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Anthropogenic influence on the physico-chemical parameters of Dhamra estuary and adjoining coastal water of the Bay of Bengal
Abstract
Estuaries receive the anthropogenic pollutants of their watershed area. Dhamra estuary, on the east coast of India, is such an estuary that receives a huge amount of pollutants, and it will eventually pose a threat to the ecological sensitive areas in its vicinity. Therefore, a study was carried out on physico-chemical parameters and chlorophyll-a to delineate the sources of variation during pre-monsoon and post-monsoon seasons. Surface water sampling was carried out from 12 stations in the estuarine and coastal area. Factor analysis and cluster analysis were applied to seasonal data to understand the sources of variation. From the study, it was observed that the chemical parameters are severely affected by anthropogenic influences such as sediment dredging, aquaculture effluent, and waste from industry and sewage from upstream. In the long run, this will affect the nearby nesting ground of vulnerable Olive Ridley turtles, high bio-diverse mangrove forests, and saltwater crocodile habitat.
... Various hydrodynamic factors such as wave, tide, wind action, altitude and latitudinal position, catchment area, and discharge, influence estuary's water quality. Seasonal variations have a profound impact on tropical monsoon-dominated estuaries of India, with the monsoon bringing large amounts of discharge, while pre-monsoon and post-monsoon periods experience lower flow towards the estuary (Swain et al., 2021). Understanding the impact of anthropogenic activities on physicochemical parameters during different seasons is important due to their immediate influence on the estuarine environment (Swain et al., 2021). ...
... Seasonal variations have a profound impact on tropical monsoon-dominated estuaries of India, with the monsoon bringing large amounts of discharge, while pre-monsoon and post-monsoon periods experience lower flow towards the estuary (Swain et al., 2021). Understanding the impact of anthropogenic activities on physicochemical parameters during different seasons is important due to their immediate influence on the estuarine environment (Swain et al., 2021). Therefore, systematic monitoring is essential to identify the key environmental indicator of the estuary through the analysis of physicochemical and biological parameters (Singh et al., 2022). ...
... Conversely, minimum DO levels during the pre-and post-monsoon seasons occurred due to reduced fresh water inflow and higher temperature (Balls et al., 1996). Similar observations were also recorded in Dhamra estuary and the neighbouring coastal water of the Bay of Bengal (Swain et al., 2021). The DO level in Gurupur stretch was comparatively lower (Fig. 2), possibly due to the volume of oxygen-depleting substances entering the estuary from surrounding industrial zones and sewage discharges. ...
The present study aimed to assess the water quality dynamics (physicochemical properties, nutrient and
chlorophyll–a) in the Netravathi-Gurupur estuary, India across the space and seasons and to simplify the complex
water quality dataset through a chemometric approach. The results indicated that pH, EC, temperature, alka�linity, salinity, TDS, hardness, chloride and intense mixing of suspended solids, driven by the semidiurnal tides,
are the major factors affecting water quality. Spatial heterogeneity and monsoon have profound impact on
nutrient distribution revealing the following values (mg l
− 1
): phosphate-P (0.015–0.105), nitrate-N
(0.016–0.094), nitrite-N (0.001–0.012), and silicate (1.83–14.50). The estuary was evaluated for suitability
for brackish water fisheries. The results indicated fair water quality during pre- and post-monsoon but marginal
quality in monsoon, primarily due to dilution associated with reduced salinity. The outcome of this study can be
suitably utilized for the sustainable development of estuaries and their feasibility for brackish water fisheries.
... The influence of currents and strong winds causes a more optimal mixing process in shallow waters, so that a more homogeneous water temperature is formed. Higher temperatures were also observed in the shallower waters of Dhamra Estuary, India due to the high solar insolation in summer (Swain et al., 2021). In general, the water temperature at each station is relatively high, this can also be caused by the intensity of the sun and strong wind speed. ...
... The existence of tidal and current conditions as well as strong winds at station 4, resulted in the sediment at the bottom being lifted back to the surface so that it had an impact on increasing the TSS value at that station. The sediment resuspension process becomes more optimal due to the shallow water depth at station 4. According to Swain et al. (2021), Tidal currents cause sediment resuspension from the bottom of the water, thus affecting the TSS value. While the low TSS value at station 1 is influenced by relatively calm current conditions, ...
... Station 2 is a water location with dense settlements, and piles of garbage along the river shoulder. According to Swain et al. (2021), the decrease in pH in the waters is influenced by organic matter that enters the system. Furthermore, Su et al. (2014) explained that organic matter that enters the system will be decomposed by microbes, Based on the Anova test on the pH value,there was a significant difference in pH for each station (p<0.05). ...
The coast is a water area that gets a lot of environmental pressure from human anthropogenic activities. As a result, many coastal areas are in a polluted condition, is no exception Bondet Estuary. An assessment of the condition and status of water quality needs to be carried out, as an effort to conserve coastal resources. This research aims to know the condition of water quality and determine the water quality status of the Bondet Estuary using the STORET method and the pollution index (IP). This study used survey method, where the determination of the sampling location is based on the purposive sampling method. Based on the STORET method, the water quality status of the Muara Sungai Bondet was moderately polluted with a score of -14 to -18, while the results of the assessment with the pollution index showed that it was lightly polluted with a value of 2.54 - 4.05. Several parameters that contribute to the condition of water quality degradation are salinity, TSS, and Pb. Based on these results, a sustainable management plan for the Bondet Estuary area is needed to reduce the negative impact on the environment due to various human activities.
... Due to the desorption and resuspend of heavy metals in the overlying water, variations in the hydrological circumstances (waves, wind), physico-chemical indicators (dissolved oxygen, pH, redox potential), and benthic bioturbation will result in secondary contamination [23]. When ingested in large quantities, metals are not metabolized by organisms and instead bioaccumulate in the soft tissues, causing cell structures damage, impeding the production of proteins and nucleic acids, and interfering with the processes of photosynthesis and energy transfer [2,6]. The main sources of trace and heavy metals are the anthropogenic activities (industry, agriculture, mining, aquaculture, household and urban activities). ...
... In its essentiality and simplicity, water supports biodiversity, aquatic biota and all terrestrial living creatures (biota and human life); water is the condition of life [1][2][3]. Worldwide, lakes cover a surface of around 100 km 2 (0.01 % of the global water resources, together with other bodies), including 1400 bodies (plus reservoirs), supporting over 100,000 species [4,5]. ...
Protected areas are significant due to the high value of natural resources they shelter. This study's primary objective is to assess the quality status of the water resources (13 lakes and Tisa River) localized in the protected area of Tisa River on the territory of Romania. A number of 13 lakes and surface water (Tisa River) situated in the protected area through the Natura 2000 ecological network are studied. The chemistry and potential pollution status were analyzed by measuring and analyzing a set of twenty elements and sixteen physico-chemical parameters. The potential impact of anthropogenic activities was settled through the applied analysis and obtained results. A potential human health risk was noticed. Results indicated that waters are rich in Ni and Fe probably due to interaction with groundwater rich in Fe and Ni. Waters are characterized by potential contamination, which if directly or through the food chain consumed could negatively influence the human health. Piper and Gibbs plots indicated that the studied waters are divided into three categories based on water-rock interactions: mixed Ca²⁺-Na⁺-HCO3⁻, CaCO3⁻, and Na⁺-HCO3⁻. Likewise, the applied pollution indices (Heavy metal Pollution Index, HPI and Heavy metal Evaluation Index, HEI) indicated three pollution categories correlated to the As, Ni and Fe amounts. The findings of this research imply that the chemistry of the studied lakes and surface waters is influenced by the geogenic origin and emergence of anthropogenic activities. The significance of this research is related to understanding of mechanisms that influence the water quality, improving and conserving the natural water resources, and correspondingly understanding if any potential human health risks could be identified.
... The majority of this extra carbon, roughly 0.4 Pg C year −1 , either returns to the atmosphere as carbon dioxide or is stored in sediments, approximately 0.5 Pg C year −1 , within freshwater environments, estuaries and coastal waters and around 0.1 Pg C year −1 of carbon reaches the open ocean. Due to the suitable climatic conditions and hydro-topography, aquaculture growth is rapidly enhancing in Dhamra (Swain et al. 2021). During aquaculture production, organic residues like uneaten feeds, phytoplankton and feces enter the adjacent water bodies (Herbeck et al. 2013;Chen et al. 2015), which might become the source of labile carbon and nitrogen to microbes that can stimulate microbial decomposition and consecutively emissions of CO 2 . ...
... Both pCO 2 (aq) and CO 2 efflux were significantly different in the monsoon season compared to the pre-monsoon and postmonsoon seasons. The seasonality observed for pCO 2 (aq) and efflux data in the present study is coherent with the previous observation of Pattanaik et al. (2019), Pattanaik et al. (2020a, b), and Swain et al. (2021) carried out in the Dhamra Estuary. Nevertheless, the adjacent estuaries like the Mahanadi Estuary, Devi Estuary, Godavari Estuary, and Matla Estuary showed different flux behavior being a source in monsoon with different intensities (Dey et al. 2013;Ganguly et al. 2011;Pattanaik et al. 2020, b;Akhtar et al. 2021;Sarma et al. 2011;Akhand et al. 2021a, b; Table 5). ...
Small estuaries often remain neglected while characterizing air-water CO2 flux dynamics. This study reports the seasonal, spatial, and multi-annual variability of carbon biogeochemistry, emphasizing air-water CO2 flux from a small tropical mangrove-dominated estuary (Dhamra Estuary) of the Bay of Bengal, based on the 9-year-long sampling survey (2013 to 2021). The sampling covered twelve pre-fixed locations of this estuary. A suite of biogeochemical parameters was kept within the purview of this study to deliniate the interrelationship between CO2 fluxes and potential factors that can regulate/govern pCO2(aq) dynamics. Air water CO2 exchange rates were calculated using five globally accepted empirical gas transfer velocity equations and varied in a range of − 832.5 to 7904 μmol m–2 h–1. The estuary was a sink for CO2 in monsoon season, having the highest average flux rates of − 380.9 ± 125.5 μmol m–2 h–1, whereas a source in pre-monsoon (38.29 ± 913.1 μmol m–2 h–1) and post-monsoon (91.81 ± 1009.8 μmol m–2 h–1). The significant factors governing pCO2 were pH, salinity, total alkalinity and dissolved inorganic carbon (DIC). This long-term seasonal study emphasizes the need to include small regional estuaries for more accurate estimates of global CO2 flux to upscale the global carbon budget and its controlling mechanism.
... Seasonality in a tropical country like India has a significant influence on the variation of physico-chemical parameters in the estuarine and coastal ecosystems (Sahu et al., 2016;Swain Table 2 and variation in different area are represented in Fig The pH of water affects the metabolism and other physiological process of aquatic ecosystem which exert considerable influence on toxicity of ammonia and hydrogen sulphide and affects the solubility of nutrient and fertility (Behera et al., 2017). The results did not vary significantly during the study period ranging from 7.8 to 8.5 (Table 2). ...
... The lowest salinity in monsoon may be due to influence of precipitation and massive inflow of fresh water into the estuary decreasing the salinity by diluting marine water whose impact lasts till post monsoon (Satpathy, 1996;Sampathkumar and Kannan, 1998;Muduli and Panda, 2010;Satpathy et al., 2018;Naik et al., 2020). The average salinity remained higher in the pre monsoon may be due to high evaporation to precipitation ratio as observed by Mishra et al. (2018) and Naik et al. (2020) from Paradeep coastal region and Swain et al. (2021) from Dhamra estuary. ...
... The intracellular influx of Mg and Ca content of soil facilitate ROS generation by increasing respiratory chain activity (Morais et al., 2017) that is neutralized by elevated CAT activity, which was noticed in tissue samples sampled during the summer season in Jagatsinghpur. However, the observed CAT activity in the Chandipur sampling site might be due to the presence of pollutants like organic xenobiotics (Swain et al., 2021). Additionally, low pH, i.e., below 6.5, reduces CAT activity as it loses stability at such pH level (Sánchez-Virosta et al., 2019), which was observed in HP tissue sampled during summer and rainy seasons from the Jagatsinghpur site. ...
