A framework to quantitatively assess the influence of land use and land cover on coastal wetland hydrological connectivity from a landscape resistance perspective.

Land use and land cover (LULC) change is one of the dominant factors contributing to coastal wetland degradation and loss. Most studies focused on LULC changes or whether they influenced on ecosystems. However, few studies quantitatively assessed the impact of different LULCs on hydrological connectivity. This study aimed to understand how LULC affected hydrological connectivity in the coastal wetlands in the Yellow River Delta (YRD), China, from 1985 to 2020. A framework from a landscape resistance perspective was used to evaluate the LULC's influence. LULCs were converted into a series of resistance surfaces whose values represent the degree to which LULC facilitated or restricted hydrological connectivity. The LULC's influence was evaluated by parameterizing the resistance surfaces using observed hydrological connectivity. The results showed that human-related LULC had more influence on hydrological connectivity. The critical time of LULC's influence on hydrological connectivity was 1985-1990 and 2010-2015. The critical areas were Zone II, Zone I, and Zone VI. The LULCs of agriculture, industry, town/city, and river had the most significant impact on the hydrological connectivity of the YRD coastal wetland. The result could direct LULC planning to mitigate the negative effect on coastal wetlands and provide support for the environmental impact assessment of coastal development practices. This paper advances the study by assessing LULCs' impact on hydrological connectivity and providing a quantitative method. The framework of this study enriches the coastal wetland conservation theory and policy-making of coastal management.

The importance of structural and functional characteristics of tidal channels to smooth cordgrass invasion in the Yellow River Delta, China: Implications for coastal wetland management.

Understanding the spatiotemporal landscape dynamics and spread pathways of invasive plants, as well as their interactions with geomorphic landscape features, are of great importance for predicting and managing their future range-expansion in non-native habitats. Although previous studies have linked geomorphic landscape features such as tidal channels to plant invasions, the potential mechanisms and critical characteristics of tidal channels that affect the landward invasion by Spartina alterniflora, an aggressive plant in global coastal wetlands, remain unclear. Here, using high-resolution remote-sensing images of the Yellow River Delta from 2013 to 2020, we first quantified the evolution of tidal channel networks by analyzing the spatiotemporal dynamics of their structural and functional characteristics. The invasion patterns and pathways of S. alterniflora were then identified. Based on the above-mentioned quantification and identification, we finally quantified the influences of tidal channel characteristics on S. alterniflora invasion. The results showed that tidal channel networks presented increasing growth and development over time, and their spatial structure evolved from simple to complex. The external isolated expansion of S. alterniflora played a dominant role during the initial invasion stage, and then they connected the discrete patches into the meadow through marginal expansion. Afterwards, tidal channel-driven expansion gradually increased and became the primary way during the late invasion stage, accounting for about 47.3%. Notably, tidal channel networks with higher drainage efficiency (shorter OPL, higher D and E) attained larger invasion areas. The longer the tidal channels and the more sinuous the channel structure, the greater the invasion potential by S. alterniflora. These findings highlight the importance of structural and functional properties of tidal channel networks in driving plant invasion landward, which should be incorporated into future control and management of invasive plants in coastal wetlands.

Study on spatio-temporal variation and hydrological connectivity of tidal creek evolution in Yancheng coastal wetlands.

The ecological changes have attracted extensive international attention at Jiangsu Yancheng coastal wetland on the west coast of the Pacific Ocean in recent decades. Tidal creek is an important channel for material exchange between sea and land and plays an important role in the connectivity of water in coastal wetlands. The tidal flats from Sheyang Port to Liangduo Estuary in Jiangsu Province were selected and divided into five sub-study areas using each port as a split point. Based on the remote sensing image data from 1987 to 2020, this study used seven parameters (grade, number, length, density, curvature, bifurcation ratio, and drainage efficiency) to analyze the spatio-temporal divergence patterns and hydrological connectivity of tidal creek network. The results showed that (1) the area of tidal flat was reduced from 1024.87 to 352.05 km2, the total length of the tidal creek was directly reduced from 1061.27 to 640.74 km, the average density increased from 1.00 to 1.82 km/km2, and the total number increased by 33% in 1987-2020, indicating the tidal creeks tended to be "short, fragmented, and parallelized." (2) The development degree of tidal creek networks showed a trend of gradually increasing from north to south, in which the γ index in areas II and V were closer to 1/3 of tree shape after 2002, indicating that the development of tidal creeks in these two areas was better. (3) The spatial heterogeneity of hydrological connectivity levels of tidal creeks in the study area was obvious, which gradually increased from north to south. In 2020, Area I was the lowest, and ICmin was 0.14, and Area V was the highest, and ICmax was 0.90. (4) Reclamation was the main factor leading to the shrinkage and degradation of tidal creeks, but it also increased tidal creek density and hydrological connectivity per unit area; the expansion of Spartina alterniflora had a certain influence on the development of tidal creeks. The results of this study are expected to provide data support for understanding and predicting the evolution of the morphological characteristics of tidal creeks under the influence of human and natural activities and provide scientific reference for the protection and restoration of hydrological connectivity in coastal wetlands.

