Rapid Biodiversity Assessment and Monitoring Method for Highly Diverse Benthic Communities: A Case Study of Mediterranean Coralligenous Outcrops

Increasing anthropogenic pressures urge enhanced knowledge and understanding of the current state of marine biodiversity. This baseline information is pivotal to explore present trends, detect future modifications and propose adequate management actions for marine ecosystems. Coralligenous outcrops are a highly diverse and structurally complex deep-water habitat faced with major threats in the Mediterranean Sea. Despite its ecological, aesthetic and economic value, coralligenous biodiversity patterns are still poorly understood. There is currently no single sampling method that has been demonstrated to be sufficiently representative to ensure adequate community assessment and monitoring in this habitat. Therefore, we propose a rapid non-destructive protocol for biodiversity assessment and monitoring of coralligenous outcrops providing good estimates of its structure and species composition, based on photographic sampling and the determination of presence/absence of macrobenthic species. We used an extensive photographic survey, covering several spatial scales (100s of m to 100s of km) within the NW Mediterranean and including 2 different coralligenous assemblages: Paramuricea clavata (PCA) and Corallium rubrum assemblage (CRA). This approach allowed us to determine the minimal sampling area for each assemblage (5000 cm2 for PCA and 2500 cm2 for CRA). In addition, we conclude that 3 replicates provide an optimal sampling effort in order to maximize the species number and to assess the main biodiversity patterns of studied assemblages in variability studies requiring replicates. We contend that the proposed sampling approach provides a valuable tool for management and conservation planning, monitoring and research programs focused on coralligenous outcrops, potentially also applicable in other benthic ecosystems

The yellow gorgonian Eunicella cavolini: demography and disturbance levels across the Mediterranean Sea

The yellow octocoral Eunicella cavolini is one of the most common gorgonians thriving in Mediterranean hard-bottom communities. However, information regarding its distribution and ecology in several parts of the Mediterranean is lacking, while population trends and conservation status remain largely unknown. We investigated 19 populations of E. cavolini over three representative geographic regions: the NW Mediterranean, CE Adriatic, and N Aegean. Focusing on the upper bathymetric range of the species (30 cm). The CE Adriatic displayed intermediate densities, with well-structured populations, and continuous recruitment. In the N Aegean, most populations presented low densities, high proportion of large colonies, but low number of small colonies, signifying limited recruitment. Disturbance levels, as a function of extent and type of injury, are discussed in relation to past or present human-induced threats. This work represents geographically the most wide ranging demographic study of a Mediterranean octocoral to date. The quantitative information obtained provides a basis for future monitoring at a Mediterranean scale

Re-shifting the ecological baseline for the overexploited Mediterranean red coral

Overexploitation leads to the ecological extinction of many oceanic species. The depletion of historical abundances of large animals, such as whales and sea turtles, is well known. However, the magnitude of the historical overfishing of exploited invertebrates is unclear. The lack of rigorous baseline data limits the implementation of efficient management and conservation plans in the marine realm. The precious Mediterranean red coral Corallium rubrum has been intensively exploited since antiquity for its use in jewellery. It shows dramatic signs of overexploitation, with no untouched populations known in shallow waters. Here, we report the discovery of an exceptional red coral population from a previously unexplored shallow underwater cave in Corsica (France) harbouring the largest biomass (by more than 100-fold) reported to date in the Mediterranean. Our findings challenge current assumptions on the pristine state of this emblematic species. Our results suggest that, before intense exploitation, red coral lived in relatively high-density populations with a large proportion of centuries-old colonies, even at very shallow depths. We call for the re-evaluation of the baseline for red coral and question the sustainability of the exploitation of a species that is still common but ecologically (functionally) extinct and in a trajectory of further decline

Overview of the conservation status of Mediterranean anthozoans

The IUCN Red List of Threatened SpeciesTM – Regional AssessmentThis report presents the conservation status of the anthozoans occurring in the Mediterranean Sea, based on the assessment of 136 species using the IUCN Red List methodology. It identifies those species that are threatened with extinction at the regional level to guide appropriate conservation actions in order to improve their statusVersión del edito

Habitat features and their influence on the restoration potential of marine habitats in Europe

