Natural Mangrove Research Articles

Exotic mangrove Laguncularia racemosa litter input accelerates nutrient cycling in mangrove ecosystems.

Exotic plant litter presents different chemical and physical properties relative to native plant litter and alters ecosystem processes and functions that may facilitate exotic plant dispersal. However, these effects are largely unknown, especially within wetland ecosystems. This study examines whether introducing litter from theexotic mangrove Laguncularia racemosa could result in (1) accelerated community litter decomposition rates and increased nutrient cycling rates and (2)microbial community structure changes in the invaded areas. A single decomposition experiment using litterbags was conducted to examine the short-term effects of L. racemosa litter in the native mangrove forest ecosystem. The soil nutrients and microbial communities of Rhizophora stylosa, L. racemosa, and mixed forests were also compared to explore the long-term cumulative effects of L. racemosa litter in native ecosystems. The results indicated that L. racemosa has lower-quality leaf litter than R. stylosa and a significantly faster decomposition rate. This may result from changes in the soil microbial community structure caused by L. racemosa leaf litter input, which favors the decomposition of its own litter. Both the short-term and cumulative effect experiments demonstrated that L. racemosa leaf litter significantly increased the relative abundance of microbes related to litter decomposition, such as Proteobacteria and Bdellovibrionota, and enhanced the alpha diversity of soil fungi, thus creating a microbial environment conducive to L. racemosa leaf litter decomposition. Moreover, the accumulation of soil nutrients was lower under L. racemosa than under R. stylosa over several years. This may be related to the more rapid growth of L. racemosa, which causes soil nutrient absorption and storage within the plant tissues, thereby reducing the soil nutrient content. Inputting exotic mangrove L. racemosa leaf litter reduced the soil blue carbon content, potentially adversely affecting global climate change. L. racemosa may employ a unique strategy to lower soil nutrient levels in native mangroves based on its low-quality leaf litter, thereby weakening the competitive ability of native plants that are intolerant to low-nutrient conditions and enhancing its own competitive advantage to further spread into these areas. In summary, the input of exotic L. racemosa leaf litter accelerates nutrient cycling in local mangroves.

Stuck in the mangrove mud: The risk of trace element exposure to shore crabs in restored urban mangroves

The restoration of mangroves in urban environments can increase the risk of contaminant exposure and subsequent health effects to resident biota, yet this risk is rarely considered in mangrove restoration programs. Here we assessed the influence of sediment chemistry on contaminant bioaccumulation in shore crabs from restored and natural mangroves in urban environments compared to a reference site. The concentrations of some trace elements were several-fold higher in the sediment and crab tissues of the urban restored site compared to the natural reference site (Cd = 6×, Co = 7×, Cr = 4×, Mn = 30×, and Ni = 18× greater in sediments, while Cd = 4×, Co = 2×, Cr = 2×, Mn = 6×, and Ni = 3× greater in crab tissues). NMR-based metabolomics on crabs revealed higher abundances of proline and glutamate at urban sites, which may be indicative of physiological stress from trace element contamination. Choice experiments were used to test habitat selectivity by crabs from each population, and showed that crabs avoided sediments from the contaminated urban sites. Our results suggest that restoring mangroves in contaminated environments could create ecological sinks, where animals take residence in the new habitat but are exposed to sediment-based contaminants, with potential implications for organism and population health.

Spatial Differentiation of Mangrove Aboveground Biomass and Identification of Its Main Environmental Drivers in Qinglan Harbor Mangrove Nature Reserve

Spatial Differentiation of Mangrove Aboveground Biomass and Identification of Its Main Environmental Drivers in Qinglan Harbor Mangrove Nature Reserve

Assessing sediment CO2 effluxes in the coastal ecosystem of North Sumatra, Indonesia

