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Strain LCG007, isolated from Lu Chao Harbor's intertidal water, phylogenetically represents a novel genus within the family Rhodobacteraceae. Metabolically, it possesses a wide array of amino acid metabolic genes that enable it to thrive on both amino acids or peptides. Also, it could hydrolyze peptides containing D-amino acids, highlighting its potential role in the cycling of refractory organic matter. Moreover, strain LCG007 could utilize various carbohydrates, including mannopine and D-apiose—compounds primarily derived from terrestrial plants—demonstrating its capacity to degrade terrestrial organic matter. It could assimilate ammonia, nitrate and nitrite, and utilizes organic nitrogen sources such as polyamines, along with diverse organic and inorganic phosphorus and sulfur sources. Importantly, unlike very limited Sulfitobacter species that possess photosynthetic genes, the genomes of strain LCG007-affiliated genus and all Roseobacter species harbor photosynthetic gene clusters. This conservation was further supported by the significant impact of light on the growth and cell aggregation of strain LCG007, suggesting that acquirement of photosynthetic genes could play a crucial role in the speciation of their common ancestor. In terms of environmental adaptability, the genes that encode for DNA photolyase, heat and cold shock proteins, and enzymes responsible for scavenging reactive oxygen species, along with those involved in the uptake and biosynthesis of osmoprotectants such as betaine, γ-aminobutyric acid (GABA), and trehalose collectively enable strain LCG007 to survive in the dynamic and complex intertidal zone environment. Besides, the capacity in biofilm formation is crucial for its survival under conditions of oligotrophy or high salinity. This study enhances our comprehension of the microbial taxonomy within the Roseobacter clade affiliated cluster, their survival strategies in intertidal ecosystems, and underscores the significance of their role in nutrient cycling. It also highlights the crucial importance of photosynthetic metabolism for the speciation of marine bacteria and their ecological resilience. [ABSTRACT FROM AUTHOR]

Bae, J. and Sherman, D.J., 2025. Microscale morphologic changes caused by groundwater seepage on a macrotidal beach. Journal of Coastal Research, 41(1), 16–26. Charlotte (North Carolina), ISSN 0749-0208. Beach groundwater dynamics and groundwater seepage (exfiltration) are important agents of morphologic change in the intertidal zone and are controlled mainly by the relationships between local water level, the elevation of beach water table, and the permeability of beach sediments. Groundwater seepage can alter sediment transport processes on beaches through regulating saturation on the beach face and generating shear stresses sufficient to initiate sediment transport. This study investigates seepage dynamics in the context of a macrotidal beach and consequent erosion, deposition, and seepage-induced morphologic changes. Data were collected from the west coast of South Korea, at Hakampo Beach, where the spring, mean, and neap tide ranges are 6.5, 4.6, and 2.8 m, respectively. Beach morphology and changes were measured using terrestrial LiDAR. Beach groundwater levels were measured with a series of wells. Sand samples were taken and analyzed to characterize beach face texture and to estimate beach permeability. The water table and sediment data were used to estimate seepage flows at low water, using Darcy's law. The relationship between seepage rates and morphologic changes was examined with geographically weighted regression analysis. The results show that seepage-induced offshore transport occurred in the intertidal zone below groundwater seepage lines during spring tide, whereas transport was concentrated along seepage-induced tidal rills during neap tide. This highlights the importance of recognizing the variability in seepage discharge with different tidal ranges, especially in the context of potential flow rates exceeding the threshold for sediment transport. This study also points to the control of breaks in beach face slope and concomitant changes in grain size in the location of the groundwater seepage line in macrotidal environments. [ABSTRACT FROM AUTHOR]

The intertidal zone, a dynamic interface of marine, atmospheric, and terrestrial ecosystems, exposes microorganisms to rapid shifts in temperature, salinity, and oxidative stress. Strain LCG004, representing a novel Palleronia species, was isolated from the Lu Chao Harbor's intertidal seawater in the Western Pacific Ocean. The genome of the organism reveals its metabolic versatility, enabling the utilization of various organic substrates—ranging from organic acids, amino acids, to sugars, and encompassing complex carbohydrates—as well as adept handling of inorganic nutrients, thereby highlighting its significant role in the cycling of nutrients. The strain is equipped with multiple osmoprotectant transporters, deoxyribodipyrimidine photo-lyase, and a comprehensive antioxidant defense system, featuring with multiple catalases, peroxidases, and superoxide dismutases, enabling it to withstand ever-changing environmental conditions, UV radiation, and oxidative challenges. Notably, LCG004 exhibited enhanced growth and cell aggregation under oligotrophic conditions, promoted by light exposure, underscoring the significant influence of light on its morphological and physiological attributes. This study elucidates strain LCG004's metabolic characteristics and ecological potential, and offers insights into its contributions to biogeochemical cycles and survival strategies in one of nature's most fluctuating environments. [ABSTRACT FROM AUTHOR]

Coastal algal reef ecosystems, which are formed by the skeletal carbonate of crustose coralline algae (CCA), provide vital habitats for a diverse range of marine organisms and serve as valuable archives of long‐term environmental data. Despite the importance of these reef ecosystems, there is currently a lack of available information regarding the accretion rates of CCA in subtropical intertidal zones in the Taoyuan algal reef. We measured the vertical accretion and horizontal growth of CCA cultured in two aquaculture tanks over a 9‐month period. The vertical accretion and horizontal growth rate of CCA was approximately 0.29–0.43 and 5.5 μm·day−1 (the extrapolated annual value is equivalent to 0.11–0.16 and 2.0 mm·year−1, respectively). Newly colonized CCA had faster horizontal growth of approximately 110 μm·day−1 (equivalent to 40.2 mm·year−1). These results highlight the slow and gradual process of algal reef ecosystem formation in the subtropical intertidal zones. The CCA had a faster lateral growth rate as seen in the newly settled CCA. These findings contribute to our understanding of the overall growth dynamics of CCA. [ABSTRACT FROM AUTHOR]

A new marine epipsammic diatom species, Cymbellonitzschia biseriata C.H. Li, H.H. Liu, Y.H. Gao & C.P. Chen sp. nov. from Fujian Province, China, is described, and is the first record of this genus in China. The morphological observations and species description are based on scanning electron microscopy and light microscopy. The main characteristics of C. biseriata are as follows: valves are semi-lanceolate; striae are biseriate or change from uniseriate to biseriate; canal raphe is located and discontinuous on the ventral side; distal raphe ends are curved and extended to the dorsal side of the valve, forming raised helictoglossae; areolae are occluded by domed hymenes; girdle consists of 4–7 perforated bands. The new species is only known at present from its type locality, Weitou Bay, Quanzhou City, Fujian Province, China. [ABSTRACT FROM AUTHOR]

