Coastal Estuarine Systems Research Articles

EstuarySAT Database Development of Harmonized Remote Sensing and Water Quality Data for Tidal and Estuarine Systems.

Researchers and environmental managers need big datasets spanning long time periods to accurately assess current and historical water quality conditions in fresh and estuarine waters. Using remote sensing data, we can survey many water bodies simultaneously and evaluate water quality conditions with greater frequency. The combination of existing and historical water quality data with remote sensing imagery into a unified database allows researchers to improve remote sensing algorithms and improves understanding of mechanisms causing blooms. We report on the development of a water quality database "EstuarySAT" which combines data from the Sentinel-2 multi-spectral instrument (MSI) remote sensing platform and water quality data throughout the coastal USA. EstuarySAT builds upon an existing database and set of methods developed by the creators of AquaSat, whose region of interest is primarily larger freshwater lakes in the USA. Following the same basic methods, EstuarySAT utilizes open-source tools: R v. 3.24+ (statistical software), Python (dynamic programming environment), and Google Earth Engine (GEE) to develop a combined water quality data and remote sensing imagery database (EstuarySAT) for smaller coastal estuarine and freshwater tidal riverine systems. EstuarySAT fills a data gap that exists between freshwater and estuarine water bodies. We are able to evaluate smaller systems due to the higher spatial resolution of Sentinel-2 (10 m pixel image resolution) vs. the Landsat platform used by AquaSat (30 m pixel resolution). Sentinel-2 also has a more frequent revisit (overpass) schedule of every 5 to 10 days vs. Landsat 7 which is every 17 days. EstuarySAT incorporates publicly available water quality data from 23 individual water quality data sources spanning 1984-2021 and spatially matches them with Sentinel-2 imagery from 2015-2021. EstuarySAT currently contains 299,851 matched observations distributed across the coastal USA. EstuarySAT's primary focus is on collecting chlorophyll data; however, it also contains other ancillary water quality data, including temperature, salinity, pH, dissolved oxygen, dissolved organic carbon, and turbidity (where available). As compared to other ocean color databases used for developing predictive chlorophyll algorithms, this coastal database contains spectral profiles more typical of CDOM-dominated systems. This database can assist researchers and managers in evaluating algal bloom causes and predicting the occurrence of future blooms.

Simulation of encounter rates between zooplankton organisms and microplastics in a tropical estuary.

Coastal estuarine systems may hold a large number of microplastic particles, which predators often mistake for prey. This study estimated the encounter rates between microplastics (alleged prey) and zooplankton having different feeding modes, trophic positions, swimming velocities, and perception distances, under calm and turbulent conditions, and during two seasons. Surface water samples were taken at 10/12 sites of the Sontecomapan lagoon, southern Gulf of Mexico, to quantify microplastic concentration. Zooplankton organisms considered were copepods, chaetognaths, and luciferids, common organisms in the lagoon. In June, at surface waters and during calm conditions, mean encounter rates were 1.5, 2450, and 980 particles per individual per hour, that is, for copepods, chaetognaths, and luciferids, respectively. When the wind blows (0.8 m s-1) encounter rates were 1.2, 1.4, and 2.6 times higher than in calm conditions. In October, mean encounter rates under calm conditions were 0.2, 355, and 142 particles per individual per hour, for copepods, chaetognaths, and luciferids; these values increase 1.3, 1.6, and 3.3 times when the wind blows (1.12 m s-1). The major number of encounters in June was due to a higher concentration of microplastics, despite the lower turbulent velocity. Regarding their trophic position, we propose that secondary consumers (chaetognaths and luciferids) are more affected because they could eat microplastics via contaminated prey or accidentally ingest them owing to confusion in the motion signals, especially under turbulent conditions. Another consequence of encounters could be the entanglement of microplastics in the body of the animals, especially in those with complex morphology, such as crustaceans. Encounters between zooplankton and microplastics do not always result in ingestion or entanglement, but the encounters are the first step in the case of occurrence.

How does buoyancy behavior impact microplastic transport in an estuarine environment?

