Mangrove Forest Area Research Articles

Prediction on the changes in potential suitable areas for mangroves along the coast of Guangxi and the threat from Spartina alterniflora invasion.

As one of the important blue carbon pools in tropical and subtropical intertidal zones, mangroves are widely distributed along the coast of Guangxi in China. To deeply explore the variations of potential suitable habitats for mangroves in China under the background of climate change, based on remote sensing interpretation data of coastal wetlands in Guangxi, global marine environment and bioclimatic environment data in 2021, we constructed a maximum entropy habitat distribution model to simulate the spatial distribution of potential suitable areas for mangroves and the invasive species, Spartina alterniflora, along the coast of Guangxi, and predicted the patterns under extreme climate change scenarios (SSP5-8.5). The results showed that the interpreted area of mangrove forests along the coastline of Guangxi was 9136.7 hm2 in 2021, while the predicted area of potential suitable habitat area was 55955.9 hm2. Current distribution area of mangroves had basically covered its potential high suitability area and nearly 10% of the moderate suitability area. The current area of S. alterniflora was 1320.4 hm2, and the predicted area of potential high suitability area was twice of current area, indicating that there was still a large proportion of high suitability area that was not occupied by S. alterniflora. The most important environmental factors driving the distribution of potential habitats in mangroves were offshore Euclidean distance (62.2%), terrain deviation index (8.7%), average sea surface temperature in the hottest season (6.1%), and seabed terrain elevation (5.6%). The contribution of geographical conditions on mangrove distribution was predominant. Under the climate change scenario (SSP5-8.5), potential suitable area for mangroves would increase by 5.3%, while that for S. alterniflora would decrease by 3.1%. The overlapping proportion of the potential suitable area for mangroves and S. alterniflora was similar under current and SSP5-8.5 scenarios, being 15.2% and 14.5%, respectively. In the future, it is necessary to strengthen the protection and ecological restoration of mangroves along the coast of Guangxi and there is great challenge for preventing further invasion of S. alterniflora.

The Impact of Mangrove Forest Management on the Community in Poton Bako Hamlet, Jerowaru Village, East Lombok Regency

This research aims to: determine Mangrove Forest Management Patterns and the Impact on the Community in Poton Bako Hamlet, Jerowaru Village, East Lombok Regency. This research applies a qualitative approach with a case study method. The data collection techniques applied in this research are interviews, observation and documentation. The data analysis techniques in this research are data reduction, data presentation and drawing conclusions. The results of the research explain that (1) Mangrove Forest Conservation Pattern in Poton Hamlet, Jerowarau Village, namely the Mangrove Ecotourism Development Pattern (managers together with the community clean the mangrove forest from rubbish that has accumulated in the mangrove forest area to be developed into mangrove tourism), Mangrove Ecosystem Rehabilitation Pattern (manager creating a small-scale nursery area to create a stock of mangrove seeds for replanting), Mangrove Ecosystem Conservation Pattern (the management forms Pokmaswas members with the aim of acting as supervisors to prevent illegal felling of mangrove trees). (2) The impact of managing the mangrove forest for the community in Poton Bako hamlet is a positive impact (creating new jobs for the people of Poton Bako hamlet; increasing the economic income of the community by managing the mangrove forest into a tourist spot and a place to sell SME products such as mangrove coffee, mini-boats/ boats and clothes typical of Bale Mangrove tourism; catches of Poton Bako hamlet fishermen have increased and if the weather is not conducive to going to sea, fishing communities can look for shrimp, fish and crabs in the mangrove forest area; the community has received education and increased public awareness to protect the mangrove forest area. ; the coastal area of Poton Bako hamlet is protected from abrasion and prevents sea water intrusion onto land

Identification of Suitable Mangrove Distribution Areas and Estimation of Carbon Stocks for Mangrove Protection and Restoration Action Plan in China

