Mangrove Habitats Research Articles

Assessment of suitable habitat of mangrove species for prioritizing restoration in coastal ecosystem of Sundarban Biosphere Reserve, India

Mangrove forests being the abode of diverse fauna and flora are vital for healthy coastal ecosystems. These forests act as a carbon sequester and protection shield against floods, storms, and cyclones. The mangroves of the Sundarban Biosphere Reserve (SBR), being one of the most dynamic and productive ecosystems in the world are in constant degradation. Hence, habitat suitability assessment of mangrove species is of paramount significance for its restoration and ecological benefits. The study aims to assess and prioritize restoration targets for 18 true mangrove species using 10 machine-learning algorithm-based habitat suitability models in the SBR. We identified the degraded mangrove areas between 1975 and 2020 by using Landsat images and field verification. The reserve was divided into 5609 grids using 1 km gird size for understanding the nature of mangrove degradation and collection of species occurrence data. A total of 36 parameters covering physical, environmental, soil, water, bio-climatic and disturbance aspects were chosen for habitat suitability assessment. Niche overlay function and grid-based habitat suitability classes were used to identify the species-based restoration prioritize grids. Habitat suitability analysis revealed that nearly half of the grids are highly suitable for mangrove habitat in the Reserve. Restoration within highly suitable mangrove grids could be achieved in the areas covered with less than 75 percent mangroves and lesser anthropogenic disturbance. The study calls for devising effective management strategies for monitoring and conserving the degraded mangrove cover. Monitoring and effective management strategies can help in maintaining and conserving the degraded mangrove cover. The model proves to be useful for assessing site suitability for restoring mangroves. The other geographical regions interested in assessing habitat suitability and prioritizing the restoration of mangroves may find the methodology adopted in this study effective.

Bird Diversity as a Support of Ecotourism Activities in the Mangrove Ecosystem of Lembongan Island Bali

Research has been carried out on bird diversity to support ecotourism attractions in the mangrove area of Lembongan Island. The research was conducted in April - August 2021. The focus of this research is the identification, description of bird species and the use of habitats for bird activities. To achieve this goal, the following steps were taken: Identification of bird species based on morphological characteristics, determining the abundance of bird species using the point count method, determining bird activity at each ecosystem site of mangroves with ad libitum sampling method. Bird species diversity was determined by the Shannon-Wiener index. The results of the study found 32 species of birds belonging to 26 families. Most of the birds found were terrestrial birds with 21 species, and water birds (shore birds) with 11 species. Overall, the diversity of bird species in the mangrove ecosystem is in the high category (diversity index 3.03) and the species evenness index is high (evenness index 0.87). The types of vegetation used by birds at the 7 research sites were mangrove vegetation, mangrove associations and dry land vegetation. The presence of birds, bird conservation status, bird activities, habitat use by birds in mangrove habitats are attractive attractions for ecotourism.

Coastal Biodiversity, Sustainable Livelihood and Ecological Scenarios in Marine Wetland of Asarama Andoni in Parts of Eastern Niger Delta Nigeria

Wetland ecosystems are very important natural environmental resource that forms part of the total wealth of a nation. The Asarama wetland in Andoni is amongst the important wetlands in coastal marine cosystems of the Niger Delta; fascinated by diverse rich biodiversity, wetland ecotypes of mangrove, mudflat, Nypa, estuary and fresh water forest habitats with range of critical ecosystem services they provide for mankind survival. The data gathering involved both primary and secondary sources of information. Result revealed diverse ecological scenarios: a livelihood system with diverse level of significant sources and benefit of the ecosystem services. Food, aquacultural practices and sea route logistic component of livelihood benefit from sources recorded significant (HS- 4) level of provisioning services, breeding / nursery benefit with high significant (HS- 4) level of supporting services among other levels recorded in Table 1. Ecological challenges revealed nypa palm invasion of the mangrove ecotypes and uncertainty of climatic relationship to hydrological tidal regime as natural scenarios; economic, social, institutional and infrastructural challenges as anthropogenic scenarios. Therefore a policy framework (legislature) as part of future directive and initiatives to enforce the practice of biodiversity priorities and sustainable livelihood is of immediate importance to Asarama - Andoni wetlands ecosystem. Keywords: Likert scale, provisioning, cultural, regulatory, supporting, natural, anthropogenic. DOI: 10.7176/JESD/13-24-03 Publication date: December 31 st 2022

