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The distribution of genetic diversity is often heterogeneous in space, and it usually correlates with environmental transitions or historical processes that affect demography. The coast of Chile encompasses two biogeographic provinces and spans a broad environmental gradient together with oceanographic processes linked to coastal topography that can affect species' genetic diversity. Here, we evaluated the genetic connectivity and historical demography of four Scurria limpets, S. scurra, S. variabilis, S. ceciliana and S. araucana, between ca. 19° S and 53° S in the Chilean coast using genome‐wide SNPs markers. Genetic structure varied among species which was evidenced by species‐specific breaks together with two shared breaks. One of the shared breaks was located at 22–25° S and was observed in S. araucana and S. variabilis, while the second break around 31–34° S was shared by three Scurria species. Interestingly, the identified genetic breaks are also shared with other low‐disperser invertebrates. Demographic histories show bottlenecks in S. scurra and S. araucana populations and recent population expansion in all species. The shared genetic breaks can be linked to oceanographic features acting as soft barriers to dispersal and also to historical climate, evidencing the utility of comparing multiple and sympatric species to understand the influence of a particular seascape on genetic diversity. [ABSTRACT FROM AUTHOR]

The unprecedented rates of current biodiversity loss have motivated a renewed interest in environmental and biodiversity monitoring. The need for sustained monitoring strategies has prompted not only the establisment of new long-term monitoring programmes, but also the rescue of data from historical or otherwise archived sources. Amongst the most valuable datasets are those containing information on intertidal systems, as they are particularly well suited for studying the biological effects of climate change. The Portuguese rocky coast is quite interesting for studying the effects of climate change on the distribution of species due to its geographical orientation, latitudinal patterns in temperature, species richness, species' distribution patterns and availability of historical information. This work aims at providing a comprehensive picture of the distribution and abundance of intertidal macro-invertebrates and macro-algae along the Portuguese rocky coast in the early 2000s.This study provides a description of the rocky shore intertidal biodiversity of the mainland Portuguese coast in the early 2000s. The spatial distribution and semi-quantitative abundance of a total of 238 taxa were assessed at 49 wave-exposed locations. These data provide a comprehensive baseline against which biodiversity changes can be effectively and objectively evaluated.

Bouet, A.; Collin, A.; James, D.; Rintz, C-L.; Dusseau, P.; Lesacher, M., and Feunteun, E., 2024. On the synergy of the UAV spatial modelling and citizen science for tidal coasts: The case of canopy-forming macroalgae and gastropods on the Emerald Coast, Brittany, France. In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 154-158. Charlotte (North Carolina), ISSN 0749-0208. Coastal marine ecosystems provide crucial services to cope with accelerating global changes. Among them, intertidal rocky shores and their canopy-forming macroalgal habitats support a high biodiversity, provide food, offer coastal protection, and multiple cultural services. Due to their location, at the land-sea interface, these coastal areas are threatened by various distal and local anthropogenic pressures. Their monitoring at very high (dm) spatial resolution is necessary to better inform their sustainable management. The very high temporal resolution of the unmanned airborne vehicle (UAV) imagery can be agile enough to monitor intertidal shores during the low tide's short window. Active or passive UAV imagery, coupled with machine learning, has the capabilities to map habitats, but requires ground-truth data, whose amount is strongly constrained by the low tide period. The study proposes to combine quantitative information, collected by trained citizens, with UAV data. UAV-based data were collected using two different sensors: a topographic Light Detection and Ranging (LiDAR) system DJI L1 and a multispectral imager MicaSense Altum-PT. Linear regressions of the canopy-forming macroalgae cover and the abundance of the gastropod, Steromphala umbilicalis, were run based on UAV by-products. Multispectral orthomosaics better predicted the algae cover (R2 = 0.52) and the abundance of gastropod (R2 = 0.45) than lasergrammetric data (algae cover: R2 = 0.48; gastropod abundance: R2 = 0.42). A combination of both source of data revealed better prediction for the algae cover (R2 = 0.68), as well as for the gastropod abundance (R2 = 0.55). Results are discussed in the light of the cm-scale remote sensing but also in its aspect of environmental awareness and responsive action. [ABSTRACT FROM AUTHOR]