Mangrove forests are significant blue carbon pools on the Earth with strong carbon sequestration capacity and play an important role in combating climate change. To improve the capacity of regional carbon sinks, China has implemented a Special Action Plan for Mangrove Protection and Restoration (2020–2025). In this context, based on the MaxEnt model, this study analyzed the important environmental factors affecting the distribution of mangrove forests, combined with the planning objectives and carbon density parameters of different regions; assessed the habitat suitability areas of China’s mangrove forests; and predicted their future carbon stock potential. The results showed the following: (1) Elevation was the most important factor affecting the overall distribution of mangrove forests in China, and the optimal elevation of mangrove distribution was 0.52 m. (2) The most suitable areas of mangrove forests in China were mainly distributed in Hainan, Guangxi, and Guangdong, which had great potential for carbon stock. Danzhou Bay and Hongpai Harbor in Hainan, Lianzhou Bay in Guangxi, and the Huangmao Sea in Guangdong are potential areas for habitat suitability but are not yet under high levels of protection. (3) Achieving the goals of this action plan was expected to increase carbon stocks by 4.13 Tg C. Other suitable areas not included in this plan could still increase carbon stocks by 7.99 Tg C in the long term. The study could provide a scientific basis for siting mangrove restoration areas and developing efficient management policies.

Population dynamics of mud clam Geloina expansa (Mousson, 1849) in degraded mangrove area at Kendari Bay, Indonesia

Abstract. Bahtiar B, Kasim M, Hati YIP, Ishak E. 2024. Population dynamics of mud clam Geloina expansa (Mousson, 1849) in degraded mangrove area at Kendari Bay, Indonesia. Biodiversitas 25: 616-623. Mud clams, Geloina expansa (Mousson, 1849), locally known as kalandue, are bivalves living in mangrove forests. These mud clams are currently experiencing ecological pressure, and are susceptible to the degradation of mangrove areas and the exploitation of the clams. This research was conducted in the mangrove forests of Kendari Bay for a year, from November 2016 to October 2017. Geloina expansa samples were collected throughout the mangrove forest area, and the water temperature was measured simultaneously with G. expansa sampling. The width of G. expansa shell was measured using a caliper. Population structure, growth, mortality, and exploitation rate data were analyzed using the Bhattacharya method, the von Bertalanffy inverse function, the width converted catch curve, and Pauly's empirical formula, all accommodated in the FiSAT II program version 3.0. The results showed that the G. expansa population was spread out from two and three-size groups, i.e., juvenile, adult, and old-size groups, dominated by the older group. Geloina expansa growth model follows the Lt = 10.08-(10.08-0.025) e-0.6t, which generally consists of 1.5-2.5 years of maturity. The total mortality (Z) of G. expansa was 2.26, in which the highest contributing factor was natural mortality (M) as opposed to fishing mortality (F), with values of M = 1.72 and F = 0.56. Thus, the exploitation rate (E) was within the low category, with a value of 0.24.

Monitoring Mangrove Forest Degradation in Mangrove Nature Tourism Park Angke Kapuk, North Jakarta, Indonesia Using NDVI

Mangrove forests in Angke Kapuk, North Jakarta, are integral parts of the coastal ecosystem and play important roles in supporting environmental sustainability. One component of the Angke Kapuk Mangrove Forest is the Mangrove Nature Tourism Park (MNTP), Angke Kapuk, covering an area of 99.82 hectares. This study aims to analyze mangrove forest degradation in Angke Kapuk Nature Reserve using the Normalized Difference Vegetation Index (NDVI, which allows for mapping mangrove vegetation density and monitoring changes in the vegetation density over time. The objective of this study is to determine the degradation of mangrove forests from 2018 to 2023 using the NDVI derived from Landsat 8 and Landsat 9 satellite imagery. The findings of this study showed a change of 13.16 hectares in forested areas between 2018 and 2023, suggesting forest degradation. Accuracy assessment resulted in %80 overall accuracy with a kappa coefficient of % 76.2. Based on the literature, our results are similar to the acceptable level of accuracy, which is considered to be above %80. Monitoring mangrove forest areas can serve as a preventive measure to address the issue of mangrove forest degradation. These results underscore the necessity of sustainable forestry monitoring efforts in the MNTP area, as it contributes significantly to providing ecosystem services and maintaining environmental sustainability.