The effect of distance planting of red mangrove (Rhizophoraapiculata) on Pulau Sembilan, PangkalanSusu District, Langkat Regency

Mangroves are a very important coastal resource for socio-economic development In addition, mangrove habitats contribute to complex food webs and energy transfer. This research was conducted in the mangrove forest area of Pulau Sembilan Village, Pangkalan Susu. This research activity was carried out for 3 months from October to December 2022. Observations in this study were carried out every two weeks. This study was based on a completely randomized design (CRD) with 5 treatments with 6 replications. The treatment in question is the spacing with P0 = 46 meters, P1 = 47 meters, P2 = 48 meters, P3 = 49 meters and P4 = 50 meters. From the research on the effect of plant spacing on Rhizophoraapiculata, the highest seedling height growth was obtained in the P0 treatment (40m spacing) with a value of 213.2 cm or average 35.5 cm. The highest increase in plant diameter was found in the P0 treatment with a value of 7.59mm or average 1.27 mm. The highest added value was found in treatment P2 with a value of 37.0 cm. The increase in leaf length is 55.4 cm which is found in the P4 treatment.

Biosynthesis and biodegradation of poly(3-hydroxybutyrate) from Priestia flexa; A promising mangrove halophyte towards the development of sustainable eco-friendly bioplastics

The protracted persistence of petrochemical plastics in the environment and their non-biodegradability impede the survival of living creatures. Recently, biopolymers are being thoroughly researched as a potential replacement for conventional plastics. This present study sought to locate Poly(3-hydroxybutyrate) synthesizing bacterial species prevalent in the mangrove ecosystem. Six halophilic bacterial isolates were obtained from the mangrove habitat, four isolates displayed superior cell dry weight as well as PHB accumulation. Isolate PMPHB5 showed the highest cell dry weight (4.92 ± 0.02 g/L), while the maximum PHA yield (80%) was found with PMPHB7. Hence, PMPHB7 was chosen for further optimization of carbon source wherein glucose demonstrated improved cell growth as well as PHB production. The characterization of the PHB granules was performed by FT-IR spectroscopy and FE-SEM EDX. The presence of characteristic elements in the sample was confirmed using EDX. Isolate PMPHB7 was further identified as Priestia flexa through 16S rRNA gene sequencing (GenBank accession number: ON362236) and a phylogenetic tree was constructed to reveal the molecular relationships of this organism with others. The solvent-cast biopolymer film was made to check the biodegradability of the extracted PHB. When buried in soil, it was found that the biopolymer film exhibited approximately 73% biodegradation after 21 days. Thus, the present study sheds light on the potential of mangrove-associated halophytes to efficiently produce PHB that is readily biodegradable in soil.

Molecular Identification of Biofilm-Forming Marine Bacterial Strains Isolated from Different Substrates of Mangrove Habitat

Molecular Identification of Biofilm-Forming Marine Bacterial Strains Isolated from Different Substrates of Mangrove Habitat

Ecological risk assessment and phytomanagement of trace metals in the sediments of mangroves associated with the Ramsar sites of Kerala, southern India.

