Mangrove Leaf Research Articles

Human proximity suppresses fish recruitment by altering mangrove-associated odour cues

Human-driven threats to coastal marine communities could potentially affect chemically mediated behaviours that have evolved to facilitate crucial ecological processes. Chemical cues and their importance remain inadequately understood in marine systems, but cues from coastal vegetation can provide sensory information guiding aquatic animals to key resources or habitats. In the tropics, mangroves are a ubiquitous component of healthy coastal ecosystems, associated with a range of habitats from river mouths to coral reefs. Because mangrove leaf litter is a predictable cue to coastal habitats, chemical information from mangrove leaves could provide a source of settlement cues for coastal fishes, drawing larvae towards shallow benthic habitats or inducing settlement. In choice assays, juvenile fishes from the Caribbean (Belize) and Indo-Pacific (Fiji) were attracted to cues from mangroves leaves and were more attracted to cues from mangroves distant from human settlement. In the field, experimental reefs supplemented with mangrove leaves grown away from humans attracted more fish recruits from a greater diversity of species than reefs supplemented with leaves grown near humans. Together, this suggests that human use of coastal areas alters natural chemical cues, negatively affecting the behavioural responses of larval fishes and potentially suppressing recruitment. Overall, our findings highlight the critical links that exist between marine and terrestrial habitats, and the importance of considering these in the broader conservation and management of coastal ecosystems.

Bioaccumulation and biomagnification of potential toxic elements (PTEs): An Avicennia germinans–Uca rapax trophic transfer story from Jobos Bay, Puerto Rico

In southern Puerto Rico along the coastline bordering the Jobos Bay National Estuarine Research Reserve, environmental encroachment has exposed mangrove forest to different sources of pollution. Potentially toxic element concentrations from the F1Tess (exchangeable), F4Tess (oxidizable), mangrove leaf litter (MLL), and fiddler crab whole body soft tissue were analyzed to assess the fate and transport of pollutants from the environment and its transition into flora-fauna via trophic transfer. Geo-accumulation factor values suggest the bay has experienced limited to no pollution when combining the concentrations of potentially toxic elements extracted from the F1Tess and F4Tess sediment fractions. These geochemical sedimentary compartments are considered “bioavailable” to flora-fauna as evidenced by the bioaccumulated Cd-Ba-V-Cu-Zn-As-Se in the leaf litter of the black mangrove Avicennia germinans and in the fiddler crab Uca rapax. The biota-sediment accumulation factor (F1Tess + F4Tess) demonstrated that Uca rapax behave like a de-concentrator for most pollutants and as a macro-concentrator for Cu-As, while the bioconcentration factors identified only Cu-As-Se as being actively bioaccumulated in the fiddler crabs. Of all the potentially toxic elements studied, As is the only one to be biomagnified via sediment-Avicennia germinans leaf litter-Uca rapax food chain. An unexpected find of this study was that the excavated sediment “pellets” by Uca rapax contained up to 4x the concentrations of Cd-Ba-V-Cr-Co-Ni-Cu-Zn-As-Se when compared to the F1Tess sediment fraction from the surface, thus suggesting a variable redox boundary within the fiddler crab’s burrow.

Laju Dekomposisi Serasah Daun Mangrove Bruguiera gymnorrhiza dan Sonneratia alba di Kawasan Hutan Mangrove Pulau Penyu, Tanjung Benoa, Bali

