Mangrove Changes Research Articles

Mangrove responses to droughts since the little ice age in the Colombian Caribbean

Mangroves are ecosystems that are seriously threatened by climate change, particularly sea level rise and an increase of droughts. They are resilient to short droughts but their response to longer ones remains arguable. In this work, we studied the responses of R. mangle dominated forests on a carbonate island (El Rosario Island) to climate anomalies and their drivers at inter-annual, decadal and inter-decadal scales during the last centuries. Palynological analysis of a sediment core retrieved from an R. mangle dominated forest was used to reconstruct vegetation changes during the last 400 years. Time series, Multi-taper spectral, Fourier and correlation analyses of PDO, AMO and ENSO series were performed to identify the matches between these series and mangrove changes during this time. The pollen record showed the influence of coastal dynamics on mangrove vegetation changes on a local scale and the influence of climate on a regional one. Changes in coastal vegetation and mangroves were influenced by beach ridge formations and lagoon closing, which were, in turn, determined by shifts in wave and wind intensity. The simultaneous diminution of both types of vegetation were related to both natural (earthquake and extreme droughts) and anthropogenic disturbances. Our results also showed the replacement of the Rhizophora dominated forest by an Avicennia dominated forest when droughts became longer. The peaks of Rhizophora pollen percentages identified along the pollen record showed a 64 year recurrence cycle that dominated during the Little Ice Age (1610–1862) and a 32 year cycle during the Current Warm Period (1866–1954). While the first cycle was positively correlated with the warm phase of PDO and AMO time series, the second cycle showed a negative significant correlation with PDO, AMO and ENSO time series. During warm periods, mangroves were stressed by droughts, but as these cycles became shorter, mangroves could recover more rapidly. From 1954 to the present, no significant correlations were observed between vegetation changes and climate drivers, which is likely related to the increased anthropogenic disturbance beyond that period of time. Our results show the high resilience of mangroves to cyclic climate changes that involve droughts, winds and sea level rises but low recovery and species turnover with extreme and longer droughts and strong anthropogenic disturbances.

Understanding Dynamics of Mangrove Forest on Protected Areas of Hainan Island, China: 30 Years of Evidence from Remote Sensing

Implementation of the UN Sustainable Development Goals requires countries to determine targets for the protection, conservation, or restoration of coastal ecosystems such as mangrove forests by 2030. Satellite remote sensing provides historical and current data on the distribution and dynamics of mangrove forests, essential baseline data that are needed to design suitable policy interventions. In this study, Landsat time series were used to map trends and dynamics of mangrove change over a time span of 30 years (1987–2017) in protected areas of Hainan Island (China). A support vector machine algorithm was combined with visual interpretation of imagery and result showed alternating periods of expansion and loss of mangrove forest at seven selected sites on Hainan Island. Over this period, there was a net decrease in mangrove area of 9.3%, with anthropic activities such as land conversion for aquaculture, wastewater disposal and discharge, and tourism development appearing to be the likely drivers of this decline in cover. Long-term studies examining trends in land use cover change coupled with assessments of drivers of loss or gain enable the development of evidence based on policy and legislation. This forms the basis of financing of natural reserves of management and institutional capacity building, and facilitates public awareness and participation, including co-management.

The effect of abrasion on geomorphology changed and coast line conservation effort in Karawang Regency

The coastline in Karawang Regency stretches 84.23 km in nine sub-districts. One potential disaster is abrasion. The losses caused by abrasion have had an impact on public facilities and residents’ housing due to changes in coastlines and mangroves in Karawang District. The study aimed to obtain the distribution of abrasion along the Karawang coast and geomorphological changes that occurred from 2013-2018. The data used are Landsat Landsat 8 OLI satellite images and field surveys. The method used to analyze the rate of abrasion was carried out by spatial-temporal analysis for five years. Abrasion that occurred from 2013 - 2018 found in Pakisjaya, Cibuaya, Pedes, Cilebar, Tempuran, Cilamaya Kulon and Cilamaya Wetan Subdistricts. The efforts that have been made by the community in Cilamaya District are to conserve by planting mangroves and artificial barriers to the waves.