Coastal wetlands including mangrove play a vital role in regulating the local and global carbon cycle. Coastal areas contribute greatly to the carbon exchange process due to the complex interactions that occur between the atmosphere, land, and oceans. One of the important components in coastal carbon dynamics is CO2 gas exchange between soil, water and the atmosphere. This study aims to assess CO2 efflux across various land covers (namely natural mangrove, restored mangrove, and converted mangroves to oil palm and aquaculture pond) in the coastal areas of North Sumatra Province, and analyze the effect of sea tides and ebbs on the rate of CO2 efflux and their connection with the number and area of macrozoobenthos burrows. We applied direct sampling by using the static closed chamber method attached to portable CO2 analyzer. The mean of CO2 efflux in natural mangrove forest land covers was 866±585 mgCO2/m2/h during low tide conditions and 1137±792 mgCO2/m2/h during high tide conditions, followed by oil palm plantations at 760.71±341 mgCO2/m2/h, restored mangroves during low tide of 575.24±326 mgCO2/m2/h and 597.11±180 mg CO2/m2/h during high tide conditions, and the lowest was recorded in ponds at 588.55±358 mgCO2/m2/h. Further, we observed that tidal conditions affect the magnitudes of CO2 efflux in natural and restored mangrove forests, and we did not observe similar pattern in oil palms and ponds since these land covers were not influenced by regular tidal input. We also observed that no significant relationship between the number and area of macrozoobenthos burrows and CO2 efflux. Our findings suggest that CO2 effluxes in coastal wetlands are highly dynamic and presumably driven by complex factors and therefore, understanding their magnitudes and drivers requires extensive measurement covering large spatial and temporal scales.

Exploring environmental condition of silvofishery pond to support the sustainability of mangrove management in Berau Regency, Indonesia

The integration of mangrove management with aquaculture, termed the silvofishery pond system, has been implemented in Berau Regency, East Kalimantan Province, Indonesia. A detailed survey was conducted to assess the features of mangrove terrain surrounding silvofishery ponds, aiming to enhance the productive and sustainable management of these mangrove areas in Berau Regency. This survey focused on various land characteristics such as topography, tidal patterns, water quality, soil properties, climate, and the state of mangrove vegetation. The health of mangrove vegetation was assessed by calculating the Important Value Index (IVI) across different growth stages: trees, saplings, and seedlings. The findings reveal that the mangrove adjacent to the silvofishery ponds in Berau Regency are home to 14 species from 13 genera and 10 families. Rhizophora mucronata displayed the highest IVI scores across all growth stages: 75.17% for trees, 93.14% for saplings, and 66.98% for seedlings, the latter shared with Rhizophora apiculata. Soil quality emerged as a critical limiting factor for land use in silvofishery ponds, particularly due to high potential acidity (low pH) and low nitrogen (N) content. To enhance soil quality, it is recommended that soil management practices such as remediation (via drying, submerging, flushing, or liming) and N supplementation through fertilization be employed. Furthermore, given the sparse mangrove vegetation density at the tree level (1,012 trees/ha), efforts to promote natural mangrove regeneration and prevent deforestation and degradation are advised. Considering the unique characteristics of the mangroves, the implementation of the komplangan model—a silvofishery approach that segregates mangroves restoration pond from grow-out ponds—is recommended to boost productivity and ensure sustainability in the coastal region of Berau.

Impact of Conservation in the Futian Mangrove National Nature Reserve on Water Quality in the Last Twenty Years

Mangroves play a crucial role in improving the water quality of mangrove wetlands. However, current research faces challenges, such as the difficulty in quantifying the impact of mangroves on water quality and the unclear pathways of influence. This study utilized remote sensing imagery to investigate the long-term changes in mangrove forests in the Futian Mangrove National Nature Reserve and constructed a water quality index based on water quality data. Finally, structural equation modeling was employed to explore the pathways of influence and quantify the impact effects of mangroves, climate, and water quality. The study findings revealed several key points: (1) The mangrove forests in the Futian Mangrove National Nature Reserve exhibited a trend of expansion towards the ocean during this period. (2) The seasonal and annual characteristics of water quality in Shenzhen Bay indicated a significant improvement in water quality from 2000 to 2020. (3) Mangroves have significant direct and indirect impacts on water quality, which are more pronounced than the effects of climate factors. These findings not only offer insights for the environmental management and conservation of Shenzhen Bay but also provide support for future comprehensive studies on the response relationships between the morphology, species, and physiological characteristics of mangroves and water quality.

Abundance and Distribution Patterns of Oysters (Saccostrea cucullata) in the Bagek Kembar Mangrove Area, West Lombok

An invertebrate critter called Saccostrea cucullata is typically found adhering to substrates like rocks and mangrove roots. The purpose of this study is to ascertain S. cucullata's abundance and distribution patterns. This study was carried out at West Lombok's Bagek Kembar Sekotong Natural Mangrove Area in February 2024. The samples were observed using the 5 x 5 m quadratic transect approach. To ascertain S. cucullata abundance and dispersion patterns, descriptive analysis was performed on the data. According to the study's findings, station I had the greatest abundance (1.81 Ind/m2), while station III had the lowest (0.95 Ind/m2). S. cucullata exhibits a clustered and uniform distribution pattern in certain areas. In the research region, temperature, salinity, and pH are the main factors affecting S. cucullata abundance and dispersion pattern, respectively.

