Pichavaram Mangrove Ecosystem Research Articles

Evaluating the climate change–induced vulnerability of the Pichavaram mangrove ecosystem through a stakeholder-centric multiscale approach

Evaluating the climate change–induced vulnerability of the Pichavaram mangrove ecosystem through a stakeholder-centric multiscale approach

Bioaccumulation of Heavy Metals Pollutants in Pichavaram Mangrove Ecosystem, Southeast Coast of India

Studies on contaminant bioaccumulation in tropical mangrove ecosystems are very limited. An attempt has been made to assess sources of primary productivity and chemical bioaccumulation behavior in true and associated mangrove plants, water, and sediments from the Pichavaram Mangrove Ecosystem. The water, sediment, and plant materials were collected at 7 different locations and the samples were analyzed to determine the concentration of heavy metals using a flame atomic absorption spectrophotometer. The result reviles that the maximum lead concentrations of 5.48 ppm/g were accumulated in sediment samples collected from shrimp pond effluent and 4.26 ppm/l from water during post-monsoon. The maximum Zinc concentration of 12.34 ppm/g was observed in sediment samples collected from degraded mangrove forests during post-monsoon and 10.99 ppm/g was observed in sediment samples during the summer season. Higher heavy metals concentration was observed during spring and summer this may be due to increased biological activities, land runoff and rainfall during these seasons. The maximum Copper concentration 9.07 ppm/g was observed in sediment at degraded mangrove forest during post-monsoon and 8.16 ppm/g was observed in sediment during the summer season. Heavy metals concentrations in different parts of A. marina mangrove plants were analyzed. In leaf sample, Pb 5.44 ppm/g in shrimp pond effluent site, Cd 4.97 ppm/g in degraded site, Zn 4.43 ppm/g in degrading site, Cr 2.17 ppm/g in Freshwater zone at Vellar, Hg 1.68 ppm/g in shrimp pond effluent site, Cu 0.86 ppm/g in Freshwater zone at Upannar was recorded. In stem sample Pb 6.89 ppm/g and Zn 5.67 ppm/g in the degraded site, Cd 5.27 ppm/g in the natural site, Hg 4.91 ppm/g in degrading, Cr 2.49 ppm/g and Cu 0.87 ppm/g in Freshwater zone at Upannar was recorded. In Avicennia roots, Cr 10.89 ppm/g in shrimp pond effluent, Pb 10.17 ppm/g in natural site, Cd 6.89 ppm/g in freshwater zone at Vellar, Zn 6.86 ppm/g in degrading mangrove site, Hg 5.48 ppm/g in degraded site, Cu 0.92 ppm/g in backwater mouth was recorded. Heavy metals contamination was observed in almost all the samples in higher concentrations. The results indicate that Avicennia marina have a greater potential to observe and accumulate higher concentration than associated mangroves. A. marina plant can be used for phytoremediation to remove the heavy metals from the mangrove ecosystem and will help for ecological studies, conservation and sustainable management of the mangrove habitats.

Eddy Covariance Measurements of Carbon dioxide (CO2) Exchange in Pichavaram Mangrove Ecosystem, Southeast Coast of India

Net Ecosystem Productivity (NEP) and Net Ecosystem Exchange (NEE) of carbon dioxide (CO2) between the mangrove forest and the atmosphere were assessed during May 2016 to April 2017 in the Pichavaram mangrove ecosystem in India. An eddy covariance (EC) flux tower of about 10 m height was established in the middle portion of the mangrove forests to have a maximum carbon footprint from the mangroves. The EC tower was established to investigate whether the mangrove ecosystem acts as a sink or source of CO2. The monthly mean CO2 concentration varied from 376 ppm in July 2016 (during day time) to 466 ppm in December 2016 at night time. The EC based NEE showed a positive CO2 flux ranging from 4 μmol m-2s-1 in July 2016 to 6 μmol m-2s-1 in February 2017 during the night time. This was mainly due to respiration of the mangrove ecosystem. Negative CO2 flux values ranging from – 8 μmol m-2 s-1 (March 2017) to -18 μmol m-2 s-1 (August 2016) was observed during daytime, due to photosynthesis. The monthly analysis of the NEE during the daytime and night clearly indicate that the NEP of the Pichvaram mangrove was found to be positive throughout the study period suggesting that the Pichvaram mangrove ecosystem acts as a sink for CO2.The measured annual Net Ecosystem Productivity during the study period was 345 g Cm-2year-1, which is higher than the NEP reported for Sundraban mangroves (249 g C m-2 year-1). The total Gross Primary Productivity (GPP) and ecosystem respiration (Re) of the study area for the annual cycle was 2305 g C m-2 year-1and 1072 g C m-2 year-1, respectively. A long term study is needed to draw a logical conclusion on carbon sequestration potentials of this mangrove as well as to find out the role of environmental factors controlling CO2 fluxes.Keywords: Pichavaram Mangrove, Carbon dioxide, Eddy covariance, Net Ecosystem Productivity, Carbon sequestration

