重金属Cd胁迫对红树蚬的抗氧化酶、消化酶活性和MDA含量的影响

摘要：本文在实验室条件下,观测不同Cd胁迫处理（时间和水平）对红树蚬（Geloina coaxans (Gmelin)）的胃组织中超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性、丙二醛(MDA)含量,及淀粉酶、脂肪酶和蛋白酶等3种消化酶活性的影响效应。结果表明,高浓度组（4.00 mg?L-1和8.00 mg?L-1）在较短的暴露时间即出现SOD 活性显著诱导,而低浓度组则需要更长的暴露时间。所有处理组的CAT活性均先受诱导而后抑制,但去除胁迫后低浓度组活性上升,高浓度组则持续下降。低浓度处理组在胁迫初期MDA含量上升,但随后下降至较低水平;高浓度处理组MDA含量上升稍为滞后,但随后上升至较高水平。在消化酶方面,Cd对红树蚬胃组织淀粉酶的影响基本上表现为抑制;在胁迫初期脂肪酶活性受到显著诱导,随着胁迫时间延长酶活性则下降,同时胁迫解除后不同程度恢复;对蛋白酶的影响效应规律性不明显。显著的效应-剂量间相关关系存在于特定时间的SOD活性（1d）,CAT、淀粉酶活性和MDA含量（7d和恢复6d）。本文还探讨了这些指标作为生物标记物应用于监测海洋重金属污染的可能性。 关键词：红树林;红树蚬;Cd胁迫;消化酶;抗氧化酶;脂质过氧化     

Mangrove leaf litter decomposition under mangrove forest stands with different levels of pollution in the Niger River Delta,Nigeria

Nutrient cycling often moves between litter fall and decomposition. It is hypothesized that hydrocarbon pollution will slow down mangrove litter decomposition because of the reduction in microbial activities. We studied decomposition rates at different levels of pollution (i.e. high and low) and amongst different mangrove species (i.e. red, white and black). For the first experiment, fresh leaves of Rhizophora racemosa were collected, sealed in a litter bag and placed on the mangrove floor for 1.24 years at which all the leaves had completely decomposed to humus and were oven‐dried and weighed to calculate the decomposition rate constant (k) of mass loss. Although there was no significant difference in the rate of decomposition (P > 0.05), leaves at the highly polluted plot had lower rate of decomposition (6.58 × 10^?4) when compared to leaves at the lowly polluted plot (1.75 × 10^?3). In the second experiment, there was a significant difference in decomposition rates amongst species (P < 0.05). Red mangrove leaves (0.41) decomposed more than white (0.28) and black (0.28) mangrove leaves. This implies that hydrocarbon pollution slowed, but did not stop the decomposition of mangrove leaves.     

Accumulation and distribution of heavy metals in a simulated mangrove system treated with sewage

Constructed tide tanks were used to examine the accumulation and distribution of heavy metals in various components of a simulated mangrove ecosystem. Young Kandelia candel plants grown in mangrove soils were irrigated with wastewater of various strengths twice a week for a period of one year. The amounts of heavy metals released via tidal water and leaf litter were monitored at regular time intervals. The quantities of heavy metals retained in mangrove soil and various plant parts were also determined. Results show that most heavy metals from wastewater were retained in soils with little being uptake by plants or released into tidal seawater. However, the amounts of metals retained in plants on a per unit dry weight base were higher than those in soils as the biomass production from the young mangrove plants was much smaller when compared to the vast quantity of soils used in this study. A significantly higher heavy metal content was found in roots than in the aerial parts of the mangrove plant,indicating that the roots act as a barrier for metal translocation and protect the sensitive parts of the plant from metal contamination. In both soil and plant, concentrations of Zn, Cd, Pb and Ni increased with the strengths of wastewater, although the bioaccumulation factors for these metals decreased when wastewater strengths increased. These results suggest that the mangrove soil component has a large capacity to retain heavy metals, and the role of mangrove plants in retaining metals will depend on plant age and their biomass production. This revised version was published online in August 2006 with corrections to the Cover Date.     

