Mangrove Density Research Articles

Research on the Ecological and Economic Impacts of Rising Sea Levels on Mangroves in Southern Florida in the Context of Climate Change

The decline in mangrove ecosystems is a major contributor to the loss of biodiversity, extra carbon release, and local economic instability, particularly in tropical coastal regions that are constantly influenced by climate changes. Despite the importance of the mangroves, there is limited research investigating the consequences. Under the context, this research examines the correlation between mangrove density, sea level rise, and economic impacts in Southern Florida. The work aims to address three main questions: (i) what are the ecological impacts of sea level rising on mangroves density; (ii) what are the economic implications of mangrove loss; (iii) what extent of government intervention should be imposed on the environmental problem. The research presents a two-variable graph that examines the relationship between mangrove density in Southern Florida and sea level rise, analyzing its overall correlation in the Caribbean region. Another correlation study of the impacts of mangrove loss on local tourism is created and set as the focus. The conventional hedonic method is applied as the tool of evaluating mangroves value. The results demonstrate a close negative correlation between sea level and mangrove density, and a positive correlation of mangroves density and local tourism.

Mangrove Density Mapping from Landsat 8/9 OLI Imagery in Dompak Island, Indonesia: A Study from 2017 to 2022

Dompak Island, a small island in the Riau Islands Province, has experienced massive urban development by local governments over the last decade. This activity has impacted the sustainability of vegetation and mangrove forests on Dompak Island. A decrease in the mangrove area can affect the condition and sustainability of the species. This study aimed to analyze the changes in mangrove density using Landsat 8/9 OLI satellite imagery of Dompak Island, Tanjungpinang City, from 2017 to 2022. This study used an unsupervised classification method, which used the Normalized Difference Vegetation Index (NDVI) to identify the changes and density of mangroves, and an algorithm to obtain the greenness value of vegetation objects. This study found changes in the area and growth of mangroves. There is a decrease in mangrove density globally. The level of rare density in 2017 and 2022 was still at 23%, the medium density increased by 8%, and the high density decreased by 9%. Based on mapping results, the area of mangrove forests has decreased by 4 ha from 2017 to 2022, namely from 93 ha to 89 ha..

Ecological status of threatened mangroves Ceriops decandra and Merope angulata in mangrove ecosystem Segara Anakan Lagoon, Central Java, Indonesia

Mangrove ecosystem Segara Anakan Lagoon (SAL), is the largest mangrove ecosystem in Java that is occupied by various types of mangroves. Several studies have shown the deforestation of mangrove in SAL which caused the decrease of mangrove biodiversity and species density. This study aims to obtain updated information on the distribution and density of two mangrove species found in SAL that are listed in the IUCN, which are Ceriops decandra (Threatened) and Merope angulata (Least Concerned). This research was conducted with the stages of literature study and analysis of satellite imagery using Sentinel 2 and the NDVI equation to obtain the change of mangrove cover and density. The literature study found that C. decandra was mostly distributed in the eastern and central sites of the Lagoon, while M. angulata was distributed in the center site. According to the spatial analysis, the density of Ceriops decandra was found >0,5 while Merope angulata is distributed in the center site with a medium density categorized. The degradation of the mangrove ecosystem in 2023 was estimated to be 10.493,64 ha. The information provided in this study is expected to improve conservation and protection actions for the sustainability of the threatened mangroves species in SAL.

Bivalve Spat (Anadara granosa) recruitment in rehabilitation mangrove ecosystem of Rangsang Island, Riau province

Southeast Asia's mangrove areas are inhabited by several bivalves, such as the blood clam (Anadara granosa), which are widely distributed in intertidal areas. The importance of economic value of bivalves causes the availability of seeds to be very important. Knowing the abundance and life cycle of bivalves (Anadara granosa) is the right step in estimating the ideal time to collect bivalves in an ecosystem. This study aimed to determine the abundance and time of attachment of bivalves (Anadara granosa) seeds in the rehabilitation mangrove ecosystem on Rangsang Island, Riau. The sampling method used is purposive sampling, consisting of two subzones, and each subzone is located in the intertidal zone, namely at the point of the highest tide and the highest low tide in the mangrove forest area. The results showed that A. granosa was more common in December (79100 ind/100 m2) with an average length of 7.67 (±3.94). The relationship between mangrove density and abundance of A. granosa has a strong relationship in December and January, with the length range of A. granosa being influenced (strong category) by pH and temperature.

