Biodiversity loss in a Mediterranean ecosystem due to an extreme warming event unveils the role of an engineering gorgonian species

Stochastic perturbations can trigger major ecosystem shifts. Marine systems have been severely affected in recent years by mass mortality events related to positive thermal anomalies. Although the immediate effects in the species demography affected by mortality events are well known, information on the mid- to long-term effects at the community level is much less documented. Here, we show how an extreme warming event replaces a structurally complex habitat, dominated by long-lived species, by a simplified habitat (lower species diversity and richness) dominated by turf-forming species. On the basis of a study involving the experimental manipulation of the presence of the gorgonian Paramuricea clavata, we observed that its presence mitigated the effects of warming by maintaining the original assemblage dominated by macroinvertebrates and delaying the proliferation and spread of the invasive alga Caulerpa cylindracea. However, due to the increase of sediment and turf-forming species after the mortality event we hypothesize a further degradation of the whole assemblage as both factors decrease the recruitment of P.clavata, decrease the survival of encrusting coralligenous-dwelling macroinvertebrates and facilitate the spreading of C. cylindracea

Local-scale climatic refugia offer sanctuary for a habitat-forming species during a marine heatwave

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A decision-support framework for the restoration of Cystoseira sensu lato forests

Macroalgal forests characterised by species of the genus Cystoseira sensu lato form important shallow coastal rocky habitats in the Mediterranean Sea. These forests support a high biodiversity and provide important ecosystem services and societal benefits. Currently these habitats are often in a poor condition in many areas, due to loss and degradation from both anthropogenic and climate stressors. Restoration has recently moved to the forefront of the United Nations and European Union agendas to reverse this trend, particularly in the last decade with the implementation of various international policies. However, this has been in the form of generic targets (e.g., restoration of 30% of degraded habitats by 2030) and has not been linked to specifically what habitat or species to restore, where and how. Initial targets have been missed, new targets are expected through the proposed EU Nature Restoration Law, but overall guidance is still lacking. There are few specific guides to marine habitat restoration limited to mostly seagrass, corals and shellfish. As a priority action for the recovery of coastal marine ecosystems a decision-support framework has been developed for the restoration of Mediterranean macroalgal forests, comprising a stepwise decision tree with additional descriptions of key elements to be considered for a restoration action. The decision tree includes steps concerning current and historical forest presence, site local condition assessment and choice of actions. Key considerations include restoration implementation (competence, society and support, finance and governance), success evaluation (at the target species and the ecosystem level) and long-term management. The framework builds on existing work on Cystoseira s.l. restoration, the work carried out in the EU AFRIMED project, but also on principles and guidelines in place for both generic and specific marine habitats. The work reported here has involved the expertise of scientists and information from stakeholders. Gaps were identified and recommendations were made, dealing with stressors, coordinating and networking stakeholders, integrating top down policy and bottom up initiatives, funding of restoration actions, establishing synergies between restoration, conservation and marine spatial planning and finally communication and publicity

Unpublished Mediterranean records of marine alien and cryptogenic species

Good datasets of geo-referenced records of alien species are a prerequisite for assessing the spatio-temporal dynamics of biological invasions, their invasive potential, and the magnitude of their impacts. However, with the exception of first records on a country level or wider regions, observations of species presence tend to remain unpublished, buried in scattered repositories or in the personal databases of experts. Through an initiative to collect, harmonize and make such unpublished data for marine alien and cryptogenic species in the Mediterranean Sea available, a large dataset comprising 5376 records was created. It includes records of 239 alien or cryptogenic taxa (192 Animalia, 24 Plantae, 23 Chromista) from 19 countries surrounding the Mediterranean Sea. In terms of records, the most reported Phyla in descending order were Chordata, Mollusca, Chlorophyta, Arthropoda, and Rhodophyta. The most recorded species was Caulerpa cylindracea, followed by Siganus luridus, Magallana sp. (cf. gigas or angulata) and Pterois miles. The dataset includes records from 1972 to 2020, with the highest number of records observed in 2018. Among the records of the dataset, Dictyota acutiloba is a first record for the Mediterranean Sea. Nine first country records are also included: the alga Caulerpa taxifolia var. distichophylla, the cube boxfish Ostracion cubicus, and the cleaner shrimp Urocaridella pulchella from Israel; the sponge Paraleucilla magna from Libya and Slovenia; the lumpfish Cyclopterus lumpus from Cyprus; the bryozoan Celleporaria vermiformis and the polychaetes Prionospio depauperata and Notomastus aberans from Malta

Unpublished Mediterranean and Black Sea records of marine alien, cryptogenic, and neonative species