Global warming has been causing severe impacts on marine ecosystems, a notorious one being shifts in the geographical ranges of species. The north-western coast of the Iberian Peninsula is an especially interesting zone to study distributional shifts as it has a strong latitudinal thermal gradient, is influenced by the Canary upwelling system (which partially cancels coastal warming) and holds some of the most diverse macroalgae communities in Europe. Notably, it is within this region that many cold-water species, common in northern Europe, have their southernmost distribution refuge. Recent studies hypothesize that the environmental conditions may be nonetheless changing and already threatening this biodiversity hotspot. The main goal of this study was to carry out a fine-scale assessment of the distributional limits of several macroalgae in North-western Iberia, as well as identify possible population and range shifts using historical data (2001-2005) as reference. In addition, non-indigenous species were also surveyed. We also assessed if the regions of (i) Galicia, (ii) Northern Portugal, and (iii) Central Portugal displayed distinctive characters regarding macroalgae composition and abundance. We identified an increase in abundance of some non-indigenous macroalgae as well as a decrease in the abundance of some cold-water species. In the most severe cases, cold-water species were extirpated along hundreds of km. The compounded effect of the decrease in the abundance of cold-water species and the increase in the abundance of non-indigenous species is leading to the homogenization of macroalgae communities in north-western Iberia.

Background Climate change has been increasing at an unprecedented rate in the last decades. Global warming has been causing a variety of impacts in marine ecosystems, including shifts in the geographical ranges of species. The north-western Iberian Peninsula coast is particularly interesting to study distribution shifts as it features a strong latitude thermal gradient, establishing a biogeographical transitional region where several cold- and warmadapted species have their equatorward or poleward distributions. In the early 2000s, it appeared that, while warm-water species were already responding to warming, cold-water species did not display a coherent response. It is now necessary to gather up-to-date data on the distribution of the same group of species to understand if current patterns of change confirm or deny those observed back then, which may give us important clues about the mechanisms setting species limits in the area. New information This study provides a fine-scale description of the occurrence of intertidal macroalgae species in the rocky shores of the north-western Iberian coast. Specifically, the spatial distribution and semi-quantitative abundance of 34 native and invasive species were assessed at 70 wave-exposed locations. This included 19 species of cold-water affinity, 10 species of warm-water affinity and five neutral species. When contrasted with historical observations, these new data can be used to quantify and map biodiversity change in the region, as well as help understanding the mechanisms constraining species distributions. [ABSTRACT FROM AUTHOR]

Mollusks are a very important component of the invertebrate faunal biodiversity in marine ecosystems. However, knowledge on this (and other groups) is still incomplete. Inventories of fauna are very important tools to learn the biodiversity associated with specific regions and of specific zoological groups. In this paper, I report 103 species of heterobranch mollusks occurring along the Pacific coast of Colombia, including previous peer-reviewed records and new information. Of these, 23 are new records for the Pacific coast of Colombia, and a total of 32 species are registered for the first time in at least one locality along this shore. The most species diverse family is Chromodorididae, followed by Ellobiidae. The most diverse locality is Gorgona Island, closely followed by Malpelo Island. There is still much to learn from this rather isolated region, the northern Pacific coast of the South American continent. [ABSTRACT FROM AUTHOR]