Analysis Of Vegetation Index For Ndvi, Evi-2, And Savi For Mangrove Forest Density Using Google Earth Engine In Lembar Bay, Lombok Island

The mangrove forest is one of the most productive ecosystems in the world. Mangrove forests have benefits such as flood control, groundwater conservancy, shoreline and storm protection, biodiversity conservation, mitigation, and adaptation to climate change. Remote sensing for monitoring and mapping natural ecosystems such as mangrove forests has increased recently. The advantage of using remote sensing data for mapping mangrove forests lies in the remote sensing imagery that provides a comprehensive view compared to land-based measurements. The easily-recognizable appearance of mangrove vegetation in the image is because mangrove vegetation lives between land and sea transitions; thus, the mangrove vegetation has a darker color appearance. The vegetation index algorithm is an algorithm that can see the condition and density of mangrove forests. Therefore, the Google Earth Engine platform can be utilized. It has a very large remote sensing data set; thus, it can process and discover the density value of mangrove forests the results of the vegetation index values with the NDVI, EVI-2, and SAVI methods. The location of this research is in Lembar Bay. The results of this study indicate that sentinel imagery 2A level 2A can be used to generate vegetation index data using the NDVI, EVI-2, and SAVI algorithms. Based on the vegetation index classification with NDVI, EVI-2, and SAVI, it is known that the dominant density level is a very high density, with an area of 56,66 ha for NDVI, 50,24 ha for EVI-2, and 56,65 ha for SAVI. Then the correlation between NDVI, EVI-2, and SAVI with water and soil parameters that have the most influence on mangrove vegetation density is water pH with a correlation coefficient value of NDVI 0,464, EVI-2 0,469, and SAVI 0,464, showing that water pH and vegetation index have a strong enough correlation.

KOMPOSISI JENIS DAN KONDISI MANGROVE DI TELUK GILIMANUK, TAMAN NASIONAL BALI BARAT

Mangrove ecosystems have an important role, both for biota and humans. The level of density and mangrove cover is one illustration to determine the level of damage to mangroves. This study aims to determine the species composition and the level of mangrove damage based on the density and percentage of canopy cover of mangroves in Gilimanuk Bay. This research was conducted in February 2021. The determination of the sampling point was carried out using the purposive sampling method. Mangrove data retrieval was performed using a plot 10x10 m2 with a total number of plots were 31 plots. The results showed that there were 11 types of mangroves from 7 different families in Gilimanuk Bay. The most common type of mangrove found was Ceriops tagal (45,84 %) and the least was Xylocarpus granatum (0,13 %). Mangrove density in Gilimanuk Bay is 2390,32 ind/ha, and canopy cover is 83,84%, which shows that the condition of mangroves in Gilimanuk Bay is included in the good category (very dense).
 Keywords: Mangrove; Gilimanuk Bay; Density; Canopy coverage

ESTIMASI SIMPANAN KARBON PADA BIOMASSA MANGROVE DI TAHURA NGURAH RAI

Mangroves contribute to mitigating climate change by storing carbon. As mangrove forests have a high rate of carbon sequestration and storage, carbon stock calculations are required to quantify the accumulation of carbon stored in a site to determine its involvement in decreasing greenhouse gas emissions. This study aims to estimate carbon storage at the Mangrove Information Center (MIC) by using an allometric calculation of the mangrove above-ground biomass data. Data collection was carried out on January 10-14, 2022 at the MIC, with an area of 322 ha. The method used is a 1000 meters line transect plot divided into 15 measuring plots in three mangrove ecological zones (front, middle, and back). Biomass data were taken in a non-destructive way based on measurements of the circumference girth at breast height (GBH) and the results were calculated using allometric. According to data analysis, the average total surface biomass of mangroves in MIC is 781.30 kg, with estimated carbon storage in MIC is 36,727 tons/ha. Overall, the total carbon stock in the stratum MIC is 11.826,253 tons. The highest estimated carbon storage is in Plot 9, which is 91,799 tons/ha, while the lowest estimated carbon storage is in Plot 2, which is 13,873 tons/ha. The high numbers of carbon storage from mangrove above-ground biomass are mostly found in the middle and front zones because of the very dense mangrove density.
 Keywords: mangrove; above-ground carbon estimation; climate change mitigation

