Rocky Coasts Research Articles

Late Quaternary uplift and sea level fluctuations along the Tyrrhenian margin of Basilicata - northern Calabria (southern Italy): New constraints from raised paleoshorelines

New analyses of marine terraces in the Tyrrhenian Sea margin of Basilicata - northern Calabria (southern Italy) have been carried out. In the study area, c. 25 km in length, an impressive flight of marine terraces occurs, with the highest terraces reaching ~160 m a.s.l. Detailed geomorphological-stratigraphical analyses on remnants of paleoshorelines located within 60 m a.s.l. have shown that the rocky coast of the investigated coastal stretch has been affected by multiple relative sea-level fluctuations, during which reworking of older shorelines has occurred. Dating of the coral Cladocora caespitosa and speleothems, either predating or postdating single paleoshorelines, has allowed the construction of a chronological framework for the identified relative sea-level markers, and their correlation with MIS 7, MIS 6e and distinct peaks of MIS 5. A mean uplift rate of c. 0.25 mm/y since the Last Interglacial has been quantified, one order of magnitude larger than previous estimates. The uplift rate value has been used to infer the elevations of MIS 5a, 5c and 6e sea level peaks, which are higher than those reported in most sea level curves worldwide, although consistent with several findings from the western Mediterranean. Our results demonstrate that a mere sequential correlation may be misleading in the interpretation of flights of marine terraces and indicates that multiple age controls are crucial to unravelling the complex interaction between uplift and sea-level fluctuations in uplifted coastal areas. The reconstructed MIS 5a, 5c and 6e sea level paleo-elevations, besides contributing to the assessment of late Quaternary sea-level fluctuations in the Mediterranean Sea, may contribute to constrain coeval ice sheets volume variations.

Interplay Between Coastal Elevation and Wave Height Controls the Occurrence of Coastal Boulder Deposits in the Aran Islands, Ireland

Coastal boulder deposits (CBD) are wave-emplaced supratidal accumulations that record extreme inundation on rocky coasts. They are poorly understood but are of growing importance as we seek to better understand the extremes of wave power on coastlines. The Aran Islands, Ireland, host CBD in varying settings ranging from sheer cliff tops to wide shore platforms, and at elevations to about 40 m above sea level. Deposits are known to be active during strong storm events and provide a unique opportunity to examine relationships between wave energy, setting, and CBD occurrence. We use topographic elevation (Z) and offshore 100-years significant wave height (Hs,100) to calculate a dimensionless elevation Z* = Z/Hs,100 at 25 m intervals all along the Atlantic-facing coasts of the Aran Islands, and record whether CBD were present or absent at each location. The data reveal universal CBD presence at locations with low dimensionless elevations and near-monotonic decreasing frequency of CBD occurrence as Z* increases. On the Aran Islands, CBD are restricted to locations with Z*<3.13. For high elevation deposits it appears that unresolved local factors may be the major determinants in whether CBD will form. This approach can be applied at any CBD-bearing coastline and has the potential to change the way that we think about these deposits. Evaluation of dimensionless elevations at CBD locations around the world will help build broader understanding of the impact local shoreline conditions have on CBD formation. Determining these relationships contributes to the ongoing need to better understand interactions between extreme waves and rocky coasts.

Pathological conditions of the sentinel bivalve, the little mussel Brachidontes rodriguezii, from contaminated intertidal sites in the Southwestern Atlantic coast

