Mangrove Communities Research Articles

Structure and Dominance of Species in Mangrove Forest on Kutai National Park, East Kalimantan, Indonesia

The Kutai National Park (KNP) which is located in East Kutai Regency on East Kalimantan Province is endowed with numerous pristine of mangrove forest. However, related information to the species composition and diversity of KNP mangrove is still scanty. Twenty-one of mangrove species were recorded using the quadratic transects survey method (total plot area of 1.7 ha). Main species of mangrove communities were Avicennia lanata, A. marina, Bruguiera gymnorrhysa, B sexangular, Ceriops tagal, Rhizophora apiculata, R. mucronata and Sonneratia Alba. Mangrove density was recorded reached as 1,699 trees ha-1, saplings of 4,395 ha-1 and seedlings 25,348 ha-1. Significant tree density was found in Pandan Bay Estuary. While in the Lombok Bay and the Kaba Bay significant for sapling and seedling categories. Importance value index of mangrove species in the three study locations for three growth categories (tree, sapling and seedling) showed significant differences (p-value> α0.05). Mangrove stand at three study locations has almost the same characteristics. The species diversity and evenness index has shown the same distribution pattern. The findings of this study suggest that KNP mangrove forest stand is not heavily damaged even though there is a lot of human activity. This mangrove could be managed and conserved for multi-sectoral purposes such as ecotourism, research, biodiversity and education rather than solely as a Nature Conservation Area.

Aboveground mangrove biomass estimation in Beibu Gulf using machine learning and UAV remote sensing

On the basis of canopy height variables, vegetation index, texture index, and laser point cloud index measured with unmanned aerial vehicle (UAV) low altitude remote sensing, we used eight machine learning (ML) models to estimate the aboveground biomass of different species of mangroves in Beibu Gulf and compared the accuracy of different ML models for these estimations. The main species of typical mangrove communities in Kangxiling were Aegiceras corniculata and Sonneratia apetala. The trunks of Sonneratia apetala were thicker, with an average height of 11.82 m, whereas Aegiceras corniculata trees were shorter, with an average height of 2.58 m. The XGBoost regressor (XGBR) model had the highest accuracy in estimating mangrove aboveground biomass (R2 = 0.8319, RMSE = 22.7638 Mg/ha), followed by the random forest regressor model (R2 = 0.7887, RMSE = 25.5193 Mg/ha). Support vector regression, decision tree regressor, and extra trees regressor had poor fitting effects. Mangrove texture index ranked first in importance for the model, followed by the mangrove laser point cloud height index, and the laser point cloud intensity index performed the worst in the model. Mangrove aboveground biomass in the study area is high in the north and low in the south, ranging from 38.23 to 171.80 Mg/ha, with an average value of 94.37 Mg/ha. Generally, the XGBR method can better estimate the aboveground biomass of mangroves based on the measured mangrove plot data and UAV low-altitude remote sensing data.

Macroecological patterns of forest structure and allometric scaling in mangrove forests

AbstractAimMangrove wetlands span broad geographical gradients, resulting in functionally diverse tree communities. We asked whether latitudinal variation, allometric scaling relationships and species composition influence mangrove forest structure and biomass allocation across biogeographical regions and distinct coastal morphologies.LocationGlobal.Time periodPresent.Major taxa studiedMangrove ecosystems.MethodsWe built the largest field‐based dataset on mangrove forest structure and biomass to date (c. 2,800 plots from 67 countries) to address macroecological questions pertaining to structural and functional diversity of mangroves spanning biogeographical and coastal morphology gradients. We used frequentist inference statistics and machine learning models to determine environmental drivers that control biomass allocation within and across mangrove communities globally.ResultsAllometric scaling relationships and forest structural complexity were consistent across biogeographical and coastal morphology gradients, suggesting that mangrove biomass is controlled by regional forcings rather than by latitude or species composition. For instance, nearly 40% of the global variation in biomass was explained by regional climate and hydroperiod, revealing nonlinear thresholds that control biomass accumulation across broad geographical gradients. Furthermore, we found that ecosystem‐level carbon stocks (average 401 ± 48 MgC/ha, covering biomass and the top 1 m of soil) varied little across diverse coastal morphologies, reflecting regional bottom‐up geomorphic controls that shape global patterns in mangrove biomass apportioning.Main conclusionsOur findings reconcile views of wetland and terrestrial forest macroecology. Similarities in stand structural complexity and cross‐site size–density relationships across multiscale environmental gradients show that resource allocation in mangrove ecosystems is independent of tree size and invariant to species composition or latitude. Mangroves follow a universal fractal‐based scaling relationship that describes biomass allocation for several other terrestrial tree‐dominated communities. Understanding how mangroves adhere to these universal allometric rules can improve our ability to account for biomass apportioning and carbon stocks in response to broad geographical gradients.