Mudflat wetland, one of the 27 surface elements identified by the International Geographic Data Committee, has undergone substantial transformations with the rapid growth of the social economy and marine hazards, resulting in significant changes in its area and distribution. Quick identification of mudflat wetland evolution is vital to improve the mudflat ecological service value. We employed object-oriented and decision tree classification methods to map the mudflat wetland in the Yellow Sea using the Landsat time series from 1983 to 2020. The Improved Spectral Water Index (IWI) was established by combining the characteristics of many ratio indices and using ratio operation and quadratic power operation. The coefficient of variation (CV) of the IWI was calculated, and the range of the intertidal zone in 1983, 1990, 2000, 2010, and 2020 was obtained by using a threshold method. The results indicate that the mudflat wetland area decreased continuously from 1983 to 2020, with a reduction of 337.38 km2/10a. Among the total area, the natural wetland experienced a decline of 446.9 km2/10a, with the most drastic changes occurring between 2000 and 2010. In contrast, the area of the human-made wetland increased by 109.56 km2/10a. Over the 38 years, the tidal flat has undergone the most drastic reduction, with an average of 157.45 km2/10a. From 1983 to 2020, the intertidal zone area decreased, with a reduction of 429.02 km2/10a. Human activities were the key factors causing mudflat wetland loss. Based on these findings, we propose several policy suggestions. This study provides a scientific basis for understanding the synergetic evolution mechanism of coastal resources utilization and mudflat wetland protection under global change. [ABSTRACT FROM AUTHOR]

The intertidal mussel Perumytilus purpuratus exhibits phenotypic plasticity in response to predation threats, with these responses influenced by the mussels' perception of predation risk. These adaptations, however, are constrained by energy costs and interactions with environmental factors that may trigger synergistic effects or trade-offs among different fitness traits. In particular, this study focuses on the antipredatory responses of P. purpuratus against the sea star Meyenaster gelatinosus, examining how the presence of the predator and water flow strength influence these responses. The research was conducted through laboratory experiments, comparing mussels from two distinct localities with varying predation risks posed by M. gelatinosus: Punta Hualpén, where the predator is naturally present, and Coliumo, where it is absent. The anti-predatory responses were assessed by measuring attachment strength, byssus production, and adductor muscle mass in the presence of predator cues. Additionally, potential costs associated with these responses were estimated using the gonadosomatic index as a measure of reproductive investment. The findings indicate that the anti-predatory responses of P. purpuratus are contingent on the mussel's origin, with adhesion strength and byssus production negatively impacting reproductive investment. Moreover, the study highlights the intricate interplay of multiple factors, as evidenced by the complex adaptive mechanisms observed in P. purpuratus. The interaction between predator presence and water flow strength and their combined effects on various traits underscores the need for comprehensive multifactorial experiments to understand these adaptive processes. In conclusion, this study provided valuable insights into the nuanced and site-specific nature of anti-predatory responses in P. purpuratus. The research emphasizes the importance of considering multiple factors and conducting comprehensive experiments to unravel the intricacies of adaptive mechanisms in prey species. [ABSTRACT FROM AUTHOR]

Plant size is closely linked to its leaf trait characteristics, which are essential for determining its form and function. These relationships constitute a fundamental component of the global spectrum of plant diversity. Despite this, the size–trait relationships in coastal mangroves have often been overlooked, with a common assumption that they would mirror those found in terrestrial tropical trees. However, recent studies have begun to challenge this assumption, revealing unique adaptations and trait variations in mangroves that are influenced by their specific environmental conditions, such as salinity and nutrient availability. In this research, we investigated the leaf structural traits, plant height, and diameter at breast height or basal height (DBH) of 10 shrub and tree species. This study was carried out along an intertidal gradient within a mangrove forest located in Southeast China. We found that leaf traits differed significantly between shrubs and trees in their response to intertidal gradients, indicating that different species have evolved specific adaptations to thrive in their respective intertidal zones. This insight can help us decipher the selective pressures that have shaped trait evolution. Among all species, leaf carbon (C) economics (leaf dry mass content, leaf mass per area, and leaf density) decreased significantly with increasing plant height and DBH. For each growth form and intertidal zone, the relationships between plant size (height or DBH) and leaf C economics traits were consistent with those in the pooled dataset. Our study reveals that mangrove plants exhibit size‐related adjustments in leaf C economic strategies, indicating that plant size potentially acts as a proxy for the "slow–fast" continuum of plant performance. This discovery is pivotal for advancing our understanding of plant functional ecology and for enhancing the precision of global C cycle models, which are highly responsive to perturbations in atmospheric CO2 and climate change. [ABSTRACT FROM AUTHOR]

The intertidal zone, a dynamic interface between the ocean and land, is one of the most diverse ecological habitats and harbors some of the richest biological communities. However, due to its unique location at the water's edge, it also bears the brunt of human activities in coastal areas. Intertidal biological resources serve as a foundation for the survival of coastal residents and plays a crucial role in coastal economic development. However, the intertidal zone serves as a primary area for coastal zone development and utilization, facing unprecedented environmental pressure resulting from rapid industrialization, urbanization, and agricultural intensification along coastlines. Consequently, safeguarding the intertidal ecological environment and biodiversity has become imperative for China's marine ecological civilization construction efforts. The coastal substrates in Qingdao encompass a diverse range of types, with predominantly rocky, sandy, and silt-muddy coasts constituting its coastline features. As an important marine center city encompassing coastal resorts and international port cities in China, Qingdao has witnessed rapid growth in its marine industry sector, while experiencing mounting pressure on its intertidal ecosystem. Shellfish are the predominant biological group in Qingdao's intertidal zone, exhibiting significant variation in species composition and community characteristics across different coastal types, thus serving as crucial ecological indicators for this zone. Despite a relatively early start to research on shellfish resources in Qingdao's intertidal zone, recent surveys focusing on shellfish distribution across various substrates are limited.To comprehensively assess the resource status and community structure of intertidal shellfish along the Qingdao coast, this study investigated intertidal shellfish resources at eight representative stations, including rocky, sandy, silt-muddy, and mixed sandy-rocky coastal types in May and October 2022. The composition of shellfish species, dominance patterns, and community structure parameters, including the Shannon-Wiener diversity index, Margalef richness index, and Pielou evenness index, were compared and analyzed at each station. Community clustering analyses were performed using similarity coefficient clustering and non-metric multi-dimensional scaling techniques. Our findings revealed in total 40 identified species of intertidal shellfish along the Qingdao coast. Among the stations surveyed for species richness, Canyon Street exhibited the highest number, with 18 species recorded, whereas Jinkou had the lowest, with only six species observed. The dominant species composition varied among survey stations and showed seasonal variations in type and dominance. During spring, Littorina brevicula, Mya arenaria, and Patelloida pygmaea emerged as the dominant species, whereas Crassostrea gigas, Musculista senhousia, and Ruditapes philippinarum dominated during fall. The Shannon-Wiener diversity index ranged from 0.85 to 1.84 and 0.66 to 2.00, Margalef richness index ranged from 0.86 to 1.97 and 0.62 to 2.96, and Pielou evenness index ranged from 0.41 to 0.84 and 0.31 to 0.98 in spring and autumn, respectively. Qiantaoyuan in Langya, Aoshanwei, and Cangkou exhibited the highest Shannon-Wiener diversity and Margalef richness indices among all stations. Community clustering results varied between spring and autumn at each station. Hongshiyi and Jinkou consistently formed separate branches, Cangkou and Wanggezhuang always clustered together, and the former Taoyuan in Langya and Aoshanwei were consistently grouped together. This study revealed that substrate type significantly influenced the composition and community structure characteristics of intertidal shellfish in Qingdao. This study identifies the status of shellfish resources on various substrates within Qingdao's intertidal zone, providing a foundation for resource development, protection, and ecological restoration efforts.

