Subtidal Research Articles

Vulnerability of tidal morphologies to relative sea-level rise in the Venice Lagoon

The rise in sea level and land subsidence are seriously threatening the diversity of tidal morphologies that have made the Venice Lagoon such a distinctive landscape. Here, we assess the vulnerability of tidal morphologies to relative sea-level rise based on a new conceptual framework that accounts for both above- and below-sea-level zones, sedimentary architecture, and surface morphology. Around 80 % of the lagoon area will face moderate to severe vulnerability by 2050, doubling compared to the 1990s. While the subtidal zone may be relatively less threatened compared to past conditions, the drastic decline in intertidal morphologies is alarming. This contributes to the flattening and deepening of the lagoon topography and thus to the loss of lagoon landscape diversity, likely leading to a decrease in the ecosystem services the tidal morphologies provide. The interconnection of intertidal and subtidal morphologies is crucial for maintaining the overall health and functionality of the lagoon's ecosystem. Any disruption to one aspect can have ripple effects throughout the entire system.

Local and global stressors as major drivers of the drastic regression of brown macroalgae forests in an oceanic island

Similar to other coastal regions worldwide, forests created by brown macroalgae have severely declined in recent decades across the Macaronesian oceanic archipelagos (northeastern Atlantic), eroding the provision of ecosystem services. However, the putative effects of natural and anthropogenic stressors (both local and global) on such declines across spatial and temporal scales remain unresolved. Our research endeavored to investigate the connection between local and global stressors and the distribution and extent of the brown macroalgae Gongolaria abies-marina in the rocky intertidal and adjacent subtidal zones of Gran Canaria over the past four decades. We also quantified the presence of populations at small scales, according to local micro-habitat topography (“open rock” versus “refuge”). Through herbarium records, we additionally analyzed the historical variation in the thallus size of the species. Finally, we experimentally assessed the thermotolerance of embryonic stages to warming. The main environmental drivers explaining the regression of G.abies-marina were the increasing number of marine heatwaves, while the number of local human impacts (quantified through the HAPI index) also accounted for further regression in the extent of marine forests. Warming experimentally reduced the survival and size of macroalgal embryos. A progressive miniaturization of the species, currently restricted to micro-habitat refuges as a survival strategy, seems likely to be the final stage in the progressive disappearance of this macroalgae from the island’s rocky shores.

Does the incorporation of shell waste from aquaculture in the construction of marine facilities affect the structure of the marine sessile community?

The growth of the human population causes significant harm to ecosystems, directly affecting the biological diversity of coastal areas by replacing natural habitats with artificial structures such as breakwaters, ports, and marinas. The hard substrate from those marine facilities lacks the topographic complexity of natural habitats. Because of that, artificial habitats usually do not support a diverse community to the same extent as rocky shores in the surroundings. To address this issue and bring a strategic solution to the improper disposal of shell waste from aquaculture farms, we evaluated how increasing the environmental heterogeneity of walls by incorporating mussel and oyster shells on artificial concrete affected the diversity of sessile organisms from the subtidal zone. Adding shells to concrete positively affected ascidians' richness. Substrates with added shells supported more species than flat substrates in total. They promoted species that did not occur on flat substrates that simulated the traditional walls of marinas and harbors. However, it did not affect the number of bryozoans and the average species richness. Consequently, incorporating shells resulted in communities with completely distinct structures from those on flat substrates. Adding shells affected the community structure, reducing the dominance by the exotic bryozoan Schizoporella errata, and promoting the occurrence of other groups, such as ascidians. Using shell residues from aquaculture on marina walls adds substrate for colonization. Still, it is also likely to provide refuges for fragile and vulnerable organisms, like crevices and pits in natural habitats. Because of that, the increment in diversity was mostly group-specific and restricted to ascidians. This research reinforces the importance of creating complex artificial coastal structures, inspired by the blue economy, for a more heterogeneous coverage of sessile communities and reduced presence and dominance of exotic species. Thus, the strategy tested here, besides the effects on the sessile community, also supports efforts to reduce inappropriate waste disposal in the environment.

