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The loss of Mediterranean macroalgal populations dominated by Cystoseira sensu lato is driven by a multitude of pressures. In the eastern Mediterranean Sea, climate change and the establishment of Lessepsian herbivore species have further intensified the ongoing decline of these canopy-forming algae. Knowledge of the reproductive phenology, embryology and growth of Cystoseira species is the first step towards successful reforestation measures. Gongolaria montagnei is one of the most common canopy-forming algal species with a wide horizontal and vertical distribution along the Greek coasts. Mature receptacles were collected from Saronikos Gulf (Aegean Sea), and germlings were cultured in mesocosms for 34 days, reaching up to 1.30 mm in length. Divisions and early developmental stages of G. montagnei are described and possible implications for future restoration efforts are discussed. A new approach to growth rate modeling, based on surface measurements of embryos and germlings is presented.

As a result of several anthropogenic factors, Cystoseira sensu lato forests have declined or become regionally extinct in many coastal regions of the Mediterranean. Given the low natural recovery of lost populations, research efforts have been encouraged to develop sustainable and efficient restoration of macroalgal forests on a large scale. By promoting growth and fertility of collected thallus branches under controlled laboratory conditions, the availability of seedlings for restoration could be ensured without jeopardizing natural populations. Here we investigated the effect of a commercial algal biostimulant (AlgatronCifo®) on the photophysiology, growth and fertility of Gongolaria barbata (Stackhouse) Kuntze (Fucales, Phaeophyceae). In a factorial laboratory experiment, two different temperatures (10 ºC and 14 °C) and two culture media [i.e. seawater (SW) and Algatron (AT)] were tested. The photosynthetic performance of G. barbata doubled after three weeks of culture with AT, while it decreased by 25% when cultivated in SW. The highest photosynthetic performance and growth were achieved at 14ºC with AT, where fertile receptacles also developed, followed by seedling settlements. The thalli cultured in AT had similar or better photosynthetic performance than the initial control thalli. AT-cultured thalli had a greater ability to quench energy via photochemical pathways (qP) than those from the SW, which on the contrary, had higher levels of non-photochemical responses (qN, NPQmax). This limited photosynthetic performance was probably linked to the higher P-limitation experienced under that treatment. The algal biostimulant enhanced the physiological performance and induced fertility of G. barbata, demonstrating its valorization potential and setting a new path for improved restoration applications.

Coastal areas are affected by conflicts between the opportunities and benefits of natural resource exploitation and the preservation of natural ecosystems, as well as by additional stresses and impacts created by ongoing climate change. Coastal infrastructures are one of the major pressures in these areas potentially producing direct and indirect impacts on marine ecosystems. Our pilot project-site is in the area surrounding of the Civitavecchia harbour (Latium, Central Tyrrhenian Sea), whose expansion could affect the existing Posidonia oceanica seagrass meadows, rocky and algal reefs habitats and the conspicuous presence of the giant bivalve Pinna nobilis specimens. In this work we present the RENOVATE project, which aims developing an ecosystem approach to manage and implement compensation and mitigation measures in the coastal marine environment. The project approach is based on the restoration of ecosystem services provided by those natural habitats and sensitive species living near the harbour, as listed before. In order to develop this approach, it is necessary to implement an integrated observing system and operational modelling at regional scale, to contribute to: the development of an early warning system for extreme events, dredging and avoidance of potential impacts; the implementation of ecological compensation measures to restore ecosystem services; the siting and implementation of Nature Based Solutions.

1. The aim of the present study was to propose a biotic index (North Adriatic Mesophotic BiogEnic Reefs, NAMBER) suitable for assessing the ecological quality of the mesophotic biogenic reefs of the northern Adriatic continental shelf based on photographic sampling. 2. At each of the 20 study sites, the degree of bioconstruction (expressed as percentage cover of crustose coralline algae), the α-diversity (expressed as the mean number of taxa), and the degree of sensitivity to human disturbance and climate change (based on literature data and expert judgement) of the benthic assemblages were selected as descriptors and combined in the NAMBER index, using the best values that the three metrics can currently achieve in the studied region as a reference. 3. The study highlighted that there was large spatial heterogeneity among reefs and high variability in the ecological quality values obtained by NAMBER, ranging from bad to high. The index indicates that reefs lying furthest from the coast, under substantially lower anthropogenic pressure, have a generally higher status of environmental quality. However, a clear geographical pattern did not emerge, as reefs close together often had different ecological qualities. 4. The NAMBER index, which combines three ecological descriptors, in accordance with the requirements of the European Marine Strategy Framework Directive, represents a specific adaptation to the northern Adriatic Sea of a multimetric index previously developed for the north-western Mediterranean Sea, capitalizing on previous knowledge and research efforts. 5. This multimetric biotic index provides an effective standardized tool for monitoring programmes and environmental impact assessments in the northern Adriatic mesophotic biogenic reefs and lays the foundation for ecosystem-based management and conservation in this basin.