Populations within the same species range edge may experience contrasting local conditions and exhibit diverse levels of environmental tolerance. This heterogeneity within a range boundary has seldom been considered in studies forecasting the impact of anthropogenic habitat alteration and climate change on species distributions. Moreover, any ecological prediction under changing environmental conditions requires a good understanding of the combined responses of organisms to multiple stressors, in particular the effects on key life cycle stages of species. The intertidal seaweed Fucus serratus is a dominant species on northern Atlantic shores and whose southern limit is in the NW Iberian Peninsula. We examined how early developmental stages of southern-edge populations of this foundation alga responded to the combined effects of environmental stressors, including salinity and aerial and seawater temperature. Four populations from two different areas of the NW Iberian coast were considered: two populations from open shores on the northern coast and two populations from the western rias on the Atlantic coast. The study findings revealed inter-population variability in the response to heat stress, with greater survival of germlings from the northern populations than those from western rias. Environmental conditions are still more benign within western rias, under the influence of strong summer upwelling events. The results also suggest the key role of aerial thermal stress in determining the southern limit of distribution of the target species. The future of these heterogeneous edge populations from NW Iberian Peninsula depends on trends in climate change and the ability of populations to cope with these. Environmental changes may already be occurring at rates that exceed the plastic and adaptive potential of edge populations in N Spain, while the future of western rias as climate refugia for this and other foundation alga is also uncertain. [ABSTRACT FROM AUTHOR]

Background: The unprecedented rates of current biodiversity loss have motivated a renewed interest in environmental and biodiversity monitoring. The need for sustained monitoring strategies has prompted not only the establisment of new long-term monitoring programmes, but also the rescue of data from historical or otherwise archived sources. Amongst the most valuable datasets are those containing information on intertidal systems, as they are particularly well suited for studying the biological effects of climate change. The Portuguese rocky coast is quite interesting for studying the effects of climate change on the distribution of species due to its geographical orientation, latitudinal patterns in temperature, species richness, species' distribution patterns and availability of historical information. This work aims at providing a comprehensive picture of the distribution and abundance of intertidal macro-invertebrates and macro-algae along the Portuguese rocky coast in the early 2000s. New information: This study provides a description of the rocky shore intertidal biodiversity of the mainland Portuguese coast in the early 2000s. The spatial distribution and semi-quantitative abundance of a total of 238 taxa were assessed at 49 wave-exposed locations. These data provide a comprehensive baseline against which biodiversity changes can be effectively and objectively evaluated. [ABSTRACT FROM AUTHOR]

Identifying susceptible regions where biodiversity changes occur at fast rates is essential in order to protect and ameliorate affected areas. Large-scale coastal monitoring programs that focus on long-term variability are scarce, yet the Marine Biodiversity Observation Network Pole to Pole is currently developing a regional collaboration throughout the American continent collecting biodiversity data in coastal habitats with a standardized systematic protocol. The use of photographic methods to collect assemblage data on intertidal rocky shores can be appropriate. The goal of this study was to analyze the performance of a simple, low-cost, non-destructive and low-tech photographic method on a broad geographical scale (∼ 2,000 km) of Atlantic Patagonian coastline. Concurrently, we aimed to identify indicators whose cover, presence or condition can be followed in time and used as beacons of change in biodiversity on these rocky intertidal shores. We also explored the potential relationships between assemblage structure and environmental variables, such as seascape classes. We identified and propose cover of mytilids, Corallina spp. and bare substrate as indicators of change due to their ecological relevance in intertidal assemblages and their visible and rapid response to human stressors or changes in environmental conditions. Finally, we illustrate the practicality and usefulness of remotely accessible environmental data, for instance the seascape classes approach as an integrative tool for large-scale rocky shore studies.

It is commonly assumed that the pelagic cyprid larvae of acorn barnacles must permanently attach to a substrate before metamorphosing to the benthic juvenile stage. We show that this is not always the case and demonstrate that some cyprids can metamorphose in the water column, i.e. without first becoming cemented to a surface. We observed early-metamorphosing cyprids to fully developed juveniles in coastal plankton samples during the 2018 recruitment season of Semibalanus balanoides (Linnaeus, 1767) in Atlantic Canada. We demonstrated through a laboratory experiment that cyprids can be induced to fully metamorphose into pelagic juveniles. These novel findings raise the question of whether this phenomenon may also occur in other barnacle species. [ABSTRACT FROM AUTHOR]

