Dead Mangrove Research Articles

New Record of Marine Wood-Borer Species in Mangrove Forest of Nusa Lembongan, Bali, Indonesia

Research has been carried out on the presence of wood-borer species in the mangrove forest of Nusa Lembongan, in May-June 2022. The study was conducted at five representative sites of mangrove forests in Nusa Lembongan. The data collection of the mangrove wood-borer was carried out by purposive sampling, which directly searches for dead mangrove stems, twigs, or roots that were attacked by the marine wood-borer found at each site. A total of There were new record four species of mangrove wood-borer, namely, Phaenops sp. beetle group (Coleoptera) and Cenoloba sp. moth group (Lepidoptera), two species of Mollusks, namely, Bankia minima and Bactronophorus sp. were identified. The larval stages of Phaenops sp. were found within the dead mangrove stems of Rhizophora apiculata and Sonneratia alba. Cenoloba sp. which was found in the larvae phase, the host plant was the dead stems of the mangrove Sonneratia alba. Bankia minima, the host plants are dead stems of mangroves Sonneratia alba, Rhizophora apiculata, Rhizophora stylosa and Avicennia sp. Bactronophorus sp., the host plant is dead wood from the mangrove Sonneratia alba, Rhizophora apiculata. The most widely distributed wood-borer species in the mangroves of Nusa Lembongan is Bankia minima. The results showed that four species of marine wood-borer are new records in the mangrove forest of Nusa Lembongan.

Identifikasi Spesies Mangrove dengan Menggunakan Sistem Pesawat Udara Kecil Tanpa Awak di Kawasan Ekosistem Mangrove Sedari, Kabupaten Karawang, Jawa Barat

Remote sensing is one of the effective methods of monitoring mangrove ecosystems. One of the challenges in implementing this method is image resolution. Access to large-resolution imagery as a basic material for spatial analysis is not cheap. Unmanned small aircraft systems (SPUKTA) or drones are able to answer these challenges. Orthophotos obtained from the acquisition of drones are capable of producing large-resolution imagery. This method is then implemented in conservation areas, to facilitate the process of identifying mangrove species in the area. The drone was flown at an altitude of 150 m with a pavement value of 85% for 4 flying missions. The result of processing 1614 aerial photos into orthophotos produced images with a GSD resolution of 4.75 cm/pix. These images are then analyzed with on-screen digitization techniques and visual interpretation. From the total area of the study area of 46.48 ha obtained the digitization results of Rhizophora sp. with a total area of 24.68 ha, Avicennia sp. 7.64 ha, dead mangroves 0.19 ha, and non-vegetation 13.97 ha.

Effect of degradation of a black mangrove forest on seasonal greenhouse gas emissions.

Mangroves play an essential role in the global carbon cycle. However, they are highly vulnerable to degradation with little-known effects on greenhouse gas (GHG) emissions. This study compared seasonal soil carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) fluxes from a black mangrove (Avicennia germinans) forest in the Tampamachoco coastal lagoon, Veracruz, Mexico, in areas subjected to different degrees of environmental degradation (full canopy, transitional and dead mangrove), caused by hydrological perturbation. Furthermore, we aimed at determining the environmental factors driving seasonal fluxes. There was a combined effect of seasonality and degradation on CH4 fluxes, highest during the rainy season in the dead mangrove (0.93 ± 0.18 mg CH4 m-2 h-1). CO2 fluxes were highest during the dry season (220 ± 23 mg CO2 m-2 h-1), with no significant differences among degradation levels. N2O fluxes did not vary among seasons or degradation levels (- 3.8 to 2.9 mg N2O m-2 h-1). The overall CO2-eq emission rate was 15.3 ± 2.7 Mg CO2-eq ha-1 year-1, with CO2 as the main gas contributing to total emissions. The main factors controlling CH4 fluxes were seasonal porewater salinity and the availability of NO2-, NO3-, and SO4-2 in the soil, favored by high water level and temperature in the absence of pneumatophores. The main determining factors controlling CO2 fluxes were water level, porewater redox potential, and soil Cl- and SO4-2 concentration. Finally, N2O fluxes were related to NO2-, NO3-, and SO4-2 soil concentrations. This study contributes to improving the knowledge of soil GHG fluxes dynamics in mangroves and the effect of degradation of these ecosystems on the coastal biogeochemical cycles, which may bring important insights for assessing accurate ways to mitigate climate change protecting and restoring these ecosystems.