... The observed GST activity in muscle tissue, irrespective of season and sampling site, could be due to a low accumulation of muscle xenobiotics compared to gill and HP tissues (Agah et al., 2008). The level of Mg, Ca, salinity, and temperature of water and soil samples collected from the Jagatsinghpur site might be responsible for the elevation of GST activity through Casensitive up-regulation of ABC transporter (Stewart et al., 2015), facilitating xenobiotics influx in crab HP tissues (Swain et al., 2021). However, apart from these suitable and sensitive stress markers, overall antioxidant capacity analysis of tissue will give more insight into the stress condition of carbs. ...
Studies on the synergetic effects of soil and water parameters on Oxidative Stress (OS) physiology systems of the edible mud crab Scylla serrata sampled from different parts of East India are unknown. This study aimed to evaluate the effects of soil Ca, Mg, and organic carbon load and water physicochemical stressors induced spatio-temporal variation of tissue-specific OS and antioxidant parameters in S. serrata along the Bay of Bengal in Odisha. Spectrophotometric or Fourier-transform infrared spectroscopy methods were employed to measure the OS physiology and physicochemical parameters. Pedological and physicochemical factors of water were varied significantly in summer (38–42°C), rainy (25–35°C), and winter (12–20°C) seasons. Activities of antioxidant enzymes (AE) such as superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), and the level of lipid peroxidation (LPx) were found to be higher in hepatopancreas as compared to other tissues irrespective of seasonal variation. Considering the impact of dry seasons, an average of 13.23% enhanced activities of AE were noticed in different tissues of S. serrata in response to temperature, salinity, organic carbon, Mg, and Ca load of sampling sites. However, about 11.26% decrease in the activities of AEs, including GR and GST in most of the tissues were recorded, along with a 21% alleviated level of LPx observed in the rainy season compared to other seasons. Among three coastal zones of the Bay of Bengal, the AEs in crabs sampled from Chandipur were elevated by 5.43% in winter, whereas a 7.05% enhanced level of LPx was found in summer compared to crabs sampled from Chilika and Jagatsinghpur. Overall, the levels of LPx, total antioxidant, and activities of AEs (CAT, GST, GPx, and GR) have shown a positive correlation, whereas ascorbic acid and GSH negatively correlate with habitat water pH, temperature, and salinity of soil and water. The results can be used for ecotoxic and environmental biomonitoring purposes using crabs as model organisms across tropical coastal regions.
... Jyotibandhu et al. (2003a) reported the abundant dinoflagellates community in the oceanic region of Bay of Bengal whereas in the present study less dinoflagellates (10 species) were recorded compared to Bacillariophycean species (Jyothibabu et al. 2003a). This may be due to environmental parameters such as light, temperature and salinity (Alkawri and Ramaiah 2010;Swain et al. 2021). ...
... This indication was responsible for the distribution of phytoplanktons between the sites and the variation of phytoplanktons between the sites in relation to physiochemical parameters. Present study suggested that the physiochemical parameters such as pH, temperature, salinity, conductivity, TDS and DO were strongly affected and play a vital role in the distribution of phytoplanktons between the sites of coastal Odisha (Maharana et al. 2019;Alkawri and Ramaiah 2010;Swain et al. 2021). Deceptively, our investigation suggested that the coastal Odisha is a dynamic variability ecosystem. ...
The eastern part of Odisha is the coastal line covering the districts from Ganjam to Balasore. In the present investigation, a total 54 phytoplankton species under 30 genera were reported from different sites of east coast Odisha. The diversity of phytoplankton included three divisions such as Chlorophyta (02 species), Bacillariophyta (42 species) and Dinophyta (10 species). Altogether 21 phytoplanktons were for the first time from the Odisha coast, namely Alexandrium foedum Balech, Bleakeleya notata (Grunow) Round, Coscinodiscus asteromphalus Ehrenberg, Coscinodiscus granii L.F.Gough, Coscinodiscus radiatus Ehrenberg, Coscinodiscus wailesii Gran & Angst, Diploneis vacillan var. renitens (A.W.F.Schmidt) Cleve, Diploneis littoralis (Donkin) Cleve, Ditylum brightwellii (T.West) Grunow, Gonyaulax polygramma F.Stein, Hemiaulus membranaceus Cleve, Lampriscus shadboltianum (Greville) Peragallo & Peragallo, Pediastrum duplex var. subgranulatum Raciborski, Pediastrum simplex Meyen, Proboscia alata (Brightwell) Sundström, Pseudonitzschia seriata (Cleve) H. Peragallo, Rhizosolenia pungens A. Cleve-Euler, Stephanopyxis palmeriana (Greville) Grunow, Thalassionema nitzschioides (Grunow) Mereschkowsky, Thalassiosira eccentrica (Ehrenberg) Cleve and Thalassiosira oestrupii var venrickae G.Fryxell & Hasle. Furthermore, our results revealed that few diatom species such as Coscinodiscus asteromphalus Ehrenberg, Coscinodiscus centralis Ehrenberg, Coscinodiscus radiatus Ehrenberg, Coscinodiscus wailesii Gran & Angst, Bacteriastrum delicatulum Cleve and Bacteriastrum hyalinum Lauder were recorded in more than five sites of east coast Odisha. By the analysis of Bary-Curtis similarity cluster, similarity index, Jaccard’s similarity and hierarchical cluster analysis showed that these species have the ability to survive in the diverse ecological conditions. On the other hand, only two species of chlorophyceae namely Pediastrum simplex Meyen and Pediastrum duplex var. subgranulatum Raciborski were recorded in two sites of Bhadrak district only. Moreover, 14 bloom and toxin producing phytoplanktons were for the first time recorded in the present study.
... As illustrated in Fig. 9b, the major industrial regions situated in these vulnerable zones contribute significantly to groundwater contamination. Industrial areas, particularly near Paradip and Dhamra ports, discharge substantial amounts of industrial runoff, compounding both the salinity and overall chemical load in the groundwater (Pati et al. 2023;Swain et al. 2021). This intensifies the existing pollution levels, further complicating water management efforts and exacerbating the degradation of groundwater quality in the region. ...
Groundwater is an essential freshwater source worldwide, but increasing pollution poses risks to its sustainability. This study applied a comprehensive approach to assess hydrogeochemical facies and groundwater quality in Odisha’s large low-lying coastal regions. Analysis of 136 samples revealed that sodium (9.4%), potassium (40.8%), bicarbonate (2.1%), and chloride (2.1%) exceeded WHO limits. The Groundwater Quality Index (GQI) map classified 5.1% of samples as “excellent,” 39.4% as “good,” 31.3% as “poor,” 13.8% as “very poor,” and 10.2% as “unsuitable” for use. Additionally, the GQI values demonstrate a random spatial autocorrelation (− 0.06) likely due to diverse influences. The study identified the expansion of agricultural (43%) and built-up areas (13%) from the Land Use/Land Cover (LULC) map. Piper diagram and Gibbs plots suggest continued freshening, rock-water interaction, and seawater intrusion. Groundwater levels fall between 0 to 2 m below ground level (mbgl), primarily due to excessive groundwater extraction. The Sodium (Na⁺) vs. Chloride (Cl⁻) cross plot shows most samples align with the mixing line, with some deviations indicating multiple contamination sources. The strong correlation (> 0.90) between total dissolved salts (TDS), electrical conductivity (EC), Na⁺, and Cl⁻ signals seawater intrusion, highlighting the complex interaction between human activities and natural processes. The proposed machine learning (ML) models like random forest (RF), artificial neural network (ANN), decision tree, and linear regression (LR) offer a reliable alternative to traditional GQI methods, addressing the challenges of extensive sampling and data management. Among these, RF exhibited the highest predictive accuracy (coefficient of correlation (R²) = 95%), surpassing ANN (R² = 82%), decision tree (R² = 81%), and LR (R² = 67%) as the most effective model for GQI prediction. Potassium (K⁺) stands out as a key indicator of contamination. GQI, LULC map, and ML methods improve understanding of contamination sources and support systematic groundwater management.
... The slight temperature variation reported in this study is consistent with the findings of Yan et al. 50 and Swain et al. 51 , who have noted that evaporation, precipitation, and human activities like dredging and industrial discharge can affect salinity levels. The salinity levels found in this research are within the range that is thought to be safe for aquatic life. ...
This comprehensive study delves into the Environmental Impact Assessment (EIA) and trace elements present in surface water, sediments, and fish within the riparian communities of the Niger Delta region, Nigeria. The study encompasses three key communities: Tema, Sangama, and Degema. Each community presents unique challenges, from illegal waste processing in Degema to residential waste overflow in Sangama and diverse activities in Tema. Sampling procedures were meticulously designed, considering characteristic features and pollution sites. The study assessed heavy metals such as zinc, lead, copper, cadmium, iron, and arsenic. Sample collection took place monthly from October 2021 to April 2022. Physicochemical parameters measured included pH, dissolved solids, dissolved oxygen, temperature, biological oxygen demand, salinity, and total conductivity. The results highlighted variations across stations, with Sangama exhibiting significantly different values in several parameters compared to Tema and Degema. The temporal analysis from October 2021 to March 2022 revealed fluctuations in physicochemical parameters, providing insights into the dynamic nature of the studied ecosystem. Heavy metal concentrations in sediment, water, and fish varied across stations, with Degema consistently showing the highest values. The results were compared against international standards, emphasising potential environmental concerns. Furthermore, the study explored spatiotemporal variations in heavy metal concentrations, uncovering patterns that contribute to a comprehensive understanding of the ecosystem dynamics. The findings from this study emphasize the critical need for sustainable environmental management practices in the Niger Delta. Informed decision-making is necessary to preserve the delicate balance of these riparian ecosystems based on the data generated.
... Sea level rise (SLR), altering ocean currents, increasing frequency of tropical cyclones, rising temperature, rainfall variability, and rising of CO 2 are all anticipated to have a significant impact on mangrove ecosystems (Ellison, 2015;Ward et al., 2016;McKee et al., 2012). There have been a number of studies on mangrove diversity (Kumar et al., 2013;Mishra et al., 2005;Pattanaik et al., 2008aPattanaik et al., , 2008bPradhan et al., 2016;Upadhyay & Mishra, 2008a, 2008bReddy et al., 2006;Panda et al., 2017); land use and land cover (Barik et al., 2016;Bhomia et al., 2016;Kumar et al., 2009;Kumar, 2015;Pattanaik, Sudhakar Reddy, et al., 2008); and environmental and societal impacts on mangrove of Bhitarkanika (Badola & Hussain, 2005;Banerjee et al., 2018;Behera et al., 2022;Bhomia et al., 2016;Das & Sandhu, 2014;Kadaverugu et al., 2021;Kumar et al., 2021;Palleyi et al., 2011;Swain et al., 2021;Banerjee et al., 2017;Mitra, 2019). Climate change impacts on the mangrove vegetation dynamics of Bhitarkanika is the first ever study and assumes importance for conservation and management of the Bhitarkanika mangrove ecosystem, the second largest mangrove forest of India. ...
... Alkalinity estimated the ability to neutralize acidic contamination in wastewater and the similar observation was reported by [35]. The alkalinity differs based on the changes in the pollutants [36]. ...
... In-situ observations of chlorophyll-a and total suspended matter for the study region were obtained from the studies of Pattanaik et al. (2020), Baliarsingh et al. (2021), Swain et al. (2021), wherein the protocols for extracting the water quality parameters were discussed in detailed by the authors. ...