A survey of pathological conditions affecting the natural beds of the dominant bivalve species of the intertidal rocky coasts of the Southern Atlantic Ocean, was performed. Samples of the little mussel (n = 992), Brachidontes rodriguezii, which is considered a sentinel species, were collected from seven sites that present different anthropogenic activity (low anthropogenic activity, harbor, and sewage waste) along the Argentinean coast, and processed by standard histological techniques. Our results showed for the first time in a B. rodriguezii population from Mar del Plata harbor a bacterium causing cellular lysis of the spermatogenic cells (6.5% of prevalence) and in a population from Villa Gesell, a site with low anthropogenic activity, one little mussel presented cytoplasmic vacuoles in the oocytes’s cytoplasm similar to a microsporidian (0.2% of prevalence). A ciliated protozoan parasitizing the cytoplasm of the epithelial digestive tubules and larval stages of two different digenean parasites, was found infecting the little mussel from both contaminated and uncontaminated sites. Sporocysts of the family Bucephalidae invaded the gonad, causing severe gonadal damage including castration, and gymnophallid metacercariae located between the mantle and shell or embedded in the mantle tissues, occupied the gonadal space.In Punta Carballido, a site located next to a sewage outfall, the highest prevalence of infection was found, for the ciliated protozoan in the digestive tubules (5.1%) and for the digenean parasites (bucephalid sporocyst 24.4%, and gymnophallid metacercariae 50%). Moreover, we found a positive correlation between shell length and overall prevalence of parasites.

Morphological identification of crabs in the rocky coast of Manado Bay

Coastal areas have a wealth of biological natural resources including marine life such as crustaceans. One of the marine organisms in the crustacean group is the crab. The purpose of this study was to identify the types of crabs that live in rocky coastal habitats through a morphological approach. To determine the morphology of crabs can be done by looking at the shape, color, and size. The results of this study found 3 types of crabs in two locations in the Manado Bay area including the crab is Grapsus albolineatus, Ozius truncatus, and Uca (Galasimus) tetragonon. Based on the results of the research above, morphological forms were found on the abdomen in the form of a tapered triangle which indicated that the crab was male and the abdomen was triangular with the female sex. The most common crabs found at the study site were female crabs.Keywords: Coastal Area; Crab; Morphology AbstrakWilayah pesisir memiliki kekayaan sumber daya alam hayati diantaranya biota laut seperti krustasea. Salah satu organisme laut dalam golongan krustasea adalah kepiting. Tujuan dari penelitian ini adalah untuk mengidentifikasi jenis kepiting yang hidup di habitat pantai pesisir berbatu melalui pendekatan morfologi. Untuk mengetahui morfologi pada kepiting dapat dilakukan dengan melihat bentuk, warna serta ukuran. Hasil penelitian ini menemukan 3 jenis spesies kepiting pada dua lokasi yang berada di daerah Teluk Manado diantaranya kepiting Grapsus albolineatus Ozius truncatus dan Uca (Galasimus) tetragonon. Berdasarkan hasil penelitian diatas maka ditemukan bentuk morfologis pada bagian abdomen berbentuk segitiga meruncing yang menunjukkan bahwa kepiting tersebut berkelamin jantan dan abdomen berbentuk segitiga melebar merupakan kepiting dengan jenis kelamin betina. Kepiting yang paling banyak ditemukan pada lokasi penelitian adalah kepiting betina. Kata Kunci: Wilayah Pesisir; Kepiting; Morfologi

Sentinel-1 Data Processing for Detecting and Monitoring of Ground Instabilities in the Rocky Coast of Central Asturias (N Spain)

The cliff coastline of the central region of Asturias (N Spain) is severely affected by terrain instabilities, causing considerable damage to properties and infrastructures every year. In this study, we applied the A-DInSAR technique based on Sentinel-1 imagery to map and monitor active slopes in an emblematic rocky area of the Asturian coast: the Peñas Cape. The A-DInSAR dataset analysis has been focused at regional and local scales. For the local scale assessment, six areas were selected based on previous work and the landslide database of the Principality of Asturias region (BAPA-Base de datos de Argayos del Principado de Asturias), created by the University of Oviedo. The processing of the data has been performed using two independent sets of processing tools: the PSIG software tools, a professional tool and, the GEP service, an unsupervised platform. The dataset consisted of 113 SAR IW-SLC images acquired by the Sentinel-1 A/B satellites between January 2018 and February 2020. LOS mean deformation velocity maps (mm year−1) and deformation time series (mm) were obtained by PSIG and GEP software, allowing coastal areas with landslide incidence and other terrain movements to be distinguished. Deformation motion has been estimated from PSIG VLOS rates to be from −17.1 to 37.4 mm year−1 and GEP VLOS rates from −23.0–38.3 mm year−1. According to deformation time series (mm), the minimum and maximum accumulated displacements are −68.5–78.8 and −48.8–77.0 mm by means of PSIG and GEP, respectively. These ground motions could be associated with coastal instabilities related to marine activity and coastal retreat, both at regional and local study scales. The main contributions of this work are: (1) the demonstration of the potential of A-DInSAR techniques to evaluate coastal instabilities in a coastal retreat context and (2) the comparison of the results provided by the two sets of tools, which allowed the ground motion to be assessed by using an unsupervised approach vs. a contrasted one (robust software). This study increases the knowledge about coastal instabilities and other ground movements along the rocky coast and cliffs of Central Asturias. As a conclusion for the future, we believe that this work highlights the evaluated methods as significant tools to support the management of coastal territories with jagged and rocky coastlines.