Two novel Gram-stain-negative, aerobic, and non-motile strains, designated FZY0004T and YYF002T, were isolated from an agar-degrading co-culture, which was obtained from seawater of the intertidal zone of Yancheng City, the Yellow Sea of China. Strain FZY0004T optimally grew at 28 °C, pH 7.0, and 2–6% NaCl, while strain YYF002T optimally grew at 28 °C, pH 7.5, and 2–4% NaCl. Strain FZY0004T possessed Q-9 as the major respiratory quinone, and its major fatty acids (> 10%) were summed feature 8 (C18:1ω7c), C16:0, and summed feature 3 (C16:1ω7c/C16:1ω6c). The polar lipids identified in strain FZY0004T were phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and several unidentified phospholipids (PL) and lipids (L). On the other hand, strain YYF002T had MK-6 as the predominant respiratory quinone and its major fatty acids consisted of iso-C15:0, iso-C15:1 G, and iso-C15:0 3-OH. The polar lipids identified in strain YYF002T were aminolipid (AL), PE, and several unidentified lipids. Strain FZY0004T shared 99.5% 16S rRNA gene sequence similarity and 90.1% average nucleotide identity (ANI) with T. povalilytica Zumi 95T, and strain YYF002T shared 99.2% 16S rRNA gene sequence similarity and 88.2% ANI with W. poriferorum JCM 12885T. The genomic DNA G + C contents of strains FZY0004T and YYF002T were 54.5% and 33.5%, respectively. The phylogenetic, phenotypic, and physiological characteristics permitted the distinction of the two strains from their neighbors, and we thus propose the names Thalassospira aquimaris sp. nov. (type strain FZY0004T = JCM 35895T = MCCC 1K08380T) and Winogradskyella marincola sp. nov. (type strain YYF002T = JCM 35950T = MCCC 1K08382T). [ABSTRACT FROM AUTHOR]

In this study, we reported a Gram-stain-negative, ovoid to rod-shaped, atrichous, and facultative anaerobe bacteria strain named YMD61T, which was isolated from the intertidal sediment of Yangma island, China. Growth of strain YMD61T occurred at 10.0–45.0 °C (optimum, 30.0 °C), pH 7.0–10.0 (optimum, 8.0) and with 0–3.0% (w/v) NaCl (optimum, 2.0%). Phylogenetic tree analysis based on 16 S rRNA gene or genomic sequence indicated that strain YMD61T belonged to the genus Fuscovulum and was closely related to Fuscovulum blasticum ATCC 33,485T (96.6% sequence similarity). Genomic analysis indicated that strain YMD61T contains a circular chromosome of 3,895,730 bp with DNA G + C content of 63.3%. The genomic functional analysis indicated that strain YMD61T is a novel sulfur-metabolizing bacteria, which is capable of fixing carbon through an autotrophic pathway by integrating the processes of photosynthesis and sulfur oxidation. The predominant respiratory quinone of YMD61T was ubiquinone-10 (Q-10). The polar lipids of YMD61T contained phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, five unidentified lipids, unidentified aminolipid and unidentified aminophospholipid. The major fatty acids of strain YMD61T contained C18:1ω7c 11-methyl and summed feature 8 (C18:1ω 7c or/and C18:1ω 6c). Phylogenetic, physiological, biochemical and morphological analyses suggested that strain YMD61T represents a novel species of the genus Fuscovulum, and the name Fuscovulum ytuae sp. nov. is proposed. The type strain is YMD61T (= MCCC 1K08483T = KCTC 43,537T). [ABSTRACT FROM AUTHOR]

The organic carbon sequestered by the world's mangrove forests plays a key role in the global carbon cycle and may be central to climate change mitigation. This is because mangroves typically exhibit high rates of net primary production and greater carbon sequestration capacity compared to terrestrial ecosystems. This study investigated the influence of selected soil physicochemical properties on the soil organic carbon (SOC) content of Rekawa mangrove forest, Sri Lanka. The effect of soil pH, salinity, conductivity, moisture content (%), bulk density, porosity, phosphate, and nitrate content on SOC was examined along an intertidal gradient. Results showed, SOC was positively correlated with salinity (r2= 0.74), conductivity (r2= 0.76), moisture content (r2= 0.76), porosity (r2= 0.92), and phosphate content (r2= 0.74) while SOC was negatively correlated with bulk density (r2= -0.92) across the entire intertidal zone. Generalised Linear Model (GLM) resolved SOC to be best predicted as a function of soil porosity and soil moisture content [Akaike Information Criterion (AIC): 142.04], with other soil properties modulating the results within some zones. Overall, the present study shows that specific consideration of soil physicochemical properties could allow improved estimates of total carbon stocks which are becoming increasingly important for carbon accounting and national inventories. [ABSTRACT FROM AUTHOR]

Copyright of Sultan Qaboos University Journal for Science is the property of Sultan Qaboos University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The report provides new data on Vaucheria vipera Blum, one of the rarest collected marine species. In 2023, V. vipera was discovered in the littoral zone of the Unskaya Inlet of the White Sea. The record is considered first in Russia and the Arctic Ocean. The study of the morphology of specimens from the White Sea allowed to expand the morphological range of the species in terms of the maximum dimensions of oogonia, oospores, and antheridia. The work also pays attention to the basal septa that separate short branches bearing the gametangia. Based on the morphology of the gametangia, it is proposed to transfer this species to the section Woroninia. [ABSTRACT FROM AUTHOR]

Intertidal mussels experience prolonged emersion during low tide, followed by rapid submergence cooling during high tide, causing temperature-induced stress responses. This study examined variations in heart rate to investigate the relationship between emerged and submerged thermal stress in Mediterranean mussels Mytilus galloprovincialis and brown mussels Perna perna from one site on a south coast warm-water coastline and two sites on a west coast cold-water coastline in South Africa. Gaping behaviour in air displayed by P. perna appears to contribute towards their survivability under warmer conditions, as their flatline temperature was higher as compared with M. galloprovincialis, which do not display gaping behaviour. Warm-water acclimatised mussels of both species appeared better able to survive higher temperatures than cold-water acclimatised mussels. However, both mussel species are possibly living at their upper thermal tolerance based on their sublethal Arrhenius breakpoint temperature (ABT). The values of ABT were higher while exposed to air than when submerged, revealing physiological mechanisms at work to cope with changes in the intertidal zone. [ABSTRACT FROM AUTHOR]