To enrich spatio-temporal information on the distribution of alien, cryptogenic, and neonative species in the Mediterranean and the Black Sea, a collective effort by 173 marine scientists was made to provide unpublished records and make them open access to the scientific community. Through this effort, we collected and harmonized a dataset of 12,649 records. It includes 247 taxa, of which 217 are Animalia, 25 Plantae and 5 Chromista, from 23 countries surrounding the Mediterranean and the Black Sea. Chordata was the most abundant taxonomic group, followed by Arthropoda, Mollusca, and Annelida. In terms of species records, Siganus luridus, Siganus rivulatus, Saurida lessepsianus, Pterois miles, Upeneus moluccensis, Charybdis (Archias) longicollis, and Caulerpa cylindracea were the most numerous. The temporal distribution of the records ranges from 1973 to 2022, with 44% of the records in 2020–2021. Lethrinus borbonicus is reported for the first time in the Mediterranean Sea, while Pomatoschistus quagga, Caulerpa cylindracea, Grateloupia turuturu, and Misophria pallida are first records for the Black Sea; Kapraunia schneideri is recorded for the second time in the Mediterranean and for the first time in Israel; Prionospio depauperata and Pseudonereis anomala are reported for the first time from the Sea of Marmara. Many first country records are also included, namely: Amathia verticillata (Montenegro), Ampithoe valida (Italy), Antithamnion amphigeneum (Greece), Clavelina oblonga (Tunisia and Slovenia), Dendostrea cf. folium (Syria), Epinephelus fasciatus (Tunisia), Ganonema farinosum (Montenegro), Macrorhynchia philippina (Tunisia), Marenzelleria neglecta (Romania), Paratapes textilis (Tunisia), and Botrylloides diegensis (Tunisia).peer-reviewe

Biodiversity loss in a Mediterranean ecosystem due to an extreme warming event unveils the role of an engineering gorgonian species

Abstract Stochastic perturbations can trigger major ecosystem shifts. Marine systems have been severely affected in recent years by mass mortality events related to positive thermal anomalies. Although the immediate effects in the species demography affected by mortality events are well known, information on the mid- to long-term effects at the community level is much less documented. Here, we show how an extreme warming event replaces a structurally complex habitat, dominated by long-lived species, by a simplified habitat (lower species diversity and richness) dominated by turf-forming species. On the basis of a study involving the experimental manipulation of the presence of the gorgonian Paramuricea clavata, we observed that its presence mitigated the effects of warming by maintaining the original assemblage dominated by macroinvertebrates and delaying the proliferation and spread of the invasive alga Caulerpa cylindracea. However, due to the increase of sediment and turf-forming species after the mortality event we hypothesize a further degradation of the whole assemblage as both factors decrease the recruitment of P.clavata, decrease the survival of encrusting coralligenous-dwelling macroinvertebrates and facilitate the spreading of C. cylindracea

Restoration of a Canopy-Forming Alga Based on Recruitment Enhancement: Methods and Long-Term Success Assessment

Marine forests dominated by macroalgae have experienced noticeable regression along some temperate and subpolar rocky shores. Along continuously disturbed shores, where natural recovery is extremely difficult, these forests are often permanently replaced by less structured assemblages. Thus, implementation of an active restoration plan emerges as an option to ensure their conservation. To date, active transplantation of individuals from natural and healthy populations has been proposed as a prime vehicle for restoring habitat-forming species. However, given the threatened and critical conservation status of many populations, less invasive techniques are required. Some authors have experimentally explored the applicability of several non-destructive techniques based on recruitment enhancement for macroalgae restoration; however, these techniques have not been effectively applied to restore forest-forming fucoids. Here, for the first time, we successfully restored four populations of Cystoseira barbata (i.e., they established self-maintaining populations of roughly 25 m2 ) in areas from which they had completely disappeared at least 50 years ago using recruitment-enhancement techniques. We compared the feasibility and costs of active macroalgal restoration by means of in situ (wild-collected zygotes and recruits) and ex situ (provisioning of lab-cultured recruits) techniques. Mid/long-term monitoring of the restored and reference populations allowed us to define the best indicators of success for the different restoration phases. After 6 years, the densities and size structure distributions of the restored populations were similar and comparable to those of the natural reference populations. However, the costs of the in situ recruitment technique were considerably lower than those of the ex situ technique. The restoration method, monitoring and success indicators proposed here may have applicability for other macroalgal species, especially those that produce rapidly sinking zygotes. Recruitment enhancement should become an essential tool for preserving Cystoseira forests and their associated biodiversity

Effects of climate change on the red gorgonian Paramuricea clavata and the associated coraligen in the national maritime-terrestrial park of the archipelago de Cabrera

