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Wave energy has the potential to contribute in the transition to decarbonized electricity generation. Extracting wave energy might be expected to have ecological impacts on rocky shore intertidal communities where exposure is one of the most important factors determining species structure and composition. With global climatic change, coastal exposure is predicted to increase with greater significant wave height. The wave-exposed west coast of Orkney, Scotland, UK, is the site of pre-commercial wave device testing. Surveys of 39 rocky shore sites along this coast identified key species and abundances, and quantified exposure-modifying topographic variables. A spectral wave model was constructed to compare baseline, wave extraction, climate change, and combined scenarios. Generalized additive modelling was used to describe the relationship between species, topography, and exposure. Results show that individual species differentially respond to exposure changes with 'winners' and 'losers' at site level. Overall, community responses are expected to be far greater following predicted climatic change than to industrial-scale wave energy extraction, depending on spatial scale. In combination, energy extraction may reduce the effects of climate-change-related increases in wave exposure of rocky shores. Predicting how location-specific biotic assemblages respond to changes in wave energy as a result of long-term forcing agents provides a valuable marine resource management tool. [ABSTRACT FROM AUTHOR]

Geographic isolation is a factor that is known to affect species composition and diversity in marine systems. In this study, we tested the effects of geographic isolation on invertebrate fauna living among the belt-forming foundation species Fucus vesiculosus in the northern Baltic Sea. Sampling was carried out on reefs with varying levels of isolation (0.5, 1 and 2 km) in July 2021 in the Åland islands (between 59.96°N 20.24°E and 59.75°N 20.84°E). The total number of taxa, abundance, Shannon-Wiener index, Pielou's evenness and biomass were calculated and the effects of isolation were tested using generalised linear models. Multivariate methods were used to analyse differences in the invertebrate community composition. Although the number of taxa and Shannon´s diversity index did not vary along the isolation gradient, the total abundance of fauna decreased with increasing isolation. In addition, some taxa-specific patterns were observed, e.g. the abundance of insect larvae decreased with isolation while isopods were more numerous in the most isolated locations. As diversity and the number of taxa were similar regardless of isolation, shallow Fucus vesiculosus belts likely act as important biodiversity refuges and potential stepping-stones for invertebrates in remote outer archipelago areas. In a changing climate, these kinds of refuges aiding species dispersal are likely to be even more important, and should be considered in conservation planning. [ABSTRACT FROM AUTHOR]

Prosorhochmidae, known as smiling worms, are hoplonemerteans of great interest to nemertologists, since some species display viviparity and hermaphroditism, both rare traits in this phylum, and can be found in terrestrial and marine environments. Prosorhochmus is a predominantly marine genus and was never recorded on the Brazilian coast. The present study documents the first record of the oviparous Prosorhochmus belizeanus, along with population genetic diversity analyses. Here, we sequenced cytochrome c oxidase subunit 1 (COI) and 16S ribosomal RNA (16SrRNA) regions from individuals of three localities along the Brazilian Northeast coast. From these analyses, we found moderate genetic diversity, no genetic structuring, and no clear geographical pattern. In addition, migration analysis evidenced some influence of the Brazilian Current in the species’ dispersion. Those findings indicate colonization by a small number of mtDNA lineages followed by population stability and shed light into the importance of deepening the knowledge about those organisms to elucidate genetic and dispersion patterns of oviparous invertebrates of rocky shores. [ABSTRACT FROM AUTHOR]

Gastropods are ecologically significant and can be found in a wide range of habitats. Their taxonomy is complicated by their perplexing morphological characteristics. Therefore, a molecular based identification approach was used to confirm the variety of gastropod species commonly found on the coast during low tide at rocky shores. In the present investigation, nine species of gastropods were identified using the foresaid modern technique such as (Thalessa savignyi, Purpura persica, Turbo sparverius, Lunella coronata, Cellana karachiensis, Nerita albicilla, Nerita tristis, Ischnochiton australis, Astralium tentorriformis). T our knowledge among them three are news records (A. tentoriiformes, Ischnochiton australis and, Nerita tristis). The highest evolutionary divergence within the family of Nacellidae (0.917) followed by Turbinidae (0.169) and Neritidae (0.100) was noted. The results of this study will be helpful to taxonomists because meager attention was given to molecular- based identification from this region. [ABSTRACT FROM AUTHOR]

Microscopic epibionts on molluscan shells are a component of the biodiversity of intertidal coastal areas. Because molluscan shells are discrete habitats for the epibiont community, and the molluscan basibionts belong to the local community, epibiont diversity can be evaluated hierarchically by basibiont categories including species. To evaluate the structure of epibiont diversity and effects of taxonomic resolution on the evaluation, epibionts on molluscan shells and inert surfaces were investigated at three geographically distant sites in Japan. In total, 94 species-level taxonomic units of epibionts were obtained from 31 basibiont molluscan species and inert surfaces (plastics and rock chips). The density and the species richness at the site of the lowest latitude were significantly lower than those at the other sites. The epibiont community differed between the three sites, although the major portion of the epibionts were diatoms. Between-site diversity contributed most of the total diversity of the species richness and Simpson diversity in the five levels of the hierarchical partitioning: sample (individual basibiont), basibiont species (molluscan species), surface group (bivalves, chitons + limpets, and globose gastropods), site, and the total. The taxonomic resolution did not markedly affect the variability of communities between the three sites, although the taxon richness was reduced to 51 in the genus-level analysis. The lower taxonomic resolution (genus level); however, increased the contribution of the within-sample and decreased the contribution of β diversities at the higher hierarchies, leading to a possible overestimation of biotic homogenization between the communities. [ABSTRACT FROM AUTHOR]

Understanding how synchronous species fluctuations affect community stability is a main research topic in ecology. Yet experimental studies evaluating how changes in disturbance regimes affect the synchrony and stability of populations and communities remain rare. We hypothesized that spatially heterogeneous disturbances of moderate intensity would promote metacommunity stability by decreasing the spatial synchrony of species fluctuations. To test this hypothesis, we exposed rocky shore communities of algae and invertebrates to homogeneous and gradient-like spatial patterns of disturbance at two levels of intensity for 4 years and used synchrony networks to characterize community responses to these disturbances. The gradient-like disturbance at low intensity enhanced spatial ß diversity compared to the other treatments and produced the most heterogeneous and least synchronized network, which was also the most stable in terms of population and community fluctuations. In contrast, homogeneous disturbance destabilized the community, enhancing spatial synchronization. Intense disturbances always reduced spatial ß diversity, indicating that strong perturbations could destabilize communities via biotic homogenization regardless of their spatial structure. Our findings corroborated theoretical predictions, emphasizing the importance of spatially heterogeneous disturbances in promoting stability by amplifying asynchronous spatial and temporal fluctuations in population and community abundance. In contrast to other networks, synchrony networks are vulnerable to the removal of most peripheral nodes, which are less synchronized, but may contribute more to stability than other nodes by dampening large fluctuations in species abundance. Our findings suggest that climate change and direct anthropogenic disturbance can compromise the stability of ecological communities through combined effects on diversity and synchrony, as well as further affecting ecosystems through habitat loss. [ABSTRACT FROM AUTHOR]

