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Biological processes in intertidal species follow tidal rhythms that enhance survival and fitness. Whereas tidal effects on behaviour and metabolic rates have been widely studied, impacts on other key process such as protein synthesis are still poorly understood. To date, no studies have examined the effect of immersion/emersion and tidal cycles on protein synthesis rates (ks). Patella vulgata is an intertidal limpet present in North-Eastern Atlantic rocky shores from high to low shore. Previously reported P. vulgata respiration and heart rate measurements suggest aerobic metabolism is maintained during emersion and growth rates increase from high to low shore, but whether these patterns are reflected in ks is currently unclear. Here, we measured for the first time in any intertidal organism, ks, RNA to protein ratios and RNA translational efficiency (kRNA) in P. vulgata over a full tidal cycle, at three different shore heights. ks increased during emersion (p < 0.001) and was significantly higher in low shore animals compared to the other shore heights (p < 0.001), additionally ks was negatively correlated to body mass (p = 0.002). RNA to protein ratios remained unchanged over the tidal cycle (p = 0.659) and did not vary with shore height (p = 0.591). kRNA was significantly higher during emersion and was also higher in low shore limpets (p < 0.001). This study demonstrates that P. vulgata increases ks during emersion, an important adaptation in a species that spends a considerable amount of its lifecycle emersed. Intertidal species are highly exposed to increasing air temperatures, making knowledge of physiological responses during emersion critical in understanding and forecasting climate warming impacts. [ABSTRACT FROM AUTHOR]

Management policies are crucial for safeguarding sustained and stable marine biodiversity amidst ongoing pressures such as land use change, pollution, resource overexploitation, invasive alien species and climate change. China established a nature's contributions to people value realization policy (NCPVR) in 2021, aiming to encourage stakeholders to prioritize environmentally beneficial production and consumption choices, thereby stimulating intrinsic public motivation for ecological conservation. Biodiversity conservation is an integral component of the NCPVR policy. A choice experiment method was employed to investigate the changes in public preferences for marine biodiversity conservation in Jiaozhou Bay before and after the enactment of the NCPVR policy (in 2017 and 2023, respectively), aiming to evaluate the effectiveness of the policy on marine biodiversity conservation. The results indicate that two years after the implementation of the NCPVR, the public's overall breadth and depth of awareness regarding marine biodiversity increased. Additionally, public preferences for marine biodiversity conservation increased, expanding from two categories in 2017 (shallow-water swimming organisms and marine plants) to five categories in 2023 (with the addition of seabirds, plankton, and intertidal and benthic organisms). The willingness to pay (WTP) for seabirds, plankton, and intertidal and benthic organisms, as well as shallow-water swimming organisms, increased from 32.21~85.77 CNY/person·year to 98.21~140.49 CNY/person·year. China's NCPVR policy effectively conveyed important information about biodiversity conservation in the short term, enhancing public awareness and preferences for marine biodiversity conservation. The study also revealed that economic incentive policies for NCPVR remain at the conceptual propaganda level and lack operational incentives for biodiversity conservation. It is recommended that the government deepen the design of value realization pathways and market trading arrangements to stimulate the intrinsic motivation of the public for marine biodiversity conservation and ensure the long-term effectiveness of policies. [ABSTRACT FROM AUTHOR]

The article "Unveiling the enigmatic cone snails along the coastal environments of the South Andaman Islands: diversity, distribution and their habitat preference" published in Frontiers in Marine Science explores the diversity, distribution, and habitat preferences of cone snails in the South Andaman Islands. The study reveals that Conus ebraeus is the predominant species among the nine study sites, with Conus litteratus and Conus leopardus found exclusively in specific locations with soft, muddy substrates. The research highlights the importance of substrate type, waterline zones, and habitat characteristics in shaping the distribution patterns of cone snails, emphasizing the need for responsible management and conservation practices. [Extracted from the article]

Disentangling the effects of cyclical variability in environmental forcing and long‐term climate change on natural communities is a major challenge for ecologists, managers, and policy makers across ecosystems. Here we examined whether the vertical distribution of rocky intertidal taxa has shifted with sea‐level variability occurring at multiple temporal scales and/or long‐term anthropogenic sea‐level rise (SLR). Because of the distinct zonation characteristic of intertidal communities, any shift in tidal dynamics or average sea level is expected to have large impacts on community structure and function. We found that across the Northeast Pacific Coast (NPC), sea level exhibits cyclical seasonal variability, tidal amplitude exhibits ecologically significant variability coherent with the 18.6‐year periodicity of lunar declination, and long‐term sea‐level rise is occurring. Intertidal taxa largely do not exhibit significant vertical distribution shifts coherent with short‐term (monthly to annual) sea‐level variability but do exhibit taxa‐specific vertical distribution shifts coherent with cyclical changes in lunar declination and long‐term SLR at decadal timescales. Finally, our results show that responses to cyclical celestial mechanics and SLR vary among taxa, primarily according to their vertical distribution. Long‐term SLR is occurring on ecologically relevant scales, but the confounding effects of cyclical celestial mechanics make interpreting shifts in zonation or community structure challenging. Such cyclical dynamics alternatingly amplify and dampen long‐term SLR impacts and may modify the impacts of other global change related stressors, such as extreme heat waves and swell events, on intertidal organisms living at the edge of their physiological tolerances. As a result, intertidal communities will likely experience cyclical periods of environmental stress and concomitant nonlinear shifts in structure and function as long‐term climate change continues. Our results demonstrate that consistent, large‐scale monitoring of marine ecosystems is critical for understanding natural variability in communities and documenting long‐term change. [ABSTRACT FROM AUTHOR]

Introduction: Coastal marine ecosystems, are particularly susceptible to climate change. One such threat is atmospheric heatwaves, which are predicted to increase in frequency, duration, and intensity. Many intertidal organisms already live at the edge of their thermal tolerance limits and heatwaves can outstretch an organism's ability to compensate in the short term. In June 2021 the Pacific Northwest region of North America, including the Salish Sea, experienced a significant atmospheric heatwave during some of the lowest tides of the year. This was followed by numerous reports of dead and dying intertidal marine organisms region-wide. A semi-quantitative rapid assessment found a range of both species- and location-specific effects but generally recorded widespread negative impacts to intertidal shellfish species across the Salish Sea. Methods: Following these results, we opportunistically analyzed data collected by intertidal bivalve resource managers from the region. These datasets allowed us to examine regional density and size data for clam and oyster populations before and after the heatwave to increase our quantitative understanding of heatwave effects. Results: We found a range of responses including positive and negative effects of the heatwave on clam and oyster density. While we generally found small changes in bivalve size, some site-species combinations displayed large shifts in size frequency. Many of our analyses did not indicate even moderate statistical support, even with large changes in the mean, driven in part by high variability in the data. Time intervals between surveys, ranging from 2 to over 25 months, had little effect on observed variability indicating that any heatwave-induced effects may be masked by variability inherent to the population ecology and/or survey methodology. Discussion: This analysis has highlighted the need for intertidal resource managers, and the greater research community, to consider alternative survey approaches designed to constrain variability in order to detect the effects of acute or extreme events. With the effects of climate change predicted to become more intense, targeted survey approaches may be needed to detect the effects and implications of such events and to continue effective management of intertidal bivalves in the Salish Sea and worldwide. [ABSTRACT FROM AUTHOR]