SCAT Delineation of Oiling, Cleanup Verification, Chemical Sampling, Coring, and Mangrove Test Planting, Bodo, Eastern Niger Delta, Nigeria

Abstract The Shoreline Cleanup Assessment Technique (SCAT) was effectively applied from 2015 to 2019 during the first stage (Phase 1) of assessment and cleanup of 1000 ha (2471 acres) of intertidal dead mangroves and oiled shorelines in Bodo, Eastern Niger Delta. New SCAT methods and Phase 1 cleanup criteria were developed to delineate oil levels very soft intertidal mud and to monitor clean up efforts. The end goal of Phase 1 was to reduce subsurface oiling less than 35% as visually observed on the water infilling a pit 25–40 cm deep. Oiling levels and cleanup status were documented at 1065 locations with heaviest oil concentrations found in soft muds lining the intertidal channels (2 m tide range). A large-scale chemical sampling program provided contemporaneous pit observations and measured hydrocarbons at 0–5 cm and 15–25 cm depths at 322 sites. There was poor conformance between hydrocarbon analyses and SCAT observations for surface sediments, but better conformance with subsurface chemistry as black and / or brown oil was clearly visible in the pits. Results of SCAT observations and chemical sampling show very high variations throughout the spill affected area and over short distances (5–10 m). A coring study at 30 sites to 2–3 m depths with chemical sampling indicated that oiling is primarily restricted to the upper 40 cm due to water saturated compact deeper sediments inhibiting oil penetration with depth. Lastly, SCAT developed and monitored a mangrove planting program. In spite of high oil levels (TPH over 40,000 at 6 of 7 sites), results from the first year show plant survival at 82% with 46% height growth of the surviving plants. The SCAT Phase 1 findings enabled the definition of the wider scope for remediation and revegetation of the former mangrove areas and will run through the life-cycle of the clean-up project. However, re-pollution remains a challenge to be managed to achieve success.

Optimization of inulinase production by a newly isolated Penicillium amphipolaria strain using solid-state fermentation of hardy sugarcane stems

Abstract A new producer of fungal inulinase Penicillium amphipolaria KAS 2555, has been isolated from the soil area of dead mangroves litter in Herikudru island, followed by the production and optimization of inulinase enzyme by solid-state fermentation (SSF) utilizing a cheap substrate – hardy sugarcane (Saccharum arundinaceum) stems. During the screening process, only P.amphipolaria KAS 2555 displayed a zone of hydrolysis on the inulin media. Thin-layer chromatography (TLC) confirmed the action pattern and the exoinulolytic nature of the inulinase enzyme. After 4 days of fermentation, 2.45 U/gds activity was obtained. The inulolytic nature of the inulinase was proven by obtaining 0.59 I/S ratio. The optimization of media was carried out to obtain a regression model using central composite design. Five media constituents viz., inulin, (NH4)2SO4, K2HPO4, KH2PO4, and, NaCl were used for optimization. The coefficient of determination (R2) calculated was 0.9490 for the inulinase activity. An inulinase activity of 7.59 U/gds (3.1 times higher than non-optimized medium) was observed at optimal conditions: (g/gds) inulin- 0.1, (NH4)2SO4- 0.002, K2HPO4- 0.1, KH2PO4- 0.02 and NaCl- 0.02.