Mapping the multi-decadal mangrove dynamics of the Australian coastline

Mangroves globally provide a diverse array of ecosystem services but these are impacted upon by both natural and anthropogenic drivers of change. In Australia, mangroves are protected by law and hence the natural drivers predominate. To determine annual national level changes in mangroves between 1987 and 2016, their extent (by canopy cover type) and dynamics were quantified using dense time-series (nominally every 16 days cloud permitting) of 25 m spatial resolution Landsat sensor data available within Digital Earth Australia (DEA). The potential area that mangroves occupied over this period was established as the union of mangrove maps generated for 1996, 2007–2010 and 2015/16 through the Global Mangrove Watch (GMW). Within this area, the green vegetation fractional cover (GVpc) was retrieved from each available cloud-masked Landsat scene through linear spectral unmixing. The 10th percentile (GVpc10) was then determined for each calendar year by comparing these data in a time-series. The percentage Planimetric Canopy Cover (PCC%) for each Landsat pixel was then estimated using a relationship between GVpc10 and LiDAR-derived PCC% (<1 m resolution and based on acquisitions from all states supporting mangroves, excluding Victoria). The resulting annual maps of mangrove extent and cover for Australia are the first to be generated at a continental scale and on an annual basis. These indicated that the total area of mangrove forest (canopy cover >20%; resolvable at the Landsat resolution) varied from a minima of 10,715 ± 36 km2 (95% confidence interval) in 1992 to a maxima of 11,388 km2 ± 38 km2 (95% CI) in 2010, declining to 11,142 ± 57 km2 (95% CI) in 2017. In 2010 (maximum extent), the forests were classified as closed canopy (38.8%), open canopy (49.0%) and woodland mangrove (12.2%). The majority of change occurred along the northern Australian coastline and was concentrated in the major gulfs and sounds. The 30 national maps of annual mangrove extent represent a reference dataset, which is publicly available through the Terrestrial Environment Research Network (TERN) landscapes portal. Future efforts are focusing on the routine production of annual mangrove maps beyond 2019 as part of Australia's efforts to monitor the coastal environment.

Mangrove cover and cover change analysis in the transboundary area of Kenya and Tanzania during 1986–2016

ABSTRACTMangrove forests are among the most threatened ecosystems on earth. Some of these forests traverse national boundaries complicating their management due to differences in governance structures between countries. To improve the management of transboundary species regular monitoring is essential. Remotely sensed data were used to estimate forest cover and analyze conditions of mangroves in the proposed transboundary conservation area (TBCA) between Kenya and Tanzania. Image analysis was performed using unsupervised and supervised classification methods. The transboundary mangroves cover an estimated 11,906 ha; 55% being in Kenya, 45% in Tanzania. Ceriops tagal, Avicennia marina, and Rhizophora mucronata species co-dominate the mangroves of the transboundary area. The hotspot for loss and degradation of mangrove in the TBCA is Vanga in Kenya with a loss of 27 ha/yr. Harvesting of mangrove wood products have contributed to the loss of mangroves in the transboundary area. TBCA formation could play a critical role in ensuring sustainable mangrove resources utilization.

Using multi-indices approach to quantify mangrove changes over the Western Arabian Gulf along Saudi Arabia coast