The boundary between land and sea is among the most extensive and extreme ecological barriers on planet Earth. Intertidal organisms living at this junction are subject to potentially lethal conditions related to desiccation, temperature fluctuations, and wave shock. Although difficult to quantify at a global level, rocky coasts account for between a third and three-quarters of all shorelines today. Resistant to coastal erosion, rocky coasts also exhibit adaptations by marine invertebrates and marine algae within intertidal zones that are geographically widespread. Biotic composition is variable depending on the tidal range at any given place and on climatic differences between tropical and more temperate latitudes. Contemporary granite shores having low recession rates with well-established biotic zones are reviewed in three regions: Mount Desert Island in Maine, USA (44° N latitude), Mahé and Praslin islands in Seychelles (4°30′ S Latitude), and Lizard Island off the coast of Queensland, Australia (14°40′ S Latitude). The zonal composition and overall biotic diversity at these locations are compared, as well as the fossilization potential of key biota. Over the Phanerozoic time period during the last 538 million years, the ratio between land and ocean varied as a function of plate tectonics depending on the maximum dispersal or coalescence of continents and on relative changes in global sea level. Fossil biotas from a dozen paleoislands with dominant rocky shores that range from 485 million to 125,000 years in age are reviewed to show diversification through time, taking into account episodic mass extinctions. Relationships between storm tracks and volcanic eruptions that factor into physical disruptions are also considered as means of rapid burial and preservation. Themes related to rocky-shore ecology and paleoecology benefit from the cross-fertilization of ideas by marine biologists and marine paleontologists. It is hoped this review may attract a cohort of new students to these allied fields of study, especially in Asia, Africa, and South America. [ABSTRACT FROM AUTHOR]

The recruitment of intertidal benthic organisms that have planktonic larvae is influenced by hydrodynamics at multiple nested spatial scales, ranging from tens of centimetres to kilometres. Intertidal mussel populations on the south coast of South Africa are known to exhibit higher cover within bays than on open-coast shorelines. This study tested the hypothesis that topographically driven differences in hydrodynamics will result in comparatively higher recruitment within bays. Specifically, we estimated recruitment rates of the native brown mussel Perna perna and the invasive Mediterranean mussel Mytilus galloprovincialis (family Mytilidae) over five spring tidal cycles at bay and open-coast sites at both Algoa Bay and St Francis Bay, and the data were then correlated with upwelling indices derived from wind data. We recorded 3 313 P. perna and 2 485 M. galloprovincialis recruits individually and found that mussel recruitment within bays was as much as two orders of magnitude higher than on open coast. The relationship between recruit numbers and upwelling indices was positive, although non-significant, and markedly stronger for the open-coast sites (where r2 values were 0.51–0.59). These results indicate that better mussel cover within bays can be at least partially explained by higher recruitment rates. [ABSTRACT FROM AUTHOR]

Wave climate is shifting over the last decades along the Atlantic coasts of Europe ultimately driven by large-scale patterns of atmospheric variability forced by anthropogenic global warming. Changes in wave height and surf zone orbital currents are hypothesized to drive marked shifts in the shape of intertidal organisms such as the stalked barnacle Pollicipes pollicipes, whose quality and market price are known to decrease non linearly with the peduncle length: width ratio S. This study evaluates wave trends in NW Iberian Peninsula, using the Spanish Port System 2006–2020 SIMAR wave hindcast. On the other hand, trends in stalked barnacle morphology and quality are estimated from 26 sites at the management regions of Baiona and A Guarda between 2011 and 2020. Results show evidence of temporal changes in barnacle quality and, especially, morphometry caused by simultaneous shifts in winter wave induced orbital currents. Because of the non linear relationship between S and the high quality threshold, large increases in S are usually translated to small reductions in quality. However, we identified a tipping point around S = 2.4 that if surpassed can lead to great drops in barnacle quality. In addition, changes in wave forcing will have different effects at each extraction site, as trends in wave climate are decoupled from barnacle morphometry at steeper sites sheltered from the predominant wave direction. In conclusion, this knowledge could be applied to develop site specific barnacle harvesting strategies based on annual wave climate forecasts. [ABSTRACT FROM AUTHOR]

Large‐scale disturbance events provide ideal opportunities to directly study recolonisation processes in natural environments, via the removal of competitors and the formation of newly vacant habitat. A high magnitude earthquake in central New Zealand in 2016 created major ecological disturbance, with coastal tectonic uplift of up to ~ 6 m extirpating vast swathes of intertidal organisms. One of the affected species was Durvillaea antarctica (rimurapa or southern bull kelp), which is an important habitat‐forming intertidal macroalga capable of long‐distance dispersal. Across the complex fault system with varying amounts of uplift, the species was either locally extirpated or heavily reduced in abundance. We hypothesised that neutral priority effects and chance dispersal from other populations would influence which lineages would establish. We sampled individuals of D. antarctica across the uplift zone immediately after the earthquake in 2016 and then repeatedly sampled new recruits in the same areas between 2017 and 2020, using genotyping‐by‐sequencing to provide 'before' and 'after' genomic comparisons. Our results revealed strong geographic clustering but little evidence of new lineages establishing at disturbed sites, although populations at uplifted sites remain at remarkably low densities. We infer that recolonisation has thus far primarily originated from refugial, remnant patches within the uplift zone. To complement the phylogeographic analysis, we estimated oceanographic connectivity among the uplift zone sample locations. The connectivity modelling estimated that northbound dispersal of D. antarctica was more likely, but we have not yet detected southern genotypes in the recolonised populations. As the ongoing recolonisation process transitions from an ecological to an evolutionary timescale, change remains possible. This study provides the first genomic 'snapshots' of a natural recolonisation process following a large‐scale ecological disturbance event, and ongoing research has the potential to reveal important insight into both micro‐ and macroevolutionary processes. [ABSTRACT FROM AUTHOR]

There has been a limited number of studies on the effects of harmful algal blooms (HABs) on natural rocky intertidal ecosystems. From mid-September to early November 2021, an unprecedented HAB caused by Karenia selliformis hit the Pacific coast of southeast Hokkaido, Japan, for the first time, causing massive mortalities among marine organisms. To clarify the immediate impacts of the HAB on the abundance of 10 rocky intertidal species in four functional groups (macroalgae, sessile invertebrates, molluscan grazers, and molluscan carnivores), we focused on two questions: (1) How did the HAB affect the abundance of each species differently at the regional scale? and (2) How did the impacts of the HAB on the abundance of each functional groups vary spatially, and was the spatial variation of the HAB impacts related to the spatial distribution of the cell density of HAB species? To study these issues, we compared census data for 17 years before the HAB and within one month after it for five shores on the southeast coast of Hokkaido. The results showed that two macroalgae species and all three molluscan grazer species declined significantly after the HAB. Moreover, the decrease in molluscan grazers was significantly correlated with cell density. These results suggest that the impacts of the HAB in southeast Hokkaido on the abundance of rocky intertidal organisms are highly variable depending on species and locality, presumably because of differences in species-specific tolerances to HAB toxins and the spatial variation in the density of the HAB organisms. [ABSTRACT FROM AUTHOR]

The radioactive concentrations of 40K, 232Th and 226Ra in 11 intertidal sediment cores in the Red River Delta were determined, and radiological hazard indices for environmental risk were assessed. The values of 40K, 232Th and 226Ra activity were 656 Bq/kg, 49.8 Bq/kg and 37.0 Bq/kg, respectively. The values of radiological hazard indices such as radium equivalent activity (Raeq), absorbed dose rate (ADR), equivalent annual effective dose (AEDE), representative gamma index (Iγr), index active use, external hazard index (Hex), annual gonadal equivalent dose (AGDE) were 158.7 Bq/kg, 74.5 nGy/h, 0.09 mSv/year, 1.18, 1.0, 0.40, and 496.4 µSv/year, respectively. The results obtained of this study showed that eleven sediment cores can be divided into two groups, of which the radioactive concentrations of 40K, 232Th and 226Ra in group 2 were higher than in group 1, and the concentration of radionuclides in sediments was higher than the global average, except for 226Ra in group 1. The ADR, AEDE, Iγr and AGDE indices were above UNSCEAR's recommended levels for both groups. The results of this study show that sediments have the potential to impact organisms in the intertidal zone and are safe for use as construction materials. [ABSTRACT FROM AUTHOR]

Symsagittifera roscoffensis forms a photosymbiotic relationship with the alga Tetraselmis convolutae within the intertidal zone. Juveniles lack algal symbionts at birth and acquire them from the environment. Requiring light for photosynthesis, they position themselves within the water column while also balancing the risk of being washed away. To understand their behavioural adaptations, we conducted experiments on their movement in response to algal cues (chemotaxis), light gradients (phototaxis), and mechanical vibrations. Aposymbiotic juveniles showed three times more positive displacement towards algae. Adults exhibited positive phototaxis but retreated from high light intensity. When introduced to a column with a light source, the worms remained just below the surface. In the mechanical vibration experiment, worms only descended when vibrations exceeded a threshold. These findings suggest that S. roscoffensis has chemotactic abilities crucial for acquiring algae and acquires light for photosynthesis while minimizing dispersal risk and photoinhibition, facilitating its life cycle in the intertidal zone. [ABSTRACT FROM AUTHOR]