Mangroves in Southeast Aru Marine Protected Area

Southeast Aru Marine Protected Area (MPA) is a 114,000 hectares reserve-type national conservation area in Arafura Sea, Maluku Province, Indonesia where the Ministry of Marine Affairs and Fisheries managed since 2009. Its mangrove is the largest coastal ecosystem which is important for sustainable fisheries and coastal disaster mitigation. The main objective of this study is to understand the condition of mangrove community, its impact on fisheries and threats to its continuity. Stratified random sampling on three plots of 10 m x 10 m and hemispherical photography are employed on 13 observation sites across four zones. Local fishermen are interviewed about their activities related to mangroves. From 13 observation sites, 19 species from 8 families and 10 genera are identified. The average of mangrove density and its canopy coverage were respectively 2,997 stand/ha and 74.66%. These values can be interpreted as in good condition and moderate coverage (KepmenLH 201/2004). Rhizophora mucronate and Sonneratia alba are the two most dominant species in all observation sites. Local fishermen’s activities in the mangrove area are catching crabs, trap-fishing, and cutting mangrove woods for firewood and/or simple non-permanent housing. Bruguiera gymnorrhiza, Phemphis acidula, Rhizophora mucronate and Ceriops tagal are their favourites.

PEMANFAATAN CITRA SATELIT LANDSAT 8 UNTUK MEMETAKAN HUTAN MANGROVE WISATA BAHARI PANTAI KARANGANTU, TELUK BANTEN

Mangrove marine tourism is one of the tourism sectors involved in large and important projects in tourism development. The transformation of PPN Karangantu from a protected area to marine tourism has caused environmental damage. This continued focus on mass tourism has resulted in environmental damage and pollution of the mangrove area found in PPN Karangantu. The aim of the study was to calculate the area of mangrove forest, the accuracy value of mangrove density and changes in conditions due to the existence of the Karangantu Beach marine tourism area in the last 5 years. The research method uses a mixed method to identify mangrove areas by visually analyzing landsat 8 spectral values using the Google Earth Engine (GEE) platform and by image processing for 2018-2022. The results showed that in 2018 the area of mangrove land was 17.04 ha, which decreased drastically in 2019 to 6.28 ha due to an oil spill that was carried away from Karawang Waters. In 2020 it will be 10.6 ha, in 2021 it will be 9.56 ha and in 2022 it will be 7.32 ha. This decrease area is due to marine tourism activities which damage the mangrove ecosystem land and many visitors do not protect the ecosystem. The use of GEE can provide an overview of the capabilities of Landsat 8 satellite imagery in mapping the mangrove forests in Karangantu Beach.

Mapping of Mangrove Ecosystem In Segara Anakan Lagoon using Normalized Different Vegetation Index and Dominant Vegetation Index

Mangrove ecosystem in Segara Anakan Lagoon (SAL) Cilacap as a typical and specific semiclosed estuary. SAL is dominated by many species like as Rhizophora spp., Sonneratia spp., Bruguiera spp., Avicennia spp., and other species. The normalized different vegetation index (NDVI) and dominant vegetation index (DVI) are a suitable method to support the mapping analysis of mangrove structure and mangrove density. This research aimed to develop mapping of mangrove species distribution, density and dominated species using NDVI and DVI. The method of this research used NDVI analysis using satellite imagery 2017-2020 and domination vegetation with line and quadrat transect method. The results showed that West Segara Anakan had mangrove dense (25 %), moderate density (25 %), rare density (50%) and East Segara Anakan had mangrove dense (43,86 %), moderate density (47.99 %), rare density (8,24 %). Based on domination species showed that East Segara Anakan was dominated by Rhizophora stylosa (233-1633 trees ha-1), Rhizophora apiculata (100-1067 trees ha-1), Nypa frutican (50-2775 trees ha-1), whereas West Segara Anakan was dominated by Nypa frutican (565-2333 trees ha-1), Avicennia marina (198-933 trees ha-1), Sonneratia caseolaris (132-700 trees ha-1) and Avicennia alba (107-1000 trees ha-1). Keywords : Mangrove density, mapping analysis, Segara Anakan Lagoon, NDVI and NDWI

Bibliometric and meta-analysis studies of the correlation between macrozoobenthos abundance and mangrove density