Reconstructing extreme climatic and geochemical conditions during the largest natural mangrove dieback on record

Abstract. A massive mangrove dieback event occurred in 2015–2016 along ∼1000 km of pristine coastline in the Gulf of Carpentaria, Australia. Here, we use sediment and wood chronologies to gain insights into geochemical and climatic changes related to this dieback. The unique combination of low rainfall and low sea level observed during the dieback event had been unprecedented in the preceding 3 decades. A combination of iron (Fe) chronologies in wood and sediment, wood density and estimates of mangrove water use efficiency all imply lower water availability within the dead mangrove forest. Wood and sediment chronologies suggest a rapid, large mobilization of sedimentary Fe, which is consistent with redox transitions promoted by changes in soil moisture content. Elemental analysis of wood cross sections revealed a 30- to 90-fold increase in Fe concentrations in dead mangroves just prior to their mortality. Mangrove wood uptake of Fe during the dieback is consistent with large apparent losses of Fe from sediments, which potentially caused an outwelling of Fe to the ocean. Although Fe toxicity may also have played a role in the dieback, this possibility requires further study. We suggest that differences in wood and sedimentary Fe between living and dead forest areas reflect sediment redox transitions that are, in turn, associated with regional variability in groundwater flows. Overall, our observations provide multiple lines of evidence that the forest dieback was driven by low water availability coinciding with a strong El Niño–Southern Oscillation (ENSO) event and was associated with climate change.

ISOLATION, IDENTIFICATION AND SENSITIVITY OF AMILOLITIC BACTERIA FROM MANGROVE ECOSYSTEM SEDIMENT IN PURNAMA MARINE STATION DUMAI ON THE PATHOGENIC BACTERIA

Litter from the weathering of dead mangrove stems and leaves contains a lot of starch which has potential to be degraded by amylolytic bacteria into simple compounds with the help of the amylase enzyme. Amylolytic bacteria are bacteria that hydrolyze starch into simpler compounds namely glucose with the help of the amylase enzyme. This study aims to 1) isolate, identify and test sensitivity of amylolytic bacterial isolates found at the Purnama Dumai Marine Station, 2) the ability of amylolytic bacterial isolates to inhibit the growth of pathogenic bacteria (Escherichia coli, Pseudomonas aeruginosa and Vibrio alginolyticus) and 3) to determine the of amylolytic bacterial species by 16S rRNA sequence analysis. The results showed 10 bacterial isolates (TR 2, TR 6, TR 7, TR 9, TR 11, TR 13, TR 15, TR 16, TR 18 and TR 20) were able to inhibit the growth of pathogenic bacteria (E.coli, P.aeruginosa and V.alginolyticus). The sensitivity test of isolate TR 20 against E.coli was categorized into weak with inhibition zone diameter of 4.65 mm. Sensitivity of isolate TR 6 against P.aeruginosa was categorized into medium with inhibition zone diameter of 5.22 mm. Then sensitivity of isolate TR 11 against V.algynolyticus was categorized into medium with inhibition zone diameter of 5.55 mm. DNA analysis using 16S rRNA method and BLAST analysis showed similarity of each isolate. Isolate TR 6 was similar to Bacillus paramycoides strain MCCC 1A04098, isolate TR 11 was in a group of Enterobacter cloacae strain ATCC 13047 and TR 20 was in a group of Vibrio harveyi strains of NBRC 15634.

High heterogeneity in soil composition and quality in different mangrove forests of Venezuela.

Mangrove forests play an important role in biogeochemical cycles of metals, nutrients, and C in coastal ecosystems. However, these functions could be strongly affected by the mangrove soil degradation. In this study, we performed an intensive sampling characterizing mangrove soils under different types of environment (lagoon/gulf) and vegetation (Rhizophora/Avicennia/dead mangrove) in the Venezuelan coast. To better understand the spatial heterogeneity of the composition and characteristics of the soils, a wide range of the soil attributes were analyzed. In general, the soils were anoxic (Eh<200mV), with a neutral pH and low concentration in toxic metals; nevertheless, they varied widely in the soil and its quality-defining parameters (e.g., clay contents, total organic carbon, Fe, Al, toxic trace metals). It is noteworthy that the mangroves presented a low FePyrite content due to a limitation in the Fe oxyhydroxide contents, especially in soils with higher organic C content (TOC>15%). Finally, the dead mangrove showed significantly lower amounts of TOC and fibers (in comparison to the well-preserved mangrove forest), which indicates that the C pools in mangrove soils are highly sensitive also to natural impact, such as ENSO.