Nowadays, coastal urbanization is one of the most serious and prevalent pressures on marine ecosystems, impacting their biodiversity. The objective of this study was to explore differences in attributes and biodiversity associated with an intertidal ecosystem engineer, the mussel Mytilus galloprovincialis Lamarck, 1819 between urban and non-urban shores. For this, mussel attributes and their associated macrofauna were compared between urban and non-urban rocky shores in the north of Portugal. Results showed that the largest sized mussels were more frequent on urban shores, whereas the smallest size class was only present in non-urban shores. Regarding macrofauna associated with mussels, the number of taxa was significantly higher on non-urban shores. Moreover, the structure of the macrobenhic assemblages was significantly different between urban and non-urban shores. Most important taxa responsible for differences were more abundant on non-urban shores except for Nucella lapillus, Idotea pelagica and Oligochaeta that were more abundant on urban shores. Therefore, our results showed that the mussel size frequency and the structure of the associated macrobenthic assemblages changed in urban shores. Considering the relevance of mussel beds for biodiversity and human well-being, our results indicate the need of adopting proper management plans to minimize these effects on urban intertidal ecosystems.

Several researches have been conducted to explain patterns of the abundance, richness and taxonomic diversity of benthic polychaetes; however, such analyses have ignored the functional diversity of polychaete communities, especially feeding guilds in intertidal rocky shores. The present study was carried out to describe and analyse the polychaete feeding guilds on intertidal rocky shores and then examine the effects of environmental factors. Twelve intertidal rocky shores from the coastal protected area of Essaouira (Atlantic coast of Morocco) were sampled during the summer of 2016. A total of 42 polychaete species belonging to 29 genera and 16 families were identified among the 4517 specimens collected. The medium biomass per sampling site was found to be 37.61 ± 15.80 g.m-2. The polychaete species were classified into five feeding guilds, and nine feeding modes. The filter feeders were the dominant feeding guild (32%) followed by omnivores (23%), burrowers (20%), carnivorous (15%) and surface deposit-feeders (10%). The FDT (filter feeder, discretely motile, with tentacles) was the most abundant feeding mode, accounting for 24% of abundance (mainly represented by Sabellaria alveolata), followed by the ODJ feeding mode (omnivorous, discretely motile, with jaw apparatus) with 22%, and the SDT feeding mode (surface deposit feeder, discretely motile, with tentacles) with 18.9%. The highest trophic importance index and index of trophic diversity values were recorded in the southern region of Essaouira coastline. Based on the canonical correspondence analysis, composition and spatial distribution of polychaete feeding guilds were mainly related to the length of rocky shores and water temperature. [ABSTRACT FROM AUTHOR]

This paper describes a dataset of polychaetes (Annelida) from 14 midlittoral rocky shore sampling sites in Greece and Italy (Mediterranean Sea). The dataset combines the outcome of four different projects studying the hard substrate midlittoral zone in the Mediterranean between 1984 and 2009. Samples were collected by scraping and collecting the organisms from a framed area. The maximal sampling depth was 1.5 m. In total, 123 polychaete species were recorded, five of which are new records for the respective biogeographic sectors of the Mediterranean. The dataset contains 788 occurrence records, fully annotated with all required metadata. These data contribute to the knowledge of a previously very understudied regional habitat, since at present, comprehensive lists of the midlittoral communities in the Mediterranean are provided through only a few, paper-based, studies. This dataset is one of the first electronic data compilations of the Mediterranean midlittoral zone communities and certainly the most comprehensive of its kind, contributing to the ongoing efforts of the Ocean Biogeographic Information System (OBIS) which aims at filling the gaps in our current knowledge of the world's oceans. It is accessible at http://ipt.vliz.be/resource.do?r=mediterraneanpolychaetaintertidal.

