Chemical Contaminants In Sediments Research Articles

Mixtures of sediment chemical contaminants at freshwater sampling sites across Europe with different contaminant burdens

Extended chemical analyses of fluvial sediments were undertaken to establish the key pollutant pressures and mixtures present across nine European Union inland waterways. A wide range of chemical components and physical parameters were investigated including substances from the EU Priority List and Watch List. The data set was examined for key indicator compounds, however it was found that a wide range of pollution pressures were present in the different sediments including organic hydrocarbons, metal(loid)s, nutrients, polycyclic aromatic hydrocarbon (PAH), polychlorinated biphenyl (PCB) compounds, perfluoroalkyl and polyfluoroalkyl substances and pesticides, some of which exceeded regulatory guidance at different sampling points. The presence of such a wide range of compounds underpins the complex chemical composition of sediments that have acted as sinks for many decades absorbing contaminants from urban, industrial and agricultural sources. This dataset has been used to describe average overall toxicity of the sediments sampled, a calculation which was based on key components identified by Principal Component Analysis (PCA) and for those that had existing freshwater sediment regulatory values. A total of 33 components were used including PCBs, PAHs, metal(iod)s and pesticides. This analysis reflected the contamination of each site, with most indicating some level of toxicity during the sampling period. Watch List chemicals triclosan (TCS) and diclofenac (DIC) were also investigated; levels were relatively low, typically 10–100's ng L−1, however they were present at all sampling sites. The dataset is available as a resource for future chemical, and toxicological, sediment analysis comparisons.

Selection of Macroinvertebrate Indices and Metrics for Assessing Sediment Quality in the St. Lawrence River (QC, Canada)

This study aims to evaluate the anthropogenic pressure in the St. Lawrence River by assessing the relationships between composition and chemical contamination of sediments and macroinvertebrate community structure using a selection of indices and metrics. The aims of this study are to (i) determine the composition of macroinvertebrate community in sediments across a gradient of disturbance, (ii) select relevant macroinvertebrate indices and metrics for the assessment of sediment quality, (iii) investigate whether responses of selected indices and metrics differ across habitats and/or sediment quality classes, and finally, (iv) determine the thresholds for critical contaminants related to significant changes in the most relevant indices and metrics. Organic and inorganic contaminants as well as other sediment variables (sediment grain size, total organic carbon, nutrients, etc.) and macroinvertebrate assemblages were determined in 59 sites along the river. Fourteen macroinvertebrate indices and metrics, on the 264 initially selected, were shown to be the most effective to be used in bioassessment for the St. Lawrence River. However, the variation in macroinvertebrate indices and metrics remains strongly explained by habitat characteristics, such as sediment grain size or the level of nutrients. There is also an influence of metals and, to a lesser extent, organic contaminants such as petroleum hydrocarbons. The 14 selected indices and metrics are promising bioassessment tools that are easy to use and interpret in an environmental assessment of sediment quality in the St. Lawrence River.

Assessing anthropogenic pressure in the St. Lawrence River using traits of benthic macroinvertebrates

This study aims to evaluate the anthropogenic pressure in the St. Lawrence River by assessing the relationships between chemical contamination of sediments and benthic community structure with the trait-based approach. Organic and inorganic contaminants as well as other sediment variables (sediment grain size, total organic carbon, nutrients, etc.) and benthic invertebrate assemblages were determined in 59 sites along the river. Biological and ecological traits of taxa were coded, taking into account regional climate and ecosystem conditions. The aims of this study were to (1) describe the relationships between traits and macroinvertebrate taxa and identify homogeneous clusters of taxa with the same combinations of functional traits, (2) describe spatial patterns in traits of macroinvertebrates in the St. Lawrence River, (3) link trait-based metrics and site groups to sediment quality and (4) define a trait-based strategy for diagnosing the ecological quality of the St. Lawrence River. Seven groups of taxa sharing similar trait-category attributes were defined. Moreover, four groups of sites were identified using the ‘K-mean’ non-hierarchical clustering approach. The ‘IndVal’ method enabled us to specifically defined trait categories corresponding to site groups on the basis of their indicator value. The relative abundances of taxa from five functional groups significantly varied among site groups. For example, some indicator traits such as multivoltine cycle, long life span, fixed clutches, tegumental respiration, asexual reproduction, and collector/gatherer feeding habit were associated to the most heavily polluted sites located in the Montreal harbour which showed the highest sediment concentrations in Pb, Zn and Cu. Three trait-based pressure-specific models were built, based on the random forest approach, for respectively (1) heavy metals, (2) BPCs and PAHs, and (3) TBTs occurring in the environment. These models could be applied to assess sediment quality using macroinvertebrate assemblages in a large Canadian river.