Brown algae of the genus Cystoseira sensu lato form the most diverse and productive marine ecosystems throughout the Mediterranean Sea and have equal roles also in the Black Sea where they have been decreasing in the recent years. The taxonomy of Cystoseira s.l. taxa from the Black Sea is still not well understood, and questions arise when related taxa have to be delimited. In addition to morphological descriptions, this study provides for the first time molecular data of the Black Sea Cystoseira s.l. distinct morphologies as an additional tool to clarify their identities and phylogenetic affinities. The analysis of two mitochondrial markers (cytochrome oxidase subunit 1—COI, and 23S-tRNAVal intergenic spacer—mt-spacer) showed that Cystoseira s.l. specimens from the Black Sea belong to two recently resurrected genera, namely Gongolaria and Ericaria. Molecular data confirm the morphological identification of G. barbata, which is characterized by high morphological plasticity in the Black Sea. The morphological data presented in this study support the transition of G. barbata to the genus Gongolaria, which was previously proposed based solely on genetic data. For the Black Sea endemic taxon C. bosphorica, sequence divergence suggests conspecificity with Mediterranean Sea species E. crinita and E. barbatula. However, considering original morphological characteristics of the taxon, its geographical isolation, and endemism, the new combination Ericaria crinita f. bosphorica comb. nov. is proposed.

Restoration of foundation species in historical habitat may be difficult if adult facilitation is obligatory for survival of early life stages. 2. On intertidal Mediterranean coasts, large-scale loss of the dominant forest- forming macroalga Ericaria amentacea have prompted restoration efforts using recruits. Yet, early life stages may be more susceptible to the abiotic stress that characterizes their habitat. 3. We tested strategies to enhance resilience of lab-cultured juveniles of E. amen- tacea to environmental stress in historical habitat lacking conspecifics. Juveniles were exposed in culture to fluctuations of the dominant physical stressors, irra- diance and temperature, and then outplanted in upper and lower zones of their native intertidal range. 4. Without adult canopy, juvenile outplant survival was limited to the lower tidal range, with nearly complete mortality in the upper zone. Survival was also strongly determined by spatial clumping of recruits within the outplant sub- strate. Longer-term growth in the lower zone was enhanced by fluctuating mild stress in culture, with variable irradiance and concurrent heat pulses increas- ing post-outplant cover by 40%–60% after 4 months. Clumping also promoted growth across experimental treatments. 5. Synthesis and applications. Reliance on self-facilitation feedbacks is a common barrier to foundation species restoration in high-stress habitats. Our results sug- gest that without adult habitat amelioration, environmental stress limits recruit survival in intertidal algal forest. Yet, exposure to transient, low environmental stress in culture and outplanting of clumped individuals may confer resilience and allow successful establishment of early life stages in zones of reduced abi- otic stress, providing a source for gradual colonization of more high-stress areas.

In the present study, alginate yield and composition were investigated during the seasonal life cycle of the alien brown alga Sargassum muticum harvested from the Atlantic coast of Morocco. Alginate yield ranged from 11.14% in winter to 25.62% in spring/early summer, coinciding with maximum vegetative growth. Monthly monitoring of the alginate block structure showed that the highest mannuronate (M)/guluronate (G) ratio was recorded during the maximum development of S. muticum, before sexual maturity and during resumption of vegetative growth, giving maximum flexibility to the alga. The unusually high molar monad fractions (FG) and dyad fractions (FGG) of guluronic acid in late summer/early autumn appeared to be related to stiffness of senescent thalli. Rheological characterisation showed that the alginate of S. muticum exhibited pseudoplastic behaviour, with the highest apparent viscosities measured in late summer/early autumn when the G blocks dominated the alginate structure. This study suggests that S. muticum could be exploited as an alginophyte for commercial applications. The best harvest time is May-June, which corresponds to the highest alginate yield, maximum thallus growth, and largely completed sexual reproduction, ensuring sustainable exploitation of the species.

Canopy-forming brown algae support highly productive ecosystems whose decline has been attributed to the interplay of several anthropogenic disturbances. Climate change could have disruptive effects on the biology of these species, but the role of temperature in the development of early life stages is poorly understood. The aim of this study was to assess the response of Ericaria giacconei, a winter-reproducing Southern–Mediterranean endemic species, to thermal stress by testing five temperatures (12, 15, 18, 24, and 28°C) on adults and early stages. Chlorophyll a fluorescence of adult plants was measured at 0, 24, 72, and 120 h on nine fronds in each of the three aquaria per treatment. To assess egg release, zygote settlement, and embryo growth rate, approximately 1,200 receptacles were cultured on six Petri dishes per temperature treatment, and 10 random subsections of 2 ×2 mm were examined in three Petri dishes at 0, 20, 44, and 92 h after fertilization. Adult plants showed a plastic physiological response, and thermal stress had no significant effect on PSII efficiency. Embryos fully developed only at 12 and 15°C. Mortality increased at 18 and 24°C, and no zygotes survived at 28°C. In a scenario of further increasing temperatures, the effects of warming could affect the recruitment of E. giacconei and increase its vulnerability to further stresses. These effects on the survival of early stages, which are the bottleneck for the long-term survival of the species, should be taken into account in conservation and restoration measures to maintain canopy-forming macroalgal populations and associated biodiversity and ecosystem services.