Mangroves are plants that play an important role in maintaining the fertility of mangrove ecosystems by contributing organic material derived from leaf litter. The rate decomposition of leaf litter is a destruction process by dead organisms into smaller particles. The decomposition process of mangrove leaf is affected by lignin and wax in nitrogen supply, environmental conditions, abundance of organisms, and air temperature. This research aims to determine the decomposition rate of leaf litter and percentage decomposition of Bruguiera gymnorrhiza and Sonneratia alba in mangrove forest area in Penyu Island, Tanjung Benoa, Bali. This research was conducted from February to April 2017. The method in this research used litter trap method. The location of the stations was based on the distance of the mangrove trees to the sea. Litter traps were placed on the six (6) stations. During the 60 days of decomposition process, Sonneratia alba leaf was decomposed faster than Bruguiera gymnorrhiza. The highest decomposition rate of Sonneratia alba leaf litter found at station 1 (1.7 g/day) with 99.9% decomposed, and the lowest at station 2 (1.38 g/day) with 99.64% decomposed. The highest decomposition rate of Bruguiera gymnorrhiza leaf litter found at station 1 (1.52 g/day) with 98.88% decomposed, and the lowest at station 2 (0.99 g/day) with 84.66% decomposed.

An overview on Philippine estuarine oomycetes

Estuarine saprotrophic oomycetes are a group of eukaryotic, fungal-like protists of the Kingdom Straminipila. Species classified as estuarine oomycetes are commonly present on mangrove leaf litter and saltmarsh plant debris. They are distributed over several families (i.e. Peronosporaceae, Pythiaceae, Salisapiliaceae, and Salispinaceae). It is estimated that there are more than 100 species of estuarine oomycetes and, surprisingly, some supposedly terrestrial phytopathogenic hemibiotrophic oomycetes, e.g. Phytophthora elongata, Ph. insolita, and Ph. ramorum, are likewise present in the estuarine biome. In the Philippines, this group has been neglected for several decades as compared to the obligate biotrophic and hemibiotrophic members of Peronosporaceae and Albuginaceae. In this account, a general overview on the systematics and phylogeny of estuarine oomycetes is given. Further, the state of knowledge regarding thallus organization, taxonomy, habitat, and status of Philippine oomycetes are presented.

Identification of bacteria from mangrove forest in Mamburungan, Tarakan City

Bacteria has a main role in the food chain and waters productivity. Bacteria in the mangrove ecosystem mostly are from litter, sediment, and sea waters. The research objective is to determine the genus of bacteria that was found in Avicennia marina and Sonneratia alba leaf litter as well as bacteria in waters and sediment from a mangrove forest in Mamburungan. The method was designed by using explorative descriptive, and the analysis parameter was the genus. This study was done in the field experimentally with two phases; they were collected of mangrove leaf litter, waters, and sediment, followed by identification of bacteria in the Fish quarantine station, quality control, and safety of Tarakan Class II Fisheries Laboratory. The results showed that seven genus bacteria of Sonneratia alba was found, such as Bacillus, Aeromonas, Listeria, Stapylococcus, Enterobacteria, Bacteroides, Actinobacillus and nine genus of Avicennia marina, they were Bacillus, Listeria, Aeromonas, Pseudomonas, Enterobacteria, Corynebacterium, Actinobacillus, Plesiomonas, Flavobacterium. In sediment, there were ten genus, i.e., Bacillus, Plesiomonas, Enterobacteria, Corynebacterium, Listeria, Aeromonas, Micrococcus, Actinobacillus, Bordetella parapertussis, Clostridium. In sea waters, there were eight genus like Bacillus, Listeria, Aeromonas, Corynebacterium, Micrococcus, Actinobacillus, Pseudomonas, and Enterobacteria. The dominant bacteria that were found in litter, sediment, and sea waters were Bacillus.

Estimating the value of mangrove leaf litter in sesarmid crab diets: the importance of fractionation factors