Coastal water quality assessment is vital for monitoring the health of marine ecosystems. This work presents a comprehensive study on coastal water quality estimation along the Odisha coast, India, using Landsat-8 imagery. The study encompasses validation of retrieved parameters and the exploration of spatial and temporal variability. Using Landsat-8 data, we estimated key coastal water quality parameters viz. , chlorophyll- a concentration and total suspended matter. To ensure the accuracy of the retrieved parameters, we used in-situ data for validation. The validation results demonstrate a relatively high level of agreement between estimated and in-situ parameters, affirming the reliability of Landsat-8 data for coastal water quality assessment in this region. The retrieved concentration of total suspended matter and chlorophyll- a correlate well with the in-situ data (Pearson coefficient = 0.75 and 0.65, respectively). The 8-year averaged total suspended matter maps showed that highly turbid waters were primarily found around the Dhamra estuarine region, with a total suspended matter concentration greater than 50 g/m ³ . Moreover, our study revealed a significant spatial variability in water quality parameters along the Odisha coast. Additionally, the study highlighted the spatial and temporal variability of these parameters, providing valuable insights for coastal managements and environmental monitoring effects.
... Another process in N removal from the aquatic systems is the export to the coastal waters. It is well known that a considerable fraction of anthropogenic nutrient inputs gets transported to the adjacent coastal waters, and the biogeochemistry of coastal waters is closely linked to estuarine effluences (Paerl and Piehler, 2008;Bhavya et al., 2015Bhavya et al., , 2016aSwain et al., 2021). However, it remains challenging to determine the influence of terrestrial chemical loading on coastal ecosystems, especially tropical estuarine-coastal coupled systems, due to its complex physical and biogeochemical interactions (Cloern and Jassby, 2012). ...
The study assessed the Cochin estuary and adjacent coastal Arabian Sea for their seasonal variation in nitrate (NO3−) and ammonium (NH4+) uptake rates by total and nano + picoplankton using the 15N tracer technique. The results suggested that the NO3− and NH4+ uptake rates in the Cochin estuary are higher than those in the adjacent coastal Arabian Sea. NO3− and NH4+ uptake rates in the nearshore stations in the off Cochin station were high, indicating the influence of the eutrophic estuary. NO3− and NH4+ uptake rates conducted in off Mangalore transect were significantly lower than those of the off Cochin as it does not have an exchange with eutrophic systems. The nano + picoplankton's contribution to the total DIN uptake rates in the Cochin estuary was 77–98 %, indicating the relevance of nano + pico phytoplankton in the N cycling of the region.
... For example, global warming and the consequent flow of fresh water to the estuaries reduce the salinity of the mangrove habitats (Chilton et al. 2021). The increased water temperature and nutrient loading due to excess water inflow may lead to increased eutrophication and dissolved oxygen deficit resulting in hypoxic conditions (Swain et al. 2021). The increase in the sea level also increases the submergence of mangroves, which means mangroves may have to stay submerged and experience hypoxia for longer periods than they used to experience previously (Lovelock et al. 2017). ...
Mangroves inhabit coastal areas, estuaries and river mouths experiencing extreme abiotic stress conditions, which severely impact their growth and survival. They are constantly exposed to abiotic stresses such as salinity, drought, temperature, UV radiations, flood, and heavy metal toxicity, biotic stresses such as herbivory, pest infestation, and pathogenic attack, and anthropogenic disturbances such as land clearing, pollution and aquaculture. Though mangroves are well recognized as potent halophytes and stress-tolerant species, they also get disturbed by very high salinities and other stress extremities. To combat osmotic and oxidative stresses, mangroves exhibit many remarkable functional modifications such as ultrafiltration, salt secretion, altered xylem, modified wood anatomy and crown displacement. By differentially regulating antioxidant enzymes, transcription factors, metabolic pathways, and accumulating osmolytes/soluble sugars, mangroves survive to some extent under highly stressful conditions. In this review, we analyzed the existing evidence on the effects of osmotic (salinity, salinity-induced drought and freezing) and oxidative (flood and flood-induced anoxia and hypoxia) stresses on mangrove functional traits and their habitat adaptations. As plant functional traits are the characteristic determinants of plant-environmental interactions, this review discusses the dynamics of mangrove functional traits at the whole plant, morpho-anatomical, physiological, biochemical, reproductive and phenological levels. The proposed perspectives could be beneficial for gaining in-depth understanding of the effects of stresses on mangrove functional traits that are important for the conservation and management of mangroves.
... Both qualitative and quantitative assessment is essential for managing the estuarine ecosystem (Joseph and Ouseph 2009). Indian estuaries are inspected in a varied range of aspects with physico-chemical parameters as a key to understand; the ecology of Hooghly estuary (Basu et al. 2022;De et al. 2021;Mitra et al. 2018), the water quality of Rushikulya estuary (Naik et al. 2020), the nitrogen cycle in Mandovi estuary (Manjrekar et al. 2020), nutrients in Cochin estuary (Joseph and Ouseph 2009), anthropogenic influences in Dhamra estuary (Swain et al. 2021), pathogen contamination in Punnakayal estuary (Selvam et al. 2022). Ramanathan et al. (1993) have attempted to study the geochemistry of the Cauvery River Delta, and most of the studies are targeted at local scale, for example, Muthupet (Arumugam et al. 2016;Priya et al. 2016), Uppanar (Gopal et al. 2018;Karunagaran and Subramanian 1992), and Coleroon (Balakrishnan et al. 2015;Nethaji et al. 2017) estuaries. ...
Estuaries act as buffer/interface between fluvial and oceanic ecosystems and are highly sensitive to any changes in their physico-chemical and biological milieu. Understanding the nature, dynamics and periodic status of estuarine waters is of importance in the light of growing urban, industrial and recreational pressures, that ultimately culminate in the sustenance of human interests and health. In this study, we document a total of fourteen parameters including six in-situ (pH, DO, EC, TDS, salin-ity, temperature) and eight ex-situ (Na + , K + , Ca 2+ , Mg 2+ , HCO 3 − , Cl − , NO 3 − , SO 4 2− , F −) parameters in a tropical micro-tidal estuary of the Vettar River, one of the active and major tributaries of the Cauvery River draining Peninsular India. Twenty surface water samples from the estuarine head to confluence were collected and analyzed for determining the water quality and hydro-chemical processes with the help of established classification diagrams such as Schoeller plot, Gibbs diagram, Piper diagram, and computation of saturation index, besides the performance of statistical correlation and principal component analysis (PCA). These data were then plotted spatially in order to delineate zones of active pollution. For the assessment of pollution, the water quality index was incorporated. The results showed that the order of concentration (mg/l) of major cations (Na + > Ca 2+ > Mg 2+ > K +) and anions (Cl − > SO 4 2− >HCO 3 − >NO 3 − >F −) and Gibbs diagram shows the dominance of evaporation. Piper diagram demonstrated the dominance of Na + K > Ca + Mg and Cl + SO 4 2− > HCO 3 −. TDS, EC, and salinity displayed similar spatial variability; the rest all the other parameters showed irregular spatial distribution. Together, these results indicated the highly polluted nature of the waters and the unsuitable nature of the water for any purposes such as-domestic, industrial and irrigational.
... The observed activity of SOD in snails during the winter season was either due to deficiency in Mg content that induces ROS production or due to increase in mitochondrial membrane potential at low temperature (Kostov & Halacheva, 2018). The deposition of leftovers from anthropogenic activities may be the cause behind the observed changes in the activity of SOD (Swain et al. 2021) during all three seasons in muscle tissues of apple snails collected from Jagatsinghpur as compared to other sampling sites. ...
Information on the oxidative stress physiology parameters (OSPP) in general and as a function of the fluctuation of Mg, Ca and organic carbon present in soil and aquatic physico-chemical factors such as pH, temperature and salinity in particular are scanty in the amphibious snail Pila globosa. A spatio-temporal analysis of redox metabolism (as OSPP) followed by discriminant function analysis of the obtained data were performed in P. globosa sampled from the east-coasts of Odisha state, India (mostly along the Bay of Bengal) for environmental health assessment purposes. Results revealed that the OSPP are susceptible to seasonal synergistic variation of soil and physico-chemical factors. Overall, lipid peroxidation, total antioxidant capacity, activities of catalase, glutathione reductase had positive correlation whereas ascorbic acid, the reduced glutathione and the activity of superoxide dismutase had non-significant correlation with the soil Mg, Ca, organic carbon, and pH, temperature and salinity of water. In the summer season, the snails had a marked 51.83% and 26.41% higher lipid peroxidation level and total antioxidative activity as compared to the other seasons. Spatial variation of OSPP indicates that snails residing away from the Bay of Bengal coast had at least 4.4% lower antioxidant level in winter and 30% higher lipid peroxide levels in summer as compared to the rest of the sampling sites. Results on OSPP in P. globosa may be useful for monitoring the ecotoxic effects of environment using molluscs in general and P. globosa in particular.
... A low pH is given by the increase of CO 2 , HCO 3 and alkalinity of water, also caused by the presence of weak base salts in the spoil (Arulnangai et al., 2021;Mohammed et al., 2022). Swain et al. (2021) reported that low pH is also caused by low flow, richness in organic matter, remineralization of organic matter and degradation of vegetation. As the organic matter is decomposing, CO 2 is released and it reacts with water producing Table 1 Quality index parameters of the studied Ronișoara Forest (1-12). ...
This study was carried out in a protected area (Ronișoara Forest) in Romania. A combined approach of quality assessment of alluvial aquifers is employed, by determining the chemistry and applying two pollution indices based on heavy metals concentrations (HPI- Heavy metal Pollution Index and HEI- Heavy metal Evaluation Index), a quality assessment index based on specific physico-chemical indicators (WQI- the Water Quality Index) and different plots (Durov, Schoeller and TIS-Total Ion Salinity). The study revealed that waters are rich in manganese, calcium, sodium, sulphate, ammonium, manganese, iron, total dissolved solids, dominated by bicarbonates. The chemicals’ sources are related to the water–rock interactions and to mine exploitation activities. Correlations were observed between the electrical conductivity and sulphate, total dissolved solids and sulphate, and total hardness and electrical conductivity. The results based on the levels of heavy metals pollution indicate that the studied water samples are characterized by low, medium and high pollution levels, with values ranging between 0.40 and 234. The WQI scores vary from 8.6 to 54, generally indicating excellent and medium quality, and low quality for two samples. This research, one of the first in the area, can serve as a reference for the protection of natural water resources and for the contamination control of alluvial aquifers in the protected area of Ronișoara Forest.
... Pollution from anthropogenic waste can affect water quality, which is an important issue and needs immediate attention (Hegazy et al., 2020;Mahabeer and Tekere, 2021;Swain et al., 2021). Reliable information on the quality of coastal waters can be used to identify sources of pollution, determine the status of water quality, and control water pollution in the coastal water, in particular, runoff from land (Saraswati et al., 2019;Ustaoğlu et al., 2020;Wu et al., 2018). ...
The northern waters of Banda Aceh are connected with the Indian Ocean, the Andaman Sea, and the Malacca Strait, thus making the study of water quality parameters in this region is important for enviromental management. In this study, water quality parameters are measured spatially and then continued with assessing the pollution index. The results can be helpful for development planning and coastal pollution mitigation in Banda Aceh. The data was collected from 21 seawater samples from 11 stations representing the water of Banda Aceh on 10-11 September 2019. VanDorn bottles were used to store the seawater samples for laboratory analysis. Several parameters such as temperature, salinity, and pH were measured in situ, while other parameters were tested in the laboratory. Most heavy metal parameters showed values below the minimal and maximal value limit detection of the instrument, indicating a small potential for heavy metal contamination. However, the pollution index (PI) indicates the potential for water pollution dominated by nitrate and phosphate with a value that exceeds the water quality standard. The indications are shown from the high aquaculture and anthropogenic activities around the coast of Banda Aceh.
... Anthropogenic encroachment is not visible in the upper reaches of the Dhamra Estuary (i.e., Brahmani and Baitarini Rivers). Thus, the freshwater flow is well maintained in the Dhamra throughout the year (Swain et al., 2020). However, both of these estuaries connect to the Bay of Bengal, flow through dense mangrove forests, and share a similar and typical tropical climate (the mouths of these estuaries are only 120 km apart). ...
