Mangrove Composition Research Articles

Drivers of coastal shoreline change: case study of hon dat coast, Kien Giang, Vietnam.

Coastal shorelines are naturally dynamic, shifting in response to coastal geomorphological processes. Globally, land use change associated with coastal urban development and growing human population pressures is accelerating coastal shoreline change. In southern Vietnam, coastal erosion currently is posing considerable risks to shoreline land use and coastal inhabitants. The aim of this paper is to quantify historical shoreline changes along the Hon Dat coast between 1995 and 2009, and to document the relationships between coastal mangrove composition, width and density, and rates of shoreline change. The generalized linear mixed-effects models were used to quantify the major biophysical and land-use factors influencing shoreline change rates. Most significant drivers of the rates of change are cutting of mangroves, the dominant mangrove genus, changes in adjacent shoreline land use, changes of shoreline land cover, and width of fringing mangroves. We suggest that a possible and inexpensive strategy for robust mangrove shoreline defense is direct mangrove planting to promote mangrove density with the presence of breakwater structures. In the shorter term, construction of coastal barriers such as fence-structured melaleuca poles in combination with mangrove restoration schemes could help retain coastal sediments and increase the elevation of the accretion zone, thereby helping to stabilize eroding fringe shorelines. It also is recommended that implementation of a system of payments for mangrove ecosystem services and the stronger regulation of mangrove cutting and unsustainable land-use change to strengthen the effectiveness of mangrove conservation programs and coastal land-use management.

Using expert knowledge and modeling to define mangrove composition, functioning, and threats and estimate time frame for recovery.

Mangroves are threatened worldwide, and their loss or degradation could impact functioning of the ecosystem. Our aim was to investigate three aspects of mangroves at a global scale: (1) their constituents (2) their indispensable ecological functions, and (3) the maintenance of their constituents and functions in degraded mangroves. We focused on answering two questions: “What is a mangrove ecosystem” and “How vulnerable are mangrove ecosystems to different impacts”? We invited 106 mangrove experts globally to participate in a survey based on the Delphi technique and provide inputs on the three aspects. The outputs from the Delphi technique for the third aspect, i.e. maintenance of constituents and functions were incorporated in a modeling approach to simulate the time frame for recovery. Presented here for the first time are the consensus definition of the mangrove ecosystem and the list of mangrove plant species. In this study, experts considered even monospecific (tree) stands to be a mangrove ecosystem as long as there was adequate tidal exchange, propagule dispersal, and faunal interactions. We provide a ranking of the important ecological functions, faunal groups, and impacts on mangroves. Degradation due to development was identified as having the largest impact on mangroves globally in terms of spatial scale, intensity, and time needed for restoration. The results indicate that mangroves are ecologically unique even though they may be species poor (from the vegetation perspective). The consensus list of mangrove species and the ranking of the mangrove ecological functions could be a useful tool for restoration and management of mangroves. While there is ample literature on the destruction of mangroves due to aquaculture in the past decade, this study clearly shows that more attention must go to avoiding and mitigating mangrove loss due to coastal development (such as building of roads, ports, or harbors).

A Holocene record of coastal landscape dynamics in the eastern Kimberley region, Australia

A 6-m-long sediment core from the King River region of north-west Australia has been analysed using sedimentological and palynological techniques. The core spans most parts of the Holocene and contains a detailed record of early to mid-Holocene landscape development. In the early Holocene an intertidal environment supported a diverse and probably extensive mangrove forest. Intensified fluvial activity, high mangrove biodiversity and the proximity of freshwater swamp vegetation reflect enhanced summer monsoon rainfall. From 7.4k cal a BP onwards, the mangrove forest starts to contract reaching minimum (and probably present-day) extent by 6.5k cal a BP. Late Holocene aridification led to shifts in mangrove composition, the expansion of hypersaline flats and the transition of freshwater swamps to intermittent wetlands. In addition, fire potentially played an increasing role in controlling ecosystem composition, in particular in the savanna/woodland vegetation. This record is the first of its kind from coastal north-west Australia and demonstrates that sea-level and climatic fluctuations, in addition to local geomorphological settings, are major controllers of landscape development. Although the general pattern of change is similar to other sites in tropical Australia, detailed analysis shows that the timing and character of vegetation shifts are considerably different.