Species pool and soil properties in mangrove habitats influence the species-immigration process of diazotrophic communities across southern China.

Microbial immigration is an ecological process in natural environments; however, the ecological trade-off mechanisms that govern the balance between species extinction and migration are still lacking. In this study, we investigated the mechanisms underlying the migration of diazotrophic communities from soil to leaves across six natural mangrove habitats in southern China. The results showed that the diazotrophic alpha and beta diversity exhibited significant regional and locational variations. The diazotrophic species pool gradually increased from the leaves to nonrhizosphere soil at each site, exhibiting a vertical distribution pattern. Mantel test analyses suggested that climate factors, particularly mean annual temperature, significantly influenced the structure of the diazotrophic community. The diazotrophic community assembly was mainly governed by dispersal limitation in soil and root samples, whereas dispersal limitation and ecological drift were dominant in leaves. Partial least squares path modeling revealed that the species pool and soil properties, particularly the oxidation-reduction potential and pH, were closely linked to the species-immigration ratio of diazotrophic communities. Our study provides novel insights for understanding the ecological trait diversity patterns and spread pathways of functional microbial communities between below- and aboveground habitats in natural ecosystems.IMPORTANCEEnvironmental selection plays key roles in microbial transmission. In this study, we have provided a comprehensive framework to elucidate the driving patterns of the ecological trade-offs in diazotrophic communities across large-scale mangrove habitats. Our research revealed that Bradyrhizobium japonicum, Marinobacterium lutimaris, and Agrobacterium tumefaciens were more abundant in root-associated soil than in leaves by internal and external pathways. The nonrhizospheric and rhizospheric soil samples harbored the most core amplicon sequence variants, indicating that these dominant diazotrophs could adapt to broader ecological niches. Correlation analysis indicated that the diversities of the diazotrophic community were regulated by biotic and abiotic factors. Furthermore, this study found a lower species immigration ratio in the soil than in the leaves. Both species pool and soil properties regulate the species-immigration mechanisms of the diazotrophic community. These results suggest that substantial species immigration is a widespread ecological process, leading to alterations in local community diversity across diverse host environments.

Analysis of tourism destination management strategies of angke kapuk mangrove nature tourism park as an ecotourism destination in North Jakarta to increase interest in returns

Analysis of tourism destination management strategies of angke kapuk mangrove nature tourism park as an ecotourism destination in North Jakarta to increase interest in returns

Loss of microbial functional diversity following Spartina alterniflora invasion reduces the potential of carbon sequestration and nitrogen removal in mangrove sediments—from a gene perspective

Mangrove ecosystems play an important role in carbon (C) sequestration and nitrogen (N) removal. Although Spartina alterniflora has successively invaded native mangrove habitats during the preceding two decades, the effects of this invasion on the microbial functional potential involved in nutrient cycling remain unclear. In this study, metagenomic sequencing was used to investigate microbial C and N cycling in sediments derived from S. alterniflora and three native mangrove species (Kandelia obovata, Avicennia marina, and Aegiceras corniculatum). Greater differences in functional profiles of C and N cycling-related genes were observed between S. alterniflora and mangrove sediments than between different mangrove sediments. Functional diversity was lower in S. alterniflora sediments than in native mangrove sediments. The growth of Thaumarchaeota and Proteobacteria, was enhanced due to their resilience to diversity loss, while the growth of oligotrophs, such as Chloroflexi and Firmicutes, was inhibited in S. alterniflora sediments. Compared to mangrove sediments, the abundance of genes involved in C fixation and methane production was lower in S. alterniflora sediments. However, S. alterniflora significantly increased the gene abundance of pmo which controlled the oxidation process of CH4 to carbon dioxide. Additionally, genes involved in nitrification were enriched, whereas genes involved in N reduction processes, such as denitrification and dissimilatory nitrate reduction to ammonium, N immobilization, and N mineralization, were depleted in S. alterniflora sediments compared to mangrove sediments. Partial least squares regression models demonstrated that the decrease in soil organic C and increase in pH after S. alterniflora invasion induced the loss of microbial functional diversity, which was the main driver of changes in the abundances of genes involved in C and N cycling. Overall, our findings indicate that S. alterniflora invasion modifies the microbial functional profile of nutrient cycling in native mangrove ecosystems and potentially weakens the capacity of mangroves to sequester carbon and remove nitrogen.