Mucus-mediated communication plays a significant role in shaping community dynamics, particularly in marine organisms found in intertidal zones with complex topography. In this study, we investigated the host preference of a flatworm Stylochoplana pusilla, which lives symbiotically with intertidal gastropods, and its responses to the host and conspecific mucus. Our line transect surveys revealed differences in flatworm prevalence among sympatric gastropods, with multiple flatworms found in a single host individual, indicating host preference. The body mucus of gastropods and flatworms was applied to one side of a Petri dish to experimentally determine whether flatworms prefer the mucus-coated side under light and dark conditions. However, contrary to our expectations, the experiments in both light and dark conditions showed that the mucus of none of the host gastropods effectively attracted flatworms, suggesting that mucus-mediated communication may not be the primary factor in establishing host preference, and other ecological factors may play a role. Nonetheless, under dark conditions, flatworms were attracted to conspecific mucus, indicating that they may engage in collective homing behaviour or conspecific aggregation to find a suitable position in the mantle cavity. Overall, our results highlight the complex ecological interactions involved in shaping symbiosis between flatworms and gastropods. [ABSTRACT FROM AUTHOR]

Barnacles are crustaceans that are critical model organisms in intertidal ecology and biofouling research. In this study, we present the first mitochondrial genome of Striatobalanus tenuis which is a circular molecule of 15,067 bp in length. Consistent with most barnacles, the mitochondrial genome of S. tenuis encodes 37 genes, including 13 PCGs, 22 tRNAs and 2 rRNAs. A novel insight into the phylogenetic analysis based on the nucleotide data of 13 PCGs showed that the S. tenuis clusters with Striatobalanus amaryllis (bootstrap value = 100) of the same genus, then groups with other Balanoidea species, the Chelonibiidae, Austrobalanidae and Tetraclitidae cluster together forming superfamily Coronuloidea. The result can help us to understand the novel classification within Balanomorpha. [ABSTRACT FROM AUTHOR]

Most studies on island biogeography have focused on the terrestrial taxa; however, there are few studies on the drivers of diversity and community structure of intertidal organisms on islands. We evaluated the effect of landscape and marine environmental factors on the species richness (SR), functional diversity (FD), and community structure (SES.MFD) of intertidal invertebrates among the overall, inhabited, and uninhabited islands. Using the data on the intertidal organisms from 78 islands in South Korea, we implemented variable selection and piecewise structural equation modeling to determine the causal relationships between the SR, FD, and SES.MFD with four landscapes (i.e., island area, coastline length, distance from the mainland, and structural connectivity) and three marine environment factors (i.e., mean annual sea surface temperature variation, wind speed, and evapotranspiration). The coastline length had a positive effect on the SR and SES.MFD in the overall islands including inhabited and uninhabited islands. The SR and FD were negatively affected by the variation in sea surface temperature. The relative importance of the landscape and marine environmental factors differed between the inhabited and uninhabited islands. That is, the inhabited islands were mainly affected by the coastline length, whereas uninhabited islands were regulated by marine environmental factors. Our results demonstrated that the biotic factors of the island intertidal ecosystems are controlled by the interactions between the biotic and various environmental factors. Moreover, the results emphasize that the water stress on the intertidal organisms due to climate change may lead to a loss of biodiversity and functional clustering. [ABSTRACT FROM AUTHOR]

Echinometra lucunter is a common Caribbean sea urchin, which the abundance and distribution were evaluated along a rocky platform at Cepe beach, Venezuela. Two surveys were conducted along transects perpendicular and parallel to the coast, from the shore to the wave breaking zone (WB), using 1m2 quadrat method. In survey-1 the smaller sea urchins (<1.8 cm) occurred in the tide pool zone (TP) and medium and large dominated in the WB. The average density recorded in the WB and TP (140.2 and 272.7 ind/m2 respectively) are among the highest values reported in the Caribbean. The maximum density recorded was 562 ind/m2 in the TP and most of them were juveniles (<1.8 cm). In survey-2 sea urchins (³3.0 cm) density ranged from 1 to 156 ind/m2 and the overall average was 29.6 (± 32.4) ind/m2. The highest density occurred in the platform western sector (average 43.2 ±41.3 ind/m2). In the transects parallel to the coast the sea urchin's abundance gradually decreased from the WB (130 ±12 ind/m2) towards the coast (0.3 ±0.37 ind/m2). In conclusion, the E. lucunter densities recorded on the Cepe beach platform are the highest values reported in the Caribbean. [ABSTRACT FROM AUTHOR]

Shore height is one of the physical factors in marine ecology affecting marine organisms in the upper intertidal area. This study aimed to investigate the effect of shore height on the distribution of three dominant seagrass species in the upper intertidal area of the Andaman Sea in the provinces of Krabi and Trang, southern Thailand. Shore height data were collected from 155 stations in 2021 and 273 stations in 2022, using a theodolite (AP-8 Nikon) and a surveyors' rod. The measured height from the field was calculated relative to the height of water predicted above the lowest low water on a specific date and time, thus shore height is presented as the height above lowest low water (cm H_LLW). The total aboveground biomass of the three dominant seagrass species, namely, Enhalus acoroides, Thalassia hemprichii and Halophila ovalis, was observed through a modified Rapid Visual Estimation Technique. At different shore heights (0-100, 100-180, and above 180 cm H_LLW), the coverage of total seagrasses was highly significant (F = 9.08, p = 0.002); the biomass was also highly significant (F = 18.72, p<0.001). The highest total biomass (10.56±6.66 g dw·m-2 with 55.00±24.05% coverage) was found at 100-120 cm H_LLW. The shore height affected the presence of seagrass, with distinct shallow thresholds observed for E. acoroides, T. hemprichii and H. ovalis of 200, 200 and 220 cm H_LLW, respectively. The findings from this study hold significant implications for guiding decisionmaking processes related to seagrass restoration and transplantation efforts. [ABSTRACT FROM AUTHOR]

This article examines the intertidal ecological research of the commercial lab owner and popular science writer Edward F. Ricketts, best known as the prototype for John Steinbeck’s character “Doc” in the novel Cannery Row (1945). Ricketts’s friendship with Steinbeck and unconventional philosophical style have regrettably overshadowed his scientific work, particularly his novel faunal zonation surveys of the North American Pacific littoral in the 1930s and 1940s. These surveys resulted in a landmark handbook, Between Pacific Tides (1939), designed for novices and specialists alike. Ricketts’s work demonstrates how the place of ecological investigation (Billick and Price)—here Monterey Bay’s pounding surf, storm-tossed debris, eclectic bohemianism, and the collaborative energies at Hopkins Marine Station— “imprinted” West Coast animal ecology. At first, Ricketts adopted the physiological methods and conceptions of ecological holism he had learned at the University of Chicago under mentor Warder C. Allee in the early 1920s. Allee had conducted his investigations of intertidal organisms in the relatively placid bays and estuaries at the Woods Hole research center on Cape Cod, Massachusetts. Allee envisioned animal aggregations as higher-order societies guided by “unconscious cooperation” and evolving toward a climax state. Yet Ricketts found that physiochemical factors, such as temperature and salinity, could not explain the distribution of organisms amid the Pacific’s far more precarious rough-and-tumble surf, nor could they account for fierce competition among organisms. Rejecting Allee’s cooperative metaphors, Ricketts came to see community structure as an unintended result of tidepool invertebrates’ Darwinian struggle to occupy resource niches—a “set of sieves” that transferred nourishment from one part of the aggregation to the next, binding it together in interlocking food webs. Through dialogue with Steinbeck about the implications of modern physics during their Sea of Cortez voyage (1940), Ricketts developed a “unified field hypothesis” to conceptualize the dynamic interwovenness created by transfers of metabolic energy. Yet Steinbeck ultimately held fast to a superorganismic understanding of ecological holism—a hierarchical relationship between constituents and the whole that underlays the novelist’s idea of the human “phalanx” in Grapes of Wrath and other works. The article offers new insights about the ecological origins of Steinbeck and Ricketts’s disputes over “non-teleological” reasoning and the pair’s divergent understandings of nature, society, and progressive politics. [ABSTRACT FROM AUTHOR]