Fiddler crabs have been used as model organisms in many laboratory and field studies. In their natural environment, social interaction with other fiddler crabs (conspecific or heterospecific) is recurrent, but manipulative studies involving these crabs as models are often performed with isolated individuals. The isolation of an animal can interfere in the behaviors recorded as response variables. Thus, the aim of this study was to evaluate whether the presence of other individuals affects the performance of behaviors of fiddler crabs Leptuca uruguayensis. We tested two hypotheses in the field: (1) the visual stimulus of the crab assemblage affects the activity of male fiddler crabs; and (2) the presence of other conspecific affects the activity of male fiddler crabs depending on the sexes of the individuals present. We found the activities of L. uruguayensis males mediated by social interactions does not depend exclusively on visual stimuli. Physical interaction with other conspecifics of both sexes enables the perception of stimuli which can influence the waving behavior of L. uruguayensis males. We suggest that behavioral studies with this model should consider the presence of other individuals. Understanding the behavioral complexity of a model organism contributes to more robust experiments with greater control of interfering variables. [ABSTRACT FROM AUTHOR]

In coastal environments, eutrophication and ocean acidification both decrease pH, impacting the abiotic conditions experienced by marine life. Infaunal invertebrates are exposed to lower pH conditions than epifauna, as porewater pH is typically lower than the overlying water. We investigated the effects of altering sediment carbonate chemistry, through the addition of transplanted green algae and/or crushed shell hash, on an infaunal community. This factorial field experiment was conducted on an intertidal mudflat in the Bay of Fundy, New Brunswick, from July to September of 2020. After 1 month, sediment pH was increased across all depths (0.09 ± 0.03 pH units, or 0.84–2.5%) by the shell hash, but was not affected by the algae, while the multivariate community composition was impacted by an interaction between algae and experimental block (6.9% of variation) as well as shell hash treatment (2.7% of variation). After month 2, all responses to the treatments disappeared, likely due to tidal currents washing away some of the shell hash and algae, suggesting reapplication of the treatments is needed. Most of the variation in the community composition was explained by spatial variation in the treatment replicates among the treatment blocks (33.5% of variation). Despite the small effects of the experimental treatments on sediment carbonate chemistry, distance-based linear modeling indicated that sediment pH may be an important driver of variation in the infaunal community. Given the complexity of the processes driving sediment chemistry in coastal environments, further experiments exploring changing environmental conditions that drive infaunal marine community structure are required. [ABSTRACT FROM AUTHOR]

Background: The marine environment harbors high biodiversity; however, it is poorly understood. Nucleotide sequence data of all marine organisms should be accumulated before natural and/or anthropogenic environmental changes jeopardize the marine environment. In this study, we report a cost-effective and easy DNA barcoding method. This method can be readily adopted without using library preparation kits. It includes multiplex PCR of short targets, indexing PCR, and outsourcing to a sequencing service using the NovaSeq system. Methods and results: We targeted four mitochondrial genes [cytochrome c oxidase subunit I (COI), COIII, 16S rRNA (16S), and 12S rRNA (12S)] and three nuclear genes [18S rRNA (18S), 28S rRNA (28S), internal transcribed spacer 2 (ITS2)] in 95 marine invertebrate specimens, which were primarily annelids. The primers, including adapters and indices for NovaSeq sequencing, were newly designed. Two PCR runs were conducted. The 1st PCR amplified specific loci with universal primers and the 2nd added sequencing adapters and indices to the 1st PCR products. The gene sequences obtained from the FASTQ files were subjected to BLAST search and phylogenetic analyses. One run using 95 specimens yielded sequences averaging 2816 bp per specimen for a total length of six loci. Nuclear genes were more successfully assembled compared with mitochondrial genes. A weak but significantly negative correlation was observed between the average length of each locus and success rate of the assembly. Some of the sequences were almost identical to the sequences obtained from specimens collected far from Japan, indicating the presence of potentially invasive species identified for the first time. Conclusions: We obtained gene sequences efficiently using next-generation sequencing rather than Sanger sequencing. Although this method requires further optimization to increase the success rate for some loci, it is used as a first step to select specimens for further analyses by determining the specific loci of the targets. [ABSTRACT FROM AUTHOR]

Saltwater‐freshwater mixing zones in beach aquifers support biogeochemical reactions that moderate chemical loads in fresh groundwater discharging to marine ecosystems. Existing laboratory and numerical modeling studies have demonstrated that fluid density gradients in the mixing zone can lead to free convection and the formation of density instabilities, or salt fingers, under a range of hydrologic, morphologic, and hydrogeologic conditions. However, salt fingers have rarely been observed in real‐world beach aquifers despite a growing body of field studies investigating intertidal mixing zones. In this study, we used geostatistical methods to generate randomly distributed assemblages of fine and medium sand and incorporated those geologic realizations into variable‐density variably‐saturated flow and salt transport simulations to explore the influence of geologic structure on mixing zone stability in tidally‐influenced beaches. Ensemble‐averaged model results show that geologic heterogeneity inhibits salt finger formation and promotes a stable intertidal mixing zone due to enhanced dispersion. This effect is highest for high degrees of heterogeneity and for more laterally connected geologic architecture. Compared to hydraulically equivalent homogeneous models, sediments with moderate to high heterogeneity produce mixing zones that are on average 19%–29% smaller and 3–10 times more stable due to the absence of the downward convection and seaward movement of salt fingers. The models indicate that geologic heterogeneity may explain the lack of field observations of salt fingers in real‐world intertidal mixing zones. The findings have implications for predicting the onset of free convection in beaches and for understanding intertidal pore water biogeochemistry and chemical fluxes to the ocean. Key Points: Geologic heterogeneity inhibits salt finger formation in beach aquifers and promotes a stable mixing zone due to enhanced dispersionIntertidal saltwater‐freshwater mixing zones are most stable under high degrees of heterogeneity and high geologic continuityResults provide a possible explanation into the lack of field observations of fingering flow in beach aquifers [ABSTRACT FROM AUTHOR]

