Mangroves, tidal marshes and seagrasses have experienced extensive historical reduction in extent due to direct and indirect effects of anthropogenic land use change. Habitat loss has contributed carbon emissions and led to foregone opportunities for carbon sequestration, which are disproportionately large due to high ‘blue carbon’ stocks and sequestration rates in these coastal ecosystems. As such, there has been a rapid increase in interest in using coastal habitat restoration as a climate change mitigation tool. This review shows that restoration efforts are able to substantially increase blue carbon stocks, while also having a positive impact on various gaseous fluxes. However, blue carbon increases are spatially variable, due to biophysical factors such as climate and geomorphic setting. While there are potentially hundreds of thousands of hectares of land that may be biophysically suitable for restoration, these activities are still often conducted at small scales and with mixed success. Maximizing potential carbon gains through blue carbon restoration will require managers and coastal planners to overcome the myriad socioeconomic and governance constraints related to land tenure, legislation, target setting and cost, which often push restoration projects into locations that are biophysically unsuitable for plant colonization.

We measured the concentrations of antifouling biocides in sediment, mangrove leaves and seagrasses from Merambong and Tinggi Island, Johor, Malaysia to evaluate their contamination levels. Although the concentrations of tributyltin (TBT) in mangrove leaves in Merambong in 2013 were significantly lower than those in 2012, the Sea-Nine 211 concentration in 2013 was significantly higher than that in 2012, suggesting that the use of antifouling biocides changed from TBT to Sea-Nine 211. The concentration of each BT (butyltin) and PT (phenyltin) in the mangrove area was significantly higher than the corresponding concentration in the seagrass area in Merambong, but the concentrations of Sea-Nine 211, diuron, chlorothalonil, Irgarol 1051 and M1 in seagrasses were significantly higher than those in mangrove leaves. There were differences in the accumulation profiles of OTs (organotins) and alternative biocides between the seagrass shoots and roots. The concentration of OTs in the seagrass roots was almost the same or higher than those in the shoots, whereas those of alternative biocides shows the opposite pattern to the OTs. Significant high relationships were observed between stable carbon isotope (δ13C) and OTs, Sea-Nine 211 and Irgarols in mangrove leaves. The concentrations of these compounds increased along with the δ13C values of the mangroves. These results suggest that mangroves take up the bicarbonate ions and nutrients in sediment and/or seawater through their roots, along with OTs, Sea-Nine 211 and Irgarols which were accumulated in sediment.

Late Holocene relative sea-level reconstructions are commonly generated using proxies preserved in salt-marsh and mangrove sediment. These depositional environments provide abundant material for radiocarbon dating in the form of identifiable macrofossils (salt marshes) and bulk organic sediment (mangroves). We explore if single-step graphitization of these samples in preparation for radiocarbon dating can increase the number and temporal resolution of relative sea-level reconstructions without a corresponding increase in cost. Dating of salt-marsh macrofossils from the northeastern United States and bulk mangrove sediment from the Federated States of Micronesia indicates that single-step graphitization generates radiocarbon ages that are indistinguishable from replicates prepared using traditional graphitization, but with a modest increase in error (mean/maximum of 6.25/15 additional 14C yr for salt-marsh macrofossils). Low 12C currents measured on bulk mangrove sediment following single-step graphitization likely render them unreliable despite their apparent accuracy. Simulated chronologies for six salt-marsh cores indicate that having twice as many radiocarbon dates (since single-step graphitization costs ∼50% of traditional graphitization) results in narrower confidence intervals for sample age estimated by age-depth models when the additional error from the single-step method is less than ∼50 14C yr (∼30 14C yr if the chronology also utilizes historical age markers). Since these thresholds are greater than our empirical estimates of the additional error, we conclude that adopting single-step graphitization for radiocarbon measurements on plant macrofossils is likely to increase precision of age-depth models by more than 20/10% (without/with historical age markers). This improvement can be implemented without additional cost.

