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Amphiboreal taxa are often composed of vicariant phylogroups and species complexes whose divergence and phylogeographic affinities reflect a shared history of chronic isolation and episodic trans-Arctic dispersal. Ecological filters and shifting selective pressures may also promote selective sweeps, niche shifts and ecological speciation during colonization, but these are seldom considered at biogeographical scales. Here we integrate genetic data and Ecologic Niche Models (ENMs) to investigate the historical biogeography and cohesion of the polymorphic rockweed Fucus distichus throughout its immense amphiboreal range, focusing on trans-Arctic asymmetries, glacial/interglacial dynamics, and integrity of sympatric eco-morphotypes. Populations were sampled throughout the Pacific and the Atlantic, from southern rear-edges to the high-Arctic. They were genotyped for seven microsatellites and an mtDNA spacer, and genetic diversity and structure were assessed from global to local scales. ENMs were used to compare niche divergence and magnitude of post-glacial range shifts in Pacific versus Atlantic sub-ranges. Haplotypic and genotypic data revealed distinct and seemingly isolated Pacific vs Arctic/Atlantic gene-pools, with finer-scale regional sub-structuring pervasive in the Pacific. MtDNA diversity was highly structured and overwhelmingly concentrated in the Pacific. Regionally, Alaska showed the highest intra-population diversity but the lowest levels of endemism. Some sympatric/parapatric ecotypes exhibited distinct genotypic/haplotypic compositions. Strikingly, niche models revealed higher Pacific tolerance to maximum temperatures and predicted a much more consolidated presence in the NE Atlantic. Glacial and modern ranges overlapped extensively in the Pacific, whereas the modern Atlantic range was largely glaciated or emerged during the Last Glacial Maximum. Higher genetic and ecogeographic diversity supports a primary Pacific diversification and secondary Atlantic colonization, also likely reflecting the much larger and more stable climatic refugia in the Pacific. The relic distribution and reduced ecological/morphological plasticity in the NE Atlantic are hypothesized to reflect functional trans-Arctic bottlenecks, recent colonization or competition with congeners. Within the Pacific, Alaska showed signatures of a post-glacial melting pot of eastern and southern populations. Genetic/ecotypic variation was generally not sufficiently discontinuous or consistent to justify recognizing multiple taxonomic entities, but support a separate species in the eastern Pacific, at the southern rear-edge. We predict that layered patterns of phylogeographic structure, incipient speciation and niche differences might be common among widespread low-dispersal amphiboreal taxa.

Intertidal environments are highly dynamic and exhibit both regular and periodic fluctuations in environmental parameters. The interplay of these parameters controls the distribution and abundance of infaunal organisms resulting in sporadic bioturbation distributions that are well‐documented but not fully understood. This study investigates topographic controls on infaunal distributions at East Beach in White Rock, British Columbia, Canada. East Beach is a sandy intertidal flat characterized by sand dunes that give rise to two alternating shore‐parallel subenvironments: topographically high dune crests and topographically low interdunes. The dunes remain relatively fixed in their position between major storm events, resulting in geographically stable subenvironments. Photogrammetric reconstructions of dune surfaces are used to characterize surface features and quantify invertebrate burrow openings along dune profiles. This is supplemented by X‐ray radiography and examinations of porewater and organic matter content from the two subenvironments. These results show a clear inverse relationship between burrow abundance and elevation at the dune scale, with the interdunes displaying significantly higher bioturbation intensities compared to dune crests. The burrow distributions appear to be strongly influenced by water saturation, presumably due to its role in controlling oxygen availability and preventing desiccation. This research provides insights into the local factors controlling infaunal distributions and the impact of palaeo‐topography on bioturbation, particularly in intertidal settings. Additionally, these data assist in interpreting heterogeneous bioturbation distributions in the sedimentary record, which are normally not interpreted due to a paucity of analogue models developed in modern environments. [ABSTRACT FROM AUTHOR]

The morphology of the zoeae I, II and III of Alpheus cf. packardii was described based on laboratory-hatched larvae. Parental female was captured at Ubatuba bay, north coast of São Paulo, Brazil. The morphological characteristics of the species were compared with descriptions of other Alpheus species with known first zoeal stages. The zoea I of A. cf. packardii differs from the other 27 species through: coxal endite of maxillule with 6 (4 simple, and 2 sparsely plumose) setae; basal endite with 2 stout spines, 1 small plumose setae and 1 small simple setae; coxal endite of maxilla not bilobed, with 2 long sparsely plumose setae; basal endite bilobed, proximal lobe 2 simple and 1 sparsely plumose setae, distal lobe with 2 simple setae and 1 sparsely plumose setae, both with one terminal protuberance; second maxilliped with endopod 4-segmented, 1 terminal simple, 0, 1 terminal serrate, 5 (1 proximal and 3 terminal simple, plus 1 terminal serrate) setae. Considering the importance of the identification of larval forms in the natural environment, our results can be used in a larval identification key and help to advance research on areas such as ecological distribution of early post-embryonic stages in the meroplankton community. [ABSTRACT FROM AUTHOR]

Colonisation of novel habitats are important events in evolution, but the factors that initially prompt such ecological transitions are often unknown. The invasion of land by fish is an extreme habitat transition that offers an opportunity to empirically investigate the causes of major ecological transitions. The intertidal ecotone—and rock pools in particular—have been an important staging ground for transitions onto land. Classic hypotheses focus on the adverse abiotic conditions of rock pools at low tide as the instigator of fish voluntarily stranding themselves out of water, which can then lead to the evolution of an amphibious lifestyle. To test these hypotheses, we studied the abiotic conditions of 54 rock pools on the island of Guam where there are various species of aquatic, amphibious and terrestrial blenny fishes. We found little support for the expected deterioration of abiotic conditions in standing pools at low tide (salinity, pH and oxygen), and fish were not seen to be excluded from those pools that were found to exhibit poor abiotic conditions (temperature, salinity and pH). Hypoxia was the only factor that might account for the absence of blennies from certain rock pools. Next, we experimentally measured oxygen depletion by an aquatic, mildly amphibious and highly amphibious species of blenny found on Guam in a simulated rockpool to infer the proportion of rock pools at low tide outside the tolerable range of blennies. Rock pools were found to have oxygen levels within the requirements of most blennies and those of other marine fishes reported in the literature. We conclude that the abiotic environment of rock pools alone was unlikely to have instigated the evolution of amphibious behaviour in blennies, at least on Guam. Instead, the broad range of abiotic conditions experienced in rock pools suggests these conditions could have primed amphibious blennies to better endure the novel conditions on land. Any ecotone typified by fluctuations or gradients in abiotic conditions is likely a key transitional environment for the invasion of novel habitats and, as such, are an important location for adaptive evolution and species diversification. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

The availability of online biodiversity data has increased in recent decades, aiding our understanding of diversity patterns and species richness–environment relationships across temporal and spatial scales. However, even the most exhaustive databases are prone to sampling biases, which create knowledge gaps in species distributions and increase uncertainty in model predictions. Regarding marine environments, intertidal zones are globally distributed and considered early warning systems for climate change impacts and species' range shifts. Owing to their relative accessibility, intertidal records should – supposedly – be less incomplete and biased compared to open‐ocean and deep‐sea areas. Yet, the extent and coverage of intertidal records available in global biodiversity databases remains unknown. In this study, we used a high‐resolution worldwide tidal flat map to identify intertidal records of 11 563 benthic species from the OBIS (Ocean Biodiversity Information System) portal. Following a thorough data‐cleaning process, we evaluated geographic patterns in observed species richness, site accessibility, sampling effort, and inventory completeness across latitudes. We demonstrate that observed species richness has mid‐latitudinal peaks while the tropics accumulate species with missing records, similar to patterns described for the entire marine realm. These patterns correlate with disproportionate mid‐latitude sampling efforts and poor tropical sampling coverage. Sixty‐five percent of the mapped intertidal sites are located within 3 hours of a city, but sampling records remain almost absent along African Atlantic, South American Pacific, and Indo‐Pacific coasts. Thus, even for the accessible and well‐studied intertidal shorelines, database records are not free from geographical biases and their associated implications for biodiversity estimates. Our results highlight the need for a better data‐sharing culture, and we hope to encourage initiatives promoting more and better‐distributed research efforts on intertidal biodiversity, which could improve global scale detection and prediction of climate change impacts at regional and global scales. [ABSTRACT FROM AUTHOR]