Reduction in riverine freshwater supply due to climate change as well as anthropogenic activities are documented throughout the globe. How river discontinuity in upstream reaches and the subsequent reduction in freshwater influx alter inorganic and organic carbon dynamics in downstream estuaries adjacent to mangroves has been rarely reported. We investigated the dynamics of the inorganic carbon system and organic matter (OM) in two Indian estuaries near mangroves; riverine freshwater supply to the Matla Estuary was reduced and that to the Dhamra Estuary was uninterrupted. Seasonal sampling was conducted over an annual cycle. We used elemental and stable isotope signatures to delineate the sources of OM and dissolved inorganic carbon (DIC). We found that compared to the Dhamra, the reduced riverine freshwater supply to the Matla increased the marine influence in the estuary on the OM degradation pathways and decreased CO2 emissions to the atmosphere. In the Dhamra, higher seasonal variability in biogeochemical pathways, facilitated high internal carbonate buffering capacity; in contrast in the Matla, the greater marine influence increased the carbonate buffering capacity, resulting in retention of higher DIC concentrations and low CO2 emissions. Dissolved and particulate organic carbon concentrations were higher in the Dhamra than the Matla, indicating higher riverine supply of these. The present study can contribute an overlooked effect of long‐term changes in riverine freshwater supply on the carbon dynamics of mangrove‐dominated estuaries, which might help to improve the understanding of coastal carbon budgets in a changing world.
Estuaries play a crucial role in preventing the influx of metals from rivers into seas, thereby offering potential
insights for the water purification industry. This study seeks to identify the key parameters (including pH,
electricity conductivity (EC), and Eh) influencing the removal efficiency of Mn, Zn, Cu, Co, and Ni during natural
and electro-flocculation processes in the Siahroud River estuary. The experiments were conducted in three
stages, each representing varying salinity levels and voltage conditions, to determine the most effective parameters
for metal removal. The findings revealed that heavy metal flocculation rates were highest at lower
salinities (0.5 to 1.5 PSU), with no significant improvement in contaminant removal observed with increasing
voltage. Electro-flocculation efficiency was found to be more dependent on Eh. Overall, the flocculation processes
reduced the annual total dissolved metal content from 14.84 to 6.46 tons, underscoring the potential of
this method in water quality management.
This study informs about seasonal influence on carbon stocks of data deficient saltmarsh from east coast of India
The sediments and surface water from 8 stations each from Dhamara and Paradeep estuarine areas were sampled for investigation of heavy metals, Cd, Cu, Pb, Mn, Ni, Zn, Fe, and Cr contamination. The objective of the sediment and surface water characterization is to find the existing spatial and temporal intercorrelation. The sediment accumulation index (Ised), enrichment index (IEn), ecological risk index (IEcR) and probability heavy metals (p-HMI) reveal the contamination status with Mn, Ni, Zn, Cr, and Cu showing permissible (0 ≤ Ised ≤ 1, IEn ˂ 2, IEcR ≤ 150) to moderate (1 ≤ Ised ≤ 2, 40 ≤ Rf ≤ 80) contamination. The p-HMI reflects the range from excellent (p-HMI = 14.89-14.54) to fair (p-HMI = 22.31-26.56) in off shore stations of the estuary. The spatial patterns of the heavy metals load index (IHMc) along the coast lines indicate that the pollution hotspots are progressively divulged to trace metals pollution over time. Heavy metal source analysis coupled with correlation analysis and principal component analysis (PCA) was used as a data reduction technique, which reveals that the heavy metal pollution in marine coastline might originate from redox reactions (FeMn coupling) and anthropogenic sources.
Crocodilians are a taxonomic group of large predators with important ecological and evolutionary benefits for ecosystem functioning in the face of global change. Anthropogenic actions affect negatively crocodilians’ survival and more than half of the species are threatened with extinction worldwide. Here, we map and explore three dimensions of crocodilian diversity on a global scale. To highlight the ecological importance of crocodilians, we correlate the spatial distribution of species with the ecosystem services of nutrient retention in the world. We calculate the effectiveness of global protected networks in safeguarding crocodilian species and provide three prioritization models for conservation planning. Our results show the main hotspots of ecological and evolutionary values are in southern North, Central and South America, west-central Africa, northeastern India, and southeastern Asia. African species have the highest correlation to nutrient retention patterns. Twenty-five percent of the world’s crocodilian species are not significantly represented in the existing protected area networks. The most alarming cases are reported in northeastern India, eastern China, and west-central Africa, which include threatened species with low or non-significant representation in the protected area networks. Our highest conservation prioritization model targets southern North America, east-central Central America, northern South America, west-central Africa, northeastern India, eastern China, southern Laos, Cambodia, and some points in southeastern Asia. Our research provides a global
prioritization scheme to protect multiple dimensions of crocodilian diversity for achieving effective conservation outcomes.
Pennar is one of the major rivers in south India and it has significant impact on water chemistry. This investigation intended to assess the water quality parameters of Pennar river estuary, Nellore, South East coast of India. A total of 20 bottom water samples were collected from chosen sample points during February 2020 and evaluated at fortnightly intervals to acquire baseline information on the estuarine water quality. Significant variations were observed in physicochemical parameters of water at different stations and these are as follows: pH (7.29–8.47), bottom water temperature (28.8–31.8 °C), air temperature (32.9–30.1 °C), EC (44.24–53.54 μmho/cm), Dissolved Oxygen (3.7–4.6 mg /l), Organic Matter (0.61–1.7 mg/l), Salinity (29.24–35.93 ppt), Nitrates (1.4–2.2 mg/l), and Sulphates (120–192 mg/l), respectively. Multiple statistical techniques such as Pearson Correlation Analysis, Factor Analysis (FA), and Hierarchical Cluster Analysis (HCA)were effectuated to the obtained datasets to determine the relationship among the selected parameters.KeywordsPennar river estuaryPhysicochemical parametersStatistical techniquesEast coast of India
Mangrove forest health is impacted by human-mediated activities in the Niger Delta such as industrial and coastal development activities (e.g., oil pipeline laying, construction, sand mining, and reclamation). These activities involve site preparation, which is the clearing of the trees with bulldozers, which emit pollutants into the atmosphere and discharge spent fuel into the swamp. Similarly, pollution from microindustries (e.g., block-making industry, food industries) situated near urban areas negatively impact the remaining forest by killing their leaves and roots. This chapter outlines some color combinations of leaves to demonstrate a visual health status of mangrove trees such as yellow, white, black, and gray, which indicate poor health caused by pollution and disease while green color indicates healthy trees. However, the observation was made by sight alone and does not probe further the internal state of the trees. This work recommends that buffer zones be created to protect urban mangrove forest from being exploited by land developers. In addition, anthropogenic activities that negatively impact the environment should be stopped to create a clean environment for the mangroves devoid of pollutants
Polycyclic aromatic hydrocarbons (PAHs) are examples of ocean garbage. These compounds have a long half-life, bio accumulate in the environment, harm marine flora and fauna. Seaweeds are currently attracting a lot of attention from scientists due to the bioactive chemicals they produce. A variety of seaweed products have unique nutraceutical, pharmacological, and biological qualities. As a result, the current analysis focuses on the state of organic pollutants in the marine environment, their consequences, and the numerous substances found in seaweed, as well as their applications and Nutraceutical properties.
Surface water partial pressure of carbon dioxide [pCO2 (water)], total alkalinity (TA), dissolved inorganic carbon (DIC), and air–water CO2 flux were measured in two estuaries of the Bay of Bengal namely Mahanadi and Dhamra. Though the annual average air–water CO2 fluxes at the Mahanadi and the Dhamra Estuaries were − 3.9 ± 21.4 (mean ± standard deviation) µmol m⁻² h⁻¹ and − 2.9 ± 11.6 µmol m⁻² h⁻¹, respectively, the intra-annual variation of air–water CO2 fluxes in the two estuaries was contrasting. Nonetheless, from the perspective of net primary productivity, the surface water of both the estuaries were found autotrophic throughout the study period with varying rates at different seasons and highest during summer months. Mahanadi Estuary acted as a CO2 source toward atmosphere during monsoon months, whereas, Dhamra Estuary acted as a source during pre-monsoon months. On the contrary, Mahanadi and Dhamra Estuaries acted as CO2 sink during pre-monsoon months and monsoon months, respectively. The salinity in Mahanadi Estuary was much lower compared to Dhamra, which indicated significant freshwater discharge rich in organic carbon, and the remineralization of this carbon to DIC during summer and monsoon months explained the CO2 source character. Whereas, in Dhamra, reduced freshwater flow and high turbidity were held accountable for net heterotrophic character of the water column during the post-monsoon months. The annual data set of air–water CO2 fluxes from these two estuaries produced from this study could be utilized in future to fill the data gap and upscale the Indian estuaries scenario from the perspective of blue carbon budgeting.
Short-term variability in physico-chemical properties of Dhamra estuarine system located in north-eastern India was investigated to understand the inter-seasonal variability. The oxygen data show 89–92% saturation in winter months compared to 60–70% during summer. Overall, the nitrate ranged between < 1.0 and 22.0 µmol l⁻¹; however, phosphate concentrations never exceeded 1 µmol l⁻¹ during the whole study period. In general, the lowest nutrient values were recorded during March and December irrespective of the year sampled. Pearson correlation matrix shows poor relationships between inorganic nitrate and phosphate suggesting decoupling in the Dhamra estuary. However, relationship between surface chlorophyll and nitrate was significant highlighting modest control on phytoplankton population. Interestingly, pCO2(air) exhibited considerable monthly variability during the sampling period, thereby accentuating the sea–air CO2 gradient. The pCO2(air) varied between 370 and 421 µatm, whereas pCO2(water) ranged between 146 and 751 µatm. The ΔpCO2 therefore showed monthly fluctuation and acted as a weak to moderate source to the immediate atmosphere. Our observation from Dhamra estuary suggests large inter-annual variability which therefore necessitates the need for near real-time measurements which is now a possibility with emerging coastal biogeochemical buoys.
Present investigation deals with the study of impact of dredging on water quality of Dhamra estuary, by evaluating the samples collected bimonthly from various sampling stations during April-2008 to March-2010. Study revealed that the dredging operation has drastic impact on water quality of Dhamra, as total suspended solid and turbidity of both surface and bottom waters are high at dredging channel. Similarly, higher concentration of nutrients in dredging channel and disposal site shows clear impact of dredging. However, in certain points higher dissolved oxygen were observed in surface water at dredging channel may be due to higher phytoplankton production. But Biochemical Oxygen Demand of both surface and bottom water was intensely influenced by dredging due to release of organic rich sediment.
Estuaries are biogeochemical hot spots because they receive large inputs of
nutrients and organic carbon from land and oceans to support high rates of
metabolism and primary production. We synthesize published rates of annual
phytoplankton primary production (APPP) in marine ecosystems influenced by
connectivity to land – estuaries, bays, lagoons, fjords and inland seas.
Review of the scientific literature produced a compilation of 1148 values of
APPP derived from monthly incubation assays to measure carbon assimilation or
oxygen production. The median value of median APPP measurements in 131
ecosystems is 185 and the mean is 252 g C m−2 yr−1, but the
range is large: from −105 (net pelagic production in the Scheldt Estuary)
to 1890 g C m−2 yr−1 (net phytoplankton production in Tamagawa
Estuary). APPP varies up to 10-fold within ecosystems and 5-fold from year to
year (but we only found eight APPP series longer than a decade so our
knowledge of decadal-scale variability is limited). We use studies of
individual places to build a conceptual model that integrates the mechanisms
generating this large variability: nutrient supply, light limitation by
turbidity, grazing by consumers, and physical processes (river inflow, ocean
exchange, and inputs of heat, light and wind energy). We consider method as
another source of variability because the compilation includes values derived
from widely differing protocols. A simulation model shows that different
methods reported in the literature can yield up to 3-fold variability
depending on incubation protocols and methods for integrating measured rates
over time and depth.
Although attempts have been made to upscale measures of estuarine-coastal
APPP, the empirical record is inadequate for yielding reliable global
estimates. The record is deficient in three ways. First, it is highly biased
by the large number of measurements made in northern Europe (particularly the
Baltic region) and North America. Of the 1148 reported values of APPP, 958
come from sites between 30 and 60° N; we found only 36
for sites south of 20° N. Second, of the 131 ecosystems where APPP
has been reported, 37% are based on measurements at only one location
during 1 year. The accuracy of these values is unknown but probably low,
given the large interannual and spatial variability within ecosystems.