Background: The population structure and breeding biology of the Xanthid crab, Leptodius exaratus (H. Milne Edwards, 1834), on the rocky intertidal region of Shivrajpur in Saurashtra coast, Gujarat state, were examined. Method: From March 2021 to February 2022, monthly sampling was conducted during low tide using catch per unit effort in the 500m² area. The sampled specimens were categorised into male, non-ovigerous female or ovigerous female. In order to estimate fecundity, the morphology of the crab specimens (carapace width and body weight) as well as the size of eggs, number of eggs and weight of egg mass were recorded. Results: A total of 1,215 individuals were sampled of which 558 individuals were males and 657 individuals were females. The size (carapace width) of males ranges from 5.15 to 29.98 mm, while females ranges from 5.26 to 28.63 mm which shows that the average size of male and female individuals did not differ significantly. The overall as well as monthly sex ratio was skewed towards males with a bimodal distribution while unimodal in females. The population breeds year-round, which was indicated by the occurrence of ovigerous females throughout the year. However, the maximum percentage occurrence of ovigerous females was observed from December to April which indicates the peak breeding season. The size of eggs, number of eggs and weight of egg mass were shown to positively correlate with the morphology of ovigerous females (carapace width and wet weight). [ABSTRACT FROM AUTHOR]

A preliminary checklist of the mollusks associated with the rocky littoral of Malecón de Santo Domingo is presented. The sampling consisted of an intensive search by niches in two localities selected on the basis of their heterogeneity and access. We preliminarily report 25 species, 19 genera and 14 families of mollusks, with gastropods being the most representative group in species. It is expected that future intensive and diverse sampling methodologies in the studied areas, and other locations, will increase the diversity reported in this note.

Introduction: Sea urchin diseases have been documented in several locations worldwide, with reported occurrences of bacterial, protozoan, fungal, and algal infections. Objective: This study aimed to investigate pathogen agents in populations of Arbacia lixula and Paracentrotus lividus along the coast of Gran Canaria Island (Central-East Atlantic, Spain). Methods: Sampling was conducted at San Cristobal beach, on the Northeast side of the island, where sea urchins were manually collected from depths of 1-3 m during June, July, and October 2022. Swab samples were taken from the external and internal areas of the lesions and cultured on various media plates. Results: Eight different pathogen agents, including bacteria and fungi, were identified, with Vibrio alginolyticus being the most frequently observed bacteria in all diseased sea urchin samples. Additionally, ciliated protozoans were found within the tests, potentially acting as opportunistic parasites. Conclusions: This research provides a unique perspective on bald sea urchin disease by identifying a significant number of associated pathogens, including Candida, previously unreported in diseased organisms. Furthermore, the study highlights the presence of an inflammatory response in tissues with bacterial colonies, offering crucial insights into understanding this sea urchin disease. [ABSTRACT FROM AUTHOR]

Current latitudinal diversity gradient (LDG) meta‐analyses have failed to distinguish one of the most widespread marine habitats, the intertidal zone, as a separate system despite it having unique abiotic challenges and spatially compressed stress gradients that affect the distribution and abundance of resident species. We address this issue by revisiting published literature and datasets on LDGs since 1911 to explore LDG patterns and their strengths in intertidal benthic, subtidal benthic, and pelagic realms and discuss the importance of recognizing intertidal ecosystems as distinct. Rocky shorelines were the most studied intertidal ecosystem encompassing 64.2% of intertidal LDG studies, and 62.9% of studies focused on assemblage composition, while the remaining 37.1% of studies were taxa specific. While our analyses confirmed LDGs in subtidal benthic and pelagic realms, with a decrease in richness toward the poles, we found no consistent intertidal LDGs in any ocean or coastline across hemispheres or biodiversity unit. Analyzing intertidal and subtidal zones as separate systems increased the strength of subtidal benthic LDGs relative to analyses combining these systems. We demonstrate that in intertidal ecosystems across oceans in both hemispheres, a latitudinal decrease in species richness is not readily apparent, which stands in contrast with significant LDG patterns found in the subtidal realm. Intertidal habitat heterogeneity, regional environmental variability and biological interactions can create species‐rich hot spots independent of latitude, which may functionally outweigh a typical latitudinal decline in species richness. Although previous work has shown weaker LDGs in benthic than pelagic systems, we demonstrate that this is caused by combining subtidal and intertidal benthic ecosystems into a single benthic category. Thus, we propose that subtidal and intertidal ecosystems cannot be combined into one entity as the physical and biological parameters controlling ecosystem processes are vastly different, even among intertidal ecosystems. Thus, the intertidal zone offers a unique model system in which hypotheses can be further tested to better understand the complex processes underlying LDGs. [ABSTRACT FROM AUTHOR]

Background and Aims Marine macroalgae ('seaweeds') are critical to coastal ecosystem structure and function, but also vulnerable to the many environmental changes associated with anthropogenic climate change (ACC). The local habitat conditions underpinning observed and predicted ACC-driven changes in intertidal macroalgal communities are complex and probably site-specific and operate in addition to more commonly reported regional factors such as sea surface temperatures. Methods We examined how the composition and functional trait expression of macroalgal communities in SW England varied with aspect (i.e. north–south orientation) at four sites with opposing Equator- (EF) and Pole-facing (PF) surfaces. Previous work at these sites had established that average annual (low tide) temperatures vary by 1.6 °C and that EF-surfaces experience six-fold more frequent extremes (i.e. >30 °C). Key Results PF macroalgal communities were consistently more taxon rich; 11 taxa were unique to PF habitats, with only one restricted to EF. Likewise, functional richness and dispersion were greater on PF-surfaces (dominated by algae with traits linked to rapid resource capture and utilization, but low desiccation tolerance), although differences in both taxon and functional richness were probably driven by the fact that less diverse EF-surfaces were dominated by desiccation-tolerant fucoids. Conclusions Although we cannot disentangle the influence of temperature variation on algal ecophysiology from the indirect effects of aspect on species interactions (niche pre-emption, competition, grazing, etc.), our study system provides an excellent model for understanding how environmental variation at local scales affects community composition and functioning. By virtue of enhanced taxonomic diversity, PF-aspects supported higher functional diversity and, consequently, greater effective functional redundancy. These differences may imbue PF-aspects with resilience against environmental perturbation, but if predicted increases in global temperatures are realized, some PF-sites may shift to a depauperate, desiccation-tolerant seaweed community with a concomitant loss of functional diversity and redundancy. [ABSTRACT FROM AUTHOR]

Plastic pollution is an ever-increasing threat globally and poor waste management in South Africa has caused an increase in plastic leakage into the environment. Plastic waste in the environment are categorized according to size and plastic particles smaller than 5 mm in size are regarded as microplastics (MPs), and little to no research has been done on MPs pollution within the marine coastal environment and rocky shores in South Africa. Sampling was done in February 2020 at a rocky shore within Simon's Town Marina, Cape Town. MPs were extracted from collected water (n = 5), sediment (n = 5) and biota (n ≤ 30) samples. The extracted MPs were further classified based on shape, colour, size and an attenuated total reflectance Fourier-transform infrared (ATR-FTIR) instrument was utilized for polymer type identification The risks posed by MPs because of concentration at which they occurred and chemical composition were assessed in all the sample types. As expected, MPs were higher in sediment (38 ± 2 MP/kg) than in water (0.37 ± 0.06 MP/L) as the area has low water energy, allowing MP particles to settle within the sediment. Filter-feeding organisms had the lowest average MP particle concentrations (0.28 ± 0.04 MP/g) but displayed the highest variation of MP particle colours due to the non-selective feeding strategy, where other feeding strategies ingested mostly black/grey particles. The dominant MP size was between 100 μm and 500 μm in size for all samples combined, with the most abundant MP polymer type being nylon (27.27 %), polyethylene terephthalate (PET) (18.18 %) and natural MP particles such as cotton (18.18 %). The risk assessment indicated that polymer type poses a greater risk of MP pollution than MP concentrations.

