Evaluation of Sediment Toxicity in Kaohsiung Harbor,Taiwan

The contamination and toxicity levels of sediments in Kaohsiung Harbor, Taiwan, were evaluated using different sediment quality guidelines (SQGs). Twenty dredged sediment samples were collected from various locations in the harbor. Distribution of polycyclic aromatic hydrocarbons (PAHs), heavy metals, nutrients, and total organic carbons in the sediment samples were investigated. Results from the sediment analyses show that the sediments contained significant amounts of organics, nutrients, metals, and PAHs. Based on the analyses using the SQGs, sediments dredged from Kaohsiung Harbor were moderately contaminated and most samples have a low and medium-low probability of toxicity pollution. Results show that industrial activities and urban sewage effluents are the major sources of contamination in the harbor sediments.     

Distribution of Phthalate Esters in Sediments of Kaohsiung Harbor,Taiwan

The major objectives of this research are to study the species and concentration of phthalate esters (PAEs), an organic endocrine disruptor, in the sediments of Kaohsiung Harbor, Taiwan. Twenty monitoring stations were installed in the waterways of Kaohsiung Harbor to collect sediment samples for analyzing six species of PAEs. Results of laboratory analyses show that concentrations of ΣPAE₆ in the harbor sediment are between 0.40 and 34.8 mg/kg with an average of 5.02 mg/kg. Among all chemicals, di-(2-ethylhexyl) phthalate (DEHP) is the major species that constitutes 92% of all chemicals found in the sediment. Where the spatial distribution of the chemicals is concerned, all rivers (i.e., Love River, Canon River, and Salt River) show the highest concentrations near the mouth where they discharge into the harbor. This indicates that major sources of pollution originate from the upstream municipal and industrial wastewater discharges. Distributions of PAEs during both wet and dry seasons show that PAEs are more easily disbursed in the receiving sea water, leading to a wider range of chemical distribution, and hence most of the chemicals are accumulated in the harbor water channel. The assessment of ecological toxicity indicates that concentrations of the 88% DEHP found in the sediment are higher than environmental risk limits (ERLs), implying that the Kaohsiung Harbor sediments pose potential risks to the local ecological system. Hence, an effective PAE management and control strategy must be developed and implemented in order to improve the harbor sediment quality, and keep the harbor ecological environment free from the interference of chemicals that interrupt endocrine hormones.     

Assessment of possible sediment toxicity of contaminated sediments in Port Jackson, Sydney, Australia

A considerable amount of chemical data is available for surficial sediments in Port Jackson. Some of the highest concentrations of heavy metals, organochlorines and polycyclic aromatic hydrocarbons of any capital port occur in sediments mantling shallow tributaries and embayments close to central Sydney. However, these data have limited ability to predict adverse effects on living resources and in the absence of toxicological data, sediment quality guidelines (SQG) have been used to assess the possible adverse biological effects of sedimentary contaminants in this estuary. Several SQGs are currently available for both fresh and marine environments, but the scheme used in the current study is based on empirical analysis of matching chemical and biological data compiled by the National Oceanographic and Atmospheric Administration (NOAA) in the U.S. The NOAA SQG can be used to assess individual chemicals, or to estimate the probability of acute sediment toxicity by calculating `mean quotients' for a large range of contaminants. Although many individual chemicals in sediment exceed SQG over extensive parts of Port Jackson, `mean quotient' results suggest that only a small proportion (1%) of the harbour may be highly toxic (74% probability of toxicity). However, sediment in a considerably larger proportion of the port (almost 25%) is estimated to have a 49% probability of being toxic using the `mean quotient' approach. These results are indicative at best and contemporaneous chemical/biological/ecotoxicological studies are needed to verify the applicability of SQG developed in the U.S. for use outside North America and site specific studies of this type are still required to determine the toxicity of sediments in Port Jackson.     