Karakteristik Polen pada Spesies Mangrove di Kawasan Hutan Mangrove Batu Lumbang, Denpasar, Bali

The diversity of mangrove species in an area can be observed through morphological structure, anatomy, as well as palynology. Palynology is a study of pollen that frequently used as a reference to support data in identifying mangrove species. Mangrove areas in Bali have patchy distribution, one of which can be found in the Batu Lumbang area. Batu Lumbang is a mangrove area that is part of the Ngurah Rai Forest Park. Observation of the micromorphological characteristics of pollen in the Batu Lumbang mangrove forest area was carried out through the acetolysis method with modification. Eleven mangrove species were sampled, comprised of Aegiceras corniculatum, Avicennia marina, Bruguiera gymnorhiza, Ceriops tagal, Exoecaria agallocha, Lumnitzera racemosa, Rhizophora apiculata, Rhizophora mucronata, Sonneratia alba, Sonneratia caseolaris, and Xylocarpus granatum. The results of observations on pollen from eleven species of mangroves show similarities of pollennits, monads. In addition, other pollen characters such as aperture type, pollen shape, and pollen size categories found vary among the samples observed. These characters can also group several species that have the same family or genus. In turns, these can be used as diagnostic character to distinguish one species with another.

Blue Waqf Framework for Blue Forest Sustainability: A Conceptual Framework

Blue forests are areas that protect the coastline from flooding and erosion. They harbor wildlife and provide a sustainable livelihood for communities. One of the blue forest types is mangrove forest. Indonesia has the most expansive mangrove forest area in Southeast Asia, but nearly 25% has been deforested. Maintaining the sustainability of mangrove forests is one of the sustainable development goals (SDG) 14. Therefore, to achieve this goal, financing is needed to support the needs in maintaining the sustainability of mangrove forests. This paper is a conceptual framework that provides an Islamic social finance-based funding model for the blue forest sector. This program is called Blue Waqf. In order to implement this program, Indonesian Waqf Board and registered nazir are needed as the program’s coordinators. In addition, a colossal campaign needs to be conducted. The involvement of the surrounding community as a social adaptor is also vital. Last, waqf management through blue waqf requires protection from takaful/project guarantees. It has to be done to minimize the economy. The impact will be sustainable for the economy, society, and the environment. The profits obtained from blue waqf will be distributed to beneficiaries.
 Keywords: Blue Waqf, sustainable, Blue Forest, conceptual framework

Analysis Of The Mangrove Structure In The Dong Rui Commune Based On Multispectral Unmanned Aerial Vehicle Image Data

Mangroves are one of the most important types of wetlands in coastal areas and perform many different functions. Assessing the structure and function of mangroves is a premise for the management, monitoring and development of this most diverse and vulnerable ecosystem. In this study, the unmanned aerial vehicle (UAV) Phantom 4 Multispectral was used to analyse the structure of a mangrove forest area of approximately 50 hectares in Dong Rui commune, Tien Yen district, Quang Ninh Province – one of the most diverse wetland ecosystems in northern Vietnam. Based on the visual classification method combined with the results of field taxonomic sampling, a mangrove tree classification map was established for UAV with three species, Bruguiera gymnorrhiza, Rhizophora stylosa, and Kandelia obovata, achieving an overall accuracy = 86.28%, corresponding to a Kappa coefficient =0.84. From the images obtained from the UAV, we estimated and developed maps and assessed the difference in tree height and four vegetation indices, including the normalized difference vegetation index (NDVI), green normalized difference vegetation index (GNDVI), enhanced vegetation index (EVI), and green chlorophyll index (GCI), for three mangrove plant species in the flying area. Bruguiera gymnorrhiza and Rhizophora stylosa reach an average height of 4 to 5 m and are distributed mainly in high tide areas. Meanwhile, Kandelia obovata has a lower height (ranging from 2 to 4 m), distributed in low-tide areas, near frequent flows. This study confirms the superiority of UAV with red edge and near-infrared wave bands in classifying and studying mangrove structures in small-scale areas.