Background The population structure and breeding biology of the Xanthid crab, Leptodius exaratus (H. Milne Edwards, 1834), on the rocky intertidal region of Shivrajpur in Saurashtra coast, Gujarat state, were examined. Method From March 2021 to February 2022, monthly sampling was conducted during low tide using catch per unit effort in the 500 m2 area. The sampled specimens were categorised into male, non-ovigerous female or ovigerous female. In order to estimate fecundity, the morphology of the crab specimens (carapace width and body weight) as well as the size of eggs, number of eggs and weight of egg mass were recorded. Results A total of 1,215 individuals were sampled of which 558 individuals were males and 657 individuals were females. The size (carapace width) of males ranges from 5.15 to 29.98 mm, while females ranges from 5.26 to 28.63 mm which shows that the average size of male and female individuals did not differ significantly. The overall as well as monthly sex ratio was skewed towards males with a bimodal distribution while unimodal in females. The population breeds year-round, which was indicated by the occurrence of ovigerous females throughout the year. However, the maximum percentage occurrence of ovigerous females was observed from December to April which indicates the peak breeding season. The size of eggs, number of eggs and weight of egg mass were shown to positively correlate with the morphology of ovigerous females (carapace width and wet weight).

IntroductionThe collapse of macroalgal habitats is altering the structure of benthic communities on rocky shores globally. Nonetheless, how the loss of canopy-forming macroalgae influences the structure of epilithic microbial communities is yet to be explored. MethodsHere, we used experimental field manipulations and 16S-rRNA-gene amplicon sequencing to determine the effects of macroalgal loss on the understory bacterial communities and their relationship with epiphytic bacteria on macroalgae. Beds of the fucoid Hormosira banksii were exposed to different levels of disturbance resulting in five treatments: (i) 100% removal of Hormosira individuals, (ii) 50% removal, (iii) no removal, (iv) a procedural control that mimicked the removal process, but no Hormosira was removed and (v) adjacent bare rock. Canopy cover, bacterial communities (epilithic and epiphytic) and benthic macroorganisms were monitored for 16 months.ResultsResults showed that reductions in canopy cover rapidly altered understory bacterial diversity and composition. Hormosira canopies in 50% and 100% removal plots showed signs of recovery over time, but understory epilithic bacterial communities remained distinct throughout the experiment in plots that experienced full Hormosira removal. Changes in bacterial communities were not related to changes in other benthic macroorganisms.DiscussionThese results demonstrate that understory epilithic bacterial communities respond rapidly to environmental disturbances at small scales and these changes can be long-lasting. A deeper knowledge of the ecological role of understory epilithic microbial communities is needed to better understand potential cascading effects of disturbances on the functioning of macroalgal-dominated systems.

More than half the world's coastlines are rocky, but rip‐current dynamics on these topographically complex shores have not been studied. Field experiments on a typical rocky shore using video, drifters, and in‐situ current meters and pressure sensors reveal that incoming narrow‐banded swells result in incident wave groups that force breakpoint low‐frequency (LF) waves, which act in phase inside the surf zone to generate set‐up, run‐up, overtopping, and mass flux, pooling water atop the shore. Set‐up is enhanced by the change in momentum of the LF waves owing to dissipation by bottom friction over the rough seafloor, and by depth‐limited breaking, evidenced by low reflection. A 1D momentum balance results in a mean bottom‐drag coefficient of 1 owing to the rough bottom and vegetation. During wave‐group minima, the hydraulic head of the pooled water forces a return flow through a network of incised feeder channels that converge to a primary surge channel, directing flow offshore. The rip current extends three surf‐zone widths offshore with a maximum velocity of 1 m/s, and (in contrast to sandy shores) flow exits the surf zone, augmenting cross‐shore transport. Rip current strength is a function of channel hypsometry, overtopping, and exit constriction, factors that vary with the tide. As the tide rises, the mean flow decreases as the hydraulic head decreases and the constriction diminishes. Similar to rip currents on sandy beaches, rip currents on rocky shores are modulated by tides and sea‐swell, but they differ in geometric scale and forcing mechanism. Plain Language Summary: A series of field experiments are performed to understand rip currents associated with surge channels, a characteristic of rocky shores. Information from video observations, Global Positioning System‐equipped drifters, and bottom‐mounted current and pressure sensors was obtained for a low‐lying channel (called a surge channel) at the Hopkins Marine Station, Pacific Grove, CA, which defines the rocky shore rip current. The surge channel is a feeder‐channel network that converges into a primary channel, acting like a nozzle. The strength of the rocky shore rip current and its pulsations are governed by the sea swell waves, the modulated wave group, the tidal elevation, and surge channel geometry. Rocky‐shore surge‐channel rip currents differ from the common rip currents on sandy shores. The differences are related to the steep bottom morphology of rocky shores, which does not adjust over time to incoming sea‐swell waves and has a much smaller geometric scale than rip current morphology for sandy shores; the different morphology results in different forcing mechanisms. In addition, the significantly greater bottom roughness of rocky shores enhances the forcing mechanism. These differences modify the wave transformation, bottom friction, and rip‐current response. Our field experiments describe the kinematics and dynamics of a rocky shore rip current. Key Points: Rocky‐shore rip‐current strength varies with sea swell and low‐frequency (LF) wave forcing, channel geometry and hypsometry, and tide elevationLF pulsations are a significant contribution to the rip currents and change from a reflective to dissipative process with tideIn contrast to rip currents on sandy beaches, retention on this rocky shore is low, augmenting cross‐shore transport [ABSTRACT FROM AUTHOR]

Invasive sun corals (Tubastraea spp.) are spreading along the Brazilian coast where they compete for space with native species, produce chemical compounds with antifouling and anti-predation properties and modify community structure and function. The tropical rocky shores of the Ilha Grande Bay were the first to be invaded in the southwest Atlantic and the Tamoios Marine Protected Area (MPA) within the bay was directly in the path of the spread of Tubastraea. MPAs aim to conserve biodiversity, preventing habitat loss and fragmentation and maintain healthy ecosystems. As healthy communities might better resist invasion the aim of this study was to investigate to what extent the benthic communities of the MPA are resisting the invasion. Baseline data on the abundance of the invasive corals Tubastraea spp. and community structure (cover) were quantified at eight sites over six years. The benthic communities were dominated by multispecies algal turfs, the mat-forming zooantharian Palythoa caribaeorum and the red alga Asparagopsis taxiformis and fell into five community groups two of which contained Tubastraea spp. The number of invaded sites increased over time as did the abundance of Tubastraea spp. in the communities. Tubastraea spp. sequentially invaded the studied communities within the MPA independently of differing community compositions - i.e. they did not offer better biotic resistance than unprotected areas. This was facilitated by the patchy nature of the communities which allowed Tubastraea spp. to get a foothold by initially avoiding species such as P. caribaeorum which offer greater biological resistance. At one site a significant reduction in Tubastraea spp. was detected after mechanical control. We conclude that the MPA's status as a conservation unit was important to attract research and thus for establishing a baseline, quantifying change due to the invasion and focusing limited management resources, but not in providing significant biotic resistance to the invasion. [ABSTRACT FROM AUTHOR]