To understand the restoration potential of degraded habitats, it is important to know the key processes and habitat features that allow for recovery after disturbance. As part of the EU (Horizon 2020) funded MERCES project, a group of European experts compiled and assessed current knowledge, from both past and ongoing restoration efforts, within the Mediterranean Sea, the Baltic Sea, and the North-East Atlantic Ocean. The aim was to provide an expert judgment of how different habitat features could impact restoration success and enhance the recovery of marine habitats. A set of biological and ecological features (i.e., life-history traits, population connectivity, spatial distribution, structural complexity, and the potential for regime shifts) were identified and scored according to their contribution to the successful accomplishment of habitat restoration for five habitats: seagrass meadows, kelp forests, Cystoseira macroalgal beds, coralligenous assemblages and cold-water coral habitats. The expert group concluded that most of the kelp forests features facilitate successful restoration, while the features for the coralligenous assemblages and the cold-water coral habitat did not promote successful restoration. For the other habitats the conclusions were much more variable. The lack of knowledge on the relationship between acting pressures and resulting changes in the ecological state of habitats is a major challenge for implementing restoration actions. This paper provides an overview of essential features that can affect restoration success in marine habitats of key importance for valuable ecosystem services

Recruitment Disruption and the Role of Unaffected Populations for Potential Recovery After the Pinna nobilis Mass Mortality Event

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.En prens

Current marine pressures and mechanisms driving changes in marine habitats

Human activities and the resultant pressures they place on the marine environment have been widely demonstrated to contribute to habitat degradation, therefore, their identification and quantification is an essential step towards any meaningful restoration effort. The overall scope of MERCES Deliverable 1.2 is to review current knowledge regarding the major marine pressures placed upon marine ecosystems in EU waters and the mechanisms by which they impact habitats in order to determine potential restoration pathways. An understanding of their geographical distribution is critical for any local assessment of degradation, as well as for planning conservation and restoration actions. This information would ideally be in the form of maps, which: (a) compile single or multiple activities and pressures over broad scales, integrating and visualizing available data and allowing direct identification of aggregations as well as gaps and (b) may be overlaid with habitat maps (or any other map layer containing additional information), thus combining different data levels and producing new information to be used for example when implementing EU policies. The deliverable also documents typical example habitat case studies, the prominent impacts and consequences of activities and pressures towards the identification of possible restoration or mitigation actions. Finally the deliverable discusses pressures, assessments, marine spatial planning and blue growth potential. Activities and pressures are used in a strict sense, where marine activities are undertaken to satisfy the needs of societal drivers (e.g. aquaculture or tourism) and pressures are considered to be the mechanism through which an activity has an actual or potential effect on any part of the ecosystem (e.g. for demersal trawling activity, one pressure would be abrasion of the seabed). Habitats are addressed using a nested approach from large-scale geological features (e.g. shallow soft bottoms) to species-characterised habitats (e.g. Posidonia meadows) because of the way they are referred to in current policy documents which lack standard and precise definitions

Mimicry of emergent traits amplifies coastal restoration success

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Where Is More Important Than How in Coastal and Marine Ecosystems Restoration

Restoration is considered an effective strategy to accelerate the recovery of biological communities at local scale. However, the effects of restoration actions in the marine ecosystems are still unpredictable.We performed a global analysis of published literature to identify the factors increasing the probability of restoration success in coastal and marine systems. Our results confirm that the majority of active restoration initiatives are still concentrated in the northern hemisphere and that most of information gathered from restoration efforts derives from a relatively small subset of species. The analysis also indicates that many studies are still experimental in nature, covering small spatial and temporal scales. Despite the limits of assessing restoration effectiveness in absence of a standardized definition of success, the context (degree of human impact, ecosystem type, habitat) of where the restoration activity is undertaken is of greater relevance to a successful outcome than how (method) the restoration is carried out. Contrary to expectations, we found that restoration is not necessarily more successful closer to protected areas (PA) and in areas of moderate human impact. This result can be motivated by the limits in assessing the success of interventions and by the tendency of selecting areas in more obvious need of restoration, where the potential of actively restoring a degraded site is more evident. Restoration sites prioritization considering human uses and conservation status present in the region is of vital importance to obtain the intended outcomes and galvanize further actions

Human activities and resultant pressures on key European marine habitats: An analysis of mapped resources

Human activities exert a wide range of pressures on marine ecosystems, often resulting in the loss of species and degradation of habitats. If effective policies and management practices to restore past damage and reduce future impacts to the marine environment are to be developed, knowledge of the extent, duration and severity of activities and pressures is essential, yet often lacking. As part of the EU H2020 project “Marine Ecosystem Restoration in Changing European Seas”, this study uses an exhaustive review of published records, web resources, and grey literature to comprehensively assess the degree to which human activities and pressures are mapped within European seas. The results highlight a number of limitations and gaps, including: (a) limited geographic coverage at both the regional and sub-regional level; (b) insufficient spatial resolution and accuracy in recorded data for the planning of conservation and restoration actions; (c) a lack of access to the background data and metadata upon which maps are based, thus limiting the potential for synthesis of multiple data sources. Based on the findings, several recommendations for future marine research initiatives arise, most importantly the need for coordinated, geographically extended baseline assessments of the distribution and intensity of human activities and pressures, complying with high-level standardization regarding methodological approaches and the treatment of produced data