The study investigated trace metal accumulation in the sediments of three major mangrove ecosystems associated with the Ramsar sites of Kerala state, the ecological risks they pose, and the absorption, accumulation, and translocation of metals in five dominant mangrove species, as these systems are heavily impacted by anthropogenic interventions. The trace metal concentrations (mg kg-1) in the sediment of different mangrove habitats of Kerala ranged from 20 to 295 for Cu, 65 to 350 for Zn, 72 to 151 for Pb, 11 to 210 for Ni, 42 to 228 for Mn, 0 to 6 for Cd,124 to 565 for Cr, and 0 to 2.9 for Ag. An overall enrichment of metals was recorded in sediment, exceeding the prescribed effects range median (ERM) of consensus-based sediment quality guidelines (SQGs) for Cu and Cr concentrations at Munroe Island and Ni at Vypin, indicating a detrimental risk to biota in the sediments. Principal component analysis and a higher geoaccumulation index indicated the contribution of trace metals from industries, agricultural runoff, and urban waste disposal. The ecological risk index suggested that cadmium poses a very high risk to the mangrove ecosystem at Vypin. Furthermore, the bioconcentration factor for various trace metals in Avicennia marina and Lumnitzera racemosa in Ayiramthengu was > 2, suggesting that these species can accumulate trace metals, particularly Cr, Cd, and Pb. Further, our findings suggest that A. marina may be considered as an efficient metal trap for Cd in aerial parts, as indicated by the significant translocation factor (> 1) combined with the bioconcentration factor. Therefore, the study revealed that Munroe island and Vypin had a considerable level of contamination for toxic metals and Avicennia marina could be a promising candidate species for the phytoremediation of these trace metals in the coastal settings of Kerala state.

The role of bio-geomorphic feedbacks in shaping microplastic burial in blue carbon habitats

Coastal sediments are considered as hotspots of microplastics (MPs), with substantial MPs stocks found in blue carbon habitats such as mangroves and tidal marshes, where wave-damping vegetation reduces sediment erosion and enhances accretion. Here, we examined the effects of such bio-geomorphic feedbacks in shaping MPs burial, through a year-round field study in a mangrove habitat along the coast of South China. The results revealed that MPs abundance decreased significantly with the increase of cumulative sediment erosion as the strength of bio-geomorphic feedbacks declined. More shapes and colors of MPs were found at locations with weaker waves and less sediment erosion, where the average particle size was also higher. Our findings highlight the importance of bio-geomorphic feedbacks in affecting both the abundance and characteristics of the buried MPs. Such knowledge extends our understanding of MPs transport and burial from the perspective of bio-geomorphology, which is essential to assess and predict MPs accumulation patterns as well as its impacts on ecosystem functioning of the blue carbon habitats.

Biological aspects of Diopatra sp. (Onuphidae, Polychaeta) collected from mangrove habitats of Jeruklegi, Cilacap Regency

Diopatra species are members of the family Onuphidae (Polychaeta, Annelida) that are widely used as fishing bait. These tubicolous worms are common in particular mangrove areas of Cilacap. However, biological aspects of Diopatra sp. inhabiting the areas have not been studied. In the present work, we investigated several biological aspects of the worms, including the segment number, the body weight and the sex ratio, based on Diopatra samples collected from four mangrove habitats of Jeruklegi Village, Cilacap Regency, between June and July 2021. The results show that the average numbers of segments of Diopatra sp. obtained ranged from 195 to 216 segments, whereas the average body weights ranged from 2.03 to 3.12 g, and the average sex ratios ranged from 0.5 to 1.3. In general, the biological aspects of Diopatra sp. between sampling sites were relatively similar; this can be attributed to the similar environmental conditions at all sampling sites, including salinity (25–32 ppt), water temperature (30–32 oC), dissolved oxygen (6.4–8.8 ppm) and pH (7). While Diopatra worm farming is necessary so that local people do not rely on natural catch, a further taxonomic study is required to reveal the identity of this economically important local species.Keywords:Biological aspectDiopatraMangrove habitatPolychaetesTubicolous worms

Community structure of the Fiddler Crab (<i>Uca</i> spp.) at Bahak Indah Beach, Tongas, Probolinggo – East Java