Sesarmid crabs play an important role in organic matter and carbon cycling of mangrove forests. Visual observations and gut content studies have verified that sesarmid crabs are feeding on mangrove leaves, yet stable isotopes of carbon and nitrogen (13C and 15N) have indicated that leaf litter is not assimilated as a food source. Sesarmid crabs tend to be much more enriched in 13C than leaf litter (0.9‰ – 11.6‰) and have C values that are often more like microphytobenthos (MPB). General 13C trophic enrichment factors (TEF; 0.1‰ – 0.5‰) suggest crabs feed more heavily on MPB. Field and laboratory-based evidence reveal that general 13C TEF for crabs feeding on mangrove leaves may be incorrect and much greater than 0.1‰ – 0.5‰. A food web study conducted annually over 2 yrs revealed a shift in the δ13C and δ15N of Parasesarma sp. crabs similar to mangrove leaves also sampled. This suggested Parasesarma sp. may be feeding more heavily on mangrove leaves than previously reported despite crabs being 4.4‰ – 11.6‰ more enriched in 13C than mangrove leaves. A laboratory feeding study confirmed that average 13C TEF between Parasesarma sp. and decayed Rhizophora sp. leaves was 3.3‰ (SE 0.5). The Stable Isotope Analysis in R package (SIAR) used with our TEF and the general 0.5‰ 13C TEF revealed that published TEFs may underestimate mangrove leaf contributions to sesarmid crab diets on average by 33.3% (SE 0.1) and overestimate MPB and epiphytic algal contributions by 31.3% (SE 0.1). Food web studies in mangroves and other ecosystems will continue to inaccurately identify important food resources or food web structures unless more accurate and species-specific isotope fractionation values are determined.

Mangrove leaves with outstanding content of free amino acids especially GABA, makes them candidates for functional food

Herbal remedies by using mangrove plants have been recognized in several countries, and the plant materials are often consumed as a tea, which are infusions of dried plant parts steeped in boiling water. These infusions from mangrove plants are believed to be effective agents for treating and/or prevent infections, ailments, and diseases, and some mangrove plants have attracted attention as functional food resources in recent years. To reveal the beneficial properties of mangrove plants, clarification of the chemical ingredient and its characteristics of mangrove plants is required. This study focused on amino acids, which were functional ingredients (i.e., bioactive compounds) because amino acids are expected to function as ‘functional ingredients’ in addition to conventional ‘nutrients’ in recent years. To demonstrate the further possibilities of mangrove tea, we firstly evaluated the content of total amino acids in the leaf of several dominant mangrove species with commercial teas as references. Next, we clarified the composition of amino acids by using LC-MS analysis. As the results, free amino acid content (FAC) in leaf sample of Rhizophora stylosa, Bruguira gymnorrhiza, Kandelia obovata, Avicennia marina, Sonneratia alba, and Lumnitzera racemosa was 747, 1056, 946, 829, 623, and 896 mg/100 g DW, respectively. The FAC in all mangrove leaf samples were higher than those in green tea of low price, black tea, oolong tea, barley tea, and mate tea. Moreover, it was found that GABA accounts for over 10% of the total amino acid in the mangrove leaf samples. Especially in mature leaves of K. obovata, the ratio was very high levels 35%. In the case of K. obovata, the contents were higher than GABA tea. Based on this, we concluded that several mangrove plants, especially K. obovata has the potential of a functional food which is GABA-rich.

The effect of using different vegetation indices for mangrove leaf area index modelling

Spectral vegetation index (SVI) is a mathematical combination of image spectral bands, especially ranges from visible to near infrared portion of the light spectrum. The purpose of SVI is to emphasize the vegetation content information from an image and doesn’t directly correlate with any physical or bio-physical characteristics of vegetation. One of the important biophysical parameters of vegetation that can be derived from SVI is Leaf Area Index (LAI). LAI can be defined as one half the total green leaf area per unit horizontal ground surface area and considered as an indicator to determine the level of mangrove health. Various SVIs have been developed and different SVI affects the accuracy of the LAI model. This study aimed to (1) compare and contrast the performance of several SVIs applied to WorldView-2 (WV-2) image to estimate the LAI, and (2) find the most accurate model for estimating LAI of mangrove forest in Perancak Estuary, Bali. The SVI used are Simple Ratio (SR), Normalized Differenced Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Green Atmospherically Resistant Vegetation Index (GARI), dan Wide Dynamic Range Vegetation Index (WDRVI). The LAI models developed were based on the semi-empirical relationships between SVIs and field LAI measured from hemispherical photograph. The corresponding values of both parameters were correlated to find the regression function for the modelling. The results show that the best accuracy was obtained from NDVI which has an R2 value of 0.83 and an estimation accuracy of 89.10 %.