Ecological and biogeographic information for marine gastropods has lagged behind taxonomic, molecular and phylogenetic information, limiting understanding of evolutionary processes. We investigated niche separation and speciation in rapinine whelks that represent a rare deep estuarine penetration by muricid gastropods. We studied the genetic and ecological differentiation of four Indothais morphotypes, distributed along a salinity gradient in Brunei (Borneo, South East Asia). Our molecular analyses, based on three mitochondrial genes (COI, 12S rRNA and 16S rRNA) and one nuclear gene (28S rRNA), revealed three species having the following relationship [Indothais rufotincta (Tan & Sigurdsson, 1996), [I. javanica (Philippi, 1848), [I. gradata (Jonas, 1846)]]]. This pattern coincided with their salinity-related distributions, such that I. rufotincta occurred alone in the open coastal waters, and I. javanica and I. gradata extended into the upper estuary. This suggests speciation through divergent selection and local adaptation, specifically synapomorphic low salinity tolerance by I. javanica and I. gradata. The observed intertidal vertical separation where the species co-occur suggests competitive exclusion of the others by the most-recently evolved I. gradata. This species also showed greatest morphological and genetic variation, and unique niche expansion involving feeding on both hard surface and muddy sediment organisms. Our study presents a novel hypothesis for the speciation of these snails.

Sedimentological, geochemical, and paleontological investigations of the coastline of northeastern Oman have provided the authors with an in-depth insight into Holocene sea levels and climate conditions. The spatial distribution and species assemblage of mangrove ecosystems are analyzed. These ecosystems are sensitive to changes in sea level and precipitation and thus reflect ecological conditions. The close proximity to archaeological sites allows us to draw conclusions regarding human interaction with the mangrove ecosystems. Our interdisciplinary inquiry reveals that the mangrove ecosystems along the east coast of Oman collapsed ~6000 cal yr BP on a decadal scale. There is no sedimentological evidence for a mid-Holocene sea-level highstand. The ecosystem collapse was not caused by sea-level variation or anthropogenic interferences; rather, it was the consequence of reduced precipitation values related to a southward shift of the Intertropical Convergence Zone. This resulted in a decrease of freshwater input and an increase in soil salinity. Further, the aridification of the area caused increased deflation and silting up of the lagoons.

To elucidate the details of both the current status of contamination and the accumulation of organotin compounds (OTs) in mangroves in coastal ecosystems, we determined the concentrations of butyltin compounds (BTs) and phenyltin compounds (PTs) in sediment and mangrove leaves collected from mangrove forests in Merambong and Tinggi Island, Malaysia. Butyltins were detected in all sediment samples collected from both regions, whereas PTs were not detected. The levels of tributyltin (TBT) compounds in the sediment samples were lower than those from previous studies conducted in Malaysia and at other sites in South-east Asia. In both Merambong and Tinggi Island, the average proportions of dibutyltin (DBT) and monobutyltin (MBT), which are degradation products of TBT, were ~70%. This result suggests that the input of TBT has decreased in Malaysia. The proportions of DBT and MBT in the sediment from Merambong were higher than those from Tinggi Island. The concentrations of TBT in mangrove leaves from Tinggi Island were significantly higher than those from Merambong. MBT was the most dominant type among the BTs in mangrove leaves from both Merambong and Tinggi Island. The ratios of the BTs burden in mangrove leaves to the BTs concentration in sediment from Merambong and Tinggi Island averaged 3.1 and 6.2, respectively. Among the values of BTs, the MBT values were found to be the highest in both regions.

The lowland area of southern Vietnam contains a high diversity of corticolous, crustose lichens, particularly in the family Graphidaceae. Two species, Acanthothecis verrucosa S. Joshi, Upreti & Hur and Graphis exuta S. Joshi, Upreti & Hur, are described new to science. Acanthothecis verrucosa is characterized by a verrucose, olive green thallus containing irregular to shortly lirellate apothecia, hyaline to brownish proper exciple apically lined by robust periphysoids, muriform ascospores, 30–70 × 15–20 μm, and the presence of psoromic and subpsoromic acids. Graphis exuta is characterized by a smooth, greenish white thallus, simple lirellae lacking thalline margin, entire labia coarsely white pruinose towards slit, muriform ascospores, 20–35×10–13 μm, and norstictic acid in the thallus. A new name, Acanthothecis yokdonensis S. Joshi & Hur, is proposed here for the species Acanthothecis salazinica S. Joshi & Hur, a later homonym of A. salazinica van den Boom & Sipman. In addition, 34 species from Vietnam are newly reported. A world key to the group of Graphis species characterized by short, simple and sessile lirellae lacking or with basal thalline margins (nuda-morph) is presented.