Much is still unknown about the transport behavior of microplastic pollutants within the marine environment, particularly smaller scale coastal systems such as estuaries. Through the use of a Lagrangian particle-tracking model coupled with a validated 3D hydrodynamic model, we examined the transport, pathway and ultimate fate of microplastic particles, both in an idealized estuary and Galveston Bay, Texas, USA. Emphasis was placed on differences based on settling behavior (neutrally versus negatively buoyant), use of random walk for diffusion processes, and release location. For Galveston Bay, settling behavior had a noteworthy impact on both the transport pathway of microplastic particles, as well as overall time spent within the bay. Particles with negative buoyancy were retained approximately seven times longer than those with neutral buoyancy. Negatively buoyant particles also showed a tendency to be dispersed eastward to Trinity Bay through the bottom baroclinic flow, while neutrally buoyant particles took a more direct route along the ship channel to the mouth of the bay. Idealized model simulations suggest impact of settling depends on the vertical mixing strength. For a system with stronger tidal mixing, negatively buoyant particles with small settling velocities may still behave similarly to neutrally buoyant particles, and differences only become apparent for particles that sink rather quickly (> 10 m d−1). Future sea-level rise or channel deepening tends to flush out neutrally buoyant particles more quickly, while increasing the retention time for negatively buoyant particles. Our results suggest that plastics within estuaries could show substantially different behavior depending on their buoyancy characteristics, highlighting a need to quantify specific settling velocities of plastic pollutants entering the coastal estuarine system.

The impact of anthropogenic pollutants on the distribution of a marine top predator within a coastal estuarine system.

Due to anthropogenic pressures, estuarine systems are among the most broadly impacted areas for marine top predator species. Given this, it is crucial to study the interaction between the vulnerable marine species that inhabit these regions with environmental and anthropogenic variables. This study aims to determine whether nutrient pollution is related to the presence of bottlenose dolphins in a coastal environment. Using a multi-year dataset and GAMs, we studied the relationship between marine pollutants and the presence of bottlenose dolphins in this highly impacted coastal marine environment. We observed that urban fertilizers were linked to the spatial distribution of bottlenose dolphins. There was a higher presence of bottlenose dolphins in areas with high levels of phosphoric acid. In contrast, at higher concentrations of nitrate, the presence of bottlenose dolphins decreased.

Documenting the duration and chlorophyll pigments of an allochthonous Karenia brevis bloom in the Loxahatchee River Estuary (LRE), Florida

In Fall 2017 a large bloom of the toxic dinoflagellate Karenia brevis developed in the Gulf of Mexico. After persisting for months, in Fall 2018 wind and water circulation patterns drove K. brevis towards the east coast of Florida. On September 29, 2018 Palm Beach County, FL beaches were closed due to respiratory and gastrointestinal issues associated with brevotoxins, and effects of brevotoxins were reported from within estuarine segments of the Loxahatchee River Estuary (LRE). This was the first apparent report of a K. brevis bloom impacting inshore portions of the LRE prompting us to question the longevity of K. brevis within a relatively shallow, well-flushed coastal-estuarine system. Within 3 days (October 1, 2018) of the first reported effects of toxins, K. brevis reached over one million cells/L and chlorophyll-a concentrations peaked at 13 µg L−1. Within 11 days (October 9, 2018) both K. brevis and chlorophyll pigment concentrations significantly (p-perm ≤ 0.05) dropped to an average of ≤ 30,000 cells L−1 and < 4 µg L−1 chlorophyll-a, indicating that the bloom had diminished. Using distance-based linear modeling (DistLM) K. brevis abundance alone explained 66% of the variation in a multivariate measure of chlorophylls (driven by carotenoids and chlorophyll-c pigment concentrations), supporting a K. brevis dominated bloom. Following the K. brevis bloom, additional HAB species K. mikimotoi and Pseudo-nitzschia spp singularly explained 6% of the variations in the multivariate measure of chlorophylls. The low explanatory power of individual HAB species, including K. brevis (≤ 0%), signifies the recovery of the phytoplankton population, where non-HAB species likely contributed to the variability in the multivariate measure of chlorophylls and overall chlorophyll-a concentrations (average of 2 µg L−1 during non-bloom conditions). Finally, we evaluated ambient and historical water quality data to assess how these parameters changed before, during, and after the 2018 K. brevis bloom. Temperature, salinity, and nutrients in the LRE were comparable to reports of other K. brevis bloom events along the west coast of Florida. Reduced ammonia-nitrogen (NH3-N) concentrations and increased tidal amplitude coincided with the end of the bloom in 2018. More work is needed to understand the specific mechanisms constraining K. brevis blooms in tidal estuaries. We suggest that future research focus on water residence times along with nutrient availability in controlling allochthonous HABs in lotic and tidally flushed estuaries. Also, we anticipate this work may stimulate additional efforts to characterize HABs using in situ observations coupled with multivariate measures of chlorophylls, though we recognize much work remains to fully define the value of this approach.