Assessment of metal contamination, bioavailability, toxicity and bioaccumulation in extreme metallic environments (Iberian Pyrite Belt) using Corbicula fluminea

The Iberian Pyrite Belt (SW Iberian Peninsula) has intense mining activity. Currently, its fluvial networks receive extremely acid lixiviate residue discharges that are rich in sulphates and metals in solution (acid mine drainage, AMD) from abandoned mines. In the current study, the sediment and water quality were analysed in three different areas of the Odiel River to assess the risk associated with the metal content and its speciation and bioavailability. Furthermore, sediment contact bioassays were performed using the freshwater clam Corbicula fluminea to determine its adequacy as a biomonitoring tool in relation to theoretical risk indexes and regulatory thresholds. Reburial activity and mortality were used as the toxic responses of clams when exposed to contaminated sediment.The results showed coherence between the water and sediment chemical contamination for most of the metals. The reburial activity was correlated with the metal toxicity, but no clam mortality was registered. The bioaccumulation of the studied metals in the clam did not have a significant correlation with the bioavailable fraction of the metal content in the environment, which could be related to a potential different speciation in this singular environment. The bioaccumulation responses were negative for As, Cd and Zn in highly contaminated environments and were characterized as severe, considerable and low potential environmental risks, respectively. The results show that C. fluminea is a good biomonitor of Cu and Pb.

An assessment of chemical contaminants in sediments from the St. Thomas East End Reserves, St. Thomas, USVI

The St. Thomas East End Reserves or STEER is located on the southeastern end of the island of St. Thomas, USVI. The STEER contains extensive mangroves and seagrass beds, along with coral reefs, lagoons, and cays. Within the watershed, however, are a large active landfill, numerous marinas, resorts, various commercial activities, an EPA Superfund Site, and residential areas, all of which have the potential to contribute pollutants to the STEER. As part of a project to develop an integrated assessment for the STEER, 185 chemical contaminants were analyzed in sediments from 24 sites. Higher levels of chemical contaminants were found in Mangrove Lagoon and Benner Bay in the western portion of the study area. The concentrations of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), zinc, copper, lead, and mercury were above a NOAA Effects Range-Low (ERL) sediment quality guideline at one or more sites, indicating impacts may be present in more sensitive species or life stages. Copper at one site in Benner Bay was above a NOAA Effects Range-Median (ERM) guideline indicating effects on benthic organisms were likely. The antifoulant boat hull ingredient tributyltin (TBT) was found at the third highest concentration in the history of NOAA's National Status and Trends (NS&T) Program, which monitors the nation's coastal and estuarine waters for chemical contaminants and bioeffects. The results from this project will provide resource managers with key information needed to make effective decisions affecting coral reef ecosystem health and gauge the efficacy of restoration activities.

