Transects of polycyclic aromatic hydrocarbons and organochlorine pesticides in an urban estuary using passive samplers.

Hydrophobic organic contaminants (HOCs) are tracers of anthropogenic impacts, which can negatively affect water quality. The relative importance of new emissions versus the remobilization of HOCs from legacy reservoirs is not well constrained. Polyethylene passive samplers were deployed in vertical profiles at four sites to determine the concentrations and gradients of atmospheric and freely dissolved polycyclic aromatic hydrocarbons (PAHs) and freely dissolved organochlorinated pesticides (OCPs) in Narragansett Bay, an urban estuary. The concentrations of the sum of 20 PAHs ranged from 4.3 to 240 ng/m3 in the air and 3.2-21 ng/L in the water column, dominated by phenanthrene and pyrene. OCP concentrations varied from below the detection limit to 150 ng/L in the water column. Common OCPs included α-hexachlorocyclohexane, hexachlorobenzene, and aldrin. Gradients displayed net deposition for PAHs, but equilibrium through the water column. Results from this study provided evidence that key OCPs displayed mostly similar concentrations (at or near equilibrium) in the water at both Conimicut Point and Block Island.

Land use and COVID-19 lockdowns influence debris composition and abundance in stormwater drains.

Stormwater drains act as a pathway for anthropogenic debris from land to sea, particularly in urbanised estuaries where impervious surfaces expedite the process. Debris type and abundance in stormwater drains may vary due to land use and human activity, and knowledge of this variation is necessary to manage the growing threat of debris. Surveys of stormwater debris can inform targeted reduction and remediation efforts by intercepting and identifying pollutants near their source. We surveyed replicate stormwater gross pollutant traps across four land use zones (city centre, shopping centre, transportation hub, industrial precinct) before and during COVID-19 measures to assess the effects of changing human activities. Gross pollutant traps were installed in 120 drains in Greater Melbourne, Australia, and citizen scientists trained by Tangaroa Blue Foundation weighed and classified debris at 6-week intervals between October 2019 and October 2020. Four survey cycles were conducted before lockdowns were implemented, then another four during lockdowns. COVID-19 lockdowns and patterns of debris type and abundance across land use revealed how changes in human activity might impact the flow of debris. Cigarette butts were the most abundant macro debris (>5 mm) item in every survey cycle, regardless of lockdowns. Industrial land use zones had the lowest macro debris counts but contained over 90 % of the micro debris (1-5 mm). The amount of total macro debris decreased during lockdowns, however the most abundant and problematic debris items such as cigarettes and single-use plastics did not decrease as much as might be expected from the concomitant reductions in human activity. Occupational health and safety items, such as masks and gloves, increased (144 %) during COVID-19 lockdowns. Micro debris counts did not change in industrial zones during lockdowns, suggesting that workplace interventions may be necessary to reduce this debris leakage. Tracing the pathway of debris from source to sea can inform reduction and long-term management strategies.

Modeling recreational fishing intensity in a complex urbanised estuary.

Urbanised estuaries, ports and harbours are often utilised for recreational purposes, notably recreational angling. Yet there has been little quantitative assessment of the footprint and intensity of these activities at scales suitable for spatial management. Urban and industrialised estuaries have previously been considered as having low conservation value, perhaps due to issues with contamination and disturbance. Studies in recent decades have demonstrated that many of these systems are still highly biodiverse and of high value to local residents. As a response, urbanised estuaries are now being considered by coastal spatial management initiatives, where assessments of recreational use in these areas can help avoid 'user-environmental' and 'user-user' conflict. The models of these activities need to be developed at a scale relevant to governments and regulatory authorities, but the few human-use models that do exist integrate fishing intensity to a regional or even continental scale; too large to capture the fine scale variation inherent in complex urban fisheries. Species Distribution Modeling (SDM) is a tool commonly used to assess drivers of species range, but can be applied to models of recreational fishing in complex environments, at a scale relevant to regulatory bodies. Using point-data from 573 visual surveys with recently developed Poisson point process models, we examine the recreational fishery in Australia's busiest estuarine port, Sydney Harbour. We demonstrate the utility of these models for understanding the distribution of boat and shore-based fishers, and the effects of a range of temporally static (geographical) and dynamic (weather) predictors on these distributions.