The fiddler crab (Uca spp.) is a type of animal belonging to the crustacean group that lives on the coast of Bahak Indah, Tongas, Probolinggo. The high level of anthropogenic activity on the beach of Bahak Indah makes the fiddler crab community increasingly depressed and its habitat decreasing. The purpose of this study was to compare the community structure of fiddler crabs at Bahak Beach, Tongas, Probolinggo. The study was conducted in January – February 2022. The determination of observation stations was purposive based on the consideration of the presence and absence of mangrove vegetation. Sampling of fiddler crabs used a systematic sampling method using transects and plots. Community structure data analysis includes diversity, uniformity, and dominance indices displayed in graphical form. Based on the results of the study found 4 types of fiddler crabs in Bahak Indah Beach, namely Uca cryptica, Uca perplexa, Uca coarctata, and Uca dussumieri. The value of diversity on the beach with mangrove habitat is in the medium category, while on the beach habitat without mangrove vegetation it is in the low category. The uniformity value obtained in mangrove habitats is in the high category, while in coastal habitats without mangrove vegetation it is found in the medium category. On the other hand, the dominance index value is in the low category in coastal habitats with mangrove vegetation, and the moderate category in coastal habitats without mangrove vegetation. The relationship between the Diversity (H') of the fiddler crab and the environmental conditions of the Bahak Indah Beach waters is that it has a positive correlation with water pH parameters with sufficient correlation and soil pH with a strong correlation. While the correlation with temperature parameters is strong but negative. Likewise, salinity is quite strong but negative.

Ecological assessment of physico-chemical properties in mangrove environments along the Arabian Gulf and the Red Sea coasts of Saudi Arabia

Urban expansion along the coastal sites is one of the major causes of the deterioration of mangrove habitats. This study aimed to report the current status of different mangrove environments in Saudi Arabia. Mangrove soil and sediment–water samples were collected from the coasts of the Arabian Gulf and the Red Sea for their physical, chemical, and heavy metal analysis. The mean values (n = 42) of heavy metals in the soil showed that Fe (2200 ppm) > Mn (91.9 ppm) > Zn (66.11 ppm) > Cr (62.40 ppm) > Ni (33.64 ppm) > Cu (31.06 ppm) > Pb (30.69 ppm) > Co (27.06 ppm). While the mean values (n = 15) of heavy metals in the sediment–water were as follows; Cr (0.1978 ppm) > Fe (0.1016 ppm) > Pb (0.0792 ppm) > Co (0.0706 ppm) > Mn (0.0356 ppm) > Cu (0.0317 ppm) > Ni (0.0215 ppm). The average values of Zn, Ni, Cu, Pb, and Co were greater than those reported previously in the Red Sea and Arabian Gulf coastal sediments. At the same time, Mo and Cd were not detected in any studied soil sample. The correlation analysis revealed that the EC of mangrove soil was positively correlated with SOM, Ca, Mg, Na, and K, while the EC of sediment–water was positively correlated with Na, K, and Cu. Landfilling, sewage pollution, mismanagement of solid waste, and contamination due to other anthropogenic activities may lead to heavy metal hazards and the loss of large areas of mangrove plants in this region. Therefore, the findings of this study should be considered to understand and design the management strategy of mangrove forests in the area of study.

Redescription of Pseudograpsus intermedius Chhapgar, 1955 (Decapoda, Brachyura, Varunidae) from India

The identity of Pseudograpsus intermedius Chhapgar, 1955 (Varunidae), a crab species found in mangrove habitats of India is clarified. The re-examination of the holotype male and examination of fresh specimens collected from Goa State, India, revealed that P. intermedius shows significant morphological differences from the generic characters of Pseudograpsus. As such, a new genus Chhapgarus n. gen. is established for the species.

Dispersal and coastal geomorphology limit potential for mangrove range expansion under climate change