Monitoring effects of remediation on natural sediment recovery in Sydney Harbour, Nova Scotia

Chemical contaminants were assessed in Sydney Harbour, Nova Scotia during pre-remediation (baseline) and 3years of remediation of a former coking and steel facility after nearly a century of operation and historical pollution into the Sydney Tar Ponds (STP). Concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, metals, and inorganic parameters measured in sediments and total suspended solids in seawater indicate that the overall spatial distribution pattern of historical contaminants remains unchanged, although at much lower concentrations than previously reported due to natural sediment recovery, despite remediation activities. Measured sediment deposition rates in bottom-moored traps during baseline were low (0.4-0.8cm year(-1)), but during dredging operations required for construction of new port facilities in the inner Sydney Harbour, sedimentation rates were equivalent to 26-128cm year(-1). Measurements of sediment chemical contaminants confirmed that natural recovery rates of Sydney Harbour sediments were in broad agreement with predicted concentrations, or in some cases, lower than originally predicted despite remediation activities at the STP site. Overall, most measured contaminants in sediments showed little temporal variability (4years), except for the detection of significant increases in total PAH concentrations during the onset of remediation monitoring compared to baseline. This slight increase represents only a short-term interruption in the overall natural recovery of sediments in Sydney Harbour, which were enhanced due to the positive impacts of large-scale dredging of less contaminated outer harbor sediments which were discharged into a confined disposal area located in the inner harbor.

Characterization of organic chemical contaminants in sediments from Jobos Bay, Puerto Rico

Jobos Bay, located on the southeastern coast of Puerto Rico, contains a variety of habitats including mangroves, seagrass meadows, and coral reefs. The watershed surrounding the bay includes a number of towns, agricultural areas, and the Jobos Bay National Estuarine Research Reserve (NERR). Jobos Bay and the surrounding watershed are part of a Conservation Effects Assessment Project (CEAP), involving the Jobos Bay NERR, the US Department of Agriculture, and the National Oceanic and Atmospheric Administration (NOAA) to assess the benefits of agricultural best management practices (BMPs) on the terrestrial and marine environments. As part of the Jobos Bay CEAP, NOAA collected sediment samples in May 2008 to characterize over 130 organic chemical contaminants. This paper presents the results of the organic contaminant analysis. The organic contaminants detected in the sediments included polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, and the pesticide DDT. PAHs at one site in the inner bay near a boat yard were significantly elevated; however, all organic contaminant classes measured were below NOAA sediment quality guidelines that would have indicated that impacts were likely. The results of this work provide an important baseline assessment of the marine environment that will assist in understanding the benefits of implementing BMPs on water quality in Jobos Bay.

Ecological Assessment of a Marine Coastal Area Affected by a Power Plant Water Discharge (Brindisi, Adriatic Sea)

Coastal ecosystems are subjected to multiple stresses, from physical disturbance to chemical contamination related to the local anthropogenic activities. The recent European directives and Italian laws recommend that the assessment of the ecological quality of costal seawater should be based on an integrated approach, taking into account the ecological complexity of the systems and highlighting the potential sources of impact. Here, we present the results of an environmental study carried out in the marine coastal area affected by the sea discharge of a Combined Cycle Power Plant (Torre Cavallo, Brindisi) and characterized by the presence of a Posidonia oceanica meadow. The study focused on the concentration of chemical contaminants in sediments, coupled with the study of quali-quantitative determinations of biological benthic communities meio- and macrozoobenthos). Data were integrated with data of phenology and lepidochronology of P. oceanica, as well as the concentrations of trace elements in leaves and rhizomes, in order to identify potential sources of stress. Results suggested a good status of health of the coastal marine ecosystem.

Evaluation of potential relationships between chemical contaminants in sediments and aquatic organisms from the lower Passaic River, New Jersey, USA