The factors shaping host–parasite interactions and epibiont communities in the variable rocky intertidal zone are poorly understood. California mussels, Mytilus californianus , are colonized by endolithic cyanobacterial parasites that erode the host shell. These cyanobacteria become mutualistic under certain abiotic conditions because shell erosion can protect mussels from thermal stress. How parasitic shell erosion affects or is affected by epibiotic microbial communities on mussel shells and the context dependency of these interactions is unknown. We used transplant experiments to characterize assemblages of epibiotic bacteria and endolithic parasites on mussel shells across intertidal elevation gradients. We hypothesized that living mussels, and associated epibacterial communities, could limit colonization and erosion by endolithic cyanobacteria compared with empty mussel shells. We hypothesized that shell erosion would be associated with compositional shifts in the epibacterial community and tidal elevation. We found that living mussels experienced less shell erosion than empty shells, demonstrating potential biotic regulation of endolithic parasites. Increased shell erosion was not associated with a distinct epibacterial community and was decoupled from the relative abundance of putatively endolithic taxa. Our findings suggest that epibacterial community structure is not directly impacted by the dynamic symbiosis between endolithic cyanobacteria and mussels throughout the rocky intertidal zone. [ABSTRACT FROM AUTHOR]

Contemporary symbioses in extreme environments can give an insight into mechanisms that stabilize species interactions during environmental change. The intertidal sea anemone, Anthopleura elegantissima, engages in a nutritional symbiosis with microalgae similar to tropical coral, but withstands more intense environmental fluctuations during tidal inundations. In this study, we compare baseline symbiotic traits and their sensitivity to thermal stress within and among anemone aggregations across the intertidal using a laboratory‐based tank experiment to better understand how fixed genotypic and plastic environmental effects contribute to the successful maintenance of this symbiosis in extreme habitats. High intertidal anemones had lower baseline symbiont‐to‐host cell ratios under control conditions, but their symbionts had higher baseline photosynthetic efficiency compared to low intertidal anemone symbionts. Symbiont communities were identical across all samples, suggesting that shifts in symbiont density and photosynthetic performance could be an acclimatory mechanism to maintain symbiosis in different environments. Despite lower baseline symbiont‐to‐host cell ratios, high intertidal anemones maintained greater symbiont‐to‐host cell ratios under heat stress compared with low intertidal anemones, suggesting greater thermal tolerance of high intertidal holobionts. However, the thermal tolerance of clonal anemones acclimatized to different zones was not explained by tidal height alone, indicating additional environmental variables contribute to physiological differences. Host genotype significantly influenced anemone weight, but only explained a minor proportion of variation among symbiotic traits and their response to thermal stress, further implicating environmental history as the primary driver of holobiont tolerance. These results indicate that this symbiosis is highly plastic and may be able to acclimatize to climate change over ecological timescales, defying the convention that symbiotic organisms are more susceptible to environmental stress. [ABSTRACT FROM AUTHOR]

With the ongoing climate and oceanographic change, an increasing number of studies are reporting dramatic population losses caused by thermal extremes in intertidal habitats. Under moderate warming, however, populations can fare better in places where species normally experienced suboptimal temperatures. This article reports the massive recruitment of the barnacle Semibalanus balanoides on the Gulf of St. Lawrence coast of Nova Scotia (Canada) in 2024. As recruits appear mostly during May in this region, coastal sea surface temperature (SST) in April is critical for the ecological performance of larvae, as they are pelagic and live in the water column for weeks before intertidal settlement. Thus, a study that spanned 12 years (2005 to 2016) on this coast found that annual barnacle recruitment was positively correlated to April SST. In April 2024, coastal SST was 116% higher than for the same month averaged over those 12 years (4.1 vs. 1.9 °C). This SST spike was followed by an elevated recruitment that was 111% higher than the average for those 12 years (1,278 vs. 607 recruits dm−2). Overall for the studied years, the amount of variation in annual barnacle recruitment statistically explained by April SST was 51%. While the southern distribution limit of S. balanoides has moved northwards in recent decades due to lethal warming, our results support the notion of improving reproductive success with seawater warming on colder northern shores. [ABSTRACT FROM AUTHOR]

Dwarf eelgrass, Zostera noltii, is an important ecosystem engineer that creates dense meadows along the coasts of Europe and Northwest Africa. During the last century, this seagrass species suffered severe population declines, and to counteract these losses, restoration has emerged as an important management tool. Thus far, restoration efforts with Z. noltii have only been performed with shoot‐ and core‐based methods, which are challenging to upscale sustainably.Here, we explored if Z. noltii can be restored with seeds, thus potentially offering an upscalable solution for future restoration efforts. With the newly developed dispenser injection seeding (DIS) method, we tried seed‐based Z. noltii restoration in the intertidal Wadden Sea. With a field experiment, we investigated how seeding depth (1.5 and 3 cm) and seed amount (5, 10 and 20 seeds/injection) affected Z. noltii recruitment success and efficiency.Most importantly, our results show that Z. noltii can be restored with seeds, as 3 months after seeding, 184 individual patches had emerged from our 7000 seeds (2.6% recruitment). Recruitment success (number of restored patches/plot) was enhanced by higher seed amounts (20 > 5 seeds/injection), while the opposite was true for recruitment efficiency (number of restored patches/seed), which was reduced by higher seed amounts (20 < 5 seeds/injection). Restored Z. noltii survived the first winter in all experimental plots, but seagrass cover (square metre/plot) reduced in two‐thirds of the plots compared to the first growing season.In conclusion, our findings show the potential of seed‐based Z. noltii restoration and provide insights on how upscaling of restoration efforts for this species can be performed more efficiently and sustainably in the future. [ABSTRACT FROM AUTHOR]

As a consequence of anthropogenic activities and climate change, accelerated terrestrial sediment runoff is causing the gradual mudification of soft sediment estuarine habitats worldwide. Increased sediment mud content (< 63 µm) has been recognised to alter seagrass morphology and cause declines in primary production in unvegetated habitats. However, the effect of increased mud content on primary production in seagrass meadows remains largely unknown. To address this, primary production in intertidal seagrass meadows (Zostera muelleri) and adjacent unvegetated habitats was measured in situ using benthic incubation chambers across an existing sedimentary gradient (nine sites spanning 5–33% mud content). An additional two unvegetated mudflat sites (39–49% mud content) were also sampled to expand the gradient. Seagrass net (NPP) and gross primary production (GPP) was greater than in the adjacent unvegetated habitat and did not vary with mud content, even after standardising GPP by photosynthesising biomass (i.e. photosynthetic efficiency). In contrast, in the adjacent unvegetated habitat, photosynthetic efficiency declined with increasing mud content. Inclusion of the additional mudflat sites negatively impacted NPP, GPP, and photosynthetic efficiency in the unvegetated habitat. Thus, while primary production in seagrass meadows may have some resilience to future increases in mud content (up to ~33%), further degradation and loss of seagrass habitats could result in the expansion of unvegetated habitats and ultimately lead to production losses, likely to be most acute in areas with high mud content (≥ 39%). [ABSTRACT FROM AUTHOR]