Loss of tidal creek ecosystem vitality caused by tidal flat narrowing on the central Jiangsu coast, China.

Globally, tidal flats are increasingly narrowing due to continuous reclamation and sea level rise. Nonetheless, the impact of tidal flat narrowing (TFN) on tidal creek systems that play a crucial role in the formation and shaping of tidal flats is not well understood, despite a cognition that the tidal flat-creek system is integrated and coevolved. In this study, based on the quantification and mapping of tidal creek ecosystem vitality (TCEV), we detected the state evolution of tidal creek systems in response to TFN process on the central Jiangsu coast (CJC), China. The results showed that two thirds of the original tidal flat width was lost from 1984 to 2020, with a narrowing rate of 210.9 m/yr. The seaward movement of seawall lines and the landward movement of low tide lines contributed 82.5 % and 17.5 % to this serious TFN process, respectively. Across the study period, the overall TCEV lost 82.3 % with a substantial transformation from high level to low level. In terms of three dimensions of structural complexity, functional integrity and spatial occupancy, the tidal creek system of CJC has greatly deviated from the high-quality state in 1984, which was significantly associated with TFN. For a natural mature tidal flat, the loss of its initial width seems acceptable when <1/3, but unacceptable when >1/2, which are two important thresholds corresponding to the lower and higher loss of TCEV, respectively. It is worried that the CJC tidal flat-creek system would fall into a vicious circle of state evolution. Therefore, efforts should be made to control irrational reclamation and perform ecological restoration based on an insight into the relationship between TCEV and TFN.

Spatiotemporal Distribution of Asian Horseshoe Crab Eggs Are Highly Intermingled with Anthropogenic Structures in Northern Beibu Gulf, China.

Identification, protection and restoration of spawning habitats are vital for protecting the depleted species. Asian horseshoe crabs are ecologically important macroinvertebrates in coastal and estuarine ecosystems. However, their spawning habitat studies were limited to several reports in tropical regions, possibly due to the lack of modified survey methods, particularly in habitats with a lower density of spawning adults, and/or intermingled with anthropogenic structures. In this study, the year-round egg distribution and spawning habitat baselines of Carcinoscorpius rotundicauda and Tachypleus tridentatus were determined in the northern Beibu Gulf, China. Our findings demonstrated that the peak spawning occurred in June-July and ceased in November-January when the average water temperature dropped below 20 °C. Egg aggregations were found < 10 cm beneath the sediment surface with regular tidal inundation, regardless of seasonal changes, in the vicinity of natural and artificial structures with elevated, mildly sloping substratum within the high tide zones. The nests were characterized by medium-sized sediment grains (0.5-0.9 mm), high temperatures (31-34°C), low water contents (0.8%-0.9%), and total organic carbon contents (0.5%-0.7%), which might maximize the hatching success. The identified nesting beaches were close to nursery habitats for juveniles, and tidal creeks were present as the possible corridor connecting these two important habitats through the dominant mangrove forests. The findings provide valuable insights in the scope of spawning behavior and nest-site selection of Asian horseshoe crabs under a mixture of natural and artificial structures, which could benefit future management efforts for the exploited spawning populations.

Distribution, sources, and ecological risk assessment of polycyclic aromatic hydrocarbons (PAHs) in the tidal creek water of coastal tidal flats in the Yellow River Delta, China.