Mangroves habitat present an important resource for large coastal communities benefiting from activities such as fisheries, forest products and clean water as well as protection against coastal erosion and climate related extreme events. Yet they are increasingly threatened by natural pressure and anthropogenic activities. We observed an inaccurate distribution of mangroves over the Western Arabian Gulf (WAG) which is a vital habitat and resource for the local ecosystem, according to the United Stated Geological Survey (USGS) mangrove database through spectral analysis. Change detection analysis is conducted on mangrove forests along the Saudi Arabian coast of the WAG for the years 2000, 2010 and 2018 using Landsat 7 & 8 data. Three supervised classification methodologies are employed for mangrove mapping, including Supported Vector Machine (SVM), Decision Tree (DT), referred to as Classification and Regression Trees (CART) and Random Forest (RF). CART’s accuracy was recorded to be >95% while other classifiers were >90%. The CART supervised learning classifier, mapping mangroves’ distribution and biomass using Google Earth Engine (GEE) online platform, indicates an overall increase in the northern Tarut Bay and Tarut Island, by 0.21 km2 from 2000 to 2010 and by 1.4 km2 from 2010 to 2018. The increase might be due to mitigation strategies such as mangrove breeding and plantation. It can be challenging to detect changes in certain regions due to the inadequate resolution of Landsat where submerged mangroves can be confused with salt marshes and macro algae. We employed a new method to identify and analyze submerged mangrove forests distribution via a submerged mangrove recognition index (SMRI) and Normalized Difference Vegetation Index (NDVI) in Abu Ali Island. Our results show the robustness of SMRI as an effective indicator to detect submerged mangroves in both high and medium spatial resolution satellite images. NDVI values differentiated submerged mangroves from tidal flats between Landsat 7 & 8 as well as during conditions of low and high tides. High resolution WorldView-2 image showed agreement of mangroves distribution with the SMRI and NDVI results.

Mangrove Forest Cover Change Detection Along the Coastline of Trincomalee District, Sri Lanka Using GIS and Remote Sensing Techniques

Mangroves provide valuable services to the coastal community in Trincomalee District despite they distributed in the small area. The objectives of this research are to map out the distribution of the mangroves and to detect the change in mangroves in Trincomalee District during the last 20 years. According to this study the reduction in the extent of mangroves caused by clearance for alternative land use including aquaculture, tourism. The total extent of mangroves in Trincomalee district was estimated using Landsat satellite imageries 1997 and 2017. The medium resolution of Landsat imageries may lead to underestimating relatively small, linear mangroves in coastal line of Trincomalee district. The occurrence of clouds in the coastal area can cause data gaps during analysis. This study estimated total mangroves in Trincomalee district was 20.26km2 and 15.07 km2 in 1997 and 2017 respectively and representing a loss of 5.19 km2 in the 20 years (1997-2017). Mangroves loss in the study area varied both spatially and temporally due to differences in habitat alteration pattern. However, Landsat images adequately aided to detect changes in mangroves in Trincomalee district which shows the rate of decline in mangroves.

Spatial and temporal variability of mangrove ecosystems in the Cu Lao Cham-Hoi An Biosphere Reserve, Vietnam

Mangrove ecosystems in central Vietnam play an important role in protecting the coast line; reducing erosion and salinization; as well as regulating climate. Mangrove ecosystems in Cu Lao Cham-Hoi An Biosphere Reserve contribute significantly to the role of coastal protection, climate change resilience, and local economic development. Historical satellite remote sensing data, intensive field surveys and GIS techniques have been employed in many tropical areas worldwide to detect mangrove changes. The objective of this study is to use Landsat imagery covering the past 44 years (1973–2016) to study historical changes of the mangrove ecosystems in the Cu Lao Cham-Hoi An Biosphere Reserve and to document the current distribution of species diversity in the Reserve’s mangrove ecosystems. The field surveys and analysis of satellite remote sensing data revealed that the mangrove ecosystem in Cu Lao Cham-Hoi An Biosphere Reserve has fluctuated significantly in both temporal and spatial distribution. This study has newly documented eight mangrove species to the inventory of the Cu Lao Cham-Hoi An Biosphere Reserve mangroves species composition. This study is regarded as the first study using multi-spectral satellite remote sensing image to assess the distribution status and historical changes of mangrove ecosystems in central Vietnam. The outcomes can contribute to assessing the dynamic trends of coastal ecosystem changes during the past 44 years to provide sustainable development strategies for the area.

Mangroves in the Galapagos islands: Distribution and dynamics.