Extensive intertidal asphalt pavements and oiled sediment accumulations extend more than 20 km along the northern shoreline of Abu Ali Island, located north of Jubail on the Arabian (Persian) Gulf coast of Saudi Arabia. This shoreline oiling likely originated from two platforms in the Nowruz oil field, which spilled oil from 1983 to 1985; this was one of the largest marine spills in history, with shoreline impacts that were little known. In this study, we used a novel methodology that combined remote sensing analyses with hybrid machine learning–geostatistical modeling of field-collected data to quantify the distribution, extent, and volume of these contaminated sediments to investigate the mechanisms for their persistence and to support the development of remediation plans. After nearly 40 years, approximately 25,000 m3 of contaminated sediments remain, with nearly 50% of these buried underneath clean sediments. The presence of exposed or subsurface carbonate beach rock platforms or ramps clearly influences the ongoing persistence of these asphalt pavements by protecting them from physical energy and sediment mobilization. These rock platforms complicate potential remediation options, with more than 66% of the modeled volume of asphalt pavement estimated to be directly on top of and in contact with carbonate beach rock. The asphalt pavements present persistent ongoing PAH toxicity and continually shed smaller fragments when exposed to wave energy along with localized sheens and liquid oil, presenting a pathway for ongoing chronic exposure of biota. [ABSTRACT FROM AUTHOR]

The complex mixture of anthropogenic pressure determines the impact on the marine biota, hampering the ecosystem's functioning. The coast of Alexandria, Egypt, experiences multiple human pressure, including sewage discharge, engineering activities (urbanization) for armoring purposes, and beach nourishment. Hard-bottom polychaete assemblages are demonstrated to reflect coastal areas' environmental status, though their use in monitoring programs is uncommon. The sensitivity of hard-bottom polychaete assemblages in depicting variations in environmental conditions of two sites exposed to the discharge of polluted water and three sites exposed to urbanization was analyzed. The high spatial and temporal variation in species abundance and diversity probably hid differences among the assemblages exposed to the two forms of pressure while highlighting differences among sites exposed to the same impact form. In addition, changes in the algal substrate probably influenced the observed pattern. Temporal variation of salinity and differences in biological oxygen demand (BOD) and the organic matter appeared to indirectly affect polychaete abundance and diversity by favoring tolerant algal taxa such as Ulva sp. Contrary to what was expected, assemblage variation due to site-specific environmental features accounted for more than the variations due to the two forms of human pressure in shaping differences among polychaete assemblages. [ABSTRACT FROM AUTHOR]

Kelp forests, one of the world's most productive ecosystems, have been in decline in many regions in recent years. Climate change, through steady sea warming or marine heatwaves, has led to the disappearance of entire populations, although kelp forest decline may also depend on non-climatic stressors such as grazing. Since the impacts of climate change are projected to continue to intensify for decades, marine protected areas (MPAs) have been suggested as a cost-effective strategy to boost the resilience of marine ecosystems. However, implementing an MPA does not guarantee that all components of the local community will benefit from it. In NW Spain, several stakeholders reported the decline of Laminaria ochroleuca inside the Islas Atlánticas Marine National Park in recent years, but the extent and possible drivers of this decline have not been investigated. Using a combination of quadrat-scale (abundance, biomass) and transect-scale (cover) seasonal surveys over one year, we found striking differences between L. ochroleuca reefs inside and outside the MPA. Populations outside the MPA were the typical canopy forests expected for a perennial kelp, stable year-round and composed mostly of adults. Inside the MPA, however, grazing prevented the canopy phase from being reached. Instead, only mid-sized young plants were detected in autumn, but most had disappeared by winter, and those that remained had been degraded by herbivores to mere blade-less stipes with no growth meristem that eventually perish. Further research seems warranted to monitor whether this phenomenon spreads to nearby kelp beds outside the MPA. Meanwhile, restoring MPA kelp reefs will more likely require efforts to reduce herbivore activity (e.g. translocations, exclusion devices) than to bolster kelp populations. HIGHLIGHTS • Kelp canopies recurrently failed inside a MPA in recent years.• Neither propagule supply nor environmental conditions explain the failure.• Grazers keep a canopy-free state by eradicating recently recruited kelps. [ABSTRACT FROM AUTHOR]

Various physical mechanisms are implicated in the transport of zooplankton to the outer edge of the surf zone, which is the final barrier before reaching the adult habitat of many meroplanktonic organisms. To explore these physical mechanisms, we measured the abundance of zooplankton in the surf zone hourly for 3 consecutive days during strong internal tidal forcing while concurrently measuring winds, currents, and seawater temperature. Strong temperature changes in the water column that were associated with internal tidal bores, as well as onshore coastal winds, coincided with peaks in abundance of barnacle cyprids, gastropods, and bryozoan larvae in the surf zone. This study supports the hypothesis that both internal tidal bores and onshore winds can accumulate zooplankton nearshore, and that these transport mechanisms may act in concert.

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Euendolithic, or true‐boring, cyanobacteria actively erode carbonate‐containing substrata in a wide range of environments and pose significant risks to calcareous marine fauna. Their boring activities cause structural damage and increase susceptibility to disease and are projected to only intensify with global climate change. Most research has, however, focused on tropical coral systems, and limited information exists on the global distribution, diversity, and substratum specificity of euendoliths. This metastudy aimed to collate existing 16S rRNA gene surveys along with novel data from the south coast of South Africa to investigate the global distribution and genetic diversity of endoliths to identify a "core endolithic cyanobacterial microbiome" and assess global diversification of euendolithic cyanobacteria. The cyanobacterial families Phormidesmiaceae, Nodosilineaceae, Nostocaceae, and Xenococcaceae were the most prevalent, found in >92% of categories surveyed. All four known euendolith clusters were detected in both intertidal and subtidal habitats, in the North Atlantic, Mediterranean, and South Pacific oceans, across temperate latitudes, and within rock, travertine tiles, coral, shell, and coralline algae substrata. Analysis of the genetic variation within clusters revealed many organisms to be unique to substratum type and location, suggesting high diversity and niche specificity. Euendoliths are known to have important effects on their hosts. This is particularly important when hosts are globally significant ecological engineers or habitat‐forming species. The findings of this study indicate high ubiquity and diversity of euendolithic cyanobacteria, suggesting high adaptability, which may lead to increased community and ecosystem‐level effects with changing climatic conditions favoring the biochemical mechanisms of cyanobacterial bioerosion. [ABSTRACT FROM AUTHOR]