Twenty-three rocky shores along approximately 225 km on the southwest coast of the Bay of Biscay were sampled during the springs of 2014 and 2021, to explore changes in the distribution and abundance of four non-indigenous species (NIS) macroalgae (i.e., Asparagopsis armata , Grateloupia turuturu , Sargassum muticum , and Undaria pinnatifida) by using a semi-quantitative scale. Results showed relevant changes in the distribution and abundance of NIS. The kelp U. pinnatifida was recorded in 2021 for the first time on two shores. The distribution of G. turuturu showed an extension in its range of distribution of 200 km to the east. The other two target species S. muticum and A. armata were widely distributed along the whole 225 km of the studied area in 2014 and 2021, with higher abundance in 2021. Therefore, we strongly advise the necessity of future monitoring programs for these four NIS species. These monitoring programs will explore the progress of invasion and resilience of native species. • Results showed relevant changes in the distribution of NIS macroalgae in SW Bay of Biscay. • G. turuturu showed an extension of 200 km in its range of distribution in the area. • U. pinnatifida was recorded in 2021 for the first time in SW Bay of Biscay. • S. muticum and A. armata are widely distributed along the 225 km of SW Bay of Biscay. • Future monitoring programs for these four NIS macroalgae species are necessary. [ABSTRACT FROM AUTHOR]

Macroalgal canopies are important ecosystem engineers, contributing to coastal productivity and supporting a rich assemblage of associated flora and fauna. However, they are often absent from infrastructures such as coastal defences and there has been a worldwide decline in their distribution in urbanised coastal areas. The macroalga Fucus spiralis is the only high-shore canopy forming species present in the Azores. It is widely distributed in the archipelago but is never found on coastal infrastructures. Here we evaluate factors that may potentially limit its establishment on artificial structures. A number of observational and manipulative experiments were used to test the hypotheses that: (i) limited-dispersal ability limits the colonisation of new plants onto artificial structures, (ii) vertical substratum slope negatively influences the survivorship of recruits, and (iii) vertical substratum slope also negatively influences the survivorship and fitness of adults. Results showed that the limited dispersal from adult plants may be a more important factor than slope in limiting the species ability to colonise coastal infrastructures, since the vertical substratum slope does not affect its fitness or survivorship. [ABSTRACT FROM AUTHOR]

A fundamental problem in ecology is to link spatial arrangements of key biota and the scale at which organisms interact with each other to structure communities and influence ecosystem functioning. Limpets are widely acknowledged to play an important role in the ecology of intertidal rocky shores and exert the strongest grazing effect of any marine grazer. As a consequence, to understand rocky shore dynamics it is necessary to understand the processes that control spatial and temporal patterns of limpet foraging. Much is known about how limpets behave and their distribution during low tide while at rest, and where and when limpets forage. However, it is less well understood how the behaviour and distribution of the same individuals within these two phases of activity can interact. At the smallest spatial scale, several species of limpet exhibit population-level biases in orientation during low tide. If orientation influences where and when limpets forage, this bias may lead to a directional bias in foraging direction and location during high tide, and potentially to patchy grazing. On the other hand, foraging location may determine low tide orientation. We tested these ideas by comparing the low tide orientation of individual limpets ( Cellana tramoserica ) with foraging frequency, and the relative direction of travel while foraging. We found that though there was an overall bias in departure angle and foraging location, there was no relationship between low tide orientation of individuals and their departure angle. Instead, prior to departure limpets rotated on their resting site to face a new direction. There was also no link between the direction of travel of limpets returning from foraging and their final low tide orientation, as limpets actively rotated on arrival at their resting site. Our findings suggest that there is little or no direct link between the orientation of an individual and its subsequent foraging, nor the converse. Limpets instead actively select both their orientation and the direction they depart for foraging by rotation on their resting site. These results decouple the small scale tide-out resting distribution and orientation of grazers from their ecological functioning. Therefore noting the location of limpets at low tide has limited use for predicting ecological consequences of their grazing. [ABSTRACT FROM AUTHOR]

The article presents a study that investigated the relationship between sudden changes or thresholds in marine ecosystems and the theory of multiple stable states to determine how thresholds can occur in parameters, processes and ecosystem states. Researchers showed that thresholds and hysteresis-like behavior are possible in linear systems using a 2-species Lotka-Volterra model of competition. They also addressed the confusion caused by the different meanings of thresholds by reviewing the concept of thresholds within the context of multiple stable states.

