Metal contamination in water, sediment and biota from a semi-enclosed coastal area

Out of the blue: Hyperaccumulation of molybdenum in the Indo-Pacific sponge Theonella conica

Molybdenum is an essential micronutrient, but because of its toxicity at high concentrations, its accumulation in living organisms has not been widely demonstrated. In this study, we report that the marine sponge Theonella conica accumulates exceptionally high levels of molybdenum (46,793 micrograms per gram of dry weight) in a wide geographic distribution from the northern Red Sea to the reefs of Zanzibar, Indian Ocean. The element is found in various sponge body fractions and correlates to selenium. We further investigated the microbial composition of the sponge and compared it to its more studied congener, Theonella swinhoei. Our analysis illuminates the symbiotic bacterium Entotheonella sp. and its role in molybdenum accumulation. Through microscopic and analytical methods, we provide evidence of intracellular spheres within Entotheonella sp. that exhibit high molybdenum content, further unraveling the intricate mechanisms behind molybdenum accumulation in this sponge species and its significance in the broader context of molybdenum biogeochemical cycling.

Partitioning of metals in the tissues and cytosolic fraction of Cerastoderma edule

The concentrations of Cd, Cu and Zn have been determined in the tissues and the cytosolic fraction of the common cockle, Cerastoderma edule, collected from sediments in the Tamar, Plym and Avon estuaries (South West, England). Metal concentrations in the tissues of C. edule from the Avon were lower than those from the Tamar and Plym, except for Cu in the digestive gland. Significant statistical relationships were only obtained between the total sedimentary metal concentrations and Cd in the body of C. edule and Cu in the digestive gland. The cytosolic fraction was extracted from each of the tissues and separated for protein analysis thereby allowing determination of the metal contents in high molecular weight (HMW) compounds, metallothionein-like proteins (MTLP) and very low molecular weight (VLMW) compounds. The digestive glands of C. edule from the Avon had relatively low concentrations of MTLP, whereas MTLP concentrations in the digestive gland of cockles from the Tamar and Plym were higher. The cytosolic fraction of C. edule had relatively low total Cd and Cu concentrations associated with MTLP, whereas Zn was preferentially associated with the HMW and the VLMW components. The results are relevant to metal distributions in C. edule and the role of cytosols in the management of metals by C. edule and other invertebrates.

The use of marine sponge species as a bioindicator to monitor metal pollution in Red Sea, Saudi Arabia

The existing data on trace elements of benthic sea organisms is scarce. Yet, the pressing issue of environmental contamination has spurred a surge in the use of organisms as biomonitors. In this study, sediment cores were sampled with the sponges, and metal concentrations were determined in both samples using ICP-MS. The mean concentrations of metals in benthic sediments and sponge species analyzed in this study differed significantly (Sediment > Phorbas species > Negombata magnifica > Callyspongia species > Amphimedon chloros). This could be due to the varying capacity of each sponge species to accumulate a particular metal by different means. Negombata magnifica and Phorbas species appear to be indicators, accumulators, or hyper-accumulators of Cu and Mn, while Callyspongia species is an indicator, accumulator, or hyper-accumulator of Cu only due to bioconcentration factor > 1 for the aforementioned metals. Concentrations of Cu and As in sediment were below the Effects Range Median but above the Effects Range Low threshold, hence the need to give more attention to these metals. This research provides a baseline dataset for designing monitoring strategies on this ecosystem and using sponge species for biomonitoring.

The sponge Oscarella lobularis (Porifera, Homoscleromorpha) as a suitable biomonitor of metallic contamination in Mediterranean coastal ecosystems

The biomonitoring of metallic contamination in marine ecosystems is often focused on animal species of commercial interest and in lesser extent on non-model marine invertebrates. The aim of this study was to compare the metal concentrations (Li, Al, Ti, Cr, Fe, Ni, Cu, Zn, As, Ag, Cd, Hg, Pb) in seven marine sponges with a particular interest in the homoscleromorph sponge Oscarella lobularis at different sites of the Bay of Marseille, France. Inter-species variabilities suggest that the seven sponge species studied accumulate metals differently. In O. lobularis, a multi-site analysis shows different bioaccumulation between the eight sampled populations. These inter-site differences may reflect differences in the hydrodynamic features and in past and present industrial activities. Because Oscarella lobularis shows a homogeneous metal accumulation pattern in comparison with the other tested species, it appears to be suitable for metal contamination biomonitoring in Mediterranean coastal waters, in particular of the coralligenous communities.