Protection Effect of Gray Mangrove Extract to Oxidative Stress after Mixed Periodontopathogen Bacteria Infection-Animal Models

Periodontitis is caused by periodontopathogenic bacterial infection. There is a relationship between Reactive Oxygen Species (ROS) and the pathogenesis of periodontitis. The imbalance between ROS and antioxidant trigger an oxidative stress response which causes periodontal destruction. Leaves of gray mangrove have been reported to possess antimicrobial, antioxidant, and anticandidal activities. The aim of this study is to investigate the protective effect of the gray mangrove leaf extract on the lipid peroxidation level and catalase activities in saliva periodontitis Wistar rats. The experiment was post-test only control group design. Thirty-five male Wistar rats divided randomly into five groups. 1st group (G1) was a negative control without treatment, 2nd group (G2) was a positive control that induced by mixed periodontopathogenic bacteria, and 3rd,4th,5th group (G3, G4, G5) induced by mixed periodontopathogenic bacteria and treated with gray mangrove leaf extract at dose 0.25 g/kg, 0.5 g/kg, and 1 g/kg daily, respectively. After treatment, the rats were sacrificed. Salivary malondialdehyde level (mg/mL) was measured by the thiobarbituric acid (TBA) method. Catalase activity (U/mL) was measured by optical density method. Data were analyzed one way ANOVA and Least Significant Difference (LSD) test (p

Mangrove leaf species-specific isotopic signatures along a salinity and phosphorus soil fertility gradients in a subtropical estuary

Mangrove ecotypes are distinct monospecific or mix-species assemblages and used as classification criteria to evaluate coastal biogeochemical cycles at the local, regional, and global scales. However, it is not clear how plant nitrogen and carbon content, including bulk δ13C and δ15N and n-alkane δ13C values, vary across species and within species when plants are exposed to the interaction between nutrient (nitrogen-N, phosphorus-P) availability and stressors (i.e., salinity). Here we present significant differences in green leaves wax n-alkane δ13C (δ13Cn-alkane) values and brown-senescent leaves C:N atomic ratios and total phosphorus (TP) concentrations of three mangrove species (Rhizophora mangle, Laguncularia racemosa, and Avicennia germinans) that reflect ecophysiological adaptations to nutrient availability and salinity along the Shark River estuary (SRE), South Florida, USA. Linear models between leaf wax δ13Cn-alkane values and species location along TP fertility and salinity gradients showed distinct differences, particularly between the species A. germinans and R. mangle. Our analyses showed that leaf wax δ13Cn-alkane properly represented major differences in ecophysiological responses by each mangrove species. We also found that both R. mangle and L. racemosa showed different isotopic footprints among the SRE upper, middle and lower estuarine salinity regions. Further, the green leaves bulk δ13C values in R. mangle (−32.3‰ to −27.6‰) were positively correlated with distance from the mouth of the estuary. In contrast, L. racemosa showed a negative relationship with distance and a narrower bulk δ13C range (−29.8‰ to −28.1‰) in comparison to the other two species. A. germinans, a species found only in the brackish (salinity: 18.8 ± 1.2) and saline (30.3 ± 0.53) estuarine regions, also showed a positive bulk δ13C relationship with distance. Because of the well-defined species-specific leaf wax n-alkane δ13C values along both water column/soil pore water salinity and TP gradients, we propose these values as a potential salinity proxy for paleoclimate reconstruction.