Finally, global assessments are confounded by measurements that are not
intercomparable because they were made with different methods.
Phytoplankton primary production along the continental margins is tightly
linked to variability of water quality, biogeochemical processes including
ocean–atmosphere CO2 exchange, and production at higher trophic levels
including species we harvest as food. The empirical record has deficiencies
that preclude reliable global assessment of this key Earth system process. We
face two grand challenges to resolve these deficiencies: (1) organize and
fund an international effort to use a common method and measure APPP
regularly across a network of coastal sites that are globally representative
and sustained over time, and (2) integrate data into a unifying model to
explain the wide range of variability across ecosystems and to project
responses of APPP to regional manifestations of global change as it continues
to unfold.
Abundance and composition of
microzooplankton in Chilika Lake were studied covering
three seasons during 2012–2013. Ciliates (19 species),
rotifers (13 species), crustacean larvae (2 taxa) and
heterotrophic dinoflagellates (2 species) were the four
major groups. Ciliates, however, have emerged as the
most dominant group throughout the lake in all the
seasons except in the freshwater-influenced areas. The
average contribution of ciliates was highest (avg. 55.3
± 38.7 %) during the premonsoon season followed by
post-monsoon (avg. 49.0± 32.5 %) and monsoon (avg.
47.8± 41.6 %) seasons. Crustacean larvae formed the
second dominant group whose percentage contribution
was marginally high in the premonsoon (avg. 41.2
± 38.8 %) followed by monsoon (avg. 29.1± 27.0 %)
and post-monsoon (avg. 28.7 ± 23.4%). Results of cluster
analysis and multidimensional scaling on abundance
of microzooplankton depicted well-defined clusters.
The stations with high salinity formed a different group
indicating seasonal variation in species composition and
abundance of microzooplankton is primarily governed
by salinity.
Coastal erosion is one of the major problems of the coastal zone. The erosion is triggered by various reasons such as high wave energy, reduction of sediments, natural disasters and climate change etc. In the era of industrialization, major infrastructure developments are happening along the coast. Prior to the initiation of those projects, it is important to understand the coastal processes of erosion, deposition, sediment-transport, flooding and sea-level-changes of the region which continuously alters the shoreline. These processes disturb the stability and productivity of aquatic environment and may have severe implications for proprietors. This study attempts morphological assessment of shoreline in the middle coastal plains of Odisha state on the east coast of India. Shorelines changes study is carried out at Dhamra and Maipura Coast to quantify erosion and accretion during years 1990 – 2012. Satellite derived remote sensing data of LANDSAT and IRS P6 for the years 1990, 2000 and 2012 were used in this study. Dhamra coast has been modified in between these years due to anthropogenic disturbance such as port development. Maipura coast which has large mangrove cover, Bhitarkanika national park carries its ecological importance. These coasts experienced erosion during 2000-2012 compared to 1990-2000. Accretion is noticed in the nearby river mouths. Temporal variation of sediments and frequent flood events will also be discussed in the paper. The detailed analysis reveals that the maximum erosion of 227 m, 47 m in a decade at Dhamra and Maipura coasts respectively. Area of Dhamra coast was under accretion during 1990-2000 and this area experienced erosion near Dhamra port just after the development of port in 2007. This study concludes that shoreline of study area is under high risk of erosion and inundation due to natural as well as anthropogenic activities in the area.
Marine dredging is an excavation activity carried out worldwide by many industries. Concern about the impact dredging has on marine life, including marine mammals (cetaceans, pinnipeds, and sirenians) exists, but effects are largely unknown. Through consulting available literature, this review aims to expand on existing knowledge of the direct and indirect, negative and positive impacts on marine mammals. In terms of direct effects, collisions are possible, but unlikely, given the slow speed of dredgers. Noise emitted is broadband, with most energy below 1 kHz and unlikely to cause damage to marine mammal auditory systems, but masking and behavioural changes are possible. Sediment plumes are generally localized, and marine mammals reside often in turbid waters, so significant impacts from turbidity are improbable. Entrainment, habitat degradation, noise, contaminant remobilization, suspended sediments, and sedimentation can affect benthic, epibenthic, and infaunal communities, which may impact marine mammals indirectly through changes to prey. Eggs and larvae are at highest risk from entrainment, so dredging in spawning areas can be detrimental, but effects are minimized through the use of environmental windows. Sensitive environments such as seagrass beds are at risk from smothering, removal, or damage, but careful planning can reduce degradation. Assessing impacts of contaminant remobilization is difficult, but as long as contaminated sediments are disposed of correctly, remobilization is limited in space and time. Effects of suspended sediments and sedimentation are species-specific, but invertebrates, eggs, and larvae are most vulnerable. Positive effects, including an increase in food, result from greater nutrient loads, but are often short term. Dredging has the potential to impact marine mammals, but effects are species and location-specific, varying also with dredging equipment type. In general, evidence suggests that if management procedures are implemented, effects are most likely to be masking and short-term behavioural alterations and changes to prey availability.
Estuaries are biogeochemical hot spots because they receive large inputs
of nutrients and organic carbon from land and oceans to support high
rates of metabolism and primary production. We synthesize published
rates of annual phytoplankton primary production (APPP) in marine
ecosystems influenced by connectivity to land - estuaries, bays,
lagoons, fjords and inland seas. Review of the scientific literature
produced a compilation of 1148 values of APPP derived from monthly
incubation assays to measure carbon assimilation or oxygen production.
The median value of median APPP measurements in 131 ecosystems is 185
and the mean is 252 g C m-2 yr-1, but the range is
large: from -105 (net pelagic production in the Scheldt Estuary) to 1890
g C m-2 yr-1 (net phytoplankton production in
Tamagawa Estuary). APPP varies up to 10-fold within ecosystems and
5-fold from year-to-year (but we only found 8 APPP series longer than a
decade so our knowledge of decadal-scale variability is limited). We use
studies of individual places to build a conceptual model that integrates
the mechanisms generating this large variability: nutrient supply, light
limitation by turbidity, grazing by consumers, and physical processes
(river inflow, ocean exchange, and inputs of heat, light and wind
energy). We consider method as another source of variability because the
compilation includes values derived from widely differing protocols. A
simulation model shows that different methods can yield up to 3-fold
variability depending on incubation protocols and methods for
integrating measured rates over time and depth. Although
attempts have been made to upscale measures of estuarine-coastal APPP,
the empirical record is inadequate for yielding reliable global
estimates. The record is deficient in three ways. First, it is highly
biased by the large number of measurements made in northern Europe
(particularly the Baltic region) and North America. Of the 1148 reported
values of APPP, 958 come from sites between 30° N and 60° N; we
found only 36 for sites south of 20° N. Second, of the 131
ecosystems where APPP has been reported, 37% are based on measurements
at only one location during one year. The accuracy of these values is
unknown but probably low, given the large inter-annual and spatial
variability within ecosystems. Finally, global assessments are
confounded by measurements that are not intercomparable because they
were made with a broad range of methods. Phytoplankton
primary production along the continental margins is tightly linked to
variability of water quality, biogeochemical processes including
ocean-atmosphere CO2 exchange, and production at higher
trophic levels including species we harvest as food. The empirical
record has deficiencies that preclude reliable global assessment of this
key Earth-system process. We face two grand challenges to resolve these
deficiencies: (1) organize and fund an international effort to use a
common method and measure APPP regularly across a network of coastal
sites that are globally representative and sustained over time, and (2)
integrate data into a unifying model to explain the wide range of
variability across ecosystems and to project responses of APPP to
regional manifestations of global change as it continues to unfold.
Spatial and temporal variations in pelagic carbon fluxes were examined by means of a large-scale and long-term monitoring data set from the Kattegat, a shallow marginal sea impacted by man-induced eutrophication. Flows of carbon, nitrogen and phosphorus in the upper mixed layer (0 to 10 m) were estimated from a simple descriptive model using measurements of primary production, temperature, and phytoplankton/zooplankton biomass as input variables. For all years combined, annual primary production at coastal stations (171 g C m(-2) yr(-1); 8 stations) was almost twice that at the deeper open-water stations (105 g C m(-2) yr 1; 5 stations), which resulted in an annual primary production of 116 g C m(-2) yr(-1) for the region as a whole during the entire study period (1989 to 1997). Interannual variation in primary production was substantially smaller than the between-station variation. The phytoplankton spring bloom contributed substantially to annual production (10 to 20 %), but the magnitude and timing were highly variable between years. Respiration accounted for on average 12 % of the measured primary production. Annual sedimentation was estimated at 55 g C m(-2) yr(-1), equivalent to 54 % of net primary production. The estimated new production was significantly related to nitrogen loading from the land and atmosphere, and a regression analysis predicted declines of between 20 and 47 % in annual net primary production from a 50 % reduction in nitrogen loading. Carbon and nutrient fluxes are consistent with those of earlier studies from the Kattegat based on small-scale and short-term data sets. However, combining monitoring data with a budget model greatly improved data resolution in both time and space. Estimated C/N/P fluxes from the model can act as reliable indicators for assessing the state of eutrophication in the Kattegat and other inland seas impacted by man-induced nutrient loading.
In the present study, concentration of some selected trace metals (Fe, Mn, Ni, Co, Pb, Zn, Cu, Cr and Cd) are measured in Brahmani, Baitarani river complex along with Dhamara estuary and its near shore. Chemical partitioning has been made to establish association of metals into different geochemical phases. The exchangeable fraction is having high environmental risk among non-lithogeneous phases due to greater potential for mobility into pore water. The metals with highest bio-availability being Cd, Zn and Cr. The metals like Mn, Zn, Cd and Cu represent an appreciable portion in carbonate phase. Fe-Mn oxides act as efficient scavenger for most of the metals playing a prime role in controlling their fate and transport. Among non-lithogeneous phases apart from reducible, Cr showed a significant enrichment in organic phase. Risk assessment code values indicate that all metals except Fe fall under medium-risk zone. In estuarine zone Cd, Zn, Pb and Cr are released to 32.43, 26.10, 21.81 and 20 %, respectively, indicating their significant bio-availability pose high ecological risk. A quantitative approach has been made through the use of different risk indices like enrichment factor, geo-accumulation index and pollution load index. Factor analysis indicates that in riverine zone, Fe-Mn oxides/hydroxides seem to play an important role in scavenging metals, in estuarine zone, organic precipitation and adsorption to the fine silt and clay particles while in coastal zone, co-precipitation with Fe could be the mechanism for the same. Canonical discriminant function indicates that it is highly successful in discriminating the groups as predicted.
Historically, lake and reservoir management has focused on controlling external nutrient loading. However, it is becoming increasingly clear that internal mechanisms, such as the episodic resuspension of benthic sediments, can also contribute to the processes of eutrophication. We conducted laboratory bioassay experiments to determine how resuspended sediments affected nutrient concentrations and algal biomass in four eutrophic reservoirs of the Central Plains. Surficial sediments and surface water were collected from each reservoir and returned to the laboratory where they were added to 1-L bioassay bottles at five turbidity concentrations (0, 50, 150, 250, and 500 NTUs). Sediments in the bioassay bottles were resuspended daily, and algal biomass (measured as relative fluorescence) was measured for 11–14 days. Resuspended sediments at the lowest experimental turbidity concentration, 50 NTUs, had highly significant effects on algal biomass in each of the sediment resuspension bioassays. Algal biomass appeared to increase following experimental sediment resuspension due to an increase in available nutrients and/or the establishment of algae (meroplankton) from the sediment. Overall, our results highlight the importance of considering internal mechanisms when developing reservoir management and restoration plans for these important ecosystems.