Marine Protected Areas (MPAs) are at the core of management and conservation plans aimed at counteracting the ongoing widespread degradation of marine ecosystems. Although the outcomes of protection in enhancing marine biodiversity and restoring populations of exploited species are widely recognized, the putative effect of MPAs in increasing the resilience of marine communities and ecosystems is still underexplored. In this study, long-term data from a no-take area of a Mediterranean MPA and unprotected locations were used to investigate the effects of full protection on the temporal stability of sessile assemblages on shallow subtidal rocky reefs. Results highlighted that assemblages within the no-take area exhibited a more consistent structure over 20 years of study, whereas a significantly larger temporal variability characterized assemblages at the unprotected locations. Reduced levels of human pressure and stabilizing processes related to the re-establishment of the integrity of trophic networks within the MPA could underlie the observed patterns. Assessing whether MPAs may improve the ability of marine communities to absorb disturbance, from local to large scale sources, is essential to ascertain their contribution to future adaptive conservation strategies in the face of global change. This study provided evidence that MPAs, if well managed, can represent an effective tool to smooth fluctuations in the structure of marine communities, thus potentially reducing their vulnerability to natural and human-driven environmental changes.

1. The worldwide decline of marine forests, due to human impacts and climate change, emphasizes the need to develop and implement effective and sustainable solutions to restore these endangered habitats and to re-establish the services they provide. 2. In this study, the ex situ restoration of Treptacantha barbata, a Mediterranean subtidal habitat-forming species of brown seaweed, was for the first time implemented in a marine protected area in the Adriatic Sea. Two restoration efforts were performed in 2019. The first one was started in winter, after a marine heatwave that triggered early fertility, the second one in spring, when the species usually reproduces. 3. This study aimed to evaluate: 1) the disruptive effects of a thermal anomaly on the reproductive biology and performance in culture of T. barbata; and 2) the impact of the grazing pressure on juveniles after the outplanting. 4. The first cultivation was more productive than the second one, in terms of zygote release and germling growth. To mitigate the low efficiency of the second culture and to avoid prolonged highly-demanding maintenance in the mesocosms, the cultivation period was extended outdoors using a structure suspended in the water column. 5. The modular frames conceived for outplanting T. barbata proved to be effective because of their easy operability and low cost. Controlling for herbivorous fish had significant positive effects on both juvenile survival and growth. 6. The outcomes highlighted that an unpredictable climatic event and fish grazing were major threats that impaired the restoration process of T. barbata. These stressors should be considered when developing plans to implement effective large-scale restoration of canopy-forming macroalgae.

In the Mediterranean Sea, marine forests constituted by Cystoseira sensu lato (s.l.) species (Fucales, Phaeophyceae) support highly productive ecosystems, whose decline was ascribed to the interplay of several anthropogenic impacts. Recently, this decline has also been attributed to the increase of seawater temperatures and thermal anomalies, which can alter the reproductive phenology, germling growth and population viability of Cystoseira s.l. species. To manage the conservation of these communities is fundamental to evaluate how current and future foreseen warming scenarios will affect the thermal physiology of different life stages of these species. Moreover, a recognized strategy of management is the identification and protection of contemporary climatic refugia, which may safeguard the persistence of these habitat-forming species. The present research focused on Cystoseira hyblaea Giaccone, which is endemic to the Sicily Channel (Central Mediterranean Sea) and has a narrow distributional range, being only reported in Punta D’Aliga, where it was no longer found, in Cap Bon (Northern Tunisian coast) and in Portopalo di Capo Passero (Sicily, Southern Italy). This species lives in the intertidal and upper sublittoral zone on both semi-exposed and exposed rocky coasts, and its maximum vegetative and reproductive development occurs during winter. Considering the ongoing warming scenario, C. hyblaea could be severely threaten being an intertidal species and due to its cold affinity, the winter reproductive phenology and the restricted distributional range. Therefore, the aim of this study was to assess the thermal tolerance of both embryos and adults of C. hyblaea, in order to evaluate which stage might be the most vulnerable to climate change, and to foresee the possible fate and argue about the future conservation status of this species under a predicted global warming. To perform this research, egg release, zygote settlement, embryo development and adult photosynthetic efficiency were studied, on both early life stages and adults, under five temperature treatments (12, 15, 18, 24, 28 °C) in controlled mesocosms. In particular, ca. 1200 receptacles were cultivated on 6 Petri dishes per temperature treatment. At 0, 20, 44, 92 h after fertilization, 10 random subareas of 2x2 mm were examined in 3 Petri. Chlorophyll a fluorescence of adults was measured at 0, 24, 72, 120 h on 9 fronds in each of the 3 aquaria per treatment. Through the trial, it was observed that the receptacles’ release efficiency did not vary significantly among temperatures. However, the settlement efficiency of C. hyblaea increased from 12 to 18 °C and decreased at 28 °C. Indeed, the extremely low settlement efficiency was at 28 °C, due to the fact that zygotes had undergone lysis because of thermal stress. Regarding the early life stages, embryos showed a complete development only at 12 and 15 °C, while yet at 18 °C mortality increased sharply, being total at 28 °C. In particular, the highest developmental rate was observed at 15 °C (highest percentage of embryos with rhizoids already at 20 h AF), suggesting that this temperature constitutes the thermal optimum for reproduction and development of early developmental stages. On the contrary, adults of C. hyblaea showed a more plastic physiological response and thermal stress did not significantly affect photosynthetic efficiency. The present study demonstrated that adults of C. hyblaea resulted not substantially affected by heat with an expected ability to acclimatise also to elevated temperatures. Contrarily, the early developmental stages resulted strictly stenotherm, requiring a very narrow range of low temperatures for an effective recruitment and development (12-15 °C). Therefore, the recruitment could represent the most vulnerable process to the impacts of climate change in the population dynamics of C. hyblaea. Moreover, the results confirm the cold affinity of this species and suggest that the localities, in which C. hyblaea is confined, are acting as potential climatic refugia. If failure in the recruitment process is reiterated for several years, it will lead to an impoverishment of C. hyblaea populations, ultimately hindering their long-term viability in its current range. Given the fragmented and restricted range and increased frequency of extreme climatic events, C. hyblaea may undergo local extinction. Considering this perspective, the areas in which C. hyblaea manages to survive should receive a higher level of protection. Moreover, this species should be included in the IUCN Red List of Species (IUCN, 2021), being classified as a “Critically endangered” or “Rare”.