Environmental and anthropogenic influences on the distribution, structure, and floristic composition of mangrove forests of the Gulf of Urabá (Colombian Caribbean)

The Gulf of Urabá is the largest sea inlet along the Colombian Caribbean coast, and is highly influenced by freshwater currents that carry substantial quantities of sediment, shaping the coastal geomorphology, and vegetation species composition and distribution. Despite regional low tides and pore-water salinity levels, we hypothesised high variability in mangrove vegetation along the coasts due to local environmental variation, coupled with a recognised physiographic classification. Mangrove forests were mapped and classified following analysis of aerial photographs. Based on 87 circular 500m2 plots, we assessed the structure, floristic composition, and environmental attributes of mangroves. Three mangrove forest types were identified, according to the physiographic classification based on location; riverine, basin, and fringe; and a mangrove type in a highly disturbed stage. Significant differences among mangroves were found; therefore our hypothesis was accepted. Rhizophora mangle, Laguncularia racemosa, and Avicennia germinans exhibited the highest importance values (IVI) in fringe and riverine mangroves; and in basin mangroves, A. germinans showed the highest IVI, with the importance order of these species inverted. Small highly disturbed mangrove fragments were dominated by R. mangle. Tree diameters and heights were asymmetric unimodally distributed, suggesting large forest disturbances related to timber overexploitation, and poor conservation status. Differences among mangrove types were related to soil salinity, granulometry, and nutrient concentrations. The sediment loads transported by rivers, soil nutrient concentrations, and vegetation structure revealed high fluvial and anthropogenic influences on forests, and these conditions are promoting colonisation by alluvial forest species.

Mangrove composition and structure at the Welu Estuary,Khlung District, Chanthaburi Province, Thailand

Mangrove composition and structure at the Welu Estuary,Khlung District, Chanthaburi Province, Thailand

Micronesian Mangrove Forest Structure and Tree Responses to a Severe Typhoon

Tropical cyclones are common disturbances that have strong effects on mangrove composition and structure. Because there are numerous ecosystem services provided by mangroves, it is important to understand their adaptations and responses to these climatic events. In April 2004, Typhoon Sudal, a category 3–4 cyclone, passed over the state of Yap, Federated States of Micronesia. For four months following the typhoon we measured forest structure, above-ground biomass, tree mortality and response in six mangroves. The sites were dominated by species common in mangroves throughout the Indo-Pacific—Sonneratia alba, Brugueira gymnorrhiza, and Rhizophora apiculata. Total above-ground biomass (TAGB) of mangrove forests ranged from 211–573 Mg ha-1. Tree mortality ranged from 6% to 32% among stands. Adaptations and responses to the typhoon varied by species, as well as by geographic location. Sonneratia alba had a higher frequency of mainstems broken (26%), but was the only species that vigorously sprouted from dormant basal or epicormic tissues. Standing live trees accounted for 80–95% of TAGB, suggesting that adaptations of mangrove trees can facilitate the persistence of an intact forest structure following typhoons of this intensity. Climatic changes such as sea level rise and increased severity of cyclonic events could alter this relationship.

Modern pollen rain in mangroves from San Andres Island, Colombian Caribbean

The precise characterisation of present-day mangrove ecosystems from modern pollen rain facilitates the accurate use of fossil pollen data for late Quaternary sea level and environmental reconstructions. Here, we investigate whether the analysis of pollen rain data corroborates existing floristic and structural characterisation of different mangrove types at the Caribbean island of San Andrés, Colombia. At 82 plots along 20 transects of four distinct mangrove types, samples were obtained of (i) surface sediments for pollen analysis, and (ii) a range of environmental parameters (including inundation levels, salinity and pH). This information was compared to previously sampled mangrove composition and tree basal area. In surface sediment samples 82 pollen taxa were found, from which 19 were present in the vegetation plots. However, because pollen may be transported by wind and/or watercourses, the overall floristic composition of the different forest types may not necessarily be reflected by the pollen spectra. Local vegetation (i.e. mangroves and beach) represented > 90% of the pollen spectra, while the regional one (i.e. hinterland forests) represented < 5% of it. Unlike the four mangrove types that were previously described in the vegetation, the analysis of pollen samples suggested only three distinct types of forest. The groups were characterised based on (i) the dominance of at least one of the true mangrove species from pollen data ordination and the presence of associated species, and (ii) their relationship with environmental parameters. Rhizophora was present in all plot samples, but did not contribute to forest type separation. In fact, just three true mangrove species proved reliable indicators of (i) high salinity and fringe mangroves (i.e. Avicennia), (ii) high pH levels and landward mangroves (i.e. Conocarpus), and (iii) natural or anthropogenic caused disturbance of forest stands ( Laguncularia and associated Acrostichum fern). Hence our study confirms that mangrove pollen spectra can be accurately used to describe different mangrove environments for fossil based palaeoecological reconstructions.