Plastic pollution has become a significant environmental concern, with profound consequences for ecosystems worldwide, particularly for marine systems. Our study introduces 'plastiskin', a newly identified plastic pollution type encrusting intertidal organisms. Found on mussels and macroalgae, 'plastiskin' was composed of polypropylene and polyethylene. In mussels, the presence of 'plastiskin' was correlated with the absence of living endoliths in areas of the shells it covered, indicating a detrimental impact on the symbiotic endolithic community residing within mussel shells. In addition, we examined the potential negative effects of 'plastiskin' on the photosynthetic efficiency of macroalgae, however, these findings were inconclusive, stressing the need for further studies with larger sample sizes. Our baseline observations may serve as a groundwork for further investigation into the spatial distribution, temporal persistence, and ecological ramifications of 'plastiskin'. potential incorporation of 'plastiskin' as a new marine debris category into management and monitoring frameworks warrants serious consideration. • Our study introduces plastiskin, a new type of plastic pollution on intertidal organisms. • We identified it as polypropylene and polyethylene adhering to macroalgae and mussels. • We linked it to absence of microbial endoliths, mussels' symbiotic communities. • Potential incorporation of plastiskin into marine debris categories warrants consideration. [ABSTRACT FROM AUTHOR]

Sessile intertidal organisms live in a harsh environment with challenging environmental conditions and increasing anthropogenic pressure such as microplastic (MP) pollution. This study focused on effects of environmentally relevant MP concentrations on the metabolism of intertidal Pacific oyster Crassostrea gigas , and its potential MP-induced vulnerability to warming during midday low tide. Oysters experienced a simulated semidiurnal tidal cycle based on their natural habitat, and were exposed to a mixture of polystyrene microbeads (4, 7.5 and 10 µm) at two environmentally relevant concentrations (0.025 µg L−1 and 25 µg L−1) for 16 days, with tissue samplings after 3 and 12 days to address dose-dependent effects over time. On the last day of exposure, the remaining oysters were additionally exposed to low tide warming (3 °C h−1) to investigate possible MP-induced susceptibility to aerial warming. Metabolites of digestive gland and gill tissues were analysed by using untargeted 1H nuclear magnetic resonance (NMR) based metabolomics. For the digestive gland metabolite profiles were comparable to each other independent of MP concentration, exposure time, or warming. In contrast, gill metabolites were significantly affected by high MP exposure and warming irrespective of MP, initiating the same cellular stress response to counteract induced oxidative stress. The activated cascade of antioxidant defence mechanisms required energy on top of the general energy turnover to keep up homeostasis, which in turn may lead to subtle, and likely sub-lethal, effects within intertidal oyster populations. Present results underline the importance of examining the effects of environmentally relevant MP concentrations not only alone but in combination with other environmental stressors. • Assessment of relevant microplastic (MP) concentration effects on intertidal oyster. • Investigation of MP-induced vulnerability of intertidal oysters to low tide warming. • Digestive gland metabolites were unaffected from both MP exposure and warming. • Only high MP exposure induced a cellular stress response at ambient temperature. • All treatments expressed a cellular stress response to warming during emersion. [ABSTRACT FROM AUTHOR]

The rocky intertidal is an iconic seascape of the California coast. Existing at the land-sea interface, the rocky intertidal is one of the most accessible and diverse habitats making it an extremely important resource for education, recreation, and harvest. They are particularly important to the coastal Indigenous Nations of California who have a deep cultural connection and inherent stewardship rights to their coast. Indigenous Nations have studied and observed the intertidal since time immemorial, passing on and adding to this wealth of traditional knowledge through the generations. They know the current state and the history of their specific intertidal systems better than anyone. As such, we are working in partnership with the Tolowa Dee-ni’ Nation on one of three study areas in this pilot project to combine expertise and implement a novel approach to the study of climate change impacts on the California rocky intertidal. As a highly productive ecosystem defined by strict ecological zonation due to biological and physical tolerances, the rocky intertidal is presumed to be particularly susceptible to global environmental change, especially sea level rise (SLR). However, it has long been assumed that the biological response of intertidal organisms to climate change will occur slowly over long periods of time that more or less mirror the long term trend of SLR. This study offers preliminary evidence that this may not be the case. In this collaborative study we use large-area imaging to create 3-dimensional (3D) habitat maps and digital elevation models of the rocky intertidal at three sites: Pyramid Point State Marine Conservation Area (PPSMCA); Cabrillo National Monument (CNM); and Scripps Coastal Reserve (SCR), which bookend the southernmost and northernmost tidal regimes of the state. The Tribal Intertidal Digital Ecological Survey (TIDES) project is a product of collaboration between Scripps Institution of Oceanography faculty and students and the Natural Resources Department of the Tolowa Dee-ni’ Nation. Over time, this partnership will build overall capacity for adaptive coastal management by combining traditional knowledge of historically observed patterns in intertidal communities with advanced imaging/mapping techniques that maximize data acquisition in the field. This project and the foundational partnership and guidance of the Tolowa Dee-ni’ Nation establishes the framework for diverse coastal communities and managers to implement high-resolution large-area imaging of rocky intertidal habitats. This collaborative approach can better inform future changes associated with SLR while creating a digital archive to address a wide range of future research questions as they arise, including areas of interest such as population dynamics of culturally important species.

Salinity is a key factor affecting biological processes and biodiversity in estuarine systems. This study investigates temporal and spatial changes in salinity at a basin-wide scale for 2005–2015 in the Dutch Wadden Sea. Scan statistics is applied to track salinity variations systematically and to detect potential clusters, i.e., estuarine regions marked by anomalous high-salinity (or low-salinity) values in a certain period (i.e., strong deviations from the expected value in a statistical sense). Clusters' statistical significance has been assessed via Monte Carlo simulations. Particular attention is devoted to event-driven spatial and temporal patterns characterized by extreme salinity values since these episodes dramatically increase stress levels on organisms living in intertidal areas. Periodic components in the modeled salinity time series are identified using wavelet analysis and eventually removed from the signal before performing scan statistics. Wavelet analysis suggests that tides are the chief agent controlling salinity fluctuations in the system at within-day time scales, whereas no dominant periodicities were detected at longer time scales. Scan statistics reveal long-lasting clusters next to the main freshwater outlets and within the areas characterized by low water exchanges. In contrast, active regions of the estuary can efficiently counteract extreme events and quickly recover their pre-perturbation conditions. Finally, by analyzing the freshwater dispersal in the system, it is found that clusters' occurrence is related to episodic events characterized by extreme conditions in the southwesterly wind and freshwater discharge. This research demonstrates that scan statistics can be used as a powerful tool for spatiotemporal analyses of marine systems and for identifying data-clustering that may be indicative of emerging environmental hazards (e.g., due to climate change). [ABSTRACT FROM AUTHOR]

Intertidal organisms must tolerate daily fluctuations in environmental parameters, and repeated exposure to co-occurring conditions may result in tolerance to multiple stressors correlating. The intertidal copepod Tigriopus californicus experiences diurnal variation in dissolved oxygen levels and pH as the opposing processes of photosynthesis and cellular respiration lead to coordinated highs during the day and lows at night. While environmental parameters with overlapping spatial gradients frequently result in correlated traits, less attention has been given to exploring temporally correlated stressors. We investigated whether hypoxia tolerance correlates with low pH tolerance by separately testing the hypoxia and low pH stress tolerance separately of 6 genetically differentiated populations of T. californicus. We independently checked for similarities in tolerance for each of the two stressors by latitude, sex, size, and time since collection as predictors. We found that although hypoxia tolerance correlated with latitude, low pH tolerance did not, and no predictor was significant for both stressors. We concluded that temporally coordinated exposure to low pH and low oxygen did not result in populations developing equivalent tolerance for both. Although climate change alters several environmental variables simultaneously, organisms' abilities to tolerate these changes may not be similarly coupled. [ABSTRACT FROM AUTHOR]