The concentrations, distribution, sources and ecological risk levels of polycyclic aromatic hydrocarbons (PAHs) in tidal creek water from coastal tidal flats of the Yellow River Delta were investigated. The concentrations of 16 PAHs ranged from 0.113 to 1.533, with a mean value of 0.496 ± 0.035 µg L-1, which indicated a moderate level of pollution. The main long-term sources of PAHs in the coastal tidal flats of the Yellow River Delta were petroleum combustion and petroleum pollution. The ecological risk assessment showed that the levels of PAHs in tidal creek water of the coastal tidal flats in the Yellow River Delta corresponded to medium to high ecological risk levels, and a high probability of potential ecological risk, posing harm to aquatic organisms. Among the 7 sampling sites, site 5, site 6, and site 7 were at high ecological risk, and the other sites were at moderate ecological risk. PAH pollution in the tidal creek water near the Yellow River Estuary and farther south, in the coastal tidal wetland of Laizhou Bay, deserves special attention, especially with respect to the prevention and control of benzo[a]pyrene (BaP) pollution in the water.

Parameterizing the Yellow River Delta tidal creek morphology using automated extraction from remote sensing images.

The tidal creek is an important part of the intertidal zone, which maintains the balance between depositional processes and a given hydrodynamic environment. Much can be inferred about the development and evolution of a tidal creek by examining its morphometry characteristics; this information can also provide scientific decision support for the development and utilization of coastal tidal flats. In this study, we propose a complete system of large-scale tidal creek morphometry characteristic extraction algorithms. This system improved the intelligence of the node classification and the accuracy of the grading, as well as mitigates the interference of island-shaped tidal creeks in the automatic iterative classification process. And this system solves the problem of low post-processing efficiency due to the existence of a large number of discontinuous tidal creek arcs, and greatly reduces the error in the calculation of morphology characteristics. After accuracy verification, using this algorithm, the classification accuracy of tidal creek nodes is 92.22%, and the order and flow direction information of nearly a thousand tidal creeks can be quickly and automatically defined, and the classification is error-free. The whole process is fully automatic, and it is better than previous algorithms in terms of efficiency and accuracy. It's greatly improved. After quantifying tidal creek morphometry characteristics such as the order, number, length, sinuosity ratio, bifurcation rate, and density, we identified the factors that affect the development of the tidal creek network with respect to its seawater intrusion and vegetation distribution. Our conclusions are as follows: (1) The order and number of the tidal creeks increase from north to south and from west to east. And the average length of the tidal creek increases with the order of the tidal creek. The sinuosity ratio of the tidal creek on the land side is greater than that on the sea side. The density of the order 4 tidal creek system is greater than other tidal creek systems. The differences in these characteristics are mainly related to vegetation distribution and seawater erosion. (2) Seawater erosion promotes rapid changes in the tidal creek sinuosity ratio, bifurcation rate, and density. However, due to the shrinkage of the tidal flat catchment area, the rate of change of the tidal creek morphology characteristics has slowed. However, excessive erosion has narrowed the tidal flat catchment area, resulting in a slowdown in the variation of tidal creek morphology characteristics. The changes in the morphology characteristics of the tidal creeks on the west side of the Old Yellow River Estuary are affected by seawater erosion, showing obvious stages: various morphology characteristics increased rapidly before 2016, and the growth rate slowed after 2016. (3) At present, due to the vegetation gathering on the northern and southern sides of the Yellow River estuary, most of the tidal creeks have achieved equilibrium. The bifurcation ratio of the tidal creek system at all orders showed an increasing trend, but the increasing rate slowed down, from large-scale bifurcation to local etching. Our algorithm represents a significant step forward in the high-precision quantitative detection of tidal creek morphology characteristics, and our results provide evaluable insight into the necessity of monitoring the status and evolution of tidal flats.

Assessing hydrodynamic effects of ecological restoration scenarios for a tidal-dominated wetland in Liaodong Bay (China).