Assessing and predicting the changes for inorganic mercury and methylmercury concentrations in surface waters of a tidal estuary (Adour Estuary, SW France)

Total and dissolved concentrations of inorganic mercury (IHg) and methylmercury (MeHg) in water (Adour Estuary) were determined during three sampling campaigns and related to biogeochemical variables (nutrients, organic matter). Factors (sampling time, sample type) were included in analysis of covariance with effect separation. The urban estuary suffered historically from anthropogenic sources, however, decreased emissions have reduced Hg concentrations. Total IHg (0.51-3.42 ng L^-1) and MeHg (25-81 pg L^-1) concentrations are additively described by suspended particulate matter and particulate organic carbon. Higher total concentrations, carried by organic-rich particles, were found near specific discharge points (0.79-8.02 ng L^-1 and 34-235 pg L^-1 for IHg and MeHg, respectively). The associated high dissolved MeHg concentrations could not be explained only by biogeochemical variables. Better efficiency of the models is found for total than for dissolved concentrations. Models should be checked with other contaminants or with estuaries, suffering from downstream contamination.

Pollution gradient leads to local adaptation and small-scale spatial variability of communities and functions in an urban marine environment

Urbanization of coastal habitats, of which harbors and marinas are the paragon, has led to various ecological paradigms about their functioning. Harbor infrastructures offer new hard substrata that are colonized by a wide variety of organisms (biofouling) including many introduced species. These structures also modify hydrodynamism and contaminant dispersal, leading to strong disturbance gradients within them. Differences in sessile community structure have previously been correlated to these gradients at small spatial scale (<100 m). Local adaptation might be involved to explain such results, but as correlation is not causation, the present study aims to understand the causal link between the environmental gradients and community structure through a reciprocal transplant experiment among three sites of a marina (inner, middle, entrance). Our results highlighted strong small-scale spatial variations of contaminants (trace metals, PCB, pesticides, and PAH) in sediments and animal samples which have been causally linked to changes in community composition after transplant. But historical contingency and colonization succession also play an important role. Our results provided strong evidence for local adaptation since community structure, respiration, and pollutant uptake in Bugula neritina, as well as the metabolomes of B. neritina and Ciona intestinalis were impacted by the transplant with a disadvantage for individuals transplanted from the entrance to the inner location. The here observed results may thus indicate that the disturbance gradient in marinas might constitute a staple for selecting pollutant-resistant species and populations, causing local adaptation. This highlights the importance of conducting further studies into small scale local adaptation.

A risk assessment by metal contamination in a river used for public water supply

Aquatic ecosystems provide habitats for many organisms. Historically, riverbanks have always been inhabited and exploited for subsistence and navigation. The present study evaluates the contamination and ecological risks caused by potentially toxic elements in surface sediments of the Paraguaçu River, Bahia, Brazil. Seven sediments samples were collected, and eight heavy metals were determined employing inductively coupled plasma spectrometry mass (ICP-MS). The concentrations range as (mg kg^-1) found were 6.78-18.68 for lead, 14.21-42.16 for zinc, 27.61-48.63 for nickel, 2.03-6.50 for chromium, 6.06-12.90 for vanadium, 5.99-13.33 for cupper, 1.25-3.19 for cobalt, and 79.52-286.08 for manganese. Nickel showed significant enrichment (EF: 5.75; 7.62, and 14.11), followed by zinc, which showed moderate enrichment (EF: 2.16; 2.19, and 4.52). These enrichment levels are possible of anthropogenic origin. When the pollution index (PI) was evaluated, the elements V, Ni, Zn, Mn, Co, and Cu were strongly polluted (PI ≥3). In general, the pollution index (PI), geoaccumulation index (I_geo), enrichment factor (EF), and potential ecological risk indices (E_r and PERI) show that contaminated sediments have adverse effects on aquatic environments, especially for o Mn, Ni, Pb, V, and Zn.