Animal biodiversity is greatly underestimated in nontemperate marine regions, especially for intertidal benthic organisms such as oysters. Recent surveys in the northern Arabian Gulf suggest the presence of numerous unidentified species, some of which form shallow reef ecosystems while others are cryptic and found under rocks. In this study, we focused on small oysters from Kuwait, which show typical characteristics in common with the genus Ostrea except for the presence of lophine chomata that would link it to the genera Lopha, Dendostrea, and Alectryonella. Phylogenetic analyses based on mitochondrial and nuclear markers unambiguously placed the Kuwait oyster within the Ostreinae as a sister to the Japanese species Ostrea futamiensis. The hypothesis that the Kuwait oyster represents a new species was assessed with phylogenetic and species delimitation methods combined with a morphological assessment. Results corroborated the Kuwait oysters as a new species herein described as Ostrea oleomargarita Oliver, Salvi, and Al-Kandari, sp. nov. The phylogeny of the Ostreinae shows extensive disagreement between morphology-based genera and phylogenetic clades. The genus Ostrea is polyphyletic, and the form and distribution of taxonomic characters such as chomata are not as definitive as suggested in previous studies. This study, along with other recent investigations, confirmed the Arabian Gulf as a key region for discovering marine animal diversity and suggested a possible biogeographic divide between the Eastern and Western Indo-Pacific. A pattern that has been documented in a growing number of taxa and that warrants further research attention. [ABSTRACT FROM AUTHOR]

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The intertidal organism Tegillarca granosa can survive under frequent hypoxia/reoxygenation (H/R) exposure. Sulfides as accompanying products in benthic hypoxic environments, may play an important regulatory role, but the mechanisms are not well understood. This article investigated the physiological and molecular changes of T. granosa after adding different concentrations of sulfides (0.1, 0.5, 1 mM) at 72 h into a 120-h exposure to hypoxia, as well as the recovery state of 24 h of reoxygenation. The results indicated that H/R stress induces ROS production and mild mitochondrial depolarization in clams, and sulfide can participate in its regulation. Among them, a low concentration of sulfide up-regulated glutathione content and alternative oxidase activity, maintained the stability of antioxidant enzymes, and up-regulated the expression of the survival genes XIAP / BCL-xl which mediate cell survival via the NFκB signaling pathway. High concentrations of sulfide had a significant inhibitory effect on the p38/MPAK pathway and inhibited intrinsic apoptosis caused by ROS accumulation during reoxygenation. Taken together, our study suggested that different concentrations of sulfides are involved in regulating the endogenous apoptosis of clams during H/R. • Hypoxia/reoxygenation stress leads to ROS accumulation and induces caspase dependent intrinsic apoptosis. • Low concentration sulfide treatment plays a major regulatory role in the hypoxic stage. • High concentration sulfide inhibits the p38/JNK MAPK pathway in hypoxia period. • High concentration sulfide attenuates oxidative stress through TRAF2-NFκb pathway in the reoxygenation period. [ABSTRACT FROM AUTHOR]

For sessile intertidal organisms, periods of low tide impose both cellular and physiological challenges that can determine bathymetric distribution. To understand how intertidal location influences the cellular response of the bivalve Perumytilus purpuratus during the tidal cycle (immersion-emersion-immersion), specimens from the upper intertidal (UI) and lower intertidal (LI) of bathymetric distribution were sampled every 2 h over a 10-h period during a summer tidal cycle. Parallelly, organisms from the UI and LI were reciprocally transplanted and sampled throughout the same tidal cycle. Levels of oxidative damage (lipid peroxidation and protein carbonyls) as well as total antioxidant capacity and total carotenoids were evaluated as cellular responses to variations in environmental conditions throughout the tidal cycle. The results indicate that both the location in the intertidal zone (UI/LI), the level of aerial exposure, and the interaction of both factors are determinants of oxidative levels and total antioxidant capacity of P. purpuratus. Although oxidative damage levels are triggered during the low tide period (aerial exposure), it is the UI specimens that induce higher levels of lipid peroxidation compared to those from the LI, which is consistent with the elevated levels of total antioxidant capacity. On the other hand, organisms from the LI transplanted to the UI increase the levels of lipid peroxidation but not the levels of protein carbonyls, a situation that is also reflected in higher levels of antioxidant response and total carotenoids than those from the UI transplanted to the LI. The bathymetric distribution of P. purpuratus in the intertidal zone implies differentiated responses between organisms of the lower and upper limits, influenced by their life history. A high phenotypic plasticity allows this mussel to adjust its metabolism to respond to abrupt changes in the surrounding environmental conditions. • Bathymetric location and time of aerial exposure influences REDOX metabolism. • Higher oxidative damage is generated in mussels from the upper intertidal limit. • Transplanted mussels from low to up fringe showed higher oxidative damage. • During emersion carotenoids increased in transplanted mussels from the lower fringe. [ABSTRACT FROM AUTHOR]

Understanding the life‐stage specific vulnerability of ectotherms to temperature increases is crucial to accurately predicting the consequences of current and future global climate change. Here, we examined ontogeny‐specific thermal vulnerability of three intertidal, bimodal (i.e., air and water) breathing crabs from tropical and warm temperate latitudes to address this issue. Spawning females and embryos of intertidal crabs from warm temperate latitudes were more vulnerable to temperature increases than tropical conspecifics, particularly in water. Our findings do not fully support the Climate Variability Hypothesis for setting upper thermal limits, but correspond with the Oxygen‐ and Capacity‐Limited Thermal Tolerance hypothesis, suggesting ontogeny‐specific aerobic capacity dictates overall species' thermal sensitivity. Bimodal breathing efficiency as an evolutionary adaptation, ontogenetic stage and local climate adaptation are therefore significant factors to consider when evaluating the vulnerability of intertidal ectotherms to temperature increases and the consequences of climate changes for intertidal organisms, populations and communities. [ABSTRACT FROM AUTHOR]

Marine intertidal organisms face extreme environmental fluctuations due to tidal cycles. To investigate the impact of environmental changes (high salinity, sea surface temperature, and anthropogenic pollution) on the health of the coastal area, we selected the dominant intertidal organisms: sponge (Cinachyrella cf. cavernosa) and zoanthid (Zoanthus sansibaricus) as our model system from a rocky beach Anjuna, Goa, India. Sponges and zoanthids were transplanted from their natural habitat (mid-tide pools) to new habitat (upper-tide pools). The study was carried out for 15 days when these pools experienced flushing during the first and last 5 days (high tide was >1.8 m) and no flushing during the middle 5 days (high tide was <1.8 m). The indices of physiological response (such as in budding activity and oscular openings) in the sponge and (chlorophyll estimation and symbiotic zooxanthellae count) in zoanthid were estimated at natural and transplanted habitats. Upper intertidal pools experienced intense temperature (29.9–36.15°C), salinity (35.03–46.7 ppt) and variability in dissolved oxygen (3.2–9.5 mg/l). The transplanted sponge did show the closure of oscula (90.62%) and reduction in buds (40–94.9%), but they could survive beyond 15 days. While transplanted zoanthid showed bleaching and did not survive beyond 72 h due to reduced chlorophyll content (up to 44.21%) and zooxanthellae count (34.54%). Our results depicted the differential tolerance capacity of sessile organisms like sponge and zoanthid to environmental changes, which govern the vertical zonation in the rocky intertidal region. It highlights the role of these sessile invertebrates as early indicators of environmental changes. [ABSTRACT FROM AUTHOR]

Circadian clocks are an intrinsic element of life that orchestrate appropriately timed daily physiological and behavioural rhythms entrained to the solar cycle, thereby conferring increased fitness. However, it is thought that the first archaic 'proto-clocks' evolved in ancient cyanobacteria in a marine environment, where the dominant time cues (zeitgebers) probably would have been lunar-driven and included tidal cycles. To date, non-circadian 'marine clocks' have been described with circatidal (~12.4 h), circasemilunar (~14.8 days), and circalunar (~29.5 days) periodicity, mostly studied in accessible but temporally complex intertidal habitats. In contrast to the well-described circadian clock, their molecular machinery is poorly understood, and fundamental mechanisms remain unclear. We propose that a multi-species approach is the most apposite strategy to resolve the divergence that arose from non-circadian clockwork forged in an evolutionary environment with multiple zeitgebers. We review circatidal clock models with a focus on intertidal organisms, for which robust behavioural, physiological, or genetic underpinnings have been explicated, and discuss their relative experimental merits. Developing a comprehensive mechanistic understanding of circatidal clocks should be a priority because it will ultimately contribute to a more holistic understanding of the origins and evolution of chronobiology itself. [ABSTRACT FROM AUTHOR]