Marsh boundary degradation into open-water in living shorelines under high-energy conditions

Living shorelines have been recognized for their potential to attenuate wave energy, reduce shoreline erosion, and enhance coastal resilience, and are gaining traction as a preferred method of shoreline stabilization. Yet much remains uncertain about their resiliency and effectiveness in reducing shoreline erosion during high-energy events. This study examines sediment dynamics at a relatively mature living shoreline (constructed in 2007 and comprised of a created marsh and rock sill at the land/water interface) in the Maryland Coastal Bays (USA) during a storm event via field surveys and numerical modeling. Results are evaluated within the context of observations at an adjacent natural marsh. Our study demonstrates that the mechanisms of marsh loss at the edge during these times differ between the living shoreline and natural marsh. Specifically, the living shoreline boundary is degraded through open-water conversion as ponds expand landward of the rock sills, but the natural marsh is eroded by undercutting at the scarp toe, triggering slumping and edge collapse. Sediments in the living shoreline marsh have larger particle sizes and lower organic content than in the natural marsh; vegetation has higher stem heights and lower stem densities compared to the natural marsh. These differences may drive differences in the stability of the marsh boundary. Numerical modeling indicates that bed shear stresses are higher landward of the rock sill at the edge of the vegetation in the living shoreline. This increase in shear stress under high-energy conditions occurs at both flood and ebb tide, potentially contributing to scouring and/or open-water conversion, as well as substantial sediment transport between the subtidal zone and the marsh platform of the living shoreline. Increasing the bank height (both sill and marsh) may reduce erosion at the marsh edge and/or prevent open-water conversion but should be carefully balanced with marsh ecology and processes during other times of the year.

Characteristics and paleoenvironmental conditions of the well-preserved Early Mesoproterozoic Fengjiawan Formation stromatolites in the southern North China Craton

Stromatolites in the lower part of the Early Mesoproterozoic Fengjiawan Formation in the southern North China Craton (NCC) contain abundant microbial dolostones with well-preserved primary structures. This study comprehensively investigates the macromorphological, petrographical, mineralogical, and geochemical characteristics of these pure stromatolite-dominated microbialites for the first time. The results reveal diverse macromorphological structures distributed from the bottom to the top as conical (lower intertidal to upper subtidal zones), hemispherical domal (lower supratidal zone), spherical domal (upper to middle intertidal zone), and more abundant columnar (upper to middle subtidal zone) stromatolites. The mineral composition of these stromatolites indicates that they are pure dolostones, predominantly consisting of dolomite (avg. 94.24 wt%). These stromatolite-dominated microbialites were subjected to minimal detrital contamination and weak post-depositional alteration as documented by different geochemical multiproxy evaluations. This indicates that they have effectively retained the composition of the seawater in which they were initially formed. Geochemical indicators, such as Y/Ho, La/La*, Gd/Gd* and Ce/Ce* strongly suggest deposition of the stromatolites in an open shallow marine environment characterized by a passive continental margin setting. Different elemental ratios, such as Ce/Ce*, MoEF, UEF, MoEF/UEF, imply the stromatolites formation under a suboxic redox environment, where the photosynthesis of cyanobacteria likely played a significant role in the slight oxygenation of the seawater during their formation. These oxygenation levels decreased as water depth increased, with more nutrient supply promoting from deeper waters. The formation and growth of the stromatolite-dominated microbialites were significantly influenced by various depositional conditions, including sea level fluctuations, biological processes, suboxic redox environment, low detritus contamination, and weak post-depositional alteration. These conditions all contributed to the excellent preservation of the Fengjiawan Formation stromatolites, providing valuable insights into deep time microbial carbonates.

First data on the diet of Razorbill Alca torda wintering in the Mediterranean Sea: insights from social media

Understanding a species’ diet is of paramount importance to ecology as it provides vital insights into interactions between organisms and their environment. In this study, we report the first data on the diet of wintering Razorbills (Alca torda) in the Mediterranean Sea. Taking advantage of the irruption event that occurred in the Mediterranean in winter 2022/2023, a data mining search campaign was carried out on social media to collect photographs and videos documenting Razorbills feeding at sea. Additional information was gathered by analysing the stomach contents of dead individuals salvaged from the coastline of central Italy. Overall, we obtained records from 32 pictures and 7 videos as well as 7 dead individuals. All prey items belonged to class Actinopterygii. Overall, 12 fish prey were identified (2 at the family, 3 at the genus and 7 at the species level). Razorbills fed on small-medium sized fish species of the neritic zone such as Belone belone, Trachinotus ovatus, Atherina hepsetus and Engraulis encrasicolus. Razorbills were mostly observed foraging close to the coast and within harbours, as well as begging for food from humans, raising doubts about the feeding conditions encountered and the health status of individuals. Dead individuals mainly had empty stomachs, in line with the low weights and fat scores detected during necropsy. We underline how data from social media have made it possible to describe, using non destructive methods, the behaviour and feeding habits of an uncommon seabird typical of the North Atlantic Sea, which caught the attention of photographers, nature enthusiasts, and scientists.