The aim of this paper is to evaluate the compatibility between the Holocene relative sea-level (RSL) curves proposed for the Brazilian littoral and mangrove dynamics along a fluvial valley in the state of southern Bahia. This was done integrating geomorphological, sedimentological, palynological, and stable isotopic data from two cores collected at the mouth of the Jucuruçu River and at a site 23 km inland, near the city of Prado, northeastern Brazil. Core PR07, sampled from a fluvial plain at about 4.5±1 m above the RSL, reveals mangrove pollen (5–20%) and estuarine/terrestrial organic matter (δ13C=~–25‰, C/N=7.3–67) between 4.5 m (~7400 cal yr BP) and 1.75 m depth (~5350 cal yr BP). Core PR11, sampled from a mangrove tidal flat, also revealed mangrove pollen taxa (5-28%) since 660 cal yr BP. Core PR07 indicated absence of mangrove pollen and increase of sedimentary organic matter sourced from terrestrial C3 plants (δ13C=~–27‰, C/N=22–159) during the last 5350 cal yr BP. Probably, the changes in vegetation and sedimentary organic matter identified in core PR07 were caused by the combined effects of the RSL fluctuations, with a highstand at about 5350 cal yr BP of 2.7±1.35 m, and changes in fluvial discharge.

High abundances of mangrove pollen have been associated with transgressive cycles on tropical margins, but the detailed relations between systems tracts and the taphonomy of the pollen are unclear. We report here the occurrence and high abundance of Rhizophora pollen, in association with taraxerol, a Rhizophora-sourced biomarker, from a high-resolution Congo fan core covering the last deglaciation. An age model based on 14C dates enables the temporal changes in taraxerol content and the percentage frequencies and flux (pollen grains (pg) cm–2 (103 yr)–1) of mangrove pollen to be compared quantitatively with the lateral rate of transgression across the flooding surface (derived from glacio-hydro-isostatic model output and the bathymetry of the margin). Rhizophora pollen concentrations and taraxerol content of the sediment are very strongly positively correlated with the lateral rate of transgression and indicate, independently of any sequence stratigraphic context, that mangrove pollen spikes are associated with the transgressive systems tract rather than the highstand systems tract or maximum flooding surface. Lower-resolution longer-term records from this margin indicate an association between taraxerol concentrations and transgressive rather than regressive phases. The flux of these materials to the Congo fan is interpreted as a function of the erosion of flooded mangrove swamp on the shelf and less importantly, changing extent of mangrove habitat, during sea-level rise. Congo River palaeoflood events also result in reworking of mangrove pollen and supply to the fan, but this mechanism is subdominant. Rhizophora pollen has been underestimated in many palynological studies undertaken on cores from the African margin because of inappropriate sieve mesh size used during laboratory preparation.

This study examines a sediment core (SR-63) from a mangrove ecosystem along the Sibun River in Belize, which is subject to both changes in sea-level and in the characteristics of the river's drainage basin. Radiocarbon dates from the core show a decreased sedimentation rate from ~ 6 ka to 1 cal ka BP and a marked change in lithology from primarily mangrove peat to fluvial-derived material at ~ 2.5 cal ka BP. Changes in the sedimentation rates observed in mangrove ecosystems offshore have previously been attributed to changes in relative sea-level and the rate of sea-level rise. Pollen analyses show a decreased abundance of Rhizophora (red mangrove) pollen and an increased abundance of Avicennia (black mangrove) pollen and non-mangrove pollen coeval with the decreased sedimentation rates. Elemental ratios ([N:C]a) and stable isotope analyses (δ15N and δ13C) show that changes in the composition of the organic material are also coeval with the change in lithology. The decrease in sedimentation rate at the site of core SR-63 and at offshore sites supports the idea that regional changes in hydrology occurred during the Holocene in Belize, influencing both mainland and offshore mangrove ecosystems.