Mangrove forests provide valuable coastal protection from erosion, habitat for terrestrial and marine species, nursery grounds for commercial fisheries and are economically important for tourism. Galapagos’ mangroves usually grow directly on solid lava and fragmented rocky shores, thereby stabilizing the sediment and facilitating colonisation by other plants and many animals. However, until very recently, only inaccurate data described mangrove coverage and its distribution. We mapped mangroves using freely available Google Earth Very High Resolution images based on on-screen classification and compared this method to three semi-automatic classification algorithms. We also analysed mangrove change for the period 2004–2014. We obtained an area of 3657.1 ha of fringing mangrove that covers 35% of the coastline. Eighty percent of mangrove cover is found in Isabela island, and 90% in the western and central south-eastern bioregions. The overall accuracy of mangrove classification was 99.1% with a Kappa coefficient of 0.97 when validated with field data. On-screen digitization was significantly more accurate than other tested methods. From the semi-automated methods, Maximum Likelihood Classification with prior land-sea segmentation yielded the best results. During the 2004–2014 period, mangrove coverage increased 24% mainly by expansion of existing mangroves patches as opposed to generation of new patches. We estimate that mangrove cover and growth are inversely proportional to the geological age of the islands. However, many other factors like nutrients, currents or wave exposure protection might explain this pattern. The precise localization of mangrove cover across the Galapagos islands now enables documenting whether it is changing over time.

Transborder political ecology of mangroves in Senegal and The Gambia

Abstract Existing studies of mangroves in Senegal and The Gambia have found net increases in mangrove tree cover at the national scale, but these do not accord with local accounts and explanations of loss. This paper utilizes remote sensing analysis and political ecology frameworks to assess local accounts of mangrove wood trafficking across the border between The Gambia and southern Senegal, which were encountered in conducting qualitative field research. The remote sensing results demonstrate overall increases in mangrove cover in The Gambia and in the Sine Saloum and Low Casamance estuaries in Senegal between 1988 and 2018, but also highlight greater declines in mangrove cover in Low Casamance in the 1990s—a period of heightened regional political conflict—and in particular areas of the estuary near the Gambian and Guinea-Bissauan borders. Focusing on political ecology’s attention to multiple scales of analysis, this paper addresses divergent interpretations of mangrove changes in the region, and how local accounts of destruction may not be fully captured by the scale of observation and analysis in remote sensing. The paper argues for greater attention to spatial and temporal variation in studies of mangrove dynamics, and greater consideration for how these patterns may result from confluences of political, social, and natural factors.

Correctly assessing forest change in a priority West African mangrove ecosystem: 1986–2010 An answer to Carney et al. (2014) paper “Assessing forest change in a priority West African mangrove ecosystem: 1986–2010”

In order for decision-makers to adjust environmental policy appropriately, it is essential that they utilize reliable data. Now, on a global scale, mangroves are considered endangered, yet there is a general consensus among recent scholars that mangroves in Saloum and Casamance estuaries are currently experiencing regeneration. In contrast with the results of these papers, Carney et al. (2014) published a paper in Geoforum mapping and quantifying a massive mangrove loss. However, remote sensing and mapping shortcomings have been identified. The 2010 map used in the Carney et al. (2014) paper is accurate, however, as a result of errors in georeferencing, window extraction and classification, their 1986 map is not. Mangrove and mudflats are grouped in the same class. The addition of a stacked classification to the image processing used by Carney et al. (2014) enables the realization of a correction of the map, and thus the production of results similar to other studies. The supposed loss of mangroves appears to have been the consequence of this classification error. In fact, we observe a progression of 8804 ha instead of the regression of 37,196 ha assessed by the authors. This published discrepancy, which is in opposition to any other study of this area, must be discussed in order to clarify for scholars and policymakers the actual dynamics of mangrove change in the studied region.