In coastal areas where vast intertidal flats have been lost due to development, organisms inhabiting intertidal flats try to expand the distribution to isolated habitats. The authors collected the threatened gastropod Batillaria multiformis (Lischke 1869) for the first time in 27 years on the intertidal flat of the Edogawa Drainage Canal, located in the innermost part of Tokyo Bay, where many large intertidal flats have been reclaimed. In recent years, this species' distribution has spread to the intertidal flats in the inner part of the bay, where this species once lived, but small individuals have not been found in those intertidal flats. We discuss potential policies for recovering B. multiformis in Tokyo Bay. [ABSTRACT FROM AUTHOR]

Global temperature increases are predicted to have pronounced negative effects on the metabolic performance of both terrestrial and aquatic organisms. These metabolic effects may be even more pronounced in intertidal organisms that are subject to multiple, abruptly changing abiotic stressors in the land-sea transition zone. Of the available studies targeting the intertidal environment, emphasis has largely been on water-breathing model organisms and this selective focus resulted in limited reliable forecasts on the impact of global warming on primarily air-breathing intertidal species. We investigated the thermal sensitivity of six phylogenetically related fiddler crab species that occupy different microhabitats on intertidal shores from south America and east Asia to test how bimodal-breathing intertidal ectotherms cope with thermal stress. We examined the metabolic physiology and thermal limits of the crabs by measuring their cardiac function and oxygen consumption along a thermal gradient. Their specific thermal microhabitat was also appraised. We found that subtropical fiddler crab species inhabiting vegetated microhabitats have lower upper lethal temperatures and therefore greater thermal sensitivity in comparison to their tropical counterparts. Additionally, females exhibited higher oxygen consumption and lower lethal temperatures in comparison to males. Our results contradict previous predictions that species from higher latitudes that experience greater temperature variability have broader latitudinal distributions, greater phenotypic plasticity and lower thermal sensitivity. Furthermore, the higher thermal sensitivity demonstrated by female fiddler crabs with respect to males strongly suggests a role of both gametogenesis and physiological dimorphism on the thermal performance of tropical and subtropical intertidal organisms. These observations ultimately, advocates for further studies on sex-biased and development-biased thermal sensitivity before drawing any generalizations based on a single sex or life stage.

Coastal habitats fluctuate with the 12.4 h tidal and 24 h light/dark cycle to predictably alter conditions such as air exposure, temperature, and food availability. Intertidal sessile bivalves exhibit behavioural and physiological adjustments to minimize the challenges of this environment. We investigated a high‐resolution time course of the changes in protein abundance in the gill tissue of the intertidal mussel Mytilus californianus in a simulated tidal environment of 12:12 h light:dark cycles and a matching 6:6 h high:low tide cycle within each 12 h period. Approximately 38% of detected proteins showed significant rhythms in their abundances, with diversity in the phases of rhythmic isoforms. The circadian rhythm was dominant in protein abundance changes, particularly with oxidative metabolism. A tidal cycle elicited changes within functional groups, including in cytoskeletal proteins, chaperones, and oxidative stress proteins. In addition to protein abundance changes, we found the possibility for post‐translational modifications driving rhythms, including methylation, mitochondrial peptide processing (proteolysis), and acylation. Dynamic changes in the proteome across functional categories demonstrate the importance of the tidal environment in entraining cellular processes, confirming that differential expression studies should not assume a static baseline of cellular conditions in intertidal organisms. [ABSTRACT FROM AUTHOR]

Intertidal zonation of organisms is well studied on rocky shores but less so in soft sediment communities. On rocky shores, communities are two dimensional, with biotic factors such as competition and predation setting the lower bound of a zone, whereas abiotic factors such as desiccation set the upper bound. In soft sediment communities, these patterns persist, but with a dynamic three‐dimensional ecosystem occupied by mobile infaunal organisms, zonation can be more difficult to quantify and detect. Hemichordate worms, however, deposit fecal casts at the surface, which can be easily identified and counted, making them a potential model system for identifying zonation in soft‐sediment systems. Here, we describe the intertidal zonation of hemichordate worms at two sites in Maine and Virginia. In Virginia, Saccoglossus kowalevskii occurs in the mid‐intertidal at densities up to 500 individuals per square meter, whereas a tube‐building polychaete, Spiochaetopterus oculatus, dominates the lower intertidal. In Maine, two hemichordate species, Saccoglossus bromophenolosus and Protoglossus graveolens, co‐occur at densities up to 100 individuals per square meter in the mid‐intertidal, whereas hermit crabs and errant polychaetes are numerically dominant in the low intertidal. Despite known chemical defenses, crustaceans readily consumed hemichordates in lab assays, although polychaetes did not. In a field tethering experiment, loss rates of hemichordate‐flavored agarose pellets increased as tidal height decreased, suggesting that the lower bound of the hemichordate zone could be set by biotic forces such as crustacean predation. Additionally, a field transplant experiment found low survivorship of hemichordates transplanted to the upper intertidal, suggesting that desiccation may set their upper bound. These results are broadly consistent with prior studies of zonation in soft sediments, and expand our limited understanding of basic hemichordate ecology. [ABSTRACT FROM AUTHOR]

Opportunistic and unstructured observations of biodiversity crowdsourced from volunteers, community, and citizen scientists make up an increasingly large proportion of our global biodiversity knowledge. This incredible wealth of information exists in real time at both high resolutions and large extents of space, time, and taxonomy, thus holding huge potential to fill gaps in global biodiversity monitoring coverage in a cost‐effective way. Yet, the full potential of these data to provide essential indicators of biodiversity change for both research and management remains mostly unrealized, in large part due to the prevailing perception that the lack of standardization presents an unsurmountable barrier. In this paper, we provide an overview of the main challenges of working with unstructured community‐contributed data and synthesize the four fundamental approaches to overcome these challenges and extract useful inferences of biodiversity change, namely: 1) reverse‐engineering survey structure; 2) borrowing strength across taxa; 3) modeling the observation process, and; 4) integrating standardized data sources. To illustrate each of these approaches, we provide examples comparing community‐contributed observations crowdsourced via iNaturalist with long‐term standardized monitoring surveys for a subset of rocky intertidal organisms on the California coast from 2010 to 2019. We conclude by highlighting ways forward for the successful integration of unstructured community‐contributed observations within the global ecosystem of biodiversity change monitoring tools. Our ultimate goal is to update the prevailing perception among researchers and practitioners that unstructured community‐contributed observations of biodiversity are too noisy to use, and help establish this data stream as a key tool for research and management. [ABSTRACT FROM AUTHOR]

Topographic complexity is often considered to be closely associated with habitat complexity and niche diversity; however, complex topography per se does not imply habitat suitability. Rather, ecologically suitable habitats may emerge if topographic features interact with environmental factors and thereby alter their surrounding microenvironment to the benefit of local organisms (e.g., resource provisioning, stress mitigation). Topography may thus act as a key modulator of abiotic stressors and biotic pressures, particularly in environmentally challenging intertidal systems. Here, we review how topography can alter microhabitat conditions with respect to four resources required by intertidal organisms: a source of energy (light, suspended food particles, prey, detritus), water (hydration, buffering of light, temperature and hydrodynamics), shelter (temperature, wave exposure, predation), and habitat space (substratum area, propagule settlement, movement). We synthesize mechanisms and quantitative findings of how environmental factors can be altered through topography and suggest an organism-centered 'form-follows-ecological-function' approach to designing multifunctional marine infrastructure. [Display omitted] • Topography can shape micro-climate through interactions with environmental factors. • Topography-based niches can meet four ecological needs: food, water, shelter, space. • Eco-design may benefit from an organism-centric 'form-follows-function' approach. [ABSTRACT FROM AUTHOR]