Mapping of Coastline Changes in Athens Riviera over the Past 76 Year’s Measurements

Mapping of coastline changes assists in coastal development and monitoring. Athens Riviera, located in the southwestern coastal zone in Attica in central Greece, has undergone major and radical changes generated by human interference during the last decades. The aim of this paper is to map record and measure the coastline changes in Athens Riviera over the past 76 years. Aerial photographs and satellite images from 1945 to 2021 as well as geographic information system (GIS) techniques were used to depict the spatial and temporal variations of the coastline. The results show that 60% of the total length of the coastline is artificial coast, while 29% is rocky coast and 12% beach. The study of seven subareas showed that human interventions caused significant coastline changes in Faliro Bay, Alimos and Glyfada. The adjacent coastal regions to Athens metropolitan area illustrate the highest modifications in the coastline. The main changes in the coastlines are recorded from 1960 to 1987, while the rate of changes in coastline slowed down from 1987 to 2021. The total changes in the coastline of Athens Riviera demonstrate that, during the past 76 years, the coastline was enhanced by 40% while land reclaimed to the sea area approaches 2.67 km2. The applied method is effective and rapid and may utilize in the coastal monitoring and management.

Sentinel-1 Data Processing for Detecting and Monitoring of Ground Instabilities in the Rocky Coast of Central Asturias (N Spain)

Sentinel-1 Data Processing for Detecting and Monitoring of Ground Instabilities in the Rocky Coast of Central Asturias (N Spain)

Sea squirt invaders

Invasive Species Invasive marine species can be aggressive ecosystem engineers, dramatically altering new habitats by overgrowing preexisting species and threatening coastal ecology. Pyura praeputialis , an intertidal tunicate indigenous to the southeastern coast of Australia, invaded the coastline of Chile a few hundred years ago. The species is present, so far exclusively, along 70 kilometers of rocky coast inside the Bay of Antofagasta, where it has become ecologically dominant. Hudson et al. combined species distribution models and genomic data to understand the invasion history of this tunicate and what potential habitats might be available adjacent to its current introduced range. Although animals from a single region of eastern Australia contributed to the colonization of the Bay of Antofagasta, the population shows high genomic diversity and considerable adaptive potential. The authors identified more than 3500 kilometers of coast along the eastern Pacific at potential risk of invasion. Slight changes in currents and human-assisted contamination could help the spread of this damaging sea squirt. Proc. Natl. Acad. Sci. U.S.A. 118 , e2022169118 (2021).

Coastal morphology and heavy mineral accumulation in an upper-macrotidal environment – A geological-mineralogical approach from source to trap site in a natural placer laboratory (Channel Islands, Great Britain)