Copyright of South China Fisheries Science is the property of South China Fisheries Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Strain LCG007, isolated from Lu Chao Harbor's intertidal water, phylogenetically represents a novel genus within the family Rhodobacteraceae. Metabolically, it possesses a wide array of amino acid metabolic genes that enable it to thrive on both amino acids or peptides. Also, it could hydrolyze peptides containing D-amino acids, highlighting its potential role in the cycling of refractory organic matter. Moreover, strain LCG007 could utilize various carbohydrates, including mannopine and D-apiose—compounds primarily derived from terrestrial plants—demonstrating its capacity to degrade terrestrial organic matter. It could assimilate ammonia, nitrate and nitrite, and utilizes organic nitrogen sources such as polyamines, along with diverse organic and inorganic phosphorus and sulfur sources. Importantly, unlike very limited Sulfitobacter species that possess photosynthetic genes, the genomes of strain LCG007-affiliated genus and all Roseobacter species harbor photosynthetic gene clusters. This conservation was further supported by the significant impact of light on the growth and cell aggregation of strain LCG007, suggesting that acquirement of photosynthetic genes could play a crucial role in the speciation of their common ancestor. In terms of environmental adaptability, the genes that encode for DNA photolyase, heat and cold shock proteins, and enzymes responsible for scavenging reactive oxygen species, along with those involved in the uptake and biosynthesis of osmoprotectants such as betaine, γ-aminobutyric acid (GABA), and trehalose collectively enable strain LCG007 to survive in the dynamic and complex intertidal zone environment. Besides, the capacity in biofilm formation is crucial for its survival under conditions of oligotrophy or high salinity. This study enhances our comprehension of the microbial taxonomy within the Roseobacter clade affiliated cluster, their survival strategies in intertidal ecosystems, and underscores the significance of their role in nutrient cycling. It also highlights the crucial importance of photosynthetic metabolism for the speciation of marine bacteria and their ecological resilience.

The intertidal zone, a dynamic interface of marine, atmospheric, and terrestrial ecosystems, exposes microorganisms to rapid shifts in temperature, salinity, and oxidative stress. Strain LCG004, representing a novel Palleronia species, was isolated from the Lu Chao Harbor’s intertidal seawater in the Western Pacific Ocean. The genome of the organism reveals its metabolic versatility, enabling the utilization of various organic substrates—ranging from organic acids, amino acids, to sugars, and encompassing complex carbohydrates—as well as adept handling of inorganic nutrients, thereby highlighting its significant role in the cycling of nutrients. The strain is equipped with multiple osmoprotectant transporters, deoxyribodipyrimidine photo-lyase, and a comprehensive antioxidant defense system, featuring with multiple catalases, peroxidases, and superoxide dismutases, enabling it to withstand ever-changing environmental conditions, UV radiation, and oxidative challenges. Notably, LCG004 exhibited enhanced growth and cell aggregation under oligotrophic conditions, promoted by light exposure, underscoring the significant influence of light on its morphological and physiological attributes. This study elucidates strain LCG004’s metabolic characteristics and ecological potential, and offers insights into its contributions to biogeochemical cycles and survival strategies in one of nature’s most fluctuating environments.

Salt marshes are being lost worldwide even though they provide essential ecosystem services. Habitat classification of salt marshes based on fauna, which is an effective indicator of their ecosystems, is expected to be useful to effectively assess the baseline for conservation and restoration; however, it has not been well studied. This study aimed to identify the diversity of salt marsh sub-habitats for fauna, where biota was collected and the physicochemical environments were measured in 101 small patches of salt marsh (i.e., survey sites) across 32 temperate tidal rivers and inlets in Fukuoka Prefecture, Kyushu, Japan. A total of 78 aquatic animal species (decapod crustaceans, gastropod mollusks, bivalves, nereidid polychaetes, and fish) were observed, 63 of which were used as indicators for sub-habitat identification. Although reed plants covered 90 of the 101 survey sites, the survey sites were classified into six clusters based on fauna. Representative aquatic animals were identified in each cluster, and these six clusters had different physicochemical environments, such as salinity and sediment conditions. The results indicated that the six sub-habitats had different biotic and abiotic characteristics. On the other hand, the results of the ordination analysis indicated that the fauna of the six sub-habitats do not occur independently of each other but are composed of continuous and gradually changing fauna along environmental gradients. Although no significant differences in the areas of salt marsh patches among the clusters, species richness differed significantly, suggesting that physicochemical environments, such as salinity and sediment conditions, rather than spatial factors, may affect species diversity. The findings emphasize that each sub-habitat supports species diversity in temperate salt marshes and are expected to contribute to planning targets for future salt marsh conservation/restoration and further improvements in artificial marshes.

Labakkang Beach, Pangkajene Islands Regency has the characteristics of gently sloping coastal waters covered with various mangrove and seagrass communities. In general, seagrass is more commonly found in intertidal than subtidal areas, this is due to the depth reason. However, based on first observations, seagrass in Labakkang coastal waters thrives in subtidal areas and is less fertile in intertidal areas. The purpose of this study was to decide the differences in species, cover, and density of seagrass in intertidal and subtidal areas in the waters of Labakkang Beach, Pangkajene Islands Regency. This research was conducted in July 2021 with the method used, namely purposive sampling. Measurements of environmental parameters at the sampling location were carried out directly (in situ) including temperature, salinity, tides, depth, and current velocity, while turbidity, Total Organic Matter (TOM) analysis, and grain size of sediment were carried out tegakanirectly (ex-situ). The results of the average measurements of temperature, salinity, current velocity, depth, turbidity and TOM respectively show the range of 300C - 310C; 33.3‰ – 35.0‰; 0.07 m/s - 0.18 m/s (at high tide); 0.31 m - 1.32 m; 11.06 NTU - 29.04 NTU and 2.49 % - 5.39 %. The results of sediment analysis using Software Gradistat are 2 types of sediment, namely medium sand & fine sand and 2 types of sediment texture, namely Slightly Gravelly Sand and Slightly Gravelly Muddy Sand. The average percentage of seagrass cover at the intertidal station was 23.33 % while at the subtidal station it was 61.11% and only 2 species of seagrass were found, namely Enhalus acoroides and Halophila ovalis. The average density of seagrass at the intertidal station is 48.88 ind/m2 while at the subtidal station it is 86 ind/m2. The results of the Independent T-test analysis showed that there were significant differences in the cover and density of seagrass in the intertidal zone and subtidal zone in the coastal waters of Labakkang.