The intertidal zone is one of the most stressful environments, with extreme shifts in temperature, salinity, pH and oxygen concentration. Marine molluscs, particularly chitons that belong to the category of ecologically significant organisms, survive in this extreme environment, and are ideal systems for studying stress adaptation. Mitochondria are known to be critical for energy homeostasis, and changes in environmental factors result in their dysfunction and consequent injury to the organism. Intertidal organisms are exception in this respect because they are capable of maintaining mitochondrial integrity. Here, we used mitochondrial genetic components from seven chitons of the intertidal zone to infer phylogenetic relationships. Selection analyses on individual protein-coding genes (PCGs) were performed to identify and map potentially adaptive residues in the modelled structures of the mitochondrial respiratory chain complexes. The results showed significant amino acid changes in sites under diversifying selection for all the PCGs, indicating that the mitochondrial genome in chitons is undergoing adaptive evolution. Such sites were observed in the proton pump as well as in the translocation channel of the transmembrane helices and the surrounding loop regions, thus implying functional modification of the mitochondrial proteins essential for survival in the dynamic environment of the intertidal zone. [ABSTRACT FROM AUTHOR]

Horseshoe crabs may act as mobile substrata for communities of sessile marine organisms on intertidal mudflats. In Singapore, the mangrove horseshoe crabs, Carcinoscorpius rotundicauda (Latreille, 1802) were surveyed for the diversity of epibiotic macrofauna. The most common epibiota observed was the barnacles belonging to Amphibalanus spp., along with other organisms: slipper snails Crepidula walshi and anemones (species undetermined). We also report the first account of an invasive American brackish mussel, Mytella strigata on C. rotundicauda in Singapore. Adult horseshoe crabs, particularly the males, have the highest prevalence and abundance of epibionts. A distinct distribution of epibionts was observed across horseshoe crab gender, age class and between the dorsal and ventral planes. Barnacles were found to be the dominant fouling on dorsal planes, while M. strigata and slipper snails occurred mainly on the ventral planes. [ABSTRACT FROM AUTHOR]

Summary: It is unclear how host‐associated microbial communities will be affected by future environmental change. Characterizing how microbiota differ across sites with varying environmental conditions and assessing the stability of the microbiota in response to abiotic variation are critical steps towards predicting outcomes of environmental change. Intertidal organisms are valuable study systems because they experience extreme variation in environmental conditions on tractable timescales such as tide cycles and across small spatial gradients in the intertidal zone. Here we show a widespread intertidal macroalgae, Fucus distichus, hosts site‐specific microbiota over small (meters to kilometres) spatial scales. We demonstrate stability of site‐specific microbial associations by manipulating the host environment and microbial species pool with common garden and reciprocal transplant experiments. We hypothesized that F. distichus microbiota would readily shift to reflect the contemporary environment due to selective filtering by abiotic conditions and/or colonization by microbes from the new environment or nearby hosts. Instead, F. distichus microbiota was stable for days after transplantation in both the laboratory and field. Our findings expand the current understanding of microbiota dynamics on an intertidal foundation species. These results may also point to adaptations for withstanding short‐term environmental variation, in hosts and/or microbes, facilitating stable host–microbial associations. [ABSTRACT FROM AUTHOR]

Invasive species of intertidal algae drew little attention, even though biological invasions have been a concern around the world. The red algal bangiophyte, Phycocalidia tanegashimensis (I. Shinmura) Santiañez in Santiañez & Wynne, 2020 had been reported from the Southwest Atlantic (Brazil) and Northwest Pacific (Philippines and Japan). The appearance of P. tanegashimensis in Brazil was believed to be a recent introduction from the Indo-Pacific/North Pacific but without conclusive evidence. During a study of the biodiversity of bladed Bangiales in South China and Vietnam, we detected the presence of P. tanegashimensis in these areas using a molecular approach to the identification of the species. New distributional records of P. tanegashimensis were therefore morphologically and molecularly confirmed along the Chinese and Vietnamese coastline (part of the South China Sea) in the present study. Molecular sequence data using rbcL (ribulose bisphosphate carboxylase/oxygenase large subunit), COI-5P (cytochrome oxidase 1), and 18S rRNA genes placed P. tanegashimensis in a clade with P. acanthophora (E.C.Oliveira & Coll) Santiañez in Santiañez & Wynne, 2020, P. denticulata (Levring) Santiañez & M.J.Wynne, 2020, P. suborbiculata (Kjellman) Santiañez & M.J.Wynne, 2020 and P. vietnamensis (Tak.Tanaka & Pham) Santiañez & M.J.Wynne, 2020 as out-groups. The common morphological characters found in these species, including lobed blades and marginal denticulation, and subtropical/tropical distribution, were discussed in relation to their phylogeny. Haplotype distribution analysis indicated that P. tanegashimensis in Brazil might be an invasive species from the South China Sea. The arrival time of P. tanegashimensis from the South China Sea to Brazil was also discussed. [ABSTRACT FROM AUTHOR]

Glacier retreat is a major long-standing global issue; however, the ecological impacts of such retreats on marine organisms remain unanswered. Here, we examined changes to the polar benthic community structure of "diatoms" under current global warming in a recently retreated glacial area of Marian Cove, Antarctica. The environments and spatiotemporal assemblages of benthic diatoms surveyed in 2018–2019 significantly varied between the intertidal (tidal height of 2.5 m) and subtidal zone (10 and 30 m). A distinct floral distribution along the cove (~ 4.5 km) was characterized by the adaptive strategy of species present, with chain-forming species predominating near the glacier. The predominant chain-forming diatoms, such as Fragilaria striatula and Paralia sp., are widely distributed in the innermost cove over years, indicating sensitive responses of benthic species to the fast-evolving polar environment. The site-specific and substrate-dependent distributions of certain indicator species (e.g., F. striatula, Navicula glaciei, Cocconeis cf. pinnata) generally reflected such shifts in the benthic community. Our review revealed that the inner glacier region reflected trophic association, featured with higher diversity, abundance, and biomass of benthic diatoms and macrofauna. Overall, the polar benthic community shift observed along the cove generally represented changing environmental conditions, (in)directly linked to ice-melting due to the recent glacier retreat. [ABSTRACT FROM AUTHOR]

Marine coasts are dynamic environments where spatial-physical gradients interact with seasonality. In the Patagonia in particular, high temperatures and strong winds lead to stressing physical conditions that shape intertidal communities. In a previous study, we found that the interaction between the sponge Hymeniacidon perlevis and the macroalga Ulva lactuca was context-dependent, switching from positive at the harsher intertidal to negative at the milder subtidal environment. Temporal variation in the physical variables, however, may also affect species performance and interaction strength. Since Patagonian shores are strongly seasonal environments, we evaluated how the interactions (competitive or cooperative) among these two spatially dominant species changed over a temporal-stress gradient throughout a year. We predicted that the macroalga would facilitate the sponge in seasons with more severe environmental conditions, whereas negative or neutral interactions would prevail when environmental conditions were milder. Our results demonstrated that the sign and intensity of the interaction between Hymeniacidon and Ulva changed over the seasons and coincided with a hump-shaped model, involving a neutral interaction in the milder seasons of autumn and winter, then switching to a positive one in the inclement springtime, and finally shifting to a negative relationship in the harshness of the summer. The amelioration of stressful conditions through shading did not satisfactorily explain the underlying mechanism for this varying interaction, an aspect that still remains unclear. Nevertheless, several mechanisms are discussed both within the context of the stress gradient hypothesis and the specific physiological constraints of intertidal organisms. [ABSTRACT FROM AUTHOR]