Several attempts have been made to detect the condition of the mangrove ecosystem. Although the method used to detect the state of the mangrove ecosystem faces numerous challenges, it has yet to describe the functional structure of the mangrove ecosystem about its environment. Therefore, this study provides an overview of research trends regarding the relationship between macrozoobenthos abundance and mangrove forest density. This study aims to conduct bibliometrics and meta-analysis related to the abundance of macrozoobenthos and mangrove density. First, a bibliometric analysis to see research gaps using VOSviewer, the source of bibliometric data comes from GScholar and Scopus with the keywords mangrove search and meta-analysis. The number of articles filtered and processed using VOSviewer is 497 articles. After looking for gaps, the researchers conducted a meta-analysis to see the relationship between the abundance of macrozoobenthos and the density of mangroves. This study shows that no meta-analysis discusses the relationship between macrozoobenthos abundance and mangrove density. The results of the meta-analysis process found a strong relationship between mangrove density and macrozoobenthos mass with a significance value of < 0.001 and I^2 = 97.37.

Mangrove rehabilitation planning with ecological and geospatial approaches in Cemara Village, Indramayu, West Java

Several rehabilitation activities have been carried out by the government in Indramayu Regency, but have not been able to restore the condition of the mangrove. Hence, it is necessary to rehabilitate potential land. The aim of this study is to formulate the direction of rehabilitation planning in Cemara Village, Indramayu based on an ecological approach and mangrove ecosystem. The method used in this study is geospatial approach that is integrated with field quantitative data. The result shows that the total area that is potential to be rehabilitated in Cemara Village is 1,012.020 ha, which consists of 285.390 ha (28.2%) vegetated area and 726.630 ha (71.8%) non-vegetated area. Furthermore, the plan of rehabilitation in Cemara village is based on the consideration of mangrove typology, mangrove stand density, physical parameters, and land use. Recommendation for rehabilitating mangrove forest on land with low mangrove density and emergent land by performing intensive planting, on pond land by performing sylvofishery planting, on land with moderate mangrove density by enrichment planting, and on land with high mangrove density by carrying out maintenance for protective function.

Sustainability level of Silvofishery ponds on the coast of Semarang City

Silvofishery ponds are aquaculture areas while maintaining their ecological functions as conservation of mangrove ecosystems. Coastal community of Semarang City is one of those that cultivate it, and the main commodity is milkfish (Chanos chanos). This research was carried out on five dimensions; ecology dimension, economic dimension, social dimension, technological dimension, and ethics dimension using the RAPFISH (Rapid Appraisal for Fisheries) analysis method. Types of ponds developed in the design of komplangan. The level of sustainability of the silvofishery ponds management is 43.02%, with less sustainable categories in different indexes and dimensions, namely: The ecological dimension 32.02% (less sustainable), economic dimension 45.63% (less sustainable), social dimension 50.61% (entirely sustainable), technological dimension 49.77% (less sustainable), and ethics dimension 36.06% (less sustainable). The results of the leverage analysis on each dimension indicate the need to improve the management of sensitive attributes in each dimension. Sensitive indicators in Silvofishery ponds management are ecological dimension (mangrove density), dimension (market orientation), social dimension (access to use by the community), technological dimension (air circulation), ethics dimension (non-formal institutions). All measurements have a Monte Carlo value that difference is <1; therefore, the results of the Silvofishery ponds management are following the real conditions in the field.

Current status and trends of research on microplastic fugacity characteristics and pollution levels in mangrove wetlands

Microplastics have been widely detected in the environment, while mangrove wetlands are considered barriers to land-based plastic transport to the ocean, requiring special attention. However, the current literature is distributed and broad besides limited information on the fate characteristics and pollution levels. This study uses a systematic literature review method to analyze the current research status and future trends. In this study, the literature is summarized and concluded that Characteristics including color, shape, size, polymer chemistry and surface microstructure are the basic information for microplastic research in mangrove wetlands. Size is the key to studying distribution and convergence without international standards. The shape is vital to study its sources and environmental processes. Color affects biological predation and is important information for studying ecological risk. The chemical composition of plastics is the key to studying microplastics’ fingerprint information, source, and sink. The surface microstructure is an important basis for studying adsorption behavior and aging processes. Mangrove microplastic studies in China are mainly on the southern and southeastern coasts, and microplastic pollution is more severe in Fujian, Guangdong, and Guangxi than in Hainan. In contrast, studies on mangrove microplastics abroad are mainly concentrated in Southeast Asia, the Middle East, and South America. Overall, microplastic contamination was detected in the major distribution areas of mangroves worldwide and was correlated with mangrove density and human activities.