Increasing arsenic accumulation as an implication of climate change: a case study using red algae

Climate change due to an increasing concentration of carbon dioxide in the atmosphere is a global issue. It can impact aquatic environments by affecting water flow, pollutant transformation and migration, and other toxicant-related effects. We assessed the interactive effects of temperature warming and pH changes on variations in accumulation of total arsenic (As_T) in the red alga Sarcodia suae at different levels of arsenite (As_III). Result showed that As_T variations in the alga were moderated by significant joint effects of warming temperature and/or increasing pH levels and their interactions with increasing As_III concentrations. Our study suggests possible deleterious impacts on macroalgal populations due to toxicological effects associated with prevailing environmental conditions. Therefore, improved pollution management, climate change adaptation, and mitigation strategies are needed to deal with current environmental issues and As aggravation.

Spatio-temporal assessment, sources and health risks of water pollutants at trace levels in public supply river using multivariate statistical techniques

The Joanes River is located in the northeast of Brazil, crosses the Camaçari Petrochemical Complex, the largest integrated industrial complex in the Southern Hemisphere, which has over 90 companies in the chemical and petrochemical industry. The present study aims to evaluate spatial distribution, seasonal variation and identify possible sources of trace metal contamination in surface water samples of the Joanes River. Samples were collected in the dry (December 2018) and rainy (August 2019) seasons. Analysis of trace elements (As, Cd, Cr, Cu, Ni, Mn and Pb) were performed by ICP-MS. A total of 60 water samples were obtained. Samples were analyzed using exploratory techniques such as principal component analysis (PCA) and cluster analysis (CA). It was possible to characterize the samples according to the seasonal variation. The formation of two groups was observed. Among these, samples from the rainy season presented the higher levels of metals in relation to the samples of the dry season. Natural and anthropic sources of metal contamination were identified using CA. Similarity was shown in the relationship between the metals As-Pb and Ni-Cd-Cr-Cu in the dry season, and Cd-Ni and Pb-As-Cr-Cu in the rainy season. Dermal absorption (HQderm) and ingestion hazard quotients (HQing) routes exhibited values of less than one for all the elements analyzed for adults and children, in both rainy and dry seasons. This indicated that the pollutants analyzed posed little or no health risk over a lifetime of exposure. According to international guidelines (US EPA), the values of Cu, Pb and Cr were above the limit established.

Investigation of heavy metals in the ballast water of ship tanks after and before the implementation of the ballast water convention: Bushehr Port, Persian Gulf

In this study, the amount of heavy metals such as Ni, Cd, Pb and Cu and some physiochemical factors including pH, temperature and total organic carbon (TOC) in the ballast water of the ships entering the Bushehr Port were measured for two years (cold and hot seasons) before and after the ballast water convention was enforced. The mean concentrations of Ni, Cd, Pb and Cu, before and after implementation of the convention were 46.55, 3.93, 5.36, 58.83 and 26.41, 2.12, 2.59, 23.54 ppb. It became clear that the concentrations of heavy metals after the implementation of the convention was lower in comparison and there was a significant difference (p < .05). It seems that continuous monitoring of the quality of the ballast water and determination of locations free of pollution and contamination in the Persian Gulf are necessary for ships that intend to exchange their ballast water in this Gulf.

The alga Ulva lactuca (Ulvaceae, Chlorophyta) as a bioindicator of trace element contamination along the coast of Sicily, Italy

The marine environment is subjected to ever-increasing levels of contamination, especially along the coastal areas with urban and industrial activities. Consequently, monitoring campaigns on large scales should be conducted on a regular basis for a better management of marine ecosystems. This study tested the capacity of the green alga Ulva lactuca to act as a bioindicator of trace elements along the coasts of Sicily (Italy). The concentrations of the metals Cd, Cr, Cu, Ni, Pb and Zn were analyzed in samples of water, sediments and U. lactuca thalli, which were collected in ten different sites at diverse levels of human impact. The results showed that U. lactuca can accumulate essential and non-essential elements at similar concentrations. The analysis of trace elements showed also that the metal content in U. lactuca is significantly correlated with the levels of trace elements in water and sediments. U. lactuca fits numerous features that make it one of the best bioindicators of marine pollution, also thanks to its worldwide distribution and capacity to accumulate trace elements under toxic conditions. The use of U. lactuca should be encouraged to set up large-scale monitoring programs, especially in highly impacted seas like the Mediterranean where U. lactuca is widespread.