Sediment quality criteria in use around the world

 There have been numerous sediment quality guidelines (SQGs) developed during the past 20 years to assist regulators in dealing with contaminated sediments. Unfortunately, most of these have been developed in North America. Traditionally, sediment contamination was determined by assessing the bulk chemical concentrations of individual compounds and often comparing them with background or reference values. Since the 1980s, SQGs have attempted to incorporate biological effects in their derivation approach. These approaches can be categorized as empirical, frequency-based approaches to establish the relationship between sediment contamination and toxic response, and theoretically based approaches that attempt to account for differences in bioavailability through equilibrium partitioning (EqP) (i.e., using organic carbon or acid volatile sulfides). Some of these guidelines have been adopted by various regulatory agencies in several countries and are being used as cleanup goals in remediation activities and to identify priority polluted sites. The original SQGs, which compared bulk chemical concentrations to a reference or to background, provided little insight into the ecosystem impact of sediment contaminants. Therefore, SQGs for individual chemicals were developed that relied on field sediment chemistry paired with field or laboratory-based biological effects data. Although some SQGs have been found to be relatively good predictors of significant site contamination, they also have several limitations. False positive and false negative predictions are frequently in the 20% to 30% range for many chemicals and higher for others. The guidelines are chemical specific and do not establish causality where chemical mixtures occur. Equilibrium-based guidelines do not consider sediment ingestion as an exposure route. The guidelines do not consider spatial and temporal variability, and they may not apply in dynamic or larger-grained sediments. Finally, sediment chemistry and bioavailability are easily altered by sampling and subsequent manipulation processes, and therefore, measured SQGs may not reflect in situ conditions. All the assessment tools provide useful information, but some (such as SQGs, laboratory toxicity and bioaccumulation, and benthic indices) are prone to misinterpretation without the availability of specific in situ exposure and effects data. SQGs should be used only in a “screening” manner or in a “weight-of-evidence” approach. Aquatic ecosystems (including sediments) must be assessed in a “holistic” manner in which multiple components are assessed (e.g., habitat, hydrodynamics, resident biota, toxicity, and physicochemistry, including SQGs) by using integrated approaches. Received: December 26, 2000 / Accepted: December 28, 2001     

Probabilistic Risk Assessment and Risk Mapping of Sediment Metals in Sydney Harbour Embayments

Sediment metal concentrations in embayments of Sydney Harbour, acquired from the literature and from samples collected for this study, were used to generate contaminant probability density distributions using AQUARISK. The sediment metal concentrations often exceeded Australia's interim sediment quality guidelines. Similarly, estuarine spiked sediment toxicity test literature provided adverse biotic effects concentration data to generate species sensitivity distributions using AQUARISK. Although the harbor is subject to other inorganic and organic contamination, we have used sediment metals to demonstrate an approach for ecological risk mapping and environmental management prioritization. Sufficient spiked sediment toxicity test data were found for only three metals—Cd, Cu, and Zn—and some tests were likely to overestimate toxicity. The estimates of the hazardous concentration to 5% of species (the 50th percentile of the 95% species protection level) were 5, 12, and 40 mg/kg DW of total sediment metal for Cd, Cu, and Zn, respectively. These values were generally low when compared with the interim sediment quality guidelines due to the overestimation of toxic effects in the literature data. The parameters for the species sensitivity distributions have been combined with the measured sediment metal concentrations in Homebush Bay to generate risk maps of the estimated species impact for each metal as well as for all three metals collectively assuming proportional additivity. This has demonstrated the utility of comparing contaminants on a consistent scale—ecological risk.     

Soil washing improves the recovery of total community DNA from polluted and high organic content sediments

Treatment of soil with surfactants and chelating agents is used in bioremediation studies to desorb and solubilize contaminants to increase their bioavalability to microorganisms. In the same way that pollutants are made more bioavailable to microorganisms, the procedure can be used to remove potential interfering materials from soil prior to cell lysis and extraction of DNA from indigenous microorganisms. The effect of soil washing was evaluated by extracting DNA from sediments of an intertidal freshwater wetland contaminated with hydrocarbons and from highly contaminated marine sediments from Sydney Harbour, Nova Scotia, Canada. Sediment samples had total organic carbon (TOC) contents that varied between 0.2% and 13%. The chemical lysis technique was also examined by comparison of an ammonium acetate precipitation of proteins and humic acids with a hexadecyltrimethylammonium bromide (CTAB) incubation and phenol:chloroform extraction. In this study, the incorporation of soil washing steps facilitated the desorption of contaminants from sediment surfaces and improved the recovery of DNA of amplifiable quality from both freshwater and marine sediments. CTAB contributed only slightly to the recovery of DNA of higher quality in the most contaminated sample from Sydney Harbour and was concomitant with a decrease in DNA yield in both sediment types. The incorporation of a soil washing step prior to the extraction of DNA from polluted environments may be important to solubilize and remove contaminants when high-quality DNA is required for subsequent analyses.     