The Isles of Jersey and Guernsey, GB, are situated in the Bight of St. Malo which ranks among the upper-macrotidal environments with one of the highest tidal ranges ever measured on the globe. They are built up of metasedimentary and –magmatic basement rocks followed by a suite of gabbro-diorite-granite intrusive rocks. Based on sedimentological, geomorphological and mineralogical investigations focused on heavy minerals (HM) the coastal environment has been subdivided into three principal coastal types headland-, headland-bay and bay types. Chemical and physical weathering, neotectonics, eustatic sea level changes, wave action, land-derived sediment supply and aeolian processes had not only a strong impact on the various coastal landform series (CLFS) established but also on the variegated HM assemblages casting them into the role of markers for the coastal environment and some kind of an ore guide for marine placer deposits. Tidal-dominated coastal environments under study sculptured exclusively out of crystalline bedrocks are conservative with regard to the economic geology and potential of HM placer-type deposits provided while physical weathering predominates over the chemical one. The tidal processes in context with the other land-forming processes are special importance for the diversity of coastal features within the environment hosting HM on a small- and large-scale. Neotectonics may accentuated or suppress tidally-controlled features in that strong uplift and provokes typical tidal features to get suppressed so that vast tidal flats are missing in a great deal of coastal areas and rocky coasts formed instead with consequences for the accumulation of HM. The “GMS tool (granulometry-morphology-situmetry) has methodologically proved to be very effective for the study of the coastal zones hosting HM in two principal ways. Granulometric and the morphological variation of HM can successfully be used for the host rock environment analysis (“ore guide”). Morphometric studies and situmetric measurements of gravel clasts in the coastal sediments bearing HM accompanied by similar measurement of joints and faults cutting through the bedrock can assist in the localization of HM trap sites in shoreline platforms and their rock veneer. The HM associations in upper-macrotidal environments are variegated in terms of morphology, mineralogical composition and their geomorphological trap sites so that they constitute a natural laboratory for environment analysis in terms of hydrodynamic and (paleo) climate along marine terrigenous shorelines and help better understand the way of HM from source to trap site in modern and paleoplacers.

Lithostratigraphy, microfacies and paleogeography of the shallow marine Middle Limestone Member of the Early Eocene Rusayl Formation, Oman: Relationship to the Early Eocene Climatic Optimum, sea-level changes and regional uplift

We logged five outcrops of the Middle Limestone Member (MLM) of the Early Eocene Rusayl Formation. The eastern sections contain more, much coarser and also more angular detritus than the western sections. Moreover, notable concentrations of red algae, gastropods, corals, oysters and echinoids only occur in the eastern sections. Benthic foraminifers are typical for the entire MLM, but in the west, they are more abundant (dominated by miliolids). Peloids are restricted to the western sections. While the western sections display a subtidal lagoonal facies, capped by thin intertidal deposits, the coarse clastic material of the eastern sections indicates the proximity of a mountainous paleocoast with a resulting rocky coast environment. The coarse eastern facies proves that the Saih Hatat Dome as part of the Oman Mountains had already emerged while the MLM accumulated. Because of the differences, no outcrop correlations between the western and eastern sections are possible. However, facies boundary correlations among the western sections are feasible, spanning a distance of 23.5 km. Among the eastern sections, basal coarse clastics as well as two bioclastic marker horizons were correlated over 26 km. Deposition of the MLM was favored by high temperatures during the Early Eocene Climatic Optimum (EECO) at 53-51 Ma and a correspondingly high eustatic sea-level. The presence of corals in proximity of a mountainous, rocky paleocoast indicates dry conditions (clear water) during the EECO. The final shallowing-up observed in the west is attributed to the end of the EECO when mean global temperatures and the eustatic sea-level dropped. Shallowing from subtidal to intertidal conditions restricted parts of the lagoon and caused evaporation/hypersaline conditions as indicated by monospecific small miliolids and also by early dolomitization due to Mg-rich brines (reflux model). The western sections show signs of dolomitization. The Al-Khod section is the first one to be reported to be intensely dolomitized.

The Application of UAV for the Analysis of Geological Hazard in Krk Island, Croatia, Mediterranean Sea

The coastal area around the settlement of Stara Baška (Krk Island, NE channel zone of Adriatic Sea) is in a delicate geodynamic balance. The main causes are the geological structure, hydrological and hydrogeological conditions and the direct exposure of the coast to the waves and storm surges. In this paper, the effects of the expected sea level rise on the geological vulnerability of the coast are investigated. Detailed field research was conducted. The complex coastal morphology was surveyed using an Uncrewed Aerial Vehicle (UAV), and the UAV-derived data was used as a 3D point cloud and orthophoto for analysis. In the investigated coastal zone, more resistant Quaternary talus breccias predominate over more susceptible flysch rock mass. One major and two smaller landslides are in a creeping condition and pose a hazard to the surrounding homes. During storm surges, the pocket beaches are completely inundated due to the narrow beach width and waves reach the toe of the slopes. According to the expected sea level rise, coastal processes could become more intense and threaten the current coastal equilibrium. The vulnerability of a large part of the Stara Baška settlement will increase significantly. The conducted research showed the advantages of UAV-derived data for the study of complex rocky coasts and emphasized the need for repeatable UAV surveys.

