Search

In a tropical coastal environment, mangrove ecosystems store large amount of atmospheric carbon in biomass and soil. West coast of India host 29% of the mangrove ecosystems of the country. Putting aside the few scientific studies about the Indian mangroves system, there exist gaps in our scientific knowledge of Blue Carbon domain. This study aims to quantify the ecosystem carbon stocks potential and community structure of mangrove vegetation/ ecosystem species of Vypin– Cochin, a coastal region of the Southwest coast of India. The information on species-specific carbon storage will benefit to choose best species in the afforestation and conservation initiatives. Distribution, community structure and carbon pools of above and below ground biomass of the study area were assessed. From the analysis, it is evident that the amount of carbon stored in mangroves varies according to species, functional attributes (basal area, DBH, mean height etc.) and region. Avicennia officinalis, Rhizophora mucronata, Acanthus ilicifolius, Acrostichum aureum, Bruguiera cylindrica and Sonneratia caseolaris are the mangrove species observed from the study area. As per the community structure assessment, A. officinalis showed large number, frequency, density, and evenness. While considering biomass, R.mucronata species possess high value. The mean overall above ground biomass of the region was 69.55 ± 80.38 t ha−1. Ecosystem carbon stock of the area ranges from 17.7–138.8 with an average of 54.3 ± 36 t ha−1. Therefore, the findings described will serve as a baseline on carbon stock and mangrove stand structure of the region and their role in Blue Carbon dynamics of the Southwest Coast of India.

Mangroves adaptive plasticity in the changing environmental conditions is of vital importance for conservation management. Genetic diversity of mangrove brings about adaptive plasticity, enabling a species to cope with different habitat conditions. The Sundarbans of Bangladesh is the largest coastal wetland and mangrove forest with diversified habitat conditions that support a wide diversity of flora and fauna. Avicennia officinalis L. is the pioneer species in mangrove succession in the low-salinity, medium-salinity and high-salinity zones of the Sundarbans. Adopting RAPD-PCR analysis, the genetic diversity of A. officinalis was studied to explore the ecotypes of this species in the Sundarbans. The genetic distances of A. officinalis between the low-salinity and medium-salinity zones (0.50) and between the low-salinity and high-salinity zones (0.52) are significantly (p

The mangroves of Andaman and Nicobar Islands are considered as one of the finest vegetation in India with respect to species composition as well as structure. However scientific information on the influence of edaphic attributes on the structure of Andaman mangroves are lacking. Hence, we assessed the floristic composition, structural attributes, zonation pattern and its relation to edaphic variables of mangroves of the Andaman islands. Quadrat method was employed to estimate the different structural variables and multiple regression analysis to explain the influence of edaphic variables over structural attributes. Floristic analysis of 420 quadrats (10x10m) revealed a mixed species composition with 28 true mangroves in Andamans, of which Avicennia officinalis, Rhizophora apiculata, and R. mucronata were designated as the most important species based on the importance value index. Stem density varied from 133 to 14,000 ha−1 and individual basal area 0.07–78.75 m2 ha−1, further, most of the mangrove habitats showed very high stand basal area. Relatively higher Maturity Index Value was observed indicating high structural maturity in Andamans. Species zonation pattern typically varies based on the tidal inundation. Multiple regression analysis revealed the importance of soil pH, silt, total carbon, total Nitrogen and salinity in shaping the structure of Andaman mangroves. The data evolved in the study would be valuable in the site-specific management and conservation approaches of mangroves in Andamans.

Urban development is driving the loss and subsequent fragmentation of mangrove forests in Penang, Malaysia. However, little research has focused on the implications of urbanization onto the biodiversity within mangrove forests. This study investigates and compares both vegetation and crab assemblages between urban and rural mangrove forests. Collectively, 5853 trees were recorded including 15 species from six families: Acanthaceae, Arecaceae, Lythraceae, Malvaceae, Meliaceae, and Rhizophoraceae. Avicennia marina accounted for 88.6% of all trees in the study and held the highest species importance (IV). Although the total number of mangrove tree species varied significantly between urban (14) and rural (7) mangrove forests, the mangrove forest structure based on IV did not vary significantly. In total, 633 crabs were recorded comprising 13 different species from three superfamilies: Grapsoidea, Ocypodoidea, and Paguroidea. Crab species richness did not vary between urban and rural sites, but the biomasses of five and the densities of four crab species varied significantly. Redundancy analysis (RDA) indicated that land use, salinity, and abundance of Avicennia officinalis can best describe the distribution of crab species (r2 =32.7). This study indicates that smaller fragmented urban mangroves at the east coast of Penang have a relatively high tree and crab diversity and are worth protecting, in addition to the larger mangrove forests on the west coast. The preservation of small yet interconnected mangrove sites could be critical to the recruitment of their flora and fauna and should be considered in decision-making processes.

The ability of mangrove trees to reproduce and disperse in highly dynamic tidal environments is reflected in the contemporary genetic diversity and structure of their populations. Resilience and establishment may occur through either local recruitment (propagule pool model) or over longer distances with mixed origins (migrant pool model), thereby affecting the connectivity between natural populations. Anthropogenic activities such as encroachment and fragmentation or from mitigating reforestation could cause strategy switches and thus the connectivity and genetic structure of populations. In this study, we considered Avicennia officinalis, a dominant component of the Sundarban mangrove forest in Bangladesh to estimate dispersal dynamics over various distances within estuaries. A total of 423 individuals of A. officinalis, distributed over thirteen sites in the Sundarbans were sampled at both large and fine-scaled spatial level, the latter for comparison of natural and dense with fragmented sites. Up to 62 alleles showed a comparable level of allele diversity and gene diversities at both juvenile and adult life stages, assuming overall high levels of outcrossing. Significant inbreeding levels and high kinship values were solely observed at a reforested A. officinalis site. Genetic variables revealed high levels of connectivity between sites at close vicinity, with only a weak structure over larger geographic distances, between natural core Sundarban and coastal edge populations. Kinship coefficients were mostly low though significant up to several kilometers along estuarine branches, thereby suggesting propagule dispersal beyond each site. A fine-scaled analysis of kinship levels estimated for fragmented and natural forest plots along both sides of a river revealed that fragmentation induced higher kinship levels over 25–50 m distance, whereas dense natural populations were composed of less related individuals at shortest distances. A. officinalis populations might stay resilient through a mixture of unrelated propagules, clearly adhering a migrant pool model in natural sites and propagule pool model in fragmented sites. A poor gene diversity of planted trees might jeopardize the sustainability of mangrove plantation practices. Furthermore, high levels of diversity and connectivity indicated that the core Sundarban populations are a relevant source of germplasm in afforestation programmes.