English

Mangrove crabs are mostly herbivorous which consume more amount of leaf litter of various mangrove species and also plays most important role in leaf degradation. Several studies reported that crab harbor bacteria from the environment through water and food. Bacterial species of the gut can influence the health and robustness of the host. The present study aims to isolate and enumerate the bacterial count from the gut of crabs collected from different mangrove environments.  The results shows that maximum bacterial load was recorded in Sesarma brockii crabs gut collected from Pichavaram mangroves and minimum was observed in Metopograpsus maculatus crabs collected from Uppanar estuarine mangrove. In the same way, maximum bacterial load was observed in both water and sediment samples of Pichavaram. Bacteria belonging to the genera Bacillus, Pseudomonas and Aeromonas were found at higher levels in all the different mangrove regions. In conclusion, crabs in the various mangrove environments carry a particular bacterial flora, which reflects their environment. The Pichavaram mangrove ecosystem is endowed with a high bacterial load due to the continuous shedding of foliage into the water and subsequent decomposition than other mangrove environments. SEM results confirm that crowded populations of bacteria were attached to the gut region of the mangrove crabs. Key words: Mangrove crabs, gut microflora, isolation, characterization, sediments.

Jeffries Matusita-Spectral Angle Mapper (JM-SAM) spectral matching for species level mapping at Bhitarkanika, Muthupet and Pichavaram mangroves

Abstract. This paper proposes a novel hyperspectral matching algorithm by integrating the stochastic Jeffries-Matusita measure (JM) and the deterministic Spectral Angle Mapper (SAM), to accurately map the species and the associated landcover types of the mangroves of east coast of India using hyperspectral satellite images. The JM-SAM algorithm signifies the combination of a qualitative distance measure (JM) and a quantitative angle measure (SAM). The spectral capabilities of both the measures are orthogonally projected using the tangent and sine functions to result in the combined algorithm. The developed JM-SAM algorithm is implemented to discriminate the mangrove species and the landcover classes of Pichavaram (Tamil Nadu), Muthupet (Tamil Nadu) and Bhitarkanika (Odisha) mangrove forests along the Eastern Indian coast using the Hyperion image dat asets that contain 242 bands. The developed algorithm is extended in a supervised framework for accurate classification of the Hyperion image. The pixel-level matching performance of the developed algorithm is assessed by the Relative Spectral Discriminatory Probability (RSDPB) and Relative Spectral Discriminatory Entropy (RSDE) measures. From the values of RSDPB and RSDE, it is inferred that hybrid JM-SAM matching measure results in improved discriminability of the mangrove species and the associated landcover types than the individual SAM and JM algorithms. This performance is reflected in the classification accuracies of species and landcover map of Pichavaram mangrove ecosystem. Thus, the JM-SAM (TAN) matching algorithm yielded an accuracy better than SAM and JM measures at an average difference of 13.49 %, 7.21 % respectively, followed by JM-SAM (SIN) at 12.06%, 5.78% respectively. Similarly, in the case of Muthupet, JM-SAM (TAN) yielded an increased accuracy than SAM and JM measures at an average difference of 12.5 %, 9.72 % respectively, followed by JM-SAM (SIN) at 8.34 %, 5.55% respectively. For Bhitarkanika, the combined JM-SAM (TAN) and (SIN) measures improved the performance of individual SAM by (16.1 %, 15%) and of JM by (10.3%, 9.2%) respectively.

The Coleroon river flow and its effect on the Pichavaram mangrove ecosystem

The fresh water reaching an estuary fluctuates on many scales and the fluctuation in the flow over a time period is also due to the anthropogenic activities like construction of dams, diversions and upstream withdrawals. These fluctuations may have profound effects on the estuarine ecosystem, which usually has remarkable biological productivity and diversity. A desktop analysis is carried out by compiling historical records of discharge and other hydrological information to study the dynamics of the river Coleroon, a distributary of the Cauvery River, Tamil Nadu, India. Remote sensing analysis was carried out on images ranging from the years 1977 to 2008 and the changes in the Pichavaram mangrove areas adjoining the Coleroon were studied by comparing the results with the freshwater flow into the ecosystem. Environmental flow analysis indicates that the minimum flow needed for a healthy mangrove system in Pichavaram is 750.75 cumecs; however, this is currently achieved only 12 % of the time. The reduction in freshwater flow over the years has resulted in loss of species diversity and degradation of the mangroves; this needs to be corrected immediately to conserve the Pichavaram mangrove ecosystem.