Assessing relationships between Radarsat-2 C-band and structural parameters of a degraded mangrove forest

Relationships were assessed between mangrove structural data (leaf area index (LAI), stem density, basal area, diameter at breast height (DBH)) collected from 61 stands located in a black mangrove (Avicennia germinans)-dominated forest and both single polarized ultra-fine (3 m) and multipolarized fine beam (8 m) Radarsat-2 C-band synthetic aperture radar (SAR) data. The stands examined included representatives from the four types of mangroves that typify this degraded system, specifically: predominantly dead mangrove, poor-condition mangrove, healthy dwarf mangrove, and tall healthy mangrove. The results indicate that the selection of the spatial resolution (3 m vs. 8 m) of the incidence angle (27–39°) and the polarimetric mode greatly influence the relationship between the SAR and mangrove structural data. Moreover, the extent of degradation, i.e. whether dead stands are considered, also determines the strength of the relationships between the various SAR and mangrove parameters. When dead stands are included, the strongest overall relationships between the ultra-fine backscatter (incidence angle of ∼32°) and the various structural parameters were found using the horizontal-horizontal (HH) polarization/horizontal-vertical (HV) polarization ratio. However, if the dead stands are not included, then significant relationships with the ultra-fine data were only calculated with the HH data. Similar results were observed using the corresponding incidence angle (∼33°) of the fine beam data. When a shallower incidence angle was considered (∼39°), fewer and weaker relationships were calculated. Moreover, no significant relationships were observed if the dead stands were excluded from the sample at this incidence angle. The highest correlation coefficients using the steepest incidence (∼27°) were found with the co-polarized (HH, vertical-vertical (VV) polarization) modes. Several polarimetric parameters (entropy, pedestal height, surface roughness, alpha angle) based on the decomposition of the scattering matrix of the fine beam mode at this incidence angle were also found to be significantly correlated to mangrove structural data. The highest correlation (R = 0.71) was recorded for entropy and LAI. When the dead stands were excluded, volume scattering was found to be the most significant polarimetric parameter. Finally, multiple regression models, based on texture measures derived from both the grey level co-occurrence matrix (GLCM) and the sum and difference histogram (SADH) of the ultra-fine data, were developed to estimate mangrove parameters. The results indicate that only models derived from the HH data are significant and that several of these were strong predictors of all but stem density.

Applications of ALOS PALSAR for monitoring biophysical parameters of a degraded black mangrove (Avicennia germinans) forest