Seaweed aquaculture is becoming increasingly important as the global seaweed market is set to exceed £20 billion by 2030, leaving natural populations at risk of overexploitation. Fucoids, such as Fucus serratus, are intertidal seaweeds hand-harvested for their use in agricultural, pharmaceutical, and biomedical industries. Despite many aspects of the biology of fucoids being well researched, there have been very few studies on their aquaculture. In this study, we grew F. serratus biomass from gamete life stages in the Queen’s University Marine Laboratory for 8 months and monitored their growth, amino acid and phenolic contents in a subtidal field trial. Gametes of F. serratus were successfully fertilized in vitro and attached to substrata: Tiles (mesocosm) and Dyneema Twine (subtidal). The growth of F. serratus on each substrate was monitored for 6 months in the laboratory facility with juveniles reaching 2–4 mm in length. The juveniles on twine were then deployed at the Strangford Lough test site and growth was compared against the juveniles on tiles after an additional two months. Prior to field deployment, individuals grown on tiles were significantly longer (~17%) than those on twine growing to ~3 cm, however, after the two-month deployment, the twine thalli grew significantly longer than those on the tiles (~33%) reaching ~6 cm in length. Subtidal F. serratus grown on twine had significantly higher amino acid content, whereas the phenolic content was significantly lower (~62 mg PGE g−1) than seaweed grown on the tiles (~128 mgPGE g−1). Growing F. serratus successfully in subtidal areas is highly important for providing sustainably sourced biomass to reduce reliance on wild harvesting. Further, cultivating in the subtidal zone will help to avoid competition for space from other aquaculture industries operating in the intertidal zone.

ABSTRACT Hurricanes are natural periodic events that disrupt marine ecosystems along their path, altering the distribution and abundance of organisms. In October 2016, Hurricane Matthew struck the Santa Marta region (Colombia) and impacted its coastal zone, yet there have been insufficient studies to measure its effects. The aim of this study was to assess the impact of Hurricane Matthew on the meiofaunal community in the region. To achieve this, sediment samples were collected from the intertidal zone of three beaches 5 days after the hurricane had passed. The results were compared with previous data collected in October 2014, on the abundance and diversity of taxonomic groups of intertidal meiofauna, as well as physicochemical variables such as granulometry, organic matter in sediments, salinity, and water temperature. Following Hurricane Matthew, the physicochemical variables showed changes due to the effect of the cyclonic surge in the coastal zone. The average organism abundance not only experienced a decline in both abundance and richness but also underwent changes in composition. Nematoda, originally the fourth most abundant group in 2014, became the most dominant taxon post‐hurricane. Conversely, the relative abundance of Copepoda decreased. The total number of recorded taxa was 13, which is close to the 15 previously reported. The ANOSIM and PERMANOVA tests confirmed differences in the meiofaunal community before and after Hurricane Matthew, with Tardigrada, Cnidaria, Ostracoda and Mollusca, being the main groups that contributed the most to the dissimilarity between periods. The environmental variables of organic matter and temperature best explained the structure of the meiofaunal community after the natural phenomenon. This study highlights the importance of meiofauna as a monitoring tool for beaches and the effects of environmental disturbances such as hurricanes, which are expected to become more common in coastal areas due to climate change. [ABSTRACT FROM AUTHOR]

ABSTRACT Free‐living marine nematodes play crucial roles in the benthic ecosystem and serve as valuable bioindicators for monitoring environmental stress. We explore the community structure of free‐living marine nematodes in the beach ecosystem near Bandar Abbas port city of Iran. The research focused on assessing the impact of domestic and industrial influences during winter and summer seasons in 2018 and 2019. Three coastal locations, namely KhurGursuzan (KG), Power Plant (PP), and Resalat (RE), were sampled, with KG under domestic wastewater influence, PP characterized by industrial activities, and RE serving as the control site. A total of 41 nematode genera were identified during the study, and dominant genera varied across locations, namely, Daptonema, Sabatieria, Promonhystera, Ptycholaimellus, and Eleutherolaimus at KG; Spirinia, Chromadorina, Terschellingia, Eleutherolaimus, and Promonhystera at PP; and Oncholaimus, Pomponema, Viscosia, Ptycholaimellus, Daptonema, and Eleutherolaimus at RE. These dominant genera accounted for 80% of the total nematode community during the sampling periods. The study revealed significant differences in abundance and genus diversity among the sites, with pollution‐affected sites exhibiting the lowest nematode diversity. Sediment granulometry showed a positive correlation with genus diversity across the sites, and the structure of the nematode assemblage was negatively influenced by polychlorinated biphenyls and total organic matter. Surprisingly, the spatial patterns in nematode assemblage structure and diversity remained consistent across both studied years. These findings contribute to our understanding of marine ecosystem health and the role of free‐living nematodes as bioindicators in the Persian Gulf. [ABSTRACT FROM AUTHOR]

This study aims to report the diversity of the Halimeda genus on the West Aceh coast. Data was collected in the Lhok Bubon Coastal intertidal area, Samatiga, West Aceh Aceh Province. Macroalgae samples were collected using the cruising method along the beach with a depth of 1-2 m at low tide. The Halimeda genus found four species, namely Halimeda macroloba, Halimeda macrophysa, Halimeda incrassata, and Halimeda simulans. Halimeda macroloba was found to have a whitish-green talus. Halimeda macrophysa samples have irregular talus branches. Description Halimeda incrassata at the study site is light green, and the holdfast is attached to the sandy substrate to form large sediment clumps. Halimeda simulans were found to be linked to sand, which tends to have a finer texture. The results of this report provide information that Lhok Bubon Beach, West Aceh, has macroalgae potential that needs further study. [ABSTRACT FROM AUTHOR]

Light availability and habitat complexity are two key drivers of community assembly. Urbanisation has been shown to affect both, with important consequences to ecological communities. On the intertidal, for instance, studies have shown that light intensity is greater on natural rocky shores than on less complex artificial habitats (seawalls), though different habitats can also experience similar light intensities, for example when shaded by urban structures. Understanding therefore how these factors individually, and combined, affect communities is important to understand the mechanisms driving changes in community structure, and consequently provide solutions to tackle the increasing homogenisation of habitats and lightscapes in urbanised spaces through smart infrastructure designs. Here, we assessed how different light levels affect the recruitment of communities in rock pools and on emergent rock on an intertidal rocky shore. We cleared 30 patches of emergent rock and 30 rock pools and manipulated light using shades with different light transmissions (full light, procedural control, 75%, 35%, and 15% light transmission, full shade) and assessed mobile and sessile communities monthly for 6 months. Effects of reducing light levels were generally stronger on rock than in pools. Fully shaded plots supported double the amount of mobile organisms than plots in full sunlight, in both habitats. Algal cover was higher in pools compared to rock, and at intermediate light levels, but effects varied with site. This study highlights the importance of variable light conditions and different habitats for rocky shore communities, which should be considered in future coastal developments to retain natural biodiversity. [ABSTRACT FROM AUTHOR]

Mussels (Mytilus spp.) are abundant in the North Atlantic, sessile, and sensitive to environmental change, and suitable as sentinels of environment and climate change of costal ecosystems. We aimed to determine the baseline for the Northeast Atlantic (58–70°N) Mytilus species complex, and to show the present distribution to surveys conducted 60 years ago. Baseline was obtained by investigating a total of 509 stations in the intertidal zone, in four regions comprising the environmental gradient from head of fjord to coast, and distributed over the latitudinal gradient from 58 to 70°N. The baseline shows a range in continuous abundance of mussels from 12% to 36%, patchy abundance from 26% to 57% and no or very limited mussel abundance from 26% to 46% between the four regions. The presence of mussels in the southeast and west region was visualized to previous surveys conducted 60 years ago. The data points to similar past and present presence of mussels in both regions, yet past major mussel fields in the inner section of region southeast was not detected in this study. The baseline of Mytilus spp. in the Northeast Atlantic (58–70°N) is now available for future reference. The baseline, plotted to surveys conducted 60 years ago, points to awareness of the population situated in the southeast section of the investigated region. Continued monitoring and modeling are needed to clarify drivers of temporal and spatial variation in the mussel populations along the Northeastern Atlantic coast. [ABSTRACT FROM AUTHOR]