Microplastic and tire wear particle occurrence in fishes from an urban estuary: Influence of feeding characteristics on exposure risk.

The influence of feeding behavior and feeding ecology on microplastic occurrence in fishes in an urbanized estuary was studied by surveying microplastics in the digestive tracts (gut) of five fish species: the planktivorous Bay Anchovy and Atlantic Menhaden, the piscivore Spotted Seatrout, the benthivore Spot and the detritivore/benthivore Striped Mullet. Microplastics were found in 99% of fishes collected with an average of 27 microplastics per individual fish, 6 microplastics per gram of fish, and 21 microplastics per gram of gut, although exposure varied among species. Atlantic Menhaden possessed significantly more microplastic per fish weight than other species, which may be attributed to their regular ingestion of marine snow aggregates. Fibers were the most common type of microplastic in all fishes, and suspected tire wear particles were found in 14% of individuals across all five species, constituting the first evidence of tire wear particle consumption in field-collected organisms.

Metabolomic profiling for juvenile Chinook salmon exposed to contaminants of emerging concern.

Both targeted and non-targeted metabolomic analyses were conducted on juvenile ocean-type fall Chinook salmon (Oncorhynchus tshawytscha) residing in two estuaries receiving wastewater treatment plant (WWTP) effluent and one reference estuary. The data show that the metabolome patterns for fish from the two WWTP-receiving estuaries were more similar to each other compared to that for the reference site fish. Also, a comparison of the metabolome for fish from the reference site and fish from a hatchery upstream of one of the effluent-receiving estuaries indicated no differences, implying that residency for fish in the contaminated estuary resulted in major changes to the metabolome. Based on general health parameters including whole-body lipid content and condition factor, plus the availability of prey for these fish, we conclude that juvenile Chinook salmon in these contaminated estuaries may have been experiencing metabolic disruption without any overt signs of impairment. Additionally, a non-targeted analysis was performed on hatchery summer Chinook salmon from a laboratory study where fish were dosed for 32 days with feed containing 16 of the most common contaminants of emerging concern (CECs) detected in wild fish. In the laboratory experiment a relationship was observed between dose and the number of liver metabolites that were different between control and treatment fish. Laboratory fish were exposed to only 16 CECs, but are generally exposed to hundreds of these compounds in contaminated aquatic environments. These results have implications for the health of juvenile Chinook salmon and the likelihood of a successful life cycle when exposed to effluent-related chemicals.

Effect of neap-spring hydrodynamics on salt and suspended sediment transport in multi-branched urban estuaries.

Unique neap and spring tide hydrodynamic features were studied in the estuarine areas of multi-branched urban rivers in Tokyo, Japan. Intensive measurements of salinity, turbidity, dissolved oxygen, velocity, particulate organic matter (POM), and nutrients were conducted for 13h in five stations simultaneously on July 3 and July 11, 2017. Water sampling, analysis and calculations of salt and sediment transport were performed. Results showed that the Arakawa and Sumida Rivers follow the typical natural estuary hydrodynamics while Shakujii River followed a typical artificial urban estuary. Shakujii River upstream estuary had lower flow velocity during spring tide (-0.05 to 0.04m/s) than neap tide (-0.09 to 0.16m/s) because of the channel slope that does not allow the transit of water to upstream even during high tide. Shakujii River downstream estuary had hypoxic (DO<2mg/L) bottom depths during neap and spring tide. Sumida River and Shakujii River are adjacent yet the nutrient and POM had different nature. Shakujii River is highly influenced by freshwater from combined sewer systems carrying POM, nutrients and sediments. The freshwater was 54% (14,650m3) and 100% (28,671.1m3) by volume during neap and spring tide, respectively. The POM and nutrients in Sumida River is influenced by tidal processes and tributary rivers. SS was transported from Sumida to Shakujii River during flood phase of spring tide. Freshwater from Arakawa River flows to Sumida River during ebb tide. Salt (-0.066kg/m/s) and SS (-0.16 to -2.435kg/m/s) were retained in the estuaries which may lead to river deterioration and occurrence of scum, hypoxia and odor. The results of the study, particularly on Shakujii River, are significant and could serve as basis for water quality management in similar urban estuaries.