The lower Passaic River, New Jersey, USA, a tidal tributary to Newark Bay and part of the New York and New Jersey Harbor Estuary, is contaminated with a variety of persistent organic pollutants (POPs) due to nearly two centuries of heavy industrialization and urbanization. Resident aquatic organisms are exposed to, and can bioaccumulate, a variety of chemical contaminants from sediments, water and other organisms. In the present study, the relationships between selected POPs detected in both surface sediments and aquatic organisms are examined statistically along with the efficacy of using empirical biota-sediment accumulation factors (BSAFs) to describe such relationships. Regression analyses were conducted on synoptic surface sediment POP data (0 to 15 cm in depth) and whole-body tissue POP data for three prominent organisms that reside in the river and which are important components of the food web: mummichog (Fundulus heteroclitus), blue crab (Callinectes sapidus), and white perch (Morone americana). Per the equilibrium partitioning theory on which the BSAF model is based, surface sediment data were normalized to total organic carbon and tissue data were normalized to lipid content for each organism. Normalized surface sediment concentrations were generally poorly correlated with normalized biota tissue concentrations. The BSAF model was not found to be a reliable means to predict concentrations of POPs in select lower Passaic River organisms, using surface sediment chemistry data.

Sediment Toxicity of Industrialized Coastal Areas of Korea Using Bioluminescent Marine Bacteria

The quality of marine sediments from the industrialized coastal areas of Korea (Ulsan Bay, Masan Bay, and artificial Lake Shihwa) was investigated using a bacterial bioluminescence toxicity test. Sediment toxicity results were compared with the levels of chemical contamination (trace metals, organic wastewater markers, acid volatile sulfides, total organic carbon). Effective concentration 50% (EC50) of sediments ranged from 0.014 to 1.126 mg/mL, which is comparable to or lower than values in contaminated lakes, rivers, and marine sediments of other countries. Sediment reference index (SRI) ranged from 13 to 1044, based on the EC50 of the negative control sample. Mean average SRI values in Masan Bay and Lake Shihwa were approximately 8 and 9 times as high as that in Ulsan Bay, indicating higher sediment toxicity and greater contamination in the two former regions. Sediment toxicity were strongly associated with the concentrations of some chemicals, suggesting that this test may be useful for determining potential chemical contamination in sediments.

Growth and condition of 0-group European flounder, Platichthys flesus as indicator of estuarine habitat quality

The purpose of this present study was to use the growth rates, RNA–DNA ratio and morphometric (Fulton’s K) condition indices measured on 0-group juveniles European flounder, as a means of comparing the quality of estuarine nursery habitats. The Seine estuary, heavily impacted by manmade modifications and one of the most contaminated in Europe, was compared to two smaller estuaries considered as clean (low domestic, agricultural and industrial effluents). Indicators of human disturbance (sediment chemical contaminants) as well as biotic data (macrobenthos abundances) were used to establish between-site differences in environmental quality. The abundance of macrobenthos (potential preys for juvenile) was high and not significantly different among the three estuaries confirming the important role played by estuaries as feeding grounds. Sediment metal concentrations (Cd, Cr, Cu, Pb, Zn) were significantly higher in the Seine than in the Canche and Authie estuaries. Otolith growth was closely related to somatic fish growth, and we used daily otolith increments from the previous 10 days before capture as an indicator of 0-group flounder recent growth (RG). RG did not vary significantly among flounders from the Canche and Authie estuaries and individuals from the Seine had slower RG. RNA–DNA ratio and K values were also significantly lower in individuals from the Seine compared to those of the Authie or the Canche. Pollution (e.g. metal contaminants) is the most likely cause of growth and condition differences among estuaries. The results of this study suggest that habitat-specific fish growth and condition are useful proxies for habitat quality since they integrate the effect of multiple environmental factors.

Comparing fixed-point and probabilistic sampling designs for monitoring the marine ecosystem near McMurdo Station, Ross Sea, Antarctica

AbstractFixed-point and probabilistic sampling designs were compared to investigate which design best detected known contamination gradients in the marine ecosystem adjacent to McMurdo Station, Antarctica. The fixed-point sampling design included transects along historical contamination and physical disturbance gradients. The probabilistic sampling design used randomly selected hexagons spaced at 50 m intervals. In both designs, 15 stations were sampled over a small area (~1 km2) that extended from Winter Quarters Bay to Cape Armitage. Sediment quality triad components (sediment chemical contaminants, sediment toxicity, and a benthic index of biotic integrity) were measured to indicate chemical, toxicological, and biological effects. There were higher correlations between sediment quality triad components for the fixed-point sampling design than for the probabilistic design. The fixed-point design was better at detecting the intensity of alteration because disturbance of the marine ecosystem at McMurdo Station is localized within a small area. Based on these results, a limited fixed-point design with nine stations detected no significant change in macrofaunal community structure over a four year period from 2000–2004. However, the macrofaunal assemblages present in the contaminated portions of Winter Quarters Bay are indicative of a disturbed benthic community that has been subject to organic enrichment and toxic chemical exposure.