Nitrogen limitation of growth and nutrient dynamics in a disturbed mangrove forest,Indian River Lagoon,Florida

The objectives of this study were to determine effects of nutrient enrichment on plant growth, nutrient dynamics, and photosynthesis in a disturbed mangrove forest in an abandoned mosquito impoundment in Florida. Impounding altered the hydrology and soil chemistry of the site. In 1997, we established a factorial experiment along a tree-height gradient with three zones, i.e., fringe, transition, dwarf, and three fertilizer treatment levels, i.e., nitrogen (N), phosphorus (P), control, in Mosquito Impoundment 23 on the eastern side of Indian River. Transects traversed the forest perpendicular to the shoreline, from a Rhizophora mangle-dominated fringe through an Avicennia germinans stand of intermediate height, and into a scrub or dwarf stand of A. germinans in the hinterland. Growth rates increased significantly in response to N fertilization. Our growth data indicated that this site is N-limited along the tree-height gradient. After 2 years of N addition, dwarf trees resembled vigorously growing saplings. Addition of N also affected internal dynamics of N and P and caused increases in rates of photosynthesis. These findings contrast with results for a R. mangle-dominated forest in Belize where the fringe is N-limited, but the dwarf zone is P-limited and the transition zone is co-limited by N and P. This study demonstrated that patterns of nutrient limitation in mangrove ecosystems are complex, that not all processes respond similarly to the same nutrient, and that similar habitats are not limited by the same nutrient when different mangrove forests are compared.     

The multigenerational effects of water contamination and endocrine disrupting chemicals on the fitness of Drosophila melanogaster

Water pollution due to human activities produces sedimentation, excessive nutrients, and toxic chemicals, and this, in turn, has an effect on the normal endocrine functioning of living beings. Overall, water pollution may affect some components of the fitness of organisms (e.g., developmental time and fertility). Some toxic compounds found in polluted waters are known as endocrine disruptors (ED), and among these are nonhalogenated phenolic chemicals such as bisphenol A and nonylphenol. To evaluate the effect of nonhalogenated phenolic chemicals on the endocrine system, we subjected two generations (F0 and F1) of Drosophila melanogaster to different concentrations of ED. Specifically, treatments involved wastewater, which had the highest level of ED (bisphenol A and nonylphenol) and treated wastewater from a constructed Heliconia psittacorum wetland with horizontal subsurface water flow (He); the treated wastewater was the treatment with the lowest level of ED. We evaluated the development time from egg to pupa and from pupa to adult as well as fertility. The results show that for individuals exposed to treated wastewater, the developmental time from egg to pupae was shorter in individuals of the F1 generation than in the F0 generation. Additionally, the time from pupae to adult was longer for flies growing in the H. psittacorum treated wastewater. Furthermore, fertility was lower in the F1 generation than in the F0 generation. Although different concentrations of bisphenol A and nonylphenol had no significant effect on the components of fitness of D. melanogaster (developmental time and fertility), there was a trend across generations, likely as a result of selection imposed on the flies. It is possible that the flies developed different strategies to avoid the effects of the various environmental stressors.     

Removal of nutrients and heavy metals from wastewater with mangrove Sonneratia apetala Buch-Ham

Mangrove wetlands are important in the removal of nutrients, heavy metals, and organic pollutants from wastewater within estuarine systems due to the presence of oxidized and reduced conditions, periodic flooding by incoming and outgoing tides, and high clay and organic matter content. This study investigated the removal efficiency of nutrients and heavy metals from wastewater by the mangrove Sonneratia apetala Buch-Ham in a simulated wetland. Eight different treatments, namely, three concentration levels of wastewaters, with and without planting of the mangrove species, and one control (with salted water) each for both with and without planting of the mangrove species, were employed in this study. Results showed that the amounts of total mangrove biomass from different treatments were in the following order: PL-TW (planted with ten times higher-than-normal wastewater concentration) > PL-FW (planted with five times higher-than-normal wastewater concentration) > PL-SW (planted with normal wastewater concentration) > PL-NW (planted with no wastewater), whereas the magnitude of the heavy metal contents in the biomass was in the following order: Cu > Pb > Cd > Zn. Very good linear correlations existed between the biomass and the nutrients or heavy metals. The Sonneratia apetala Buch-Ham species had its own selectivity for uptake of heavy metals regardless of the initial heavy metal contents and was more effective in the removal of nutrients than heavy metals. Our study suggested that mangrove wetlands with Sonneratia apetala Buch-Ham species had great potential for the removal of nutrients and heavy metals in coastal areas.     