Aim: Coastal infrastructures are increasing at different latitudes, and their deployment often results in a complete replacement of natural habitats. Although infrastructure provides novel habitats, ecological engineering can increase their similarity to natural rocky habitats. One hurdle for effective design of greener infrastructure is the scarce information on the processes that underpin differences in the structure of communities between built and natural habitats. Using long‐term data of intertidal community structure, we tested whether the magnitude of between‐habitat differences changes with breakwater age and across latitudes, and we examined the role of topographic microhabitats (i.e., rock pools) in driving these differences. Location: Nine locations distributed from 18 to 41°S. Time period: 2016–2020. Methods: We sampled the mid‐intertidal community structure on breakwaters of different age and on natural rocky habitats (platforms and boulder fields) and assessed the availability of microhabitats, such as crevices and rock pools, along a coastline spanning 23° of latitude. Using generalized additive models (GAMs), we assessed the effect of the different factors on species diversity and functional group abundances. Results: Age since construction was a poor predictor of differences between breakwaters and natural habitats. Communities on older breakwaters bore a poor resemblance to the species composition or functional group abundances found in natural habitats. The magnitude of differences between breakwaters and natural habitats varied with latitude, with season and with the type of natural habitat attributable to differences in microhabitats, especially in rock pool availability. Conclusions: Our results indicate that replacement of rocky habitats with breakwaters will cause permanent alterations to coastal ecosystems. Our findings suggest that the availability of microhabitats able to shelter species from stressful environmental conditions is more important at lower and intermediate latitudes; hence, they should be incorporated primarily into infrastructures in tropical or subtropical areas. These strategies could help to compensate for the impacts on rocky ecosystems associated with increases in coastal urbanization. [ABSTRACT FROM AUTHOR]

Limpets are a key taxon regulating the benthic community structure and serving as prey for various predators in rocky shores, however, their role in food web dynamics is still unclear. To determine environmental factors influencing the limpet diet, carbon and nitrogen stable isotopes in limpets and food sources were analyzed on three different coastal habitats. Sediment organic matter contributed the most (86 %) to the limpet diet in bedrocks around tidal flats with abundant sediment supply from the terrestrial matter inflow and the sediment resuspension. Microphytobenthos and macroalgae were the main food sources (57 % and 20 %, respectively) for the limpets around beaches, where benthic flora was abundant. Limpets in bedrocks, erosional habitat, primarily consumed relatively abundant phytoplankton (33 %) and microphytobenthos (28 %). Contrary to previous studies, habitat type, rather than latitude or seawater characteristics, was the most important factor determining the limpet diet. This result also suggests that limpets are non-selective scraper that consume abundant food sources. [Display omitted] • Habitat type was the most important factor determining the limpet diet. • Sediment organic matter was the main food source for limpets around tidal flats. • Benthic flora contributed the most to the limpet diet in bedrocks near beaches. • Limpets in bedrocks primarily consumed microalgae, which are relatively abundant. • Latitude or sea characteristics were not major factors determine the limpet diet. [ABSTRACT FROM AUTHOR]

Rocky shore communities are shaped by complex interactions among environmental drivers and a range of biological processes. Here, we investigated the importance of abiotic and biotic drivers on the population structure of key rocky intertidal species at 62 sites, spanning ∼50% of the Brazilian rocky shoreline (i.e., ∼500 km). Large-scale population patterns were generally explained by differences in ocean temperature and wave exposure. For the gastropod species Lottia subrugosa , differences at smaller scales (i.e., 0.1–1 km) were better explained by other abiotic influences such as freshwater discharge and substrate roughness. Based on the general population patterns of intertidal species identified, three main oceanographic groups were observed: a cold-oligotrophic grouping at northern sites (Lakes sub-region), a eutrophic group associated with large estuaries and urban zones (Santos and Guanabara bays); and a transitional warm-water group found between the two more productive areas. Larger individuals of Stramonita brasiliensis , L. subrugosa and Echinolittorina lineolata were generally found in the cold-oligotrophic system (i.e., upwelling region), while small suspension feeders dominate the warm-eutrophic systems. Evidence of bottom-up regulation was not observed, and top-down regulation effects were only observed between the whelk S. brasiliensis and its mussel prey Perna perna. Environmental drivers as compared to biotic interactions, therefore, play a key role determining the population structure of multiple intertidal species, across a range of spatial scales along the SW Atlantic shores. • Intertidal populations of key species are primarily influenced by seawater temperature. • Temperature and productive gradients determine three trophic oceanographic domains. • Large variability in species density and size was associated to within site differences. • The importance of estuaries on the dynamic of rocky shores is reinforced by their influence on observed patterns. [ABSTRACT FROM AUTHOR]

Abstract We tested the response of algal epifauna to the direct effects of predation and the indirect consequences of habitat change due to grazing and nutrient supply through upwelling using an abundant intertidal rhodophyte, Gelidium pristoides. We ran a mid‐shore field experiment at four sites (two upwelling sites interspersed with two non‐upwelling sites) along 450 km of the south coast of South Africa. The experiment was started in June 2014 and ran until June 2015. Four treatments (predator exclusion, grazer exclusion, control, and procedural control) set out in a block design (n = 5) were monitored monthly for algal cover for the first 6 months and every 2 months for the last 6 months. Epifaunal abundance, species composition, algal cover, and algal architectural complexity (measured using fractal geometry) were assessed after 12 months. Predation had no significant effect on epifaunal abundances, while upwelling interacted with treatment. Grazing reduced the architectural complexity of algae, with increased fractal dimensions in the absence of grazers, and also reduced algal cover at all sites, though the latter effect was only significant for upwelling sites. Epifaunal community composition was not significantly affected by the presence of herbivores or predators but differed among sites independently of upwelling; sites were more similar to nearby sites than those farther away. In contrast, total epifaunal abundance was significantly affected by grazing, when normalized to algal cover. Grazing reduced the cover of algae; thus, epifaunal abundances were not affected by the direct top‐down effects of predation but did respond to the indirect effects of grazing on habitat availability and quality. Our results indicate that epifaunal communities can be strongly influenced by the indirect consequences of biotic interactions.

There is growing evidence that many large coastal boulder deposits found on the exposed rocky ocean shores were deposited by extreme storm waves rather than by catastrophic tsunamis, as previously thought. In addition, before the first discovery in the northern Adriatic a few years ago, such deposits were not expected in relatively shallow semi-enclosed inland basins. Here we report on a large coastal coarse-clast deposit on the central Adriatic island of Mana, which also contains numerous large storm boulders that weigh up to several tons. Large solitary boulders are also located outside of the deposit, closer to the partly submerged sea cliff and the wave impact. The erosion of the cliff top and displacement of the carbonate bedrock fragments began when the extreme waves inundated the lowermost part of the cliff edge, probably during the late Holocene sea-level rise. The UAS photogrammetry-based fragmentation analysis of the storm deposit and the calculated fractal dimension value indicate that the material was fragmented by multiple high-energy events. A comparison of the available photographs indicates that displacements of the most exposed solitary boulders probably occurred during Vaia, the last extreme storm that hit the Adriatic on the 29th of October 2018. However, the modeled maximum wave height south of Mana during the peak of the storm would be insufficient to move these boulders. Yet local geomorphology probably further influenced the increase in wave height that, in combination with specific geological features, caused displacements of the boulders. There is a shorter fetch affecting Mana Island with respect to the northern Adriatic boulder field in southern Istria. Thus, such an active local erosion of the generally stable eastern Adriatic karstic coast depends on the extreme storms that have a weaker impact in the central than in the northern Adriatic. [ABSTRACT FROM AUTHOR]