Abstract Latitudinal range limits for mangroves on high‐energy, wave‐dominated coasts are controlled by geomorphological features and estuarine dynamics. Mangroves reach a southern global range limit along the South African coastline, but the distribution is patchy, with stands occurring in only 16% of the estuaries in the region. Yet, the persistence of forests planted >50 years ago beyond the natural distribution limit suggests that additional estuaries could support mangroves. Understanding regional drivers is necessary to inform global‐scale estimates for how this important ecosystem is predicted to respond to climate change. Here, we combine species distribution modelling (MaxEnt), Lagrangian particle tracking using an eddy‐ and tide‐resolving numerical ocean model, and connectivity matrices, to identify suitable mangrove habitats along the South African coastline at present, as well as under the IPCC RCP4.5 and RCP8.5 climate scenarios. Within the current South African distribution range (±900 km), eight more estuaries were identified to be suitable under contemporary conditions. When considering potential range extension (±110 km), an additional 14 suitable estuaries were identified. Connectivity matrices suggest limited long‐distance dispersal, stranding mostly at or near the release location, and a decreased probability of connectivity towards the range limit. Under both future climate scenarios, 30% of estuaries currently supporting mangroves are predicted to become unsuitable, while an additional six estuaries beyond the current distribution are predicted to become suitable. However, there is limited connectivity between these new sites and established forests. Synthesis. This study shows that dispersal substantially limits mangrove distribution at the southern African range limit and highlights the importance of including this process in species distribution models. Ultimately, our results provide new insight into mangrove conservation and management at range limits that are not controlled predominantly by temperature, as it has been assumed that mangroves will largely expand to higher latitudes under climate change.

Total ecosystem blue carbon stocks and sequestration potential along a naturally regenerated mangrove forest chronosequence

Naturally regenerated (NR) mangroves offer an excellent passive approach for climate change mitigation and adaptation under UN decade of restoration program. However, the support of NR mangroves on total ecosystem carbon (TEC) stocks and sequestration potential remained unclear across forest stand development process that can significantly vary spatially and temporally due to regeneration age. Using the ‘space for time’ approach, this study quantified the TEC stocks along the Merlimau - Kuala Sebatu fringing mangrove habitat expansion chrono-sequence that comprised of 3, 6, 12, 18, 25 years age and intact stands. We also estimated the carbon (C) sequestration potential of each stand-age by comparing with un-vegetated mudflats as control. We collected aboveground tree, belowground root, downed woody debris, litterfall and soil core up to 2 m for TEC quantification and C sequestration. Mean TEC stocks ranged from 232 ± 69 to 296 ± 49 Mg C/ha for NR3 and NR25 respectively at the study area. TEC stocks from different aged NR and intact mangroves were not significantly different from each other and therefore did not affect by age. Aboveground trees C and downed wood C pools were significantly affected by stand-age. In contrast, sediment C stocks (representing up to 80 %) remained generic over many years, driving the constant of TEC stocks in this study. Equally affected by age, the NR mangroves sequestered total C of 2.28 to 17.38 (mean ± SE: 7.36 ± 1.88 Mg C/ha yr−1), with younger stands (NR3) holding almost six times higher total C sequestration rates than older mangroves (NR25). Our study suggests that highly suspended sediments driving from upstream, especially in the younger mangrove stands at a lower elevation, supports higher bulk density and C accumulation rate in the sediment as they expand seaward. This study proves that NR mangroves comprised primarily of younger mangrove stands can be a C sequestrator powerhouse that promises nature-based climate solutions through avoidance and management. Though, future research is needed to understand how better management and conservation practices can affect or towards increasing trend of TEC especially sediment carbon stock that holds almost 80 % of total TEC.

Diversity of reef fish species in presence of mangrove habitat in Ternate, North Maluku, Indonesia

Abstract. Utama RS, Renyaan J, Nurdiansah D, Makatipu PC, Suyadi, Hapsari BW, Martha E, Rahayu EMD, Sugiharto A. Akbar N. 2022. Diversity of reef fish species in presence of mangrove habitat in Ternate, North Maluku, Indonesia. Biodiversitas 23: 5184-5193. Research on reef fish has been widely reported, where information about reef fish communities is an important factor for evaluating fisheries management and coral reef management. Mangroves as the nursery, foraging, and growing areas were also important to assure sustainable reef fish fisheries. This paper studies reef fish abundance and diversity in Ternate Waters in the presence of mangrove in coral reef habitats. To determines coral reef condition underwater photo transect was performed while an underwater visual census (UVC) was used to determine the abundance and diversity of reef fishes in Ternate waters between 2017 and 2018. A total of 14 stations were used, with eight stations near the mangroves and six stations that did not contain mangroves. Based on the observation, fish species richness in mangrove absence was higher than in the presence of mangroves, with 68 and 65 species in 2017 and 66 and 62 species in 2018. However, the abundance of reef fish was recorded high in the presence of mangroves than in the absence of mangroves, with 390 and 289 individual differences in 2017 and 2018. Mangroves' complexity affected part of reef fish communities in Ternate water, particularly Lutjanidae, Serranidae, and Scaridae, which might influence the abundance of reef fishes rather than the species richness. In addition, carnivore shows a negative effect in the presence of mangroves, in contrast with herbivores. It is related to mangrove functioning as a temporary shelter when high-pressure presence in their natural habitat (reef) and a place for foraging. Therefore, mangrove management must be a consideration in the coral reef or fisheries management program.