This review provides an integrated synthesis with timelines and evaluations of ecological responses to eutrophi-cation in Chesapeake Bay, the largest estuary in the USA. Analyses of dated sediment cores reveal initial evidence of organic enrichment in ~200 yr old strata, while signs of increased phytoplankton and decreased water clarity first appeared ~100 yr ago. Severe, recurring deep-water hypoxia and loss of diverse submersed vascular plants were first evident in the 1950s and 1960s, respectively. The degradation of these benthic habitats has contributed to declines in benthic macro-infauna in deep mesohaline regions of the Bay and blue crabs in shallow polyhaline areas. In contrast, copepods, which are heavily consumed in pelagic food chains, are relatively un-affected by nutrient-induced changes in phytoplankton. Intense mortality associated with fisheries and disease have caused a dramatic decline in eastern oyster stocks and associated Bay water filtration, which may have exacerbated eutrophication effects on phytoplankton and water clarity. Extensive tidal marshes, which have served as effective nutrient buffers along the Bay margins, are now being lost with rising sea level. Although the Bay's overall fisheries production has probably not been affected by eutrophication, decreases in the relative contribution of demersal fish and in the efficiency with which primary production is transferred to harvest suggest funda-mental shifts in trophic and habitat structures. Bay ecosystem responses to changes in nutrient loading are complicated by non-linear feedback mechanisms, including particle trapping and binding by benthic plants that increase water clarity, and by oxygen effects on benthic nutrient recycling efficiency. Observations in Bay tributaries undergoing recent reductions in nutrient input indicate relatively rapid recovery of some ecosystem functions but lags in the response of others.
Many estuarine and coastal marine ecosystems have increasingly experienced degradation caused by multiple stressors. Anthropogenic pressures alter natural ecosystems and the ecosystems are not considered to have recovered unless secondary succession has returned the ecosystem to the pre-existing condition or state. However, depending upon the scales of time, space and intensity of anthropogenic disturbance, return along the historic trajectory of the ecosystem may: (1) follow natural restoration though secondary succession; (2) be re-directed through ecological restoration, or (3) be unattainable. In order to address the gaps in knowledge about restoration and recovery of estuarine and coastal ecosystems, this special feature includes the present overview and other contributions to provide a synthesis of our knowledge about recovery patterns, rates and restoration effectiveness. From the 51 examples collated in this contribution, we refine the recovery from the list of stressors into six recovery mechanisms: (1) recovery from sediment modification, which includes all aspects of dredging and disposal; (2) recovery by complete removal of stressors limiting natural ecosystem processes, which includes tidal marsh and inundation restoration; (3) recovery by speed of organic degradation, which includes oil discharge, fish farm wastes, sewage disposal, and paper mill waste; (4) recovery from persistent pollutants, which includes chemical discharges, such as TBT; (5) recovery from excessive biological removal, related to fisheries and (6) recovery from hydrological and morphological modification. Drawing upon experience both from these many examples and from an example of one comprehensive study, we show that although in some cases recovery can take
The present paper deals with an estimation of the water quality of the Struma river. Long-term trends, seasonal patterns and
data set structures are studied by the use of statistical analysis. Nineteen sampling sites along the main river stream and
different tributaries were included in the study. The sites are part of the monitoring net of the region of interest. Seventeen
chemical indicators of the surface water have been measured in the period 1989–1998 in monthly intervals. It is shown that
the water quality is relatively stable throughout the monitoring period, which is indicated by a lack of statistically significant
trends for many of the sites and by chemical variables. Several seasonal patterns are observed at the sampling sites and four
latent factors are identified as responsible for the data set structure.
A review of published literature on the sensitivity of corals to turbidity and sedimentation is presented, with an emphasis on the effects of dredging. The risks and severity of impact from dredging (and other sediment disturbances) on corals are primarily related to the intensity, duration and frequency of exposure to increased turbidity and sedimentation. The sensitivity of a coral reef to dredging impacts and its ability to recover depend on the antecedent ecological conditions of the reef, its resilience and the ambient conditions normally experienced. Effects of sediment stress have so far been investigated in 89 coral species (~10% of all known reef-building corals). Results of these investigations have provided a generic understanding of tolerance levels, response mechanisms, adaptations and threshold levels of corals to the effects of natural and anthropogenic sediment disturbances. Coral polyps undergo stress from high suspended-sediment concentrations and the subsequent effects on light attenuation which affect their algal symbionts. Minimum light requirements of corals range from <1% to as much as 60% of surface irradiance. Reported tolerance limits of coral reef systems for chronic suspended-sediment concentrations range from <10 mg L(-1) in pristine offshore reef areas to >100 mg L(-1) in marginal nearshore reefs. Some individual coral species can tolerate short-term exposure (days) to suspended-sediment concentrations as high as 1000 mg L(-1) while others show mortality after exposure (weeks) to concentrations as low as 30 mg L(-1). The duration that corals can survive high turbidities ranges from several days (sensitive species) to at least 5-6 weeks (tolerant species). Increased sedimentation can cause smothering and burial of coral polyps, shading, tissue necrosis and population explosions of bacteria in coral mucus. Fine sediments tend to have greater effects on corals than coarse sediments. Turbidity and sedimentation also reduce the recruitment, survival and settlement of coral larvae. Maximum sedimentation rates that can be tolerated by different corals range from <10 mg cm(-2) d(-1) to >400 mg cm(-2) d(-1). The durations that corals can survive high sedimentation rates range from <24 h for sensitive species to a few weeks (>4 weeks of high sedimentation or >14 days complete burial) for very tolerant species. Hypotheses to explain substantial differences in sensitivity between different coral species include the growth form of coral colonies and the size of the coral polyp or calyx. The validity of these hypotheses was tested on the basis of 77 published studies on the effects of turbidity and sedimentation on 89 coral species. The results of this analysis reveal a significant relationship of coral sensitivity to turbidity and sedimentation with growth form, but not with calyx size. Some of the variation in sensitivities reported in the literature may have been caused by differences in the type and particle size of sediments applied in experiments. The ability of many corals (in varying degrees) to actively reject sediment through polyp inflation, mucus production, ciliary and tentacular action (at considerable energetic cost), as well as intraspecific morphological variation and the mobility of free-living mushroom corals, further contribute to the observed differences. Given the wide range of sensitivity levels among coral species and in baseline water quality conditions among reefs, meaningful criteria to limit the extent and turbidity of dredging plumes and their effects on corals will always require site-specific evaluations, taking into account the species assemblage present at the site and the natural variability of local background turbidity and sedimentation.
The effects of marine aquaculture on the environment were evaluated by studying the water quality of San Pedro river, a canal located within the Bay of Cádiz (SW of Spain). Marine aquaculture, both extensive and intensive, is one of the most important activities carried out in this area. Several facilities are located on this river, the most important being devoted to the intensive culture of Gilthead Seabream (Sparus aurata). The characterization of the water consisted of the evaluation of the variation of several parameters along the river and during different seasons. These parameters were pH, temperature, salinity, dissolved oxygen, suspended solids and nutrients (ammonium, nitrite, nitrate and phosphate). With a water quality criteria based on local laws, a significant but not dangerous pollution was observed in the area, with ammonium and suspended solids being the most significant pollutants.
Aerial roots are a common adaptation of mangrove trees to their saline wetland habitat, allowing root respiration in the anaerobic substrate. While mangroves flourish on sedimentary shorelines, it is shown here that excess input of sediment to mangroves can cause death of trees owing to root smothering. Descriptions of 26 cases were found in the literature or described here, where mangroves have been adversely affected by sediment burial of roots. The impacts ranged from reduced vigour to death, depending on the amount and type of sedimentation, and the species involved. There are insufficient data to establish specific tolerances. For rehabilitation, where the disturbance was a past event, the elevation change must be assessed in selection of species for replanting, and field trials are required in areas where rapid accretion is an ongoing problem.
To examine the influence of river discharge on plankton metabolic balance in a monsoon driven tropical estuary, daily variations in physico-chemical and nutrients characteristics were studied over a period of 15 months (September 2007 to November 2008) at a fixed location (Yanam) in the Godavari estuary, India. River discharge was at its peak during July to September with a sharp decrease in the middle of December and complete cessation thereafter. Significant amount of dissolved inorganic nitrogen (DIN, of 22–26 μmol l−1) and dissolved inorganic phosphate (DIP, of 3–4 μmol l−1) along with suspended materials (0.2–0.5 g l−1) were found at the study region during the peak discharge period. A net heterotrophy with low gross primary production (GPP) occurred during the peak discharge period. The Chlorophyll a (Chl a) varied between 4 and 18 mg m−3 that reached maximum levels when river discharge and suspended loads decreased by >75% compared to that during peak period. High productivity was sustained for about one and half months during October to November when net community production (NCP) turned from net heterotrophy to autotrophy in the photic zone. Rapid decrease in nutrients (DIN and DIP by ∼15 and 1.4 μmol l−1, respectively) was observed during the peak Chl a period of two weeks. Chl a in the post monsoon (October–November) was negatively related to river discharge. Another peak in Chl a in January to February was associated with higher nutrient concentrations and high DIN:DIP ratios suggest possible external supply of nitrogen into the system. The mean photic zone productivity to respiration ratio (P:R) was 2.38 ± 0.24 for the entire study period (September 2007–November 2008). Nevertheless, the ratio of GPP to the entire water column respiration was only 0.14 ± 0.02 revealing that primary production was not enough to support water column heterotrophic activity. The excess carbon demand by the heterotrophs could be met from the allochthonous inputs of mainly terrestrial origin. Assuming that the entire phytoplankton produced organic material was utilized, the additional terrestrial organic carbon supported the total bacterial activity (97–99%) during peak discharge period and 40–75% during dry period. Therefore, large amount of terrestrial organic carbon is getting decomposed in the Godavari estuarine system.
Dead zones in the coastal oceans have spread exponentially since the 1960s and have serious consequences for ecosystem functioning.
The formation of dead zones has been exacerbated by the increase in primary production and consequent worldwide coastal eutrophication
fueled by riverine runoff of fertilizers and the burning of fossil fuels. Enhanced primary production results in an accumulation
of particulate organic matter, which encourages microbial activity and the consumption of dissolved oxygen in bottom waters.
Dead zones have now been reported from more than 400 systems, affecting a total area of more than 245,000 square kilometers,
and are probably a key stressor on marine ecosystems.
The rapid growth of aquaculture has raised the environmental concern about the conversion of ecologically important areas such as mangroves and agricultural lands. The study explored the impact of shrimp aquaculture on land use change in India’s coastal wetlands using Landsat satellite data, geographical information system techniques and field verification. From 1988 to 2013, the area under aquaculture has grown by 879 %, which brought the tremendous changes in the coastal land use pattern. Mangrove and agriculture lands have been used for 5.04 % and 28.10 % of the aquaculture growth. Mudflats, scrublands, saltpan, and waterbodies have contributed to 51.65 %, 1.76 %, 1.73 % and 2.37 % of the aquaculture area expansion respectively. Mangrove areas have undergone severe changes due to gain and loss at different places. Environmental factors influenced the changes in mangroves, and the overall extent of mangrove has increased by 13.44 %. Construction activities and aquaculture have reduced the agricultural land by 3.52 % and 0.53 % respectively. The variation between the actual area under shrimp aquaculture and the Coastal Aquaculture Authority approved area indicate that the larger extent of shrimp farm operates without approval. Implementation of an intensive monitoring program for strict adherence to coastal aquaculture regulation laws will be helpful for the sustainability of coastal resources as well as aquaculture.