Estuarine wetlands have experienced a variety of ecological and environmental problems caused by natural and anthropogenic factors. China has proposed a series of measures and made great efforts to control coastal degradation; however, decision makers still urgently need to know which measures to implement and how they will influence the estuarine environment and functions. This study used field observations, a hydrodynamic model, and statistical methods to investigate the effects of potential restoration scenarios on hydrodynamic conditions in the tidal-influenced estuarine wetland system, Liaodong Bay (China). Results reveal that the average total phosphorus, organic carbon, available phosphorus, pH, total nitrogen content, and moisture content in the soil and sediment environment were 0.04 ± 0.003%, 0.84 ± 0.25%, 16.3 ± 4.7 mg/kg, 8.3 ± 0.1, 0.07 ± 0.02%, and 44 ± 2%, respectively, exhibiting an overall trend of degradation. A series of restoration scenarios in regards to hydrodynamic regulation and tidal inputs were used to preserve the ecological value of the estuarine wetland. Model simulations indicate that the significant improvement of hydrodynamic fields (inundation depth and flow velocity) is more likely to occur when the tidal amplitudes reach around 2 m, while relatively weak responses can be observed when the tidal levels are lower than 1 m. Additionally, the construction of floodgates may play a key role in determining the tidal inputs and flowpaths across the wetland. The modifications in micro-topography of the wetland may play a complementary role in enhancing the connectivity condition via increased creek depth of 0.5 m and width up to around 20 m. This work represents a first attempt in exploring hydrodynamic effects of restoration scenarios for a tidal-dominated wetland. An improved understanding of the estuarine system also highlights that the design and implementation of wetland restoration projects should use more comprehensive measures to achieve long-term landscape management, connectivity planning, and ecological sustainability.

The size and distribution of tidal creeks affects salt marsh restoration.

Salt marshes are changeable and important ecosystems that currently face various threats, including global climate change and human activities. The influence of these factors can result in the degradation of salt marshes. Tidal creeks, which are an important source of nutrients and other substances for salt marsh vegetation, play an important role in the health of salt marshes. In this study, the morphological characteristics of tidal creeks and the characteristics of two typical plants, Suaeda glauca (SG) and Phragmites communis (PC), in the Yellow River Delta, China were investigated to determine the effect of tidal creeks on these plants. Aerial photography and field measurements of tidal creeks were carried out from May to July 2018 in the study area. At the same time, nine line-intercepts were set in the vertical direction of tidal creeks to investigate plants. The results showed that different grades of tidal creek exerted no significant influence on the growth of either S. glauca or P. communis. However, unlike grade, the size of a creek and the distance from it had marked effects on these plants. The cross-sectional area of a tidal creek had a significant positive impact on the density of S. glauca (r = 0.39, p = 0.02). For P. communis, the depth of a tidal creek had a strong correlation with this species' density (r = 0.51, p = 0.04) and height (r = 0.63, p = 0.01). Meanwhile, there was a negative relationship between the distance from tidal creeks and the height of S. glauca (r = -0.52, p = 0.02). Conversely, the height (r = 0 0.90, p = 0.00) and density (r = 0.62, p = 0.01) of P. communis were positively affected by its vertical distance from tidal creeks. We found that the subtidal zone near a tidal creek was more conducive to the recovery and growth of S. glauca, and that areas further away from a tidal creek, located in the intertidal and subtidal zones, were more conducive to the recovery and growth of P. communis. The parameters associated with tidal creeks in the subtidal zone (cross sectional area 4.55 m2, distance 0-10 m) were beneficial for the growth of S. glauca. For P. communis, relevant features in the intertidal and subtidal zones (depth 0.40-0.45 m, distance 20-60 m) are useful. Our results suggest that attention should be paid to the effects of size and distribution of tidal creeks during the process of salt marsh restoration. This work also provides practical guidance for the restoration of native salt marshes in China.

A mangrove creek restoration plan utilizing hydraulic modeling.

Despite the valuable ecosystem services provided by mangrove ecosystems they remain threatened around the globe. Urban development has been a primary cause for mangrove destruction and deterioration in south Florida USA for the last several decades. As a result, the restoration of mangrove forests has become an important topic of research. Using field sampling and remote-sensing we assessed the past and present hydrologic conditions of a mangrove creek and its connected mangrove forest and brackish marsh systems located on the coast of Naples Bay in southwest Florida. We concluded that the hydrology of these connected systems had been significantly altered from its natural state due to urban development. We propose here a mangrove creek restoration plan that would extend the existing creek channel 1.1 km inland through the adjacent mangrove forest and up to an adjacent brackish marsh. We then tested the hydrologic implications using a hydraulic model of the mangrove creek calibrated with tidal data from Naples Bay and water levels measured within the creek. The calibrated model was then used to simulate the resulting hydrology of our proposed restoration plan. Simulation results showed that the proposed creek extension would restore a twice-daily flooding regime to a majority of the adjacent mangrove forest and that there would still be minimal tidal influence on the brackish marsh area, keeping its salinity at an acceptable level. This study demonstrates the utility of combining field data and hydraulic modeling to aid in the design of mangrove restoration plans.

Origins and environmental mobility of antibiotic resistance genes, virulence factors and bacteria in a tidal creek's watershed.

