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Vermetid reefs are one of the very few reef forming bio-constructions in the entire Mediterranean, supporting rich biodiversity and ecosystem services. Furthermore, they prevent coastal erosion, modulate the transportation of sediments, and act as carbon sinks. Since they build upon fossilized skeletons of the formal reef builder organisms, they are also invaluable assets to study some parameters of paleoclimatology. However, information about their basic features, distribution, and floral and faunal information is not sufficient. Between 2017 and 2019, a study to demonstrate the distributions of the vermetid reefs, biodiversity investigation on selected reefs, and some livelihood evaluation was realized in the 200 km northern coastline of Cyprus. This paper demonstrates the distribution of the reefs with a fish biodiversity analysis recognized by the visual census.

Vermetid reefs are distinctive bioconstructions of the Mediterranean and other warm temperate and subtropical seas. In the Iberian Peninsula the vermetid endemism Dendropoma lebeche Templado et al., 2016 and the coralline alga Neogoniolithon brassica-florida (Harvey) Setchell & Mason are the main biogenic engineers of this natural heritage. However, very few empirical studies deal with their early patterns of succession. We installed two sets of colonization plates in spring (May) and autumn (November) along a healthy vermetid reef on the island Nueva Tabarca (Alicante, SE Iberian Peninsula), to study the early succession patterns of assemblages. Taxonomic composition and the Shannon diversity index were considered over a 1–2 year period. The seasonal month of installation had a detectable effect on taxonomic composition during the first nine months of immersion, also conditioning the diversity pattern. The succession proceeded faster for the May installation set, where both engineering species showed higher cover values from the beginning. Even though there was hardly any three-dimensional accretion on the plates during this study, those that remained well over a year reached Dendropoma densities close to those reported for healthy Mediterranean vermetid reefs. The use of colonization plates as recruitment enhancers could be a potential tool for restoration procedures, because of the minor impact of their installation and the relatively short time required to achieve high vermetid densities. This research received financial assistance from the project “Seguimiento de macroalgas sobre el litoral rocoso y Posidonia de la Comunidad Valenciana, dentro de la Directiva Marco del Agua” of the Generalitat Valenciana.

Vermetid reefs are a key intertidal habitat in the warm-temperate part of the Mediterranean Sea and in some subtropical and tropical regions in the Atlantic and Pacific oceans. This unique and highly diverse ecosystems is under siege due to both the high anthropogenic pressure and the global climate change, with documented local population declines in the Eastern Mediterranean. This study aims at evaluating the conservation state of vermetid reefs along the Lebanese coast (Eastern Mediterranean), where seawater warming, habitat degradation and coastal urbanization likely threaten their presence. In order to assess the conservation status of vermetid reefs in Lebanon, five sites were randomly selected among those belonging to three impact classes: i) not impacted (i.e. protected), ii) moderately impacted, and iii) impacted. Two different non-destructive methods were applied to assess the presence of living vermetids Dendropoma anguliferum (Monterosato, 1878) and Vermetus triquetrus (Bivona-Bernardi, 1832) which shape the reef, and the associated communities. Our results highlight that no living vermetid reefs were recorded in the impacted sites where evident signs of bio-physical erosion of the reef are already underway. Living individuals of Vermetus triquetrus were found in some not impacted and moderately impacted sites, while living individuals of the endemic reef-builder Dendropoma anguliferum were found only at very low densities at the not impacted (protected) site. Such findings corroborate preliminary observations of population decline in the Eastern Mediterranean, and of vermetid reefs vulnerability to human disturbances. This raises concerns about the near future persistence of vermetid reefs in the region, and represents a call for management and conservation actions to preserve this reef-building species in the Mediterranean Sea.