Unveiling sedimentary microbial communities: Restored mangrove wetlands show higher heterogeneity and network stability than natural ones

Mangrove wetlands, characterized by high biodiversity and crucial ecological functions, have witnessed extensive restoration efforts in China in recent decades. Despite the successful recovery of standing vegetation, the alterations in below-ground microbial communities, vital engines for completing biogeochemical cycles in wetlands, remain poorly understood. Here, the prokaryotic and microeukaryotic communities in restored mangrove forests (RMF) and natural mangrove forests (NMF) in Shenzhen, the world’s first International Mangrove Center in China were investigated and compared. This work aimed to explore an appropriate sampling strategy for sedimentary microbial community biodiversity study and evaluate their heterogeneity and network stability in RMF and NMF. The results revealed that a “broad-coverage and sparse-spot” sampling strategy was conducive to ensuring a sufficient representation of microbial diversity in mangrove wetlands. Significant differences were found in microbial community structures of RMF and NMF, with the relative abundances of Myxococcales and Cerozoa as potential biomarkers, respectively. RMF displayed higher prokaryotic richness, microbial community dissimilarity, and spatial turnover rate compared to those of NMF, indicating greater microbial diversity and spatial heterogeneity in RMF. Meanwhile, the RMF microbial network was characterized by lower complexity but higher modularity, robustness, and the ratio of negative to positive cohesion. These demonstrated that microbiomes were shaped by stability constraints and the RMF microbial network was more stable and resistant to environmental variations than that of NMF. Interestingly, the stability of these microbial networks appeared to depend on the topological roles of key species rather than on their abundance. Overall, this study disclosed a kind of relationship between the aboveground elements of restored and natural mangrove forests and their belowground microbial communities. These findings provide references for comprehensive assessments of biodiversity, stability, and ecological restoration in mangrove ecosystems.

Archaeal communities in natural and artificially restored mangrove sediments in Tieshan Bay, China

Mangrove forests are crucial wetland ecosystems located in tropical and subtropical intertidal zones, but they have become extensively degraded. As a viable ecological restoration strategy, the cultivation of native mangrove vegetation in these degraded areas has gained considerable attention. Mangroves’ unique environmental conditions make them suitable habitats for diverse microbial communities, including Archaea - one of the main microbial communities in mangrove sediments - which plays a pivotal role in biogeochemical cycles. However, little is known about the dynamics of archaeal communities during mangrove restoration through phytoremediation. In this study, we investigated the physicochemical properties of sediment profiles from natural and artificially restored mangrove ecosystems in Tieshan Bay. We utilized quantitative polymerase chain reaction (qPCR) and 16S rRNA gene sequencing techniques to explore differences in abundance, community structure, and composition of archaeal communities between sediment profiles in natural and artificially restored mangrove ecosystems. We also examined correlations between archaeal communities and environmental factors. Our results revealed that Crenarchaeota, Thermoplasmatota, Asgardarchaeota, Nanoarchaeota, and Euryarchaeota were the predominant archaeal phyla, with significant variation in sediment composition observed for Crenarchaeota and Thermoplasmatota in different depths. We also found significant differences in archaeal abundance and community composition between natural and restored mangrove sediments. Furthermore, C/N ratio and pH emerged as primary drivers of archaeal communities in wet and dry season sediments, respectively. Additionally, the study revealed seasonal disparities in seasonal differences in the relative abundance of certain archaeal groups (such as Asgardarchaeota, Nanoarchaeota). Network analysis demonstrated stronger interconnections among archaeal communities in sediments from natural mangroves than from artificially restored ones. These findings enhance our knowledge of archaeal community succession patterns in mangrove restoration, as well as provide fresh perspectives for the sustainable management of mangrove ecosystems.

Natural mangrove associated gastropods at Bengkalis island, Riau Province, Indonesia: prelimanary survey

Abstract Mangroves have different natural and unnatural conditions and are known as marine habitats. The aim of this research was to determine the relationship between gastropods and environmental conditions for monitoring mangrove rehabilitation. The research was conducted from 8th to 16th October 2023 at Bengkalis Island, Riau Province, Indonesia. This research used a survey method with observation of mangroves, marine biota, and environmental parameters on landward, mid ward and seaward. The measurement of marine biota was conducted using a transect of 25 cm x 25 cm and environmental parameters included pH using a pH meter, salinity using a refractometer, and sediment type analysis. pH and salinity values ranged from 5-8 and 14-35 psu. The number of gastropods found was 5 (five) specimens in Bengkalis Island. In general, based on morphology, the weight of each of the largest showed T. telescopium > L. angulifera > C. cingulata > C. obtusa > C. angulifera. The results showed that natural mangroves described more various gastropods. Salinity and pH can also be used as a major limiting factor for mangrove rehabilitation monitoring.