Linares, Cristina ... et. al.-- 23 pages, 10 figures, 7 tables[EN] Climate change is impairing ecosystems around the world. The assessment of the ecological responses of marine ecosystems within the ongoing environmental change is pivotal for conservation of our natural heritage and for a proper management of marine protected areas. Among marine Mediterranean habitats, coralligenous assemblages are highly diverse and exhibit a great structural complexity. In some sectors of the Archipelago of Cabrera National Park, there is an exceptional coralligenous habitat dominated by the red gorgonian Paramuricea clavata. The main goal of the project was to describe the thermal regime of this environment and to study the effects and consequences of thermal anomalies related to climate change over P. clavata and the associated coralligenous assemblages as well as to evaluate the recover capacity of the gorgonian populations. Two positive thermal anomalies detected in 2007 and 2011 sharply affected the studied coralligenous habitat, and specially the red gorgonians. Our monitoring shows a generalized loss of gorgonians at the shallowest depth range of distribution of the species (between 35 and 45 depth), while the colonies living at deeper waters were hardly affected. These thermal anomalies also affected other species associated to the coralligenous habitat, being tunicates and cnidarians the most affected. Experiments performed in aquaria showed contrasting thermal tolerance thresholds among the most representative coralligenous species, which helps to explain the changes observed at the community level in the field. Field experiments demonstrate that P. clavata has an important structural role in coralligenous outcrops, although its presence does not mitigate neither the impact of thermal anomalies on the species present in the understory assemblage nor the invasion of the coralligenous habitat by alien algae. This study shows important changes in the structure of benthic habitats associated to climate change, with loss of habitat complexity and negative effects on the associated biodiversity[ES] El cambio global afecta a la biodiversidad. Conocer las respuestas de los hábitats a este nuevo contexto ambiental es uno de los retos más importantes para la conservación. El coralígeno es un hábitat mediterráneo emblemático caracterizado por albergar una gran biodiversidad y ser muy vulnerable al cambio global. En sectores muy concretos del Parque Nacional Marítimo-Terrestre del Archipiélago de Cabrera se desarrolla un extraordinario coralígeno dominado por la gorgonia roja (Paramuricea clavata). El objetivo principal de este proyecto ha sido caracterizar el régimen térmico de la zona y estudiar los efectos y las consecuencias del cambio climático sobre P. clavata y el coralígeno asociado, así como evaluar su capacidad de recuperación. Dos eventos de mortalidad masiva de la gorgonia roja afectaron gravemente al coralígeno dominado por esta especie. Estas mortalidades están relacionadas con fuertes anomalías térmicas positivas (2007 y 2011). El seguimiento realizado muestra claramente la pérdida casi total de las gorgonias en el rango más somero de su distribución inicial (entre 35 y 45 m de profundidad) mientras que las colonias más profundas (por debajo de los 45 metros) han resultado menos afectadas. Dichas anomalías térmicas también han tenido efectos significativos en el resto de la comunidad del coralígeno, viéndose muy afectadas algunas especies de tunicados y cnidarios. Experimentos realizados en acuarios con las especies más representativas del coralígeno han mostrado diferentes umbrales de termotolerancia, lo que ayuda a explicar los cambios a nivel de comunidad observados en el campo. Experimentos in situ también demuestran el rol estructural de la gorgonia P. clavata, aunque ésta no contribuye de forma significativa a la resistencia del resto de especies del coralígeno frente a los efectos del cambio climático y a la invasión del coralígeno por algas exóticasEste trabajo se ha beneficiado de la financiación de los proyectos «Efectos del cambio global sobre la biodiversidad marina del Parque Nacional de Cabrera: el caso de la comunidad del coralígeno de Paramuricea clavata» financiado por la Fundación Biodiversidad (2008-2010) y «Respuesta de la comunidad del coralígeno del Parque Nacional de Cabrera al cambio climático» financiado por el OAPN (2012-2016)Peer Reviewe

State of knowledge on key eco-evolutionary processes and factors driving the resilience of the shallow hard bottoms and mesophotic habitats

The main goal of Deliverable 3.1. is to synthetize the information available on key eco-evolutionary processes and factors to guide the development of novel and efficient restoration actions to be planned, developed and performed within WP3. We focused on macroalgae and mesophotic coralligenous habitats since i) there are increasing evidences of relevant changes and lost of these two habitats across the whole Europe and ii) they are featured by the presence of species that are considered critical for the functioning of the coastal marine systems. In addition, these habitats display contrasted characteristics in terms of dominant groups (macroalgal species vs. macroinvertebrate), driving processes (trophic interactions-physical factors vs. competition), dynamics (fast vs. low turnover) and environmental conditions (shallow-light vs. deep-dim light habitats). [...]Grant agreement n. 689518Peer Reviewe