Mangroves and the Sustainability of Longtail Shad Fish (Tenualosa macroura) in Riau Province Water, Indonesia

Mangroves are crucial to fisheries as nurseries; they can be used as spawning and feeding grounds for fish, including Longtail Shad fish (Tenualosa macroura). The objective of the study was to analyze the mangrove vegetation used as Longtail Shad fish spawning ground. It was carried out from January to May 2021, using a checkered line method with six sampling stations. Each station was placed in three transects with three plots for each transect. Density, relative density, frequency, relative frequency, dominance, relative dominance, and importance value index were included in the vegetation analysis. There were 13 true mangrove types and 1 mangrove associate type at the study locations. The highest mangrove density was found at Station 3 with 3300.48 Ind/Ha, categorized as good. The highest mangrove coverage was found at Station 2, with an exceptionally dense category (76.34%). The regression analysis revealed a substantial relationship between density and mangrove and the water salinity at a 0.002 significance value (<0.05). Based on the gut content analysis in establishing the fish's eating habits, the type of food consumed by the Longtail Shad fish was mostly mangrove litter, representing 44.66% of the total stomach contents. The result of the study clearly shows that mangroves are crucial for Longtail Shad fish. A good mangrove ecosystem will provide good water quality for the migration process of longtail shad fish and produce mangrove litter as fish food. Mangrove ecosystem management can support the management of Terubuk fisheries.

Structuring the Bruguiera gymnorrhiza Mangrove Area for Food Security in Paciran Village, Paciran District and Labuhan Village, Brondong District, Lamongan Regency, East Java

The results of the GSCA show that the Bruguieragymnorhiza mangrove forest is an alternative source offood for local people that can be mixed with rice, and madevarious kinds of food diversification. The NDVIresults show that the mangrove density with the dominanceof Bruguiera gymnorhiza species needs to berehabilitated and restored to increase its density anddensity. Considering that the location of the mangroveforests in the two research villages is in water areas, it isnecessary to have a policy to convert rice fieldsback to the growth of mangrove land. The policy of theLamongan district government which is containedin the strategic plan policy to optimize coastal land into thedevelopment of residential areas, industrialareas need to be updated and revised into protected areas. Mangrove forest areas are managed for the useof mangrove forests as an alternative to food by dividingthe area into a no-take zone and a limited economicarea that can only be used as a food source area for thecommunity.

Spider (Arachnida: Araneae) diversity at Godrej mangroves, Vikhroli, Mumbai, Maharashtra, India

Among the varied aquatic and terrestrial invertebrates diversity of mangrove ecosystem, spiders are considered to be an important bioindicators of ecological health. Studies on the spider diversity in the mangroves at Vikhroli, Mumbai, Maharashtra conducted resulted in the documentation of a total of 38 spider species belonging to the 33 genera under 12 families. Salticidae was found to be the dominant with 10 species from 10 genera, followed by Araneidae (9 species and 7 genera). The survey done in three mangrove zones revealed that zone II with moderate mangrove density resulted in the highest diversity (H=0.89) of spiders. Guild structure analysis revealed six different guilds. Stalkers (Salticidae and Oxyopidae) were the predominant feeding guild (34.00%). Seasonal (pre monsoon, monsoon and post monsoon) analysis showed more species diversity in the month of June to September.

Mollusk Diversity in Percut Sei Tuan Silvofishery Ponds, North Sumatra, Indonesia

Highlight Research We found 16 species of mollusks with a total of 15 species from the gastropod class and 1 species from the Bivalvia class bivalves in the silvofishery ponds, recording a total of 369 individuals. The density of mollusks in July in pond I was 3.6 ind/m2, while it was 10.66 ind/m2 in pond II. The mollusk diversity index in October after rehabilitation was included in the high diversity category because the value of H' was 1.6 - 3.0. Pond I has a diversity index value of 1.89 and pond II 1.82. The value of C-organic concentration in both ponds ranged from 3.00% to 5.72%, which is the optimum level for mollusk growth. Abstract Silvofishery is a system that combines mangrove and fishery to protect mangrove ecosystems and restore their functions, one of which is as a habitat for macrozoobenthos. Investigate the mollusks and mangrove density. Mollusk sampling was carried out on sub-plots measuring 1 x 1 m² in the mangrove vegetation transect, and mangrove density was measured by counting the number of trees directly on all of the mangrove species at two silvofishery ponds. A total of 16 species of mollusks were found at the observation site, consisting of gastropods and bivalves. The density of mollusks in July was 20 ind/m2 in pond I, while it recorded 9 ind/m2 in pond II. In October, after pond II rehabilitation, the density was inversely proportional to July, and the highest density was found in pond I at 10 ind/m2, while pond II measured 9 ind/m2. After rehabilitation, the index value H’ decreased in pond I and pond II from 2.82 and 2.98 to 2.52 and 2.68, respectively. The mangrove density was 887 ind/ha in pond I and 686 ind/ha in pond II. The substrate in both ponds was clay. Nitrate concentration values ​​in the substrate in both ponds ranged from 0.27% to 0.29%, phosphate recorded a percentage of 0.07–0.09%, and C-organic ranged from 3.00% to 5.72%. The water's physicochemical parameters and the type and content of the substrate were still suitable for mollusk life.