In a mangrove environment, several groups of organisms are symbiotically associated with pneumatophores (aerial roots). But whether these organisms are exclusively found in this habitat (uniqueness) or accidentally settled here from water or sedimentary habitat, is not clearly understood. This hampers our understanding of their functional ecology. Hence the present study aimed to characterise the epibiotic microalga and meiofauna from the pneumatophores of mangrove Avicennia officinalis . To determine the habitat influence, these communities were also compared with those found in water and sedimentary habitat. Four estuarine mangrove sites represented by brackish water (salinity varying from 5 to 12) and located at different spatial scales (5–50 km distance) were chosen to determine whether these communities are consistent or vary with sites. Overall, the microalgal community was found to vary both among the habitats as well as sites. In the pneumatophore habitat, several tychoplanktons such as Coscinodiscus, Thalassionema , Cyclotella, Fragilariopsis, and Biddulphia were observed instead of benthic ones. These diatoms are planktonic genera and might have settled on pneumatophores from the water column. The observed variability in the microalgal composition among the sites is possibly due to predatory interactions or the dominance of particular species of macroalga that govern the diatom community. On the other hand, among the meiofaunal community, diptera, halacarida, tanaidacea, and foraminifera were mainly found in the pneumatophore habitat than in the sediment. Because pneumatophores either provide refugee to meiofauna against predators or are saturated with oxygen that meiofauna can utilize for respiration. Pneumatophores were also found to harbour several rare (abundance

Variations in stem biomass and carbon density in 12 mangrove species were studied to understand the potential of carbon storage in the live biomass of Bhitarkanika mangrove ecosystems, South-East Coast of India. The results highlighted significant inter-species variations (p C org / N tot ratios followed by Heritiera fomes. Further, the higher carbon sequestration capacity of these two mangrove species was confirmed through Principal Component Analysis (PCA). C org , C org / N tot and cellulose/protein ratio were strongly associated with the wood density of the studied mangrove species. Mangrove stem diameter (at breast height; DBH), wood density and tree height were used to estimate the above-ground biomass of all the species, which showed remarkably higher biomass for Avicennia officinalis. Possible adaptation of these species under extreme environmental conditions in addition to variations in vessel wall thickness caused by differential carbon fixation and storage in the form of biomass could explain the variability in elemental properties of mangrove stem wood. Heritiera littoralis and Kandelia candel with relatively higher lignin to cellulose content showed greater potentials to sustain biotic and abiotic stresses and indicated higher carbon sequestration as recalcitrant biomass. The lowest carbon density and highest ratio of cellulose/lignin in the Sonneratia apetala and Sonneratia caseolaris species indicated faster plant growth compared to the other studied species. FTIR analysis evidenced that the increase in the 1728–1733 cm −1 band height assigned to cellulose and decrease in the 1517–1519 cm −1 band height assigned to lignin.

The genetic assembly of Avicennia marina (Forsk.) Vierh, Avicenniaceae within and between the three natural mangrove forests of Kerala coast belonging to the districts of Kochi, Kozhikode and Kannur was investigated using Inter Simple Sequence Repeat (ISSR) markers to provide coherent scientific conservation practices. The ten selective ISSR primer combinations of 60 genotypes of Avicennia marina ensured a total of 171 bands of which 84.5% were polymorphic. Gene diversity index H varied from 0.142 Kochi to 0.195 Kozhikode. The mean gene diversity HS was 0.169 and the total gene diversity HT was 0.262 which showed a moderate level of genetic diversity in the studied population. The mangrove Avicennia marina populations showed large genetic difference GST = 0.3849, indicating that 38% of the total genetic diversity was among the populations and the rest 62% resides within the population. The gene flow estimates Nm = 0.79 shown that natural mangroves of Kerala are in the course of differentiation due to genetic drift. We investigated the genetic distinctiveness of taxonomically confusing species, Avicennia marina and Avicennia officinalis, and resulted in clear demarcation between the two. There is a significant correlation between dendrogram and PCoA designated that extensive distant spreading of seeds between populations of Avicennia marina is comparatively low. The genetic study contributed relatively high diversity and strong differentiation across the three eco-geographic locations. The best remedy to preserve coastal mangrove species like Avicennia marina is to plant the identical species in its respective habitat. Launch, on-site protection zones to safeguard the species and to decrease the impact of human activities would allow its habitats to increase in size through natural regeneration.

Background The article presents the first estimates of biomass and productivity for mangrove forests along the Oligohaline zone of the Sundarbans Reserve Forest (SRF), Bangladesh. This study was conducted overone year from March 2016 to April 2017. Stand structure, above and below-ground biomass changes, and litterfall production were measured within a 2100 m2 sample plot. Methods All trees in the study plots were numbered and height (H) and diameter at breast height (DBH) were measured. Tree height (H) and DBH for each tree were measured in March 2016 and 2017. We apply the above and belowground biomass equation for estimating the biomass of the mangrove tree species (Chave et al. Oecologia 145:87−99, 2005; Komiyama et al. J Trop Ecol 21:471–477, 2005). Litterfall was collected using 1-mm mesh litter traps with collection area of 0.42 m2. Net Primary Production (NPP) was estimated by the summation method of Ogawa Primary productivity of Japanese forests: productivity of terrestrial communities, JIBP synthesis (1977) and Matsuura and Kajimoto Carbon dynamics of terrestrial ecosystem: Systems approach to global environment (2013). Results Heritiera fomes has maintained its dominance of the stand and also suffered the highest tree mortality (2.4%) in the suppressed crown class. The total above-ground biomass (AGB) and below-ground biomass (BGB) of the studied stand was 154.8 and 84.2 Mg∙ha−1, respectively. Among the total biomass of the trees, 64.8% was allocated to AGB and 35.2% to BGB. In case of species-wise contribution of biomass allocation, Avicennia officinalis showed the highest score and Aglaia cucullata the lowest. Mean annual total litterfall was 10.1 Mg∙ha−1∙yr−1, with the maximum litterfall in winter or dry season and late summer or rainy season. The mean AGB increment and above-ground net primary productivity (AGNPP) were 7.1 and 17.2 Mg∙ha−1∙yr−1, respectively. Total net primary productivity (NPP) was estimated to be 21.0 Mg∙ha−1∙yr−1 over the observed period. The results in the Sundarbans mangrove forests exhibited that mangrove communities with similar height and diameter produced different biomass production with the different basal area. The present analysis revealed that the root biomass was large enough and the mean ratio of above−/below-ground biomass was estimated to be 1.84. Conclusions Mangrove communities growing at the oligohaline zone of the Sundarbans, Bangladesh showed high biomass and net primary production indicating their ecological and conservation significance that may be considered in future decision making process for the area as well as in understanding the role of Sundarbans mangrove forest on mitigating the effect of global warming.