Origin and potential ecological risk assessment of trace elements in the watershed topsoil and coastal sediment of the Oualidia lagoon,Morocco

The Oualidia lagoon provides important ecosystem services, such as fishing, aquaculture, tourism and high biological and ecological productivity. Many indices have been developed to evaluate environmental risks and to estimate the anthropogenic contribution of potentially toxic elements (PTE) in surficial sediments. The results show that the concentrations of the PTE found in surface sediments due to the anthropogenic activities in the area (urban effluents, aquaculture and agricultural areas) are significantly higher than those from the local background and sediment quality guidelines (SQGs). The potential ecological and biological risk index present satisfactory results. However, the sites near to the areas where anthropogenic activities are developed present 49% probability of toxicity, while the rest of the lagoon, present 9% to 21% probability of toxicity and low potential ecological risk, except for Hg where the risk was considered to be considerable. The PTE are mainly originated from the anthropogenic activities; nevertheless, anthropogenic contributions represent up to 69% of the total sediment of content, but it depends on the PTE: Cd (16%), Ni (38%), Zn (41%), Cr (43%), Cu (56%), Hg (68%), Pb (69%). Compared with the Sub-basin soils, the PTE are higher than 80%, hence the sub-basin feeds the lagoon by these elements (PTE).     

An Overview of the Development,Status, and Application of Equilibrium Partitioning Sediment Benchmarks for PAH Mixtures

This article provides an overview of the development, theoretical basis, regulatory status, and application of the U.S. Environmental Protection Agency's (USEPA's) Equilibrium Partitioning Sediment Benchmarks (ESBs) for PAH mixtures. ESBs are compared to other sediment quality guidelines (SQGs) for PAHs. Data that examine the ability of the ESB approach to predict toxic effects to invertebrates are discussed. A USEPA draft methodology for the development of site-specific ESBs that takes into account the limited bioavailability of PAHs at certain sites is discussed. Research is presented that compares the ability of ESBs and site-specific ESBs to predict the toxicity of sediments collected from manufactured gas plants (MGPs). Site-specific ESBs that accounted for adsorption of PAHs onto black carbon were better predictors of the toxicity of sediments from MGP sites than ESBs that did not account for adsorption to black carbon.     

Polycyclic Aromatic Hydrocarbons in Coastal Sediment of Klang Strait,Malaysia: Distribution Pattern,Risk Assessment and Sources

Concentration, source, and ecological risk of polycyclic aromatic hydrocarbons (PAHs) were investigated in 22 stations from surface sediments in the areas of anthropogenic pollution in the Klang Strait (Malaysia). The total PAH level in the Klang Strait sediment was 994.02±918.1 µg/kg dw. The highest concentration was observed in stations near the coastline and mouth of the Klang River. These locations were dominated by high molecular weight PAHs. The results showed both pyrogenic and petrogenic sources are main sources of PAHs. Further analyses indicated that PAHs primarily originated from pyrogenic sources (coal combustion and vehicular emissions), with significant contribution from petroleum inputs. Regarding ecological risk estimation, only station 13 was moderately polluted, the rest of the stations suffered rare or slight adverse biological effects with PAH exposure in surface sediment, suggesting that PAHs are not considered as contaminants of concern in the Klang Strait.     

A new standardized sediment bioassay protocol using the amphipod Hyalella azteca (Saussure)

A new standardized bioassay procedure for testing the chronic toxicity of sediments to Hyalella azteca was developed. Tests were initiated with 0–1 wk old amphipods exposed to sediments from Hamilton Harbour, Toronto Harbour, and Lake Ontario for 4 to 8 weeks. Both survival and growth were significantly reduced in the Hamilton Harbour sediments relative to those from the lake after 4 weeks. Exposures of 8 weeks resulted in greater variability; survival of amphipods in sediments from one of the harbour stations, and growth in sediments from both harbour stations with surviving young were not statistically different from survival and growth in lake sediments. Growth and survival in lake sediments were comparable to cultures grown with cotton gauze and no sediment after 4 weeks, but survival was poorer by week 8. Replication was good in 12 out of 13 tests done in duplicate; the difference in survival between replicates averaged 2.2 animals (20 amphipods/replicate, 4 week exposure). We propose that 4 week exposures of young (0–1 wk old) Hyalella would provide a suitable standardized chronic toxicity test for sediments. A detailed protocol on the methodology is presented.     