AIMS: To compare bacterial compositions of watershed run-offs released by a human settlement and a forested area, and to evaluate their role as carriers of antibiotic resistance and virulence genes. METHODS AND RESULTS: Run-offs from a forested area and a small settlement in a tidal creek' s watershed were compared for bacterial composition and profiles of 16 tetracycline resistance (TRG), eight virulence (VG) and integrase1 and 2 genes. Integrase 1 gene was detected only once. No integrase 2 gene was observed. VGs were detected only in settlement's run-offs, and TRG incidence frequency there was twice as high as in the forest's run-offs. Gene incidences revealed a positive correspondence to the rainfall, and weak correlations to water parameters. Metagenomic, Principle Coordinates and Shannon analyses together revealed distinctive bacterial compositions of the forest's and settlement's run-offs. Passage of the latter through a salt marsh resulted in the elimination of TRGs and three-fold decrease in VG incidence, and their bacterial composition was shifted towards that of the tidal creek. CONCLUSIONS: The settlement was a major source of TRGs and VGs in the watershed, but these contaminants were mitigated by a salt marsh system. SIGNIFICANCE AND IMPACT OF THE STUDY: Our data revealed the role of small settlements in biological contamination of the coastal waters. They also indicated that salt marshes are capable of reducing not only chemical but also biological contamination of run-offs.

Hydrochemistry and phytoplankton composition of two tidal creeks in South-Western Nigeria

As in other countries, the effects of human stressors on coastal areas and waters in Nigeria are increasing, and management strategies are urgent. In order to assess this, studies on phytoplankton composition in relation to physico- chemical characteristic of two tidal creeks in Lagos were conducted for six months (October 2007 to March 2008). Variations in some of the physical and chemical parameters such as rainfall, temperature, salinity, nitrate-nitrogen, phosphate- phosphorus, sulphate, salinity, biological oxygen demand and chemical oxygen demand influenced the phytoplankton abundance. Three major divisions were recorded for the two creeks: Bacillariophyta, Chlorophyta and Cyanophyta. Among these, diatoms were the most abundant group observed. Water quality characteristics reflected the effect of tidal influence and consequent salt water inflow, fresh water incursion and the pollution status of one of the creeks, as a result of industrial and commercial activities in the area. Rev. Biol. Trop. 58 (3): 827-840. Epub 2010 September 01.

Como en otros países, los efectos de actividades antropogénicas en las zonas costeras y las aguas de Nigeria están aumentando, y las estrategias de gestión son urgentes. Durante seis meses (octubre 2007-marzo 2008) se estudió la composición del fitoplancton en relación con las características físico-químicas de dos canales en Lagos, Nigeria. Las variaciones en algunos de los parámetros físicos y químicos tales como precipitación, temperatura, salinidad, nitrato-nitrógeno, fosfato-fósforo, sulfato, salinidad, demanda biológica de oxígeno y demanda química de oxígeno; afectan la abundancia del fitoplancton. En los dos arroyos se registraron tres divisiones principales: Bacillariophyta, Chlorophyta y Cyanophyta, las diatomeas fueron el grupo más abundante observado. Características de calidad del agua reflejan el efecto de la influencia de las mareas y la consiguiente entrada de agua salada, la incursión de agua dulce y el estado de contaminación de uno de los canales, como consecuencia de actividades industriales y comerciales en la zona.

Evaluation of the water quality of tidal creeks of Pontal do Paraná, Paraná, Brazil

The aim of this wat was to evaluate the water quality in four tidal creeks of Paraná, Brazil, with different anthropic influences. Samples were collected every three months. Temperature, salinity, pH, alkalinity, total CO2, dissolved O2, nitrite, nitrate, N-ammoniacal, phosphate, silicate, particulate suspended matter, humic matter, total chlorophyll, total and fecal coliform bacteria of surface water were measured in each sample and compared. For all the stations water temperature was lower in winter, but ranged within typically subtropical values. Salinity (7 - 25) and pH (7.08 - 7.91) were higher in Perequê tidal creek indicating that only this tidal creek was strongly influenced by the nearby ocean waters. Lower dissolved O2, reaching anoxic levels along with higher phosphate and N-ammoniacal concentrations and higher total (<200 - 160,000 MPN 100 ml-1) and thermotolerant coliforms (<200 - 50,000 MPN 100 ml-1) in Olho d´Água suggested euthrophication, especially in summer when rainfall was higher and tourism was at its peak. Perequê, Penedo and Barranco Creeks were characterized as meso- and oligotrophic environments.