Mangrove pneumatophores (respiratory roots) form a unique habitat about which very little ecological information is available. In this study, epiphytic diatoms on the pneumatophore surface of Avicennia officinalis (L.) were investigated with a focus on their seasonal and vertical distribution. The results indicated that among the seasons, highest diatom abundance was observed in monsoon. Vertically, maximum abundance was observed on 0–5 cm of the pneumatophore during post-monsoon and pre-monsoon and then gradually decreased upwards, but during monsoon, 5–10 cm section hosted maximum abundance. There was a seasonal and vertical variation on the diatom abundance and their interactive effect. This is because diatoms probably avoid the basal section (0–5 cm) of the pneumatophore during monsoon due to excessive sediment burial caused by intense riverine flux and settlement of suspended material. Overall it was found that vertically, diatoms (>70%) are mainly concentrated on the lower 0–10 cm of the pneumatophore, probably because this section remains moist during emersion period (low tide). Among the diatoms, Melosira nummuloides and Bacillaria paradoxa exhibited dominance during the monsoon, whereas Thalassiosira spp., Navicula spp., and Nitzschia spp.were prevalent during post- and pre-monsoon. To the best of our knowledge, this is the first study describing the composition of epiphytic diatoms from the pneumatophore surface of A. officinalis. Keeping in mind that these aerial roots together greatly enhance the surface area for attachment of epiphytic diatoms, their cumulative primary production would probably surpass that of mangroves on a quantitative basis and needs future investigation.

The purpose of this work was to assemble information with which to help identify and select mangrove species most likely to be useful and locally acceptable for use in transforming the dominant current non-mangrove shrimp culture practice in Bangladesh towards more sustainable shrimp silvo-aquaculture in the coastal regions of the country. We reviewed current mangrove use in the extensive aquaculture setting, compiled published evidence on mangrove properties and characteristics that influence their suitability for such use and assessed farmer preferences of the various species. Thirteen mangrove species (all of which are available in Bangladesh) were documented as being used in silvo-aquaculture system in the tropics. Followed by these already “established” mangrove species, Aegialitis rotundifolia, Heritiera fomes and Lumnitzera racemosa could be enlisted as additional “optional” mangrove species to consider, while Ceriops decandra, Excocaria agallocha and Phoenix paludosa were found to be unsuitable for silvo-aquaculture. Based on their experience and indigenous knowledge on mangroves, shrimp farmers ranked (in declining order of preference) Sonneratia apetala, S. caseolaris, Avicennia officinalis, Nypa fruticans, Bruguiera sexangula, Heritiera fomes, and also, the mangrove-associate wild rice species Oryza coarctata as the most suitable species to be used for promoting silvo-aquaculture in the coastal areas of Bangladesh. Thus, the focus group interviews with the farmers not only identified which mangroves enjoy most local support for use in transforming current shrimp culture towards more sustainable shrimp silvo-aquaculture but also provided additional leads for species interesting to further investigation into their suitability for silvo-aquaculture.

This study shows results on litterfall dynamics contributing to Net Primary Productivity (NPP) and phenology in three major mixed mangrove habitats in Cochin estuarine system, south-west coast of India. Eleven true mangrove species and three mangrove associates formed the plant biomass where Avicennia officinalis was abundant in Site 1, Excoecaria agallocha in Site 2 and Avicennia officinalis , Rhizophora mucronata were abundant in Site 3. Total tree density varied from 11760 stems ha −1 in Vypin Island (Site 2); 11440 stems ha −1 in Mangalavanam Bird sanctuary (Site 3) and 7680 stems ha −1 , Aroor (Site1). The average stands basal area of the three mangrove habitats were 75.54, 54.85 and 103.26 m 2 ha −1 . The mean annual litterfall production in Cochin mangroves was 16.57±6.58 t ha −1 y −1 in which leaves (53.90%) contributed more followed by flowers, propagules (28.66%) and twigs (17.44%). The spatial variability in litterfall recorded highest in lower latitudinal mangrove habitat, Site.1 followed by Site 2 and Site 3 (2413.36 ± 873.72, 1295.65 ± 401.09, 1263.28±255.28 g DW m −2 y −1 ). Site differences in litter production were statistically significant (one-way ANOVA p 0.001 for total litterfall and p 0.05 for litter components) between the three mangrove habitats. Litter components and total litterfall showed significant seasonality ( p 0.001 ). Highest litterfall was recorded in pre-monsoon period followed by post-monsoon and least in monsoon period. The temporal trend of litterfall was explained through rainfall and mean atmospheric temperature and a negative correlation was there to rainfall during the period. The mean carbon content in the litterfall was estimated as 42.96% of the dry weight and the primary productivity through litterfall in the study area was estimated to be 7.12±2.81 t C ha −1 y −1 . This will act as the major source of carbon input to the mangrove ecosystem and surrounding coastal ecosystems and in turn reflected in NPP.

There are few studies that dealt with species preference in seedling predation by sesarmid crabs in mangrove forests. We investigated predation preference of the sesarmid crab Neosarmatium malabaricum to the seedlings of Aegiceras corniculatum, Avicennia officinalis, Excoecaria agallocha and Rhizophora mucronata in Kunhimangalam mangrove forest in Kerala. Enclosure-exclosure experiments showed that the crab preferred seedlings of E. agallocha the most and that of R. mucronata the least. Reason for this preference was the cumulative effect of morphological and chemical factors of these seedlings. Morphological factors negatively and chemical factors positively influenced the predation preference. Species preference in seedling predation could be inversely proportional to relative abundance and density of saplings. Saplings of the most preferred A. corniculatum and E. agallocha registered low density, and the least preferred R. mucronata and A. officinalis recorded high density in Kunhimangalam mangrove forest. Species preference exhibited by N. malabaricum in seedling predation has been reflected in sapling density and composition. So, this preference can possibly influence the future forest composition.