Behavioural and brain biomarker responses in yellowfin bream (Acanthopagrus australis) after inorganic mercury ingestion

To assess the effects of inorganic mercury ingestion on fish general behaviour and brain biochemical markers (acetylcholinesterase - AChE; lipid peroxidation - LPO; glutathione S-transferase - GST; catalase - CAT), juvenile yellowfin bream (Acanthopagrus australis) were fed mercury dosed food (low = 0.7 mg kg^-1, medium = 2.4 mg kg^-1 and high = 6 mg kg^-1) or undosed food (control = 0.2 mg kg^-1) for up to 16 days (5 replicates per treatment). Behavioural indicators, LPO levels and GST activity significantly changed overtime, but were not affected by mercury concentration. In contrast, CAT activity was higher in exposed fish in comparison to controls after 4 days, but not after 8 and 16 days. An additional depuration treatment was evaluated and fish from this treatment were less active and had significantly lower LPO levels and CAT activity than fish constantly exposed to the medium treatment. Overall, results from the present study indicate that a diet containing inorganic mercury impaired yellowfin bream growth and initially affected fish brain CAT activity, however fish were able to recover even with continuous exposure.

Comparative study on the bioaccumulation and biotransformation of arsenic by some northeastern Atlantic and northwestern Mediterranean sponges

The bioaccumulation and biotransformation of arsenic (As) were studied in six representative marine sponges from the French Mediterranean and Irish Atlantic coasts. Methodologies were carefully optimized in one of the species on Haliclona fulva sponges for two critical steps: the sample mineralization for total As analysis by ICP-MS and the extraction of As species for HPLC-ICP-MS analysis. During the optimization, extractions performed with 0.6 mol L^-1 H₃PO₄ were shown to be the most efficient. Extraction recovery of 81% was obtained which represents the best results obtained until now in sponge samples. Total As analyses and As speciation were performed on certified reference materials and allow confirming the measurement quality both during the sample preparation and analysis. Additionally, this study represents an environmental survey demonstrating a high variability of total As concentrations among the different species, probably related to different physiological or microbial features. As speciation results showed the predominance of arsenobetaine (AsB) regardless of the sponge species, as well as the occurrence of low amounts of dimethylarsinic acid (DMA), arsenate (As(+V)), and unknown As species in some samples. The process responsible for As transformation in sponges is most likely related to sponges metabolism itself or the action of symbiont organisms. AsB is supposed to be implied in the protection against osmolytic stress. This study demonstrates the ability of sponges to accumulate and bio-transform As, proving that sponges are relevant bio-monitors for As contamination in the marine environment, and potential tools in environmental bio-remediation.

Marine sponges as a powerful tool for trace elements biomonitoring studies in coastal environment

In this work, we performed a comparative study on six marine sponge species collected along the French Mediterranean and Irish coasts for their TEs accumulation. Intra and inter-species variabilities were examined. Among the Mediterranean species, Cymbaxinella damicornis accumulates significantly more As and Cu than others sponge species; Chondrilla nucula more Ni and Mo and Acanthella acuta more Ag. Among Irish samples, Hymeniacidon perlevis showed higher accumulation properties for most of TEs in comparison to Halichondria panicea. Bioconcentration Factors were > 1 in all species for most of TEs. This study suggests that TEs bioaccumulation is most likely associated to differences in morphological features and/or to specific bacterial communities associated to different species. The determination of Pb isotope ratios revealed mainly natural Pb sources for Mediterranean and Kilkieran Bay's samples, and rather anthropogenic influence for Belfast samples. This study confirms that sponges represent a powerful tool for biomonitoring studies.

Behaviour of trace metals in the anoxic environment of Veraval harbour, India

The purpose of the present study is to investigate the behaviour of trace metals in anoxic environment. Water column of the harbour was found to be anoxic (DO <0.2mgl^-1) with high concentration of NH₄⁺-N (av. 459±21μmoll^-1) and H₂S (av.73±2.5μmoll^-1) irrespective of season and tide. High concentrations of Fe, Mn in bottom water indicated that Fe, Mn were diagenetically mobilized under the anoxic conditions prevailing in the harbour. In harbour sediments significant correlation of metals with TOC and TS indicated their diagenetic immobilization in anoxic environment. Fe was positively correlated with TS suggesting FeS formation in anoxic condition. TOC/TN ratio of sediments was higher (16±5.2) than the normal marine planktonic sediments suggesting an increased burden of terrestrial carbon in the harbour. A sediment core collected 10km away from the shore indicated build-up of trace metals in recent years, showing diagenetically upward movement of metals.