The fundamental ecological niche is determined by individuals' ability to cope with abiotic conditions; however, biotic interactions (e.g., competition) can also influence species' distribution ranges, reducing the fundamental niche to the realized niche. Several species of the genera Clibanarius and Calcinus overlap in their distributions. The agonistically dominant Calcinus species inhabits mostly lower intertidal levels, while Clibanarius is more abundant in the abiotically demanding upper strata. Additionally, evidence of microhabitat competitive exclusion shows that the superior competitor, Ca. californiensis, causes the vertical displacement of Cl. albidigitus. However, it is unknown whether competitive exclusion between species of these genera has influenced their distributions at the macroecological scale. We used ecological niche models to compare the distribution and the habitat suitability of species of these genera. We used databases of species occurrences and bioclimatic and geophysical variables to model and map the species' niches. Species of the two hermit crab genera showed strong overlap in their habitat suitability. Calcinus and Clibanarius species occur in broad sympatry at the regional scale without regions of partial overlap that would indicate competitive exclusion. Therefore, competitive exclusion among species of these genera seems to act only on a microhabitat scale in the most dynamic shoreline areas. [ABSTRACT FROM AUTHOR]

In February 2023, a severe cold snap took place in Atlantic Canada and was followed by the mass loss of mussels at mid-to-high intertidal elevations on the southeastern Nova Scotia coast. This loss was concerning because mussels sustain upper trophic levels in coastal food webs and because mussel stands enhance local biodiversity by sheltering many small invertebrate species. Using photographs taken in the second summer after that cold snap (July 2024), this article provides visual evidence of active ongoing recolonization of intertidal mussels on this coast, including the incipient formation of new stands. These are encouraging signs of ecological resilience. Reaching historical values of abundance will likely depend on the future occurrence of weather extremes, which are becoming more frequent with the ongoing climate change. [ABSTRACT FROM AUTHOR]

Crabs are fundamental in coastal ecosystems due to their role in nutrient cycling, habitat structuring, population control and as indicators of environmental health. Investigating the size distribution and life stages of these species is crucial for understanding their ecology and designing effective conservation strategies. This study provides data on the distribution and stage ratios of two populations of local species of the genus Cyrtograpsus (Decapoda: Brachyura: Varunidae) in the Playa Cangrejales intertidal. These endemic species had not been previously described in the study area, highlighting the need for further research in the future. Three surveys were conducted from December 2019 to February 2020, following a transect perpendicular to the coast, obtaining two series of data (C‐I and C‐II). Specimens were identified, sexed and measured in situ for subsequent release. A total of 1099 individuals were counted, identifying Cyrtograpsus affinis (C‐I = 278; C‐II = 332) and Cyrtograpsus angulatus (C‐I = 215; C‐II = 277), with a higher proportion of C. affinis. The presence of these species at Playa Cangrejales coincides with the geographical distribution reported in the literature, although the proportions differ from those reported for other Argentinean beaches. The most frequent lengths were equal to or less than 10 mm cephalothorax length (±1 mm). The maximum lengths reported in the literature for each species were not recorded. For C. angulatus, juveniles always predominated over adults and recruits. C. affinis showed fluctuations between adult and juvenile proportions in the upper and middle zones, with adults predominating in the lower zone during December and February. Juveniles occupied all mesolittoral floors, whereas adults were more frequent in the middle and lower floors. This information is essential to develop management tools to protect these species and their environment. The division between stages was realized following criteria from the literature. Analyses and interpretations were made using data distribution and frequency graphs. [ABSTRACT FROM AUTHOR]

Understanding drivers of effort and catch is important for sustainable management of recreational fisheries. For the Pipi (Latona deltoides) fishery in South Australia as a case study, publicly available datasets on fisher demography, market forces and internet connectivity improved understanding of fisher motivations and capabilities, identified different historical periods in the fishery and addressed temporal gaps in effort and catch estimates from on‐site surveys. Most variables were correlated with recreational effort and catch estimates from on‐site surveys and principal component analysis identified 2013–2014, 2015–2018 and 2019–2022 as distinct periods in the Pipi fishery. Results corroborated studies and anecdotal information that suggested declining availability and higher prices of local, commercially caught Pipi, and reduced imports of bivalves from Asia that previously supplied the South Australian bait market. Reduced availability and higher prices of Pipi likely motivated recreational fishers to gather their own bait to increase catch over the years. Similarly, increased internet and smartphone access and increased numbers of utility vehicles aided recreational catch efficiency of Pipi. Effective management of recreationally harvested resources requires understanding of external processes that drive fisher motivations and capabilities, particularly for stocks that are shared among fisheries. The need for improved data on fisher behaviour for management of recreational fisheries can be addressed by leveraging external information from available datasets. We recommend that the temporal gap between surveys should be less than 5 years, supplemented by analysing behavioural information collected from fishers during interviews. [ABSTRACT FROM AUTHOR]

Benthic amphipod feeding groups are a well-established trophic classification that is mostly based on field observations and laboratory tests and are used in ecological studies to monitor the ecological state of benthic ecosystems. Globally, carbon and nitrogen stable isotope ratio investigations have provided confirmation of, and novel insights into, the trophic ecology of benthic animals, such as polychaetes. However, stable isotopic examinations of benthic amphipods have been limited. Here, we used microgram samples to compare the species-specific dietary sources, trophic positions, and isotopic niche overlap of selected benthic amphipods from the Gulf of Kachchh, Marine National Park, using elemental analyser-isotopic ratio mass spectrometry (EA-IRMS) of carbon and nitrogen. Overall, all primary carbon sources presented wide variation in the isotopic values of δ13C (6.3‰) and δ15N (greater than 13‰). Conversely, the amphipod taxa displayed relatively narrow range for δ13C (3.9‰) and wider range for δ15N (more than 10‰). The results of the Bayesian mixing model revealed that the benthic amphipods had species-specific feeding preferences. However, the predominant carbon source was organic matter in sediment which reinforced benthic pathways for energy flow for most species. According to the estimated trophic level values (1.62–3.39), these species play a significant role as primary and secondary consumers serving as crucial trophic intermediaries in the food chain, connecting the base to the top consumers. High overlapping ecological niche amongst species was detected by SIBER analysis which indicated co-existence of the benthic amphipods in their respective microhabitats. This signifies wider utilisation of resources and inter-specific feeding preferences with minimal competition amongst amphipod species. [ABSTRACT FROM AUTHOR]

Aratichnus, new ichnogenus, is described from a lower Eocene-aged, tidally reworked sandstone unit (Baronia Formation) near Baronia de Sant Oïsme, Spain. Aratichnus n. igen. is a horizontal, epichnial furrow ranging from simpler forms that display repeating straight to gently curved grooves to more complex serial furrows paralleling each other. Two new ichnospecies are described, Aratichnus hordeicollis n. isp. and Aratichnus apricuscampus n. isp., that encompass the range of morphological variability exhibited by the ichnogenus. A. hordeicollis exhibits ordered, repeating shapes of furrows, while A. apricuscampus exhibits furrows which do not repeat in shape and direction. We interpret Aratichnus n. igen. as a trace fossil made by an interface deposit feeder exploiting a patchy food source in an intertidal environment. [ABSTRACT FROM AUTHOR]