Trophodynamics of Nekton Assemblages and Relationships with Estuarine Habitat Structure Across a Subtropical Estuary

Understanding the spatiotemporal dynamics of trophic structures, or trophodynamics, is important for assessing the overall condition and function of estuarine ecosystems. We examined spatial and seasonal trophodynamics of nekton assemblages across the seascape of a subtropical estuary (Charlotte Harbor, FL, USA) using historical nekton data from an ongoing monitoring program. We also examined relationships between trophodynamics and the spatial distribution of vegetated habitats, such as salt marshes, mangroves, and seagrass beds, as well as their absence along hardened shorelines (seawalls or riprap) using seascape metrics (area and edge density of habitats within several search radii of sample locations). We found that nekton assemblages in shallow waters (from the shoreline to a depth of ≤ 1.5 m) transitioned from mainly planktivores in the lower Peace and Myakka Rivers to mainly benthivores (those feeding on benthic infauna, epifauna, or seagrass) in the middle and lower portions of Charlotte Harbor. Overall nekton assemblages throughout the estuary appeared to be largely sustained through benthic pathways in areas with abundant seagrass and nearby mangrove habitat, particularly during the cool-dry winter when planktivore densities were seasonally low. The dramatic seasonal decline in planktivore densities we found in the lower rivers may be related to low freshwater inflow and increased predation resulting from seasonal recruitment pulses of several omnivorous species. Trophodynamics linked with seascape metrics of estuarine habitat structure described here may be used as a spatially explicit baseline of the estuarine seascape to monitor ecosystem health as well as parameterize spatial ecosystem models used in fisheries management in Charlotte Harbor and similar subtropical estuaries.

Mapping mangrove sustainability in the face of sea level rise and land use: A case study on Leizhou Peninsula, China

Habitat loss and degradation of mangrove forests can be caused by both sea level rise (SLR) and unsustainable land practices. Current long-term change projections are often based on changes to mangrove extent; however, this may overlook fragmentation and the associated habitat resilience decline and therefore fail to adequately reveal the risks to mangrove habitats. A mangrove sustainability index (MSI) was proposed in this study to assess the impact of SLR and land use on mangrove habitats. The index consists of four components: habitat area change, habitat quality, landscape pattern, and protection ratio. Ecological models and landscape models were combined to calculate the MSI. Considering the SLR under RCP4.5 and RCP8.5 and land use strategies, four scenarios were set with prediction periods of base year (2020) to 2050 and 2100. The Leizhou Peninsula, China was used as the case study. The results showed that dual stressors would reduce the extent of mangroves by 16.6%–56.2%. Habitat quality was sensitive to land use change but was not affected by SLR. Landscape pattern and protection ratio were influenced by SLR but less effected by land use. In all scenarios, mangroves tended to migrate out of the protected areas, with protection ratio decreasing from 37% to 16.9%–29.9%. Newly expanding habitats may suffer from patch fragmentation and low connectivity. Unsustainable mangrove distribution sites on Leizhou Peninsula were identified as hotspots for management. Projections under different scenarios showed that some unsustainable sites could be reversed to sustainable sites through improvements in land use policies. The proposed approach could provide essential tools for the formulation of mangrove conservation and restoration strategies adapted to climate change.