Growth and condition indices in juvenile sole Solea solea measured to assess the quality of essential fish habitat

We used growth rates (estimated from otolith microstructure), morphometric (Fulton's K condition index) and lipid (triacylglycerols:sterols ratio, TAG:ST) condition indices measured on 0-group juveniles of common sole, to compare the habitat quality of 7 nursery grounds with differing levels of anthropogenic pressure. Along the French coast of the Southern Bight of the North Sea and the Eastern English Channel, we compared 2 sites located in intensively developed and industrialised harbour areas (Dunkerque and Calais), 1 site in a medium and less industrialised harbour (Boulogne), 1 site near a large and polluted estuary (Seine) and 3 other sites located near small estuaries less subject to human pressure (Canche, Authie and Somme). Indicators of human disturbance as well as hydrological and biotic data were used to establish between-site differences in environmental quality. Our results indicate consistent differences in the growth and condition indices of 0-group sole among the 7 sites. Sole had the slowest growth (mean G = 0.54 mm d–1) and lowest condition indices (mean K = 1.07; TAG:ST = 0.32) at Dunkerque and Calais and the fastest growth (mean G = 0.70 mm d–1) and highest condition indices (mean K = 1.19; TAG:ST = 2.18) at the Authie, Canche and Somme estuaries. The indices measured in this study correlated well with anthropogenic disturbance and may provide a useful tool to assess habitat quality. Sites with highest sediment chemical contaminants had the lowest habitat quality and, through growth and lipid-storage limitation, could dramatically lower over-winter survival of the juveniles living in these nursery grounds

Environmental Consequences of Water Pumped from Greater New Orleans Following Hurricane Katrina: Chemical, Toxicological, and Infaunal Analysis

The U.S. Army Engineer Research and Development Center Environmental Laboratory, Vicksburg, MS, conducted a study to determine the extent to which Hurricane Katrina floodwaters in the New Orleans, Louisiana area may have had impacts on wildlife habitat and other biological resources in surrounding areas. These studies were conducted as part of the Interagency Performance Evaluation Taskforce, an investigation of environmental impacts originating from the failure of the hurricane protection system during Hurricane Katrina. This paper presents data regarding the effects of pumped floodwaters on sediment chemistry, toxicity, and benthic invertebrate assemblages near pumping stations that discharged floodwaters into marshes near Chalmette and Violet, Louisiana. Chemical contamination of sediments was observed and varied among sample locations (e.g., outfall locations, wastewater treatment plant, canals, and wetlands); however, trends in the chemistry data were not always consistent with bioassay results. A comparison of the sediment chemistry data from this study with three other studies reporting concentrations of chemicals in sediments within the city of New Orleans suggested that sediments and associated contaminants present within the levees were not pumped into the marsh in appreciable quantities.