Identification and simulation the response of storm-induced coastal erosion in the China Yellow sea

Storm events have a significant impact on coastal topography, which can subsequently lead to coastal erosion and ecological deterioration. Traditional field measurements are affected by environmental factors and consume substantial resources, making it difficult to conduct large-scale terrain, hydrodynamic and other monitoring tasks. Significant challenges still remain to identify the response of coastal processes to storm events due to the lack of field measured data. In this study, the response of coastal morphodynamical variations to extreme storm events was simulated by the coupled XBeach and FVCOM models and the storm-induced coastal evolution was evaluated in the China Yellow Sea. The costal morphodynamical variations under different wind conditions were also quantified. The results reveal that erosion dominated the supratidal zone while accretion mainly occurred in the subtidal zone. Comparing the coastal morphology before and after the storm, we found the alongshore currents were the primary factors influencing sediment transport. The degree of coastal erosion and accretion shift was positively correlated with the wind speed and direction. The present nested model may serve as a valuable tool for predicting future coastal erosion and accretion, contributing to more scientifically informed coastal management decisions. The study also provides a scientific basis for understanding the response mechanism of coastal morphodynamical process to extreme storm events and coastline evolution under global change.

Quantifying the δ15N trophic offset in a cold-water scleractinian coral (CWC): implications for the CWC diet and coral δ15N as a marine N cycle proxy

Abstract. The nitrogen (N) isotope composition (δ15N) of cold-water corals is a promising proxy for reconstructing past ocean N cycling, as a strong correlation was found between the δ15N of the organic nitrogen preserved in coral skeletons and the δ15N of particulate organic matter exported from the surface ocean. However, a large offset of 8 ‰–9 ‰ between the δ15N recorded by the coral and that of exported particulate organic matter remains unexplained. The 8 ‰–9 ‰ offset may signal a higher trophic level of coral dietary sources, an unusually large trophic isotope effect or a biosynthetic δ15N offset between the coral's soft tissue and skeletal organic matter, or some combinations of these factors. To understand the origin of the offset and further validate the proxy, we investigated the trophic ecology of the asymbiotic scleractinian cold-water coral Balanophyllia elegans, both in a laboratory setting and in its natural habitat. A long-term incubation experiment of B. elegans fed on an isotopically controlled diet yielded a canonical trophic isotope effect of 3.0 ± 0.1 ‰ between coral soft tissue and the Artemia prey. The trophic isotope effect was not detectably influenced by sustained food limitation. A long N turnover of coral soft tissue, expressed as an e-folding time, of 291 ± 15 d in the well-fed incubations indicates that coral skeleton δ15N is not likely to track subannual (e.g., seasonal) variability in diet δ15N. Specimens of B. elegans from the subtidal zone near San Juan Channel (WA, USA) revealed a modest difference of 1.2 ± 0.6 ‰ between soft tissue and skeletal δ15N. The δ15N of the coral soft tissue was 12.0 ± 0.6 ‰, which was ∼6 ‰ higher than that of suspended organic material that was comprised dominantly of phytoplankton – suggesting that phytoplankton is not the primary component of B. elegans' diet. An analysis of size-fractionated net tow material suggests that B. elegans fed predominantly on a size class of zooplankton ≥500 µm, implicating a two-level trophic transfer between phytoplankton material and coral tissue. These results point to a feeding strategy that may result in an influence of the regional food web structure on the cold-water coral δ15N. This factor should be taken into consideration when applying the proxy to paleo-oceanographic studies of ocean N cycling.

Comparison of macrozoobenthic communities and environmental variables in the subtidal zones between a nearly closed bay and an open bay