Carbon sources and trophic levels in the food web of the largest mangrove reserve of China

Zhanjiang Mangrove National Nature Reserve (ZMNNR) is the largest mangrove natural reserve in China. We conducted the first comprehensive isotope study on the ZMNNR. Primary producers, including mangroves, grasses, microphytobenthos (MPB), etc. formed the lowest trophic level. Gastropods and bivalves, crustaceans and carnivorous fish were on the 2nd, 3rd and 4th trophic levels, respectively. In Zhanjiang tidal estuary, mangroves contributed about 1/3 of the carbon sources for consumers, substantially smaller than those in swamps and lagoons, but higher than those in river delta mangroves. The major carbon sources to the food web shifted from particulate organic matter (POM), consisting of detritus of mangrove leaves and phytoplankton, perennial grasses and mangrove leaves in the high tide zone to invasive Spartina alterniflora, POM and mangrove leaves in the low tide mudflat. Insignificant contributions of MPB were due to restricted light penetration by the dense mangroves in the high tide zone, and prolonged submersion and sediment resuspension in the low tide mudflat. Aquaculture effluents caused substantially higher δ15N values of all primary producers and consumers in the ZMNNR. In addition, high nutrient content and N/P ratios in aquatic effluents might allow cyanobacteria in MPB to be outcompeted by other fast growing microorganisms. Aquaculture effluents might also contribute to shortened trophic levels and promotion of the dominance of resistant species in the ZMNNR. We call for a sustainable development strategy to conserve the valuable ecosystem in the ZMNNR.

Heavy metal pollution status and deposition history of mangrove sediments in Zhanjiang Bay, China

Mangroves have high ecological service value and play an important role in achieving carbon neutrality. However, the ecological services provided by mangroves are gradually declining due to the threat of various pollutants, especially heavy metal (HM) pollution. Researching the status and history of heavy metals (HMs) in mangrove sediments improves understanding of how mangroves can be protected. We studied the Zhanjiang Bay mangroves, which is an important part of the Zhanjiang Mangrove National Nature Reserve, and is greatly affected by human activities, as an example. We analyzed the pollution levels and deposition process of HMs and their influencing factors. In the mangrove surface sediments of Zhanjiang Bay, Pb, Cr, and Co were slightly to moderate enriched and Cu was moderate-heavy enriched. Zn and Hg showed moderate-heavy enrichment and heavy enrichment, respectively. Cu, Zn, Hg, and Co were 1.5, 1.88, 2.66, and 1.27 times the local background, respectively. Cu, Zn, and Hg mainly originated from anthropogenic sources, and Co may have derived from natural sources. The HM data of mangrove sedimentary cores in Zhanjiang Bay were obtained for the first time; high HM content appeared in the deep layer of the cores but not in the mangrove surface sediments. Both cores were well documented for the effects of natural and anthropogenic factors on the deposition process of HMs. Among them, the high enrichment of Hg in 1909–1921 may be closely related to human activities rather than natural formation. Before 1954, dense mangroves favored the accumulation and gradual increase of HMs. The intense human activity in 1945–1963 during the period of economic construction and reclamation of the Nansan Island Engineering led to significant increases in Cu, Zn, Pb, Cr, and Co, which reached their highest values in more than one hundred years. After 1963, anthropic factors such as deforestation and conversion to aquaculture sharply reduced mangrove area. Reclamation engineering enhanced tidal erosion. Natural factors such as precipitation, storm surge, sea-level rise, and high tides have accelerated the erosion and dilution of mangrove sediments in Zhanjiang Bay. These factors have led to the gradual reduction of HM content in sedimentary cores.