Efficiency in heavy metal purge in crustaceans during the ecdysis

An abundant population of Ucides cordatus swamp crabs is present at Lameirao Ecological Station (Brazil), a tropical ecosystem man-made with discharges of domestic, industrial and agricultural pollutants. Concentrations of heavy metals in water, sediment and muscle tissues, gills, hepatopancreas and exoskeleton present in crustaceans were analyzed. The results showed variations in the concentrations of all metals according to precipitation, tide and physicochemical factors. This fact possibly influenced the results of bioconcentration (BFC > 1), indicating a tendency of bioaccumulation according to environmental conditions. We also found a high accumulation of metals in female specimens. However, regardless of gender, we found a reduction in metal concentrations in all tissues analyzed during the period of ecdysis. In this study, we highlight the ecological role of U. cordatus in mangrove ecosystems and its importance in transferring pollutants to the upper trophic levels of the mangrove community, and even to man.

STRUKTUR KOMUNITAS VEGETASI MANGROVE DI PESISIR UTARA PULAU MENDANAU DAN PULAU BATU DINDING, KECAMATAN SELAT NASIK KABUPATEN BELITUNG

Mendanau Island and Batu Dinding Island are part of small island groups that have a high diversity and density of mangroves. Based on administratively, Mendanau Island is located in the coastal area of Simpang Pesak District, Belitung Regency, which consist of one large island (Mendanau Island) and 1 small island (Batu Dinding Island). The lack of data about potential, diversity, and community structure of mangroves on the north coast of Mendanau Island and Batu Dinding Island, therefore this research is needed as a database for planning, sustainability management of mangroves at the coastal area and small island. The data of mangrove vegetation was taken by purposive sampling method, with using line transect plot (LTP). Ilustration of sampling design is each line transect have 3 plot / kuadratic transect sized 10 m x 10 m (capling), 5 m x 5m (sapling), 1m x 1 m (seedling). The result showed that there are 12 (twelve) mangrove species were found: jenis S. alba, R. apiculata, R. stylosa, R. mucronata, B. gymnorhiza, X. granatum, L. littorea. S. hydrophyllacea, S. taccada, H. tiliaceus, Pandanus, dan I. pes-caprae. Mangrove community structure and mangrove condition on the North Coast of Mendanau Island, at several observation stations, was damaged (poor conditions), while the status of the mangrove conditions on Pulau Batu Dinding was still relatively good