The objective of this present attempt was to investigate the relationship between leaf quality and level of herbivory at study site during August 2010–July 2011. Total amino acids with a maximum of 9.47 mg g −1 during February 2011 in Rhizophora mucronata and a minimum of 4.671 mg g −1 in May 2011 in Avicennia officinalis were noticed. Tannin was maximum (6.844 mg g −1 ) during April 2011 and minimum (0.667 mg g −1 ) in July 2011 in A. officinalis . Total nitrogen showed a maximum of 9.851 mg g −1 during February 2011 in R. mucronata and a minimum of 2.158 mg g −1 in February 2011 in A. officinalis . Total sugars registered a maximum of 4.075 mg g −1 during March 2011 in A. officinalis and a minimum of 0.063 mg g −1 in March 2011 in R. mucronata . Total phosphorus recorded the maximum (4.321 mg g −1 ) during November 2010 in R. mucronata and minimum (0.258 mg g −1 ) during May 2011 in A. officinalis . Potassium content was maximum (3.710 mg g −1 ) during October 2010 in R. mucronata and minimum (0.039 mg g −1 ) in July 2011 in A. officinalis . These data suggest that artificially developed mangrove ecosystems may be an adaptive mechanism related to nutrient conservation, and that it is associated with mangrove survival in phosphorus-deficient soil rather than an adaptation to herbivory.

The Sundarbans, the largest mangrove forest in the world and a UNESCO world heritage site has been facing increasing pressure of habitat destruction. Yet, no study has been conducted to test how human disturbances are affecting plant-pollinator interactions in this unique ecosystem. Hence, we aimed to provide the first insight into the impact of habitat loss and human disturbances on the pollinator communities in the Sundarbans. We selected 12 sites in the North-Western region of the Sundarbans, along a gradient of decreasing habitat loss and human activities from forest fragments near human settlements to continuous pristine forest, where we studied insect pollinators of two mangrove plant species, Acanthus ilicifolius and Avicennia officinalis. Our results show that different pollinator groups responded to the disturbance gradient differently. For example, the abundance of Apis dorsata, one of the three local species of honey bees, increased gradually from the village area towards the deep pristine forest. On the other hand, A. cerana and A. florea were found in the village sites and completely absent in the deep forest. Although pollinator community composition changed along the disturbance gradient, their efficacy in pollination did not seem to be significantly affected. However, lower plant diversity and low understory plant cover in the forest patches nearby the village indicated that human disturbances not only affected pollinator community composition but also played a major negative role in the regeneration of the forest. Our study provides first insights into plant-pollinator interactions in the Sundarbans and demonstrates that more research is needed to imply conservation strategies for this unique habitat.

The forest structure and its relation to environmental parameters of Sundarbans, largest mangrove habitat in India, are presented. Quadrat method was used to analyze the vegetation-environment interaction and structural maturity of mangroves. Floristic studies revealed twenty-seven mangrove species including the critically endangered Sonneratia griffithii and endangered Heritiera fomes. Based on Importance Value Index, Avicennia marina, Excoecaria agallocha, Avicennia officinalis and Avicennia alba were designated as the most important species. Higher diversity indices were observed (Shannon index, ranged from 4.2-1.8; Pielou’s index, 0.96-0.91) revealing greater species diversity and even dispersion of mangroves in Sundarbans. Stem density varied from 133 to 19333 ha−1 and individual basal area 0.4 to 13.4m2ha−1. A very low Maturity Index Value was recorded indicating a low degree of structural maturity. Most of the vegetation parameters (density, species diversity index, β diversity) and few of the edaphic parameters (pH, grain size, total carbon) were found to be in better condition; however, salinity showed significant negative correlations with vegetation characteristics. The study revealed a mixed species composition with intermediate structural development indicating a growing forest in Sundarbans. The data evolved in the study would be fundamental in site-specific management and conservation efforts of mangroves in this world heritage site.

The Ganges Delta and Sundarbans comprise the largest continuous mangrove area in the world. These mangroves are subjected to high riverine and tidal dynamics, and the coastline irregularity is characterized by many north-to-south oriented rivers that may hamper dispersal of mangrove propagules. Whereas connectivity levels and resulting population genetic structure often can be explained by ocean currents, other factors may control estuarine-scale mangrove genetic patterns and limit gene flow even between sites in close geographic proximity. We investigated whether the complex estuarine coastline in the Ganges Delta and Sundarbans shaped the genetic structure of Avicennia officinalis populations across regions and rivers at various distances (ca. 1 to 265 km). Using nine microsatellite loci, 433 individuals from 14 populations revealed predominant outcrossing and a high level of genetic variation when compared to other Avicennia species. A moderate but significant level of differentiation was detected among populations (F ST = 0.09), and a principal coordinate analysis clearly separated populations of the Chittagong coastline from the Sundarbans. An individual-based Bayesian analysis also indicated those two gene pools. Genetic distances across the whole region could best be explained by cumulative river width and geographical distance separating the populations. Within the Sundarban region, the low genetic differentiation of A. officinalis populations indicated a continuous distribution model with a smooth isolation-by-distance that gradually increased across large rivers shaping the genetic structure of A. officinalis in the Ganges Delta. These findings indicated that in addition to geographical distance, rivers might act as physical barriers, affect gene flow and shape genetic connectivity. This and detailed population genetic information should be incorporated into the ongoing afforestation or restoration strategies in and outside of the Sundarbans mangrove forest.