Understanding the fate of shrimp aquaculture effluent in a mangrove ecosystem: Aiding management for coastal conservation

Abstract Areas dedicated to shrimp aquaculture have increased dramatically over the last 50 years. Resultant land‐use changes directly threaten the extent of mangroves and yield conflicts on the discharge location of aquaculture effluent. Khung Krabaen Bay (KBB), Thailand, is reforesting mangroves while increasing the efficiency of shrimp aquaculture for local farmers. In this coupled shrimp farm–mangrove system, effective management requires understanding the fate of aquaculture organic matter (OM) in the coastal environment. We examined carbon and nitrogen stable isotope ratios (δ13C, δ15N) in primary producers and pools of particulate and sediment OM (POM, SOM) from the KKB mangrove and marine ecosystem to determine how shrimp aquaculture OM contributes to the coastal environment. Here, soy‐based shrimp feed resulted in low shrimp δ15N, similar to marine POM, and thus we focus on the use of δ13C in tracking shrimp pond effluent in the environment. δ13C signatures of SOM varied significantly along a land‐to‐ocean gradient (–29.1‰ to –23.9‰). We found consistently depleted mangrove SOM δ13C signatures (–29.4‰ to –28.2‰) indicating that mangrove leaf litter is the primary source of OM to mangrove sediments, and there is little evidence that marine and shrimp pond OM contributes to the mangrove habitat. In contrast, relatively low δ13C values for marine SOM (–25.7‰ to –23.9‰) overlap with the δ13C of shrimp feed (–25.3‰) and Bayesian mixing models indicate that shrimp aquaculture feed and mangrove vegetation contribute the greatest OM to the marine ecosystem. Compared to 20 years ago, marine SOM δ13C signatures are depleted by ~10‰ and similar throughout KKB, indicating a homogenization of marine SOM carbon sources from 1998 to 2018. Synthesis and applications. The doubling of shrimp aquaculture in Khung Krabaen Bay (KKB) since 1998 led to increased discharge to the bay, swamping organic matter (OM) contributions from 13C‐enriched seagrasses and marine plankton. Because of this increase in effluent release to KKB, the chemical impact is likely to be greater for the marine ecosystem than the mangrove and should also be a focus of conservation efforts. Continued technological improvements (e.g. closed systems, better feed efficiency) and support to local aquaculture farmers will help reduce OM discharge to coastal ecosystems and promote sustainable farming practices.

Changes in Leaf Litter Quality During Its Decomposition in a Tropical Planted Mangrove Forest (Can Gio, Vietnam)

Mangroves are highly productive ecosystems, being key components of trophic food chains along tropical coastlines. In Southern Vietnam, planted Rhizophora apiculata develops in the upper intertidal zone, while Avicennia alba naturally colonizes areas at lower elevation along tidal creeks. The main objective of this study was to quantify the seasonal variability of leaf litter decomposition rates considering that in previous studies we observed a strong influence of the monsoon on C and nutrients cycling within the mangrove and in adjacent creeks. We were also interested in changes in the quality of the leaf litter during its decomposition, focusing on nutrients, δ13C, and trace metals. To reach our goals, we used the litterbag technique. During the monsoon, leaf litter decay rates were increased in the Avicennia stand, most probably because of enhanced leaching resulting from a higher level of the river due to heavy rainfall. In addition, the enhanced decay rates measured in the Avicennia stand during the rainy season resulted in a strong 13C depletion, while 13C enrichment was measured in the other conditions. Elemental concentrations changes during decay were not clearly influenced by season, but depended on the element considered. K, Mg, Na, and Ca had t50 values lower than the one of the bulk material. P and S contents also rapidly decreased during the first decomposition stages, but these elements had longer t50 values than the bulk leaves. Conversely, an enrichment in most trace metals was observed during leaf litter decomposition whatever the season. We suggest that these metals were either trapped from the water column and the forest floor by organic molecules composing the litter, or subjected to litter decomposers uptake. Consequently, this study shows that the release or the uptake of elements during mangrove leaf litter decomposition varied with different parameters, which may have ecological implications on the nature of the elements exported toward adjacent ecosystems, and on their primary productivity.