The Role of Youth in Maintaining Mangrove Trees and Nature in Kedah, Malaysia

The Role of Youth in Maintaining Mangrove Trees and Nature in Kedah, Malaysia

Impacts and implications of anthropogenic activities on mangrove forests: A review

The purpose of this paper is to review and evaluate published literature on the causes, impacts, implications and mitigation strategies of anthropogenic activities on mangrove forests. A systematic method was utilized to access research works of literature on “Impacts and implications of anthropogenic activities on mangrove forests”. A total of fifty-three (53) research papers published between the years 1975 to 2024 was accumulated and used for this review. A subjective approach was used to select the topics: impact and implications of anthropogenic activities on mangrove forests. In this paper, five (5) roles of mangroves were assessed and presented. Anthropogenic activities that threaten mangrove forests such as land conversion, mining and logging activities and household and industrial activities were also evaluated. Further, four (4) detrimental anthropogenic activities and the potential impacts they have on natural mangrove forests and the ecosystems they thrive in was also reported on. In addition, this paper reviewed some mitigation strategies for sustainable management and conservation of our mangroves, their ecosystems and the coastlines. The published works of literature established that reduced mangrove forests, altered mangrove composition, unequal species abundance, mass mangrove mortality, pollution in mangrove areas, rising sea levels, global climate change and coastal erosion or abrasion are all effects of anthropogenic activity that have a negative impact on mangrove forests and the ecosystems. This review highlights the fact that more studies on the impact and implications of anthropogenic activities on mangroves should be done in neotropical countries since there are paucity of such information on research and published data in these biodiversity rich regions.

Tidal zone effects on the diet composition of leaf-eating crabs in natural mangrove communities: a stable isotope analysis

BackgroundIn natural mangrove communities, mangrove species are often distributed zonally. Leaf-eating crabs are one of the most abundant and iconic arboreal brachyurans in mangrove forests, but variation in the composition of crab diets in different mangrove tidal zones is unknown.MethodsTo determine the contributions of mangrove leaves and other organic carbon (C) sources to leaf-eating crab diets, dual stable C and nitrogen (N) isotope signatures (δ13C and 1δ5N) were used in a Bayesian stable isotope mixing model. We conducted experiments at various tidal levels in the Dongzhaigang Bay National Natural Reserve in China. We analyzed δ13C and δ15N of leaf-eating crabs, mangrove leaves, sediment organic matter (SOM), and animal tissues (prey).ResultsThe food composition of the dominant crab species, Parasesarma continentale, exhibited significant differences among the four tidal zones. From the margin to the high tide zone, the main food source shifted from predominantly mangrove leaves and SOM to primarily SOM and animal tissues. We observed a significant negative relationship between the C/N ratios of mangrove leaves and the proportion of leaves consumed by leaf-eating crabs. Additionally, as the tidal level increased, the C/N ratio of mangrove leaves also increased, whereas the proportion of leaves consumed by crabs decreased.ConclusionLeaf-eating crab diets vary significantly across tidal zones, highlighting the importance of considering tidal zone differentiation when studying consumer diets in mangrove ecosystems.

Subtropical mangroves poleward shift to the Yangtze Estuary under different carbon emission scenarios

Mangroves are crucial plant communities in the coastal intertidal zones, providing various ecological services and supporting biodiversity. To identify the primary factors affecting the poleward shift of subtropical mangroves and the northernmost extent of subtropical mangroves under various carbon emission scenarios, the MaxEnt model was utilized with presence data of subtropical mangrove and environmental data under different carbon emission scenarios. Kandelia obovata, Avicennia marina, and Aegiceras corniculatum in China were included for modeling, utilizing 22 bioclimate variables to predict mangrove distributions, and kernel density analysis was further employed to identify conservation and afforestation hotspots for mangroves. The results indicated that the number of days below 10 °C per year is the major climatic factor shaping the distribution of subtropical native mangroves, while precipitation exerts a relatively lower contribution. Under the low and medium emissions scenarios (SSP126 and SSP245), the northern boundary of the distribution of K. obovata remains stable, while A. marina and A. corniculatum are projected to shift northward to Fuzhou, Fujian Province (26.1°N) from 24.9°N by 2100. Under higher emissions scenarios (SSP370 and SSP585), the suitable habitat of K. obovata is expected to shift north to the mouth of the Yangtze River (31.9°N) from 26.8°N, and A. marina and A. corniculatum are projected to move northward to the coastal area of Ningde, Fujian Province (26.8°N) by 2100. In conclusion, with the increase in carbon emissions, there is a significant northward migration observed in subtropical native mangroves (p < 0.01), and suitable areas for restoration in China have been identified, with the northernmost region located in Zhejiang Province. The spatial and temporal patterns of range change predicted in this study provide valuable information for conservation and afforestation strategies for these ecologically important species.