To compare the impact of human activities and geographical environment on macrozoobenthic communities in bays, four season surveys of macrozoobenthos and environmental variables in Kaozhou Bay (a nearly closed bay) and Honghai Bay (an open bay) were conducted. CLUSTER, non-metric multi-dimensional scaling (NMDS) and the relative importance index (IRI) showed that the macrozoobenthic communities were different between Kaozhou Bay and Honghai Bay. The top three dominant species in Kaozhou Bay are brackish species, including Dendronereis pinnaticirris, Euclymene annandalei and Neanthes glandicincta, while the top three dominant species in Honghai Bay are hyperhaline species, including Paraprionospio pinnata, Amphioplus laevis and Aglaophamus dibranchis. Two-way Analysis of Variance (ANOVA) showed that the species number, Shannon-Wiener diversity index, evenness index, richness index, AMBI, M-AMBI, water depth, salinity, and dissolved oxygen in Kaozhou Bay were significantly lower than those in Honghai Bay, while the concentrations of total nitrogen, total phosphorus, silicate, and mercury in Kaozhou Bay were significantly higher than those in Honghai Bay. Principal components analysis (PCA) showed that Kaozhou Bay was associated with higher concentration of total nitrogen, total phosphorus, and silicate, and Honghai Bay was characterized by deeper water, higher salinity, and higher concentration of dissolved oxygen. BIO-ENV analysis showed that water depth was the most important environmental factor affecting macrozoobenthic community in two bays. The above results showed that the species diversity index and richness index of Kaozhou Bay were lower than those of Honghai Bay because of the geographical environment difference between the two bays.

Discovery of modern living intertidal stromatolites on Sheybarah Island, Red Sea, Saudi Arabia

Abstract Microbial carbonates, and stromatolites in particular, represent the earliest geological record of life on Earth, which dominated the planet as the sole biotic carbonate factory for almost 3 b.y., from the Archean to the late Proterozoic. Rare and sparsely scattered across the globe in the present day, modern “living” stromatolites are typically relegated to extreme environmental niches, remaining as vestiges of a prodigious microbial past. Here, we report the first discovery of living shallow-marine stromatolites in the Middle East, on Sheybarah Island, Al Wajh carbonate platform, on the NE Red Sea shelf (Saudi Arabia). We detail their regional distribution and describe their environmental conditions, internal structures, and microbial diversity. We also report the first discovery of reticulated filaments in a photic setting, associated with these stromatolites. The Sheybarah stromatolites occur in the intertidal to shallow subtidal zones along the seaward-facing beach in three depth-dependent growth forms. Their inner layers were formed by microbially mediated accretion and differential lithification of sediment grains. Compositional microbial analysis revealed the presence of a wide range of microbial life forms.

Diversity of Echinoderms in the Subtidal Zone of Sintok Island, Karimunjawa National Park, Jepara, Indonesia

Aims: To determine the diversity of Echinoderms in the subtidal zone of Sintok Island.
 Study Design: This study applied a purposive sampling method.
 Place and Duration of Study: Sintok Island, Jepara, Indonesia, November 2019.
 Methodology: The belt transect method was used. The transect was drawn 200 m perpendicular from the coastline to the sea. The echinoderms in the 2m area along the transect line are observed for their diversity, the number of individuals from each species is counted, and the substrate is observed.The diversity index of Shannon-Wiener, evenness (uniformity), and dominance indices were analyzed.
 Results: The results showed 11 species belonging to 3 classes of Echinoderms found in Sintok Island. Holothuroidea class consisted of Holothuria atra, H. coluber, H. edulis, H. impatiens, Pearsonothuria graeffei, and Synapta maculata. Asteroidea class consisted of Culcita novaeguineae, Linckia laevigata, and Protoreaster nodosus. The Echinoidea class consists of Diadema setosum and Laganum laganum. H. atra was the most abundant species (0.70 ind.m-2). The diversity index value (H') of Echinoderm was in the range of 1.21 to 2.01, classified as a moderate condition.
 Conclusion: The echinoderm species in subtidal areas on Sintok Island could be a good tourist attraction in this national park.

Sediment quality classification in freshwater lakes predicted by the history of treatment with copper-based aquatic algaecides.

Copper-based aquatic algaecides have been widely used in the management of aquatic macrophyte and harmful algal blooms for decades due to their effectiveness and low cost. However, repeated treatment of freshwater lakes results in the accumulation of copper in the sediment, which may adversely affect the ecosystem of the lakes through toxicity to benthic invertebrates and other organisms. Consequently, copper-based aquatic herbicides and algaecides have been frequently subjected to regulations aimed at preventing further ecological deterioration in treated waterbodies. Many states in the US are taking or considering taking an approach that limits or prohibits copper treatment in waterbodies. Freshwater lakes with extensive historical copper treatments typically have significantly higher concentrations of copper in the sediment than untreated lakes. However, the correlation between the extent of the treatments and level of copper accumulation in the sediment has not been quantitatively characterized. In the present study, between 2006 and 2017, copper concentrations were measured in the sediment from selected lakes in New York State with different histories of copper-based aquatic algaecide treatment. Analysis of these data confirmed findings from earlier studies conducted by New York State that lakes with histories of copper treatment have significantly higher copper concentrations in the sediment. It also demonstrated that sediment copper concentrations were significantly higher in the sublittoral zone than the littoral zone in treated lakes. Moreover, a positive correlation was detected between sediment copper concentrations and the total number of treatments with copper-based aquatic algaecide for both littoral and sublittoral zones (p-value = 7.94 × 10-8 and 3.1 × 10-13, respectively). This relationship can be used as a screening tool for regulatory agencies to identify lakes with sediment copper levels possibly higher than the toxicity threshold for aquatic life. Consequently, additional ecological risk assessment may be required before allowing future treatment with copper-based aquatic algaecides. Integr Environ Assess Manag 2024;20:1586-1597. © 2024 SETAC.