For the management of estuaries and the preservation of tidal flats it is crucial to understand the tidal flat shape and development. Previous work focused predominantly on the quasi-equilibrium shape of tidal flats along open coasts with a dominant cross-shore flow and wave exposure. This paper evaluates the shape of fringing tidal flats in engineered estuaries, where longshore velocities generally dominate. Using a long-term (20 years) topographic data set of an anthropogenically modified estuary in the Netherlands (the Western Scheldt estuary), we relate key profile shape parameters and changes over time to natural and anthropogenic processes. In an engineered estuary, the tidal flat shape depends on the estuary geometry, hydrodynamic forcings and human interventions. In contrast to open coast tidal flats, the presence of the channel and dominant longshore flow determines the available cross-shore length (accommodation space) of the tidal flat and the shape of the tidal flat. This accommodation space defines the maximum tidal flat height and opportunity for marsh development. We propose the use of the Index of Development, indicating to what extend tidal flats have space to develop. This index is not only influenced by longshore and cross-shore flow, but also (or even more) by hydraulic structures, dike realignments and channel migration. Especially the latter two strongly influence the accommodation space and thereby the maximum tidal flat height and the opportunity for marsh development. For large stretches of the Western Scheldt, the accommodation space is too small, and the majority of the tidal flats do not vertically extent to mean high water. The success of tidal flat and marsh restoration projects depends on the accommodation space. [ABSTRACT FROM AUTHOR]

A new intertidal species of the melitid amphipod, Melita panda, from the Wakayama Prefecture, Japan, is identified and described. Melita panda sp. nov. differs from the similar M. koreana and M. nagatai by its black-and-white body color, well-developed anterodistal projection of the male gnathopod 1 propodus, and telson armature. Molecular phylogenetic analyses based on the nuclear 28S rRNA and mitochondrial COI genes support that M. panda sp. nov. is closely related to M. koreana and M. nagatai. [ABSTRACT FROM AUTHOR]

Tylorrhynchus osawai, nereidid polychaete that is considered to support estuarine biodiversity, undergoes a unique epitokous metamorphosis for reproductive swarming. The reproductive swarming of this species has been observed in Japan for more than 100 years; however, the benthic phase of this species has not been well researched. In this study, we aimed to elucidate the morphological allometry and life history, specifically the reproductive swarming, of this species. To accomplish this, surveys were conducted to collect atokes and epitokes from a tidal river in Kyushu, Japan. A total of 1670 T. osawai specimens were collected and preserved in 80% ethanol. The body widths of these specimens were measured, while several intact specimens underwent additional measurements of body length and the number of chaetigers. The morphological allometry of this species differed between atokous and epitokous forms, indicating that its heteronereis form might be suitable for migration from a tidal river to the ocean. The survey results pertaining to the benthic phase of this species indicated that its lifespan was approximately one year or longer. In addition, the settlement, growth, and maturity of this species exhibited a degree of plasticity, potentially influenced by habitat landscapes and sediment conditions. Based on the surveys conducted on reproductive swarming, climate change could have caused the peak of reproductive swarming to shift slightly later than that of several historical observations. Our findings contribute to elucidating the ecological significance of epitokous metamorphosis in nereidid polychaetes and to conserving T. osawai populations. [ABSTRACT FROM AUTHOR]

En las últimas décadas, se viene registrando en el Atlántico noreste un cada vez mayor número de citas de especies ictiológicas de aguas cálidas más meridionales. Diversos trabajos relacionan este fenómeno con el aumento de la temperatura de las costas europeas como consecuencia del calentamiento global. En este contexto, se documenta para el mar Cantábrico la primera cita de un ejemplar de góbido del género Zebrus de distribución principalmente mediterránea y con tan solo unas pocas citas en el océano Atlántico. ABSTRACT: In recent decades, an increasing number of records of ichthyological species from more southern warm waters have been recorded in the northeast Atlantic. Several studies relate this phenomenon to the increase in the temperature of European coasts as a consequence of global warming. In this context, here we document the first record for the Cantabrian sea of a specimen of a gobid fish belonging to Zebrus genus, which typically exhibit a Mediterranean distribution with only a few records in the Atlantic Ocean.

To understand the seasonal variations in shellfish community structure, the composition and diversity of shellfish in the intertidal zone of the Changshan Archipelago, China, were investigated. We investigated the composition and diversity of shellfish species in the intertidal zone (including NCD1, NCD2, BCD1, BCD2, TJD1, TJD2, DQD1, DQD2, NHD1, and NHD2) of five representative islands and 10 survey stations in the Changshan Archipelago during the low tide period in July and October 2021 and February and May 2022, and the water quality parameters of point water and interstitial water were analyzed. The results showed that the bottom material of the Changshan Archipelago was generally rock or gravel and the salinity fluctuated with the seasons. The salinity was high in summer and fall while low in spring and winter, with an average of 30.92±0.84. Compared with spring, summer, and fall, the temperature changed significantly in winter, with an average of (4.51±0.32) ℃ and the highest temperature being 23.48 ℃ during spring, summer, and fall. In general, the dissolved oxygen in the main islands of Changshan Archipelago (North and South Changshan Islands) was relatively low, with an average of (8.59±0.38) mg/L, while that in Tuoji Island, Daqin Island, and Nanhuangcheng Island was relatively high, with an average of (9.95±0.51) mg/L. A total of 12 species of shellfish were collected in this survey, including Crassostrea sp., Monodonta labio Linnaeus, Littorina brevicula, Mytilus galloprovincialis, Patelloida pygmaea, Chlorostoma rustica, Reishia clavigera, Thais luteostoma, Ocinebrellus inornata, Cellana toreuma, Ruditapes philippinarum, and Rapana venosa. The number of shellfish species in each season was the highest in spring, with an average of eight species, followed by in fall, with an average of six species. Winter had the least number of shellfish species collected, with an average of four species. In addition, the North and South Changshan Islands presented the most shellfish species at eight and nine species, respectively. The number of shellfish collected in DQD was the least (six species). There were differences in shellfish density at different survey sites, among which DQD2 had the highest density, with an average density of 41.26 ind./m2. The lowest density was in NCD2, and the average density was 13.71 ind./m2. In the same season, the shellfish density at different survey sites was different, the proportion of dominant species at different survey sites was also different. In spring, the density of Crassostrea sp., Cellana toreuma, and Chlorostoma rustica was high, while in summer, the density of Crassostrea sp., Mytilus galloprovincialis, Littorina brevicula, and Cellana toreuma was high. In fall, the density of Crassostrea sp., Littorina brevicula, and Mytilus galloprovincialis was the highest, while in winter, the density of Crassostrea sp., Patelloida pygmaea, and Cellana toreuma was the highest. The species diversity (H´) of shellfish in each tidal area of the survey site is shown as middle tidal zone (1.44) > low tidal zone (1.40) > high tidal zone (0.44). Overall, the average shellfish species diversity in the 10 survey sites was spring (1.26) > winter (1.21) > fall (1.11) > summer (0.95). The average evenness index of species (J´) in the 10 survey stations was 0.55, among which the evenness index of DQD2, NCD2, NHD2, and TJD1 shellfish was 0.67, 0.64, 0.64, and 0.55, respectively. The evenness index of shellfish in each tidal area of the survey site was in order of middle tidal zone (0.67) > low tidal zone (0.59) > high tidal zone (0.29). The seasonal change was not obvious. The average shellfish abundance at the survey site was 0.533, including 0.82, 0.68, 0.60, and 0.53 shellfish abundance at NCD2, NHD2, BCD2, and NCD1, respectively. The abundance index of shellfish in each tidal area of the survey site was in order of middle tidal zone (0.56) > low tidal zone (0.52) > high tidal zone (0.17). Overall, the average shellfish abundance in the 10 survey sites was spring (0.681) > fall (0.573) > summer (0.458) > winter (0.418). Seasons (temperatures) have the most obvious impact on the diversity and abundance of intertidal shellfish resources. Anthropogenic activities, such as aquaculture and tourism, also affect the distribution and quantity of shellfish species. The results of this study not only enrich the data of intertidal shellfish resources on islands in China but also provide basic information and reference for biodiversity and environmental protection of intertidal shellfish on the Changshan Islands.