The global decline of brown algal forests along rocky coasts is causing an exceptional biodiversity loss. Regardless of conservation efforts, different techniques have been developed for large-scale restoration strategies in the Mediterranean Sea. In this study we tested ex situ pilot restoration of Gongolaria barbata (=Treptacantha barbata) for the first time in Slovenian coastal waters. Healthy apical fronds of the species were collected and the development of recruits on clay tiles was followed under laboratory conditions for 20 days. Despite the experimental difficulties experienced, especially due to the lack of antibiotics to prevent the growth of the biofilm, G. barbata recruits were outplanted in the sea on two concrete plates with 48 tiles each, protected by purpose-built cages to avoid grazing by herbivorous fish. The high survival rate of juveniles after four months in the field (89% of the tiles on the plate that was constantly protected) suggests that outplanting G. barbata is an operable approach for restoration efforts in the northern Adriatic Sea. Our first experiment in Slovenian coastal waters provides new information for the optimization of the best practices during the laboratory cultivation and addresses the early steps of restoration and introduction of young thalli in the natural environment.

High complexity habitat traits (i.e. high heterogeneity and/or size of discrete habitat units) often promote larger abundances of fauna. Sandy and rhodolith sea bottoms are typically interspersed as mosaics within coastal landscapes. The aim of this study was to experimentally assess the effect of two complexity attributes of rhodolith nodules (i.e. their heterogeneity and size) on the abundance and structure of vagile epibenthic assemblages. An early-colonization experiment was set up (July 2016), where experimental units containing rhodolith nodules of varying heterogeneity and size were deployed at two adjacent recipient habitats: a sandy bottom and a rhodolith seabed. After one month, the abundance of fauna colonizing the experimental units was similar in both habitats, but the assemblage structure (i.e. composition) notably differed. Importantly, the heterogeneity, rather than the size, of experimental rhodolith nodules influenced patterns of vagile macrofauna (>0.5 mm) colonization, despite the habitat type where these experimental units were deployed considerably influenced colonization patterns. This result reinforces the idea of the importance of rhodolith tri-dimensional structure, as key influencer on faunal communities of nearshore habitats.

Rhodolith beds (RBs) are bioconstructions characterized by coralline algae, which provide habitat for several associated species. Mediterranean RBs are usually located in the mesophotic zone (below 40 m), and thus are frequently remote and unexplored. Recently, the importance and vulnerability of these habitats have been recognized by the European Community and more attention has been drawn to their investigation and conservation. This study reports the results of an extensive monitoring program, carried out within the Marine Strategy Framework Directive (2008/56/EC), in six sites off the Campania coast (Italy, Mediterranean Sea). New insights were given into the distribution, cover, vitality (i.e., live/dead rhodolith ratio), structural complexity, and coralline algae composition of RBs. Remotely operated vehicles (ROV) investigations allowed the description of several RBs, and the discovery of a RB with rhodolith cover &gt, 65% offshore the Capri Island. Only two sites (Secchitiello and Punta Campanella) showed a very low mean cover of live rhodoliths (&lt, 10%), hence, not being classifiable as RBs. The collected rhodoliths were mostly small pralines (~2 cm), spheroidal to ellipsoidal, with growth-forms ranging from encrusting/warty to fruticose/lumpy. Coralline algae identification revealed a high diversity within each bed, with a total of 13 identified taxa. The genus Lithothamnion dominated all sites, and Phymatolithon calcareum and Lithothamnion corallioides, protected by the Habitats Directive (92/43/EEC), were detected in all RBs.