Mangrove Dynamics Evaluation at Matang Mangrove Forest Reserved by Multi-temporal Satellite Imageries

Mangrove ecosystems support a wide range of terrestrial and marine organisms by offering sustenance, reproductive habitats, and nurturing environments. The Matang Mangrove Forest Reserve (MMFR), spanning over 40,000 ha, poses challenges in effectively managing and evaluating the entire area. Hence, remote sensing techniques are employed to effectively monitor and map the temporal fluctuations of land use and land cover occurring within mangrove forest areas. In this study, dynamics over nine (9) years (2011to 2020) of the mangrove ecosystem were evaluated using RapidEye 2011 and Landsat 8 (OLI) 2020 satellite imageries. Change detection was implemented using pixel-by-pixel modelling analysis. The present study revealed the conversion of mangrove area to waterbody at 4625.1 ha (16.7%), dryland forest at 1886.1 ha (6.8%), and oil palm plantations at 186.9 ha (0.7%). The area conversion was attributed to erosion, logging operations, the establishment of aquaculture facilities, and agricultural practices. Hence,the acquisition of data pertaining to the present condition of mangrove forest species, as well as the temporal fluctuations in the study area, holds significant importance for all stakeholders involved in the preservation of this ecosystem.

Spatio-temporal NDVI changes of mangrove forest in West Bangkalan using high resolution imagery

Mangrove play a crucial role in coastal ecosystem, both ecologically and economically. The phenomenon of land use change in coastal areas is a serious issue, especially for mangrove ecosystems. Currently there is one of the data with the High Resolution Imagery category that can be used as an analysis of coastal areas. High resolution data can provide detailed information on changes in coastal areas. The case study conducted in this analysis is on the west coast of Bangkalan Regency, precisely in Arosbaya District. The assessment carried out in this study is the analysis of temporal variations in the Normalize Different Vegetation Index (NDVI) value in mangrove forest areas using High Resolution satellite imagery. The data used is PlanetScope image with 3 m spatial resolution with 4 spectral bands from 2018-2023. The results of the analysis show that the average value of NDVI in the study area is 0.66 with a quite high value distribution in the western and eastern parts. The temporal standard deviation value of NDVI shows that some locations have high values, reaching 0.5 in some locations. Analysis of the trend of change shows that locations with high standard deviation values have a tendency to have increasing trend values in the north (>0.2 per year) and there is also a decreasing trend in the south (<-0.2 per year). After identification, areas with increasing (positive) NDVI trends are areas that have experienced mangrove rehabilitation in recent years. While in areas with a downward trend there is a change in land use that was previously a mangrove forest area into ponds.

Analysis of types, forms and abundance of microplastics in the mangrove forest area of pusong island, langsa city

Pollution of mangrove waters by microplastic particles is coastal plastic waste pollution which has become a major water pollution problem in developing countries. However, this pollution problem, both qualitatively and quantitatively, has not yet been discussed comprehensively. Therefore, it is necessary to analyse the level of microplastic presence and identify the types of microplastics of each size found in the water in the mangrove forest area of Langsa City-Aceh. The aim of this research is to analyse the presence, shape and dominance of microplastic particles in the mangrove waters of Langsa City. The research method was carried out by taking water and river sediment samples based on SNI 03-7016-2004 and the samples were the result of a combination of places (integrated samples). Separation of microplastics is carried out by filtering, destroying organic compounds, separating based on specific gravity and filtering using vacuum. Identification of the type, shape and abundance of microplastics is carried out using a microscope. The analysis results show that microplastics in water are generally of the fragment and fibre type with a density of between 7 - 13 particles per Liter with an average size of 200 µm.