Mangroves are the plants adapted to strident environment with unvarying inundation of the soil and extremely diverse salinities, habitual in river banks, sand flats and coastlines of the tropics and subtropics of the world. Mangrove vegetation in six geographical regions of Kollam on the Southwest coast of India was selected to study the phytosociological characteristics and diversity indices. We analysed the pattern of mangrove species diversity, density and basal area and similarity parameters. Totally, 12 species of mangroves belonging to 8 genera and 6 families were identified; Rhizophoraceae and Avicenniaceae were the most dominant group represented. Highest density was recorded for Avicennia officinalis (3760stems/ha), followed by Avicennia marina (3721stems/ha). Avicennia officinalis is the most common mangrove counted with the highest Important value index (IVI) and Relative IVI; 64.19 and 21.40 respectively. Shannon- Weiner Index of diversity ranged from 2.002 to 3.11; species richness from 0.429 to 1.033 and the similarity in floral composition varied from 0.33 to 0.66. The sites selected were distinct from one another and the species diversity varied from one place to another; influenced by the climatic, biotic, anthropogenic stresses.

The Sunderban Biosphere Reserve of southern West Bengal, India offers an ideal locale where Hyperspectral Remote Sensing may be applied for mapping diverse range of mangrove plantations that are unique to this pristine ecological system. This delta is characterized by both ‘pure’ and ‘mixed’ mangrove forest patches where photons interact with multiple species within the instantaneous field of view of the hyperspectral sensor, and multiple scattering between the vegetation canopies becomes significantly nonlinear. This paper attempts to apply the principle of multiple scattering of light in naturally occurring conditions and see how best they describe the resultant mixed spectra for certain endmember distributions. It is observed that natural forests, mixed mangrove forest in this case, are better suited for non-linear scattering models as compared to linear models. The non-linear model has successfully identified areas of interaction of mangrove mixtures such as ceriops-excoecaria-phoenix, excoecaria- avicennia alba avicennia officinalis etc. in the study area.

Mangroves are a group of halophytic, evergreen, woody plants and shrubs that occupy the intertidal zone. The Jaffna peninsula has some of the major mangrove sites in Sri Lanka with large extents of undisturbed mangroves. As a result of the three-decade long armed conflict that prevailed in the entire northern part of the Island, mangrove diversity and distribution has never been evaluated since 1969. The objective of the present study was to identify the mangrove species and their distribution in the Jaffna peninsula. Five locations were selected based on the distribution of mangrove vegetation. These are Mandaitivu (East and West), Sirudivu, Kuruchidivu, Kurikadduwan, and Kaluthaipiddi. Random quadrat method was used to assess the abundance of mangrove species in the area. A total of 21 species of true mangrove plants have been recorded in Sri Lanka and the present study identified seven (07) species in the Jaffna peninsula. These are Bruguiera cylindrica, Avicennia marina, Avicennia officinalis, Rhizophora mucronata, Excoecaria agallocha, Lumnitzera racemosa, and Ceriops tagal. A mangrove associate, Acanthus ilicifolius was also recorded. Of these, Bruguiera cylindrica is a species with restricted distribution. In the present study it was recorded only from Sirudivu (density 169/km2). Avicennia marina is the dominant species on the Islands and Southern coastal line. The island of Mandaitivu had a high density of this species (293/km2 on East and 1208/km2 on West Mandaitivu). Kuruchidivu also had a higher density (2571/km2) of this species compared to other island areas. Avicennia officinalis was restricted to Sirudivu and Kuruchidivu (density 246/km2 and 100/km2 respectively). Mangroves are one of the most diverse ecosystems and they provide suitable habitats for a large number of migratory bird species and other aquatic species such as fishes, shrimps, crabs, etc. which are important to marine fisheries in Sri Lanka. They are one of the most productive ecosystems on the earth. The mangroves also protect the coasts from the impacts of storms. The study area has large extents of relatively undisturbed mangroves, found mainly on the Eastern side of the Jaffna peninsula along with the lagoon line and the Southern part of the peninsula along the coastal line. Hence the present area has a considerable conservation value. Keywords: True mangroves, Mangrove associates, Distribution, Islands, Jaffna Peninsula

Anthropogenic activities have always been the cause of most environmental degradation, and mangrove disappearance is no exception. A comparative assessment on the biodiversity of natural and degraded mangrove forests has been undertaken, looking at the biomass, both above-ground and below-ground. The natural and the degraded mangrove forests were situated at Kuala Selangor and Sungai Haji Dorani, respectively, both on the West coast of Peninsular Malaysia. A random sample scheme with quadrate sample plots (10 m × 10 m) was adopted for the measurement of the diameter at breast height and total height of individual tree species at both forests. Diversity indices and above- and below-ground biomass were estimated from this inventory. Eight mangrove tree species were identified at both study areas, namely: Bruguiera parviflora, Avicennia officinalis, Rhizophora mucronata, Sonneratia alba, Avicennia marina, Bruguiera cylindrica, Xylocarpus mekongensis and Excoecaria agallocha. The mangrove species in Sungai Haji Dorani showed high diversity with a Shannon–Weiner Index (H′) value of 0.91, compared to the natural mangrove of Kuala Selangor which has a lower value, H′ = 0.55. The dominant species in the natural mangrove area was B. parviflora, with the highest Important Value Index (IVI) of 70.96 %, as opposed to A. marina which was the most common species in the degraded mangrove area, with IVI of 49.16 %. An estimate of 305.46 t/ha of above-ground biomass was calculated for the natural mangrove, while 122.78 t/ha was obtained for the degraded mangrove forest. This contrasts with the below-ground biomass estimates, which were 14.09 t/ha for the natural mangrove and 36.35 t/ha for the degraded mangrove.

This study was conducted to assess the species diversity and carbon sequestration potential of a natural mangrove stand in Botoc, Pinabacdao, Samar, the Philippines. Using the quadrat sampling technique, 12 plots with a size of 100 m2 were established to facilitate inventory and measurement of trees. Shannon-Wiener index and allometric equations were used to determine species diversity, and biomass and tree carbon storage, respectively. The community's species diversity (H′ = 1.6365) was very low with a total of eight true mangrove species recorded, dominated by Avicennia officinalis with an importance value of 134.80%. Among the plots, a greater percentage of the total biomass was accounted to the above-ground biomass, corresponding to 74% (297.20 t ha−1), while the remaining 26% (103.87 t ha−1) was credited to the root biomass. The total carbon sequestered and stored in the biomass of the natural mangrove stand was 188.50 t C ha−1 equivalent to 691.81 t CO2 ha−1. The biomass and carbon density estimates...