Stable isotopes are used to identify and track nitrogen (N) sources to water bodies and thus can be used to ascertain the N source(s) used by the phytoplankton in those systems. To focus this tool for a particular harmful algal species, however, the fundamental patterns of N isotope fractionation by that organism must first be understood. While literature is available describing N isotope fractionation by diatoms and coccolithophores, data are lacking regarding dinoflagellates. Here we investigated the effects of N chemical form on isotope fractionation (Δ) and toxin content using isolates of the dinoflagellate Alexandrium catenella in single-N and mixed-N experiments. Growth of A. catenella exclusively on nitrate (NO3–), ammonium (NH4⁺), or urea resulted in Δ of 2.7 ± 1.4, 29 ± 9.3, or 0.3 ± 0.1, respectively, with the lowest cellular toxicity reported during urea utilization. Cells initially utilized NH4⁺ and urea when exposed to mixed-N medium and only utilized NO3– after NH4⁺ decreased below 2 to 4 μM. This pattern of N preference was similar across all N treatments, suggesting that there is no effect of preconditioning on N chemical preference by A. catenella. In NO3–- and urea-rich environments, the δ¹⁵N of A. catenella would resemble the source(s) of N utilized, supporting this tool’s utility as a tracer of N source(s) facilitating bloom formation, but caution is advisable in NH4⁺-rich environments, where the large Δ value could lead to misinterpretation of the signal.
Mangrove forests of India are globally unique with the highest record of biodiversity, gifted with the mangrove genetic paradise at Bhitarkanika, and the globally threatened wildlife species in the Sundarbans. The Sundarbans of India and Bangladesh is the only largest mangrove forest in the world colonized by the Royal Bengal Tigers. Mangroves are dense and floristically diverse along the east coast of India and the Andaman and Nicobar Islands. They are largely distributed in the high energy tidal coast of two extreme conditions: (i) humid and wet in Sundarbans with rich biodiversity, and (ii) arid and dry in Gujarat with low biodiversity. Despite increasing pressures, the mangrove cover in India increases annually at the rate of 1.2%, as against the global mangrove cover that disappears at 0.66%. However, India has a large track of sparse mangrove stand. This article discusses the present status of mangrove forests, conservation and management strategies being followed successfully in India, and recommends the future directions for mangrove restoration, improvisation of sparse stands, participatory management, and quality publications on mangrove research.
As aquaculture production increases with the rising global demands, its impact on the environment is escalating. Releasing aquaculture effluents to natural water bodies is becoming a challenge as effluents are often rich in organic and inorganic nutrients that lead to environmental deterioration. Discharges of nitrogen (N) and phosphorous (P) have received a great deal of attention from scientists and environmentalists as they disturb the natural balance of aquatic ecosystems. In this chapter, factors that govern N and P loading to the environment through aquaculture and the remediation measures that could be adopted are discussed.
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During dredging operation, fine sediment is released in the navigation channel of the Port of Townsville, Australia, as a result of mechanical disturbance of the bed and of the overflow from the storage tanks of the dredger. Some of this sediment is advected away
from the dredging site toward the beach and reef areas and could result in environmental damage if not managed properly. Field monitoring was conducted for salinity, temperature, suspended sediment, and acoustic profiles at several sites before and after dredging. Laboratory investigations
on the effect of sediment concentration, turbulence, and floe size on the clearing of a suspension column were also undertaken. Results of both field and laboratory investigations show faster clearing in quiescent conditions than in turbulent conditions. Turbulence at low levels disturbs the
dewatering microchannels of the fluid mud layer. As turbulence increases the effect of floe breakage and settling retardation also become important.
The research depicts the spatial and temporal variation of major and trace metals in marine sediments at various monitoring stations of Dhamra estuary, Bay of Bengal, Odisha. The concentration and distribution of selected metals in surface sediments of the estuary were studied in order to assess the spatial extent of anthropogenic inputs viz., mining activities and to estimate the effects of seasonal variations on geochemical processes in this particular tropical estuarine system. Surface sediments reflect the presence of trace and major metals in parts per million, and the concentrations vary in the range of Cu (0.083 to 127.2), Ni (17.35 to 122.8), Co (1.2 to 31.58), Pb (0.8 to 95.86), Zn (12.1 to 415), Cd (0 to 11) and Cr (35.21 to 5,890), Fe (7,490 and 169,100), Mn (20 to 69,188), Ca (10 to 10,520), Mg (990 to 28,750), Na (300 to 51,700), and K (1,100 to 30,010). The comparison of spatial distribution of metal contents using GIS in marine sediments indicates that there is a substantial anthropogenic input in the Dhamra estuary. The enrichment of Cr is ascribed to the sedimentation of Brahmani River, passing through the mining region and discharging Cr pollutant to the sea. Similarly, the sources of Cd are attributable to corrosion-resistant paints used by a large number of trawlers. Contamination factor has been calculated for various metals to assess the degree of pollution. As per Hakanson's classification, Cr indicates very high contamination with considerable contamination of Cd, whereas moderate contamination of Pb, Zn, and Mn are observed in marine sediments. Pollution load index also indicate that there is deterioration of site quality in premonsoon season, which almost attains the baseline level in post monsoon and perfection in monsoon season (Tomlinson et al. (Helgolander Wissenschaftliche Meeresuntersuchungen, 33, 566-572, 1980)). The geoaccumulation index shows that the metal concentrations in sediments can be considered as background levels except Cr and Cd. The geoaccumulation index shows that Cr is moderately contaminated and it is higher in offshore region in post monsoon and monsoon than premonsoon season. All the calculated indices show that Cr and Cd levels are more than the desired limits in the marine sediments. Multivariate statistical analysis evaluates the plausible sources of contaminants, attributing to mining, industrial, and urban wastes by way of Brahmani River discharging to the estuarine region.
Significant concentrations of nitrite NO{sub 2}{sup {minus}} were produced from the photodegradation of humic substances (HS) isolated from a variety of natural waters in coastal North Carolina. Nitrite concentrations were 40--118% higher after light exposure relative to initial levels, while no statistical differences were observed in dark controls before and after irradiation. The amount of nitrite produced upon irradiation was positively correlated to the concentration of HS added and to the length of irradiation. The average production rate, normalized to both humic substance concentration and time of light exposure, for all HS studied ranged from 9.7 to 17 [nM (W-h){sup {minus}1} m{sup {minus}2} mg{sup {minus}1}] {times} 10{sup 5}. This translates into an average yearly nitrite production of 2 {times} 10{sup 6} mol yr{sup {minus}1} in the top one meter of Onslow Bay. When natural waters were irradiated, changes in nitrite were influenced by both initial nitrite and humic substance concentrations. The rate of nitrite photochemical formation in typical coastal waters was smaller from its direct photolysis rate and smaller than reported rates of ammonium generation via DOM photodegradation and of the same order of magnitude as NH{sub 4}{sup +} incorporation during humification. The photochemical release of biologically available nitrite from biologically refractory humic substances has significant implications with respect to nitrite biogeochemistry and N cycling in natural waters and suggests HS bound N is more biogeochemically labile than previously thought.
Mangrove ecosystem being suitable for brackish water shrimp culture, large number of aquaculture ponds have been developed in the periphery of Bhitarkanika National Park area of Orissa, India. These ponds are regularly fed by brackish water from nearby Brahmani-Baitarani river system and the same water is ultimately discharged into the mangrove ecosystem. In the present study, some physico-chemical parameters such as pH, temperature, conductivity, dissolved oxygen, calcium, magnesium, total hardness, chlorine, phosphate, nitrate, and total dissolved solid contents of seven aquaculture ponds have been analysed for assessment of pollution status with respect to river water taken as control. Studies were undertaken for a period of six months from November 2005 to April 2006 during which the physico-chemical parameters were compared with the water quality standard of Bureau of Indian Standard (BIS) and Central and the State Pollution Control Board (PCB). pH values of the aquaculture ponds range between 5.63-8.5 as against the value of standard water quality i.e.6.5-8.5. Nitrate, total hardness, calcium, magnesium, phosphate, and chlorine contents show variation within different sites. Dissolved oxygen values vary from 3.0 to 8.3 mg/L during six months of investigation. Some of the sites show higher dissolved oxygen values than the permissible limits (4.0-5.0 mg/L) prescribed by PCB and BIS indicating that these waters do not pose any threat to aquatic life. The study indicates that the aquaculture pond water at present do not possess any pollution problem for the mangrove ecosystem.
It is important to know the ultimate role of small copepods in structuring mesozooplankton community
pattern and diversity on an estuary-coastal gradient. Here multivariate analyses were used to elucidate
this in the Godavari estuary, on the east coast of India. During May 2002, corresponding to the spring
intermonsoon, mesozooplankton were sampled from 4 GPS fixed stations in the estuarine reaches of
River Godavari and 19 in the coastal waters where Godavari enters the Bay of Bengal. There were 91
mesozooplankton taxa represented by 23 divergent groups. Copepods were by far the most prominent in
terms of species richness, numerical abundance, and widespread distribution followed by appendicularians.
Small copepods of families Paracalanidae, Acartiidae, Oithonidae, Corycaeidae, Oncaeidae, and
Euterpinidae dominated. There were differing regional mesozooplankton/copepod communities, that
segregated the estuary-coastal sites into different biotic assemblages: Group-I representing the estuary
proper, Group-II estuary mouth and near shore, Group-III the intermediate coastal stations and Group-IV
the coastal-offshore waters. Alpha (SRp, H0 , J0 , D*) and beta diversity (MVDISP, b, b-dissimilarity) measures
varied noticeably across these assemblages/areas. The significant correlation of small copepod
abundance with total mesozooplankton abundance and biomass (mgDM.m�3) in the estuarine (r: 0.40)
and coastal (r: 0.46e0.83) waters together with a regression analysis of diversity measures have revealed
the importance of small copepods in the overall mesozooplankton/copepod community structure. There
were ‘characterizing’ and ‘discriminating’ species, responsible for the observed assemblage patterns.
Mesozooplankton/copepod community structure and the size-spectra observed during this study indicate
an estuarine-coastal gradient in plankton tropho-dynamics that may shift between a microbial
dominated system inside the estuary and mixotrophy in the coastal waters. The functional diversity of
copepods revealed features of an effective niche sharing and efficient utilization of the coastal resources
by the resident zooplankton some of which are brought out for the first time showing a tropical estuary
under the influence of monsoons. The present study also illustrates the importance of, and advocates the
need for, incorporating complementary or additional biodiversity measures while describing biotic
communities vis-à-vis environmental gradients.
The environmental impact of marine fish-farming depends very much on species, culture method, stocking density, feed type, hydrography of the site and husbandry practices. In general, some 85% of phosphorus, 80–88% of carbon and 52–95% of nitrogen input into a marine fish culture system as feed may be lost into the environment through feed wastage, fish excretion, faeces production and respiration. Cleaning of fouled cages may also add an organic loading to the water, albeit periodically. Problems caused by high organic and nutrient loadings conflict with other uses of the coastal zone. The use of chemicals (therapeutants, vitamins and antifoulants) and the introduction of pathogens and new genetic strains have also raised environmental concerns.
Synchronous anthropogenic effects on marine coastal systems, particularly since World War II, make it difficult to separate effects of fishing from terrestrial inputs, especially those caused by nutrient runoff. Natural enrichment is vital to productive fisheries, but over the long term anthropogenic nutrient impacts generally predominate over fishery effects in semi-enclosed seas and affect biodiversity and susceptibility to fishing. Such impacts on marine fisheries beyond natural levels of outflow are referred to here as marine catchment basin (MCB) effects. They require coordinated actions within the catchment area to control them, since fisheries management actions alone are unlikely to be effective in rectifying ecosystem impacts. Net nutrient inflows may be positive or negative, depending on intensity and degree of retention by the receiving marine system and may promote ecosystem change and lead to ecological dominance by exotic species. Initially positive effects of enrichment may disguise the urgent need for coordinated environmental and fishery management measures in semi-enclosed seas. Fisheries impacts are serious, but may be secondary and synergistic, but potentially catastrophic under hypoxic conditions since eutrophic processes make demersal ecosystems particularly sensitive to disturbance of bottom habitats. Hence, fishing with bottom gear may impact bottom fauna and demersal resources within or above organic sediments affected by eutrophic processes and hypoxia. These effects show up as changes in the ratio of pelagic to demersal landings, and support broad-brush comparative studies of areas subject to different levels of environmental impact. 2000 International Council for the Exploration of the Sea Key words: anthropogenic effects, ecosystem impacts on fishing, (European) semi-enclosed seas, marine eutrophication, nutrients.