Multi-lag cluster designs for estimating the semivariogram for sediments affected by effluent discharges offshore in San Diego

Maps are useful tools for understanding, managing, and protecting the marine environment, yet few useful and statistically defensible maps of environmental quality and aquatic resources have been developed in near-coastal regions. Current environmental management efforts, such as ocean monitoring by sewage dischargers, routinely sample areas of potential impact using sparse sampling grids. Heterogeneous oceanic conditions often make extrapolation from these grids to non-sampled locations questionable. Although rarely applied in coastal monitoring, kriging offers a more rigorous statistical approach to mapping and allows confidence intervals to be calculated for predictions. Its usefulness relies on accurate models of the spatial variability through estimating the semivariogram. Many optimal designs for estimating the semivariogram have been proposed, but these designs are often difficult to implement in practice. In this paper, we present simple design strategies for augmenting existing monitoring designs with the goal of estimating the semivariogram. In particular, we investigate a multi-lag cluster design strategy, where clusters of sites, spaced at various lag distances, are placed around fixed stations on an existing sampling grid. We find that these multi-lag cluster designs provide improved accuracy in estimating the parameters of the semivariogram. Based on simulation study findings, we apply a multi-lag cluster enhancement to the monitoring grid for the City of San Diego’s Point Loma Wastewater Treatment Plant as part of a special study to map chemical contaminants in sediments around its sewage outfall.

Sediment chemical contamination of a shallow water area close to the industrial zone of Porto Marghera (Venice Lagoon, Italy)

The industrial zone of Porto Marghera is one the most important “contaminated sites of national interest” (SIN) in Italy, being identified as an area of high environmental risk. The site includes a wide shallow water area of the Venice Lagoon extending toward the city of Venice, which was investigated in order to acquire information on the pollutant level and distribution. Grain-size, heavy metal, nutrient, and organic micropollutant concentrations were determined in the surface sediment layers (0–5 and 5–10 cm depths) of 51 sites. A generally low contamination was found, except for Hg concentration, which increases the toxicological risk in most of the sites of the area, according to the results of a comparison with Sediment Quality Guidelines. A heavy pollution fingerprint (Cd, Cu, Hg, Pb, and Zn up to 15.2, 257, 11.9, 248, and 3010 mg/kg d.w., respectively) was instead found near the Tresse Island, which is ascribed to the spill of pollutants from the contaminated sediment disposed therein. Grain-size and heavy metal profiles down to a depth of 40 cm in eight selected sites, finally show a probable decrease of the pollution affecting the area in recent years.

Relationships Between Toxicity and Concentrations of Chemical Contaminants in Sediments from Sydney Harbour, Australia, and Vicinity

Correlation analyses between measures of toxicity and concentrations of chemical contaminants were conducted for 103 surficial sediments from Sydney Harbour, Australia, and vicinity. Toxicity tests consisted of amphipod survival and reburial tests of whole sediments (Corophium colo), sea urchin fertilisation and larval development tests of pore waters (Heliocidaris tuberculata) and microbial bioluminescence (Microtox) tests of solvent extracts and pore waters. Toxicity in most tests correlated with concentrations of metallic contaminants, in particular, zinc, lead and copper. Organic contaminants did not correlate as significantly with toxicity. However, Heliocidaris tuberculata showed relationships with organochlorine compounds in samples with low to moderate metals contamination. Toxicity in the Microtox solvent extract test appeared to be primarily influenced by the presence of sulfur. This study has no precedent in Australia and the results support the validity of using local indigenous species in toxicity tests of field-collected sediments. This toxicity/chemistry dataset may be used in evaluations of sediment quality guidelines recently introduced to Australia.

Ecosystem Responses to Extreme Natural Events: Impacts of Three Sequential Hurricanes in Fall 1999 on Sediment Quality and Condition of Benthic Fauna in the Neuse River Estuary, North Carolina