Recommended Uses of Empirically Derived,Sediment Quality Guidelines for Marine and Estuarine Ecosystems

Sediment quality guidelines (SQGs), based upon empirical analyses of matching chemical and biological data, have been developed for many potentially toxic substances. The predictive abilities and recommended applications of two sets of guidelines, ERLs/ERMs and TELs/PELs, are discussed in this paper. The SQGs were intended as informal (i.e., non-regulatory) benchmarks to aid in the interpretation of chemical data. Low-range values (i.e., ERLs or TELs) were intended as concentrations below which adverse effects upon sediment-dwelling fauna would be expected only infrequently. In contrast, the ERMs and PELs represent chemical concentrations above which adverse effects are likely to occur. Evaluations of the reliability and predictive ability of the SQGs indicate they can be used effectively to assess the quality of soft, aqueous, sedimentary deposits. Specifically, the SQGs can be used to classify sediment samples with regard to their potential for toxicity, to identify contaminants of concern, and to prioritize areas of concern based on the frequency and degree to which guidelines are exceeded. Toxicity and bioaccumulation tests, toxicity identification evaluations, and benthic community assessments provide complimentary information for assessing sediment quality.     

An Overview of Metal Pollution in the Western Harbour of Alexandria,Egypt

Limited data are available on the concentration of metals in sediments in the Western Harbour of Alexandria. The most comprehensive record is from a survey conducted more than a decade ago. Industrial and human activities in and around this area have increased dramatically in the last 20 years. The purpose of this study was to determine the concentrations of heavy metals in surfacial bottom sediments of the harbor, to assess their potential biological effects and to identify their possible sources. Sediment samples from 21 stations throughout the harbor were analyzed for grain size, total organic carbon content (TOC), and metals (Al, As, Ba, Be, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Se, Sn, V, and Zn) to assess the extent of contamination in the area. The results indicated that concentrations of metals in the sediments varied widely depending on the location. High levels of metals were observed in the Arsenal Basin and the outfall area of El Mahmoudiya Canal in the inner harbor. The concentrations of metals were found to be higher than those recorded in the previous study. However, with some exceptions, most of the changes in the metal concentrations could be accounted for by the variations in aluminum, which represents the variations in mineralogy and grain size, indicating that the majority of the metals were of “natural” origin. The present data were also compared with results from other areas.     

Distribution of organochlorines and ecological risks in surface sediments from El-Mex Bay,Mediterranean Sea

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were determined in eight sampling sites collected from El-Mex Bay sediments during the period of 2013–2015. Concentrations of PCBs, Hexachlorocyclohexanes (HCHs), Dichloro Diphenyl Trichloroethanes (DDTs), and cyclodienes ranged from 0.148 to 23.99, ND to 0.089, ND to 4.64, and 0.005 to 0.581 ng g^?1 dry wt, respectively. Total organic carbon (TOC) was relatively low, ranging from 0.09% to 1.42%. Total carbonate content ranged from 38% to 58%. The negative correlation of TOC with total pesticides (r = ?0.18) suggested that TOC does not have a role binding with pesticides. On the other hand, a positive correlation between PCBs and TOC (r = 0.254 at p > 0.01) was observed probably due to the low solubility of PCBs in the seawater. So, it will continue to precipitate until it reaches the bottom water and contaminates the sediment. The data obtained in the present work compared well with the counterpart data reported internationally. In general, the results of PCBs and OCP concentrations in El-Mex Bay sediments were much lower than the permissible levels recorded by sediment quality guidelines (SQGs). Interestingly, the organochlorines in sediments of El-Mex Bay were below the respective SQG values and were not likely to pose potential biological adverse impact.     