Despite a recent review concluding that there is little or no reason to expect that the production of fish and other animals
will increase with nutrient enrichment or eutrophication, there is a variety of evidence that anthropogenic nutrients can
stimulate secondary production in marine ecosystems. Unique multiple-year fertilization experiments were carried out over
fifty years ago in Scottish sea lochs that showed dramatic increases in the abundance of benthic infauna and greatly enhanced
growth of fish as a result of inorganic nitrogen (N) and phosphorus (P) additions. These experiments appear to have provided
a good qualitative model for the responses of the Baltic Sea to nutrient enrichment and resulting eutrophication. Historical
comparisons by others have shown that the weight of benthic animals per unit area above the halocline in the Baltic is now
up to 10 or 20 times greater than it was in the early 1920s and that the total fish biomass in the system may have increased
8 fold between the early part of the 1900s and the 1970s. While there are no similar data for the highly enriched central
and southern North Sea, there is convincing evidence that the growth rates of plaice, sole, and other species have increased
there since the 1960s or 1970s. Cross-system comparisons have also shown that there are strong correlations between primary
production and the production and yield of fish and the standing crop and production of benthic macrofauma in phytoplankton-dominated
marine ecosystems. Concerns over the growing nutrient (especially N) enrichment of coastal marine waters are clearly valid
and deserve the attention of scientists and managers, but the recent demonizing of N ignores the fact that nutrients are a
fundamental requirement for producing biomass. Decisions regarding the amount of N or P that will be allowed to enter marine
ecosystems should be made with the full knowledge that there may be tradeoffs between increases in water clarity and dissolved
oxygen and the abundance of oysters, clams, fish, and other animals we desire.
The distilling effect of evaporation and the diluting effect of precipitation on salinity at two estuarine sites in the humid
subtropical setting of the Indian River Lagoon, Florida, were evaluated based on daily evaporation computed with an energy-budget
method and measured precipitation. Despite the larger magnitude of evaporation (about 1,58 mm yr−1) compared to precipitation (about 1,180 mm yr−1) between February 2002 and January 2004, the variability of monthly precipitation induced salinity changes was more than
twice the variability of evaporation induced changes. Use of a constant, mean value of evaporation, along with measured values
of daily precipitation, were sufficient to produce simulated salinity changes that contained little monthly (root-mean-square
error = 0.33‰ mo−1 and 0.52‰ mo−1 at the two sites) or cumulative error (<1‰ yr−1) compared to simulations that used computed daily values of evaporation. This result indicates that measuring the temporal
variability in evaporation may not be critical to simulation of salinity within the lagoon. Comparison of evaporation and
precipitation induced salinity changes with measured salinity changes indicates that evaporation and precipitation explained
only 4% of the changes in salinity within a flow-through area of the lagoon; surface water and ocean inflows probably accounted
for most of the variability in salinity at this site. Evaporation and precipitation induced salinity changes explained 61%
of the variability in salinity at a flow-restricted part of the lagoon.
Pollutants, originating from both land and sea, are responsible for significant lethal and sub-lethal effects on marine life.
Pollution impacts all trophic levels, from primary producers to apex predators, and thus interferes with the structure of
marine communities and consequently ecosystem functioning. Here we review the effects of sediments, eutrophication, toxics
and marine litter. All are presently major concerns in Southeast Asia (SE Asia) and there is little indication that the situation
is improving. Approximately 70% of SE Asia’s human population lives in coastal areas and intensive farming and aquaculture,
rapid urbanization and industrialisation, greater shipping traffic and fishing effort, as well as widespread deforestation
and nearshore development, are contributing towards the pollution problem. As SE Asia encompasses approximately 34% of the
world’s reefs and between a quarter and a third of the world’s mangroves, as well as the global biodiversity triangle formed
by the Malay Peninsular, the Philippines, and New Guinea, the need to reduce the impacts of marine pollution in this region
is all the more critical.
KeywordsCoral reef-Eutrophication-Mangrove-Marine litter-Seagrass-Sediment-Toxics
Puget Sound is a large estuary complex in the U.S. Pacific Northwest that is home to a diverse and economically important ecosystem threatened by anthropogenic impacts associated with climate change, urbanization, and ocean acidification. While ocean acidification has been studied in oceanic waters, little is known regarding its status in estuaries. Anthropogenically acidified coastal waters upwelling along the western North American continental margin can enter Puget Sound through the Strait of Juan de Fuca. In order to study the combined effects of ocean acidification and other natural and anthropogenic processes on Puget Sound waters, we made the first inorganic carbon measurements in this estuary on two survey cruises in February and August of 2008. Observed pH and aragonite saturation state values in surface and subsurface waters were substantially lower in parts of Puget Sound than would be expected from anthropogenic carbon dioxide (CO2) uptake alone. We estimate that ocean acidification can account for 24–49% of the pH decrease in the deep waters of the Hood Canal sub-basin of Puget Sound relative to estimated pre-industrial values. The remaining change in pH between when seawater enters the sound and when it reaches this deep basin results from remineralization of organic matter due to natural or anthropogenically stimulated respiration processes within Puget Sound. Over time, however, the relative impact of ocean acidification could increase significantly, accounting for 49–82% of the pH decrease in subsurface waters for a doubling of atmospheric CO2. These changes may have profound impacts on the Puget Sound ecosystem over the next several decades. These estimates suggest that the role ocean acidification will play in estuaries may be different from the open ocean.
Daily variations in nutrients were monitored for 15 months (September 2007–November 2008) in the Godavari estuary, Andhra Pradesh, India, at two fixed locations. River discharge has significant influence on nutrients loading to the estuary, which peaks during June–August (peak discharge period; monsoon) whereas exchanges at the sediment–water interface, groundwater and rainwater contribute significantly during other period. Despite significant amount of nutrients brought by discharge to the study region, phytoplankton biomass, in terms of chlorophyll-a (Chl a), did not increase significantly due to high suspended load and shallow photic depth. Nutrients showed downward gradient towards downstream of the estuary from upstream due to dilution by nutrient poor seawater and biological uptake. The N:P ratios were higher than Redfield ratio in both upstream and downstream of the estuary during no discharge period suggesting PO4 to be a limiting nutrient for phytoplankton production, at levels <0.10 μmol L−1. On the other hand, Si:N ratios were always more than unity during entire study period at both the stations indicating that Si(OH)4 is not a limiting nutrient. Our results suggest that suspended matter limits phytoplankton biomass during peak discharge period whereas PO4 during no discharge period.
Multivariate statistical techniques, such as cluster analysis (CA), principal component analysis (PCA), factor analysis (FA) and discriminant analysis (DA), were applied for the evaluation of temporal/spatial variations and the interpretation of a large complex water quality data set of the Fuji river basin, generated during 8 years (1995–2002) monitoring of 12 parameters at 13 different sites (14 976 observations). Hierarchical cluster analysis grouped 13 sampling sites into three clusters, i.e., relatively less polluted (LP), medium polluted (MP) and highly polluted (HP) sites, based on the similarity of water quality characteristics. Factor analysis/principal component analysis, applied to the data sets of the three different groups obtained from cluster analysis, resulted in five, five and three latent factors explaining 73.18, 77.61 and 65.39% of the total variance in water quality data sets of LP, MP and HP areas, respectively. The varifactors obtained from factor analysis indicate that the parameters responsible for water quality variations are mainly related to discharge and temperature (natural), organic pollution (point source: domestic wastewater) in relatively less polluted areas; organic pollution (point source: domestic wastewater) and nutrients (non-point sources: agriculture and orchard plantations) in medium polluted areas; and organic pollution and nutrients (point sources: domestic wastewater, wastewater treatment plants and industries) in highly polluted areas in the basin. Discriminant analysis gave the best results for both spatial and temporal analysis. It provided an important data reduction as it uses only six parameters (discharge, temperature, dissolved oxygen, biochemical oxygen demand, electrical conductivity and nitrate nitrogen), affording more than 85% correct assignations in temporal analysis, and seven parameters (discharge, temperature, biochemical oxygen demand, pH, electrical conductivity, nitrate nitrogen and ammonical nitrogen), affording more than 81% correct assignations in spatial analysis, of three different sampling sites of the basin. Therefore, DA allowed a reduction in the dimensionality of the large data set, delineating a few indicator parameters responsible for large variations in water quality. Thus, this study illustrates the usefulness of multivariate statistical techniques for analysis and interpretation of complex data sets, and in water quality assessment, identification of pollution sources/factors and understanding temporal/spatial variations in water quality for effective river water quality management.
The worldwide exponential growth of off-shore mariculture is raising severe concerns about the impacts of this industry on marine habitats and their biodiversity. We investigated the metazoan meiofaunal response to fish-farm impact in four regions of the Mediterranean Sea. Meiofaunal assemblages were investigated in two habitats (seagrass meadows of Posidonia oceanica and non-vegetated soft bottoms) comparing sites receiving faeces and uneaten food pellets from fish farms to control sites. We report here that, consistently across different regions, the meiofaunal abundance typically responded positively to fish-farm effluents. Biodeposition caused also significant changes in assemblage structure and the reduction in the richness of higher meiofaunal taxa, but the multivariate analysis of variance revealed that the effects were region- and habitat-specific. In non-vegetated systems, three of the four regions investigated displayed significant effects of the fish farms on richness of meiofaunal taxa. In vegetated habitats, meiofauna did not respond to biodeposition (except in one region), suggesting that seagrass meadows can mask the effects of fish-farm effluents on benthic biodiversity. We conclude that different indicators of fish-farm impact are needed in vegetated and non-vegetated benthic systems.
This study presents the usefulness of multivariate statistical techniques, such as correlation matrix, cluster analysis, and factor analysis, for the evaluation and interpretation of complex water quality data sets of Brahmani-Koel river along the Rourkela Industrial Complex, India, and the apportionment of pollution sources/factors. The correlation study suggests that dissolved heavy metals, biochemical oxygen demand (BOD), and chemical oxygen demand (COD) are contributed by anthropogenic sources. The results of R-mode factor analyses revealed that anthropogenic contributions are responsible for increase in metals of the river water, which is mainly responsible for contamination of the river. It also reflected that the level of pollution in the river was very high. The factor score plot and loading plot have been drawn, which indicate that the polluted stations are identified by the heavy metals. The relationships among the stations are highlighted by cluster analysis, represented in dendograms to categorize different levels of contamination. An attempt has been made to study the degree of contamination of the river waters by using a tool like enrichment ratio (ER). The ER for heavy metal concentrations concluded that metals like Ni, Co, Cr, and Fe are showing high enrichment with respect to global background and metal ions like Fe, Mn, Cu, and Zn show high enrichment with respect to local background.
Factor analysis is applied to 28 groundwater samples collected from wells in the coastal blackfoot disease area of Yun-Lin, Taiwan. Correlations among 13 hydrochemical parameters are statistically examined. A two-factor model is suggested and explains over 77.8% of the total groundwater quality variation. Factor 1 (seawater salinization) includes concentrations of EC, TDS, Cl(-), SO(4)(2-), Na(+), K(+) and Mg(2+), and Factor 2 (arsenic pollutant) includes concentrations of Alk, TOC and arsenic. Maps are drawn to show the geographical distribution of the factors. These maps delineate high salinity and arsenic concentrations. The geographical distribution of the factor scores at individual wells does not reveal the sources of the constituents, which are instead, deduced from geological and hydrological evidence. The areas of high seawater salinization and arsenic pollution correspond well to the groundwater over-pumping area. Over-pumping of the local groundwater causes land subsidence and gradual salinization by seawater. The over-pumping also introduces excess dissolved oxygen that oxidizes the immobile minerals, releases arsenic by reductive dissolution of arsenic-rich iron oxyhydroxides and increases the arsenic concentration in water. The over-extraction of groundwater is the major cause of groundwater salinization and arsenic pollution in the coastal area of Yun-Lin, Taiwan.
Dredging and port construction around coral reefs. The World Association for Waterborne Transport Infrastructure (PIANC)
- Pianc
PIANC, 2010. Dredging and port construction around coral reefs. The World Association
for Waterborne Transport Infrastructure (PIANC), Report No. 108, 75.