Within the last few decades mangrove forests worldwide have been experiencing high annual rates of loss and many of those that remain have undergone considerable degradation. To understand the condition of these forests, various optical remote sensing platforms have been used to map and monitor these wetlands, including the use of these data for biophysical parameter mapping. For many mangrove forests a reliable source of optical imagery is not possible given their location in quasi-permanent cloud cover or smoke covered regions. In such cases it is recommended that Synthetic Aperture Radar (SAR) be considered. The purpose of this investigation was to examine the relationships between various ALOS-PALSAR modes, acquired from eight images, and mangrove biophysical parameter data collected from a black mangrove (Avicennia germinans) dominated forest that has experienced considerable degradation. In total, structural data were collected from 61 plots representing the four common stand types found in this degraded forest of the Mexican Pacific: tall healthy mangrove (n=17), dwarf healthy mangrove (n=15), poor condition mangrove (n=13), and predominantly dead mangrove (n=16).Based on backscatter coefficients, significant negative correlation coefficients were observed between filtered single polarization ALOS PALSAR (6.25m) HH backscatter and Leaf Area Index (LAI). When the dead stands were excluded (n=45) the strength of these relationships increased. Moreover, significant negative correlation coefficients were observed with stand height, Basal Area (BA) and to a lesser degree with stem density and mean DBH. With the coarser spatial resolution dual-polarization and quad polarization data (12.5m) only a few, and weaker, correlation coefficients were calculated between the mangrove parameters and the filtered HH backscatter. However, significant negative values were once again calculated for the HH when the 16 dead mangrove stands were removed from the sample. Conversely, strong positive significant correlation coefficients were calculated between the cross-polarization HV backscatter and LAI when the dead mangrove stands were considered. Although fewer in comparison to the HH correlations, a number of VV backscatter based relationships with mangrove parameters were observed from the quad polarization mode and, to a lesser extent, with the one single VV polarization data.In addition to backscatter coefficients, stepwise multiple regression models of the mangrove biophysical parameter data were developed based on texture parameters derived from the grey level co-occurrence matrix (GLCM) of the ALOS data. A similar pattern to the backscatter relationships was observed for models based on the single polarization unfiltered data, with fairly strong coefficients of determination calculated for LAI and stem height when the dead stands were excluded. In contrast, similar coefficients of determination with biophysical parameters were observed for the dual and quad polarization multiple regression models when the dead stands were both included and excluded from the analyses. An estimated mangrove LAI map of the study area, derived from a multiple regression model of the quad polarization texture parameters, showed comparable spatial patterns of degradation to a map derived from higher spatial resolution optical satellite data.

A field based statistical approach for validating a remotely sensed mangrove forest classification scheme

Amongst the most threatened ecosystems on Earth, mangrove forests are also one of the more difficult to work in due to their growth in mud and open water coastal zones and their dense tangled stems, branches and prop roots. Consequently, there has been an impetus to employ remotely sensed imagery as a means for rapid inventory of these coastal wetlands. To date, the majority of mangrove maps derived from satellite imagery utilize a simple mangrove classification scheme which does not distinguish mangrove species and may not be useful for conservation and management purposes. Although more elaborate satellite based mangrove classification schemes are being developed, given their enhanced complexity they deserve additional justification for end users. The purpose of this study was to statistically examine the appropriateness of one such classification scheme based on an inventory of field data. In January of 2007 and May of 2008, 61 field sample plots were selected in a stratified random fashion based on a previous classification of a degraded mangrove forest of the Isla La Palma (Sinaloa, Mexico) using Landsat TM5 data. Unlike other previous Landsat TM based classifications of this region, which simply identified the mangrove forests as one class, the mangroves were classified (i.e. mapped) according to four conditions; healthy tall, healthy dwarf, poor condition, and dead mangroves. Within each sample plot, all mangroves of diameter of breast height (dbh) greater than 2.5 cm were identified and their height, condition and dbh recorded. An estimated Leaf Area Index (LAI) value also was obtained for each sample and the shortest distance from the center of each sample plot to open flowing water was determined using a geographic information system (GIS) overlay procedure. These data were then used to calculate mean values for the four classes as well as to determine stem densities, basal areas, and the Shannon–Wiener diversity index. In order to assess the appropriateness of this mangrove classification scheme a discriminant analysis approach was then applied to these field data. The results indicate this forest has undergone severe degradation, with decreasing mean tree heights, mean dbh and species diversity. In regards to the discriminant analysis procedure, further classification of these field plots and cross-validation based on these significant variables provided high classification accuracy thus validating the appropriateness of the satellite based image classification scheme. Moreover, the discriminant analysis indicated that the estimated LAI, mean height, and mean dbh are significant in the separation of the classification of mangrove forest condition along these field sample plots.