Change in the Rock Erosion Rate in the Upper Sublittoral Zone of the Murmansk Coast

Change in the Rock Erosion Rate in the Upper Sublittoral Zone of the Murmansk Coast

The research of submarine pipeline's collision impacted by anchor of shipsin neritic zone

The research of submarine pipeline's collision impacted by anchor of shipsin neritic zone

First record of a cylindrical Dipterocladia (Ceramiales, Delesseriaceae), D. cylindrica sp. nov., from Korea based on morphological and molecular analyses

Abstract We describe a new species, Dipterocladia cylindrica, found in the subtidal zone of the eastern and southern coasts of Korea. This species has cylindrical branches with numerous sub-dichotomously branching monosiphonous determinate branchlets without adventitious filaments, heavy cortication throughout the thallus, and alternating clockwise periaxial cell formation. The external features of the new species are closer to those of the genus Dasya than to those of Dipterocladia, which have flattened thalli with pairwise distichously arranged monosiphonous pseudolateral and polysiphonous determinate laterals. However, based on the combined results of plastid rbcL and mitochondrial COI–5P sequences, the molecular phylogenetic relationships clearly indicate that our specimens belong to the genus Dipterocladia. We also detected more meaningful morphological characters for delineating the genus within the subfamily Dasyoideae by comparing the morphology and phylogeny, but we could not find unique characters for each clade. Further studies based on reproductive morphology and molecular phylogeny for delimiting the generic boundaries are needed.

Variasi Spasial Kepadatan Cacing Kacang di Pantai Toronipa Sulawesi Tenggara

The density of peanut worms is concentrated in the subtidal zone and is closely related to the substrate where they live. This research aims to determine spatial variations in peanut worm density. This research was carried out at Toronipa Beach, Southeast Sulawesi from June 2020 to February 2021. Peanut worms were collected using a hand scoop to a depth of ±10 cm in a 10x10 m2 quadrat transect at each station. Data were analyzed using standard formulas and tested using Mann-Whitney and linear regression. The results showed that the highest density of peanut worms was found at station II with a mean value of 12±104 ind/10m2 which was significantly different from stations I and III with densities of 9±52 ind/10m2 and 7±124 ind/10m2 respectively. Five types of seagrass were identified, namely Cymodocea rotundata, Enhalus acoroides, Halodule uninervis, Halophila minor, and Thalassia hemprichii. The number of seagrass species found at stations I, II, and III were 1, 2, and 5, respectively. Peanut worm density was positively correlated with seagrass density with a coefficient of determination of 86.45%. Water quality tends to be the same at all stations, except that organic matter is higher than at stations I and II. The dominant fine sand fraction was found at stations I and III, while very coarse sand was dominantly found at station II. The density of peanut worms on Toronipa Beach is determined by a combination of seagrass density, high levels of organic matter, and the dominant texture of the coarse sand substrate.
 
 Keywords: peanut worm, spatial density, Sulawesi, water quality

A new morphotype description of Arbacia spatuligera Valenciennes, 1846 (Arbacioida, Echinoidea) and bathymetric range extension from mesophotic reefs of the central coast of Chile

Abstract The sea urchin Arbacia spatuligera is an echinoid distributed in the Southeastern Pacific Ocean from Peru to Chile. This species was previously reported from the subtidal zone with a bathymetric distribution up to 30 m depth. In this work, 128 individuals were found in four mesophotic reefs along the central coast off Chile using closed-circuit rebreathers in technical diving at higher depths than previously, ranging from 36 to 63 m in depth. A population exhibits unexpected morphological characters, requiring an emended diagnosis and description of a new morphotype for A. spatuligera. These morphological traits are further discussed as potential ecophenotypic adaptations.