THE EFFECT OF IMMERSION OF MANGROVE Avicennia alba (Tomlinson, 1986) LEAF EXTRACT WITH DIFFERENT CONCENTRATIONS IN PREVENTING BACTERIAL DISEASE Vibrio harveyi (Johnson & Shunk, 1936) IN VANAME SHRIMP (Litopenaeus vannamei) (Boone, 1931)

Vibriosis is a disease that often attack shrimp culture, some of the most dangerous types of Vibrio bacteria are V. harveyi. The use of natural materials is an alternative that can be applied to prevent bacterial disease. One of the mangrove species that has an antibacterial compound is A. alba. A. alba has alkaloid, saponins, and flavonoids compounds that can inhibit the function of cytoplasmic membranes and energy metabolism in bacteria. This study was conducted to determine the effectiveness of A. alba leaf extract A. alba in inhibiting V. harveyi disease in vaname shrimp (Litopenaeus vannamei). This research was conducted in several stages, namely extraction of mangrove leaves, both in vivo and in vitro. The highest SR, RPS and MTD values were obtamed at a concentration of 250 mg/l with each value of 80 %, 60 %, 75th respectively hour. Mangrove leaf extract A. alba was able to prevent diseases caused by the bacteria V. harveyi, with the best results at an extract concentration of 250 mg/l where the concentration can significantly higher SR, RPS, and MTD compared to other treatments.

Apoptotic with Double-Staining Test, P53, and Cyclooxygenase-2 to Proliferation Colon Cancer Cell (WiDr) of Dolichol in Three Mangrove Leaves

BACKGROUND: Mangroves secondary metabolites are mostly consisting of sterols, ubiquinones, isoprenoids, and polyisoprenoids. Polyisoprenoid is divided into two types, namely, polyprenol and dolichol, which has been reported to have biological and pharmacological activities.
 AIM: This research was aimed to analyze apoptosis 48 h with double staining and immunocytochemistry (ICC) 48 h of P53 and cyclooxygenase-2 (COX-2) gene expression from chemical constituents of dolichol in three mangrove leaves of Ceriops tagal, Nypa fruticans, and Rhizophora mucronata.
 METHODS: Apoptosis with the double-staining method was employed to analyze the genes expression in growth and development of cancer cells, P53, and COX-2 with ICC and flow cytometry method. The data were statistically analyzed using one-way ANOVA parametric statistical analysis followed by Duncan’s test.
 RESULTS: The result revealed that the increased apoptosis of samples C. tagal was 70% fluorescence orange, while N. fruticans and R. mucronata were 35% and 30% fluorescence orange, respectively. However, it was compared with the positive control; it produced orange fluorescent as much as 75%, suggesting that C. tagal have a position similar to 5-FU. Predominance dolichol in N. fruticans and C. tagal leaves led the expression gene of p53 to have 1.57% M1 phase, indicating the domination in G0-G1 phase (70–80%). Inhibit the expression for 48 h in p53 and COX-2 showing that n-hexane extract of C. tagal had the most percentage (80.733 ± 0.11%) to upregulate the p53 and less percentage (20.16 ± 1.19%) to downregulate the COX-2, indicating positive extract belong to N. fruticans and R. mucronata leaves.
 CONCLUSION: The present study confirmed the pharmacological properties of dolichol from three mangrove leaves as an anticancer of tumor suppressor genes and significantly proliferated of cancer cell growth from mangrove leaves.

Antibacterial activities of mangrove leaf endophytic fungi from Luzon Island, Philippines

Antibacterial activities of mangrove leaf endophytic fungi from Luzon Island, Philippines

The Amino Acid Contents in Mangrove Rhizophora mucronata Leaves in Asahan, North Sumatra, Indonesia

Amino acids are important components of mangrove plant metabolisms. The aim of this study was to determine the relationship of mangrove R. mucronata leaf colors to the amino acid content. This study was conducted between March to August 2019. The leaves were taken 50 g. The assessment of Amino acids was conducted using UPLC Waters Acquity Class H with PDA Detector. The principal component analysis (PCA) was used to determine the relationship analysis between R. mucronata leaf colors and amino acid concentrations. The largest content was L glutamic acid with a green leaf content of 6139.57 ± 694.17 mg/kg and yellow leaf content of 6105.013 ± 113.2058 mg/kg. The results of PCA 1 showed that the influential amino acids were L-threonine (0.94), L-tyrosine (0.96), L-alanine (0.92), L-vanin (0.93), and PCA 2 showed glutamic acid (0.91). These results indicated that the difference in mangrove leaf colors affects the amino acid contents in the leaves.