Mapping the condition of mangroves of the Mexican Pacific using C-band ENVISAT ASAR and Landsat optical data

To determine whether spaceborne C-band SAR data could be used alone, or in conjunction with optical data, for accurately mapping mangrove forests of the Mexican Pacific, four scenes of dual-polarized ENVISAT ASAR data, at two incidence angles, were collected for the Teacapán-Agua Brava-Las Haciendas estuarine-mangrove complex. Several combinations of these ASAR data were classified to determine the most optimal arrangement for mangrove mapping. In addition, corresponding Landsat TM data were classified using the same training sites. The overall accuracy in mapping these mangroves did improve when more than one polarization mode was employed. In general, the higher incidence angle data (~41º vs ~23º) provided better results. In all circumstances, the optical data alone provided higher classification accuracies. When contained as one mangrove class, the highest overall accuracy achieved using the ASAR data was 54% as compared to 76% for the optical data. When considering four separate mangrove classes, representing the four conditions typical of this system (dead, poor condition, healthy, tall healthy), overall accuracies dropped to 45% and 63%, respectively. With the limited penetration of C-band into canopies, it was difficult to separate healthy and tall healthy mangrove from palm and other terrestrial forests using the ASAR data. In addition to confusion amongst the four mangrove classes, the dead mangrove stands created considerable misclassification as they were readily misidentified with water and saltpan areas in the optical data and with agricultural lands in the ASAR data procedure. Given the advantage of ASAR for identifying dead stands from open water and saltpan, these data were then used in conjunction with the optical data to reduce the misclassification of these areas.

The Use of Multipolarized Spaceborne SAR Backscatter for Monitoring the Health of a Degraded Mangrove Forest

To determine whether multipolarized spaceborne synthetic aperture radar could be used to monitor the health of a mangrove forest, leaf area index, as well as other biophysical parameter data, from stands dominated by white mangrove (Laguncularia racemosa) and located within a degraded mangrove forest were examined in relation to backscatter coefficients from ENVISAT synthetic aperture radar scenes. The results indicate that polarization and, to a lesser extent, incident angle play a significant role in the ability to estimate both leaf area index and mean tree height. No significant linear coefficients of determination were observed between the recorded parameters and the backscatter coefficient from any of the copolarized scenes. With regards to leaf area index, r2 values of 0.82 and 0.73 were calculated for the cross-polarized data at two incident angles. For mean tree height, the linear coefficient of determination was much higher for the smaller incident angle data than for the larger incident angle data. No significant relationships were identified for stem density, basal area, or mean diameter at breast height. It is postulated that the inability of the copolarized ENVISAT advanced synthetic aperture radar data to differentiate between dead mangrove stands and healthy ones is the result of equally high backscatter resulting from strong scattering from trunk–ground double bounce and crown volume, respectively.

Mapping mangrove leaf area index at the species level using IKONOS and LAI-2000 sensors for the Agua Brava Lagoon, Mexican Pacific

Using both IKONOS and in situ LAI-2000 sensor data, a map of estimated LAI, based on NDVI, was created for the Agua Brava Lagoon, Mexican Pacific. The LAI values were then aggregated according to four classes; red mangrove ( Rhizophora mangle), healthy white mangrove ( Laguncularia racemosa), poor condition white mangrove and dead mangrove. Of the live mangrove, calculated at approximately 85% of the forest, mean LAI values of 2.49, 1.74 and 0.85 were determined for the red, healthy white and poor condition white mangrove, respectively. Excluding the dead areas, an overall estimated mangrove LAI value of 1.81 was ascertained for the 71 km 2 of mapped mangrove forest. Although the results do suggest the technique as a very rapid and effective method for monitoring the condition of mangroves at the species level, potential limitations are also discussed.