Local Community’s Perception of Mangrove Change Impact on Their Socioeconomic Condition in Johor, Malaysia

Mangrove forests across the globe have experienced remarkable rapid reduction over the recent few couple of decades due to land use changes and socioeconomic factors. These phenomena also have an impact on the socioeconomic condition of the local communities. This study was carried out to determine the impacts of mangrove changes on local community’s socioeconomic condition at the surroundings of Sungai Pulai Mangrove area in southwest Johor, Malaysia. A total of 360 respondents were interviewed by using a questionnaire. The perceived impacts were both negative and positive. As negative impacts, the respondents perceived ‘species and habitat loss’ followed by ‘coastal erosion’, ‘reduction of mangrove production and income’, biodiversity threatened’, ‘increase of migrants’ and ‘increased risk of livelihood’. However, as positive impacts, they perceived ‘new infrastructure developed for useful purpose replacing mangroves’ followed by ‘improved communication system’ and ‘increased the overall quality of living standards. The study concluded that the mangrove change in the study area negatively affecting to their mangrove dependency for livelihood activities whereas positively improving their living quality.

The Global Mangrove Watch—A New 2010 Global Baseline of Mangrove Extent

This study presents a new global baseline of mangrove extent for 2010 and has been released as the first output of the Global Mangrove Watch (GMW) initiative. This is the first study to apply a globally consistent and automated method for mapping mangroves, identifying a global extent of 137,600 km 2 . The overall accuracy for mangrove extent was 94.0% with a 99% likelihood that the true value is between 93.6–94.5%, using 53,878 accuracy points across 20 sites distributed globally. Using the geographic regions of the Ramsar Convention on Wetlands, Asia has the highest proportion of mangroves with 38.7% of the global total, while Latin America and the Caribbean have 20.3%, Africa has 20.0%, Oceania has 11.9%, North America has 8.4% and the European Overseas Territories have 0.7%. The methodology developed is primarily based on the classification of ALOS PALSAR and Landsat sensor data, where a habitat mask was first generated, within which the classification of mangrove was undertaken using the Extremely Randomized Trees classifier. This new globally consistent baseline will also form the basis of a mangrove monitoring system using JAXA JERS-1 SAR, ALOS PALSAR and ALOS-2 PALSAR-2 radar data to assess mangrove change from 1996 to the present. However, when using the product, users should note that a minimum mapping unit of 1 ha is recommended and that the error increases in regions of disturbance and where narrow strips or smaller fragmented areas of mangroves are present. Artefacts due to cloud cover and the Landsat-7 SLC-off error are also present in some areas, particularly regions of West Africa due to the lack of Landsat-5 data and persistence cloud cover. In the future, consideration will be given to the production of a new global baseline based on 10 m Sentinel-2 composites.

The extent of mangrove change and potential for recovery following severe Tropical Cyclone Yasi, Hinchinbrook Island, Queensland, Australia.

Cyclones are significant drivers of change within mangrove ecosystems with the extent of initial damage determined by storm severity, location and distribution (exposure), and influenced by species composition and structure (e.g., height). The long‐term recovery of mangroves is often dependent upon hydrological regimes, as well as the frequency of storm events. On February 3, 2011, Tropical Cyclone Yasi (Category 5) made landfall on the coast of north Queensland Australia with its path crossing the extensive mangroves within and surrounding Hinchinbrook Island National Park. Based on a combination of Landsat‐derived foliage projective cover (FPC), Queensland Globe aerial imagery, and RapidEye imagery, 16% of the 13,795 ha of mangroves experienced severe windthrow during the storm. The greatest damage from the cyclone was inflicted on mangrove forests dominated primarily by Rhizophora stylosa, whose large prop roots were unable to support them as wind speeds exceeded 280 km/hr. Classification of 2016 RapidEye data indicated that many areas of damage had experienced no or very limited recovery in the period following the cyclone, with this confirmed by a rapid decline in Landsat‐derived FPC (from levels > 90% from 1986 to just prior to the cyclone to < 20% postcyclone) and no noticeable increase in subsequent years. Advanced Land Observing Satellite (ALOS‐1) Phased Arrayed L‐band Synthetic Aperture Radar (SAR) L‐band HH backscatter also increased initially and rapidly to 5 ± 2 dB (2007–2011) due to the increase in woody debris but then decreased subsequently to −20 ± 2 dB (postcyclone), as this decomposed or was removed. The lack of recovery in affected areas was attributed to the inability of mangrove species, particularly R. stylosa, to resprout from remaining plant material and persistent inundation due to a decrease in sediment elevation thereby preventing propagule establishment. This study indicates that increases in storm intensity predicted with changes in global climate may lead to a reduction in the area, diversity, and abundance of mangroves surrounding Hinchinbrook Island.