Linking modern-day relicts to a Miocene mangrove community of western Amazonia

The Amazon drainage basin is extremely biodiverse, yet the origins of this diversification remain much debated. One of the possible drivers of plant diversity are the marine incursions that reached Amazonia during the Miocene and connected western Amazonia with the Caribbean. In the Miocene, large parts of western Amazonia were covered by extensive wetlands that, during high eustatic episodes, were episodically colonised by coastal taxa such as mangroves. In this paper, we hypothesise that some of these mangrove community taxa could adapt to freshwater conditions enriching the modern plant composition of the Amazon drainage basin. To assess the past plant composition in the basin, we statistically analyse the palynological composition of two Miocene sections from western Amazonia that were especially rich in presumed mangrove pollen (Zonocostites ramonae). We identify the pollen taxa that coexisted with this community using clustering methods supported by Kendall’s W coefficient concordance analysis. Our results suggest that at least fourteen taxa are closely associated with Zonocostites ramonae (Cricotriporites guianensis, Deltoidospora adriennis, Psilabrevitricolporites devriesii, Psiladiporites redundantis, Psilamonocolpites amazonicus, P. rinconii, Psilatricolporites crassoexinatus, P. labiatus, P. operculatus, Psilatriporites corstanjei, Retitricolporites kaarsii, Rhoipites guianensis, Rhoipites hispidus, and Tetracolporopollenites transversalis). We also illustrate the pollen of this fossil mangrove, and some of its associated fossil taxa, using light microscopy (LM) and scanning electron microscopy (SEM), and we compare them with potential nearest living relatives (NLR). We found that pollen of the modern mangrove Rhizophora mangle is the NLR of Zonocostites ramonae. Of the three associated taxa, the best analogy is between Psilabrevitricolporites devriesii and Humiria balsamifera, the latter a taxon best known from the coastal restinga vegetation in Brazil and Surinam. Tentatively, we assign Forsteronia spp. as NLR for Cricotriporites guianensis, and we propose Euterpe sp. for Psilamonocolpites rinconii (but also Oenocarpus, Hyospathe, Prestoea, and Sabinaria are affine). Based on this study we propose that, at least for some fossil taxa of the Miocene mangrove environment, there are still NLR or relict species that occur in inland Amazonia and along the South American coastline. We thus conclude that the Amazonian flora, like riverine fauna such as the pink river dolphin (Inia) and selected fish taxa, carry an imprint of the Miocene coastal communities.

Effects of Spartina alterniflora Invasion on Soil Microbial Community Structure and Ecological Functions.

It has been reported that the invasion of Spartina alterniflora changed the soil microbial community in the mangrove ecosystem in China, especially the bacterial community, although the response of soil fungal communities and soil microbial ecological functions to the invasion of Spartina alterniflora remains unclear. In this study, we selected three different communities (i.e., Spartina alterniflora community (SC), Spartina alterniflora–mangrove mixed community (TC), and mangrove community (MC)) in the Zhangjiangkou Mangrove Nature Reserve in China. High-throughput sequencing technology was used to analyze the impact of Spartina alterniflora invasion on mangrove soil microbial communities. Our results indicate that the invasion of Spartina alterniflora does not cause significant changes in microbial diversity, but it can alter the community structure of soil bacteria. The results of the LEfSe (LDA Effect Size) analysis show that the relative abundance of some bacterial taxa is not significantly different between the MC and SC communities, but different changes have occurred during the invasion process (i.e., TC community). Different from the results of the bacterial community, the invasion of Spartina alterniflora only cause a significant increase in few fungal taxa during the invasion process, and these taxa are at some lower levels (such as family, genus, and species) and classified into the phylum Ascomycota. Although the invasion of Spartina alterniflora changes the taxa with certain ecological functions, it may not change the potential ecological functions of soil microorganisms (i.e., the potential metabolic pathways of bacteria, nutritional patterns, and fungal associations). In general, the invasion of Spartina alterniflora changes the community structure of soil microorganisms, but it may not affect the potential ecological functions of soil microorganisms.

The coastal community perspective of the mangrove ecosystem management in Karawang Regency, West Java, Indonesia

The development of coastal areas is growing rapidly in line with the high population growth that will threaten the continuity of coastal areas and ecosystems. Mangrove area located in the coastal area of Karawang Regency becomes an ecologically challenged area that greatly affects its sustainability. This study aims to examine mangrove ecosystems and community perspectives on the management of the mangrove ecosystems continuously and sustainably. The method used was a survey study at Nine Districts in Karawang Regency using the descriptive method with case study and perspective analysis on ten categories. Data were collected through interviews, observation and supported by secondary data. The description of this study was focused on mangrove ecosystem condition and community perspective in mangrove area management in coastal district Karawang. Data analysis used was a descriptive qualitative approach based on average with scales. The analysis results showed that most of the coastal communities in Karawang Regency strongly agree that; 1) The mangrove area in Karawang Regency is currently necessary/important to be managed to be sustainable, 2) The form of mangrove area management should involve all the local people, 3) There needs to be cooperation between the government and the local community in mangrove area management activities.