Classical and biochemical endpoints in the evaluation of phytotoxic effects caused by the herbicide trichloroacetate

Three terrestrial plant species, oat (Avena sativa ), Chinese cabbage (Brassica campestris cv. chinensis) and lettuce (Lactuca sativa), were exposed to different concentrations of herbicide TCA (sodium trichloroacetate) in a growth test according to guideline OECD # 208. Classical (i.e. germination and biomass) and biochemical (i.e., antioxydant enzyme activities) endpoints were investigated. Germination rate decreased significantly at 3.9 mg TCA kg dry soil(-1) (for oat and lettuce) and 62.5 mg TCA kg dry soil(-1) (for Chinese cabbage). Biomass decreased significantly only at 1.9 mg TCA kg dry soil(-1) (for oat and lettuce) and 15.6 mg TCA kg dry soil(-1) (for Chinese cabbage). The activities of superoxide dismutase (EC 1.15.1.1), catalase (EC 1.11.1.6), peroxidase (EC 1.11.1.7) and glutathione reductase (EC 1.6.4.2) increased significantly at the lowest concentration of TCA tested, i.e. 0.03 mg TCA kg dry soil(-1) (for oat and lettuce) and 0.48 mg TCA kg dry soil(-1) (for Chinese cabbage). Our results showed a ranking of sensitivity among the different endpoints for the three plant species: enzyme activities>biomass>germination rate. The increase in antioxidant enzyme activities observed in this study ensured the detoxification of increased levels of active oxygen species, and presumably prevented the plants from undergoing oxidative stress damage. Thus, the use of enzyme activities will permit the detection of early injury in plant growth testing.     

Use of beta-D-galactosidase and beta-D-glucuronidase activities for quantitative detection of total and fecal coliforms in wastewater

Two enzymatic methods based on the measurement of the beta-D-galactosidase activity of total coliforms and the beta-D-glucuronidase activity of Escherichia coli were used to assess coliform levels in wastewater alongside traditional culture-based techniques, which can be biased by the aggregation of bacteria or their attachment to particles. Enzymatic methods were precise (i.e., coefficients of variation were 9%-15%), rapid (response in 20 min), and correlated well (in log units) with traditional techniques for raw and treated sewage (r2 > 0.75). They were used for rapid assessment of coliform removal efficiency in two different wastewater treatments. These methods could be useful for the estimation of the abundance of coliforms in domestic sewage and their removal by wastewater treatment processes.     

Will fluctuations in salt marsh–mangrove dominance alter vulnerability of a subtropical wetland to sea‐level rise?

To avoid submergence during sea‐level rise, coastal wetlands build soil surfaces vertically through accumulation of inorganic sediment and organic matter. At climatic boundaries where mangroves are expanding and replacing salt marsh, wetland capacity to respond to sea‐level rise may change. To compare how well mangroves and salt marshes accommodate sea‐level rise, we conducted a manipulative field experiment in a subtropical plant community in the subsiding Mississippi River Delta. Experimental plots were established in spatially equivalent positions along creek banks in monospecific stands of Spartina alterniflora (smooth cordgrass) or Avicennia germinans (black mangrove) and in mixed stands containing both species. To examine the effect of disturbance on elevation dynamics, vegetation in half of the plots was subjected to freezing (mangrove) or wrack burial (salt marsh), which caused shoot mortality. Vertical soil development was monitored for 6 years with the surface elevation table‐marker horizon system. Comparison of land movement with relative sea‐level rise showed that this plant community was experiencing an elevation deficit (i.e., sea level was rising faster than the wetland was building vertically) and was relying on elevation capital (i.e., relative position in the tidal frame) to survive. Although Avicennia plots had more elevation capital, suggesting longer survival, than Spartina or mixed plots, vegetation type had no effect on rates of accretion, vertical movement in root and sub‐root zones, or net elevation change. Thus, these salt marsh and mangrove assemblages were accreting sediment and building vertically at equivalent rates. Small‐scale disturbance of the plant canopy also had no effect on elevation trajectories—contrary to work in peat‐forming wetlands showing elevation responses to changes in plant productivity. The findings indicate that in this deltaic setting with strong physical influences controlling elevation (sediment accretion, subsidence), mangrove replacement of salt marsh, with or without disturbance, will not necessarily alter vulnerability to sea‐level rise.     