Este artículo contiene 8 páginas, 4 figuras., Experiments have shown that increasing dissolved CO2 concentrations (i.e. Ocean Acidification, OA) in marine ecosystems may act as nutrient for primary producers (e.g. fleshy algae) or a stressor for calcifying species (e.g., coralline algae, corals, molluscs). For the first time, rapid habitat dominance shifts and altered competitive replacement from a reef-forming to a non-reef-forming biogenic habitat were documented over one-year exposure to low pH/high CO2 through a transplant experiment off Vulcano Island CO2 seeps (NE Sicily, Italy). Ocean acidification decreased vermetid reefs complexity via a reduction in the reef-building species density, boosted canopy macroalgae and led to changes in composition, structure and functional diversity of the associated benthic assemblages. OA effects on invertebrate richness and abundance were nonlinear, being maximal at intermediate complexity levels of vermetid reefs and canopy forming algae. Abundance of higher order consumers (e.g. carnivores, suspension feeders) decreased under elevated CO2 levels. Herbivores were non-linearly related to OA conditions, with increasing competitive release only of minor intertidal grazers (e.g. amphipods) under elevated CO2 levels. Our results support the dual role of CO2 (as a stressor and as a resource) in disrupting the state of rocky shore communities, and raise specific concerns about the future of intertidal reef ecosystem under increasing CO2 emissions. We contribute to inform predictions of the complex and nonlinear community effects of OA on biogenic habitats, but at the sametime encourage the use ofmultiple natural CO2 gradients in providing quantitative data on changing community responses to long-term CO2 exposure., This work contributes to the University of Palermo FFR-A project and the EU-FP7 MedSeA project (grant agreement no. 265103) to M.M.

Marine bioconstructions are biodiversity-rich, three-dimensional biogenic structures, regulating key ecological functions of benthic ecosystems worldwide. Tropical coral reefs are outstanding for their beauty, diversity and complexity, but analogous types of bioconstructions are also present in temperate seas. The main bioconstructions in the Mediterranean Sea are represented by coralligenous formations, vermetid reefs, deep-sea cold-water corals, Lithophyllum byssoides trottoirs, coral banks formed by the shallow-water corals Cladocora caespitosa or Astroides calycularis, and sabellariid or serpulid worm reefs. Bioconstructions change the morphological and chemicophysical features of primary substrates and create new habitats for a large variety of organisms, playing pivotal roles in ecosystem functioning. In spite of their importance, Mediterranean bioconstructions have not received the same attention that tropical coral reefs have, and the knowledge of their biology, ecology and distribution is still fragmentary. All existing data about the spatial distribution of Italian bioconstructions have been collected, together with information about their growth patterns, dynamics and connectivity. The degradation of these habitats as a consequence of anthropogenic pressures (pollution, organic enrichment, fishery, coastal development, direct physical disturbance), climate change and the spread of invasive species was also investigated. The study of bioconstructions requires a holistic approach leading to a better understanding of their ecology and the application of more insightful management and conservation measures at basin scale, within ecologically coherent units based on connectivity: the cells of ecosystem functioning.