Monitoring Mangrove Forest Degradation and Regeneration: Landsat Time Series Analysis of Moisture and Vegetation Indices at Rabigh Lagoon, Red Sea

Rabigh Lagoon, located on the eastern coast of the Red Sea, is an ecologically rich zone in Saudi Arabia, providing habitat to Avicennia marina mangrove trees. The environmental quality of the lagoon has been decaying since the 1990s mainly from sedimentation, road construction, and camel grazing. However, because of remedial measures, the mangrove communities have shown some degree of restoration. This study aims to monitor mangrove health of Rabigh Lagoon during the time it was under stress from road construction and after the road was demolished. For this purpose, time series of EVI (Enhanced Vegetation Index), MSAVI (Modified, Soil-Adjusted Vegetation Index), NDVI (Normalized Difference Vegetation Index), and NDMI (Normalized Difference Moisture Index) have been used as a proxy to plant biomass and indicator of forest disturbance and recovery. Long-term trend patterns, through linear, least square regression, were estimated using 30 m annual Landsat surface-reflectance-derived indices from 1986 to 2019. The outcome of this study showed (1) a positive trend over most of the study region during the evaluation period; (2) most trend slopes were gradual and weakly positive, implying subtle changes as opposed to abrupt changes; (3) all four indices divided the times series into three phases: degraded mangroves, slow recovery, and regenerated mangroves; (4) MSAVI performed best in capturing various trend patterns related to the greenness of vegetation; and (5) NDMI better identified forest disturbance and recovery in terms of water stress. Validating observed patterns using only the regression slope proved to be a challenge. Therefore, water quality parameters such as salinity, pH/dissolved oxygen should also be investigated to explain the calculated trends.

Mangrove Community Structure Morowali District, Central Sulawesi Province, Case In Maratape Village, Lafeu Village, And Labota Village