土壤养分水平影响绢毛匍匐委陵菜匍匐茎生物量投资

为研究匍匐茎草本植物对基质养分供应水平的生物量分配格局的可塑性,在一盆栽实验中对绢毛匍匐委陵菜(Potentilla reptans var. sericophylla)进行了8种不同的养分处理。绢毛匍匐委陵菜植株生物量、匍匐茎数、分株数以及匍匐茎节间长在中等养分条件下最大。随土壤养分的降低,绢毛匍匐委陵菜对叶片和叶柄的生物量投资减小,而对根系的生物量投资增加。在中等养分条件下,绢毛匍匐委陵菜对匍匐茎的生物量投资倾向于最大,而在更高或更低的养分条件下倾向于减少。此生物量分配格局与de Kroon和Schieving的模型模拟结果相符合,结果表明在中等资源水平下增加对匍匐茎的生物量投资是克隆植物增加资源获取的对策之一。     

Effects of pharmaceutical products and municipal wastewaters on temperature-dependent mitochondrial electron transport activity in Elliptio complanata mussels

The advent of global warming has given rise to the issue on how temperature impacts the susceptibility of ectothermic organisms to pollution. The purpose of this study was to examine the effects of pharmaceutical products and domestic wastewaters on temperature-dependent mitochondrial electron transport activity in the freshwater mussel Elliptio complanata. Mitochondria from mussels were freshly prepared and exposed to increasing concentrations of various pharmaceutical products known to be found in municipal effluents for 30 min at 4, 12 and 20 degrees C. Electron transport activity as well as lipid peroxidation and DNA strand breaks were determined in the mitochondria. Next, mussels were placed in the aeration lagoons of two municipal wastewater treatment plants for 30 days. Mitochondrial electron transport (MET), temperature-dependent MET (MET(T)) and lipid peroxidation in gonad were then determined. The results show that all products were able to increase MET activity, but at two different ranges of threshold concentration. Certain pharmaceutical products (i.e., ibuprofen, cotinine, fluoxetine, coprostanol and trimethoprim) increased MET(T) at a lower threshold concentration than observed at 20 degrees C. Products of lesser potency in reducing lipid peroxidation were those that produced more DNA strand breaks in mitochondria. Both MET and MET(T) were significantly increased in mussels exposed to aeration lagoon effluents. Lipid peroxidation was also increased in the gonad and was significantly correlated with MET and MET(T) activities. The data indicate that pharmaceutical products and municipal effluents increase respiration rates in isolated mitochondria, such that interaction with temperature could enhance the susceptibility of mitochondrial energy production and oxidative stress in environments contaminated by domestic wastewater.     

Physiological adaptability of three mangrove species to salt stress

The impact of salinity on three arboreal mangrove plants, Sonneratia apetala (Sa), S. caseolaris (Sc) and Rhizophora stylosa (Rs), was studied. The three mangrove species were treated with different salinity levels over a three-month period. The response and adaptation of these three mangrove species to salinity were shown to be different. Net photosynthesis rate, stomata conductance and transpiration rate of leaves decreased and soluble sugar content in leaves increased, with salt concentration in all three mangrove species. The malondial dehyde (MDA) content in stems and leaves of Sa and Sc somewhat decreased when the salinity was lower than 10, but rapidly increased with increasing salt concentration. The MDA content in stems and leaves of Rs increased only when salinity was greater than 40. No changes were observed in the MDA content of roots in the three mangrove species. The adaptabilities of Sa and Sc to salt tolerance were limited. The more salt tolerant the mangrove Rs, the more likely the free oxygen radicals were eliminated through the increase in activity of superoxide dismutase (SOD). Results of this experiment identified salinity levels best suited for the growth and metabolism of the species, which provides information necessary for maintaining mangrove forestation along the South China coast.     