The intertidal zone on rocky shores is of key ecological importance because it supports high biodiversity, provides critical ecosystem services such as nurseries and refuges, and facilitates complex species interactions in the transition to offshore areas. Important local shaping factors such as groundwater discharge complexify the ecological dynamics of rocky shore communities. The role of submarine groundwater discharge (SGD) in coastal ecosystems is well established. Here, I introduce the Intertidal Groundwater Discharge (IGD) concept to provide a standardised format for distinguishing it from other discharge types. Despite receiving recent increased attention, the importance of direct inland groundwater discharge into intertidal rocky habitats is still scattered. Rocky shores are hallmark habitats long hailed as biodiversity hotspots and key ecological players in adjacent environments; however, consolidated scientific assessments of GW-ecology linkage features and vulnerabilities are lacking. This review is the first to merge fragmented research and identify gaps in knowledge and methodological needs in assessing groundwater-mediated ecological intertidal processes. By filling these gaps, we can gain insights into the vulnerabilities of coastal ecosystems to climate-driven changes related to groundwater availability and design strategies that promote ecological resilience. Rising sea levels, altered precipitation and temperature patterns, and resource exploitation and pollution are increasing threats to the sustainability of rocky shore communities. Here, I integrate hydrogeochemical insights into the broader ecological context of these biodiversity hotspots to develop informed conservation strategies that safeguard the stability and functionality of dynamic and vulnerable habitats., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author. Published by Elsevier Ltd.. All rights reserved.)

The intertidal crustaceans on the Chilean coast are characterized by high diversity and niche specialization. The present study applied a size-overlap null model analysis for intertidal decapod communities in a central Chilean rocky beach (El Quisco, 32°24′S). The application of six models simulations revealed that there is a size overlap, confirmed by the results of all those six simulations. This means that the reported species would share their ecological niches. The results agree with the first classical ecological descriptions for Chilean intertidal decapods at a local scale and support the observations for similar species on the southern Pacific and southern Atlantic coasts, and the results of the null model agree with a first comparative study of decapods in the north and on the central Chilean rocky coast. Resumen: Los crustáceos intermareales de la costa chilena se caracterizan por una alta diversidad y especialización de nicho. El presente estudio aplicó un modelo nulo de superposición de tamaño para comunidades de decápodos intermareales en una playa rocosa de Chile central (El Quisco 32°24′S). Los resultados revelaron que existe una superposición de tamaño aplicando seis simulaciones. Esto significa que las especies reportadas compartirían sus nichos ecológicos. Los resultados concuerdan con las primeras descripciones ecológicas clásicas de los decápodos intermareales chilenos a escala local y respaldan las observaciones de especies similares en las costas del Pacífico sur y del Atlántico sur, y los resultados del modelo nulo concuerdan con un primer estudio comparativo de decápodos en el norte y el costa rocosa de Chile central. [ABSTRACT FROM AUTHOR]

The decapod fauna in the intertidal zone of the rocky shores of Chile is highly diverse, especially along the northern and central mainland coasts, where the influence of the cold Humboldt Current results in high productivity. One of the most abundant species in these ecosystems is the decapod Cyclograpsus cinereus Dana, 1851. The aim of the present study, carried out in the spring and summer seasons between 2018 and 2020, was to determine the spatial distribution patterns of the decapod C. cinereus in different sites along the rocky shores of Antofagasta bay, northern Chile, in order to establish probabilistic models that explain its distribution at each site. Individuals were counted in random quadrants in the intertidal zone. The data thus obtained were processed by application of the variance/mean ratio to determine whether the distribution of individuals was random, aggregated or uniform, associated with Poisson, negative binomial or positive binomial distributions, respectively. The data revealed aggregated (negative binomial) distribution in 15 sampling events, and uniform (positive binomial) distribution in 4 events. The sampling sites were located on rocky shores in four sectors of an urban zone, and two in a protected zone; no significant differences were found between the densities of the sites in the two zones. The results of the interpretative probabilistic models indicated aggregated distribution patterns, agreeing with previously reported interpretative probabilistic models for the distribution of decapods on the rocky shores of central and southern Chile. [ABSTRACT FROM AUTHOR]

Developing approaches to determine the modes of transport and weathering of mafic detrital minerals in natural sedimentary environments is critical to our understanding of sediment production, dispersal and provenance, as well as carbon capture under natural and enhanced weathering regimes. We integrated the characterisation of morphological and surface textures with the surface composition of recent detrital clinopyroxene grains concentrated in a sandy coastal area from the western North Island of New Zealand and a rocky shore area of Santa Maria Island in the Azores Archipelago. Using the compactness shape descriptor, 341 grains were subdivided into elongated, elongated angular, euhedral, angular and subangular groups, with each group further characterised using morphological and microtextural indicators of abrasion, breakage and dissolution/chemical weathering. In both studied environments, the clinopyroxenes are dominated by elongated to angular shapes with flat cleavage surfaces and conchoidal fractures. This is consistent with dominant subaqueous transport by rivers and longshore currents for New Zealand, and dominant wave action with limited sediment supply by rivers along the rocky shore of Santa Maria. More abundant subabraded and abraded shapes with bulbous and elongated depression microtextures are observed in New Zealand, which indicates additional effects by aeolian transport that are not seen in Santa Maria. Consistent with semi-quantitative EDS spot analyses that document fresh clinopyroxenes surfaces, chemical weathering textures are very rare to absent. In Santa Maria, sampling of recent beach sand was complemented by ∼125 kyr-old palaeobeach clinopyroxenes, but these yielded similar textural results without evidence for chemical weathering. However, the surface of these older clinopyroxenes includes small adhering smectite (typically <50 μm in width and a few μm in thickness) interpreted to reflect incipient cementation with buffering of acidic fluids by more reactive lithic fragments in the deposits. The lack of chemical weathering but pervasive evidence for mechanical breakage of clinopyroxenes indicate that, at the sand size, these minerals break faster than they dissolve due to frequent subaqueous and/or aeolian reworking in the studied high-energy environments and temperate climatic conditions. [ABSTRACT FROM AUTHOR]

Extensive intertidal asphalt pavements and oiled sediment accumulations extend more than 20 km along the northern shoreline of Abu Ali Island, located north of Jubail on the Arabian (Persian) Gulf coast of Saudi Arabia. This shoreline oiling likely originated from two platforms in the Nowruz oil field, which spilled oil from 1983 to 1985; this was one of the largest marine spills in history, with shoreline impacts that were little known. In this study, we used a novel methodology that combined remote sensing analyses with hybrid machine learning–geostatistical modeling of field-collected data to quantify the distribution, extent, and volume of these contaminated sediments to investigate the mechanisms for their persistence and to support the development of remediation plans. After nearly 40 years, approximately 25,000 m3 of contaminated sediments remain, with nearly 50% of these buried underneath clean sediments. The presence of exposed or subsurface carbonate beach rock platforms or ramps clearly influences the ongoing persistence of these asphalt pavements by protecting them from physical energy and sediment mobilization. These rock platforms complicate potential remediation options, with more than 66% of the modeled volume of asphalt pavement estimated to be directly on top of and in contact with carbonate beach rock. The asphalt pavements present persistent ongoing PAH toxicity and continually shed smaller fragments when exposed to wave energy along with localized sheens and liquid oil, presenting a pathway for ongoing chronic exposure of biota.