우주선유발 동위원소를 이용한 한반도 암석해안 발달과 침식에 대한 수치모형연구: 서해안 둔두리 파식대, 동해안 독도 파식대를 사례로

기후변화와 인간 간섭으로 인해 해안의 범람과 침식 위험도가 증가하여 해안 침식 연구의 필요성이 증대되고 있다. 본 연구에서는 서해안 둔두리 파식대와 동해안 독도 파식대를 따라 나타나는 우주선유발 동위원소의 농도 분포를 이용한 수치 모형을 통해 장기간 평균 해안 후퇴율을 모의하고, 해식애 후퇴-파식대 발달시기를 추정하고자 하였다. 이론적으로 지난 홀로세 해수면 상승시기 동안 형성된 파식대의 경우 파식대를 따라 동위원소 농도 분포가 혹 형태로 나타나며, 현재 파식대 일부가 지난 간빙기로부터 유전되었을 경우, 과거 해식애 위치에서 농도가 급증하는 계단 형태를 보인다. 또한 해식애 후퇴율이 빠르면 동위원소 농도는 낮게, 후퇴율이 느리면 농도는 높게 나타난다. 모의 결과, 둔두리 파식대는 72-150 m 구간에서 동위원소 농도가 홀로세 구간 평균의 11배 높게 나타나 파식대의 일부가 지난 간빙기에 유전된 것이라고 추정되며, 산정된 해식애 후퇴율은 약 0.6-12 mm/yr이다. 반면, 독도 파식대의 경우 농도가 급증하는 구간이 없어, 홀로세 해수면 상승시기 동안에만 형성된 것으로 추정되며, 산정된 후퇴율은 60<SUB>-30</SUB><SUP>+140</SUP> mm/yr이다.

Primary and Secondary Environmental Effects Triggered by the 30 October 2020, Mw = 7.0, Samos (Eastern Aegean Sea, Greece) Earthquake Based on Post-Event Field Surveys and InSAR Analysis

On 30 October 2020, an Mw = 7.0 earthquake struck the eastern Aegean Sea. It triggered earthquake environmental effects (EEEs) on Samos Island detected by field surveys, relevant questionnaires, and Interferometric Synthetic Aperture Radar (InSAR) analysis. The primary EEEs detected in the field comprise coseismic uplift imprinted on rocky coasts and port facilities around Samos and coseismic surface ruptures in northern Samos. The secondary EEEs were mainly observed in northern Samos and include slope failures, liquefaction, hydrological anomalies, and ground cracks. With the contribution of the InSAR, subsidence was detected and slope movements were also identified in inaccessible areas. Moreover, the type of the surface deformation detected by InSAR is qualitatively identical to field observations. As regards the EEE distribution, effects were generated in all fault blocks. By applying the Environmental Seismic Intensity (ESI-07) scale, the maximum intensities were observed in northern Samos. Based on the results from the applied methods, it is suggested that the northern and northwestern parts of Samos constitute an almost 30-km-long coseismic deformation zone characterized by extensive primary and secondary EEEs. The surface projection of the causative offshore northern Samos fault points to this zone, indicating a depth–surface connection and revealing a significant role in the rupture propagation.