A study was conducted in November 1999 to assess sediment quality and condition of benthic fauna in the Neuse River Estuary (NRE), North Carolina, USA, following the passage of three Atlantic hurricanes during the two months prior. Samples for analysis of macroinfauna (>0.5 mm sieve size), chemical contamination of sediments, and other abiotic environmental variables (salinity, dissolved oxygen, pH, depth, sediment granulometry) were collected at 20 sites from the mouth of the Neuse River at Pamlico Sound to approximately 90 km upstream. Results were compared to those obtained from the same area in July 1998 using similar protocols. Depressed salinity, caused by extreme rainfall and associated high freshwater flow, persisted throughout much of the estuary, which had experienced periods of water-column stratification and hypoxia of underlying waters. Fifteen of the 20 sites, representing 299 km2 (76% of the survey area), also showed signs of benthic stress based on a multi-metric benthic index of biotic integrity (B-IBI). Benthic impacts included reductions in the abundance, diversity, and numbers of species and shifts in taxonomic composition, with a notable increase in dominance of the opportunistic polychaete Mediomastus ambiseta as other former dominant species declined. There was no significant increase in the extent of chemical contamination compared to pre-hurricane conditions. Storm-related reductions in dissolved oxygen and salinity were the more likely causes of the observed benthic impacts, though it was not possible, based on these results, to separate storm effects from seasonal changes in the benthos and annual episodes of summer anoxia and hypoxia.

Linkages between tidal creek ecosystems and the landscape and demographic attributes of their watersheds

Twenty-three headwater tidal creeks draining watersheds representative of forested, suburban, urban, and industrial land cover were sampled along the South Carolina coast from 1994 to 2002 to: (1) evaluate the degree to which impervious land cover is an integrative watershed-scale indicator of stress; (2) synthesize and integrate the available data on linkages between land cover and tidal creek environmental quality into a conceptual model of the responses of tidal creeks to human development; and (3) use the model to develop recommendations for conserving and restoring tidal creek ecosystems. The following parameters were evaluated: human population density, land use, impervious cover, creek physical characteristics, water quality, sediment chemical contamination and grain size characteristics, benthic chlorophyll a levels, porewater ammonia concentration, fecal coliform concentration, and macrobenthic and nekton population and community characteristics. The conceptual model was developed and used to identify the linkages among watershed-scale stressors, physical and chemical exposures, and biological responses of tidal creeks to human development at the watershed scale. This model provides a visual representation of the manner in which human population growth is linked to changes in the physiochemical environment and ultimately the nursery habitat function of tidal creeks and the safety of seafood harvested from headwater tidal creeks. The ultimate stressor on the tidal creek ecosystem is the human population density in the watershed and associated increases in the amount of impervious land cover. Measurable adverse changes in the physical and chemical environment were observed when the impervious cover exceeded 10–20% including altered hydrography, changes in salinity variance, altered sediment characteristics, increased chemical contaminants, and increased fecal coliform loadings. Living resources responded when impervious cover exceeded 20–30%. The impacts on the living resources included reduced abundance of stress-sensitive macrobenthic taxa, reduced abundance of commercially and recreationally important shrimp, and altered food webs. Headwater tidal creeks appear to provide early warning of ensuing harm to larger tidal creeks, tidal rivers and estuaries, and the amount of impervious cover in a watershed appears to be an integrative measure of the adverse human alterations of the landscape. Through education and community involvement, a conservation ethic may be fostered that encourages the permanent protection of lands for the services they provide.

Cytochrome P4501A expression, chemical contaminants and histopathology in roach, goby and sturgeon and chemical contaminants in sediments from the Caspian Sea, Lake Balkhash and the Ily River Delta, Kazakhstan

Roach, goby and sturgeon were examined for cytochrome P4501A (CYP1A) expression and histopathology, in relation to contaminant burdens in fish and sediment. Gradients of induction of CYP1A were observed. Roach from the Ural and Ily River Deltas and roach and goby from the two stations nearest the Caspian Sea oil fields displayed higher levels of CYP1A expression in several organs than was observed in fish from further offshore. Great sturgeon and Russian sturgeon showed higher levels of CYP1A expression than was seen in starred sturgeon and gobies in the Ural delta. No fish showed evidence of contaminant-related histopathologies in the organs examined, despite the elevated CYP1A levels. Low levels of polychlorinated biphenyls and elevated levels of inshore and riverine petroleum hydrocarbons from these habitats suggest that this ongoing hydrocarbon exposure, and that from natural sources and long-term oil exploration on the Northeastern Caspian shore, contributed to the CYP1A induction observed.