Species Composition and Density in the Mangrove Forest Area of Sriminosari Village, Labuhan Maringgaika District, East Lampung Regency

Mangroves are mangrove species that can develop and grow in muddy tidal areas so that they can form a vegetation community. Mangroves have a unique adaptability, namely the ability to adapt to oxygen levels (O2) which is low causing the root system in mangroves to look like chicken claws and is included in the buffer type. The presence of mangrove forests has an important role in keeping the monitoring lip area from abrasion by sea waves so that it remains stable. The purpose of this study was to determine the species composition and density in the mangrove forest area of Sriminosari Village, Labuhan Maringgai District, East Lampung Regency. Based on the results of research that has been conducted in the mangrove forest area of Sriminosari Village, it can be concluded that the vegetation found in the mangrove forest area of Sriminosari Village contains 2 mangrove tribes. The relative density value of mangroves in the village of Sriminosari on speciesAvicennia marinawith a percentage of 100%. As for the species apiculata has a percentage of 24.4%. Based on H’total calculation of 1.2, it means that the mangrove forest of Sriminosari Village belongs to the medium category from the calculation of the Shannon-Wiener index

Spatial and temporal study of estimating carbon stocks distribution of mangrove forest in coastal area of Teluknaga, Tangerang

Coastal mangrove forests play a crucial role in balancing carbon emissions in the atmosphere as they are a significant carbon store. Previous studies have shown that mangroves can absorb carbon four times more efficiently than terrestrial tropical forests. Unfortunately, the massive development and land use changes in Teluknaga District's coastal areas threaten these ecosystems' existence. To address this concern, efforts are being made to increase conservation, including estimating carbon stock. The aim of this study is to analyze the spatial distribution of biomass and carbon stock of mangrove forests in Teluknaga between 2016-2022 based on vegetation indices such as ARVI, EVI, and SAVI. Sentinel-2 was calculated into ARVI, EVI, and SAVI vegetation indices to model biomass. Statistical correlation analysis was also used to determine the best vegetation index to model biomass in the coastal area of Teluknaga District. This study found that the ARVI vegetation index had the best correlation (R = 0.60) for modeling biomass, with an RMSE value of 36.67 kg/pixel. Most mangrove forests in the coastal area of Teluknaga District showed an increase in biomass and carbon stock between 2016-2022, with significant growth in Muara and Lemo villages' mangrove forests, which is in line with an increase in the area and density of mangrove forests.

Healthy Index Level of Mangrove Forests around Sylvo-Ecotourism in Tanjungpiayu and Kabil, Batam Island

The existence of mangrove forests in several coastal areas of Batam Island is threatened by the development of settlements and ports as well as industrial activities. Environmental changes due to land clearing have an impact on the health of the surrounding mangrove forests. In fact, several mangrove forest areas in Batam City have the potential to be developed as mangrove sylvo-ecotourism areas. The decline in the health of mangrove forests around land conversion areas can be seen from the level of tree damage. Mangrove tree sampling was carried out in Tanjungpiayu Village and Kabil Village in Batam, Riau Islands Province. Sampling of tree stands using cluster plots. The tree health index is observed based on the percentage of damage locations, type and severity of tree damage. The research results showed that the mangroves around the sampling location were considered healthy even though there was light and moderate damage. The worst damage locations are on the leaves, roots and lower stem. The most types of damage were in other categories (submerged in red mud), damaged and discoloured leaves, termites, broken or dead roots and stems. The most severe levels occur around 10-20%, 30% and 90%. The health of the mangroves in the Tanjungpiayu and Kabil mangrove sylvo-ecotourism areas is still relatively good.