NUMERICAL SIMULATION OF TIDAL CIRCULATION IN THE PICHAVARAM MANGROVE ESTUARY

A vertically averaged numerical model is developed using the Surface water Modeling System (SMS) for t he Pichavaram Mangrove Estuary to study the tidal characteristics which en ables the simulation of the whole water circulation within the water body. The Pichavaram mangrove ecosystem is a complex network of creeks, mangroves and mud flats housed between t he Vellar and Coleroon rivers, 15 km north of Chidambaram, Tamil Nadu, Ind ia. A portion of the Coleroon river drains into the mangroves, and tidal flow is through the Coleroon mouth and a small inflow from an inlet in the north. The reduction of freshwater flow over the years has led to a degradation of the mangroves and changes in sedimen tation patterns. The results are calibrated against data collected previously. From the simulated results it is noticed that the tflow from the Coleroon mouth dominates the ent ire system. The maximum flood and ebb tide speed reached 0.777 ms -1 and 0.468 ms -1 during monsoon and post monsoon periods, respectiv ely. The tide showed a pronounced asymmetry in mangroves and a 12% increas e in total depth of water with a maximum increase i n water level of about 5 cm is noticed between monsoon and post monsoon cond itions. The dominance of ebb tide is noticed due to friction in the mangrove forest, which has resulted in slower flood current and greater tidal asymmetry in the waterway.

English

An attempt was made to study the benthic biodiversity in Pichavaram mangrove ecosystem, Southeast coast of India. Monthly (duplicate) sampling was done in 3 stations, (Station I - fresh water zone, Station II - core mangrove zone and Station III - marine zone) for a period of one year from January 2008 to December 2008. As many as 22 species of benthic macro fauna were recorded in the study area (16 species of polychaetes, 4 species of crustaceans and 2 species of molluscs). The population density varied between 394 and 23,888 number/m2. The species diversity was ranged from 1.52 to 3.87; species richness was from 1.24 to 4.09 and species evenness from 0.71 to 0.96. The maximum diversity was recorded in Station II and minimum in I. As observed in the conventional indices, the values of taxonomic and phylogenetic diversity were also more in Station II compared to Stations I and III. K- Dominance curve drawn paralleled the trend of diversity indices. Cluster and MDS showed the similarity in faunal composition stations within the zones. Key words: Mangroves, benthos, biodiversity, polychaetes.

Identification of hot spots and well managed areas of Pichavaram mangrove using Landsat TM and Resourcesat—1 LISS IV: an example of coastal resource conservation along Tamil Nadu Coast, India

The present work is a multi-temporal satellite based study on the spatial dynamic of an important coastal habitat, the Pichavaram mangrove ecosystem, over a period of 15 years. The Pichavaram mangrove forest near Chidambaram, South India is the second largest mangrove forest in the world. Unsupervised classification, the Iterative Self Organising Data Analysis Technique (ISODATA), has been used to classify the mangrove cover into the open and dense classes. The status of the classes has been monitored using Landsat TM of 1991, 2001, and Resourcesat–1 LISS IV of 2006 satellite data. The study demonstrated that by classifying mangrove ecosystem into just the 3 classes using remote sensing data and by studying their temporal variations, it is possible to get a reasonably accurate picture of the extent and condition of the mangrove ecosystem. The total area of the Pichavaram mangrove showed a net increase of 2.51 km2 within a span of 15 years (1991 to 2006). The hot spots that are at a risk of being degraded, and on the other hand, the mangrove areas that are well managed are identified using Geographical Information System (GIS) tools for the restoration and conservation measures.

Phosphorus fractionation in sediments of the Pichavaram mangrove ecosystem, south-eastern coast of India

Present study examined phosphorus dynamics through delineation of source as well as availability of phosphorus and its fractionation within the intertidal sediments of Pichavaram mangrove ecosystem. Twelve sediment samples and two cores were collected from the mangrove forest along with estuarine area (Vellar-Coleroon) during January 2005. Sediments were analyzed for total phosphorus and its fractionation using operationally defined chemical sequential extraction scheme (SEDEX). Dissolved phosphorus (in water) and total phosphorus (in sediments) concentrations were high in the Vellar region of Pichavaram mangrove area due to pollution load from nearby villages and agricultural fields. However, the spatial variation in dissolved phosphorus were insignificant (at significance level = 0.05). The results for the phosphorus fractionation (post-tsunami) were compared with earlier studies (pre-tsunami). It was observed that all phosphorus fractions (except adsorbed-phosphorus) showed a highly significant (at significance level = 0.05) increase in concentration after the tsunami event. There was significant decrease in the adsorbed phosphorus concentration as a result of tsunami. The changes were more pronounced for organic phosphorus which increased by almost twofold following the event. These variations were attributed to change in salinity, increase in dissolved oxygen as well as the retreat of tsunami water carrying the waste load. The vertical distribution of phosphorus through core sediments showed that mixing after tsunami had altered the different phosphorus fraction and its availability. Overall, the study indicated that the fluvial weathering along with litter degradation and anthropogenic sources controlled the biogeochemistry of phosphorus in this mangrove ecosystem. Observed changes in the concentrations are a result of altered physico-chemical characteristics caused by tsunami.