The research purpose aims at analyzing the structure of the existing mangrove communities along the coastal area of Morowali District, Central Sulawesi Province. The sampling was taken from three villages, i.e. Maratape Village, Lafeu Village, and Labota Village. This research used the quadrant line transect method. The analysis and description were made after the method had been conducted. The composition of mangrove species found in this research was 3 (three) types, i.e. Rhizophora apiculata, Sonneratia alba, and Rhizophora stylosa. Of the three species the research finds, the dominant ones are Rhizophora apiculata and Sonneartia alba. The highest species density values were found at Station 1 (M01), i.e. R. apiculata. The frequency value had the highest value found at Station 2 (M02), i.e. R. apiculata type, and the highest relative frequency was R. apiculata. The highest closing value, i.e. S. albater type could be found at Station 2 (M02). The importance value index of Rhizophora apiculata type at the Station 1 (M01) had the highest value and followed in Station 3 (M03), i.e. Sonneratiaalba type, the lowest INP analysis in all stations was Rhizophora type stylosa. The dominant mangrove in 3 (three) Morowali District Stations were Rhizophora apiculata and Silneratia alba types. Based on the research results conducted on the structure of mangrove ecosystem communities in Morowali District, Central Sulawesi Province (Maratape Village Menui Kepulauan Sub-District (station 1), Lafeu Village Bungku Pesisir Sub-District (station 2) and Labota Village Bungku Tengah Sub-District (station 3) are definitely classified as natural and have not experienced significant degradationKeywords: Community Structure, Mangrove, Morowali, Central SulawesiAbstrakKajian ini bertujuan untuk menganalisis struktur komunitas mangrove yang ada disepanjang pesisir Kabupaten Morowali Provinsi Sulawesi Tengah. Sampling dilakukan pada tiga desa yaitu Desa Maratape, Desa Lafeu, dan Desa Labota. Kajian ini menggunakan metode line transek kuadaran dilanjutkan dengan analisissnya, kemudian dideskripsikan. Komposisi jenis mangrove yang ditemukan sebanyak 3 (tiga) jenis yaitu Rhizophora apiculata, Sonneratia alba, dan Rhizophora stylosa. Dari ketiga jenis yang ditemukan yang dominan yaitu Rhizophora apiculata dan Sonneartia alba. Nilai kerapatan jenis tertinggi terdapat di Stasiun 1 (M01) yaitu R. apiculata yaitu. Nilai frekuensi memiliki nilai tertinggi terdapat di Stasiun 2 (M02) yaitu jenis R. apiculata, dan frekuensi relatif tertinggi R. apiculata. Nilai penutupan tertinggi yaitu jenis S. alba terdapat di Stasiun 2 (M02) Indeks nilai penting jenis Rhizophora apiculata di Stasiun 1 (M01) memiliki nilai tertinggi dan di ikuti Stasiun 3 (M03) jenis Sonneratia alba, analisis INP yang terendah dari semua stasiun yaitu jenis Rhizophora stylosa. Mangrove dominan di 3 (tiga) stasiun Kabupaten Morowali adalah dari jenis Rhizophora apiculata dan Sonneratia alba. Berdasarkan hasil penelitian yang telah dilakukan terhadap struktur komunitas ekosistem mangrove di Kabupaten Morowali Provinsi Sulawesi Tengah (Desa Maratape Kecamatan Menui Kepulauan (stasiun 1), Desa Lafeu Kecamatan Bungku Pesisir (stasiun 2) dan Desa Labota Kecamatan Bungku Tengah (stasiun 3) masih tergolong alami dan belum mengalami degradasi yang berarti.Kata kunci : Struktur komunitas; Mangrove; Morowali; Sulawesi Tengah

Fine root biomass and its contribution to the mangrove communities in three saline zones of Sundarbans, Bangladesh

Globally, sea levels are rising due to climate change which would influence the salinity levels in mangroves. In the framework of this study, we focused on the influence of salinity and differences of forest structure on the fine root biomass (FRB) and carbon stocks in the Sundarbans mangrove forest, Bangladesh. Also, the relationships FRB to different stand structural parameters were investigated using the data obtained from 50 sample plots (100 sq. m each) in different salinity zones in Sundarbans. Four random soil samples (30 cm in length) were taken within study plots, which were further divided into 10 cm, 20 cm, and 30 cm to identify the most active soil layer for FRB stocks. Results suggest differences in forest structural parameters and diversity indices with salinity changes in different saline zones. The low and medium saline zone is dominated by Heriteira fomes, while Excoecaria agallocha dominates the high saline zone. The carbon stocks (Mg C ha−1) in Sundarbans show a significant decrease with increasing salinity in different saline zones, e.g. oligohaline (252 ± 60.2), mesohaline (199 ± 37.7), and polyhaline (171 ± 20.0) zone. FRB carbon (Mg C ha−1) allocation in different saline zones also followed a decreasing order, such as oligohaline (12.8), mesohaline (7.9), and polyhaline (7.3). Fine root biomass showed a decreasing trend with increasing soil depth, where the differences, however, were not significant (p > 0.05) among the soil layers. Our results provide evidence on FRB variations in Sundarbans, which has implications on the mangrove species conservation and management. The mature stands at different saline zones of Sundarbans mangrove forest, Bangladesh has a high fine root biomass, which is valuable for mangrove restoration and the studied species plantation in the shore line or coastal area which can help to decrease the erosion effects of tidal inundation.