Seasonal effects to metallothionein responses to metal exposure in a naturalised population of Ruditapes philippinarum in a semi-enclosed estuarine environment

The Manila clam (Ruditapes philippinarum), an invasive species in Northern Europe, can be used as a bioindicator of metal pollution. Seasonal effects on metallothionein (MT) production have not been considered in this species at the northernmost extent of its European distribution. This study assesses the annual seasonal effects on MT and metal concentrations in R. philippinarum from Poole Harbour, UK. R. philippinarum were collected in winter, spring, summer, and autumn throughout 2015, and MT and metal concentrations, as well as biotic and abiotic variables, were quantified. During winter, linear regression analysis showed significant positive relationships between tissue metal and MT concentrations. However, during spring and summer, these relationships were mostly insignificant. MT concentrations during spring had significant positive relationships with tissue and whole weight. Significant positive relationships were also observed between MT and condition index, during summer. During spring and summer, biotic factors seem to override the role of MT as a detoxification mechanism for metal exposure in this species. This is probably due to an increase in MT concentration in spring caused by gametogenesis, associated with increased tissue weight as the gonads expand. A depletion of energy resources, or physical stressors such as heat, may be attributed to the reduced MT production in clams of poor body condition in summer. The evidence from this study suggests that MT may only be a useful biomarker of metal pollution during winter in R. philippinarum in the UK. This verifies the natural variability of MT in this species at high latitudes, and highlights the potential and limits to a widely available bioindicator of metal pollution.

Behavioural and biochemical alterations in Penaeus monodon post-larvae diet-exposed to inorganic mercury

Mercury is a metal naturally present in the environment with concentrations in aquatic systems increasing annually due to human activities. This represents a great concern mainly due to its high toxicity to organisms and consequences for human health. Most studies regarding the toxic effect of mercury have focussed on freshwater species using water as the exposure and uptake pathway. In contrast, the present study investigated the effects of dietary exposure of mercury to the marine crustacean Penaeus monodon post-larvae during 96 h to evaluate changes in behaviour (swimming activity and risk taken) and in biochemical biomarkers [acetylcholinesterase (AChE) and glutathione S-transferase (GST)]. Results showed a decrease in swimming activity with an increase in mercury exposure, but no changes were observed regarding the behavioural response 'risk taken'. Prawns from medium (0.56 μg g^-1) and high (1.18 μg g^-1) treatments had their GST activity reduced in relation to the beginning of experiment (time 0), while AChE activity was increased in the low (0.15 μg g^-1) treatment in relation to time 0. In the present study, behaviour analysis were clearer than biochemical biomarkers and results might indicate P. monodon populations from a mercury contaminated environment might be at risk, since the behavioural alterations observed increases the risk of predation.

Heavy metal distribution in organic and siliceous marine sponge tissues measured by square wave anodic stripping voltammetry

May sponge spicules represent a "tank" to accumulate heavy metals? In this study we test this hypothesis determining the distribution of Cd, Pb and Cu concentrations between organic and siliceous tissues in Antarctic Demospongia (Sphaerotylus antarcticus, Kirkpatrikia coulmani and Haliclona sp.) and in the Mediterranean species Petrosia ficiformis. Results show that although, in these sponges, spicules represent about 80% of the mass content, the accumulation of pollutant is lower in the spicules than in the corresponding organic fraction. The contribution of tissues to the total sponge content of Cd, Pb and Cu is respectively 99%, 82% and 97% for Antarctic sponges and 96%, 95% and 96% for P. ficiformis, similar in polar and temperate organisms. These results pave the way to a better understanding of the role of marine sponges in uptaking heavy metals and to their possible use as monitor of marine ecosystems, recommend by the Water Framework Directive.