The aim of the present work is to unveil the potential of some of the unexplored remote sensing techniques for mangrove studies. The paper deals with the classification of an Earth Observing–1 Hyperion image of the mangrove area of Bhitarkanika National Park, Odisha, India into mangrove floristic composition classes. Out of 196 calibrated bands of the image, 56 were found to be highly uncorrelated and contained maximum information; therefore, these 56 bands were used for classification. Amongst the three full–pixel classifiers tested in the investigation, Support Vector Machine produced the best results in terms of training pixel accuracy with overall precision of 96.85 %, in comparison to about 70–72.0 % for the other two classifiers. A total of five mangrove classes were obtained – pure or dominant class of Heritiera fomes, mixed class of H. fomes, mixed Excoecaria agallocha with Avicennia officinalis, mixed class of fringing Sonneratia apetala and class comprising of mangrove associates with salt resistant grasses. Post–classification field data also established the same. Pure or dominant classes of H. fomes occupied more than 50 % of the total mangrove vegetation in the forest blocks of the National Park. Spectral profile matching of image pixels with that of in–situ collected canopy reflectance profile revealed good match for H. fomes (pure or dominant stands). Red–edge index, which was a preferred criterion for matching was notably correlated in case of H. fomes and E. agallocha. The outcomes indicated the efficacy of hyperspectral canopy reflectance library for such kind of work. It is hoped that the methodology presented in this paper will prove to be useful and may be followed for producing mangrove floristic maps at finer levels.

article For mangroves with almost no tidal influence and a subsequent mosaic vegetation structure we describe the relation between propagule predators and both vegetation structure and environmental factors on a vegetation assemblage or 'forest patch' level. We then report the interaction between natural propagule predation and human influence. In different forest patches dominated by Avicennia officinalis, Excoecaria agallocha, Lumnitzera racemosa, Rhizophora apiculata or R. mucronata or in open or mixed areas identified from aerial photographs, the predation on propagules of A. officinalis, B. gymnorrhiza, R. apiculata and R. mucronata was monitored in a total of 24 experimental plots (3 per forest patch). Relationships to environmental factors (topography, water level, rainfall and season) on the level of predation were investigated. The highest predation intensity by crabs was on A. officinalis propagules, and in E. agallocha forest patches. Predation by crabs, snails, insects and mammals was observed, and the significant differences in predation intensity across species and across forest patches were explained directly by propagule predator identity and abundance, and by the interaction between rainfall, water level and microtopography. We illustrated how hydrography changes alter the behaviour of propagule predators and play a role in the shaping of vegetation structure by reconstructing the lagoon water level of a site over a period of 50 years based on rainfall data. This time frame covered both a condition without and with human impacts, and past and present propagule predation settings were confronted with the simulated hydrology. The importance of spatial and temporal microhabitat variations in opening multiple successional pathways in vegetation dynamics is illustrated, and is highly relevant for ecosystems with unpredictable or short-lived (b20 years) patchy vegetation structures and microhabitats.

This paper assesses the extent of success and failure of mangrove plantations in Myanmar, restored by local people with the help of foresters under a community forestry program initiated in 1995. The species of these restored plantations are Avicennia officinalis, Avicennia marina and Heritiera fomes, each of which was restored on two plots, one on low and one on high ground, yielding a total of six plots. These plots have been continuously monitored in order to investigate survival and growth rates. The plots were established on abandoned land that had been previously used for paddy cultivation. Cyclone Nargis hit these plantations during the monitoring period, at the beginning of May, 2008. As a consequence, the survival rates of A. officinalis on low ground and A. marina on high ground declined slightly, but the overall affect was not severe. Excluding individuals affected by the cyclone, height and diameter growth of A. officinalis and A. marina were significantly higher on low ground than on high ground, i.e. on sites thought to be consistently similar to the natural habitats of these species. Contrary to these two Avicennia species, the height growth of H. fomes was higher on high ground than on low ground; the diameter growth was not significantly different. As the growth of H. fomes was very slow, however, it is still not possible to describe the differences clearly. This study may provide useful guidelines for foresters and local people to establish successful mangrove restorations and to predict production from community-owned mangrove forests.

Mangroves are highly productive ecosystems occurs intertidal regions only. Mangroves and associated flora occurring in two major estuaries of Godavari river (India) were studied using transect with 4x4 m2 quadrats and the quadrat samples were analyzed. Seasonal data were collected on environmental, hydrographical and chemical observations from three different stations of the two estuaries. Low values in Secchi depth, salinity and pH were reported during the monsoon season, while higher values were reported in pre-monsoon and post monsoon seasons. In the present study three mangrove species and nine associated species were reported. Transect studies in these two estuaries showed that mangrove and halophytes occurred up to 40 meters from water front region. In some places mangrove vegetation was in the form of long strips only. In Vainateyam estuary, the species with the highest density was Suaeda monoica whereas the species with lowest density was Avicennia officinalis. In Vashista estuary, maximum density was reported for Suaeda maritima and minimum density for Avicennia officinalis. The maximum height in these two stations varied from 5 to 8 meters only. Percentage frequencies of DBH (Density at Breast Height) classes were estimated. In the present study only two diameter classes were reported. This is indicative of the small and bushy mangrove vegetation in the region studied. Human interference, urban settlements and aqua industry play a critical impact on the survival of these tropical ecosystems. If management and conservation programmes are not undertaken, these ecosystems may be depleted.

The study was conducted in the Negombo estuarine lagoon locates in the Gampaha District of Sri Lanka. In this research, an investigation was carried out to identify and assess the distribution pattern of mangrove diversity across salinity gradient in the lagoon. A field survey was performed to collect primary data and vegetation sampling was carried out in two transects along the periphery of the lagoon. Located sample size is 5 m × 10 m. Fifteen samples were selected maintaining distribution of species heterogeneity. Only mangrove species were enumerated. In situ field-testing of salinity was carried out at monthly intervals during October 2012 to September 2013 for 15 samples. Shannon-Wiener diversity index was calculated to compare about the diversity of mangrove species. The Inverse Distance Weighted (IDW) interpolation technique in ArcGIS was performed to prepare spatial distribution maps. There are 18 mangrove species identified belonging to 14 genera and 12 families. Among them 14 species are “True” and 4 species are “Mangrove Associates”. Rhizophora mucronata, Rhizophora apiculata, Avicennia officinalis, Excoecaria agallocha and Acrostichum aureum are the most common species and Aegiceras corniculata, Aegiceras corniculata, Bruguiera sexangula and Xylocarpus granatom are the least common true mangrove species types found in the Negombo lagoon. Spatially the highest mangrove species diversity could be identified in the southern quarter and a small patch around the outlet of the lagoon. Relatively low species diversity is identified at the middle periphery of the lagoon. Spatial differences of the floristic composition and the diversity reflect the salinity tolerance ability of the different mangrove species.