Challenges and new strategies in assessing multidecadal shore platform sandy beach evolution from aerial imagery

The world's coastlines are dominated by rocky coasts, where embayed and shore platform beaches develop. The intrinsic characteristics of these environments make them extremely vulnerable to changes in oceanographic forcing. Assessing long-term beach evolution can be a challenging task because coastline indicators were developed for wide and low-lying sandy beaches. For example, as most shore platforms beaches are limited by a cliff or structure, they have a static landward boundary (coastline), thus inhibiting the use of any coastline indicator as a proxy of beach volume changes. Also, as shoreline position is highly dependent on short-term sea-level fluctuations, the use of shoreline indicators is frequently subject to high uncertainty.This work presents an unconventional way to evaluate shore platform beach evolution by proposing a new indicator - the beach toe (BT) - to assess changes in sand retention for shore platform/perched beaches. BT position, together with a profile model, provide an effective tool to assess beach volume over time.The proposed beach indicator was tested at 12 shore platform beaches located at Cascais coast (Portugal), which can be considered illustrative of this type of beach.Results show that the new approach provides an objective indicator to assess both the beach configuration and changes in volume, being easily implemented using common vertical imagery. The comparison of Beach Toe and High-Water Line indicators with field data show a better performance of the BT indicator, supporting the use of the proposed indicator on shore platform beaches. The proposed analysis can be easily replicated to other similar rocky coasts, thus representing a much-needed advancement in the study of beaches perched on platform shores.

The Use of UAVs for the Characterization and Analysis of Rocky Coasts

Rocky coasts represent three quarters of all coastlines worldwide. These areas are part of ecosystems of great ecological value, but their steep configuration and their elevation make field surveys difficult. This fact, together with their lower variation rates, explains the lower numbers of publications about cliffs and rocky coasts in general compared with those about beach-dune systems. The introduction of UAVs in research, has enormously expanded the possibilities for the study of rocky coasts. Their relative low costs allow for the generation of information with a high level of detail. This information, combined with GIS tools, enables coastal analysis based on Digital Models and high spatial resolution images. This investigation summarizes the main results obtained with the help of UAVs between 2012 and the present day in rocky coastline sections in the northwest of the Iberian Peninsula. These investigations have particularly focused on monitoring the dynamics of boulder beaches, cliffs, and shore platforms, as well as the structure and function of ecosystems. This work demonstrates the importance of unmanned aerial vehicles (UAVs) for coastal studies and their usefulness for improving coastal management. The Galician case was used to explain their importance and the advances in the UAVs’ techniques.

Loss of canopy-forming algal richness and coverage in the northern Adriatic Sea

Canopy-forming macroalgae, especially those belonging to the order Fucales, are creating the so-called brown algal forests that are considered amongst the most productive assemblages in the shallow coastal area. Moreover, they are biological indicators that are used for the assessment of the status of coastal belts according to important European Directives. Along Mediterranean rocky coasts they are disappearing quickly, Cystoseira species (sensu lato) in particular, and are gradually being replaced by turf-forming smaller and persistent algae, due to multiple anthropogenic pressures. The scope of this research was to verify changes in macrophyte structure and abundance, especially canopy-forming taxa, and the loss of Cystoseira s.l. species at two reference sites for macroalgae in the northern Adriatic Sea, during the period 2007–2019. At both sites, the decline of total Cystoseira s.l. spp. coverage (%) was substantial, both in the spring and autumn samples, while some rare and sensitive species were not found during the last surveys. The results of this study should help improving the conservation status of important canopy-forming species, focusing on the revitalisation of benthic critical habitats.

Relational Risk and Collective Management: A Pathway to Transformational Risk Management.

Risk tends to be conceptualized at the individual scale, with global risk communication and governance efforts fixated on an individual's knowledge and behavior. While individuals are undoubtedly influenced by those who surround them, such human-human interactions tend to be excluded from empirical and field-based analyses of risk taking. This study diverges from prevailing analyses of risk as an individualized phenomenon, exploring the collective and relational practices that influence risk while fishing from hazardous rocky coasts. The aim is to counter the near-universal tendency to individualize risk in empirical analyses by instead using a mixed-methodology that can quantify and enable consideration of collective responses to risk, in real-time. We demonstrate that both rock fishing practice and many of the high-risk events that emerge while rock fishing are managed collectively. Compared to the tendency to individualize risk, we demonstrate that collective responses to risk are more representative of how risk is experienced and acted upon, with implications for risk management in countless contexts.