Alteration of the chemical composition of mangrove ( Laguncularia racemosa) leaf litter fall by freeze damage

Resorption, the remobilization and subsequent transport of leaf constituents (e.g. N, C, and P) into the perennial structures of the plant prior to leaf abscission, may be interrupted or prevented by stressors that interfere with the normal course of leaf senescence. Mangroves that lie along the latitudinal extremes of their distribution are susceptible to freeze damage that may periodically disrupt the normal resorptive process. On January 24, 2003, the white mangroves ( Laguncularia racemosa) in a northern portion of Tampa Bay, Florida were exposed to freezing temperatures for 8 h. The leaves of these trees were noticeably withered by this freeze event. Over a four-month period following the freeze, we compared the subsequent rate of leaf litter production at this site to that of two, apparently undamaged, fringing mangrove forests in Tampa Bay. We also examined the carbon and nitrogen concentrations of the leaf litter from the litter traps at these three sites and compared it to that of green, yellow (nearly senescent), and freeze-damaged leaves hand-picked from the mangroves. A pronounced pulse of leaf litter fall (maximum: 7 g dw m −2 d −1) was found at the putatively freeze-damaged site but not at the two comparison sites. In addition, the leaf litter at the freeze-damaged site was richer in nitrogen and carbon, and had a lower C:N than litter collected at the comparison sites. Comparison of the elemental composition of this leaf litter with leaves hand-picked from the mangroves suggests that the freeze event killed the leaves of L. racemosa, interrupting the process of resorption. This perturbation to nutrient flow may have implications for mangrove forest structure and the entry of mangrove material into food webs.

Interactive effects of salinity and irradiance on photoprotection in acclimated seedlings of two sympatric mangroves

The synergistic effects of irradiance and salinity on leaf angle, the photochemical efficiency of photosystem II and photosynthetic pigment composition of mangroves were studied in a factorial experiment. Seedlings of Aegiceras corniculatum (L.) Blanco (Myrsinaceae) and Avicennia marina (Forstk.) Vierh var. australasica (Walp.) Moldenke (Avicenniaceae) were grown under salinity treatments (0, 5, 25, 50, 75, and 100% artificial seawater), in full sunlight or under shade cloth (transmitting 30 or 70% sunlight), during summer and autumn. Significant species’ differences and effects of salinity and growth irradiance were found for key measures. Depressions in Fv/Fm due to salinity and growth irradiance were chronic, they were least in 25% seawater and in 30% sunlight, and greater in low and high salinity, and higher irradiance. A diurnal depression of Fv/Fm was superimposed on the chronic depression, and was greater for Ae. corniculatum than Av. marina. Increases in leaf angle; and increases in the size, and de-epoxidation state of the xanthophyll cycle pigment pool afforded protection from adverse effects of excess excitation energy. Adverse effects of the highest salinities on β,β-carotene and β,ɛ-carotene biosynthetic pathways were suggested, particularly in Ae. corniculatum. The ecological significance of differences in species’ extent and temporal patterns of response are discussed.