Ingestion of plastic fragments by the Guri sea catfish Genidens genidens (Cuvier, 1829) in a subtropical coastal estuarine system.

One of the most recognized anthropogenic impacts in marine environments is solid waste pollution, especially plastic, which can be ingested by fish, thus interfering with their health. In this context, the aim of this study is to describe the ingestion of plastic fragments and to identify the possible effect of this contamination in the condition factor of Genidens genidens in the Laguna Estuarine System. The stomach contents of 92 G. genidens (26 juveniles and 66 adults) were analyzed. The Index of Relative Importance was performed to identify the contribution of each prey item. Condition factor (CF) was used to analyze the effect of plastic ingestion on the fish's body condition (by comparing individuals in the same ontogenetic phase). For the juveniles, eight items were observed, the most important of which were Penaeidae, followed by Portunidae and plastic. For the adults, 12 items were observed, the most important of which were Penaeidae, Portunidae, Polychaeta, and plastic. The analysis of CF demonstrated higher values for individuals without plastic in the stomach, which indicated a better health condition. The CF of a fish may be affected by variations in the physiological condition, environmental stresses, and nutritional and biological variations, and could be used to compare the body condition or health of a fish species. The ingestion of plastic could significantly influence the worst body condition of the individuals that were analyzed in the present study. The plastic pollution in marine coastal waters is associated with the appropriate waste management levels.

An operational coastal forecasting tool for performing ensemble modeling

An automated coastal estuarine modeling system, termed Multistage, is created in the ADCIRC hydrodynamic model. The software development was motivated by the need for reducing the simulation wall-clock time to increase the scalability of ADCIRC for ensemble modeling. Multistage makes use of a one-way nesting technique as an alternative to the continuous single-domain approach. Hydrodynamic predictions, such as storm surge and waves, are made for a targeted coastal region in a two-stage scheme consisting of a large-scale coarse mesh simulation and a small-scale fine mesh simulation. The nesting technique is adjusted for accurate and efficient coastal estuarine modeling with careful considerations. We propose and successfully test a method for the coarse mesh extending onshore rather than the common practice of extending the fine mesh offshore. Repetitive ensemble computations are allowed over both the coarse mesh and the fine mesh in an efficient time frame. Modeling preparations and processes are scripted to eliminate the additional efforts needed for applying this model nesting technique. The tool is tested on two coastal estuarine systems, and its performance is compared with the conventional single-domain method and observational data. By implementing Multistage, forecast runtimes are reduced by 50% to more than 80% using the same model parameters and computational resources as used in the conventional single-domain technique. Depending on the domain and model type, it is possible to perform 3-to-5 ensemble simulations on both coarse and fine meshes by applying the nesting technique and using the same amount of CPU-hours needed to complete one single-domain simulation. This research details the concept, preliminary results and offline applications of the tool. Future work is focused on enhancing the ease of use and on development and implementation of a real-time version.

Geological Assessment of the Khor Kharfot Sediments, Western Dhofar Region, Sultanate of Oman

Khor Kharfot is part of a coastal estuarine wetland system located in the western part of the Dhofar Governorate preserving a pristine ecosystem supporting a distinct vegetation and animal habitat. A sand barrier along the khor (local term for wetlands) mouth controls the mixing of fresh and marine water in the enclosed lagoon. In order to understand the geological controls on the khor formation, a geological map of the khor barrier and inlet area is prepared. The khor is bounded by Cretaceous and Tertiary carbonate rock sequences which are cut by a number of faults. The khor mouth and barrier are comprised of late Holocene deposits divided into seven units including i) beach sand, ii) beach sand mixed with wadi gravels, iii) scree and coastal dunes, iv) lagoon, v) soil and boulders, vi) wadi gravels, and vii) talus. The khor developed as an open estuary which changed to a barrier dominated lagoon due to falling fresh water supplies as a consequence of dwindling Khareef rains. The lagoon water is brackish due to the mixing of fresh and marine water and supports a distinct flora and fauna.