Physiological adaptability of three mangrove species to salt stress

The impact of salinity on three arboreal mangrove plants, Sonneratia apetala (Sa), S. caseolaris (Sc) and Rhizophora stylosa (Rs), was studied. The three mangrove species were treated with different salinity levels over a three-month period. The response and adaptation of these three mangrove species to salinity were shown to be different. Net photosynthesis rate, stomata conductance and transpiration rate of leaves decreased and soluble sugar content in leaves increased, with salt concentration in all three mangrove species. The malondial dehyde (MDA) content in stems and leaves of Sa and Sc somewhat decreased when the salinity was lower than 10, but rapidly increased with increasing salt concentration. The MDA content in stems and leaves of Rs increased only when salinity was greater than 40. No changes were observed in the MDA content of roots in the three mangrove species. The adaptabilities of Sa and Sc to salt tolerance were limited. The more salt tolerant the mangrove Rs, the more likely the free oxygen radicals were eliminated through the increase in activity of superoxide dismutase (SOD). Results of this experiment identified salinity levels best suited for the growth and metabolism of the species, which provides information necessary for maintaining mangrove forestation along the South China coast.     

Effect of wastewater discharge on root anatomy and radial oxygen loss (ROL) patterns of three mangrove species in southern China

The effects of wastewater discharge on radial oxygen loss (ROL) and root anatomy varied among mangrove species. ROL of Bruguiera gymnorrhiza (L) increased from 22.44 ng cm(-2) min(-1) in the control (just fresh water) to 31.09 ng cm(-2) min(-1) when received normal wastewater (NW) and to 44.22 ng cm(-2) min(-1) when treated with strong wastewater (10NW). However, discharge of both NW and 10NW caused 28% decreases of ROL in the root tip of Excoecaria agallocha L., and the decreases in Acanthus ilicifolius L were even more significant, with 45% when treated by 10NW The changes of ROL were related to the root anatomy. Among three species, A. ilicifolius had the highest proportional cross-sectional area of aerenchyma air spaces, suggesting that the internal oxygen transfer to root tip was the fastest. However, the area of aerenchyma air spaces in the root tip of 10NW treated A. ilicifolius was significantly reduced while area of epidermis and hypodermis (E + H) increased leading to less oxygen supply to root tip. Compared to B. gymnorrhiza and E. agallocha, the (E + H) layer of A. ilicifolius was the thinnest, and the cells without suberized walls were loosely packed in all three treatments. These results suggested that the root anatomy and ROL of B. gymnorrhiza was least affected by wastewater discharge, followed by E. agallocha, and A. ilicifolius was the most susceptible species thus was not suitable for treating strong wastewater.     

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.     

Effects of planting patterns on heavy metals (Cd,As) in soils following mangrove wetlands restoration

Abstract

To understand how planting patterns influence As and Cd in soils, the pollution grade release risk and fractions of As and Cd in soils from Jinjiang Estuary wetland were investigated. The geoaccumulation index (I_geo) and risk assessment code (RAC) were used to identify pollution grades and reveal the potential ecological risk of trace metals, respectively. The results showed that the ratios of the acid soluble fraction of Cd in the mangrove area (～65%) were larger than that of the control group (～31%). The residual fraction of As in the mangrove area (～74%) was also larger than that of the control group (～66%). Therefore, the planting of vegetation increased the mobility of Cd and decreased the mobility of As. Variance analysis showed that the total concentrations and fraction of As and Cd significantly differed among various vegetation types and planting densities. Thus, planting patterns might influence the transformation of trace metal fractions in soil, influencing the total concentrations of As and Cd. Furthermore, mangrove reforestation improved the pollution levels of As and Cd and increased the potential release risk of Cd. The study advances current knowledge on the importance of restoring wetland vegetation, providing suggestions on feasible planting patterns.     