Characterization of dissolved organic matter in an urbanized estuary located in Northeastern Brazil.

The Sal River estuary, which is located in the state of Sergipe, Northeastern Brazil, stands out as an urban estuary, anthropogenically impacted by untreated and treated wastewater discharge. Synchronous fluorescence spectroscopy and measurement of dissolved organic carbon (DOC) were used for characterization of dissolved organic matter (DOM) in the estuarine water. Dissolved organic carbon concentrations ranged from 7.5 to 19.0 mg L-1 and, in general, the highest values were recorded during dry season. For both seasons (dry and rainy), DOC presented an inverse linear relationship with salinity, which indicates a conservative dilution of organic matter coming into the estuary. During rainy season, anthropogenic organic constituents and humic substances from land-based sources predominated in DOM composition, carried by river flow. Whereas during the dry season, it has been observed a significant increase of products generated by microbial degradation of anthropogenic organic matter. The relationships between fluorescence intensity and salinity suggest a conservative behavior during rainy season and a non-conservative behavior during dry season, with addition of fluorescent organic matter into the intermediate zone of the estuary. Photodegradation by action of sunlight caused a decrease in fluorescence intensity of humic and tryptophan-like constituents and the release of photoproducts, resulting in an increase in fluorescence intensity of protein-like constituents.

Quantification of heat shock protein 70 and acetylcholinesterase over a time course suggests environmental adaptation in a foundational molluscan species.

Waterways in urban areas often act as repositories for sewage, industrial waste, and environmental contaminants. In response, inhabitants of these watersheds undergo physiological adaptations specific to their respective environments. Effects of these stressors can be assayed by quantification of various well-documented biomarkers in sentinel species such as the Atlantic Ribbed mussel, Geukensia demissa, a native to the Bronx River Estuary, Bronx, NY, USA. Heat shock protein 70 (Hsp70) is a universally expressed biomarker for an array of environmental stressors including toxins and low dissolved oxygen. To better understand the mechanisms by which organisms tolerate their contaminated environments, we monitored the constitutive and heat shock-induced levels of two proteins: Hsp70 and acetylcholinesterase (AChE) in natural populations of G. demissa from differentially impacted sites: the Bronx River and Greenwich Cove estuaries. We show that G. demissa from the Bronx River exhibits a higher level of constitutive Hsp70, and launches a more rapid and robust heat shock response than does its Greenwich Cove counterpart. In addition, AChE levels are recovered more quickly in Bronx River mussels. Based on response pattern investigations from heat stress as well as constitutive expression, we suggest that the Hsp70/AChE chaperone/client relationship exemplifies the unique adaptive mechanisms utilized by organisms in order to tolerate environmentally impacted habitats. Results from this study offer important insights from an ecological perspective into the molecular and cellular basis of stress response and provide valuable information regarding adaptation to the increased demands of challenging environments.

Otolith microchemistry: Insights into bioavailable pollutants in a man-made, urban inlet.