The present paper deals with ecological investigation of mangrove ecosystem of Bhitarkanika sanctuary in Odisha. The structural parameters like height, diameter and basal area of mangrove tree species at four sites of the sanctuary viz., Bhitarkanika, Dangmal, Thakurdia and Kakranasi, were measured and compared with the mangroves of other parts of the world. Dominance diversity curve was found lognormal in shape for this area representing high diversity condition. Of the 29 species recorded from the study sites, only 8 species were common at all sites. The trees with higher DBH classes were found in the protected core sites of Bhitarkanika and Dangmal. Avicennia officinalis and Sonneratia apetalaformed the top storey in the river bank regions in Bhitarkanika and Dangmal forest blocks, whereas Sonneratia caeseolaris and Rhizophora mucronataformed top canopy in the river bank areas of Thakurdia and Kakranasi blocks. Exocaria agallocha and Hertiera fomes generally have higher basal area and they formed the top storey in the interior forest areas at all sites. Across all sites and species, it was observed that Exocaria agallocha, Avicennia officinalis and Hertiera fomes accounted for more than 50% of the total Importance Value Index (IVI) in Bhitarkanika sanctuary. The mangroves of Bhitarkanika have lower heights, low basal area and higher number of plants compared to other mangroves of the world. The Riverine species of Bhitarkanika ecosystem have much higher complexity index values than other mangrove ecosystems of the world, which indicates that this ecosystem is favourable to a diversity of mangrove species.

The aim of this study is to clarify the survival and growth performances of six native mangrove species (Avicennia officinalis, Avicennia marina, Bruguiera sexangula, Heritiera fomes, Rhizophora apiculata and Sonneratia apetala) that were replanted on abandoned paddy fields in the Ayeyarwady (AYWD) Delta of Myanmar where natural mangroves once existed. The findings indicate that low survival rate and poor growth of the trees can be attributed to both ground level and biotic disturbances. The growth of trees at low ground was obviously better than that of trees at high ground. At low ground, S. apetala demonstrated the best growth and R. apiculata had the highest survival rate. At high ground, the survival and growth rates of A. officinalis were the best. All the species replanted showed the highest increments of tree height from the middle of rainy season to the beginning of winter.

Angke-Kapuk Protected Forest with total area 44.76 ha is part of the Tegal Alur-Angke Kapuk mangrove forests. Therefore, this forest has important role as an interface between terrestrial and marine ecosystems, whether physical, biological or social-economic aspects, todetermine mangrove ecosystem as a productive and unique ecosystem in the coastal area. However, the study of floristic of the mangrove vegetation in this forest has never to be done previously. According to the study on September to November 2003, in this forest found 8 species of mangrove trees. The tree species can be classified into two groups. The first group is true mangroves (7 species), i.e. Avicennia officinalis, Rhizophora apiculata, R. mucronata, R. stylosa, Sonneratia caseolaris (major component), Excoecaria agallocha, and Xylocarpus moluccensis (minor component). The last group is mangrove associate, i.e. Terminalia catappa. In this forest also found 7 tree species, i.e. Bruguiera gymnorrhiza, Calophyllum inophyllum, Cerbera manghas, Paraserianthes falcataria, Tamarindus indicus, Acacia mangium, and A. auriculiformis as introduced species. The growth level of B. gymnorhiza, C. inophyllum and C. manghas up to now is seedling and sapling, while the growth level of another introduced species is till in pole and tree.© 2005 Jurusan Biologi FMIPA UNS SurakartaKey words: mangrove tree species, Angke-Kapuk Protected Forest.

This study aimed to determine the effect of elevation on survival and growth of mangrove seedlings during the establishment period. Seven typical mangrove species, Rhizophora mucronata Poir, R. apiculata Bl., Bruguiera cylindrica (L.) Bl., Ceriops tagal (Pirr.) C.B. Rob., Sonneratia alba J. Sm., Avicennia officinalis L. and Xylocarpus granatum Koenig were planted at various topographic sites in an intertidal zone of Phang Nga province, southern Thailand. These six bare areas included two that were abandoned after tin mining and four gap areas in natural habitats in June 1998. The experimental plots were on a slope and showed a maximal elevation difference of 1.8 m. The plots were naturally submerged with 2–3% saline water twice a day. Salinity, pH and the concentrations of several ions in the soil water were similar in all the plots. Survival and growth performance of seedlings were measured every 6 months. Many seedlings of B. cylindrica, C. tagal and X. granatum planted at lower elevations died with a year. R. mucronata and S. alba survived even at the lowest elevations, but showed changes in growth rate in response to topography. Thus, early growth of the seven mangrove species at different elevations differed and showed increasing tolerance to higher tidal inundations in the order: R. mucronata, S. alba, R. apiculata, A. officinalis, C. tagal, B. cylindrica and X. granatum. These findings provide guideline information for appropriate species selection in a mangrove rehabilitation program.

For sustainable management of mangrove ecosystems, there is a pressing need to increase our knowledge of fish and invertebrates associated with this system. This study sampled microhabitats (89–258 ...