Characterizing landscape patterns in changing mangrove ecosystems at high latitudes using spatial metrics

Mangroves are coastal ecosystems and a detailed characterization of their spatial metrics is important to understand the underlying processes of mangrove change and to inform future mangrove management. The main objectives of this study were: (1) to determine the past (1940) and current (2014) spatial metrics of mangroves at high latitudes and (2) to assess the relationship between spatial metrics and land-based, climatic and oceanic factors in 2014. Mangroves were mapped into categories of tall and dwarf mangroves, as well as into delta, riverine and estuarine mangroves based on field surveys, satellite images and aerial photographs across 38 estuaries of varying size in the Auckland Region, New Zealand. Fragstats was applied to determine spatial metrics indices related to complexity, connectivity, and configuration of mangrove patches. While the number of mangrove patches remained stable, mangrove patch size increased significantly (75%) suggesting that the increase in total mangrove area in the Auckland Region is mainly driven by an increase in patch size. Tall mangroves became more fragmented, through both reduction in connectivity (Mean Proximity Index in 2014 = 214, decrease of 35%) and their shape becoming more irregular (Mean Shape Index in 2014 = 1.9, an increase of 24%). Catchment related factors (e.g., sediment accumulation rate) had a strong effect on the total mangrove area and number of patches. In contrast, mean patch size and patch connectivity were influenced by nitrogen concentration, mean wave height and tidal amplitude, which in combination explained up to 63% of the variability. These findings can be used to facilitate decision-making concerning the sustainable future management of mangroves.

Mapping Mangrove Extent and Change: A Globally Applicable Approach

This study demonstrates a globally applicable method for monitoring mangrove forest extent at high spatial resolution. A 2010 mangrove baseline was classified for 16 study areas using a combination of ALOS PALSAR and Landsat composite imagery within a random forests classifier. A novel map-to-image change method was used to detect annual and decadal changes in extent using ALOS PALSAR/JERS-1 imagery. The map-to-image method presented makes fewer assumptions of the data than existing methods, is less sensitive to variation between scenes due to environmental factors (e.g., tide or soil moisture) and is able to automatically identify a change threshold. Change maps were derived from the 2010 baseline to 1996 using JERS-1 SAR and to 2007, 2008 and 2009 using ALOS PALSAR. This study demonstrated results for 16 known hotspots of mangrove change distributed globally, with a total mangrove area of 2,529,760 ha. The method was demonstrated to have accuracies consistently in excess of 90% (overall accuracy: 92.2–93.3%, kappa: 0.86) for mapping baseline extent. The accuracies of the change maps were more variable and were dependent upon the time period between images and number of change features. Total change from 1996 to 2010 was 204,850 ha (127,990 ha gain, 76,860 ha loss), with the highest gains observed in French Guiana (15,570 ha) and the highest losses observed in East Kalimantan, Indonesia (23,003 ha). Changes in mangrove extent were the consequence of both natural and anthropogenic drivers, yielding net increases or decreases in extent dependent upon the study site. These updated maps are of importance to the mangrove research community, particularly as the continual updating of the baseline with currently available and anticipated spaceborne sensors. It is recommended that mangrove baselines are updated on at least a 5-year interval to suit the requirements of policy makers.

Monitoring Mangrove forest landcover changes in the coastline of Bangladesh from 1976 to 2015

This study used multi-date Landsat images to quantify mangrove cover changes in the whole of Bangladesh from 1976 to 2015. Images were pre-processed with an atmospheric correction using Dark Object Subtraction (DOS) and Relative Radiometric Normalization (RRN) using Pseudo-Invariant Features (PIFs). Land Use/Land Cover (LU/LC) classification map was generated using Maximum Likelihood (MaxLike) algorithm, indicating the areal extent of mangroves increased by 3.1% between 1976 and 2015, where 1.79% of this increase occurred between 2000 and 2015. Though mangrove areas remained almost constant in the Sundarbans, Chakaria Sundarbans has almost disappeared between 1976 and 1989. The overall accuracy of Landsat MSS, TM, ETM+, and L8 OLI classified images were 80%, 80%, 87%, and 97% respectively. The study also found deforestation, shrimp & salt farm, coastal erosion and sedimentation, and mangrove plantation could be responsible for mangrove changes in Bangladesh.