Estimation of Rhizophora mucronata carbon stock in Youtefa bay, Jayapura, Papua

Papua island has the largest mangrove forest area in Indonesia, reaching 1,350,600.00 Ha which accounts for half of the entire area of mangrove forests in Indonesia. One of the locations with a fairly extensive mangrove forest in the Jayapura area is in Youtefa Bay. Although mangroves have large environmental potential, local people use the forest as building materials, food, fishing tools, and medicines. Mangrove forests have an active role in maintaining global climate stability in the world, forest vegetation will fix CO2 through the process of photosynthesis. Mangrove forests per hectare can store up to four times more carbon than other tropical forests worldwide. This research aims to estimate the amount of carbon stock Rhizophora mucronata can store in mangrove forests in Youtefa Bay, particulary in Tobati, Enggros and Entrop Villages, Jayapura, Papua. The method used in this study was using Allometric Equations to estimate the biomass carbon from Rhizophora mucronata and compared to three different satellite imagery algorithms. The research results showed that the biomass of Rhizophora mucronata stands in Entrop Village was the highest and the lowest in Enggros Village. In addition, the results of measurements of carbon stocks in Tobati and Enggros Villages showed that the values were similar, only 0.23 kgC/m2 with carbon stocks in Entrop Village reaching 19.46 kgC/m2. Based on the results of measuring satellite imagery with three different algorithms, it was found that using the EVI algorithm produced the smallest Standard Error of Estimate, which was 1.63 kg C/m2. The estimated total carbon in Youtefa Bay is 213,424.69 kg C/m2.Keywords:AllometricCarbon StockRhizophora mucronataYoutefa Bay

Loss of carbon stock as an impact of anthropogenic activities in a protected mangrove forest

Abstract. Eddy S, Setiawan AA, Taufik M, Oktavia M, Utomo B, Milantara N. 2023. Loss of carbon stock as an impact of anthropogenic activities in a protected mangrove forest. Biodiversitas 24: 6493-6501. The significant anthropogenic activities within the mangrove forest, known as the Air Telang Protected Forest (ATPF) in the Banyuasin District, South Sumatra, Indonesia, have led to an alarming degradation, leaving only its primary mangrove forests, currently constituting approximately 26% of the total forest area. This study aims to analyze changes in land cover, quantify carbon reserve loss due to CO2 emissions, and assess carbon sequestration in the ATPF over two periods: 1999-2010 and 2010-2023. Remote sensing data for 1999, 2010, and 2023 were utilized from Landsat imagery, employing ENVI and ArcGIS for land cover classification. Carbon density, CO2 emissions, and carbon sequestration were analysed using the Land Use Planning for Multiple Environmental Services (LUMENS) software. The research findings reveal an increase in the primary forest area in the first period (by almost a quarter); however, more than half of this area was lost in the second period. The secondary forest area consistently decreased over the two periods, while the open area experienced significant growth. Carbon stocks in 2010 exceeded those in 1999 due to an increase in the primary forest area, but by 2023, carbon stocks decreased significantly due to extensive land clearing. The second period witnessed the largest emissions, exceeding those of the previous period by five times. Carbon sequestration in the first period surpassed that in the second period by more than three times, with the most significant sequestration resulting from the growth of secondary mangrove forests into primary mangrove forests. The study highlights the necessity of restoration and conservation of mangrove forest areas in ATPF for sustenance of its natural function as a protected forest.

Green Waterfront City, Future Perspectives for Sustainable City in Tidal Flooding Prone Area at Northern Semarang

Due to their low topography and flat terrain, Semarang's northern coastal areas are vulnerable to tidal flooding. This paper explains the concept of Green Waterfront City for northern coastal areas of Semarang. The concepts include: the design of mangrove forest areas on Semarang's North Coast as a natural, eco-friendly barrier that withstands sea abrasion; the concept of an artificial embankment made of natural materials that collects sediment and turns into a dike to reduce sea abrasion; and amphibious housing, which is a versatile, light-colored, eco-friendly residential area. Should the concept be put into practice, it would create advantages in some aspects such as: a) Socially, people affected by the tidal floods on the north coast of Semarang will be provided with appropriate housing and permitted to go back to where they previously lived; b) Economy: Communities affected by tidal floods on Semarang's north coast will see an increase in their economic worth in the fishing and tourism industries through the introduction of Silvofishery; c) Environment: The development of Green Waterfront City for northern coastal areas of Semarang can mitigate the negative environmental effects of tidal flooding and sea abrasion.