Assessing the Extent of Saltwater Intrusion in A Tropical Coastal Environment Using Radar and Optical Remote Sensing

The Alligator River Region (ARR) of the Northern Territory, Australia, has been identified as being particularly susceptible to saltwater intrusion. The Parks and Wildlife Commission of the Northern Territory (PWCNT) have attempted to restrict the intrusion and preserve the natural environment by creating physical earth barrages. A consequence of the intrusion is the conversion of freshwater paperbark (Melaleuca spp.) swamps into extensions of the mangrove margin. During this process stands of dead Melaleuca result and juvenile mangroves (primarily Avicennia marina) invade and establish in the affected areas. The use of Airborne Polarimetric Synthetic Aperture Radar (AirSAR) fused with Thematic Mapper (TM) is investigated as a means for mapping Melaleuca dieback as a measure of the extent of the saltwater intrusion. Individually the sensors cannot map areas of salt affected Melalecua as there is confusion with other cover types in the study area. The combined data set were evaluated for the most useful components of the optical and AirSAR data in resolving the overlap of land cover types and a map of Melalecua dieback was produced. A total of 0.4% of the Study Area or 2.25 square km was identified as being affected by recent saltwater intrusion with an aerial assessment yielding 100% accuracy. The individual areas range from 100 to 3100 square metres and are typically located along tidal creek lines or at the edge between floodplain and woodland. The high identification accuracy using this methodology may allow the use of Melalecua dieback as a bio-indicator of environmental change in tropical floodplain systems.

Fractionation of phosphate in sediments of four representative mangrove stages (French Guiana)

Phosphate was fractionated in Guianese mangrove sediments. Fe(OOH)≈P was extracted using a Ca-EDTA + Na-dithionite solution buffered at pH 8. CaCO3≈P was extracted using Na2-EDTA solution at pH 4.5. Next, Acid Soluble Organic Phosphate (ASOP) was extracted by H2SO4 0.5 N. Finally, Residual Organic Phosphate (ROP) was digested with H2SO4 + H2O2. Four representative mangrove stages have been studied: sea edge pioneer mangroves, mature coastal mangroves, mixed riverine mangroves, and declining to dead mangroves. The sum of the P-fractions varied between 638 to 804 μg g-1 in pioneer and mixed mangroves respectively. In all the stages, the percentage of inorganic phosphate was larger than 50% of the total P. Fe(OOH)≈P varied between 221 (pioneer mangrove) to 426 μg g-1 (dead mangrove). CaCO3≈P varied between 75 to 102 μg g-1 in mixed, dead or mature mangroves and attained 125 μg g-1 in pioneer mangrove. The sum of the concentrations of organic phosphate (ASOP + ROP) increased markedly from the dead mangrove (189 μg g-1) to the mixed mangrove (380 μg g-1). Guianese mangroves, are relatively rich in total phosphate, possibly because they are narrowly related to the 'Amazon dispersal system′. Each mangrove stage can be characterised by a prevailing form of phosphate. The concentrations of these different forms were ascribed to the marked relations with the seawater which controls import or export of suspended matters and to the wave action which controls the resuspension of the sediments and subsequently exchange of phosphate between the suspended matter and the water column.

The Galeta Oil Spill. II. Unexpected Persistence of Oil Trapped in Mangrove Sediments

Sediment chemistry studies, undertaken as part of the long-term assessment of the Bahı́a las Minas (Panamá) oil spill, showed the unexpected persistence of the full range of aromatic hydrocarbon residues of the spilled crude oil in anoxic muds of coastal mangroves. Mangrove muds served as long-term reservoirs for chronic contamination of contiguous coastal communities for over 5 years. One result of the repeated history of oil pollution incidents along this coast was an increased proportion of dead mangrove ( Rhizophora mangle) roots in sediment cores which was related to contaminant loading and was detectable for at least 20 years after major oil spills. We suggest that this is the minimum time-scale that is to be expected for the loss of toxicity of oil trapped in muddy coastal habitats impacted by catastrophic oil spills.