Vermetid reefs are intertidal biogenic habitats created by a dense aggregation of mollusks, frequently cemented by calcareous algae, and are typical of sub-tropical and warm–temperate rocky shores. These bioconstructions are valuable key-habitats of the coastal zones, increasing their productivity and biological value. In the Mediterranean, the main vermetid reef builders belong to the genus Dendropoma and are associated to encrusting coralline red algae. These organisms are ecosystem engineers protected under international European Legislation, although vermetid reef conservation is limited by a lack of biological and ecological knowledge. The two-way interactions between biota and the physical environment have not been previously studied for these reefs, further limiting understanding of the ecological value and function of this habitat. Phases of the Dendropoma life cycle are also understudied, making the key-processes during the reef development unclear. In an integrated coastal zone management framework, all of this knowledge is fundamental to strengthen vermetid reef conservation and management in the Mediterranean. This thesis aims to further understanding of traits of the Dendropoma reef system, undertaking novel themes of research, and by using an interdisciplinary approach. The research project has two main goals: 1) To describe which contribution the reef provide in preserving rock substrate from physical alteration 2) To understand which cues may promote Dendropoma reef formation A set of laboratory and field experiments and observations has been used to fulfill these aims. The study was conducted in Sicily, central Mediterranean, where the main reef builder species is Dendropoma cristatum (Biondi, 1857), associated with the coralline algae Neogoniolithon brassica-florida (Harvey) Setchell & Mason 1943. In detail, topic 1 aims to describe the bio-protective role of the Dendropoma encrustation on the underneath rock substrate. Bioprotection is described as the contribution that biological layers give to the conservation of the substratum they colonize, by mediating the deteriorative action of other factors, such as physical, chemical and biological weathering. In this study, internal temperature variations and salt weathering have been considered as rock physical stressors that are particularly relevant in the coastal zone, and which may be mediated by the Dendropoma encrustation. Lab experiments and analysis have been employed to describe subsurface variations of temperature and salt content inside rock cores covered by live and dead vermetids vs bare rocks. The experiments have demonstrated that the Dendropoma encrustation exerts a control on the factors responsible for rock weathering. Topic 2 aims to detect which physical and biological factors may promote D. cristatum settlement and recruitment, with implications for the reef development.D. cristatum recruitment and settlement have been measured in the field and in different conditions. A seasonal pattern of recruitment has been described for the Sicilian species D. cristatum, and the hydrodynamic regime has been showed do not affect this pattern within a range of Km. Aside, at a small spatial scale (from mm to cm), biogenic surface have been shown to affect the settlement dynamics of the crawling larvae of Dendropoma cristatum, more than physical complexity of the substratum. In detail, biological cues provided by a layer of crustose coralline algae or by a microbial film, may positively affect settlement dynamic, indicating suitable site for larvae attachment and having an influence on the early stages of Dendropoma cristatum development. In conclusion, this research has contributed to the description of some ecological traits of the reef-builder Dendropomacristatumand provided a wider view of the two-way interactions between this ecosystem engineer and the surrounding physical and biological environment. Within the perspective to improve Dendropoma reef management at Mediterranean scale, the gaining of information about the ecological functioning and role of this coastal systems may provide a valuable contribution. Vermetid reefs are intertidal biogenic habitats created by a dense aggregation of mollusks, frequently cemented by calcareous algae, and are typical of sub-tropical and warm–temperate rocky shores. These bioconstructions are valuable key-habitats of the coastal zones, increasing their productivity and biological value. In the Mediterranean, the main vermetid reef builders belong to the genus Dendropoma and are associated to encrusting coralline red algae. These organisms are ecosystem engineers protected under international European Legislation, although vermetid reef conservation is limited by a lack of biological and ecological knowledge. The two-way interactions between biota and the physical environment have not been previously studied for these reefs, further limiting understanding of the ecological value and function of this habitat. Phases of the Dendropoma life cycle are also understudied, making the key-processes during the reef development unclear. In an integrated coastal zone management framework, all of this knowledge is fundamental to strengthen vermetid reef conservation and management in the Mediterranean. This thesis aims to further understanding of traits of the Dendropoma reef system, undertaking novel themes of research, and by using an interdisciplinary approach. The research project has two main goals: 1) To describe which contribution the reef provide in preserving rock substrate from physical alteration 2) To understand which cues may promote Dendropoma reef formation A set of laboratory and field experiments and observations has been used to fulfill these aims. The study was conducted in Sicily, central Mediterranean, where the main reef builder species is Dendropoma cristatum (Biondi, 1857), associated with the coralline algae Neogoniolithon brassica-florida (Harvey) Setchell & Mason 1943. In detail, topic 1 aims to describe the bio-protective role of the Dendropoma encrustation on the underneath rock substrate. Bioprotection is described as the contribution that biological layers give to the conservation of the substratum they colonize, by mediating the deteriorative action of other factors, such as physical, chemical and biological weathering. In this study, internal temperature variations and salt weathering have been considered as rock physical stressors that are particularly relevant in the coastal zone, and which may be mediated by the Dendropoma encrustation. Lab experiments and analysis have been employed to describe subsurface variations of temperature and salt content inside rock cores covered by live and dead vermetids vs bare rocks. The experiments have demonstrated that the Dendropoma encrustation exerts a control on the factors responsible for rock weathering. Topic 2 aims to detect which physical and biological factors may promote D. cristatum settlement and recruitment, with implications for the reef development.D. cristatum recruitment and settlement have been measured in the field and in different conditions. A seasonal pattern of recruitment has been described for the Sicilian species D. cristatum, and the hydrodynamic regime has been showed do not affect this pattern within a range of Km. Aside, at a small spatial scale (from mm to cm), biogenic surface have been shown to affect the settlement dynamics of the crawling larvae of Dendropoma cristatum, more than physical complexity of the substratum. In detail, biological cues provided by a layer of crustose coralline algae or by a microbial film, may positively affect settlement dynamic, indicating suitable site for larvae attachment and having an influence on the early stages of Dendropoma cristatum development. In conclusion, this research has contributed to the description of some ecological traits of the reef-builder Dendropomacristatumand provided a wider view of the two-way interactions between this ecosystem engineer and the surrounding physical and biological environment. Within the perspective to improve Dendropoma reef management at Mediterranean scale, the gaining of information about the ecological functioning and role of this coastal systems may provide a valuable contribution.