International audience; Lithophyllum species in the Mediterranean Sea function as algal bioconstructors, contributing to the formation of biogenic habitats such as coralligenous concretions. In such habitats, thalli of Lithophyllum, consisting of crusts or lamellae with entire or lobed margins, have been variously referred to as either one species, L. stictiforme, or two species, L. stictiforme and L. cabiochiae, in the recent literature. We investigated species diversity and phylogenetic relationships in these algae by sequencing three markers (psbA and rbcL genes, cox2,3 spacer), in conjunction with methods for algorithmic delimitation of species (ABGD and GMYC). Mediterranean subtidal Lithophyllum belong to a well‐supported lineage, hereby called the L. stictiforme complex, which also includes two species described from the Atlantic, L. lobatum and L. searlesii. Our results indicate that the L. stictiforme complex consists of at least 13 species. Among the Mediterranean species, some are widely distributed and span most of the western and central Mediterranean, whereas others appear to be restricted to specific localities. These patterns are interpreted as possibly resulting from allopatric speciation events that took place during the Messinian Salinity Crisis and subsequent glacial periods. A partial rbcL sequence from the lectotype of L. stictiforme unambiguously indicates that this name applies to the most common subtidal Lithophyllum in the central Mediterranean. We agree with recent treatments that considered L. cabiochiae and L. stictiforme conspecific. The diversity of Lithophyllum in Mediterranean coralligenous habitats has been substantially underestimated, and future work on these and other Mediterranean corallines should use identifications based on DNA sequences.

Rhodolith beds represent a key habitat worldwide, from tropical to polar ecosystems. Despite this habitat is considered a hotspot of biodiversity, providing a suite of ecosystem goods and services, still scarce quantitative information is available thus far about rhodolith beds occurrence and ecological role, especially in the Mediterranean Sea. This study reports the composition and patterns of distribution of rhodolith assemblages found in four study areas along ca. 860 km of coast in the Central Mediterranean Sea. These rhodolith beds were studied for the first time and significant differences at all spatial scales have been highlighted, documenting the high variability of this habitat. Rhodolith species composition, morphology and distribution have been discussed considering the potential role of environmental factors in driving these patterns. The need for improving their protection is discussed to complement present conservation and management initiatives, particularly in the frame of the EU Marine Strategy Framework Directive.

Anthropogenic impacts and rapid environmental changes are causing unpredictable shifts in Mediterranean canopy‐forming brown algae, leading to their regression or loss. Thus, there is an urgent need to set standards and guidelines to optimize the restoration, in order to grant the persistence of marine forests in the future. Out‐planting represents an innovative technique for restoring Fucales, although its implementation consists of a set of delicate steps (Falace et al. 2018, De La Fuente et al. 2019), which need to be tailored to the specific requirements of the target species.Here, we report the results gathered both in the Ligurian Sea and the Gulf of Trieste during the first two years of the EU project ROCPopLife. The two sites are subject to different regimes of human impact (being the Ligurian site in a good environmental status, while the Adriatic site in an urbanized context), but both experienced abrupt and extreme climate events. In the Ligurian Sea, in July 2018 clay tiles with Cystoseira amentacea var. stricta Montagne germlings (~3 mm) were screwed to the rocky shore. After 2 months in the field, over the 40% of the tiles were covered with juveniles of ca. 8 mm. However, 6 months after the tile deployment, an unprecedented storm surge severely affected the restoration performance, leading to the loss of the 80% of the tiles. The remaining tiles hosted 3 to 6 cm‐long juveniles, which reached 6‐9 cm in length after 1 year. In the Gulf of Trieste, a heatwave of 2.65 °C in February 2019 caused a premature reproductive event in Treptacantha barbata (Stackhouse) S. Orellana & M. Sansón, so that the species was found fertile almost 3 months earlier than usual (Bevilacqua et al. 2019). This anomalous event was exploited for carrying out a restoration event, and the same procedure was carried out in May. However, the number of released zygotes was 10 times lower and the germling length after 4 weeks of culture was ¼ with respect to the previous anomalous event. Once in the field, half of the tiles from the February event were protected against herbivores; starting from the fourth week, length was significantly lower in unprotected tiles, and, after 3 months, the 36% of the unprotected tiles resulted empty because of grazing effects. Since both predictable site‐specific stressors and anomalous climatic events can severely affect the restoration actions, the challenge is now to optimize the restoration process (from the monitoring of the donor populations to that of outplants) in order to overcome the negative effects of unpredictable impacts.

The resilience of ecological communities is often defined by one or a few species that have disproportionately important roles influencing many other species in the community. This is true for some areas of the Mediterranean Sea that are characterized by large brown fucoid algae in the genus Cystoseira that form dense underwater forests structurally similar to the giant kelps of the Pacific. While shorter than the giant kelp, Cystoseira form dense underwater stands, contributing to the three‐dimensional complexity of the seascape (Fig. 1). These canopy‐forming seaweeds play a crucial role in primary production and nutrient cycling of temperate coastal ecosystems from the Mediterranean Sea to the Atlantic Ocean (Mineur et al., 2015) and act as ‘ecosystem engineers', providing food, nursery, and shelter for a rich associated biota. Our study highlighted potential disruptive effects of winter hot spells on reproductive timing, recruitment, and adult survival that could severely affect the persistence of Cystoseira populations. Because extreme climate episodes are increasing in intensity and frequency, implementing coordinated initiatives connecting centers for climate alerts and algologists may shed light on how these phenomena impact population dynamics of Cystoseira species, and help current attempts to restore algal forests.