In the early summer of 2021, an intense heatwave killed millions of intertidal mussels in British Columbia, Canada. Using photographs taken three years later (June 2024), this article provides visual evidence of active recovery of intertidal mussel stands in the Vancouver region, revealing the resilience of these intertidal systems. Future monitoring should evaluate their ability for long-term persistence in light of the ongoing climate change, which is expected to increase the frequency and intensity of heatwaves. [ABSTRACT FROM AUTHOR]

Rocky intertidal habitats occur worldwide and are mainly characterized by primary space holders such as seaweeds and sessile invertebrates. Some of these organisms are foundation species, as they can form structurally complex stands that host many small invertebrates. The abundance of primary space holders is known to vary along coastlines driven directly or indirectly by environmental variation. However, it is less clear if the invertebrate assemblages associated to a foundation species may remain relatively unchanged along coastlines, as similar stands of a foundation species can generate similar microclimates. We examined this question using abundance data for invertebrate species found in mussel stands of a similar structure in wave-exposed rocky habitats at mid-intertidal elevations along the Atlantic coast of Nova Scotia (Canada). While the most abundant invertebrate species were found at three locations spanning 315 km of coastline, species composition (a combined measure of species identity and their relative abundance) differed significantly among the locations. One of the species explaining the highest amount of variation among locations (a barnacle) exhibited potential signs of bottom-up regulation involving pelagic food supply, suggesting benthic–pelagic coupling. The abundance of the species that explained the highest amount of variation (an oligochaete) was positively related to the abundance of their predators (mites), further suggesting bottom-up forcing in these communities. Overall, we conclude that species assemblages associated to structurally similar stands of a foundation species can show clear changes in species composition at a regional scale. [ABSTRACT FROM AUTHOR]

Intertidal animals deal with physical gradients daily that create stressful conditions across the shore. These physical gradients influence the physiological performance of organisms, requiring responses that may differ with height on the shore. We examined the respiratory response to aerial exposure in the invasive Asian shore crab Hemigrapsus sanguineus during periods of low tide emersion using two field experiments. The first experiment simultaneously measured respiration of individuals collected from different heights on the shore, which had therefore been emersed for different lengths of time. The second experiment measured respiration of individuals collected at different times from the same tidal height. Respiration rates of crabs in both experiments increased immediately after emersion, nearly doubling by and peaking at ~ 1.5 h of aerial exposure, before decreasing again over the next 1.5 h. These results suggest that the energetic cost of low tide exposure is greatest shortly after emersion during the first half of the typical low tide period, but then decreases thereafter. These respiration patterns facilitate the broad intertidal distribution of this species on rocky shores throughout its range. [ABSTRACT FROM AUTHOR]

Abundant clam populations provide ecosystem services and commercial and recreational shellfish harvests worldwide. Two non‐native clams (Manila clams, Ruditapes philippinarum; eastern soft‐shell clams, Mya arenaria) commonly populate mid‐intertidal zones of coarse‐sediment beaches in Washington State, USA. To better understand factors influencing their abundance, we used passive mid‐intertidal spat collectors to determine the density and distribution of clam recruits (150–500 μm shell length) at eight beaches spanning over 500 km and over two reproductive seasons (2016 and 2017). Cumulative seasonal recruitment (clams <500 μm) in 2016 and 2017 at +1.0 m MLLW ranged from 800 to 125,000 m−2 for Ruditapes philippinarum and 50–85,000 m−2 for M. arenaria, and did not differ by substrate type at small scales (gravel vs. crushed shell). At larger scales, different interannual recruitment patterns across sites did not dramatically shift the ranked order of highest and lowest recruitment sites. Cumulative recruitment tended to be lower at warmer sites, while timing of peak recruitment was not consistently related to temperature. Sites also differed in the relative recruitment of the two clam species, but most beaches had greater densities of R. philippinarum than M. arenaria at both recruitment and juvenile stages. Although recruitment densities differed by two orders of magnitude across sites, post‐settlement factors eliminated initial spatial variation within a year, dampening recruitment variability among these beaches that all contribute to commercial and recreational clam production. [ABSTRACT FROM AUTHOR]

Human impacts on ecosystems are resulting in unprecedented rates of biodiversity loss worldwide. The loss of species results in the loss of the multiple roles that each species plays or functions (i.e., ecosystem multifunctionality) that it provides. A more comprehensive understanding of the effects of species on ecosystem multifunctionality is necessary for assessing the ecological impacts of species loss. We studied the effects of two dominant intertidal species, a primary producer (the seaweed Neorhodomela oregona) and a consumer (the shellfish Mytilus trossulus), on 12 ecosystem functions in a coastal ecosystem, both in undisturbed tide pools and following the removal of the dominant producer. We modified analytical methods used in biodiversity-multifunctionality studies to investigate the potential effects of individual dominant species on ecosystem function. The effects of the two dominant species from different trophic levels tended to differ in directionality (+/-) consistently (92% of the time) across the 12 individual functions considered. Using averaging and multiple threshold approaches, we found that the dominant consumer-but not the dominant producer-was associated with ecosystem multifunctionality. Additionally, the relationship between abundance and multifunctionality differed depending on whether the dominant producer was present, with a negative relationship between the dominant consumer and ecosystem function with the dominant producer present compared to a non-significant, positive trend where the producer had been removed. Our findings suggest that interactions among dominant species can drive ecosystem function. The results of this study highlight the utility of methods previously used in biodiversity-focused research for studying functional contributions of individual species, as well as the importance of species abundance and identity in driving ecosystem multifunctionality, in the context of species loss.

With the ongoing climate and oceanographic change, an increasing number of studies are reporting dramatic population losses caused by thermal extremes in intertidal habitats. Under moderate warming, however, populations can fare better in places where species normally experienced suboptimal temperatures. This article reports the massive recruitment of the barnacle Semibalanus balanoides on the Gulf of St. Lawrence coast of Nova Scotia (Canada) in 2024. As recruits appear mostly during May in this region, coastal sea surface temperature (SST) in April is critical for the ecological performance of larvae, as they are pelagic and live in the water column for weeks before intertidal settlement. Thus, a study that spanned 12 years (2005 to 2016) on this coast found that annual barnacle recruitment was positively correlated to April SST. In April 2024, coastal SST was 116% higher than for the same month averaged over those 12 years (4.1 vs. 1.9 °C). This SST spike was followed by an elevated recruitment that was 111% higher than the average for those 12 years (1,278 vs. 607 recruits dm−2). Overall for the studied years, the amount of variation in annual barnacle recruitment statistically explained by April SST was 51%. While the southern distribution limit of S. balanoides has moved northwards in recent decades due to lethal warming, our results support the notion of improving reproductive success with seawater warming on colder northern shores.

Abstract Characterisation of genomic variation among corals can help uncover variants underlying trait differences and contribute towards genotype prioritisation in coastal restoration projects. For example, there is growing interest in identifying resilient genotypes for transplantation, and to better understand the genetic processes that allow some individuals to survive in specific conditions better than others. The coral species Pocillopora acuta is known to survive in a wide range of habitats, from reefs artificial coastal defences, suggesting its potential use as a starter species for ecological engineering efforts involving coral transplantation onto intertidal seawalls. However, the intertidal section of coastal armour is a challenging environment for corals, with conditions during periods of emersion being particularly stressful. Here, we scanned the entire genome of P. acuta corals to identify the regions harbouring single nucleotide polymorphisms (SNPs) and copy number variations (CNVs) that separate intertidal colonies (n = 18) from those found in subtidal areas (n = 21). Findings revealed 74,391 high quality SNPs distributed across 386 regions of the P. acuta genome. While the majority of the detected SNPs were in non-coding regions, 12% were identified in exons (i.e. coding regions). Functional SNPs that were significantly associated with intertidal colonies were found in overrepresented genomic regions linked to cellular homeostasis, metabolism, and signalling processes, which may represent local environmental adaptation in the intertidal. Interestingly, regions that exhibited CNVs were also associated with metabolic and signalling processes, suggesting P. acuta corals living in the intertidal have a high capacity to perform biological functions critical for survival in extreme environments.