Seasonal variation and annual trends of metals and metalloids in the blood of the Little Penguin (Eudyptula minor)

Little Penguins (Eudyptula minor) are high-trophic coastal feeders and are effective indicators of bioavailable pollutants in their foraging zones. Here, we present concentrations of metals and metalloids in blood of 157 Little Penguins, collected over three years and during three distinct seasons (breeding, moulting and non-breeding) at two locations: the urban St Kilda colony and the semi-rural colony at Phillip Island, Victoria, Australia. Penguin metal concentrations were foremostly influenced by location (St Kilda>Phillip Island for non-essential elements) and differed among years and seasons at both locations, reflecting differences in seasonal metal bioaccumulation or seasonal exposure through prey. Mean blood mercury concentrations showed an increasing annual trend and a negative correlation with flipper length at St Kilda. Notably, this study is the first to report on blood metal concentrations during the different stages of moult, showing the mechanism of non-essential metal mobilisation and detoxification.

The Little Penguin (Eudyptula minor) as an indicator of coastal trace metal pollution

Monitoring trace metal and metalloid concentrations in marine animals is important for their conservation and could also reliably reflect pollution levels in their marine ecosystems. Concentrations vary across tissue types, with implications for reliable monitoring. We sampled blood and moulted feathers of the Little Penguin (Eudyptula minor) from three distinct colonies, which are subject to varying levels of anthropogenic impact. Non-essential trace metal and metalloid concentrations in Little Penguins were clearly linked to the level of industrialisation adjacent to the respective foraging zones. This trend was more distinct in blood than in moulted feathers, although we found a clear correlation between blood and feathers for mercury, lead and iron. This study represents the first reported examination of trace metals and metalloids in the blood of any penguin species and demonstrates that this high trophic feeder is an effective bioindicator of coastal pollution.

Effects of organism preparation in metallothionein and metal analysis in marine invertebrates for biomonitoring marine pollution

Metallothionein (MT) is established as a potentially useful biomarker for monitoring aquatic pollution. This paper addresses widespread inconsistencies in storage conditions, tissue type selection and pre-treatment of samples before MT and metal analysis in biomarker studies. This variation hampers comparability and so the widespread implementation of this monitoring approach. Actively sampled Mytilus edulis in Southampton Water, UK were exposed to different storage temperatures, a variety of tissue types were analysed, and various pre-treatments of transportation on ice, transportation in seawater, depuration, and rapid dissection in the field were examined. Storage temperatures of -20 °C were found to be adequate for periods of at least ten weeks, as MT was not reduced by protein degradation compared with samples kept at -80 °C. Whole tissue and digestive gland concentrations of MT and metals were significantly positively correlated and directly relatable. MT in the digestive gland appeared to be more responsive to metals than in whole tissue, where it may be diluted, masking MT responses. However, longer study periods may suffer the effects of mass changes to the digestive gland, which alters MT concentration, and it may therefore be advisable to measure whole tissue. Depuration and transportation in seawater reduced both MT and metal concentrations in the digestive gland, and few correlations between MT and metals were identified for these treatments. It is therefore recommended that: i) samples are transported to the laboratory on ice and dissected as soon as possible thereafter, ii) depuration should not be used when examining MT response to metal exposure until further research clarifying its utility is reported, iii) either whole tissue or the digestive gland can be used to measure MT, though whole tissue may be preferable on long-term studies, and iv) organisms can be stored at -20 °C before analysis for up to ten weeks. These practices can be applied to future biomonitoring studies and will improve the comparability and repeatability of using MT as a biomarker.

Physicochemical parameters aid microbial community? A case study from marine recreational beaches, Southern India

A total of 176 (water and sediment) samples from 22 stations belonging to four different (urban, semi-urban, rural, and holy places) human habitations of Tamil Nadu beaches were collected and analyzed for physiochemical and microbial parameters during 2008-2009. Bacterial counts were two- to tenfold higher in sediments than in water due to strong bacterial aggregations by dynamic flocculation and rich organic content. The elevated bacterial communities during the monsoon explain rainfalls and several other wastes from inlands. Coliform counts drastically increased at holy and urban places due to pilgrimage and other ritual activities. Higher values of the pollution index (PI) ratio (>1) reveals, human fecal pollutions affect the water quality. The averaged PI ratio shows a substantial higher microbial contamination in holy places than in urban areas and the order of decreasing PI ratios observed were: holy places > urban areas > semi-urban areas > rural areas. Correlation and factor analysis proves microbial communities were not related to physicochemical parameters. Principal component analysis indicates 55.32 % of the total variance resulted from human/animal fecal matters and sewage contaminants whereas 19.95 % were related to organic contents and waste materials from the rivers. More than 80 % of the samples showed a higher fecal coliform and Streptococci by crossing the World Health Organization's permissible limits.