Bulk organic matter characteristics in the Pichavaram mangrove – estuarine complex, south-eastern India

The Pichavaram mangrove ecosystem is located between the Vellar and Coleroon Estuaries in south-eastern India. To document the spatial-depth-based variabilities in organic matter (OM) input and cycling, five sediment cores were collected. A comparative study was carried out of grain-size composition, pore water salinity, dissolved organic C (DOC), loss-on-ignition (LOI), elemental ratios (C/N and H/C), pigments (Chl a, Chl b, and total carotenoids), and humification indices. Sand is the major fraction in these cores ranging from 60% to 99% followed by silt and clay; cores from the estuarine margin have high sand content. In mangrove forests, pore-water DOC concentrations are high (32 +/- 14 mg L(-1)), whereas salinity levels are low (50 +/- 5.5 parts per thousand). Likewise, LOI, organic C and N, and pigment concentrations are high in mangroves. OM is mainly derived from upstream terrestrial matter and/or mangrove litter, and marine OM. The humification indices do not vary significantly with depth because of rapid OM turnover. The bulk parameters indicate that the Vellar and Coleroon Estuaries are more affected by anthropogenic processes than mangrove forests. Finally, greater variability and sometimes lack of specific trends in bulk parameters implies that the 2004 tsunami caused extensive mixing in sediments. (C) 2010 Elsevier Ltd. All rights reserved.

Assessment of metal enrichments in tsunamigenic sediments of Pichavaram mangroves, southeast coast of India

The 26 December 2004-Tsunami has deposited sediments in the Pichavaram mangrove ecosystem, east coast of India. Ten surface and three core sediment samples were collected within thirty days of the event. High concentrations of Cd, Cu, Cr, Pb, and Ni were observed in the tsunamigenic sediments. With respect to Fe, Zn, and Mn, there was little variation as compared to pre-tsunami values. The geo-accumulation index was calculated in order to assess the contamination of heavy metals in the sediments. The sediments were extremely contaminated with respect to Cd and they showed moderate to strong contamination with respect to Cr, Pb and Ni. The study highlighted the future risk of enhanced metal pollution in near future in this mangrove ecosystem.

Evaluation of geochemical impact of tsunami on Pichavaram mangrove ecosystem, southeast coast of India

The 26 December 2004-tsunami has deposited sediments in the Pichavaram mangrove ecosystem, east coast of India. Ten surface and three core sediment samples were collected within 30 days of the event and analyzed for nutrients. Water samples were also analyzed to see the impact of tsunami on the geochemical behavior of nutrients. An increase in the concentration of various nutrients namely nitrate and phosphate was observed. The geochemistry of the mangrove forest was observed to be influenced by a number of factors like rapid increase of aquaculture farms, agricultural practices and the anthropogenic discharge from the nearby-inhabited areas. Further the sediment column was disturbed due to energetic tsunami waves, which has caused a sheer increase in the dissolved oxygen in water. As a result, the change in the redox potential has resulted in change in the nutrients absorbed/associated with the sediments. In addition, role of retreating water after tsunami on the nutrient geochemistry was also evaluated.

Environmental geochemistry of the Pichavaram mangrove ecosystem (tropical), southeast coast of India

Spatial and temporal geochemical variations of various parameters in the water and sediment of a relatively small mangrove situated on the southeast coast of India were examined in detail for the first time. The water quality generally reflects the impact of seawater and the Vellar estuary (mixing effect) aided by evaporation and in situ biological productivity. The depletion and fluctuation of dissolved silica are controlled by biological processes. Nitrate and phosphate are contributed by fertilizer input from adjoining agriculture fields. Total suspended matter (TSM) shows an erratic range and trend due to deforestation and resuspension processes. Sand and silt constitute 70–90% of the sediments. Statistical analysis of the sediments shows the prevalence of a moderately high-energy environment with very effective winnowing activity. Organic matter content is higher in the mangrove sediments in comparison to adjacent estuaries. Water and sediment show fluctuations in their chemical concentration, but no specific trends could be identified. Heavy metals are also enriched in the mangrove sediments, indicating their unique chemical behavior and the existence of trapping mechanisms. Factor analysis and correlation analysis of water and sediments show the complexity of the system and the multitude of contributing sources. The core sediment chemistry suggests the depletion of metal input due to the damming of the detrital inputs. The Pichavaram mangrove seems to be relatively unpolluted, since the anthropogenic signal observed is small and acts as a sink for heavy metals contributed from a multitude of sources without an adverse effect.