Tracking the long‐term vegetation and soil characteristics of restored mangroves: a case study from Guyana's coast

The global urgency to halt and reverse mangrove loss has led to the implementation of numerous initiatives to protect and restore mangroves and recover critical ecological functions and services. Restoration success is assessed by estimating mangrove survival, while diversity, vegetation structure, and soil characteristics are often overlooked with no long‐term monitoring. Here, we investigated long‐term changes in vegetation and soil characteristics of Avicennia germinans‐dominated stands planted along Guyana's coast between 5 and 11 years old. A chronosequence approach was used to examine changes in vegetation and soil parameters in restored mangrove stands of different ages compared to natural stands of the same ages. Tree height, diameter, and aboveground biomass were inconsistent between restored and natural mangrove stands. Redundancy analysis (RDA) revealed that the soil properties were the important factors influencing both the restored and natural mangrove communities. There were no clear trajectories between the vegetation and soil characteristics with age, possibly due to site‐specific and hydrodynamic environmental factors, such as tidal dynamics, riverine inputs, and climatic variations. While there were some equivalent vegetation and soil characteristics at the end of the first decade after restoration, the restored mangroves may require a longer timespan (approximately 25 years) than the period overserved in our study to be entirely identical to the natural mangroves. This case study from Guyana provides valuable insights into the ecological processes driving mangrove recovery dynamics, growth patterns, and restoration effectiveness and offers reliable data needed to inform future restoration projects.

The inputs of autochthonous organic carbon driven by mangroves reduce metal mobility and bioavailability in intertidal regions

The significance of mangroves in carbon storage is widely acknowledged. However, the potential role of carbon enhancement driven by mangroves in mitigating the risk of metal exposure remains unclear. In this study, a natural mangrove reserve located in Futian was selected to investigate the potential role of autochthonous organic carbon on metal bioavailability. The presence of mangroves seemed to have little effect on the accumulations of Cu(II), Zn(II), Cr(VI/III), Pb(II), and Ni(II) in surface sediments. Metal mobility and bioavailability, however, were found to be directly influenced by the presence of mangroves. Compared with mudflat, mangrove sediments exhibited an obvious in the bioavailability of Cu(II), Zn(II), Cr(VI/III), Pb(II), and Ni(II) by 19–79 %, with the highest reduction occurring in the interior of mangroves dominated by K. obovata. Mangroves also significantly enhanced the accumulation of organic carbon in sediments, regardless of carbon components. Moreover, the results from random forest analysis further showed that autochthonous organic carbon was the most important carbon component that negatively related to metal bioavailability. In summary, this is the first study to provide a linkage between mangrove cover and increased autochthonous organic carbon input, which decreases metal bioavailability. The present data also suggest that mangroves are an efficient natural barrier to alleviate the risk of metal exposure in intertidal regions.

Two new diatom species of the genus Gomphonemopsis (Bacillariophyceae) from the coast of China and two new combinations for the genus.

Two new diatom species belonging to the genus Gomphonemopsis are described, Gomphonemopsisnanasp. nov. and Gomphonemopsisgaoisp. nov. These two species were compared in detail with congeners. Gomphonemopsisnana is distinguished by its high stria density and small size. This species was found so far to be epiphytic only on the eelgrass collected from Qingdao Bay (Yellow Sea). Gomphonemopsisgaoi is characterized by its isopolar valves, simple proximal raphe endings and acutely rounded apices. This taxon was separated from the exoskeleton of marine copepods sampled from the Futian Mangrove Nature Reserve (South China Sea). In addition, two new combinations, Gomphonemopsisoahuensis (Hustedt) Lang Li, Yuhang Li & Changping Chen, comb. nov. and Gomphonemopsisplatypus (Østrup) Lang Li, Yuhang Li & Junxiang Lai, comb. nov. are proposed. This study increases the records and knowledge of Gomphonemopsis along the coast of China.