There is much controversy surrounding factors that affect the distribution of mangrove plants across the intertidal gradient. It was previously hypothesized that mangrove zonation was attributed to tidal sorting (TSH) of its propagules according to size (weight) or differential ability of propagules to establish in deep water. However, observational and experimental evidence have provided little support for the actual mechanism(s) of mangrove zonation. In general, species distribution pattern is the consequence of propagule dispersal. The specific gravity of water-borne mangrove propagules may affect their buoyancy, with inherent links to dispersal, thereby potentially influencing tree zonation. Propagule specific gravity can influence the distribution of mangroves in the context of global change, particularly in response to changes in seawater salinity. In this study, we measured the specific gravity and weight of 35 mangrove species propagules. There was no correlation between the weight of the propagule and its specific gravity. The specific gravity of propagules of true mangrove species was significantly greater than that of semi-mangrove. The results of the correlation between propagule specific gravity and the relative surface elevation of field distribution support the hypothesis that propagules are subject to tidal sorting and are not related to weight but to specific gravity. This newfound understanding of mangrove dispersal and distribution is critical in the context of mangrove protection and restoration, especially in projecting the effects of anthropogenic activities and global change on mangrove communities. [ABSTRACT FROM AUTHOR]

Coastal biogenic structures, formed by ecosystem engineering species, often feature rough surfaces characterized by intricate topographies and highly threedimensional reliefs. Their surfaces are shaped by waves and tidal currents and reciprocally influence the ambient hydrodynamics, reflecting an equilibrium. Despite their significance, the impact of these surfaces on the ambient hydrodynamics remains underexplored due to limited knowledge of accurately replicating their complex topographies in experimental setups. The recent advent of advanced digital manufacturing presents an efficient means to manufacture highly complex, three-dimensional surrogate models for experimental modeling. This work explores the accurate replication of rough coastal biogenic structures for experimental modeling on the examples of an oyster reef and a mussel bed, utilizing a flexible design methodology and, for the first time, particle bed 3D printing with Selective Cement Activation (SCA) as a fabrication and manufacturing method. A workflow is proposed, which includes an iterative surrogate model development based on in-situ topographical features, requirements of the experimental setup, and parameters of the particle bed 3D printer with SCA. The results demonstrate the effectiveness of the methodology in achieving highly accurate surrogate surfaces of complex coastal biogenic structures by validation against a set of topographical features relevant to hydraulic roughness. Particle bed 3D printing with SCA proved to be a suitable method to manufacture complex surrogate surfaces for experimental modeling, offering advantages such as independence of production time from surface complexity. However, challenges persist in achieving exact comparability between the manufactured surrogate surface and the real coastal biogenic structures, particularly for surfaces with very high complexity. Nonetheless, the manufactured generic surrogate surfaces enable detailed investigations into the influence of complex coastal biogenic structures on the ambient hydrodynamics, thereby enhancing the understanding of the processes governing wave energy dissipation attenuation, turbulence production, and vertical mixing - critical for efficient application as a nature-based solution on coastal protection or restoration efforts. [ABSTRACT FROM AUTHOR]

Population outbreaks of zoantharians in shallow water reefs have been observed globally, including intertidal and subtidal sites in the Canary Islands. This study investigated how zoantharians might be integrating into the local trophic network. For that purpose, we assessed the feeding patterns of common species in zoantharian-dominated habitats, focusing on finding consumers of Zoanthus pulchellus and Palythoa caribaeorum. Through DNA-barcoding and metabarcoding, the gut contents of 11 predatory species were analysed, aiming to characterize their diets and explore local species feeding on zoantharians. Analyses of diet revealed a diverse range of food items and trophic positions of some of the most common and frequent marine species in the archipelago. Furthermore, based on previous observations on the different impacts of Z. pulchellus and P. caribaeorum on shallow benthic ecosystems of the Canary Islands, a preliminary approach to identify their potential influence on feeding patterns of associated species was made. Even though DNA-metabarcoding did not detect zoantharians in the gut contents of any studied species, Sanger sequencing with zoantharian-specific primers indicated their consumption by subject species may be limited to only the crab Platypodiella picta. In addition, by focusing on some of the most common species, this study enhances our understanding of the local trophic network and provides an insight into trophic dynamics in zoantharian-dominated habitats. [ABSTRACT FROM AUTHOR]

Long regarded to represent an undescribed species related to Sesarma reticulatum , warm-temperate populations of a common marsh crab from the Gulf of Mexico are herewith formally named Sesarma schubarti sp. nov. Records of S. reticulatum s. s. are restricted to the U.S. Atlantic seaboard from the Woods Hole region of Massachusetts to the Indian River region on the east coast of Florida. A diverse body of supportive evidence to underpin this separation has accrued over three decades, including previous observations based on physiology, ecology, reproduction, blood hemocyanin proteins, isozymes, and mtDNA sequences. Comparative morphological studies provide only minor structural characters to distinguish the new species from its Atlantic seaboard counterpart, including differences in the shape of the mature male first gonopod tip and positioning of a transverse crest on the male first pleonite. However, in fresh specimens colouration also differs, often strikingly so. Body surfaces that are variously purplish in mature specimens of S. reticulatum s. s., yielding the common name "purple marsh crab", are instead more commonly reddish to orange in S. schubarti sp. nov. Our analysis of new 16S and COI gene sequences, along with existing genetic data, clarifies relationships of the new species to both S. reticulatum s. s. and S. curacaoense. The new species is formally named in honor of the late Christoph D. Schubart, a cherished colleague who contributed extensively to knowledge of sesarmid and other brachyuran crabs over his unfortunately abbreviated career. [ABSTRACT FROM AUTHOR]

The impacts of individual restoration activities, such as the total area covered and specific actions taken, can be difficult to measure because they are typically not performed randomly or independently. In Puget Sound, Washington, United States, removal of hard armor is a primary shoreline restoration measure. The length of armor removed from a beach and additional restoration actions implemented can vary considerably. As such, it is challenging to attribute specific ecological responses to particular actions. We use an extensive collection of sites regularly monitored pre‐ and post‐restoration to explore the success of different extents of armor removal and three supplemental "living shoreline" restoration actions: native vegetation planting, log placement, and sediment supplementation ("nourishment"). We measured five ecological response variables: sediments (percent surface, subsurface gravel), beach logs (count, line width), beach wrack (percent cover, depth), riparian vegetation (percent cover of supratidal, backshore), and supratidal invertebrates (density, richness). Only beach logs were affected by the length of armor removed, whereas wrack increased regardless of length. Invertebrate abundance increased through time only when supplemental vegetation planting did not occur. Placement of logs post armor removal was an impactful supplemental restoration strategy, positively affecting not only the further accumulation of logs, but also the amount of wrack and gravel sediments. Sediment nourishment only affected the proportion of subsurface gravel, which decreased through time in nourished sites. We stress the importance of the thorough monitoring of the ecological effects of living shoreline restoration actions to better understand their role in ecosystem recovery through time. [ABSTRACT FROM AUTHOR]