Modern sedimentary processes and seasonal variations of organic matter in an urban tropical estuary, Jaboatão River (PE), Brazil

ABSTRACT Barcellos, R.L., Flores-Montes, M.J., Alves, T.M.F. and Camargo, P.B. 2016. Modern sedimentary processes and seasonal variatios of organic matter in a urban tropical estuary, Jaboatao River (PE) Brazil. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 38–42. Coconut Creek (Florida), ISSN 0749-0208. The aim of this research is to evaluate the environmental conditions in the Jaboatao River estuarine system (8°14′S/34°55′W), by studying sedimentary organic matter, which may provide information about anthropogenic influence in this tropical mesotidal estuary. The catchment area is 442 km2 with a population estimated at 500,000 inhabitants, and is characterized as an urban coastal plain estuarine system. Thirty surface sediment samples were collected in November-2010 (dry season) and May-2011 (rainy season). Results indicated that the adjacent ...

Historical Mining Signatures: Geochemical and Mineralogical Evaluation of Sediments in three Coastal–Estuarine Systems

The X-ray fluorescence (XRF) of the inter-tidal sediments in Hayle, Gannel and Camel estuaries in southwest England’s coasts are examined here to evaluate and compare the broad geochemistry of each of the three systems. The total base cation content (Na, Mg and K) of the samples in all of the estuaries is 5% while the Ca is ~>20%. In terms of sub-environment significance, the estuarine and inlet sediments of Hayle exhibit a high content of Ca than the coastal/beach samples while both the Gannel’s estuarine and beach samples exhibit ~25% of Ca composition. There is high variation in the dimension of Ca in the different sub-environments sampled in Camel estuary (outerestuary – 25-28%, mid-estuary - ~20%, inner – 30%). The Al and Fe contents in all of the sites are below 2% except in Camel where Al is around 3.5%. There clear difference in the percentage of composition of trace elements among the estuaries is also evident. Sn’s concentration in Hayle is higher than that of Camel and Gannel. Pb, Ba, Zr and Zn is significant in all of the estuaries at various degrees - Pb and Zn are abundant in Gannel, while Sn, W, Zr prominent in Camel. The significant effect of the release of the particulate mine waste are observed in the samples’ mineralogical composition despite the cessation of the mine activities in the 19th/early 20th Century, suggesting that these elements are still bio-available and bio-active for riverine processes to transport/migrate in the estuary–coast interaction.

Assessing ecological community health in coastal estuarine systems impacted by multiple stressors

Increasing population pressure, urbanisation of the coastal zone and nutrient and sediment run-off from agriculture and forestry has increased the number of large-scale and chronic impacts affecting coastal and estuarine systems. The need to assess cumulative impacts is a major motivation for the current desire of managers and ecologists to define ecosystem “health” and “stress”. A number of univariate metrics have been proposed to monitor health, including indicator species, indicator ratios and diversity or contaminant metrics. Alternatively, multivariate methods can be used to test for changes in community structure due to stress. In this study we developed multivariate models using statistical ordination techniques to identify key stressors affecting the ‘health’ of estuarine macrofaunal communities. Macrofaunal and associated environmental samples were collected across 75 sites from within Tauranga Harbour, a large estuary located on New Zealand's North Island. The harbour receives discharges from urbanised, industrial, agricultural and horticultural catchments. Distance-based linear modelling identified sediments, nutrients and heavy metals as key ‘stressors’ affecting the ecology of the harbour. Therefore, three multivariate models were developed based on the variability in community composition using canonical analysis of principal coordinates (CAP). The multivariate models were found to be more sensitive to changing environmental health than simple univariate measures (abundance, species richness, evenness and Shannon–Wiener diversity) along an anthropogenic stress gradient. This multivariate approach can be used as a management or monitoring tool where sites are repeatedly sampled over time and tracked to determine whether the communities are moving towards a more healthy or unhealthy state. Ultimately, such statistical models provide a tool to forecast the distribution and abundance of species associated with habitat change and should enable long-term degradative change from multiple disturbances to be assessed.