Ucides cordatus is a semi-terrestrial crab and key species endemic to mangrove areas of eastern Americas. In North-eastern Brazil this crab holds a major socio-economic function for artisanal fisheries, as in the São Francisco River Estuary (10°30′27″S 36°23′45″W). Nevertheless, decreases in this species’ stock have been reported since 2000, requiring assessments of the crab population for conservation and management purposes. This study aims at assessing the population status and the fishery potential of this species in the mangroves of this estuary and suggests strategies for its fishery and conservation, according to the guidelines of the National Management Plan for U. cordatus Sustainable Use. Six different sites established in 30 km2 of mangroves were sampled, with the density of U. cordatus burrows estimated to evaluate the population structure using the measure of burrow diameters. Results show that the crab mean burrow size was 56.82 (±12.2) mm and that the medium-size crabs (40–70 mm) are the most abundant. The total mean crab density was 1.2 crabs m−2, from which the density of crabs in commercial size (0.85 ± 0.55 crabs m−2) was significantly higher than those in non-commercial size (0.35 ± 0.21 burrow m−2). These mangroves showed a high potential for the crab fishery, with an immediate extractive potential (IEP) of 71.2% and future extractive potential (FEP) of 28.8%. Nevertheless, a lower crab density, probably due to high crab mortality, mangrove deforestation for shrimp farming and high fishery pressure, is a limiting factor for local fishery. We conclude that mangrove areas more appropriate for U. cordatus fishery (extractive areas) show higher mean crab size, IEP and density of commercial crabs, wherein a fixed exploitation rate or/and a fixed escapement rule should be considered. Exclusion areas, intended for the conservation, show lower values of these population parameters and higher FEP, wherein the fishery should be prohibited. These management strategies should also be considered in other Brazilian mangrove areas showing similar crab population structure, thus contributing to the National Management Plan for U. cordatus Sustainable Use.

Ra’s al-Hamra 6 (RH-6) is one of the earliest stratified archaeological sites along the eastern littoral of the Arabian Peninsula. This shell midden was radiocarbon dated to the 6th–5th millennium cal BC, but the majority of the dates were obtained before the advent of accelerator mass spectrometry (AMS) 14C dating and suffer from large uncertainties. In addition, most of these dates were obtained on marine and mangrove shells and required correction for local variations from the global average marine 14C reservoir age (MRA). This proved difficult because no consensus value exists for this period in the area. Recent excavations at RH-6 offered the opportunity to redate this important site in order to precisely determine its occupation history and later use as a graveyard, and establish the marine reservoir effect for this time period. Thirty-eight samples of charcoal, shells, and human bone apatite were selected for 14C dating. Bayesian modeling of the 14C dates suggests that the formation of the shell midden spanned ~1 millennium, between the mid-6th and the mid-5th millennium cal BC. Positive and consistent ΔR values were calculated throughout the entire sequence, ranging from 99±27 to 207±43 14C yr. At the beginning of the 4th millennium cal BC, RH-6 was used as a graveyard, as suggested by the 14C dating of a shell in strict association with an individual buried at the surface of the site. 14C dating of human bone apatite allowed us to calculate that 89% of this individual’s diet derived from marine resources. This finding confirms previous observations showing the overwhelming presence of marine and mangrove-dwelling species in the faunal and charcoal assemblage, and implies a low mobility, or mobility restricted to the coast for this population during the 4th millennium cal BC.

A mangrove forest can harbour several macroalgal assemblages growing on pneumatophores, roots, stems and other hard substrates. These algae belong to various genera, most typically Bostrychia, and form a community called the Bostrychietum. This study describes the fauna associated with the Bostrychietum and the effect of emersion time on the community. Seasonal samples were collected from pneumatophores on an island in Araçá Bay in 2012, in two areas, one on the border of the island and one inland. Each pneumatophore was considered a sample. The border samples, with a shorter emersion time, contained a richer algal flora associated with pneumatophores, and fauna with species of varied dietary habits. The inland samples, with a longer emersion time, contained only two algal genera and fauna species comprised mostly of omnivorous amphipods and desiccation-resistant detritivorous species. Macrofauna diversity and richness varied over time and were lower in spring. Therefore, the emersion time of the Bostrychietum and the period of the year affect the community structure, for both the macroalgae and the associated fauna.