Calculating Background Levels for Ecological Risk Parameters in Toxic Harbor Sediment

Establishing background levels for biological parameters is necessary in assessing the ecological risks from harbor sediment contaminated with toxic chemicals. For chemicals in sediment, the term contaminated is defined as having concentrations above background and significant human health or ecological risk levels. For biological parameters, a site could be considered contaminated if levels of the parameter are either more or less than the background level, depending on the specific parameter. Biological parameters can include tissue chemical concentrations in ecological receptors, bioassay responses, bioaccumulation levels, and benthic community metrics. Chemical parameters can include sediment concentrations of a variety of potentially toxic chemicals. Indirectly, contaminated harbor sediment can impact shellfish, fish, birds, and marine mammals, and human populations. This paper summarizes the methods used to define background levels for chemical and biological parameters from a survey of ecological risk investigations of marine harbor sediment at California Navy bases. Background levels for regional biological indices used to quantify ecological risks for benthic communities are also described. Generally, background stations are positioned in relatively clean areas exhibiting the same physical and general chemical characteristics as nearby areas with contaminated harbor sediment. The number of background stations and the number of sample replicates per background station depend on the statistical design of the sediment ecological risk investigation, developed through the data quality objective (DQO) process. Biological data from the background stations can be compared to data from a contaminated site by using minimum or maximum background levels or comparative statistics. In Navy ecological risk assessments (ERA's), calculated background levels and appropriate ecological risk screening criteria are used to identify sampling stations and sites with contaminated sediments.     

Heavy metals inUlva lactuca collected within Tolo Harbour,an almost landlocked sea

Summary The sea lettuce (Ulva lactuca), a littoral and sublittoral marine macroalga grows abundantly around shorewaters of Hong Kong, especially Tolo Harbour whereU.lactuca is collected from the mudflat for local human consumption as well as for export. Samples ofU.lactuca, together with the ambient seawater and sediment, were collected from several localities around Tolo Harbour, an almost land-locked sea, receiving polluted water from several major streams. For comparison samples were also collected from areas near the unpolluted south coast of Hong Kong Island. It was demonstrated that the samples of seawater and sediment collected within Tolo Harbour were polluted from domestic, agricultural and industrial sources. The extent of the metal (copper, lead, zinc and iron) contamination was further reflected and amplified in the tissue ofU.lactuca.     

Contrasting distributions of bacteriophages and eukaryotic viruses from contaminated coastal sediments

Viruses are ubiquitous, abundant and play an important role in all ecosystems. Here, we advance understanding of coastal sediment viruses by exploring links in the composition and abundance of sediment viromes to environmental stressors and sediment bacterial communities. We collected sediment from contaminated and reference sites in Sydney Harbour and used metagenomics to analyse viral community composition. The proportion of phages at contaminated sites was significantly greater than phages at reference sites, whereas eukaryotic viruses were relatively more abundant at reference sites. We observed shifts in viral and bacterial composition between contaminated and reference sites of a similar magnitude. Models based on sediment characteristics revealed that total organic carbon in the sediments explained most of the environmental stress-related variation in the viral dataset. Our results suggest that the presence of anthropogenic contaminants in coastal sediments could be influencing viral community composition with potential consequences for associated hosts and the environment.     

Biological responses of the sea urchin, Arbacia punctulata, to lead contamination for an estuarine ecological risk assessment

An estuarine ecological risk assessment for thePortsmouth Naval Shipyard (PNS) Kittery, ME, wasconducted utilizing the U.S. EPA's Framework forEcological Risk Assessment (ERA). As part of theanalysis phase of the ERA, laboratory studies wereconducted to develop quantitative exposure-responserelationships for lead (Pb), a key contaminant ofconcern for PNS, in order to evaluate the role of Pbin the ecological stress observed near PNS, and toestimate the probability of ecological risk associatedwith Pb contamination at the site. Biological effectsof exposure to Pb via sediment or diet were evaluatedusing several life stages of the sea urchin, Arbacia punctulata. This strategy was employedbecause echinoderm species, including A.punctulata, are amenable to laboratory testing andhave been used frequently to assess the toxicity ofestuarine waters and sediments. In addition, lifestage-specific biological effects could be comparedand integrated into projections of population-levelresponses to Pb. Results indicated that adult seaurchins accumulated Pb in direct proportion toexposure medium Pb concentration, whether exposureoccurred via sediment or diet. High Pb concentrationsreduced survival and gamete production in females, buthad no effect on the viability of produced gametes. Aqueous Pb exposure concentrations that producedadverse effects on adult sea urchin survival andreproduction were also directly toxic to early lifestages. In addition to their utility for this ERA,these results have applicability for the prediction ofbiological effects or the retrospective analysis ofcausal relationships at other estuarine sites.     