Field and laboratory observations of bed stress and associated nutrient release in a tidal estuary

Nutrient release driven by sediment resuspension in a shallow coastal estuarine system is examined with field observations of bed stress and bed elevation, coupled with laboratory erosion experiments on sediment cores. Two field experiments were conducted over near-cohesive muddy-sand sediments in the Great Bay Estuary, New Hampshire. In the first deployment, boundary layer development during typical summer tidal forcing was observed, while the second deployment occurred under enhanced wind forcing of Tropical Storm Irene. In situ bed stress and erosion depths were estimated with a profiling acoustic Doppler velocimeter. Sediment cores were subjected to EROMES erosion chamber experiments to determine erosion depth and nutrient release as a function of applied shear stress. Results show erosion depths are consistent with in situ observations over shear stresses ranging from 0.10 N m−2 (incipient motion) to 0.35 N m−2 (resuspension events). Erosion chamber experiments showed that ammonium release (up to 2 mmol m−2) increased with bed stress in both spring and summer. However, phosphate release was more variable, with no phosphate release during resuspension in spring and a variable phosphate flux (ranging −0.5–2 mmol m−2) in summer. Increased hydrodynamic forcing during a storm event in the summer generated shear stresses (up to 0.58 N m−2) during flood tides that exceeded the threshold for sediment motion, and resulted in erosion of the seabed. EROMES results predict there was concomitant release of nutrients into the water column from the muddy sediments of the Bay, and the release of dissolved inorganic nitrogen and phosphate was up to 10% and 65%, respectively, of the summer monthly riverine input of these nutrients. Results indicate qualitatively that in shallow, tidally dominated estuaries, fine-grained sediment beds may be a source of nutrients that are particularly important during storms that enhance near bed shear stresses.

Diversity of the free-living marine and freshwater Copepoda (Crustacea) in Costa Rica: a review.

The studies on marine copepods of Costa Rica started in the 1990’s and focused on the largest coastal-estuarine systems in the country, particularly along the Pacific coast. Diversity is widely variable among these systems: 40 species have been recorded in the Culebra Bay influenced by upwelling, northern Pacific coast, only 12 in the Gulf of Nicoya estuarine system, and 38 in Golfo Dulce, an anoxic basin in the southern Pacific coast of the country. Freshwater environments of Costa Rica are known to harbor a moderate diversity of continental copepods (25 species), which includes 6 calanoids, 17 cyclopoids and only two harpacticoids. Of the +100 freshwater species recorded in Central America, six are known only from Costa Rica, and one appears to be endemic to this country. The freshwater copepod fauna of Costa Rica is clearly the best known in Central America. Overall, six of the 10 orders of Copepoda are reported from Costa Rica. A previous summary by 2001 of the free-living copepod diversity in the country included 80 marine species (67 pelagic, 13 benthic). By 2009, the number of marine species increased to 209: 164 from the Pacific (49% of the copepod fauna from the Eastern Tropical Pacific) and 45 from the Caribbean coast (8% of species known from the Caribbean Basin). Both the Caribbean and Pacific species lists are growing. Additional collections of copepods at Cocos Island, an oceanic island 530 km away of the Pacific coast, have revealed many new records, including five new marine species from Costa Rica. Currently, the known diversity of marine copepods of Costa Rica is still in development and represents up to 52.6% of the total marine microcrustaceans recorded in the country. Future sampling and taxonomic efforts in the marine habitats should emphasize oceanic environments including deep waters but also littoral communities. Several Costa Rican records of freshwater copepods are likely to represent undescribed species. Also, the biogeographic relevance of the inland copepod fauna of Costa Rica requires more detailed surveys.

Carbon dioxide emissions from estuaries of northern and northeastern Brazil.

The carbon dioxide flux through the air–water interface of coastal estuarine systems must be quantified to understand the regional balance of carbon and its transport through adjacent coastal regions. We estimated and calculated the emissions of carbon dioxide (FCO2) and the partial pressure of CO2 (pCO2) values in 28 estuarine environments at a variety of spatial scales in the northern and northeastern regions of Brazil. The results showed a mean FCO2 (water to air) of 55 ± 45 mmol·m−2·d−1. Additionally, a negative correlation between dissolved oxygen saturation and pCO2 was observed, indicating a control by biological processes and especially by organic matter degradation. This leads to increased dissolved CO2 concentration in estuarine waters which results in a pCO2 that reached 8,638 μatm. Our study suggests that northern and northeastern Brazilian estuaries act as sources of atmospheric CO2. The range of pCO2 observed were similar to those found in inner estuaries in other places around the world, with the exception of a few semi-arid estuaries (Köppen climate classification – BSh) in which record low levels of pCO2 have been detected.

Gastric nematode diversity between estuarine and inland freshwater populations of the American alligator (Alligator mississippiensis, daudin 1802), and the prediction of intermediate hosts.