Mangrove ecosystems are unique fish habitats because they provide shelter and food for juvenile fish. Hara Biosphere Reserve (HBR) is a coastal region in the Khuran Strait situated in the northern part of the Persian Gulf. Mangrove forests of this region are important for people's livelihoods. Moreover, shallow water, coastal wetlands and other estuarine habitats with very restricted water flow and nutrient rich areas provide shelter to young fish. The results of monitoring and Evaluation for Fishing Communities in 2008 showed that there are a total of 43 families of fish that were associated with HBR. Among 44 families Leiognathidae, Clupeidae, Carangidae and Mugilidae families are the most abundant fish species in the area. However, most popular fish were in the juvenile stage of their life cycle. Because of the rich diversity of fish in coastal waters, the lives of a large proportion of people living in this region are directly dependent on fishing. Results have shown that although there is no considerable difference in fish diversity among the different fishing methods, a clear distinction between the fishing methods and the weight of fish is obvious.

This study evaluated the decomposition process of leaf litter from the main Brazilian mangrove species Avicennia schaueriana, Laguncularia racemosa and Rhizophora mangle. Senescent leaves were collected, dried and placed in nylon bags with different mesh sizes (fine: 2 × 2 mm and coarse: 8 × 8 mm). The bags were distributed over the sediment, and replicates of each species and mesh size were collected periodically over 4 months. In the laboratory, the dry weight of the samples was measured, and the decomposition coefficient (k) for each species and mesh size was obtained over time. All species showed a rapid decomposition rate at the beginning of the experiment, followed by a slower but steady rate of decomposition over time. The rate of leaf litter decomposition was highest in A. schaueriana, intermediate in L. racemosa and lowest in R. mangle. The difference was mainly linked to the activity and abundance of detritivores, together with the different litter quality of the species, which determined their palatability and probably influenced the decomposition process.

The population structure and biological aspects of the shallow water mysid Mesopodopsis orientalis were studied in the Versova mangrove, Mumbai, India. The monthly collections ranged from 0–2104 ind.m−3with an average of 78.6 ind.m−3. The sampled population was found in a wide range of temperature (25.5°C to 34°C) and salinities (20.3 to 37.1). Carapace length significantly correlated with total body length (P < 0.01). Mesopodopsis orientalis breed throughout the year but there is a seasonal variation in the intensity of breeding. The size of mature males and females was at maximum during the post-monsoon period. The species produced more than one generation per year and the number of embryos carried by a single female ranged from 6–18, and was correlated with female body length (R2 = 0.69). Egg size varied between 0.32 and 0.45 mm, with no correlation with length of females.

This study was carried out in order to provide basic information on the population ecology of the crab Sesarma rectum in the Ariquindá River mangrove, Tamandaré, State of Pernambuco, Brazil. The population was analysed with regard to the following aspects, in particular: the size-class frequency distribution of carapace width (CW), mean body size (CW) of males and females, morphological sexual maturity, sex-ratio, reproductive period, and recruitment. Samples were collected monthly from April 2008 through to March 2009; the crabs were collected manually, with a capture effort by one person for 30 minutes, during low tide. The specimens obtained were measured for CW, length of the propodus of males, and abdomen width of females; and the sex and ovigerous condition were noted. Altogether, we obtained 511 specimens (132 juvenile and 137 adult males, and 171 juvenile and 71 adult females, of which 32 were ovigerous). The median CW of males (16.15 mm) was significantly larger than that of females (13.82 mm) (P < 0.05). The size at morphological sexual maturity was 15.73 mm in males and 16.71 mm in females. The sex-ratio for the total of specimens analysed was 1.11:1 (male:female) (P > 0.05). The sex-ratio by size-class showed an anomalous pattern, with a greater abundance of males in the larger size-classes. The reproductive period was continuous and the highest frequency of ovigerous females was recorded in the spring and summer. The major pulse of recruitment occurred during autumn and winter, which is related to greater reproductive activity during the warmer months of the year.

Basic information required to conserve wild tigers Panthera tigris is lacking for the Bangladesh Sundarbans. The objectives of this study were therefore to estimate tiger home range size and obtain information on movement. Two adult female tigers were captured in the south-east of the Sundarbans and fitted with global positioning system collars. Mean home range sizes for the two tigers estimated with 95% minimum convex polygon and fixed kernel methods were 12.3 and 14.2 km2, respectively. A mean female home range size of 14.2 km2 would indicate a density for the south-east Sundarbans of seven adult females per 100 km2. The maximum distance moved by a tiger in 1 day was 11.3 km. Although preliminary these home range estimates indicate that the Sundarbans of Bangladesh has good quality tiger habitat relative to other tiger landscapes, highlighting the value of this mangrove ecosystem for the survival of this Endangered species.