Partisipasi Masyarakat dalam Penanaman Mangove untuk Meningkatkan Ekowisata di Kelurahan Klawalu Kota Sorong

Klawalu Mangrove Ecotourism, a mangrove forest area in Sorong City, Southwest Papua, has great potential as a significant tourist destination. Therefore, increasing community involvement in mangrove planting is very important to support ecotourism development. Ecotourism not only provides natural entertainment to tourists but also aims to enable tourists to actively participate in environmental conservation efforts. Apart from that, it is also hoped that tourists will gain a deep understanding of the complexity of the environment, forming an awareness of the importance of preserving the region, both now and in the future. This service aims to increase community participation in planting mangroves to improve ecotourism in Sorong City. With this service, it can increase public awareness of the importance of an educational, green, and clean environment and strengthen community initiatives to protect, maintain, and improve the function of the environment. So with mangrove ecotourism, the welfare of local communities can increase. Through the implementation of ecotourism, it is hoped that opportunities will be created for the growth of MSMEs.

Spatial variation and mechanism of the dissolved/particulate organic carbon partitioning of seawater adjacent to the mangrove in Zhangjiang Estuary

Mangrove is one of the most carbon-rich ecosystems in the world. Nevertheless, the understanding of organic carbon partitioning between dissolution and particle in the processes of mangrove outwelling is rather limited, flood–ebb samplings were conducted in January 2021 with 8 sampling sites covering the upper tidal boundary to the mouth in the Zhangjiang Estuary. Water samples were collected to analyze physicochemical properties, dissolved organic carbon (DOC) and particulate organic carbon (POC) contents, and their phase portioning were investigated to analyze the spatial variation between the two phases (dissolve and particle), and their influencing factors. The results showed: (1) DOC was the dominant content with the wide range of 0.48–3.29 mg·L−1, accounting for 77.6% on average; while POC contents were 0.17–1.86 mg·L−1, accounting for 22.4% on average. (2) Silt was dominant component in estuarine suspended sediment, accounting for 68.0% on average; clay accounted for 17.5% of the suspend sediment, and was mainly located in mangrove forest area; sand proportion was the lowest. (3) Both the closed Beijiang sluice and ponds effluents could significantly increase the water organic carbon content, but only ponds effluents changed the phase distribution of organic carbon. In natural processes, a significant positive correlation between particulate and dissolved organic carbon and dissolved oxygen (DO) in the upper estuary (r > 0.9), and a significant negative correlation between particulate and dissolved organic carbon and salinity in the lower estuary (r < −0.7) were observed. The study indicated that DOC was the dominant content, the phase partition coefficients were significantly increased due to the DOC content from pond effluents. In the natural processes, the autotrophic activities by microalgae in the upper estuary and the seawater mixed dilution followed with heterotrophic activities are the important influencing factors.

Philippine mangroves: species composition, characteristics, diversity, and present status

Through the years mangrove areas in the Philippines continued to decline due to human activities. This paper aims to present the status of the Philippine mangroves based on species composition, diversity, and mangrove forest area through manuals, books, and other local and international online resources. Results showed that there were 35 species of mangroves described in terms of their external features, substrate, and zone preference. Bohol had the most diverse mangrove ecosystem with 26–34 species. The most prevalent species were Avicennia, Sonneratia, and Rhizophora that grew in muddy substrates. Among the provinces, 18.52% had mangrove areas recognized as protected areas. Mangrove decline is attributed to the increase of brackish water culture ponds and the greatest decline occurred when shrimp culture boomed in the 1980s. Other causes are over exploitation, weak law enforcement, lack of manpower and resources, corruption, and poor management of mangrove areas and brackish water ponds. Along with this is the loss of flood control and coastal protection indicating increased susceptibility to climate change. Thus, reforestation and reversion of abandoned brackish water ponds are needed. Reforestation must ensure the suitability of mangrove species to the physical characteristics of the environment. Also, the government must actively spearhead the sustainable use of mangrove ecosystems.