Based on the existing deep soft soil geological conditions in beach area, greater challenges were brought to the construction of cast-in-place box girders. Relying on the first phase project of Shiyitang Expressway in Zhejiang Province, the influence of artificially solidified hard shell layer on bridge pile foundation under preloading load was studied. Based on the soil hardening model, a three-dimensional numerical calculation model was established. The variation law of axial force, lateral friction resistance and horizontal displacement of pile body under different depth of hard shell was compared. The results show that when the thickness of the hard shell is 2 m, the axial force of the pile is reduced by about 16% . The thickness of the hard shell layer will change the transfer depth of the negative friction resistance, which shows that the thicker the thickness of the hard shell layer, the more the neutral point of the pile side resistance moves up. In addition, in a certain depth influence range, the hard shell layer can effectively control the horizontal displacement of the pile top and the pile body at different depths. The larger the thickness of the hard shell layer, the smaller the horizontal displacement of the pile top. Finally, the influence of soil modulus on the horizontal displacement of the pile was analyzed. It is found that the horizontal displacement of the pile will decrease with the increase of the compression modulus of the soil, and the influence of soil unloading / reloading stiffness modulus Eur is higher than that of soil deflection loading stiffness modulus E50 and lateral compression stiffness modulus of soil Eeod . [ABSTRACT FROM AUTHOR]

Knowledge of fish movement ecology contributes to the improvement of fishery resource management actions. We investigated the horizontal movement of the black sea bream Acanthopagrus schlegelii around the natural coast of Nishinoumishima Island in Hiroshima Bay, using active acoustic tracking. Six adult fish equipped with depth transmitters were tracked for a total of 54 days in the bay. Five tagged fish were fully tracked for 9–10 consecutive days after release. Tagged fish were found in the intertidal zone and adjacent subtidal zones, which were shallower than 12 m, and within 170 m off the coastline. The mean daily movement distance and 95% kernel utilized density of tagged fish were 191 ± 272 m and 60,207 ± 99,437 m2, respectively. The swimming depth of the tagged fish was 1–4 m above the seafloor. We opine that the littoral area (< 12 m in depth), which includes the intertidal zone and adjacent subtidal zone, is an important habitat for black sea bream. [ABSTRACT FROM AUTHOR]

The research progress of benthic diatoms on sandy beach at home and abroad was reviewed in this paper. As the main flora of sandy beach, benthic diatoms adapted to the changeable sandy environment through a series of mechanisms. In the sediments of the intertidal zone, benthic diatoms were an important part of primary productivity and beach food webs. Sediment, temperature, salinity, light, nutrients and biological factors all affected the growth and community distribution of benthic diatoms. In recent years, there had been studies on the distribution characteristics of benthic diatom communities in the intertidal zone of China, but generally speaking, there were relatively few studies on benthic diatoms in sandy environment, and further investigation is needed to improve the study of diatom ecology in China. [ABSTRACT FROM AUTHOR]

The presence of microplastics in tidal sediments is a growing ecotoxicological concern for sea and benthic health. This investigation was designed to record and characterize the vertical prevalence of microplastics (MPs) in intertidal sediments of the Persian Gulf (around Bushehr city, Iran). Sediments of three depths (0-10 cm, 10-20 cm, and 20-30 cm) were sampled during low tide in six sites along the coastal zone of Bushehr, Iran. MP particles were found in all evaluated areas and sediment depths. The average abundance of MPs in all of the sediment samples was 117.96 ± 97.75 particles kg−1 dry sediment. No differences were found in the MPs number among the sites. The most dominant microplastics in surface sediments were 2-5 mm in size. In all areas, fibers and fragments were more abundant. Particles in higher depths (0-10 cm) were often colorless (white, and transparent). Raman spectroscopy indicated the presence of polystyrene, polyethylene, polyvinyl chloride, polyethylene terephthalate, and polypropylene in the samples. Further research is required to evaluate the possible interaction between MPs and layers of sediments. Waste management and proper wastewater disposal are critical to control MPs pollution in intertidal ecosystems around coastal cities.

For the management of estuaries and the preservation of tidal flats it is crucial to understand the tidal flat shape and development. Previous work focused predominantly on the quasi-equilibrium shape of tidal flats along open coasts with a dominant cross-shore flow and wave exposure. This paper evaluates the shape of fringing tidal flats in engineered estuaries, where longshore velocities generally dominate. Using a long-term (20 years) topographic data set of an anthropogenically modified estuary in the Netherlands (the Western Scheldt estuary), we relate key profile shape parameters and changes over time to natural and anthropogenic processes. In an engineered estuary, the tidal flat shape depends on the estuary geometry, hydrodynamic forcings and human interventions. In contrast to open coast tidal flats, the presence of the channel and dominant longshore flow determines the available cross-shore length (accommodation space) of the tidal flat and the shape of the tidal flat. This accommodation space defines the maximum tidal flat height and opportunity for marsh development. We propose the use of the Index of Development, indicating to what extend tidal flats have space to develop. This index is not only influenced by longshore and cross-shore flow, but also (or even more) by hydraulic structures, dike realignments and channel migration. Especially the latter two strongly influence the accommodation space and thereby the maximum tidal flat height and the opportunity for marsh development. For large stretches of the Western Scheldt, the accommodation space is too small, and the majority of the tidal flats do not vertically extent to mean high water. The success of tidal flat and marsh restoration projects depends on the accommodation space.

Based on the survey data in July 2020, the paper investigated the distribution characteristics and species diversity of the intertidal macrobenthic community in the Shankou Mangrove Reserve. A total of 52 species of macrobenthic animals in 7 phyla and 9 orders were recorded in this survey, mainly arthropods and mollusks. Chasmagnathus convexus, Paracleistostoma depressum, Gelonia coaxans, etc. were ranked as the top ten dominant species in the area. The average biomass and average density of macrobenthos were 81.17 g/m2 and 54 ind/m2, with Arthropods accounting for 43.70% and 80.09% of the total. Arthropods contributed the most to the community density. The diversity index of the macrobenthic community ranged from 0.86 to 2.52. Cluster analysis and multidimensional scale analysis could classify the communities into 3 types. Species diversity levels of the intertidal macrobenthic community in the Shankou Mangrove Reserve were low compared with other mangrove areas in China.