Cephalopod paralarvae in a tropical Brazilian basin: distribution throughout oceanographic features and water masses

The composition and distribution of cephalopod paralarvae were investigated in the Campos Basin, a tropical area on the southeastern Brazilian continental margin with extensive oil exploration. Zooplankton hauls with a multi-mesh net system were conducted during two seasonal oceanographic cruises in 2009 along eight isobaths (25–3000 m) and vertical sampling in five water mass cores (1–2300 m depth). A total of 825 paralarvae belonging to 11 families and at least 16 genera were captured. The majority had a dorsal mantle length of less than 2.60 mm, with a mean of 1.50 mm. The rainy summer showed higher total densities and number of families compared to the drier winter. Most paralarvae were collected at Surface Water (1 m depth), only four at South Atlantic Central Water (250 m), and two at Antarctic Intermediate Water (800 m). Enoploteuthidae and Ommastrephidae were the most abundant families and were positively associated with temperature, with higher densities during the rainy summer. Loliginidae were collected exclusively in the neritic zone. In the oceanic zone, Cranchiidae, Onychoteuthidae Octopoteuthidae, and Tremoctopodidae were collected at 1 m depth, and Ancistrocheiridae and Thysanoteuthidae at 250 m depth. Density peaks of paralarvae occurred during the summer along the continental shelf break and slope, an area known for frequent upwelling driven by cyclonic meanders of the Brazil Current.

Biotic assemblages of gelatinous zooplankton in the Gulf of Mexico and adjacent waters: An evolutionary biogeographic approach.

Gelatinous zooplankton constitutes a polyphyletic group with a convergent evolutionary history and poorly known biogeographical patterns. In the Gulf of Mexico, a region with complex geological, hydrological, and biotic histories, the study of this group has been limited to taxonomical and ecological aspects. In this study, we implemented a track analysis to identify distributional patterns of gelatinous zooplankton in the Gulf of Mexico and adjacent waters based on a dataset of 6067 occurrence records corresponding to Hydrozoa, Scyphozoa, Cubozoa, Ctenophora, Chaetognatha, Thaliacea, and Appendicularia. Information was compiled from the Global Biodiversity Facility Information (GBIF) and Ocean Biodiversity Information System (OBIS) databases and peer-reviewed literature. Individual tracks were constructed by joining the minimum distance between the occurrence localities of each taxon using a minimum spanning tree algorithm. We identified generalized tracks using parsimony analysis of endemicity with progressive character elimination (PAE-PCE). The areas where different generalized tracks overlapped were considered to represent panbiogeographical nodes. Seven generalized tracks (two with nested patterns) and six panbiogeographical nodes were recognized, mainly in neritic zones. The distributional patterns of gelatinous zooplankton allowed us to identify four biogeographic areas, supporting previously proposed biogeographic schemes. Gelatinous zooplankton in the Gulf of Mexico showed a convergent spatial distribution that can be explained by vicariant and dispersal events. The historical biogeography of the gelatinous biotas of the Gulf of Mexico has been little studied compared to ecological approaches, and the lack of integrative studies considering historical patterns is evident. This type of research is fundamental to understanding the evolutionary history of natural resources from a spatial perspective, identifying sites of biodiversity and endemism, and establishing a biogeographic baseline of the region for further studies.

A new gorgonian Pseudopterogorgiananjiensis sp. nov. (Cnidaria, Octocorallia, Gorgoniidae) from the Nanji Islands, China.

Members of the genus Pseudopterogorgia Kükenthal, 1919 are widely distributed in shallow water of the Indo-West Pacific. During an investigation of benthic biodiversity in the subtidal zone surrounding the Nanji Islands in the East China Sea, two specimens of Pseudopterogorgia were collected and described as a new species based on an integrated morphological-molecular approach. Pseudopterogorgiananjiensis sp. nov. is most similar to P.fredericki Williams & Vennam, 2001 in the irregular branching form and indistinct scaphoids, but differs by the coenenchymal sclerite content of distinct capstans and a few warty spindles and radiates (vs. mostly warty spindles and a few capstans), and a purplish colony (vs. white, pink to deep rose). Molecular phylogenetic analyses, based on the mtMutS-COI gene sequences, delineated a monophyletic clade encompassing all assessed Pseudopterogorgia species. Within this clade, P.nanjiensis sp. nov. showed a close phylogenetic affinity with both P.fredericki and P.australiensis Ridley, 1884.