Black bream (Acanthopagrus butcheri) were collected from an artificial inlet, Claisebrook Cove, Western Australia. Claisebrook Cove is adjacent to an historic contaminated site that was remediated during the 1990s. It was later identified as a priority area due to elevated levels of sediment contaminants including Zn, Cu, and Pb. Black bream were collected from this cove in 2005 and 2012 and their otoliths were analysed by laser ablation inductively coupled plasma mass spectrometry of the most recent growth zone. Levels of Zn and Mn, which are metabolically regulated, did not correlate with sediment contamination. However, reduction in sediment Cu levels over time coincided with reduced Cu otolith levels from 2005 to 2012. Results indicate that the elemental composition of the marginal edge of Black bream otoliths can identify bioavailable contaminants in an urban estuary and, with monitoring, can be utilized to establish long-term trends.

Statistical evaluation of biogeochemical variables affecting spatiotemporal distributions of multiple free metal ion concentrations in an urban estuary.

Free metal ion concentrations have been recognized as a better indicator of metal bioavailability in aquatic environments than total dissolved metal concentrations. However, our understanding of the determinants of free ion concentrations, especially in a metal mixture, is limited, due to underexplored techniques for measuring multiple free metal ions simultaneously. In this work, we performed statistical analyses on a large dataset containing repeated measurements of free ion concentrations of Cu, Zn, Pb, Ni, and Cd, the most commonly measured metals in seawater, at five inshore locations in Boston Harbor, previously collected using an in-situ equilibrium-based multi-metal free ion sampler, the 'Gellyfish'. We examined correlations among these five metals by season, and evaluated effects of 10 biogeochemical variables on free ion concentrations over time and location through multivariate regressions. We also explored potential clustering among the five metals through a principal component analysis. We found significant correlations among metals, with varying patterns over season. Our regression results suggest that instead of dissolved metals, pH, salinity, temperature and rainfall were the most significant determinants of free metal ion concentrations. For example, a one-unit decrease in pH was associated with a 2.2 (Cd) to 99 (Cu) times increase in free ion concentrations. This work is among the first to reveal key contributors to spatiotemporal variations in free ion concentrations, and demonstrated the usefulness of the Gellyfish sampler in routine sampling of free ions within metal mixtures and in generating data for statistical analyses.

Improving management support tools for reintroducing bivalve species (eastern oyster [Crassostrea virginica Gmelin]) in urban estuaries.

Successful reintroduction of "ecologically extinct" bivalve species into anthropogenically impaired urban estuaries is problematic when employing existing management tools used in estuaries where bivalves are present (GIS-based restoration models, expanding existing shellfish beds, placement of shell substrate, physical oceanographic parameters). A significant management challenge is appropriate site selection. We are proposing the inclusion of a biological parameter (evaluation of tissue histopathology) in an inexpensive and rapid site selection model to inform management decision making and identify sites with the greatest potential for reintroduction success. Use of biological biomarkers is not a new concept, but it is important that they be included in a multitiered management approach to bivalve reintroduction. This Case Study tested adult Eastern Oysters (Crassostrea virginica Gmelin) from locations that supported comparable short-term survival rates by evaluating growth and tissue health and/or disease. Biomarkers indicated oyster tissues at one site were normal, the female:male sex ratio was 50:50, and female oysters were in spawning condition. Conversely, oyster tissues at the second site exhibited multiple abnormalities, samples were 100% male, and the incidence of disease was high. Using the biomarker tool, we evaluated 4 additional sites where oysters exhibited short-term (1 year) survival. At 2 locations, we observed chronic health impacts that would preclude reintroduction, including samples from one site where a wild population was surviving. We also analyzed tissue and shell heavy metal contents. Soft tissue metal concentrations in Meadowlands samples were at the high range of scientific literature values, averaging 1.1% of total body weight, whereas tissue metal concentrations at the Keyport site were within acceptable ranges. Although initial survival and growth rates at both locations were comparable, site-specific urban stressors reduced oyster fitness at 1 of the 2 locations. We are proposing an Estuarine Reintroduction Site Selection Model, which includes a biological in situ parameter, to increase the probability of successfully managing a sustainable oyster reintroduction before commencing expensive large-scale restoration activities.