With the growing global focus on marine environmental conservation and management, it is imperative to evaluate the ecological quality of marine ecosystems accurately. In this study, we employed seven biotic indices, namely the AZTI marine biotic index (AMBI), BENTIX, benthic opportunistic polychaetes amphipods index (BOPA), benthic pollution index (BPI), multivariate AZTI marine biotic index (M-AMBI), abundance biomass comparison (W-value), and Shannon diversity index (H'), to assess the benthic ecological quality in the intertidal zone of Cheonsu Bay, South Korea. Except for the H' and W-value, the indices (AMBI, BENTIX, BOPA, BPI, and M-AMBI) suggest that the ecological quality at most stations in the intertidal zone of Cheonsu Bay was acceptable. Furthermore, the influx of a large amount of eutrophic freshwater has impacted the intertidal zone of Cheonsu Bay, but the applicability of the seven biotic indices requires further investigation. [ABSTRACT FROM AUTHOR]

Spatial changes in environmental characteristics strongly influence the structure of benthic communities on sandy beaches, where the patterns of occurrence are mainly controlled by morphodynamic characters and biological interactions. Despite being very abundant and extensive, the Amazonian sandy beaches are among the coastal environments less well known to science. On these beaches, the ghost shrimp Lepidophthalmus siriboia Felder and Rodrigues, 1993 is an important component of the intertidal macrofauna. The present study describes the small-scale distribution patterns of L. siriboia and of the macrobenthic communities in a dissipative macrotidal Amazonian sandy beach. Samples were collected in the intertidal zone of two areas: Area 1, next to a tidal channel; and Area 2, away from the tidal channel. In Area 1, with finer sediments, there was a higher burrow density of L. siriboia and higher density and species richness of macrofauna. In both areas, the burrow density of L. siriboia increased towards the sea. The faunal distribution patterns can be explained by changes in flooding and the type of substratum across the shore and alongshore. These findings add to our knowledge of tropical sandy beach ecology and reinforce the idea that tropical macrotidal beaches have a complexity of morphological features, which are drivers of macrofaunal structure. [ABSTRACT FROM AUTHOR]

Marine worms of the family Serpulidae (Annelida) construct calcareous tubes that adhere to hard substrata. The tubes of the Spirobranchus kraussii complex have a flat projection, known as a 'flap', over the opening of the tube. In the present study, we examined the reconstruction growth rates of the flap of Spirobranchus akitsushima after artificial removal, compared with the normal growth rates (control), for approximately a month at a study site in Shirahama, Wakayama, Japan. Although the difference in the length of the flap on day 8 compared with the original length (before the removal treatment) was significant in the treatment group, the differences became nonsignificant after day 13. The flap growth rate was found to be higher than the growth rates of the tubes of other serpulid species, including Spirobranchus sp. 5 sensu Kobayashi & Goto (2021) of the S. kraussii complex, as reported in previous studies. In contrast, the length of the flap in the control group did not differ significantly during the survey period. These results indicate that the flap is more quickly reconstructed after removal compared with growth under normal conditions. Our findings imply that the flap may be of importance for the survival of S. akitsushima. [ABSTRACT FROM AUTHOR]

The population structure and somatic condition of intertidal gastropods can be affected by the degree of exposure to waves on rocky coasts. We studied the influence of wave exposure and climatic temporality on the sizes and somatic condition of two species of intertidal neogastropods (Plicopurpura patula and Vasula deltoidea), at different sites within the coastal strip of Santa Marta, Colombian Caribbean. The study was conducted in two areas, Santa Marta Bay and Tayrona National Natural Park, where four collection stations were established. The study was carried out from 2015 to 2017 with eight sampling campaigns. Shell size, weight, biofouling proportion, condition index, and wave exposure index were determined. Only in P. patula was there a direct and significant relationship between the level of exposure to waves and sizes (p = 0.011, r2 = 0.683). Significant variation in the condition index occurred in V. deltoidea when specimens collected from the upper intertidal exceeded the values of those extracted from the supratidal up to two meters depth. Wave exposure affects the species P. patula, which is found in the supralittoral zones, presenting larger sizes in the sites with greater wave exposure. [ABSTRACT FROM AUTHOR]

Illustrated descriptions and differential diagnoses of four new species of psammophilous microturbellaria from the genera Coulterella Timoshkin 2004, Cohenella Timoshkin 2004, and Linella Timoshkin 2004 (Kalyptorhynchia, Rhynchokarlingiidae) inhabiting the intertidal zone of Lake Baikal are provided. Short notes on their ecology and distribution are presented. All species have been found in sandy soil at a depth of 1.5–3 m and represent a part of the psammophilic communities of the lake. [ABSTRACT FROM AUTHOR]

Information concerning the allometric growth of the bivalve mollusk (Mya arenaria) populations in the intertidal zones of Zelenetskaya and Yarnyshnaya inlets, Barents Sea, is presented. The population density in Zelenetskaya Inlet averages 40 ind./m2 and the biomass is 280 g/m2 versus 62.6 ind./m2 and 142 g/m2 in Yarnyshnaya Inlet, respectively. A detailed analysis of the granulometric composition of bottom sediments of the intertidal zone and the content of organic matter are determined for the first time. The study areas are found to differ in the composition of bottom sediments. The organic matter in Zelenetskaya Inlet averages 0.8% versus 2.2% in Yarnyshnaya Inlet. Shell formation is determined by adaptations to living conditions, also reflecting the different size and age structure of M. arenaria populations. Among the mollusks of older age groups, the shell grows allometrically, following the principle of weak negative allometry versus isometrically among young individuals. [ABSTRACT FROM AUTHOR]

A commercial fishery for the Cape rock oyster Striostrea margaritacea along the north coast of KwaZulu-Natal, South Africa (western Indian Ocean), follows a 4-year rotational cycle, with each harvest year followed by 3 fallow years across four harvest zones. We analysed reported harvesting effort and catch information, and fishery-independent oyster size composition data collected over 18 years (Feb 2003-Feb 2020), to investigate the sustainability of rotational harvesting. Total harvesting effort and catches declined over the study period, but on average, the number of oysters collected per outing increased. Fewer outings in recent years were attributed to incomplete reporting and a progressive loss of access to harvest sites. Generalised linear mixed models were used to estimate trends in oyster mean size in relation to fishing method (divers and intertidal collectors), harvest zone, 4-year rotational cycles, and months spent in a zone. Oyster mean size increased from north to south along the coast. Oysters caught by divers on newly exploited deeper reefs were initially larger than those caught by intertidal collectors. Mean oyster size decreased monthly during 1-year harvest periods but recovered to pre-harvest size over 3 fallow years. The results confirmed that the current rotational harvest strategy is well-suited to oyster biology and is sustainable at the present level of effort. Improved reporting on harvesting effort and catch are required to verify longer-term spatiotemporal trends in this fishery. More effective stakeholder communication is needed to resolve potential user conflict [ABSTRACT FROM AUTHOR]