Past and potential future distribution of white mangroves in an arid estuarine environment: Integration of Maxent and CA-Markov models

This study performed a coupled modeling approach to assess the past-to-future distribution of white mangrove trees (Avicennia marina) along an intertidal zone in the Strait of Hormuz. Historical mangrove distributions were extracted from 3 temporally-median-filtered Landsat images in 2002 (ETM+), 2011 (TM), and 2020 (OLI). The mangrove habitat suitability was investigated using the Maxent model, employing distance from shoreline, creeks, and mangroves, elevation and sediment physio-chemical characteristics. The sediment attributes including EC, pH, sediment texture, total organic carbon, bulk density, and total nitrogen and phosphorous were measured at 25 sampling points and interpolated using the IDW technique. The resulting habitat layer was used as the transition layer in the CA-Markov to predict the future distribution of mangroves by 2030 and 2040. From 2002–2020, the mangrove cover increased by 165 ha (annual rate of 8.19 ha) through both edge- and out-growth patterns. The habitat suitability modeling was performed successfully with an AUC of 0.962 with distance from mangrove patches, distance from water creeks, sediment texture, and phosphorous as the most important predictors. According to the CA-Markov prediction (AUC of 0.690), the area of mangroves is projected to increase to 497 and 543 ha in a compact edge-growth pattern by 2030 and 2040, respectively.

Interpreting Mangrove Habitat and Coastal Land Cover Change in the Greater Bay Area, Southern China, from 1924 to 2020 Using Historical Aerial Photos and Multiple Sources of Satellite Data

Coastal habitat dynamics and ecosystem function in response to human-induced disturbance, especially urbanization, are of increasing concern. However, how changes in landscape composition as well as habitat quantity and quality may affect the long-term sustainability of rapidly urbanizing coasts remains unclear. This study aimed to quantify the extent, change rate, patterns, change process and interrelationships of mangrove habitats, impervious surfaces, and other land cover types in Deep Bay in the Guangdong-Hong Kong-Macau Greater Bay Area (GBA), China, the world’s largest megalopolis, from 1924 to 2020. We processed historical aerial photos (1924–2020) and multiple sources of satellite data (1973–2020) for different types of land cover mapping. Post-classification analysis, including correlation analysis and change detection analysis, was conducted based on the long time-series land cover classification results. Mangrove habitats increased in Deep Bay from 1924 to 2020, except for a large area decrease from 1954 to 1964 due to the construction of tidal aquaculture ponds. Mudflat areas contributed most to the expansion of mangrove habitats of about 275 ha from 1987 to 2020. During this period, reclamation and urbanization for the construction of the megacity of Shenzhen turned large areas of water and mudflat (about 4000 ha) on the northern shore into impervious surface and urban vegetation. Overall, the landscape pattern of mangrove habitats in Deep Bay showed increasing connectivity and decreasing degree of fragmentation from 1987 to 2020. These changes have significant implications for the ecosystem services, e.g., supporting migratory waterbirds, supported by these wetlands.

Fish habitat use in a Caribbean mangrove lagoon system

One of the most important ecosystem services of mangroves is their role as fish habitat. While this function has been studied in many Caribbean Islands, Indo-West Pacific areas and lagoon systems in the Americas, studies in turbid estuarine lagoon systems in the Caribbean are scarce. We surveyed fish in the Ciénaga Grande de Santa Marta (CGSM), Colombian Caribbean, at five sites which had different mangrove and physicochemical characteristics. Three gillnets, parallel to the mangroves, were set at each site over six sampling cycles (n = 84); one in the mangrove, one further (∼250 m) from the mangrove and a third one furthest from the mangrove (∼400 m). We hypothesized that fish abundance and diversity, would be higher in mangrove habitats compared to mudflats, whereas biomass would be higher away from mangroves. Total fish abundance and juvenile fish abundance differed across habitats and sites, while fish biomass and fish diversity differed across sites, but not across habitats. While mangroves may be critical habitats for fish in the CGSM, mudflats may be of similar importance. Some sites had very high salinity values that together with other anthropogenic activities may limit the benefits of mangrove as critical habitats. The proportion of juveniles (67%) relative to adults of estuarine species is of concern. We recommend urgent implementation of management strategies that focus on maintaining freshwater inputs and mitigate the impact of fisheries the system is suffering.