Despite extensive studies on how environmental factors influence plant and soil nutrient distribution and stoichiometry, how the intertidal zone affects plant and soil distribution, and stoichiometry remains unclear. Therefore, this study analyzed the leaf and soil organic carbon (C), nitrogen (N), and phosphorus (P) concentrations and stoichiometry in mangrove forest wetlands in South China. The results demonstrated that leaf and soil phosphorus concentrations were significantly different in different plants and intertidal zones. The average leaf N:P ratio was 12.85 and was mainly nitrogen-limited. Soil organic carbon at 0-10 cm was higher in the mid- and low intertidal zones, while the opposite was true for the high intertidal zone. The nitrogen concentration at 0-10 cm was less than that at <30-40 cm in both the high and mid-intertidal zones, while the opposite was true for the low intertidal zone. The phosphorus concentration varied similarly to that of carbon. The C:N ratios at both 0-10 cm and 30-40 cm were the highest in the high intertidal zone and decreased with decreasing elevation. Contrastingly, the C:P and N:P ratios did not differ much among the three intertidal zones and between the 0-10-cm and 30-40-cm profiles. The soil C:N ratios significantly correlated with the leaf carbon, phosphorus, and C:P ratio. Overall, the results demonstrated that the soil stoichiometry responded differently to different plant communities and intertidal zones. These differences might be attributed to variations in the environmental conditions of plant communities. [ABSTRACT FROM AUTHOR]

Characterisation of genomic variation among corals can help uncover variants underlying trait differences and contribute towards genotype prioritisation in coastal restoration projects. For example, there is growing interest in identifying resilient genotypes for transplantation, and to better understand the genetic processes that allow some individuals to survive in specific conditions better than others. The coral species Pocillopora acuta is known to survive in a wide range of habitats, from reefs artificial coastal defences, suggesting its potential use as a starter species for ecological engineering efforts involving coral transplantation onto intertidal seawalls. However, the intertidal section of coastal armour is a challenging environment for corals, with conditions during periods of emersion being particularly stressful. Here, we scanned the entire genome of P. acuta corals to identify the regions harbouring single nucleotide polymorphisms (SNPs) and copy number variations (CNVs) that separate intertidal colonies (n = 18) from those found in subtidal areas (n = 21). Findings revealed 74,391 high quality SNPs distributed across 386 regions of the P. acuta genome. While the majority of the detected SNPs were in non-coding regions, 12% were identified in exons (i.e. coding regions). Functional SNPs that were significantly associated with intertidal colonies were found in overrepresented genomic regions linked to cellular homeostasis, metabolism, and signalling processes, which may represent local environmental adaptation in the intertidal. Interestingly, regions that exhibited CNVs were also associated with metabolic and signalling processes, suggesting P. acuta corals living in the intertidal have a high capacity to perform biological functions critical for survival in extreme environments. [ABSTRACT FROM AUTHOR]

A new species of the head-shield sea slug is described herein from an examination of the morphological and anatomical characters. A molecular analysis supported the novel status of the species. This species is named Melanochlamys droupadi n. sp. in the honour of the Hon'ble president of India, Shrimati (Mrs) Droupadi Murmu. It is the second species from the Indian region and the third true tropical species. All the specimens were collected from the Digha coast of West Bengal and the Udaipur coast of Odisha state, along the north-western Bay of Bengal. ZooBank registration number with the article number as: [ABSTRACT FROM AUTHOR]

Foundation species are spatially dominant species that increase habitat complexity and provide substrate and shelter for many smaller species. Through a mensurative field experiment, we tested the hypothesis that functional aspects of the associated communities are related to structural and functional properties of the foundation species. Specifically, we contrasted invertebrate communities living in mussel (Mytilus) and seaweed (Chondrus) stands from the same rocky intertidal environments in Atlantic Canada. Both stands reach similar heights above the substrate, but they differ structurally (rigid mussel shells vs. flexible seaweed fronds) and functionally (mussels generate biowaste while seaweeds offer food for herbivores). Our data supported the hypothesis in various ways. Detritivory (mostly by oligochaetes) was more prevalent in mussel stands, while herbivory was more prevalent in seaweed stands. Predators were mostly mites and, consequently, they were more prevalent in mussel stands, as mites eat oligochaetes. Functional traits related to body and mobility types were also related to properties of the foundation species. Overall, we conclude that structural and functional properties of foundation species can predict functional aspects of the associated communities. This concept may help to develop effective restoration strategies after the loss of foundation species due to anthropogenic factors. [ABSTRACT FROM AUTHOR]

The northern Chilean coast is characterized by its high productivity and diversity due to the presence of the cold, nutrient-rich water of the Humboldt Current. The coasts in the area are mainly bordered by rocky shores that provide many microhabitats for invertebrates. The aim of the present study was to analyse the spatial distribution of three sympatric intertidal decapods, Leptograpsus variegatus , Cyclograpsus cinereus and Petrolisthes granulosus , using probabilistic models. The studied locality was situated on the rocky shores of Taltal Bay, in the north of Chile. The counting of individuals could reveal the presence of the reported species, and if they did or did not coexist. The results revealed that L. variegatus and C. cinereus had a uniform pattern with Binomial distribition, whereas P. granulosus showed a random occurrence with Poisson distribution. These results would not coincide with classical observations of intertidal decapods on the rocky shores of continental Chile, as those denoted a gregarious pattern, but the distributions found would rather explain potential territorial behaviour. [ABSTRACT FROM AUTHOR]

Many shorebirds are long-distance migrants and they congregate on intertidal mudflats for feeding throughout their non-breeding season. Despite being one of the key staging sites for migratory shorebirds, data on shorebirds foraging ecology in Sarawak is insufficient for the understanding of the interaction between shorebirds and their behaviour. This study aimed to determine the foraging behaviour of Whimbrel (Numenius phaeopus), Bar-tailed Godwit (Limosa lapponica) and Terek Sandpiper (Xenus cinereus) at Asajaya and Buntal mudflats. Data collection of this study was conducted at low tide, during two non-breeding seasons with a total of 12 months of sampling. Focal observations were conducted within a 50 m × 50 m quadrat. A total of 8 exclusive foraging techniques were observed for the three shorebird species, including: pecking, probing, picking, stabbing, snapping, submerging, sweeping and ingesting. Terek Sandpiper displayed all the exclusive foraging behaviours, whereas Whimbrel and Bar-tailed Godwit showed 7 and 5 behaviours, respectively. The three shorebirds also displayed non-exclusive foraging behaviours such as walking, preening and defecating. Spearman correlation test indicates a positive correlation between the foraging behaviours performed among three shorebird species. All three shorebird species adopted similar mixed foraging strategies comprising pecking and probing, with an exception on supplementary behaviours observed in Whimbrel and Terek Sandpiper. Principal Component Analysis (PCA) analysis showed a strong correlation between picking and ingesting behaviours, suggesting a high chance of foraging success with the presence of picking behaviour. The outcome of this study is crucial in understanding how shorebirds maximise their behavioural performance when foraging as well as to assist in formulating better conservation strategies for targeted migratory shorebird species and coastal mudflats. [ABSTRACT FROM AUTHOR]

Blue mussels Mytilus have returned to the high Arctic region of Svalbard in the beginning of twenty-first century after being absent for almost a 1000 years. Not only M. edulis had arrived in Svalbard, but also a complex of sympatric species including M. edulis, M. galloprovincialis, M. trossulus, and some of their hybrids, which may have a wide range of origins from both sides of the North Atlantic. Mussels were first found in the sublittoral at the entrance to Isfjorden, west coast of Spitsbergen island, and are spreading in other areas, and recently were also found in the intertidal zone. Here, we report viable larvae that were recovered from within the mantle cavity of mussels from the lower intertidal shore collected in late July 2019 and 2021 in Trygghamna, Isfjorden. The identity of larval and adult mussels was confirmed by sequencing of barcode region. Larvae ranged in size from 178 to 376 µm, from mussels 21 to 57 mm in shell length, and estimated to range over 3 to 12 years. It remains unclear whether the larval retention within the mantle cavity results from an intake of near shore concentrations and whether this may lead to larviphagy. [ABSTRACT FROM AUTHOR]