The complex mixture of anthropogenic pressure determines the impact on the marine biota, hampering the ecosystem’s functioning. The coast of Alexandria, Egypt, experiences multiple human pressure, including sewage discharge, engineering activities (urbanization) for armoring purposes, and beach nourishment. Hard-bottom polychaete assemblages are demonstrated to reflect coastal areas’ environmental status, though their use in monitoring programs is uncommon. The sensitivity of hard-bottom polychaete assemblages in depicting variations in environmental conditions of two sites exposed to the discharge of polluted water and three sites exposed to urbanization was analyzed. The high spatial and temporal variation in species abundance and diversity probably hid differences among the assemblages exposed to the two forms of pressure while highlighting differences among sites exposed to the same impact form. In addition, changes in the algal substrate probably influenced the observed pattern. Temporal variation of salinity and differences in biological oxygen demand (BOD) and the organic matter appeared to indirectly affect polychaete abundance and diversity by favoring tolerant algal taxa such as Ulva sp. Contrary to what was expected, assemblage variation due to site-specific environmental features accounted for more than the variations due to the two forms of human pressure in shaping differences among polychaete assemblages.

Theory predicts that species can only coexist if they are sufficiently different in their resource and/or microhabitat utilization; if their needs are too similar, the stronger population will exclude the weaker, unless the two species are equally strong competitors. This hypothesis is difficult to assess in most species because populations are limited by multiple resources simultaneously. In hermit crabs, however, fitness is overwhelmingly limited by gastropod shells, which are their only shelter from external pressures, from predation to harsh environmental conditions. Several hermit crab species have similar shell requirements and occupy the same habitat. Here, we examine the degree of overlap in shell use and microhabitat occupation between two species, one of which (Calcinus californiensis) is clearly dominant over the other (Clibanarius albidigitus) in direct fights over shells. We hypothesized that these species should show microhabitat separation or shell partitioning. We sampled hermit crabs' presence and shell use in the high- and mid-intertidal. The species overlapped in the two intertidal sites, especially at the higher intertidal, and they occupied preferred and suboptimal shells with similar frequency. The co-occurrence and strong overlap in shell use of these two species could be explained by a resource exploitation versus interference trade-off, relaxed selection pressure on shell characteristics due to small body size, spatial/temporal niche segregation, or dominance by Ca. californiensis that has yet to result in habitat displacement of Cl. albidigitus. Further research is needed to determine which of these hypotheses explain the apparent coexistence of ecologically similar species. [ABSTRACT FROM AUTHOR]

Abstract Background Natural populations inhabiting the rocky intertidal experience multiple ecological stressors and provide an opportunity to investigate how environmental differences influence microbiomes over small geographical scales. However, very few microbiome studies focus on animals that inhabit the intertidal. In this study, we investigate the microbiome of the intertidal barnacle Semibalanus balanoides. We first describe the microbiome of two body tissues: the feeding appendages, or cirri, and the gut. Next, we examine whether there are differences between the microbiome of each body tissue of barnacles collected from the thermally extreme microhabitats of the rocky shores’ upper and lower tidal zones. Results Overall, the microbiome of S. balanoides consisted of 18 phyla from 408 genera. Our results showed that although cirri and gut microbiomes shared a portion of their amplicon sequence variants (ASVs), the microbiome of each body tissue was distinct. Over 80% of the ASVs found in the cirri were also found in the gut, and 44% of the ASVs found in the gut were also found in the cirri. Notably, the gut microbiome was not a subset of the cirri microbiome. Additionally, we identified that the cirri microbiome was responsive to microhabitat differences. Conclusion Results from this study indicate that S. balanoides maintains distinct microbiomes in its cirri and gut tissues, and that the gut microbiome is more stable than the cirri microbiome between the extremes of the intertidal.

Environmental heterogeneity contributes to coexistence by allowing species with different traits to persist when different species perform best at different times or places. This interaction between niche differences and environmental variability may also help explain relationships between biodiversity and ecosystem functioning, but few data are available to rigorously evaluate this hypothesis. We assessed how a biologically relevant aspect of environmental heterogeneity interacts with species diversity to determine ecosystem processes in a natural rocky intertidal community. We used field removals to factorially manipulate biogenic habitat heterogeneity (barnacles, bare rock, and plots that were 50/50 mixes of the two habitat types) and gastropod grazer species richness and then tracked algal community succession and recovery over the course of 1 yr. We found that herbivore diversity, substrate heterogeneity, and their interaction played unique roles in the peak abundance and timing of occurrence of different algal functional groups. Early successional microalgae were most heavily grazed in diverse herbivore assemblages and those with barnacles present, which was likely due to complementary feeding strategies among all three grazers. In contrast, late successional macroalgae were strongly influenced by the presence of a habitat generalist limpet. In this herbivore's absence, heterogeneous habitats (i.e., mixtures of bare rock and barnacles) experienced the greatest algal accumulation, which was partly a result of complementary habitat use by the remaining herbivores. The complex way habitat identity and heterogeneity altered grazer-algal interactions in our study suggests species' differences and environmental heterogeneity both separately and interactively contribute to the relationship between biodiversity and ecosystem functions.

Google Earth Engine is used to trace the spatial distribution of the lacustrine coastal megaclast deposits (LCMDs) of the Lake Malawi. Wide distribution of LCMDs is established, and they are especially common on the northeastern and southern coasts. The studied deposits can be subdivided provisionally into lenticular, patchy, and point-scale categories. Apparently, the spatial distribution of these deposits around the Lake Malawi is controlled by the regional geology and topography. This case study proves the efficacy of the virtual journeys for quick finding and mapping LCMDs along lake coasts, although not for their quantitative analysis and in-depth descriptions. [ABSTRACT FROM AUTHOR]

We tested the response of algal epifauna to the direct effects of predation and the indirect consequences of habitat change due to grazing and nutrient supply through upwelling using an abundant intertidal rhodophyte, Gelidium pristoides. We ran a mid‐shore field experiment at four sites (two upwelling sites interspersed with two non‐upwelling sites) along 450 km of the south coast of South Africa. The experiment was started in June 2014 and ran until June 2015. Four treatments (predator exclusion, grazer exclusion, control, and procedural control) set out in a block design (n = 5) were monitored monthly for algal cover for the first 6 months and every 2 months for the last 6 months. Epifaunal abundance, species composition, algal cover, and algal architectural complexity (measured using fractal geometry) were assessed after 12 months. Predation had no significant effect on epifaunal abundances, while upwelling interacted with treatment. Grazing reduced the architectural complexity of algae, with increased fractal dimensions in the absence of grazers, and also reduced algal cover at all sites, though the latter effect was only significant for upwelling sites. Epifaunal community composition was not significantly affected by the presence of herbivores or predators but differed among sites independently of upwelling; sites were more similar to nearby sites than those farther away. In contrast, total epifaunal abundance was significantly affected by grazing, when normalized to algal cover. Grazing reduced the cover of algae; thus, epifaunal abundances were not affected by the direct top‐down effects of predation but did respond to the indirect effects of grazing on habitat availability and quality. Our results indicate that epifaunal communities can be strongly influenced by the indirect consequences of biotic interactions. [ABSTRACT FROM AUTHOR]

The intertidal crustaceans on the Chilean coast are characterized by high diversity and niche specialization. The present study applied a size overlap null model for intertidal decapod communities at four different sites on the Chilean coast. The results revealed that there is a size overlap for the four sites, though body size is significantly different for each location. This means that the reported species would share their ecological niches. The results agree with the first classic environmental descriptions for Chilean intertidal decapods at a local scale and support the observations for similar species on the southern Pacific and southern Atlantic coasts.