Limitations of metallothioneins in common cockles (Cerastoderma edule) and sponges (Haliclona oculata) as biomarkers of metal contamination in a semi-enclosed coastal area

Poole Harbour is typical of many heavily anthropologically impacted semi-enclosed estuarine coastal areas under pressure from metal pollution across the world. This study examined the physiological significance of metal burdens within that sensitive area, and assessed the potential use of metallothionein (MT) concentrations in two organisms: the common cockle (Cerastoderma edule) and the Mermaid's glove sponge (Haliclona oculata) for mapping the spatial extent of the biological response to metal contamination. A spectrophotometric method was applied for detection of MT in the bivalve, and for the first time to detect MT in sponges. The results show that while some metal concentrations in cockle and sponge tissues and in their surrounding environment (water and sediment) could be related to sources of metal contamination, MT values in the soft tissue of cockles and whole tissue of sponges are not. No relation could be found between MT in both cockles and sponges, and any of the tested metals (As, Cd, Cr, Cu, Pb, Hg, Ni, Ag, Sn, Zn). Furthermore, some of the lowest MT concentrations were detected in heavily polluted areas, indicating that MT concentrations in tested organisms are not exclusively associated with metal concentrations, as other environmental factors could affect induction of this protein. Organisms probably have a high tolerance to metal contamination and chronic exposure to a high level of contamination resulted in developing a variety of detoxification mechanisms. Results indicate that further study of metal stress in this type of ecosystem may need to examine other indicator species and/or apply a different biomonitoring technique.

Benthic macroalgae as biological indicators of heavy metal pollution in the marine environments: a biomonitoring approach for pollution assessment

Metal pollution in the marine coastline environment is an important topical issue in the context of ecological disturbance and climate change. Heavy metal contaminations (Cd, Cr, Cu, Mn, Ni, Pb and Zn) in seawater and surficial sediments, as well as macroalgal diversity, were determined in six different locations along the coast of the Gulf of Kutch in India. The marine coastline environment was found to be enriched with Cd and Zn in comparison to other metals. Significant (p ≤ 0.05) inter-elemental positive-correlations were observed between Fe-Mn, Fe-Cu, Fe-Cr, Fe-Zn, Cr-Cu, Cu-Mn, and Cd-Zn, as well as negative-correlations between Cd-Pb, Ni-Pb, and Zn-Pb. Though genus specific macroalgal responses to heavy metal accumulation were significant, species specific response was insignificant (p ≤ 0.05). The relative abundance of metals in macroalgae followed the order of Fe>Zn>Mn>Cu>Cd>Cr>Ni>Pb. The high uptake of metals in green algae (Ulva lactuca and Enteromorpha intestinalis) and brown algae (Padina gymnospora and Dictyota bartayresiana) suggested that these algae may be used as potential biomonitors for heavy metal pollution. Three pollution indicators, Contamination Factor (CF), Enrichment Factor (EF) and Geochemical Index (Igeo) were calculated to determine the degree of metal pollution in the marine coastline and the contribution of anthropogenic influence.

Biomonitoring of trace metal pollution using the bivalve molluscs, Villorita cyprinoides, from the Cochin backwaters

Trace metal concentrations in the muscle of the bivalve Villorita cyprinoides from the Cochin backwaters (southwest coast of India) were investigated during the monsoon, post-monsoon and pre-monsoon periods. The seasonal average ranges of metals (μg g(-1), dry weight) in the bivalve were as follows: Fe (18,532.44-28,267.05), Co (23.25-37.58), Ni (10.56-19.28), Cu (3.58-11.35), Zn (48.45-139.15), Cd (1.06-1.50) and Pb (3.05-4.35). The marginally elevated metal concentrations in bivalve muscles are probably related to high influx of metals as a result of pollution from the industries and agricultural fields with consequent increased bioavailability of metals to the bivalve. Evaluation of the risks to human health associated with consumption of the bivalves suggested that there is no health risk for moderate shellfish consumers. A regular and continuous biomonitoring program is recommended to establish V. cyprinoides as a bioindicator for assessing the effects of trace metal pollution and to identify future changes to conserve the "health" of this fragile ecosystem.