Abstract: Top-down effects on intertidal communities concern species interactions such as competition and predation, and occur on small-scales. In contrast, bottom-up factors concern the supply of resources such as food and recruits. These are generally understood to be large-scale effects that are oceanographically controlled. Here we examined the effects of small-scale bottom-up factors on the growth of intertidal mussels to test the hypothesis that such factors can also operate on small (cmm) spatial scales. L-shaped aluminium baffles were used to reduce flow around mussels on very small (cm) scales in before/after experiments run at different sites in 2004 and 2006. Each experiment had two phases, each phase lasting approximately 100days. At the start of phase one, mussels were individually marked at the growing edge of the shell in 10 control and 10 treatment patches before applying the treatment. At the start of phase 2, the same individuals were marked again at the new growing edge and baffles were placed around treatment patches. After phase one, there was no significant difference in growth rates between treatments in either year. In both years, applying the treatment reduced growth rates by approximately 30% compared to control patches. Condition index at the end of phase two showed the reverse and was lower for control mussels. Untreated control patches also showed a significant temporal effect (i.e. differences in growth between the two phases) during 2004 but not 2006. The results clearly show that bottom-up factors associated with food-supply operate at very small, within-shore scales, strongly influencing growth rates and possibly competitive abilities. They also indicate that bottom-up and top-down effects can interact across multiple spatial scales. [Copyright &y& Elsevier]

The article presents a study that deals with variations in intertidal assemblages and zonation patterns between vertical artificial seawalls and natural rocky shores in Victoria Harbour, Hong Kong. Included in the study are three vertical artificial seawalls and three natural rocky shores. Findings revealed that the chiton Acanthopleura japonica and the oyster Saccostrea cucullata and barnacle Amphibalanus were abundant in artificial seawalls while natural rocky shores supported a greater abundance of the false limpet Siphonaria laciniosa and the barnacle Tetraclita squamosa. The authors attributed the differences in zonation patterns of species to the vertical orientation of artificial seawalls.

Summary 1. Competitive interactions within and between size-classes of the limpet Patella depressa Pennant were investigated in central Portugal. Experimental enclosures of 25 × 25 cm containing marked limpets were set up at mid-tidal level on the shore. Twelve treatments with different combination of densities and size-classes were assigned to the plots, with three replicates of each. Mortality was recorded every 15 days and length was measured monthly during the approximately 6 months of the experiment. 2. At the end of the experiment limpets were collected for determination of length, height, dry weight, sex and gonad development. The availability of food was assessed indirectly by determination of chlorophyll concentration with spectrophotometric analysis of rock chips. Reduced density treatments showed very low mortality and substantially increased growth. Both size-classes of limpets showed increased mortality and reduced growth in increased density treatments. This effect was, however, more marked for large than small limpets when caged separately. 3. Although both size-classes could negatively affect each other, the effect of large limpets on small was greater than the reverse. Large limpets are superior competitors that may modulate the abundance of small limpets on the shore. It is unlikely, however, that they will totally exclude small limpets due to intensity of competition within the large size-class. Niche differentiation and high recruitment at low shore levels are other possible factors that can contribute to reduce competition between the size-classes. [ABSTRACT FROM AUTHOR]