One specimen (38.3 mm SL) of Neoclinus lacunicola Fukao, 1980, belonging to the family Chaenopsidae, was first recorded from Ulleung Island, Korea (East Sea, otherwise known as the Sea of Japan) on 5 January 2021. This species was characterized by paired external pores of incomplete lateral line running from the upper margin of the opercle, seven pairs of supraorbital cirri arranged in two rows, occipital region with a pair of cirri, and 13 rays of pectoral fin. This species is morphologically similar to the Neoclinus toshimaensis Fukao, 1980, but differs in the number of cirri on the supraorbital (6--7 versus 9--11 cirri). This study documents the first report of N. lacunicola in Korean waters and proposes the new Korean name of 'eol-lug-bi-neul-be-do-la-chi' for the species. For the confirmation of the identity of the species, a partial gene sequence of the mt COI (570 bp) of N. lacunicola was obtained for the first time. [ABSTRACT FROM AUTHOR]

Genetic investigations of members of the bivalve genus Lasaea have revealed unexpected diversity in the genus, as well as close affiliations between geographically distant populations. Here we investigate the phylogeography of the New Zealand species L. hinemoa using mitochondrial and nuclear gene sequences (cytochrome c oxidase subunit III and Internal Transcribed Spacer 2, respectively) from populations around the country. Additionally, we designed novel microsatellite markers, which enabled us to check the specific species status implied by the two single-gene markers. Lasaea hinemoa individuals fell into four clades. Clades I and III were numerically dominant, with a suggestion of some biogeographic structure around the coasts of mainland New Zealand, and we argue they represent separate cryptic species. Samples from the subantarctic Antipodes Island contained individuals from two clades (I and II). The latter clade is close to populations from the Kerguelen Islands, which suggests possible transoceanic dispersal via the Antarctic Circumpolar Current. Clade IV, represented by small numbers of individuals from Picton and Mahia, appears to be the result of transoceanic dispersal by yet another Lasaea species. [ABSTRACT FROM AUTHOR]

Abstract The intertidal rocky shores in continental Chile have high species diversity mainly in northern Chile (18-27° S), and one of the most widespread species is the gastropod Echinolittorina peruviana (Lamarck, 1822). The aim of the present study is do a first characterization of spatial distribution of E. peruviana in along rocky shore in Antofagasta town in northern Chile. Individuals were counted in nine different sites that also were determined their spectral properties using remote sensing techniques (LANDSAT ETM+). The results revealed that sites without marked human intervention have more abundant in comparison to sites located in the town, also in all studied sites was found an aggregated pattern, and in six of these sites were found a negative binomial distribution. The low density related to sites with human intervention is supported when spectral properties for sites were included. These results would agree with other similar results for rocky shore in northern and southern Chile.

There is growing evidence that many large coastal boulder deposits found on the exposed rocky ocean shores were deposited by extreme storm waves rather than by catastrophic tsunamis, as previously thought. In addition, before the first discovery in the northern Adriatic a few years ago, such deposits were not expected in relatively shallow semi-enclosed inland basins. Here we report on a large coastal coarse-clast deposit on the central Adriatic island of Mana, which also contains numerous large storm boulders that weigh up to several tons. Large solitary boulders are also located outside of the deposit, closer to the partly submerged sea cliff and the wave impact. The erosion of the cliff top and displacement of the carbonate bedrock fragments began when the extreme waves inundated the lowermost part of the cliff edge, probably during the late Holocene sea-level rise. The UAS photogrammetry-based fragmentation analysis of the storm deposit and the calculated fractal dimension value indicate that the material was fragmented by multiple high-energy events. A comparison of the available photographs indicates that displacements of the most exposed solitary boulders probably occurred during Vaia, the last extreme storm that hit the Adriatic on the 29th of October 2018. However, the modeled maximum wave height south of Mana during the peak of the storm would be insufficient to move these boulders. Yet local geomorphology probably further influenced the increase in wave height that, in combination with specific geological features, caused displacements of the boulders. There is a shorter fetch affecting Mana Island with respect to the northern Adriatic boulder field in southern Istria. Thus, such an active local erosion of the generally stable eastern Adriatic karstic coast depends on the extreme storms that have a weaker impact in the central than in the northern Adriatic.

Mytilus galloprovincialis is an ecosystem engineer that provides habitat and generates environmental heterogeneity, increasing local biodiversity. Moreover, it is an economically important species representing 14% of the global production of marine bivalves. Natural drivers and the increase of anthropogenic pressures, such as sediment stress, influence its populations on rocky shores. The objective of this study was to explore the spatial-temporal patterns of different M. galloprovincialis attributes along the north of Portugal. For that purpose, six rocky shores were selected and sampled six times along the year 2019. The percentage of cover, density, spat density, condition index, clump thickness, size classes and clump sediment content were considered. Results showed the lack of seasonality in M. galloprovincialis along the north coast of Portugal. However, density, spat stage, clump thickness, condition index and size classes showed some variability among dates and shores. The percentage cover and sediment content only significantly differed among shores. Our results indicated an absence of seasonality for all the studied variables, probably because temperature was always within the optimum range for this species and the abundance of food supply in the study area independently of the season. The accumulated sediment on mussel clumps did not show any temporal variability with only significant differences among shores. The accumulated sediment was composed mainly by medium and coarse sand and it was correlated with mussel average size, condition index, but especially with the mussel clump thickness.

Mytilus galloprovincialis is an ecosystem engineer that provides habitat and generates environmental heterogeneity, increasing local biodiversity. Moreover, it is an economically important species representing 14% of the global production of marine bivalves. Natural drivers and the increase of anthropogenic pressures, such as sediment stress, influence its populations on rocky shores. The objective of this study was to explore the spatial-temporal patterns of different M. galloprovincialis attributes along the north of Portugal. For that purpose, six rocky shores were selected and sampled six times along the year 2019. The percentage of cover, density, spat density, condition index, clump thickness, size classes and clump sediment content were considered. Results showed the lack of seasonality in M. galloprovincialis along the north coast of Portugal. However, density, spat stage, clump thickness, condition index and size classes showed some variability among dates and shores. The percentage cover and sediment content only significantly differed among shores. Our results indicated an absence of seasonality for all the studied variables, probably because temperature was always within the optimum range for this species and the abundance of food supply in the study area independently of the season. The accumulated sediment on mussel clumps did not show any temporal variability with only significant differences among shores. The accumulated sediment was composed mainly by medium and coarse sand and it was correlated with mussel average size, condition index, but especially with the mussel clump thickness. [ABSTRACT FROM AUTHOR]