Increases in global temperatures are expected to have dramatic effects on the abundance and distribution of species in the coming years. Intertidal organisms, which already experience temperatures at or beyond their thermal limits, provide a model system in which to investigate these effects. We took advantage of a previous study in which experimental plates were deployed in the intertidal zone and passively warmed for 12 years to a daily maximum temperature on average 2.7°C higher than control plots on the adjacent bedrock. We compared the composition of the biological communities on each experimental plate with its neighboring bedrock control. Plate communities showed decreased richness of taxa and percent cover of filamentous algae, mussels and mobile grazers relative to bedrock, and increased percent cover of biofilm. We then used short‐term time‐series measurements of plate and bedrock temperatures and a mechanistic heat‐budget model to hindcast those temperatures back 12 years. Greater differences in long‐term average temperature between the experimental plates and bedrock controls were correlated with lower similarity in community composition. Additionally, years with higher average differences between plate and bedrock temperatures were more predictive of current compositional similarity between plate and bedrock communities, even though they occurred farther in the past than did more recent, but cooler, years. We conclude that current intertidal communities reflect their long‐term, rather than short‐term, thermal histories. Mechanistic heat‐budget models based on short‐term measurements can provide this valuable, long‐term information. [ABSTRACT FROM AUTHOR]

Aim: Understanding patterns in the abundance of species across thermal ranges can give useful insights into the potential impacts of climate change. The abundant‐centre hypothesis suggests that species will reach peak abundance at the centre of their thermal range where conditions are optimal, but evidence in support of this hypothesis is mixed and limited in geographical and taxonomic scope. We tested the applicability of the abundant‐centre hypothesis across a range of intertidal organisms using a large, citizen science‐generated data set. Location: UK. Methods: Species' abundance records were matched with their location within their thermal range. Patterns in abundance distribution for individual species, and across aggregated species abundances, were analysed using Kruskal–Wallis tests and quantile general additive models. Results: Individually, invertebrate species showed increasing abundances in the cooler half of the thermal range and decreasing abundances in the warmer half of the thermal range. The overall shape for aggregated invertebrate species abundances reflected a broad peak, with a cool‐skewed maximum abundance. Algal species showed little evidence for an abundant‐centre distribution individually, but overall the aggregated species abundances suggested a hump‐backed abundance distribution. Main Conclusions: Our study follows others in showing mixed support for the abundant‐centre hypothesis at an individual species level, but demonstrates an increased predictability in species responses when an aggregated overall response is considered. [ABSTRACT FROM AUTHOR]

When it comes to bonding in an aqueous environment, intertidal marine organisms such as mussels, sandcastle worms, barnacles and polychaetes are providing inspiration for the assembly of synthetic molecules into the polymeric adhesives. Although intense demands in various life or industrial applications and many mussel-inspired systems have been shown to develop coatings and hydrogels, exploring the mimetic mussel adhesive system through the control of composition and polymer molecular weight is demonstrated less often. In this report, we showed a simple approach to synthesize mussel-inspired adhesive, P(N-butyl acrylate-co-l-Dopa-methacrylate anhydride), which possesses characteristics of simple synthesis, easy-using, no extra-crosslinker need, and excellent adhesion behaviour on diverse substrates. Adhesion behaviour was examined using low- and high-surface-energy substrates (e.g. PTFE and steel, respectively). Furthermore, the fabricated adhesives exhibited excellent underwater adhesive behaviour for steel in various aqueous solutions, including ion ((IO4)− and Mn3+), acid and alkali solutions (pH = 4, 6.7 and 8, respectively). The outstanding fabricated adhesives take advantage of the catechol functionality and wettability of the resulting polymer. These insights should help us to design next-generation underwater adhesive systems as well as open up a number of future research designs for mussel-inspired adhesives with performance not accessed previously. [ABSTRACT FROM AUTHOR]

African penguins (Spheniscus demersus) are pursuit-diving seabirds endemic to the coast of southern Africa. In this study, we investigate the presence of seashells and anthropogenic debris (e.g. plastic, glass, nylon) in the stomach contents of adult African penguins, as determined from sampling of live penguins through the water off-loading technique (n = 4,793) and from post-mortem examination of penguin carcases (n = 159). Seashells were present in stomach contents sampled from 106 live (2.2%) and three dead (1.9%) penguins. Seashells originated from a variety of intertidal and subtidal organisms including molluscs, barnacles and bryozoans, and the eroded condition of the shell fragments suggests that they were picked up from shell deposits on the beach or in the surf zone. Seashell ingestion appears to be more frequent in the months of peak egg laying. A subset of stomach samples from known-sex individuals revealed that seashells were only present in the stomachs of adult females. In post-mortem examination, the presence of seashells in the stomach was accompanied by anatomical evidence that egg laying was imminent or had recently occurred. Anthropogenic debris was found in one (0.6%) and eight (0.2%) stomach content samples obtained from dead and live penguins, respectively. In some cases, the ingestion of anthropogenic debris co-occurred with that of seashells, and their size and shape were similar. Our findings demonstrate that adult female African penguins occasionally ingest seashells, possibly as a calcium supplementation strategy, and raise concern that in doing so they may also accidentally ingest anthropogenic debris. [ABSTRACT FROM AUTHOR]

Plastic products are widely distributed worldwide and continue to have a negative impact on the environment and organisms. Intertidal regions, which interface between upland and marine ecosystems, are regions of high ecological importance and serve as repositories for a variety of plastic wastes. However, ecological risk assessments of microplastics (MPs) in these transitional environments are still scarce. In this study, the morphological characteristics and spatial distribution of MPs in the intertidal surface sediments of Haizhou Bay were analyzed, and an ecological risk assessment framework for MPs was developed. Overall, the average abundance of MPs in the sediments was 2.31 ± 1.35 pieces/g dw. The size of the MPs was mainly less than 1 mm, and the main shape, color and polymer type of the MPs were mainly fibrous (58%), blue (30%), and PVC (22%), respectively. Cluster analyses showed that the sites could be well distinguished by size and polymer type but not by MP shape and color. According to the hazard scores, most of the sites in this area belonged to a risk level of IV, while the pollution loading index (PLI) showed that most of the sites belonged to a risk level of II. The ecological toxicity risk from the species–sensitive distribution (SSD) model showed that one–third of the sites had ecological MPs toxicity risks to marine organisms. We believe that normalized and standardized assessment methods should be implemented to monitor and manage the risk of MPs in the intertidal sediments. Particularly, the multiple dimensions, standard abundance of MPs, as well as MPs ingestion in the intertidal organisms, should be fully considered in the next step. [Display omitted] • a new framework was used to describe the ecological risk assessment of MPs. • a risk criterion was used to assess the pollution status of intertidal zones. • an enhancement was supplemented to the MP pollution database. [ABSTRACT FROM AUTHOR]

Sediment transport and resuspension are essential processes in soft-sediment environments that mediate shellfish population dynamics, water column turbidity, and estuary geomorphology at multiple scales. Adult cockles, Austrovenus stutchburyi (in New Zealand), are key organisms on intertidal sand flats that influence sediment properties, and their removal could impact the stability of the seabed and affect crucial feedback processes in this system. We conducted a field experiment to explore our hypothesis that the loss of adult cockles will increase sediment transport and resuspension non-linearly. Changes in sediment transport regimes will then influence the properties of sediment such as grain size, organic content, and chlorophyll a content. We also expected that the direction and magnitude of this effect would depend on the varying environmental characteristics across the sites, such as hydrodynamic activity and sediment grain size. We excluded adult cockles from 3 × 3 m intertidal plots at 15 sites across a natural adult cockle density gradient (300–3500 ind/m2). After seven months, sediment traps were deployed in exclusion and control plots to measure the sediment transported over two tidal cycles associated with the bedload and water column with differing densities of adult cockles. Adult cockle density was a significant predictor in all models to explain sediment transport and accounted for the largest proportion of variability explained. Relationships between cockle density and sediment transport changed between sites and over time. In these situations, simple linear relationships were not always apparent due to the interacting effects of cockle density, hydrodynamic process, and sediment characteristics. The influence of adult cockles on sediment transport was also affected by the standing stock of microphytobenthos and interacted with the mud content in their surrounding environment. Our study demonstrates the existence of an important feedback between adult cockle density, sediment stability and sediment transport that is mediated by hydrodynamic processes and sediment characteristics. • We used traps to measure sediment transport across a cockle density gradient. • Changes in adult cockle densities alters sediment stability non-linearly. • Adult cockles interact with their environment to drive sediment transport processes. • Sediment transport is highly context-dependent, influenced by physical processes. [ABSTRACT FROM AUTHOR]