Mapping forty years of mangrove cover trends and their implications for flats fisheries in Ciénaga de Zapata, Cuba

The mangrove forests of Cienaga de Zapata, Cuba, support populations of bonefish (Albula vulpes), tarpon (Megalops atlanticus), permit (Trachinotus falcatus), and common snook (Centropomus undecimalis) that play key roles in the local sport fishing industry. Despite their importance, no published work has documented changes in these mangroves’ extent throughout the past four decades. This project used unsupervised classification of Landsat imagery to quantify areal changes in Zapata’s mangrove forests from 1974 to 2017. Results demonstrated a 6.48% decrease in mangrove area over the course of the entire study period. However, rates of mangrove change were not uniformly distributed. The most substantial decrease in mangrove extent occurred when Hurricane Michelle struck Zapata in November 2001, reducing mangrove area by 5.56%. Between 2002 and 2014, Zapata’s mangrove extent increased by 5.03%, demonstrating the resilience of the peninsula’s mangrove forest to hurricane disturbance. Results suggest that Zapata’s national park designation has largely protected its mangroves from anthropogenic destruction, and that hurricane disturbance has been a more substantial driver of change in this important coastal ecosystem. The resilience of Zapata’s mangroves to natural hurricane disturbance and their minimal exposure to anthropogenic disturbance offer encouraging evidence for the continued conservation of Zapata’s flats fisheries.

Community Perception on Mangrove Change Issue in Southwest Johor, Malaysia

Mangroves are important coastal resources that provide both tangible and intangible benefits to the locals as well as others. Rapid coastal development pressures the mangroves to decline continuously. The objective of the study was to comprehend the perception of the locals on mangrove change issue and also to analyze the differences of perceptions among selected socioeconomic factors. Research conducted with a questionnaire survey with 5 point likert type answering options among 196 local respondents from three mukims namely Jelutong, Tanjung Kupang and Serkat. Mean perception score was 3.67 which indicated respondents agreement with the mangrove change issue. The Anova shows the perception score significantly differed among different age groups however there was no difference of perceptions among the rest variables such as race, marital status or education level. The findings of the study concluded that regardless of socioeconomic factors (except age) the respondents were concurred with the situation of mangrove loss in the studied mukims.

Zonation and Directional Dynamics of Mangrove Forests Derived from Time-Series Satellite Imagery in Mai Po, Hong Kong

Mangrove deforestation is occurring globally at a rapid rate, and is causing serious ecological and economic losses on all scales. Monitoring mangrove changes is the first important step for mangrove management and conservation. Zonation of mangrove species (ZMS) is the predictable and discrete ordering of mangrove species caused by a unique, intertidal environment. Mapping the ZMS is critical to understanding the mangrove community at a species level. In this paper, the Standard Deviational Ellipse (SDE) was proposed as a method to evaluate mangrove species from a new dimension of directional changes. Three dominant mangrove species, Kandelia obovata (KO), Avicennia marina (AM), and Acanthus ilicifolius (AI), in Mai Po, Hong Kong were analyzed using SDEs based on the time series Système Pour l’Observation de la Terre (SPOT) and Gaofen-1 (GF-1) satellite images. The SDE results demonstrated that in the past 25 years: (1) The overall spatial extent of the mangroves in Mai Po expanded significantly, approximately from 150 to 350 Ha, and show a zonation pattern with a clear sequence of species perpendicular to the shoreline; (2) KO was the dominant species in most years, showing the strongest directional characteristic; (3) All three species zones have moved toward the north and west, as observed by the SDE centers. The SDE was proved to be a useful tool for understanding the temporal and spatial changes of mangrove zonation.