Leaf choice by crustaceans in a mangrove forest in Queensland

The feeding behaviour of leaf eating crustaceans feeding on leaves shed by Avicennia marina, Bruguiera gymnorhiza and Rhizophora stylosa in the mangrove forest at Myora Springs, Queensland, Australia was studied between 1980 and 1984. Individual Sesarma erythrodactyla (carapace >9 mm long), one of the most abundant species of crabs in the forest, processed approximately half a leaf from any of the three species of mangroves in 24 h under laboratory conditions. of the amount of leaf material processed, 20% was lost from the mandibles due to “sloppy feeding”, 68% was egested as faeces and 12% converted into crab biomass. Crabs processed more leaf material at 30°C than at 20°C. S. erythrodactyla preferred leaves of A. marina to those of the other two species, probably because leaves of A. marina have a lower tannin and a higher nitrogen content. Of the other two species, B. gymnorhiza was preferred to R. stylosa. Among leaves of R. stylosa, S. erythrodactyla exerts a strong preference for aged rather than freshly fallen, and for thick rather than thin leaves. The mesofauna (carapace length <9.0 mm) which processed dead mangrove leaves comprised juveniles of S. erythrodactyla, the crab Ilyograpsus paludicola, the isopod Exosphaeroma alata and the amphipods Orchestia sp. and Melita sp. These species processed between 0.2 and 24.7 mg dry wt of a leaf per individual over a period of 4 d. Of this, 72 to 85% was egested as faeces. The significance of leaf eating crabs to nutrient cycling in mangrove forests is discussed. I conclude that leaf processing by crustaceans shortens the time span between leaf fall and consumption of leaf material by organisms. This may have the effect of conserving leaf biomass inside the mangrove forest.

Leaching of dissolved organic carbon (DOC) from dead leaves, formation of flakes from DOC, and feeding on flakes by crustaceans in mangroves

Organic matter was released into sea water from dead mangrove leaves, under both biotic and abiotic conditions. Particulate matter (flakes) formed in the leachates under both conditions. Flakes cultured in the laboratory and flakes obtained from natural environments were colonized by microbial organisms and were utilized as food by copepods, amphipods, isopods, crabs and shrimps. This suggests an alternative pathway of energy transfer to that in the classical “plant-grazer-carnivore” communities. Since the leaching of organic matter from plant material and the formation of particulate matter from dissolved organic carbon are faster than the grazing of fallen leaves by metazoans, the alternative pathway may result in a faster rate of energy transfer from vascular plants to higher trophic levels than is found in grazer communities.

Carbon and nitrogen dynamics in decomposing leaves of three coastal marine vascular plants of the subtropics

Leaves of red mangrove ( Rhizophora mangle L.), needle rush ( Juncus roemerianus Scheele) and turtlegrass ( Thalassia testudinum Banks ex König) from litterbags were sampled by removal of pieces of measured volume, rather than, or in addition to, using the entire contents of bags as unit samples. Dead mangrove and turtlegrass leaves decomposed rapidly, approaching the point of full breakdown to fine-particulate and dissolved state within 6 months after litterbag placement. By contrast, net loss of dry matter from rush leaves after 2 years was about 50% or less. Net immobilization of nitrogen (0.1–0.7 mg cm −3 leaf month −1) occurred in mangrove leaves decaying in the summer, as established by use of the standard-volume sampling method. Rush and mangrove leaves decreased sharply in mean mass-ratio of carbon to nitrogen during decomposition, from about 75–125:1 to about 30–40:1. Turtlegrass leaves were consistently low in mean ratio of carbon to nitrogen (15–18:1). The measured-volume sampling, in comparison to whole-bag results, revealed that early losses of pieces of leaf by fragmentation were negligible for mangrove leaves. However, for turtlegrass leaves, which do not immediately die and decompose upon detachment, loss of leaf portions was apparently a major contributor to total dry-matter output. Rush leaves exhibited erratic rates of loss of dry matter as assessed with the measured-volume technique; significant increases in density of dry matter were recorded, apparently due to increases in ash content and to active infiltration by cyanobacteria.