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.

Fucus virsoides is an ecologically important canopy-forming brown algae endemic to the Adriatic Sea. Once widespread in marine coastal areas, this species underwent a rapid population decline and is now confined to small residual areas. Although the reasons behind this progressive disappearance are still a matter of debate, F. virsoides may suffer, like other macroalgae, from the potential toxic effects of glyphosate-based herbicides. Here, through a transcriptomic approach, we investigate the molecular basis of the high susceptibility of this species to glyphosate solution, previously observed at the morphological and eco-physiological levels. By simulating runoff event in a factorial experiment, we exposed F. virsoides to glyphosate (Roundup® 2.0), either alone or in association with nutrient enrichment, highlighting significant alterations of gene expression profiles that were already visible after three days of exposure. In particular, glyphosate exposure determined the near-complete expression shutdown of several genes involved in photosynthesis, protein synthesis and stress response molecular pathways. Curiously, these detrimental effects were partially mitigated by nutrient supplementation, which may explain the survival of relict population in confined areas with high nutrient inputs. Our results show that glyphosate impairs the expression of genes involved in photosynthesis and protein synthesis in F. virsoides.

Connectivity is a fundamental ecological property affecting stability, resilience and recovery of marine populations, in particular in networks of patchy habitats as the Mesophotic Biogenic Habitats of the Northern Adriatic Sea. Specific information on the dispersal behaviour of many species living in these habitats is lacking, thus the connectivity simulations were performed over different pelagic propagules duration and different reproductive seasons of six consecutive years, covering most of the possible dispersal behaviour variability. The connectivity simulations were analysed with graph analysis methods by characterizing each connectivity graph with several structural measures and by identifying sites with greatest individual and group centrality. We tested the hypothesis that geographic proximity of sites cannot be a proxy for the connectivity and that hydrodynamic connectivity is statistically significantly related to the observed beta diversity among the studied sites. Results showed that species with different pelagic propagules duration follow greatly different dispersal dynamics, and that the network of studied outcrops is only partially connected to coastal benthic populations. Our results also made possible a critical appraisal of the current conservation strategies, evidencing gaps in the existing network of protected Mesophotic Biogenic Habitats in the Northern Adriatic Sea. We suggest possible improvements for an efficient preservation strategy of these unique biodiversity hotspots by including a fundamental ecological process, the dispersal connectivity, into the process of decision making for conservation.

Glyphosate, as a broad-spectrum herbicide, is frequently detected in water and several studies have investigated its effects on several freshwater aquatic organisms. Yet, only few investigations have been performed on marine macroalgae. Here, we studied both the metabolomics responses and the effect on primary production in the endemic brown algae Fucus virsoides exposed to different concentration (0, 0.5, 1.5 and 2.5 mg L−1) of a commercial glyphosate-based herbicide, namely Roundup®. Our results show that Roundup® significantly reduced quantum yield of photosynthesis (Fv/Fm) and caused alteration in the metabolomic profiles of exposed thalli compared to controls. Together with the decrease in the aromatic amino acids (phenylalanine and tyrosine), an increase in shikimate content was detected. The branched-amino acids differently varied according to levels of herbicide exposure, as well as observed for the content of choline, formate, glucose, malonate and fumarate. Our results suggest that marine primary producers could be largely affected by the agricultural land use, this asking for further studies addressing the ecosystem-level effects of glyphosate-based herbicides in coastal waters.

Structure and spatial variability of coralligenous assemblages of the Apulian continental shelf in the southern Adriatic Sea were investigated. The area consists of small coralligenous outcrops distributed between 30 and 100 m of depth on coarse detritic or muddy bottom. Photographic samples, obtained through a Remotely Operated Vehicle, were analyzed to evaluate the abundance of the main taxa or morphological groups of macroalgae and sessile invertebrates, and the deposited sediment. A multifactorial sampling design was used to compare assemblages at two depth ranges, the shallow outcrops (between 35 and 45 m) and the deep outcrops (between 60 and 70 m), and to determine the main scales of spatial variation. Assemblages were dominated by encrusting and erect sponges, encrusting and filamentous algae, scleractinians, encrusting and erect bryozoans and the Zoantharia Parazoanthus axinellae. Deep assemblages were characterized by lower alpha and beta diversity, and by the decrease or disappearance of sensitive organisms, such as coralline macroalgae, scleractinians and erect bryozoans, and by the dominance of encrusting sponges, P. axinellae and hydrozoans. Sedimentation was higher on deep outcrops and was suggested to be the main driver of differences between shallow and deep assemblages. The peculiar composition of assemblages found in the Apulian continental shelf provides evidence that these outcrops represent an uncommon coralligenous habitat.