Quantifying how changing mangrove cover affects ecosystem carbon storage in coastal wetlands.

Despite overall global declines, mangroves are expanding into and within many subtropical wetlands, leading to heterogeneous cover of marsh-mangrove coastal vegetation communities near the poleward edge of mangroves' ranges. Coastal wetlands are globally important carbon sinks, yet the effects of shifts in mangrove cover on organic-carbon (OC) storage remains uncertain. We experimentally maintained black mangrove (Avicennia germinans) or marsh vegetation in patches (n=1,120, 3×3m) along a gradient in mangrove cover (0-100%) within coastal wetland plots (n=10, 24×42m) and measured changes in OC stocks and fluxes. Within patches, above and belowground biomass (OC) was 1,630% and 61% greater for mangroves than for recolonized marshes, and soil OC was 30% greater beneath mangrove than marsh vegetation. At the plot scale, above and belowground biomass increased linearly with mangrove cover but soil OC was highly variable and unrelated to mangrove cover. Root ingrowth was not different in mangrove or marsh patches, nor did it change with mangrove cover. After 11months, surface OC accretion was negatively related to plot-scale mangrove cover following a high-wrack deposition period. However, after 22months, accretion was 54% higher in mangrove patches, and there was no relationship to plot-scale mangrove cover. Marsh (Batis maritima) leaf and root litter had 1,000% and 35% faster breakdown rates (k) than mangrove (A.germinans) leaf and root litter. Soil temperatures beneath mangroves were 1.4°C lower, decreasing aboveground k of fast- (cellulose) and slow-decomposing (wood) standard substrates. Wood k in shallow soil (0-15cm) was higher in mangrove than marsh patches, but vegetation identity did not impact k in deeper soil (15-30cm). We found that mangrove cover enhanced OC storage by increasing biomass, creating more recalcitrant organic matter and reducing k on the soil surface by altering microclimate, despite increasing wood k belowground and decreasing allochthonous OC subsidies. Our results illustrate the importance of mangroves in maintaining coastal OC storage, but also indicate that the impacts of vegetation change on OC storage may vary based on ecosystem conditions, organic-matter sources, and the relative spatiotemporal scales of mangrove vegetation change.

Effects of the Bioturbating Marine Yabby Trypaea australiensis on Sediment Properties in Sandy Sediments Receiving Mangrove Leaf Litter

Laboratory mesocosm incubations were undertaken to investigate the influence of burrowing shrimp Trypaea australiensis (marine yabby) on sediment reworking, physical and chemical sediment characteristics and nutrients in sandy sediments receiving mangrove (Avicennia marina) leaf litter. Mesocosms of sieved, natural T. australiensis inhabited sands, were continually flushed with fresh seawater and pre-incubated for 17 days prior to triplicates being assigned to one of four treatments; sandy sediment (S), sediment + yabbies (S+Y), sediment + leaf litter (organic matter; S+OM) and sediment + yabbies + leaf litter (S+Y+OM) and maintained for 55 days. Mangrove leaf litter was added daily to treatments S+OM and S+Y+OM. Luminophores were added to mesocosms to quantify sediment reworking. Sediment samples were collected after the pre-incubation period from a set of triplicate mesocosms to establish initial conditions prior to the imposition of the treatments and from the treatment mesocosms at the conclusion of the 55-day incubation period. Yabbies demonstrated a clear effect on sediment topography and leaf litter burial through burrow creation and maintenance, creating mounds on the sediment surface ranging in diameter from 3.4 to 12 cm. Within S+Y+OM sediments leaf litter was consistently removed from the surface to sub-surface layers with only 7.5% ± 3.6% of the total mass of leaf detritus added to the mesocosms remaining at the surface at the end of the 55-day incubation period. Yabbies significantly decreased sediment wet-bulk density and increased porosity. Additionally, T. australiensis significantly reduced sediment bio-available ammonium (NH4+bio) concentrations and altered the shape of the concentration depth profile in comparison to the non-bioturbated mesocosms, indicating influences on nutrient cycling and sediment-water fluxes. No significant changes for mean apparent biodiffusion coefficients (Db) and mean biotransport coefficients (r), were found between the bioturbated S+Y and S+Y+OM mesocosms. The findings of this study provide further evidence that T. australiensis is a key-species in shallow intertidal systems playing an important role as an ‘ecosystem engineer’ in soft-bottom habitats by significantly altering physical and chemical structures and biogeochemical function.