Transitions in Ancient Inland Freshwater Resource Management in Sri Lanka Affect Biota and Human Populations in and around Coastal Lagoons

The increasing anthropogenic pressure on natural environments results in impacts that affect tropical forest areas and their biodiversity. Adverse impacts on terrestrial and oceanic environments often compound in the intertidal area, where mangrove forest ecosystems thrive. In tropical coastal areas of many developing countries where people depend on wood and other mangrove forest products and services, forest degradation leads to socioeconomic problems. At the same time, increasing freshwater needs in these areas are expected to cause additional problems. On the basis of remote sensing and ground truthing complemented by colonial archival material from the Dutch East India Company (1602-1800), we report that changes to the historic system of inland freshwater management have increased dramatically in recent times. Hydrological changes, such as interbasin transfers, have resulted in a qualitative ecological and socioeconomic degradation in three coastal lagoons in southern Sri Lanka. Variations in river hydrology have caused changes in the areas suitable as mangrove habitat and, thus, have resulted in an altered distribution. However, increases in mangrove area can mask the degradation of the site in terms of floristic composition, significance of the species, and biodiversity (this effect is termed "cryptic ecological degradation"). It is important that such changes be carefully monitored to ensure biological and socioeconomic sustainability.

The effect of selective microbial degradation on the composition of mangrove derived pentacyclic triterpenols in surface sediments

The effect of sedimentary microbial communities on the composition of pentacyclic triterpenol markers as well as β-sitosterol was studied in mangrove surface sediments from North Brazil during a three months degradation experiment. Leaves of Rhizophora mangle, Avicennia germinans and Laguncularia racemosa were incubated with surface sediment and analysed using GC/MS for β-sitosterol, taraxerol, β-amyrin, germanicol, lupeol and betulin. Taraxerol showed the strongest resistance to microbial degradation and clearly increased up to 68% of the sum of the selected markers. Betulin was degraded completely after 40 days, most likely due to its higher polarity. By means of a numerical model the marker composition in surface sediments was explainable as a combination of the dominant input from R. mangle leaves and selective microbial degradation. Calculated marker degradation constants from the model were compared with measured constants in the experiment. On the basis of calculated constants the average age of the organic matter in the upper 1.5 m of sediment was approximately 530 yr.

Lipid composition of mangrove and its relevance to salt tolerance

Lipid compositions of mangrove trees were studied in relation to the salt-tolerance mechanism. Leaves and roots were obtained from seven mature mangrove trees on Iriomote Island, Okinawa: Bruguiera gymnorrhiza, Rhizophora stylosa, Kandelia candel, Lumnitzera racemosa, Avicennia marina, Pemphis acidula and Sonneratia alba. Lipids of mangrove leaves mainly consisted of 11 lipid classes: polar lipids, unknown (UK) 1-6, sterols, triacyl glycerols, wax ester and sterol ester (UK 3 and 4 were found to be tri-terpenoid alcohol in this study). Of these lipid classes, sterol ester was the main lipid in all species comprising 17.6-33.7% of total lipids. Analysis of the chemical structure found that the sterol esters mainly consisted of fatty acid esters of tri-terpenoid alcohols. One major tri-terpenoid alcohol was identified to be lupeol by interpretation of infrared resonance, nuclear magnetic resonance and mass spectrometry. Because of the unique anatomy of the mangrove root, lipid analyses were made separately for epidermis, cortex and innermost stele, respectively. The concentration of free tri-terpenoid alcohols showed a higher tendency in the outside part than in the inside portion of the roots, suggesting their protective roles. Relevance of lipid composition to salt tolerance was studied with propagules of K. candel and B. gymnorrhiza planted with varied salt concentrations. The proportions of free tri-terpenoids increased with salinity in both leaves and roots of K. candel, and only in roots of B. gymnorrhiza. No salt-dependent changes were noted in the phospholipid and fatty acid compositions in both species. These findings suggested that salt stress specifically modulated the terpenoid concentrations in mangroves.

Pyrolysis of recent marine sediments. III. changes in mangrove composition from leaf to sediment

The organic carbon content and composition in terms of extractable, thermally crackable and residual fractions were investigated by temperature controlled pyrolysis for mangrove sediments and plant parts. Mangrove foliage, wood and bark were rich in extractable and thermally crackable organic compounds while in the sediments the residual fraction accounted for >90% of the organic carbon. This transition occurs either during leaf senescence or in the uppermost sediment layers as only minor compositional changes were observed deeper in the sediment.