Carpodesmia barbatula (= Cystoseira barbatula) (Fucales, Phaeophyta) is a species endemic to the Southern Mediterranean Sea, which grows in clean waters on exposed sublittoral rocky shores. Together with other species of the genus Cystoseira sensu lato, it is an ecosystem engineer that forms dense canopy forests, sustaining biodiversity, productivity and nutrient cycling in temperate rocky reefs. Human impacts and climate stressors are seriously hampering these ecosystems and actual conservation efforts appear insufficient for their preservation. Restoration actions could be a solution for the loss of these habitats, but they require the deep knowledge of the target species. In the present study, we describe egg release, zygote development and germling growth of C. barbatula, poorly known, despite its importance in the upper sublittoral seaweed flora. The aim is to improve the knowledge on the early life stages of this rare and threatened species, towards its possible future restoration.

In the Mediterranean Sea, brown algae belonging to the Cystoseira genus play a valuable role as foundation species. Due to evidences of regression/loss of the habitats of these species caused by the interplay of human and climatic disturbances, active restoration measures have been encouraged by EU regulations. In particular, nondestructive restoration techniques, which avoid the depletion of threatened species in donor populations, are strongly recommended. In the framework of the EU project ROCPOP-Life, the first ex situ outplanting experience of Cystoseira amentacea var. stricta has been implemented in the Cinque Terre Marine Protected Area (northwestern Mediterranean). A total of 400 clay tiles, hosting approximately three mm-long germlings of C. amentacea, were fixed to the rocky shore with screws: the tiles were monitored for the next 2 months by photographic sampling, and survival (presence/absence of juveniles on the tiles), cover and growth were assessed. Additional sampling was performed 6 months after tile deployment, after which an unprecedented storm surge severely affected the restoration performance. After 2 months, over 40% of the tiles were covered with Cystoseira juveniles, which reached approximately eight mm in total length. The tiles that survived the storm hosted three to six cm-long juveniles. The high cover (≥25%), assuring moisture and shading, and the appropriate size of the juveniles, to avert micro-grazing, at time of deployment were key to the survival and growth of the outplanted juveniles, increasing the potential for restoration success. Our findings show that outplanting of midlittoral canopy-forming species is a feasible approach for restoration efforts, with particular attention given to the early phases: (i) laboratory culture, (ii) transport, and (iii) juvenile densities. These results are strongly encouraging for the implementation of restoration actions for C. amentacea on a large scale, in light of EU guidelines.

Herbicides are increasingly recognised as sources of water pollution. Glyphosate-based herbicides (GBHs) are widely used because of their low cost and high effectiveness. By measuring the photosynthetic efficiency of Fucus virsoides fronds exposed to a GBH (Roundup® Power 2.0), we investigated the effect of a continuous exposure (6 days) and the potential of recovery after a short exposure (24 h). Both experiments were carried out combining GBH with and without nutrient enrichment, simulating a runoff event. A factorial experimental design allowed us to assess the potential of interactions between GBH and nutrients, which are likely to co-occur in coastal areas. Our results show deleterious effects of GBH at low concentration on F. virsoides, independently from the duration of exposure and the presence of nutrients. The use of herbicides on land might represent an underestimated threat for coastal systems, as suggested by the irreversible impact on the macroalgae Fucus virsoides observed after a short experimental exposure to a common glyphosate-based herbicide

Protocols for Macroalgae Research describes state-of-the-art approaches and applications in seaweed research. The book is comprised of 31 protocols in all and provides critical information regarding the cultivation and preservation of seaweeds, their chemical composition, as well as their cellular and molecular characterization. This type of research is critical and timely, as the last few decades have witnessed remarkable advancements in phycological research worldwide. Consideration of algal resources for food, fuel, chemicals, feed, and fertilizer has furthered the development of diverse laboratory techniques that not only advance their utilization substantially, but also provided new insights in understanding the molecular basis of their form and function. This recent progress has enabled researchers to determine and quantify various metabolites and organic macromolecules such as carbohydrates, proteins, and lipids. Protocols for Macroalgae Research thus uses macroalgae as a model organism for addressing fundamental research problems. No recent comprehensive literature of this format exists on this topic. As such, this state-of-the-art protocol text both develops and standardizes the various macroalgae approaches located within the field. It does so by featuring a wide-range of protocols from invited experts; each protocol features a brief introductory overview, an inventory of materials and reagents, and step-by-step experimental procedures, which include helpful notes offering care and cautions. This protocol book is an invaluable reference for beginning and preexisting researchers within the field of macroalgae.

Due to multiple impacts, Cystoseira forests are experiencing a significant decline, which is affecting the ecosystem services they provide. Despite conservation efforts, there is an urgent need to develop best practices and large-scale restoration strategies. To implement restoration actions, we developed an ex situ protocol for the cultivation of Cystoseira. amentacea var. stricta, aimed at reducing the time needed for laboratory culture, thus avoiding prolonged maintenance and minimizing costs. Specifically, we tested the effects of temperature, light and substratum on settlement and growth of early life stages using a factorial experiment. Temperature (20 and 24°C) and photoperiod (15L:9D) were selected to reflect the conditions experienced in the field during the reproductive period. Two light intensities (125 and 250 μmol photons m-2s-1) were selected to mimic the condition experienced in the absence of canopy (i.e. barren-higher light intensity) or in the understory (lower light intensity) during gamete release. The tested substrata were flat polished pebbles and rough clay tiles. The release of gametes and the successive survival and development of embryo and germlings were followed for two weeks. Regardless of the culture conditions, rougher tiles showed higher zygote settlement, but the substrata did not affect the successive development. Zygote mortality after one week averaged 50% and at the end of the second week, embryonic survival was higher under lower light and temperature conditions, which also determined the growth of larger embryos.