With this study we provide a first baseline assessment of the epifauna associated with the macroalgae of the vermetid reefs present along the coasts of the Island of Favignana (Egadi Islands Marine Protected Area, Italy). A total of 14 taxa were identified. Epifaunal assemblages differed according to structure and composition of algal communities. The amphipod group presented the highest number of individuals. The tubicolous species Ampithoe ramondi Audouin, 1826 (Ampithoidae) was the most abundant species.

Intertidal vermetid reefs are highly diverse systems that provide numerous habitats for animal and vegetal species, leading to an increase of intertidal biodiversity. These habitats, particularly vulnerable to environmental changes and human activities, are now experiencing high mortality in several areas of the Mediterranean Sea. Since alien macroalgae are nowadays considered one of the most serious threats to biodiversity and natural ecosystem functioning, we provide a first baseline assessment of the occurrence of alien species in the vermetid reef along the coasts of the Island of Favignana (Egadi Islands Marine Protected Area). Surveyes carried out in 2015 revealed the only presence of Caulerpa cylindracea Sonder (Bryopsidales, Caulerpaceae). The alga, exclusively recorded within the cuvettes, showed low values of abundance (class 1: cover 20%). No significant correlations were highlighted between the abundance values of C. cylindracea and those of the dominant macroalgae inhabiting the cuvettes.

Vermetid reefs in the Mediterranean Sea are increasingly affected by both anthropogenic actions and global climate change, which are putting this coastal ecosystem at risk. The main species involved in building these reefs are two species of intertidal vermetid gastropods and the crustose calcareous alga, Neogoniolithon brassica-florida, which cements the gastropod shells and thus solidifying the reef edges. In the present study, we examined the pattern of distribution in the field and the environmental sensitivity (thermal tolerance, resilience to low pH, high light intensity and desiccation) of N. brassica-florida along the coasts of Sicily and Israel by means of chlorophyll fluorescence and total alkalinity measurements in situ and in the laboratory. Tidal regimes did not affect photosynthesis of N. brassica-florida but light intensity in the intertidal did. Sensitivity to increased light intensity was amplified by elevated temperature and reduced pH. Winter temperature above 16 °C caused a decrease in the photosynthetic performance of photo-system II. Similarly, a decrease in pH resulted in decreased maximum photosynthetic yield and electron transport rate. Calcification was significantly lower at pH 7.9 as compared with ambient (8.1) pH. In fact, dissolution at pH 7.9 at night was higher than net calcification during the day, suggesting that N. brassica-florida may not be able to contribute to reef accretion under the levels of seawater warming and ocean acidification projected by the end of this century.

Vermetid gastropods are coastal habitat engineers which build biogenic platforms typical of intertidal rocky shores of central and south -east of the Mediterranean. These bioconstructions create a secondary habitat which increases resource availability and space for organisms, locally transforming the environment and modifying coastal geomorphology. Biological characteristics and physical structure of these bioconstructions are commonly studied by field-based sampling. Nevertheless, a lot of time is required to collect data over large areas of reef, field conditions can impair data collection and direct reef image interpretation may be a challenge due to their intertidal position. In this study, a small RPAS is used to describe the macrostructure of two vermetid reefs in different areas: Capo Gallo (NW Sicily) and Favignana Island (W Sicily). 800 m of each reef have been surveyed by using high-resolution aerial orthophotomosaics (2cm/px). Detailed 3D maps have been realized for both reefs and the following measures of ecological relevance have been estimated: external rim length, internal rim length, surface of external rim (mq), cuvette surface (mq) and reef surface (mq). Index of external rim development and Index of internal rim development have been calculated as a relationship between a standardized linear length and the length of the external and internal rim respectively. Total area for Capo Gallo reef is 2563,26 mq; indexes of external and internal rim development are respectively 3,40 and 1,90. For Favignana, reef area is 1263,15 mq and indexes of external and internal rim development are respectively 2,56 and 1,80. These results reveal RPAS as a powerful tool for physical description of vermetid reefs and to calculate how this biogenic habitat shapes the coast and increases habitat complexity on rocky shores. This study, moreover, shows the high potential for RPAS technique to be applied for mapping vermetid reefs and to aid the management and conservation of natural systems, as required by the EU Strategy on Biodiversity which declares the necessity of mapping habitats and the ecosystem services they provide.