Hydrological Classification,a Practical Tool for Mangrove Restoration

Mangrove restoration projects, aimed at restoring important values of mangrove forests after degradation, often fail because hydrological conditions are disregarded. We present a simple, but robust methodology to determine hydrological suitability for mangrove species, which can guide restoration practice. In 15 natural and 8 disturbed sites (i.e. disused shrimp ponds) in three case study regions in south-east Asia, water levels were measured and vegetation species composition was determined. Using an existing hydrological classification for mangroves, sites were classified into hydrological classes, based on duration of inundation, and vegetation classes, based on occurrence of mangrove species. For the natural sites hydrological and vegetation classes were similar, showing clear distribution of mangrove species from wet to dry sites. Application of the classification to disturbed sites showed that in some locations hydrological conditions had been restored enough for mangrove vegetation to establish, in some locations hydrological conditions were suitable for various mangrove species but vegetation had not established naturally, and in some locations hydrological conditions were too wet for any mangrove species (natural or planted) to grow. We quantified the effect that removal of obstructions such as dams would have on the hydrology and found that failure of planting at one site could have been prevented. The hydrological classification needs relatively little data, i.e. water levels for a period of only one lunar tidal cycle without additional measurements, and uncertainties in the measurements and analysis are relatively small. For the study locations, the application of the hydrological classification gave important information about how to restore the hydrology to suitable conditions to improve natural regeneration or to plant mangrove species, which could not have been obtained by estimating elevation only. Based on this research a number of recommendations are given to improve the effectiveness of mangrove restoration projects.     

Hydrogen peroxide concentrations in leaves under natural conditions

While H2O2 has been implicated in numerous plant environmental responses, normal levels and variabilities are poorly established, and estimates of leaf tissue concentrations span more than three orders of magnitude, even in a single species under similar conditions. Here, leaf tissue H2O2 contents under natural conditions are reported after determining (i) that H2O2 in extracts was stable with time, (ii) that H2O2 added to the extract was recovered quantitatively, and (iii) that the H2O2 calibration curve was unaffected (or quantifiably affected) by the extract. The broad applicability of the protocol and variability in leaf concentrations were demonstrated using tissue collected from several habitats in association with three, more extensive, experiments. The first involved nychthemeral studies of the mangrove, Rhizophora mangle L. Lowest H2O2 levels occurred in the early morning and near sunset, with higher levels both at midday and at night. Second, using five temperate species in Spring, concentrations were compared on a warm, sunny day and a cool, cloudy day. Higher concentrations were found on the warm day for Aesculus glabra Willd., Glechoma hederacea L., Plantago major L., and Viola soraria Willd., while there were no differences in Quercus macrocarpa Michx. Finally, the effects of elevated CO2 and ozone were examined in soybean, Glycine max L. Pioneer 93B15 under Free Air gas Concentration Enrichment (FACE) conditions. Both supplements led to elevated H2O2. Overall, mean leaf, midday, and mid-summer H2O2 concentrations ranged from 0.67 micromol (gFW)(-1) in mangrove to 3.6 micromol (gFW)(-1) in A. glabra Willd. Greatest within-species differences were only 2.5-fold in any of the studies.     

Effects of the physical structure of mangrove vegetation on a benthic faunal community

Clarification of the role of the physical structure of mangrove for benthic faunal communities was sought by investigating the impacts of canopy shade and root structure on (1) the physical environment, including temperature, moisture and grain size of the substrate sediment, (2) benthic faunal distribution, and (3) food resource availability, using a field manipulated experiment at an intertidal mangrove forest around Sikao Creek, Trang Province, Thailand. Five treatments were established, including artificial shade cover, root simulated structure, mix (shade and structure) and control of the canopy gap (which had no mangrove vegetation), in addition to forest control under the mangrove canopy. Following 18 months of observation, species' richness and abundance of epifauna were found to have increased in shaded treatments, which had low temperature and high moisture substrate. Food resource conditions had also altered from abundant microphytobenthos (relatively high nutritional values) to enriched mangrove detritus due to shading. These results indicated that the physical structure of mangrove vegetation facilitates the habitation of intertidal epifauna, canopy shade having an important function in providing cooler wetter surface substrate, despite also inducing a reduction of favorable food resources (i.e. microphytobenthos).