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.

One of the objectives of the BALMAS project was to conduct Port Baseline Biological Surveys of native and non-indigenous benthic flora in 12 Adriatic ports. Samples of macroalgae growing on vertical artificial substrates were collected in spring and autumn 2014 and/or 2015. A total number of 248 taxa, 152 Rhodophyta, 62 Chlorophyta, and 34 Ochrophyta, were identified. Of these, 13 were non-indigenous seaweeds, mainly filamentous macroalgae, that were probably introduced through hull fouling. Some of these taxa had already been described in the study areas, others were recorded for the first time, a few were no longer detected at sites where they had previously been recorded (e.g. Sargassum muticum). Some other NISS reported for the Adriatic Sea, were not collected at any sampling site (i.e. Caulerpa cylindracea, Codium fragile). Possible reasons for the absence of these species are discussed.

Phymatolithon lamii (Hapalidiaceae, Corallinales, Rhodophyta) is reported for the first time in the Mediterranean Sea. A morphological-anatomical account of Gulf of Trieste specimens is presented along with comparisons with P. lamii specimens from other regions, comparisons with other Mediterranean species of Phymatolithon and a dichotomous key to known Mediterranean species of Phymatolithon. Whether P. lamii occurs naturally in the Mediterranean Sea but was previously misidentified as P. lenormandii or is, alternatively, an alien species, or both, has not been resolved.

In the framework of the WFD 2000/60/EC intercalibration process the updated versions of the EEI and R-MaQI, proposed by Italy and Greece for the transitional waters, have been applied to the macrophytes of the Venice lagoon to test their comparability and relationships with the pressure gradients. Submerged macrophytes were collected during spring 2007 at 60 sites spread within the lagoon. At each site, five random samples were collected and the total coverage of benthic macrophytes in the field was estimated based on a number of tests of the bottom. To assess seagrass epiphytes, five shoots were collected for each replicate. Physico-chemical data were collected in the water column at 14 sites selected to reflect the main hydro-geomorphological and trophic gradients of the lagoon. The analyses performed indicated that the two metrics appeared to be weakly intercalibrated and only the 30% of the sampling sites displayed the same quality class. The main differences fell into the Moderate and Low classes and the two indices provided discordant results in the intermediate and confined areas of the lagoon. In contrast, the two indices showed good affinity in the marine areas of inlets, which are characterised by seagrass meadows and late-successional macroalgae. Similar results were evidenced also in a redundancy analysis by the different relationships between quality classes and the physico-chemical gradients. The main reason for this seems to be the heterogeneity of species–environment relationships inside the groups of species on which the indices are based. Critical aspects of methodological differences and applicability of the macrophyte indices proposed by Italy and Greece for the transitional waters of the Mediterranean eco-region are discussed.

The coralline red alga Mesophyllum (Hapalidiaceae) is recorded for the first time from the Gulf of Trieste (Northern Adriatic Sea) and gametangial plants of M. macroblastum are recorded for the first time from the Mediterranean Sea. A morphological-anatomical account is provided, including comparisons with specimens from the western coast of Italy and with published data. Distribution and habitat information, comparison with Mediterranean species of Mesophyllum, and a dichotomous key to Mediterranean species are included along with brief comments on other species in the genus known to produce volcano-like tetrasporangial conceptacles.

This article gives an up-to-date review of the status of and main changes in benthic algal flora that have occurred in recent decades along the Italian Adriatic coastline. Common traits among the main structural/functional changes observed and their causes are discussed. A synthesis of the challenges to and prospects of filling gaps in the data, ecological knowledge and protection measures are also given.

Lithophyllum byssoides is a comm on coralline alga in the intertidal zone of Mediterranean coasts, where it produces biogenic concretions housing a high algal and invertebrate biodiversity. This species is an ecosystem engineer and is considered a target for conservation efforts, but designing effective conservation strategies currently is impossible due to lack of information abo ut its population structure. The morphological and molecular variation of L. byssoides was investigated using morphoanatomy and DNA sequences (psbA and cox2,3) obtained from populations at 15 localities on the Italian and Croatian coasts. Lithophyllum byssoides exhibited a high number of haplotypes (31 psbA haplotypes and 24 cox2,3 haplotypes) in the central Mediterranean. The psbA and cox2,3 phylogenies were congruent and showed seven lineages. For most of these clades, the distribution was limited to one or a few localities, but one of them (clade 7) was widespread across the central Mediterranean, spanning the main biogeographic boundaries recognized in this area. The central Mediterranean populations formed a lineage separate from Atlantic samples; psbA pairwise divergences suggested that recognition of Atlantic and Mediterranean L. byssoides as different species may be appropriate. The central Mediterranean haplotype patterns of L. byssoides were interpreted as resulting from past climatic events in the hydrogeological history of the Mediterranean Sea. The high haplotype diversity and the restricted spatial distribution of the seven lineages suggest that individual populations should be managed as independent units.