Inter- and intraspecific competitive interactions among the species Patella depressa Pennant and P. vulgata L. were analysed on the northern coast of Portugal, where both species co-occur in similar proportions. Increased (×2, ×4), normal and decreased (×1/2 intraspecific only) densities of limpets were used to test the effects of competition on the growth and mortality of the limpets, and competitive interactions between the different species. Fenced plots of 25×25 cm enclosing marked limpets at various densities were set up at a mid tidal level on the shore. Twelve treatments with three replicates of different combinations of densities and species were established. Mortality was recorded every 15 days and length was measured monthly during the 5 months of the experiment. At the end of the experiment, limpets were collected for biometry, sex determination and gonad staging. Both species of grazing molluscs showed increased mortality and reduced size and weight in increased density treatments. Limpets in decreased density treatments showed lower mortality and higher size. There were no significant differences between the effect of P. vulgata on P. depressa and the effect of P. depressa on P. vulgata on mortality and length. There were, however, decreases in weight due to intraspecific effects for both species. For P. vulgata, interspecific effects were much less than intraspecific effects and for P. depressa, the interspecific effects depended on density. The analysis of the gonad stage at the end of the experiment showed that the lower stages of development were most prevalent at increased densities and the occurrence of neuter individuals only in increased densities single species plots corroborated the evidence of a stronger intraspecific interaction. The availability of food was indirectly assessed by determination of chlorophyll concentration with spectrophotometric analysis of rock chips. Microalgal food assessment in this experiment, however, did not show any clear trends. The results were compared with previous studies of competition in grazing molluscs and discussed in relation to the limits of distribution of P. vulgata on the Portuguese coast. [Copyright &y& Elsevier]

Nowadays, coastal urbanization is one of the most serious and prevalent pressures on marine ecosystems, impacting their biodiversity. The objective of this study was to explore differences in attributes and biodiversity associated with an intertidal ecosystem engineer, the mussel Mytilus galloprovincialis Lamarck, 1819 between urban and non-urban shores. For this, mussel attributes and their associated macrofauna were compared between urban and non-urban rocky shores in the north of Portugal. Results showed that the largest sized mussels were more frequent on urban shores, whereas the smallest size class was only present in non-urban shores. Regarding macrofauna associated with mussels, the number of taxa was significantly higher on non-urban shores. Moreover, the structure of the macrobenhic assemblages was significantly different between urban and non-urban shores. Most important taxa responsible for differences were more abundant on non-urban shores except for Nucella lapillus, Idotea pelagica and Oligochaeta that were more abundant on urban shores. Therefore, our results showed that the mussel size frequency and the structure of the associated macrobenthic assemblages changed in urban shores. Considering the relevance of mussel beds for biodiversity and human well-being, our results indicate the need of adopting proper management plans to minimize these effects on urban intertidal ecosystems. [ABSTRACT FROM AUTHOR]

Highlights: [•] Distribution of the invasive Undaria pinnatifida in Portugal. [•] Distribution models of Undaria pinnatifida does not fit with field observations. [•] Absence of Undaria pinnatifida in north Portugal despite the favourable conditions. [•] New records of Undaria pinnatifida in central Portugal. [ABSTRACT FROM AUTHOR]

Mediterranean coastal ecosystems experience many local and global stressors and require long-term monitoring to detect and follow trends in community structure. Between 2009 and 2017, we seasonally and annually monitored the spatiotemporal community dynamics at 11 sites on the rocky shores of the southeastern Mediterranean, focusing on the understudied intertidal vermetid reef ecosystem. Marked seasonal trends were found in biodiversity, with the highest diversity in winter and spring. Canopy-forming brown algae, dominating the northwestern Mediterranean intertidal reefs, were generally scarce on the reef platform and almost only found in tidepools. Interannual shifts in community structure were driven mostly by sharp fluctuations in a few dominant native and alien species and the regional mass mortality of an Indo-Pacific mussel in summer 2016. Compared to an older macroalgae dataset, dating back to 1973–1995, we found that some warm-affinity (summer) taxa became more dominant and cold-affinity (winter) species less dominant, while one once conspicuous species, Halimeda tuna , completely disappeared. The observed community shifts are probably driven mostly by stressors related to climate change. We encourage forming a network of long-term, multi-site ecological monitoring programs in the Mediterranean to improve our understanding of ecosystem change and to enable making better predictions at the basin scale. • Levant vermetid reefs long-term monitoring revealed strong community shifts. • Seasonality is strong and winter-spring periods were more diverse than summer-fall. • Canopy-forming brown algae were scarce on the reefs. • The alien mussel Brachidontes pharaonis population rapidly collapsed in summer 2016. • Some characteristic summer taxa become more dominant, and winter ones - less dominant. [ABSTRACT FROM AUTHOR]