Probabilistic Mangrove Species Mapping with Multiple-Source Remote-Sensing Datasets Using Label Distribution Learning in Xuan Thuy National Park, Vietnam

Mangrove forests play an important role in maintaining water quality, mitigating climate change impacts, and providing a wide range of ecosystem services. Effective identification of mangrove species using remote-sensing images remains a challenge. The combinations of multi-source remote-sensing datasets (with different spectral/spatial resolution) are beneficial to the improvement of mangrove tree species discrimination. In this paper, various combinations of remote-sensing datasets including Sentinel-1 dual-polarimetric synthetic aperture radar (SAR), Sentinel-2 multispectral, and Gaofen-3 full-polarimetric SAR data were used to classify the mangrove communities in Xuan Thuy National Park, Vietnam. The mixture of mangrove communities consisting of small and shrub mangrove patches is generally difficult to separate using low/medium spatial resolution. To alleviate this problem, we propose to use label distribution learning (LDL) to provide the probabilistic mapping of tree species, including Sonneratia caseolaris (SC), Kandelia obovata (KO), Aegiceras corniculatum (AC), Rhizophora stylosa (RS), and Avicennia marina (AM). The experimental results show that the best classification performance was achieved by an integration of Sentinel-2 and Gaofen-3 datasets, demonstrating that full-polarimetric Gaofen-3 data is superior to the dual-polarimetric Sentinel-1 data for mapping mangrove tree species in the tropics.

Drivers of bacterial diversity along a natural transect from freshwater to saline subtropical wetlands

Tropical coastal wetlands provide a range of ecosystem services that are closely associated with microbially-driven biogeochemical processes. Knowledge of the main players and their drivers in those processes can have huge implications on the carbon and nutrient fluxes in wetland soils, and thus on the ecosystems services we derive from them. Here, we collected surface (0–5 cm) and subsurface (20–25 cm) soil samples along a transect from forested freshwater wetlands, to saltmarsh, and mangroves. For each sample, we measured a range of abiotic properties and characterised the diversity of bacterial communities using 16S rRNA gene amplicon sequencing. The alpha diversity of bacterial communities in mangroves exceeded that of freshwater wetlands, which were dominated by members of the Acidobacteria, Alphaproteobacteria and Verrucomicrobia, and associated with high soil pore-water concentrations of soluble reactive phosphorous, and nitrogen as nitrate and nitrite (N-NOX−). Bacterial communities in the saltmarsh were strongly stratified by depth and included members of the Actinobacteria, Chloroflexi, and Deltaproteobacteria. Finally, the mangroves were dominated by representatives of Deltaproteobacteria, mainly Desulfobacteraceae and Synthrophobacteraceae, and were associated with high salinity and soil pore-water concentrations of ammonium (N-NH4+). These communities suggest methane consumption in freshwater wetlands, and sulfate reduction in deep soils of marshes and in mangroves. Our work contributes to the important goal of describing reference conditions for specific wetlands in terms of both bacterial communities and their drivers. This information may be used to monitor change and assess wetland health and function.

Important value aspect of mangrove community at coastal area of Pangkalpinang City, Bangka Island

Mangrove is a one of high - level plants becouse it has structure roots, branches and leafes. Mangrove commonly was found in the delta or brakishwater, but has ecological benefit as well as economic value. Mangrove found in the intertidal zone and high tide level. This research was aimed to analysis important value aspect of species mangroves at coastal area of Pangkalpinang City. This study uses a purposive sampling method. Data was collected using the line and plot transect method (LTP) and hemisphere photography agreed upon for mangrove monitoring in the COREMAP-CTI. The results showed that Mangrove composition found in 5 stations as many as 22 species mangroves which were classified into 10 family Rhizophoraceae, Sonneratiaceae, Avicenniaceae, Meliaceae, Combretaceae, Rubiaceae, Euphorbiaceae, Myrcinaceae, Arecaceae, Malvaceae, Pteridaceae. The type of vegetation that has the highest INP value at the capling level is Rhizophora apiculata BI. of 266.65%, and The type of vegetation that has the highest INP value at the sapling level is Rhizophora apiculata BI. of 202.85%. Dominance species found in 5 station is Rhizophora apiculata BI and Sonneratia alba.