Attaragoda is a mangrove wetland situated in the Southern Coast (Latitude: 6° 1′ 60N, Longitude: 80° 15′ 0E), 3km outside Galle. This luxuriant patch of mangrove forest faces immense pressure due to human activities. Diversity and distribution of mangrove species in relation to salinity levels and species richness of avifauna were studied from January to June 2009The area was subdivided into three zones based on salinity levels. Zone 1 with recurrent tidal effect had a salinity range of 33-40ppt. Salinity of Zone 2 with moderate influence of tides ranged between 26- 32ppt. Salinity of Zone 3 with least influence of tides ranged between 20-28ppt. Diversity and distribution of mangrove flora was carried out using quadrat (20×20m) sampling technique. Species richness of birds were determined by carrying out line transects and opportunistic observations. Shannon-Weiner Diversity Index (DI) was calculated to describe floral diversity. Twelve species of true mangroves and six mangrove associates were recorded. Out of eighteen species six were known to be introduced to the wetland. Species richness of Zone 1, 2 and 3 were seven (No. of plots sampled; n=7), six (n=3) and five (n=4) respectively. Increased species richness of Zone 1 is due to introduced species of true mangroves: Rhizophora mucronata, Ceriops tagal and Aegiceras corniculatum Highest diversity and evenness were recorded from Zone 3 (DI=0.42, J=0.78) and lowest diversity was recorded in Zone 1 (DI=0.23, J=0.46). Dominant species in Zone 1 were Rhizophora apiculata , Excoecarica agallocha and Clerodendrone inerme . Zone 2 (DI=0.33, J=0.46) was dominated by Rhizophora apiculata and Acanthus illicifolius. True mangrove species Sonneratia caseolaris , Avicennia officinalis, Heritiera littoralis, Luminitzera racemosa and mangrove associate Cerbera manghas were recorded opportunistically in Zone 2. Acanthus illicifolius was exclusive to Zone 2. Avifauna consisted of 35 species, of which, 20 were wetland species. There were nine species of migratory birds including one scarce winter visitor- Malayan Night Heron, indicating that Attaragoda wetland is an important destination for migratory birds. Immediate steps should be taken to assure degradation of this wetland habitat by human interventions.

The growth performance of seedlings of seven species of true mangroves (Avicennia marina, A. officinalis, Bruguiera gymnorrhiza, B. sexangula, Rhizophora apiculata, R. mucronata, and Sonneratia caseolaris) in response to two contrasting salinity regimes, low (i.e. 3-5) and medium (i.e. 25-27), was studied. Species represented all categories relevant to vivipary (i.e. true viviparous species, cryptoviviparous species and non-viviparous species), and included closely related pairs as well as species commonly used in replanting in Sri Lanka. Species could be ranked in descending order of salinity tolerance as A. marina > R. mucronata > R. apiculata > B. gymnorrhiza > A. officinalis > B. sexangula > S. caseolaris, hence taxonomically similar species and those sharing vivipary characteristics may be distant in salinity tolerance. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA., SCOPUS: ar.j, FLWIN, info:eu-repo/semantics/published

The mangroves of Kerala on the south-west coast of India are fast disappearing due to land reclamation and other anthropogenic disturbances. There are very few ecosystem level studies made in these much threatened biotopes in Kerala. The present study involves the measurement of heavy metals in the mangrove flora and sediments of three mangrove habitats along the Kerala coast. Sampling was carried out for a period of one year at bi-monthly intervals, with concentrations of Fe, Mn, Cu, Zn, Pb and Co analysed using atomic absorption spectrophotometry. An appreciable variation was observed in metal concentrations in different mangrove species. Cu, Zn and Pb were found to be in higher concentrations in Avicennia officinalis whereas higher levels of Fe, Mn and Co were observed in the species Barringtonia racemosa. The analysis of heavy metals indicated a high level of metal pollutants such as Fe, Cu, Zn and Pb in the mangrove habitats of Quilon and Veli compared to the relatively uncontaminated areas of Kumarakom.

Purpose. The present study is aimed at investigating the diversity and ecology of mangrove litter inhabiting microarthropods with a view to assess their functional role in the nutrient cycling by way of decomposition of mangrove litters. Design/methodology/approach. Samplings were made at monthly intervals for the estimation of ecological parameters, recording fluctuation of population and community structure from the selected study site of Midnapore coast of West Bengal, India. Experimental laboratory studies were also undertaken for assessing the rate of insitu decomposition of selected mangrove plant, Avicennia officinalis (L) and phase wise occurrence of microarthropods in decomposing litter. Findings. A total of 44 species of microarthropods belonging to seven major taxonomic groups viz. Acarina (36.3%), Collembola (27.2%) Coleoptera (10%), Diptera (5.7%), Isopoda (5.1%), Hymenoptera (5%) and other associated litter inhabiting microarthropod fauna (10.6%), displayed distinct seasonal fluctuation with regard to their population density and community structure in relation to fluctuating major physico-chemical parameters. Maximum decomposition was found on twelve months (70%) and that of minimum (34%) was observed on three months. Maximum diversity and density of fauna were recorded during six months to nine months of decomposition. Originality/value. Litter inhabiting soil microarthropods play significant role in the energy flow and nutrient cycling in mangrove ecosystem by breaking leaves for the consumption thereby promote leaching and subsequently enhance biochemical alteration along with associated microbial population.

The UmIalazi river in Zululand is undergoing large scale changes due to deposition of mud from cultivated areas and a simultaneous rapid colonisation by mangroves chiefly Avicennia officinalis . The result is that open mud banks are being consolidated, shallows are changing into mangrove swamps and eventually into dry land. Much useful information can, be obtained from the study of aerial photographs and in the case of the Zululand coastal rivers we are fortunate in having two series of photographic surveys by the Trigonometrical survey. The photographs of the Umlalazi were made in 1937 and in 1960 and are reproduced in Fig. 1. The spread of mangroves and mud banks is obvious. In view of these changes it was felt that an ecological survey should be undertaken in order to record the present physical conditions and animal life in the estuary. As the mangrove invasion progresses the estuary will become narrower, shallows will disappear and tidal currents will become stronger. This should result in an increase in the fauna associated with mangrove swamps and a decrease in the shallow water fauna. Zoologica Africana 2 (1): 1-24

SUMMARY (1) Three species of plants, Acanthus ilicifolius, Avicennia officinalis and Bruguiera gymnorhiza, grow abundantly in the tidal mangrove area of the Sunderbans, India. (2) The leaves from plants not normally submerged and from those periodically submerged have been analysed for their hydrophobic components (lipid, wax ester and hydrocarbons). The weights of hydrocarbons and wax esters per unit leaf area of the submerged plants were about three times greater than those of emergent plants; this apparently makes them tolerant to flooding. (3) In addition, the area, thickness, fresh weight to dry weight quotient, loss in weight on drying, and chlorophyll content of leaves were all higher in the periodically submerged plants. The great increases in leaf area and chlorophyll content may help in overcoming the limitations imposed on photosynthesis due to periodic submergence.