Distribution characteristics,sources, and ecological risk assessment of polycyclic aromatic hydrocarbons in sediments from Haizhou Bay,China

Sixteen USEPA priority polycyclic aromatic hydrocarbons (PAHs) were analyzed by gas chromatography–mass spectrometry. Twenty samples were collected from the surface sediments of Haizhou Bay in this survey. This research aimed to identify the PAHs' contamination level, composition pattern, pollution sources, and assess the ecological risk of PAHs. The results showed that the sum of PAH concentrations ranged from 116.6 ng g^?1 to 2414.9 ng g^?1 (mean: 662.42 ng g^?1), which is higher than the reported values for different wetlands worldwide. Three- and four-ring PAHs (accounts for more than 70% of the total PAH content) were predominant in the wetland sediment. The PAHs source distribution in the surface sediments were determined using diagnostic ratio and PCA/MLR. Consequently, multiple PAHs sources were found. Of the total PAH, 79.25% was derived from vehicular emission, 20.75% from coal combustion. The effect range low/effect range median (ERL/ERM) values indicated a low toxicity risk level. However, the fluoranthene concentrations exceeded the ERL level, and even the ERM level, in some stations. The mean effects range–median quotient (M-ERM-Q) suggests a low ecological risk for the PAHs in the sediments.     

Polycyclic aromatic hydrocarbons in surficial sediments and caged mussels of the St. Marys River, 1985

During 1985, a biological monitoring study was conducted in the St. Marys River to determine the availability and source areas of polycyclic aromatic hydrocarbons (PAHs) and the relative importance of water and sediment to tissue contaminant concentrations. Clean unionid mussels (Elliptio complanata) were exposed in cages for three weeks at 14 stations and surficial sediments were obtained at 12 of these. The highest concentrations of total PAHs as well as many individual compounds were found in sediments and mussels from the Algoma Steel Slip above St. Marys Falls and in sediments below the discharge of the Edison Sault Electric Co. Canal. Although concentrations were lower below the Falls, elevated levels persisted downstream along the Ontario shore into Lake George. PAHs were also accumulated by mussels exposed along the Michigan shoreline, but at lower levels than along the Ontario shore. From 23 to 63 percent of the PAHs in sediments and 6 to 27 percent of those in mussels were comprised of compounds with mutagenic and/or carcinogenic properties. The predominance of higher molecular weight PAHs in both sediments and mussels as well as lower molecular weight PAHs and nitrogen- and sulfur-containing PAHs in certain areas, indicates that high temperature combustion of fossil fuels is the major source of PAHs, augmented by localized spills of fossil fuels and coke oven by-products.Mussels contained fewer PAHs (up to 18 vs. 25) at lower concentrations (µg kg^-1 vs. mg kg^-1) than the associated surficial sediments. Also, mussels suspended at mid-depth in the water column accumulated similar concentrations to those exposed to sediments, indicating that the major exposure pathway is via the water filtered by these organisms, and hence, is due primarily to external industrial inputs.     

Weight-of-Evidence Issues and Frameworks for Sediment Quality (And Other) Assessments

Weight of evidence (WOE) frameworks for integrating and interpreting multiple lines of evidence are discussed, focusing on sediment quality assessments, and introducing a series of ten papers on WOE. Approaches to WOE include individual lines of evidence (LOE) as well as combined LOE (indices, statistical summarization, logic systems, scoring systems, and best professional judgment [BPJ]). The application of WOE, based on multiple LOE, is discussed relative to the published literature. Fully implementing WOE requires consideration of six main LOE in sediment (or other assessments); these LOE generally correspond to other causality considerations including Koch's Postulates. However, the issue of sediment stability is an additional consideration, and the use of tabular decision matrices is recommended in a logic system to address LOE described by others as “analogy”, “plausibility”, or “logical and scientific sense.” Three examples of logic system WOE determinations based on the Sediment Quality Triad and using tabular decision matrices are provided. Key lessons from these examples include the: generally limited utility of sediment quality value (SQV)-based LOE; need for BPJ; importance of ecological relevance; importance of assessing background conditions; and, need for appropriately customizing study designs to suit sitespecific circumstances (rather than application of “boiler-plate” assessments). Overall, more quantitative approaches are needed that better define certainty elements of WOE in an open framework process, i.e., statistical summarization culminating in a logic system incorporating BPJ.