Source of organic detritus and bivalve biomass influences nitrogen cycling and extracellular enzyme activity in estuary sediments

In aquatic ecosystems, natural processes that remove nitrogen from the biologically available pool (e.g. denitrification) have been intensively studied as an ecosystem function that reduces eutrophication. The quantity of sediment organic matter is a key driver of denitrification with percent organic content positively related to rates of nitrogen removal; however, few studies have investigated the influence of the quality of organic matter on nitrogen cycling in estuarine sediments despite shifts in primary producers with eutrophication. This laboratory study using intact benthic communities investigates the influence of various organic detritus sources, which vary in their C:N ratio, on nitrogen gas (N2) and solute fluxes and extracellular enzyme activity in estuarine sediments. A custom-built tank with a removable front plate was used with a planar optode film to image sediment oxygenation. Mangrove leaf detritus significantly increased the net N2 production in sediments, while the deposition of other detrital sources and control sediments produced net N2 consumption. Sulfatase activity was significantly reduced in the mangrove leaves and seagrass treatments, suggesting alteration of heterotrophic microbial activity with reducing oxygen conditions. Leucine aminopeptidase activity, indicating nitrogen cycling, was reduced in all treatments, suggesting the organic detritus provided a nitrogen supplement or reduced the activity of extracellular enzymes producing microbes. Bivalve biomass increased net nitrogen gas fluxes in some treatments. Our results indicate different detrital sources may have varying impacts on the removal of bioavailable nitrogen through denitrification and show that feedbacks in biogeochemical cycles may occur with changes in organic detrital source pools.

The Addition of Mangrove Leaf Extract Rhizophora apiculata in White Shrimp (Litopenaeus vannamei) for Vibriosis Prevention

White shrimp is a brackish water commodity which is a solution to approve tiger shrimp (Penaeus monodon) which improves quality. One of the challenges in the cultivation of white shrimp is the attack of vibriosis, caused by the vibrio genus species V. parahaemolyticus. Rhizophora apiculata mangrove leaf extract with different dosages in white shrimp feed to increase vibriosis. Shrimp were given mangrove leaf extract for 40 days and were challenged for 7 days in a 40cm x 30cm x 28cm container, 20 heads/20 liter volume container. The study was conducted in 5 training, control + (Feed without extract + Infection), control- (feed without extract), P3 (0,5% + Infection), P4 (1% extract + Infection), P5 (2% extract + Infection ), the injected bacterial dose is 0.1 ml/heads density of 106 cfu/ml. The results showed that administration of mangrove leaf extract at a dose of 2% was able to maintain SR of 76,67%, increasing shrimp THC by 7,55í—106 cells/ml and DHC (hyaline cells 84,3% and granular 15,3%) which plan in the shrimp immune system. The number of bacteria and the amount of vibrio in the intestine is, 64,7í—108 cfu/ml and 16í—108 cfu/ml. Based on the results of the study, the use of mangrove leaf extract can be used in the cultivation of white shrimp as an immunostimulant because it can increase survival, THC, DHC and reduce bacteria in the intestines of white shrimp. Keywords: extracts, mangrove leaves, vibriosis, white shrimp, feed.