Foi objetivo da presente pesquisa, avaliar a qualidade da água de quatro gamboas do Paraná, Brasil, que sofrem influências antrópicas distintas. Em cinco coletas trimestrais, foram obtidas, as seguintes variáveis em águas superficiais: temperatura, salinidade, pH, alcalinidade, dióxido de carbono, oxigênio dissolvido, nitrito, nitrato, N-amoniacal, fosfato, silicato, material particulado em suspensão, substâncias húmicas, clorofila total, coliformes totais e coliformes termotolerantes. Os resultados mostraram que a temperatura da água apresentou características tipicamente subtropicais com valores significativamente menores no inverno em todas as estações. A salinidade (7 - 25‰) e o pH (7,08 - 7,91) mais elevados, registrados na Gamboa Perequê, indicaram que somente este curso d´água é influenciado pelo mar adjacente. As quantidades baixas de oxigênio dissolvido, chegando a anoxia, altas de fosfato (8,11 - 208,11 µM), N-amoniacal (0,90 - 75,33 µM), coliformes totais (<200 - 160.000 NMP 100 mL-1) e coliformes termotolerantes (<200 - 50.000 NMP 100 mL-1) observadas na Gamboa Olho d´Água indicam que esta apresenta características típicas de eutrofização, principalmente no verão, época de maior pluviosidade e maior fluxo de turistas na região. As gamboas Perequê, Penedo e Barranco podem ser caracterizadas como gamboas meso- e oligotróficas.

Dial organic carbon fluctuations in a mangrove tidal creek in Sepetiba bay, Southeast Brazil

The carbon (C) concentration and flux, as dissolved organic carbon (DOC), particulate organic carbon (POC) and macrodetritus (MD), were quantified through 4 tidal cycles in a mangrove tidal creek in Southeastern Brazil. DOC was the major fraction of the total C concentration, accounting for 68 and 61 percent of the total C concentration during ebb and flood periods respectively. Concentrations of DOC (Ebb = 3,41 ± 0,57 mgC.L-1 and Flood = 3,55 ± 0,76 mgC.L-1) and POC (Ebb = 1,73 ± 0,99 mgC.L-1 and Flood = 1,28 ± 0,45 mgC.L-1) were relatively similar during the four tidal cycles. Macrodetritus presented a wide variation with concentration peaks probably related to external forces, such as winds, which enrich the ebb flow with leaf litter. DOC and POC fluxes depended primarily on tidal and net water fluxes, whereas MD fluxes were not. The magnitude of the DOC and POC fluxes varied with the area flooded at high tide, but not the MD fluxes. DOC was the major form of carbon export to Sepetiba Bay. During the four tidal cycles, the forest exported a total of 1,2 kg of organic carbon per ha, mostly as DOC (60 percent), followed by POC (22 percent) and MD (18 percent).

As concentrações e fluxos de carbono orgânico sob forma de carbono orgânico dissolvido (COD), carbono orgânico particulado (COP) e macrodetritos (MD) foram quantificadas durante 4 ciclos de maré em canal de maré na Floresta Experimental de Itacuruçá, Baía de Sepetiba, RJ, litoral sudeste do Brasil. COD foi a fração mais importante para a concentração total de carbono orgânico, contribuindo com 68 e 61 por cento da concentração total de C nos períodos de maré vazante e enchente, respectivamente. As concentrações de COD (vazante = 3.41 ± 0.57 mgC.L-1 e enchente = 3.55 ± 0.76 mgC.L-1) e COP (vazante = 1.73 ± 0.99 mgC.L-1 e enchente = 1.28 ± 0.45 mgC.L-1) foram similares durante os 4 ciclos de maré. A fração macrodetritos apresentou uma ampla variabilidade com máximos de concentração relacionados a fatores externos como ventos, que enriqueceram as águas de vazante com macrodetritos. A magnitude dos fluxos de COD e COP, mas não os de macrodetritos, relacionaram-se com os fluxos de água e a conseqüente área inundada pela maré. A fração COD foi a mais importante forma de exportação de carbono orgânico pelo manguezal. Durante os 4 ciclos monitorados, a floresta exportou um total de 1.2 kg de carbono orgânico, 60 por cento sob forma de COD, seguido pelo COP (22 por cento) e pela fração macrodetritos (18 por cento).