We examined the variation of stomach nematode intensity and species richness of Alligator mississippiensis from coastal estuarine and inland freshwater habitats in Florida and Georgia, and integrated prey content data to predict possible intermediate hosts. Nematode parasitism within inland freshwater inhabiting populations was found to have a higher intensity and species richness than those inhabiting coastal estuarine systems. This pattern potentially correlates with the difference and diversity of prey available between inland freshwater and coastal estuarine habitats. Increased consumption of a diverse array of prey was also correlated with increased nematode intensity in larger alligators. Parasitic nematodes Dujardinascaris waltoni, Brevimulticaecum tenuicolle, Ortleppascaris antipini, Goezia sp., and Contracaecum sp. were present in alligators from both habitat types. Dujardinascaris waltoni, B. tenuicolle, and O. antipini had a significantly higher abundance among inland inhabiting alligators than hosts from estuarine populations. Our findings also suggest that host specific nematode parasites of alligators may have evolved to infect multiple intermediate hosts, particularly fishes, crabs, and turtles, perhaps in response to the opportunistic predatory behaviors of alligators.

Heavy metal concentration in mangrove surface sediments from the north-west coast of South America

Mangrove ecosystems are coastal estuarine systems confined to the tropical and subtropical regions. The Estero Salado mangrove located in Guayaquil, Ecuador, has suffered constant disturbances during the past 20years, due to industrial wastewater release. However, there are no published data for heavy metals present in its sediments and the relationship with anthropogenic disturbance. In the present study, metal concentrations were evaluated in surface sediment samples of the mangrove, showing that B, Cd, Cu, Pb, Se, V, and Zn levels exceeded those declared in international environmental quality standards. Moreover, several metals (Pb, Sn, Cd, Ag, Mo, Zn and Ni) could be linked to the industrial wastewater present in the studied area. In addition, heavy metal levels detected in this mangrove are higher than previous reports on mangrove sediments worldwide, indicating that this mangrove ecosystem is one of the most disrupted on earth.

Comparisons of statistical models to predict fecal indicator bacteria concentrations enumerated by qPCR- and culture-based methods

Recently, the United States Environmental Protection Agency (USEPA) revised their recreational water quality criteria, in which adjustments were made by approving enterococci (ENT) quantitative PCR (qPCR) as an alternative, rapid method and advocating the use of predictive models for water quality management. The implementation of qPCR-based methods and prediction models are meant to decrease the time between sample collection and public advisories and notifications. To date, few studies have compared qPCR-based models to culture-based prediction models and none of these studies have been conducted in coastal estuarine systems. In this study, we created prediction models using qPCR-based fecal indicator bacteria (FIB) data in dual-use recreational and shellfish harvesting waters and compared them to published ENT and Escherichia coli (EC) culture-based prediction models in eastern North Carolina estuaries. Furthermore, an empirical statistical model was created to predict qPCR inhibition levels so that proper remediation techniques can be applied when it is a problem. Predictor variable selection in both qPCR- and culture-based ENT models was very similar; both models included 14-day rain total, dissolved oxygen, and salinity/conductivity, with 89 and 90% of qPCR and culture data described, respectively. Using ENT management action thresholds, qPCR- and culture-based models showed high accuracy in management decisions. The qPCR model had 92 and 96% accuracy using the 110 and 1000 cell equivalents (CE)/100 ml thresholds, respectively, and the culture model had 90% accuracy in management decisions with the 110 MPN/100 ml threshold. EC models for qPCR- and culture-based concentrations used similar independent variables (14-day humidity, salinity/conductivity, a rain/storm variable, and a measure of air temperature), with each model explaining 26 and 55% of the data variation, respectively. When using different thresholds that were logs apart for management decisions, the two EC models accurately predicted management decisions; qPCR models correctly predicted management decisions 96 and 77% of the time (using 31 and 320 CE/100 ml, respectively) while culture models correctly predicted management decisions 96 and 88% percent of the time (with 31 and 320 MPN/100 ml, respectively). Equivalency between models was shown in our non-point source impacted estuaries, with ENT models performing slightly better than EC models. In addition, inhibition of the qPCR was a major issue that had to be addressed. An inhibition model was created with easily obtained meteorological data and accounted for a high level of data variability (adjusted R2 = 0.82).