Abundance Telescopium telescopium at Mangrove Ecosystem in Daruba Pantai Village, Morotai Island

Mangroves are one of the most important plants in coastal areas that act as a provider of nutrients for aquatic biota. Telescopium telescopium is one of the gastropod species which is found in many mangrove ecosystem areas. The research objective was to analyze the abundance of Telescopium telescopium and the composition of the mangrove species in the waters of Daruba Pantai Village. This research was conducted from December 2019 to January 2020. The method used is quadrant transect line and Telescopium telescopium observation is done visually or directly. Telescopium telescopium abundance data were analyzed descriptively. The results of the research on mangrove communities were varied, consisting of 4-5 types of mangroves. At station (1) there are 4 types of mangroves, stations (2) and (3) there are 5 types of mangroves. The abundance of Telescopium telescopium at three stations, the highest was at station (3) 0.262 (ind / m²), Station (1) 0.212 (ind / m²) and the lowest was at station (2) 0.142 (ind / m²). The abundance of Telescopium telescopiun is found at three stations and the highest is at station (3) 0.262 (ind / m²). The composition of mangrove species contained in Telescopium telescopium are Rhizopohora apiculata, Ceriops tagal and Rhizopora mucronata.

GIS in environmental monitoring and assessment of dredging activites in a perturbed estuarine Lagoon

The study aimed at mapping and characterizing the benthic communities of Lagos Lagoon based on how the sediment define the distribution of organisms in response to dredging activity of the area. The hydrographic survey of was carried out with the aid of an echo-sounder and side-scan sonar and plotted in ArcGIS 10.3.1. The benthic macroinvertebrate ecology in relation to human activities was defined and studied in ten selected dredged stations. Habitat suitability maps of dominant species were plotted using spatial analyst tool. The removal of organisms with the sediment resulted into increased turbidity, suspended solids and modified sediment characteristics in the study area. The known venus, pachymelania, mangrove, estuarine-amphioplus and estuarine-rock macroinvertebrate communities were intact. However, there were changes in the composition of the communities with Donax acutangulus going into extinction. Multivariate analysis showed that the observed benthic communities and sediment characteristics were sandy in nature. The observed assemblage of organism was mostly dominated by bivalve - Atactodea striata of the family Mesodesmatidae at Ogun river station which was characterised by sand. The results revealed a patchy distribution of organisms having abundant macroinvertebrates with less diversity which may be as a result of the on-going dredging activities in the area.
 Keywords: Macrobenthos, bathymetry, sediment, dredging, GIS

A multiproxy analysis of extreme wave deposits in a tropical coastal lagoon in Jamaica, West Indies

The Small Island Developing States (SIDS) of the Caribbean Region are vulnerable to natural hazards including earthquakes, tsunamis and tropical cyclones that can cause widespread devastation. Sedimentary archives of these hazards are often well-preserved in coastal lagoons; however, few studies in the Caribbean have adopted a multiproxy approach to their reconstruction. Here, we present a 1200-year multiproxy record of extreme washover events deposited within a coastal mangrove lagoon on the south coast of Jamaica. Manatee Bay lagoon is a permanent fresh-brackish-water mangrove lagoon separated from the Caribbean Sea by a low-elevation carbonate beach. Fifteen sediment cores recovered along five shore-normal transects contain ostracod-rich authigenic carbonate lake muds interspersed with beds of organic lake mud and mangrove peat. The cores contain evidence of multiple palaeo-washover deposits that are readily distinguished by their sedimentology, geochemistry and microfossil assemblages. Hypersaline conditions dominated the early part of the record (~ 800 to 900 CE), and we infer a freshening of lagoonal waters and the subsequent expansion of the mangrove community following an extreme wave event that occurred some time before ~ 1290 to 1400 CE. We constrain the primary historical-washover deposit to 1810–1924 CE (2σ; 71% probability), a period characterised by extreme tectonic and meteorological events, which include the Great Kingston Earthquake of 1907 and a local episode of enhanced hurricane activity. Whilst the balance of circumstantial evidence indicates that the deposit was probably emplaced during the tsunami generated by the 1907 earthquake, we are currently unable to differentiate between tectonically and meteorologically driven washover events based on their sedimentological characteristics.