Abstract Mussels (Mytilus spp.) are abundant in the North Atlantic, sessile, and sensitive to environmental change, and suitable as sentinels of environment and climate change of costal ecosystems. We aimed to determine the baseline for the Northeast Atlantic (58–70°N) Mytilus species complex, and to show the present distribution to surveys conducted 60 years ago. Baseline was obtained by investigating a total of 509 stations in the intertidal zone, in four regions comprising the environmental gradient from head of fjord to coast, and distributed over the latitudinal gradient from 58 to 70°N. The baseline shows a range in continuous abundance of mussels from 12% to 36%, patchy abundance from 26% to 57% and no or very limited mussel abundance from 26% to 46% between the four regions. The presence of mussels in the southeast and west region was visualized to previous surveys conducted 60 years ago. The data points to similar past and present presence of mussels in both regions, yet past major mussel fields in the inner section of region southeast was not detected in this study. The baseline of Mytilus spp. in the Northeast Atlantic (58–70°N) is now available for future reference. The baseline, plotted to surveys conducted 60 years ago, points to awareness of the population situated in the southeast section of the investigated region. Continued monitoring and modeling are needed to clarify drivers of temporal and spatial variation in the mussel populations along the Northeastern Atlantic coast.

Rocky intertidal habitats occur worldwide and are mainly characterized by primary space holders such as seaweeds and sessile invertebrates. Some of these organisms are foundation species, as they can form structurally complex stands that host many small invertebrates. The abundance of primary space holders is known to vary along coastlines driven directly or indirectly by environmental variation. However, it is less clear if the invertebrate assemblages associated to a foundation species may remain relatively unchanged along coastlines, as similar stands of a foundation species can generate similar microclimates. We examined this question using abundance data for invertebrate species found in mussel stands of a similar structure in wave-exposed rocky habitats at mid-intertidal elevations along the Atlantic coast of Nova Scotia (Canada). While the most abundant invertebrate species were found at three locations spanning 315 km of coastline, species composition (a combined measure of species identity and their relative abundance) differed significantly among the locations. One of the species explaining the highest amount of variation among locations (a barnacle) exhibited potential signs of bottom-up regulation involving pelagic food supply, suggesting benthic–pelagic coupling. The abundance of the species that explained the highest amount of variation (an oligochaete) was positively related to the abundance of their predators (mites), further suggesting bottom-up forcing in these communities. Overall, we conclude that species assemblages associated to structurally similar stands of a foundation species can show clear changes in species composition at a regional scale.

Whether more species are required to maintain ecosystem functioning as spatial scale increases or across environmental gradients has frequently been studied by examining whether different species drive ecosystem functioning in different sites. However, this approach does rule out the counterfactual scenario where a few species could potentially maintain ecosystem functioning across sites as this requires examining which species can (or cannot) compensate for the loss of others.Here, I used an observational study and a field‐based transplant experiment to examine the effects of species loss on biomass productivity in an intertidal marine macroalgal system. I calculated the number of species required to maintain biomass productivity across four depth zones reflecting a water emersion gradient using two commonly used observational approaches. Then, I combined hypothetical simulated extinction scenarios with field‐based transplant data of relative growth rates of all species across the four depth zones to explore how the number of species required to maintain biomass productivity across depth zones changed under counterfactual scenarios where species compensated for species loss.The observational analyses suggested that between three and four species were required to maintain productivity across the depth zones. The simulated extinction scenarios did not. Rather, decreases in biomass productivity due to the loss of some species (e.g. Fucus spiralis, Ascophyllum nodosum) were easily compensated by other species (e.g. Fucus vesiculosus). However, for some species like F. vesiculosus, the extinction simulations suggested that compensation would be unlikely.Commonly used observational approaches may overestimate the number of species required to maintain ecosystem functioning across environmental gradients and spatial scales. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Populations of the non-native Asian shore crab, Hemigrapsus sanguineus, now dominate the rocky intertidal of southern New England, USA. High abundances suggest the recent invader may have experienced enhanced success as a result of enemy release. While larvae and juveniles may serve as a food source for ecologically important species, little is known about predation of mature H. sanguineus or the influence of habitat on predation pressure. To assess natural predation rates of adult H. sanguineus, crabs were tethered in the intertidal at Clarks Cove in New Bedford, MA. Crabs were left in situ for half of a tidal cycle then observed for signs of predation. Results of separate high and low tide trials showed that adult crabs were preyed upon at both high and low tide, though at a significantly higher rate during high tide during both daytime and nighttime, suggesting predation by aquatic species is greater than that by terrestrial species. To investigate the role of habitat as refuge from predation, a laboratory experiment manipulated the complexity of habitat provided to crabs in the presence of a native fish predator. Results indicate better refuge is provided by more complex shelter. Together, findings suggest that fish, crabs, and/or diving birds are important predators for H. sanguineus in the invaded range and that habitat refuge acts to reduce predation pressure. [ABSTRACT FROM AUTHOR]

Bivalves such as oysters and clams have been farmed in intertidal zones across the Puget Sound region of the Salish Sea for thousands of years. The variety of gear types used on bivalve farms creates complex vertical structure and attachment points for aquatic epiphytes and invertebrates which increases habitat structural complexity, but may alter eelgrass cover in areas where bivalve farms and eelgrass meadows overlap. Eelgrass meadows are highly productive and ecologically foundational near shore habitats that provide valuable ecosystem services including the provision of nursery, refuge, and foraging habitat. Aquaculture has been a key feature of the environment in the Puget Sound for millennia, however, little is known about how well aquaculture practices are integrated into the system, and what services they provide to mobile species assemblages relative to unfarmed eelgrass meadows. We used stable isotope mixing models to estimate, for several species of near shore fish and crab in two areas of North Puget Sound, Washington, the percent diet originating from either a natural bottom habitat (eelgrass meadows), farm habitat (oyster farms), or pelagic planktonic sources. Our results indicate that several species of near shore fish such as surf perch and staghorn sculpin derive a significant proportion of their diets from farm areas, while crabs derive most of their diets from eelgrass habitat, and stickleback derive a significant proportion of their diets from planktonic sources. The results indicate that foraging habitat uses are species specific, and that several species that spatially overlap bivalve farms obtained a large percentage of their diets from adjacent bivalve farm habitat. [ABSTRACT FROM AUTHOR]

Knowing patterns and processes that govern macroinvertebrate distribution in sandy beaches becomes necessary in the framework of increasing human activities. Spatial patterns in sandy beaches are affected by daily changes in physical environmental conditions and species-specific features. Here, we assess the effect of daily changes on the spatial distribution along transects perpendicular to the waterline and habitat dispersion using Callichirus corruptus as a study model. Eleven sectors (urbanized and non-urbanized) were sampled on 6 beaches in southeastern Brazil, where ecological and biological information on this species was obtained. The spatial distribution of C. corruptus differed between the sampled sectors. However, higher density of burrows was observed in the intermediate portion, indicating aggregation in this zone. The burrow spatial dispersion index presented significant positive linear relationship with the size of saturated zones and the mean size of individuals. The spatial distribution of burrows was influenced by the sampling method, adequately represented by the gradient from low to the high tide mark in the intertidal zone. There was a strong clustering when burrows were counted along perpendicular transects to the shoreline, whereas a uniform distribution when burrows were counted in parallel transects. Aggregated patterns in the distribution of C. corruptus were observed in most of sampled beaches, highlighting the preference of the species for inhabiting the intermediate portion of the intertidal zone. Furthermore, other conditions that might additionally explain the spatial dispersion of macroinvertebrates in soft sediments and the effect of human activities on natural populations of sandy beaches remain to be explored. [ABSTRACT FROM AUTHOR]