highlight the need for biodiversity theory in which ecological differences among species, such as niche differences and demographic trade-offs, play a central role. metacommunities | marine macroecology | species coexistence | Poisson-lognormal distribution

Macroalgal forests are one of the most productive and valuable marine ecosystems, but yet strongly exposed to fragmentation and loss. Detailed large-scale information on their distribution is largely lacking, hindering conservation initiatives. In this study, a systematic effort to combine spatial data on Cystoseira C. Agardh canopies (Fucales, Phaeophyta) was carried out to develop a Habitat Suitability Model (HSM) at Mediterranean scale, providing critical tools to improve site prioritization for their management, restoration and protection. A georeferenced database on the occurrence of 20 Cystoseira species was produced collecting all the available information from published and grey literature, web data portals and co-authors personal data. Data were associated to 55 predictor variable layers in the (ASCII) raster format and were used in order to develop the HSM by means of a Random Forest, a very effective Machine Learning technique. Knowledge about the distribution of Cystoseira canopies was available for about the 14% of the Mediterranean coastline. Absence data were available only for the 2% of the basin. Despite these gaps, our HSM showed high accuracy levels in reproducing Cystoseira distribution so that the first continuous maps of the habitat across the entire basin was produced. Misclassification errors mainly occurred in the eastern and southern part of the basin, where large gaps of knowledge emerged. The most relevant drivers were the geomorphological ones, followed by anthropogenic variables proxies of pollution and urbanization. Our model shows the importance of data sharing to combine a large number of spatial and environmental data, allowing to individuate areas with high probability of Cystoseira occurrence as suitable for its presence. This approach encourages the use of this modelling tool for the prediction of Cystoseira distribution and for supporting and planning conservation and management initiatives. The step forward is to refine the spatial information of presence-absence data about Cystoseira canopies and of environmental predictors in order to address species-specific assessments.