Unmanned aerial vehicle technology to assess the state of threatened biogenic formations: The vermetid reefs of mediterranean intertidal rocky coasts

Vermetid bioconstructions are biogenic formations, built by sessile gastropod molluscs belonging to the family Vermetidae worldwide distributed, occurring in the intertidal and upper subtidal in the rocky shores. In the Mediterranean basin, they occur in complex and tridimensional structures that enhance the local biodiversity, allowing to qualify the structuring species as ecosystem engineers. Due to their ecological relevance and considerable extension along the coasts, we assessed their structural complexity using unmanned aerial vehicle (UAV) technology, as tool of littoral cartography analysis of these bioconstructions, and plaster hemispheres dissolution as a descriptor index of the water movement on them. We adopted an UAV to produce a very high spatial resolution map along 830m of rocky coast where these vermetid gastropods occur. Through an orthophoto with a GSD (Ground Sample Distance) of 1 cm, different complexity values of indentation degree (or roughness profiles) of the reef boundaries were detected, corroborating literature data carried out with traditional measurement techniques (e.g., tape measure). Our results indicate that the most complex zone of reef is the outer edge, facing the open sea, with a decreasing trend toward the inner edge. Concerning the experimental approach conducted using plaster hemispheres placed along the platform, it reveals that water movement is a structuring factor of the vermetid reef complexity along the rocky coast. Overall, the application of UAV technique allows an appropriate approach to analyze different zones of the vermetid reefs with a high-accuracy on a large spatial scale, greatly reducing sampling effort, and generating important implications for future monitoring and conservation programs.

First Restoration Experiment for Gongolaria barbata in Slovenian Coastal Waters. What Can Go Wrong?

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.

Decreasing in patch-size of Cystoseira forests reduces the diversity of their associated molluscan assemblage in Mediterranean rocky reefs

Canopy-forming seaweeds of the genus Cystoseira (Fucales, Phaeophyceae) form diverse and productive habitats along temperate rocky coasts of the Mediterranean Sea. During the last decade, Cystoseira forests have retracted their range considerably due to many interacting environmental, biological and anthropogenic pressures. We investigated how reducing in patch-size of C. montagnei affects their associated molluscan communities at the shallow northwest rocky shores of Palermo (Sicily, Italy). Molluscs were sampled from the fronds of individual thalli, clumps of 3 and 5 thalli of C. montagnei over an annual vegetative cycle (May–September) in two sites within the Marine Protected Area “Capo Gallo-Isola delle Femmine”. We measured five substrate attributes of the alga (thallus volume, canopy volume, interstitial volume, algal surface, and biomass) and explored their relationships with the diversity of the associated molluscan assemblage. A total of 3756 individuals of molluscs were collected, belonging to 30 families and 57 species, being Rissoidae the most speciose family and Barleeidae the dominant in terms of abundance. The molluscan assemblage on C. montagnei displayed significant spatial and seasonal variations, with the maximum number of individuals and species in summer, whereas evenness and diversity displayed maximum values in spring. The abundance, species richness and diversity of the molluscan assemblage decreased with decreasing in patch-size of C. montagnei, regardless of the vegetative phase of the alga or the sites considered in the study, while evenness showed an opposite trend. The substrate attributes of C. montagnei changed over the vegetative cycle of the alga and showed a similar pattern across sites with values that tended to decrease in autumn during the quiescence phase of the alga. Variation in patch-size of C. montagnei affected also the substrate attributes of the individual alga, with individual thalli becoming smaller with increasing patch-size. The algal surface of a single thallus of C. montagnei ranged on average from 956 cm2 in spring to 289 cm2 in autumn. Furthermore, algal surface together with thallus volume and dry weight were the substrate attributes that explained better the variation of the number of molluscan individuals and species. Overall, our results suggest that the reduction of both patch-size and algal substrate of C. montagnei forests altered the structure and composition of its associated molluscan assemblage. We argue that a reduction or loss of Cystoseira forests could probably trigger bottom-up effects in rocky shores habitats, with consequences for the whole ecosystem structure, functioning and services provided to humans.