Bioacumulation of trace elements in hepatic and renal tissues of the white mullet Mugil curema Valenciennes, 1836 (Actinopterygii, Mugilidae) in two coastal systems in southeastern Brazil

The aim of this study is to investigate the presence and the concentration of trace elements in hepatic and renal tissues of white mullet (Mugil curema) by Particle-induced X-ray emission (PIXE). Fish specimens were collected in two coastal areas of São Paulo state-Brazil: the Santos estuary (from March 2009 to February 2010) and the Cananéia-Iguape coastal estuarine system (from May 2008 to April 2009). For the elemental analysis, n=470 sample tissues (liver and kidney) were pooled according to location and type of organ. Trace elements such as Fe, Cu, Zn and Br were observed in both tissues of M. curema with concentrations ranging from 800μgg−1 for Fe to 7μgg−1 for Cu. The concentrations of Cu and Zn showed statistical significant differences among the tissues of M. curema (p<0.05). Relatively higher concentrations of Cu and Zn were observed in the liver tissue. There was no significantly difference in the elemental concentrations between the two studied areas. The Cu levels in liver tissues of M. curema were found to be above the maximum limits for consumption, according to the United States Environmental Protection Agency (EPA) and Brazilian National Health Surveillance Agency (ANVISA).

Sediment transport in the San Francisco Bay Coastal System: An overview

The papers in this special issue feature state-of-the-art approaches to understanding the physical processes related to sediment transport and geomorphology of complex coastal–estuarine systems. Here we focus on the San Francisco Bay Coastal System, extending from the lower San Joaquin–Sacramento Delta, through the Bay, and along the adjacent outer Pacific Coast. San Francisco Bay is an urbanized estuary that is impacted by numerous anthropogenic activities common to many large estuaries, including a mining legacy, channel dredging, aggregate mining, reservoirs, freshwater diversion, watershed modifications, urban run-off, ship traffic, exotic species introductions, land reclamation, and wetland restoration. The Golden Gate strait is the sole inlet connecting the Bay to the Pacific Ocean, and serves as the conduit for a tidal flow of ~ 8 × 109 m3/day, in addition to the transport of mud, sand, biogenic material, nutrients, and pollutants. Despite this physical, biological and chemical connection, resource management and prior research have often treated the Delta, Bay and adjacent ocean as separate entities, compartmentalized by artificial geographic or political boundaries. The body of work herein presents a comprehensive analysis of system-wide behavior, extending a rich heritage of sediment transport research that dates back to the groundbreaking hydraulic mining-impact research of G.K. Gilbert in the early 20th century.

Sand sources and transport pathways for the San Francisco Bay coastal system, based on X-ray diffraction mineralogy

The mineralogical compositions of 119 samples collected from throughout the San Francisco Bay coastal system, including bayfloor and seafloor, area beaches, cliff outcrops, and major drainages, were determined using X-ray diffraction (XRD). Comparison of the mineral concentrations and application of statistical cluster analysis of XRD spectra allowed for the determination of provenances and transport pathways. The use of XRD mineral identifications provides semi-quantitative compositions needed for comparisons of beach and offshore sands with potential cliff and river sources, but the innovative cluster analysis of XRD diffraction spectra provides a unique visualization of how groups of samples within the San Francisco Bay coastal system are related so that sand-sized sediment transport pathways can be inferred. The main vector for sediment transport as defined by the XRD analysis is from San Francisco Bay to the outer coast, where the sand then accumulates on the ebb tidal delta and also moves alongshore. This mineralogical link defines a critical pathway because large volumes of sediment have been removed from the Bay over the last century via channel dredging, aggregate mining, and borrow pit mining, with comparable volumes of erosion from the ebb tidal delta over the same period, in addition to high rates of shoreline retreat along the adjacent, open-coast beaches. Therefore, while previously only a temporal relationship was established, the transport pathway defined by mineralogical and geochemical tracers support the link between anthropogenic activities in the Bay and widespread erosion outside the Bay. The XRD results also establish the regional and local importance of sediment derived from cliff erosion, as well as both proximal and distal fluvial sources. This research is an important contribution to a broader provenance study aimed at identifying the driving forces for widespread geomorphic change in a heavily urbanized coastal-estuarine system. • XRD of bulk sand is a viable tool for provenance study. • Cluster analysis of XRD spectra successfully groups source with sink. • Mineralogical links define critical pathways. • Detailed transport pathways can be inferred from the XRD data.