Sulfur Isotopic Composition of Mangroves

Sulfur isotope ratios of mangrove leaves of 19 species were compared to discuss the species-specific characteristics of sulfur uptake and assimilation. The members of Rhizophora and Bruguiera always show remarkable enrichments of the light isotope, giving negative δ34S values in most cases. The elaborated root systems of such species seem to be closely related to their sulfur absorbing systems as an adaptation to their anaerobic soil conditions.

Early diagenesis of mangrove leaves in a tropical estuary: Bulk chemical characterization using solid-state 13C NMR and elemental analyses

Changes in the chemical composition of mangrove ( Rhizophora mangle) leaves during decomposition in tropical estuarine waters were characterized using solid-state 13C nuclear magnetic resonance (NMR) and elemental (CHNO) analysis. Carbohydrates were the most abundant components of the leaves accounting for about 50 wt% of senescent tissues. Tannins were estimated to account for about 20 wt% of leaf tissues, and lipid components, cutin, and possibly other aliphatic biopolymers in leaf cuticles accounted for about 15 wt%. Carbohydrates were generally less resistant to decomposition than the other constituents and decreased in relative concentration during decomposition. Tannins were of intermediate resistance to decomposition and remained in fairly constant proportion during decomposition. Paraffinic components were very resistant to decomposition and increased in relative concentration as decomposition progressed. Lignin was a minor component of all leaf tissues. Standard methods for the colorimetric determination of tannins (Folin-Dennis reagent) and the gravimetric determination of lignin (Klason lignin) were highly inaccurate when applied to mangrove leaves. The N content of the leaves was particularly dynamic with values ranging from 1.27 wt% in green leaves to 0.65 wt% in senescent yellow leaves attached to trees. During decomposition in the water the N content initially decreased to 0.51 wt% due to leaching, but values steadily increased thereafter to 1.07 wt% in the most degraded leaf samples. The absolute mass of N in the leaves increased during decomposition indicating that N immobilization was occurring as decomposition progressed.

Interpreting ancient swamp communities: Can we see the forest in the peat?

A comparison of the taxonomic composition of mangrove (salt-water) peats from the Everglades National Park and the swamp forests in which the peats accumulated shows that the rank abundance of roots belonging to a taxon in peat can be used to predict the rank abundance of that taxon in the swamp forest. Thus the rank abundance of taxa in permineralized peats can be used to reconstruct ancient swamp-forests. Factors that correlate with salinity, primarily the abundance of detritovores in mangrove swamps, appear to control the shoot-root ratios of the peats studied. Fresh-water swamps peats have few detritovores, low rates of decomposition, and relatively high shoot-root ratios (mean = 2.03).Mangrove peats have many detritovores, high rates of decomposition, and low shoot-root ratios (mean = 0.16). Variation in the shoot-root ratios of marsh peats do not correlate with salinity. However, shoot-root ratios may be useful in predicting the growth environment of ancient permineralized peats derived from ancient swamp forests. Paleotropical permineralized peats of Late Carboniferous age have extremely high shoot-root ratios. A model for peat accumulation based on the work of Janzen (1974) suggests that these high shoot-root ratios may be indicative of tropical blackwater swamps. Factors that are uncorrelated with salinity such as rainfall regime may determine the difference between Okefenokee shoot-root ratios (mean = 2.03) and extremely high shoot-root ratios (> 100) of paleotropical permineralized peats from putative blackwater swamps.

MANGROVE IN THE COASTAL ZONE OF LAMPUNG BAY PROVINCE OF LAMPUNG: A PRELIMINARY STUDY

Study on mangrove forest in the coastal zone of Lampung Bay, Province of Lampung was carried out on March 12 — 30, 2007. The data was collected from 8 stations, (Pidada Bay, Limbungan, Puhawang Kecil Island, Kalangan, Klagian Island, Kapuran, Ringgung, and Hurun Bay) based on the transect method. The result showed that the mangrove in the coastal zone of Lampung Bay was dominated by Rhizophora apiculata. The floristic composition of mangrove in this area consisted of 31 species. Recently, the extent of mangrove in the coastal zone of Lampung Bay was decreasing due to conversion of mangrove into human settlement, fishpond, road, and uncontrolled mangrove exploitation. This situation leads to the depletion of the living organisms which inhabit this area.