The Mediterranean Sea is an enclosed basin connected to the Atlantic through the Strait of Gibraltar in the west and to the Sea of Marmara and the Black Sea through the Dardanelles in the east. Its surface waters cover 2,969,000 km2, which makes the Mediterranean the largest enclosed sea in the world (Bianchi and Morri, 2000). A recent analysis has estimated the occurrence of some 17,000 marine species in the Mediterranean, with taxa such as the Phaeophyta, Rhodophyta and Porifera including more than 10 per cent of the total number of species known globally (Coll et al., 2010). These figures are remarkable, considering that the Mediterranean Sea covers less than 1 per cent of the surface and volume of the world’s oceans. The origin of the highly diversified Mediterranean biota is relatively recent and is mainly derived from the Atlantic Ocean. The Mediterranean Sea has undergone various geological, climatic and hydrological transformations that have contributed to generate the hotspot of marine biodiversity that we see today (Bianchi and Morri, 2000; Coll et al., 2010; Lejeusne et al., 2010). In particular, isolation from theAtlantic during the Messinian crisis (6 Mya) resulted in strong evaporation with consequent dramatic changes in climate, sea level and salinity (Bianchi and Morri, 2000). The Messinian crisis decimated the biota of the ancient Mediterranean, which was largely dominated by Indo- Pacific species of warm-water affinities. When the connection with the Atlantic was reestablished (5 Mya), the newly colonising species mixed with those surviving the Messinian crisis. Alternating glacial and interglacial periods during the Quaternary, favouring the colonisation of boreal and subtropical species, further contributed to the diversification of the biota in the Mediterranean Sea. The opening of the Suez Canal in 1869 has also impacted on the native biodiversity of the Mediterranean through the introduction of new species from the Red Sea (Galil et al., 2014), which will likely increase in the near future following the expansion of the Suez Canal in 2015 (Galil et al., 2015b). There is a long tradition of descriptive studies in the Mediterranean Sea, with detailed accounts on taxonomic composition and regional patterns of distribution of marine organisms that exploded in the 1960s owing to intensifying oceanographic cruises and the advent of scuba diving (reviewed in Coll et al., 2010). Ourunderstanding of region-wide patterns of marine biodiversity in the Mediterranean Sea has increased considerably in the last fifteen years as a result of large-scale field surveys (Sala et al., 2011), extensive reviews of the literature (Bouillon et al., 2004; Danovaro et al., 2010; Martin and Giannoulaki, 2014; Telesca et al., 2015), modelling (Sarà et al., 2013; Marras et al., 2015) and synthesis of expert opinions (Micheli et al., 2013). This integration has generated new insights into the present distribution of the Mediterranean biota, as well as focussing attention on the main threats to marine biodiversity and the need to implement better conservation practices at the regional scale (Airoldi and Beck, 2007; Claudet and Fraschetti, 2010; Coll et al., 2010, 2012; Mouillot et al., 2011). In contrast to descriptive studies, experimental ecology has only been introduced recently in the Mediterranean, with an initial focus on biological interactions. The first experiment that incorporated the logical requirements of replication, randomisation and independence examined the effect of removing a canopy-forming alga in littoral rock pools (Benedetti-Cecchi and Cinelli, 1992a). A parallel study in the same system expanded the range of species interactions examined to include the effects of herbivory and competition between algal turfs (see Connell et al., 2014, for a clarification of the term turf ) and canopy recruitment (Benedetti-Cecchi and Cinelli, 1992b). Experimental work proliferated in the following years, examining species interactions in the context of ecological succession (Benedetti-Cecchi, 2000a, 2000b) and extending this approach to subtidal environments (Airoldi et al., 1995; Airoldi, 2000a). As we will discuss, some of these studies established the foundation for the theory that canopy-forming algae and turfs represent alternative states in shallow temperate rocky coasts under different disturbance and stress regimes (Airoldi, 1998, 2000b; Benedetti-Cecchi et al., 2001b), and that changes in sediment loads are one of the main triggers of these shifts in subtidal habitats (Airoldi et al., 1996; Airoldi and Cinelli, 1997; Airoldi, 2003; Irving et al., 2009). More recently, manipulations on subtidal rocky reefs have shown how low levels of herbivory in combination with the localincrease of nutrients may foster the recovery of macroalgal canopies and associated biota (Guarnieri et al., 2014). Experiments in the Mediterranean have also contributed to focus attention on the variance of ecological interactions (Benedetti-Cecchi, 2000c, 2003). Novel experimental designs have been developed that facilitate the separation of the effects of changing the mean intensity from the variance of biological interactions or any other spatially or temporally variable ecological process (Bertocci et al., 2005; Benedetti-Cecchi et al., 2006). These experiments revealed, for example, how spatial variance and mean intensity of grazing may interactively maintain spatially heterogeneous patterns of algal cover, illustrating the great potential for grazing to generate alternative states in marine benthic habitats (Benedetti-Cecchi et al., 2005). Motivated by the need to understand the effects of intensifying anthropogenic impacts and climate change on marine biodiversity, an increasing number of studies are now examining species interactions in relation to regional stressors and global threats such as ocean warming, acidification, extreme climate events and biological invasions (Bulleri et al., 2016). A better understanding of biotic interactions in the Anthropocene is also essential to guide habitat rehabilitation and restoration efforts. Here, we provide an overview of this type of research that will likely characterise future experimental research in the Mediterranean and elsewhere, using regime shifts as a conceptual framework to guide this approach. The concept of regime shifts, the abrupt transition between alternative states, unifies key aspects of species interactions and their responses to degrading environmental conditions, including resilience, early warning signals of collapse, extinction and hysteresis, all of which have direct bearing on environmental management. To achieve this, we start with a brief introduction to regime shifts and the underlying theory, followed by a discussion of ongoing regime shifts in the Mediterranean; such as the transition from macroalgal forests to turfdominated assemblages and the widespread collapse of sessile organisms in response to heatwaves, species invasions, infectious diseases andpest metabolites. We then examine the implications of threshold-like biological responses and hysteresis that are typically associated with regime shifts for habitat restoration and rehabilitation. Finally, we conclude with an overview of the research that is needed to understand the interplay between species interactions and rapid environmental change, for which the Mediterranean is providing several dramatic examples.

Habitat-forming species sustain biodiversity and ecosystem functioning in harsh environments through the amelioration of physical stress. Nonetheless, their role in shaping patterns of species distribution under future climate scenarios is generally overlooked. Focusing on coastal systems, we assess how habitat-forming species can influence the ability of stress-sensitive species to exhibit plastic responses, adapt to novel environmental conditions, or track suitable climates. Here, we argue that habitat-former populations could be managed as a nature-based solution against climate-driven loss of biodiversity. Drawing from different ecological and biological disciplines, we identify a series of actions to sustain the resilience of marine habitat-forming species to climate change, as well as their effectiveness and reliability in rescuing stress-sensitive species from increasingly adverse environmental conditions. EuroMarine - European Marine Research Network