ESTIMASI SERAPAN KARBON MANGROVE MELALUI PROSES FOTOSINTESIS DI TAMAN NASIONAL BERBAK-SEMBILANG

Mangrove is the largest ecosystem in Berbak-Sembilang National Park (BSNP) South Sumatra. Mangrove has capability to absorb carbon dioxide through photosynthesis then store it in biomass, that known as Carbon sink. The purpose of this research was to estimate the ability of carbon fixation through the photosynthesis mechanism in the mangrove area of BSNP South Sumatra. This study was conducted in July-August 2017, at 12 observation stations. Data of carbon fixation through photosynthesis was estimated by using Leaf Area Index (LAI) method. The estimation of carbon fixation by photosynthesis was done for 17 dominan mangrove species in BNSP South Sumatera. The average amount of carbon absorbed by mangrove vegetation through photosynthesis mechanism in BNSP South Sumatera was 204.91 kg/ha/day. Avicennia marina and Rhizophora apiculata were the mangrove community that showed highest capability to absorb carbon through photosynthesis around 553.43 kg C/ha/day and 401.99 kg-C/ha/day, respectively. Individually, B. cylindrica had the highest capability of carbon fixation by photosynthesis mechanism (10.95 kg-C/ha/day). Our research recommended three mangrove species (A. marina, R. apiculata and B. cylindrica) for restoration species to increase carbon sink in BNSP South Sumatera based on their photosinthesis performances.

Mangrove Community Structure in Papuan Small Islands, Case Study in Biak Regency

Mangrove plays the importance of roles for the small island sustainability, both physically and ecologically. In the high-risk Pacific Ocean’s islands, small islands in Biak face typhoons, earthquakes, high waves, and tsunami effects. The study was conducted at 100 10mx10m-quadratic-plots scattered on seven small islands in Biak-Numfor Regency. Research objectives were to investigate the mangrove community structure of each island, i.e., canopy coverage, density, and morphological size, and to analyze the correlation among those parameters. The result found that mangrove was in pristine condition, large individual size with low anthropogenic threats. They were covered by a medium and dense canopy from 61.32±3.04% in Pasi to 93.88±0.14% in Meos Mangguandi. Substrate significantly influenced the level of canopy coverage and the MDS ordination of species composition. Sonneratia alba tended to be dominant in rocky sand in Pasi, Owi, Padaidori, and Wundi, while Ceriops and Rhizophora were mostly occupied the muddy sand, or Bruguiera gymnorrhiza has the highest domination in sandy mud substrate in Auki, Pai, and Meos. The canopy coverage had a significant correlation only with total density but none with the others. The height of the tree (up to 21.2 m) was found highly related to the diameter size (max: 124 cm).

Study of Mangrove Forest Change towards the Diversity and Carbon Stock of Mangroves in Segara Anakan, Cilacap

Segara Anakan Cilacap, being the largest mangrove area in Java Island, is one example of a degraded area which is mostly caused by land conversion to farming lands, ponds, housing, and industrial properties affecting the mangrove community in various ways. The objective of this research is to know the diversity and carbon stock of mangroves in different types of environmental change in Segara Anakan, Cilacap, as well as to know the correlation between environmental factors in various types of environmental change with diversity and carbon stock of mangroves in Segara Anakan, Cilacap. This research was conducted using clustered sampling from 8 stations located at the ex rice field, ex shrimp pond, illegal cutting area, and forest. The highest diversity and carbon stock value belong to stations with forest habitats with a total of 34 tons/ha of carbon stock and the highest diversity of saplings in station F1 (1.80). Correlation values between diversity and environmental factors ranged from 0.172–0.449, whereas results between carbon stock and environmental factors range from 0.065-0.724.