Grantee Research Project Results
Final Report: CISNet San Pablo Bay Network of Environmental Stress Indicators
EPA Grant Number: R826940Title: CISNet San Pablo Bay Network of Environmental Stress Indicators
Investigators: Schladow, S. G. , Davis, Jay A , Young, T. M. , Thompson, Bobbi , Schoellhamer, D. , Werner, I. , Nur, N.
Institution: University of California - Davis , United States Geological Survey , Point Reyes Bird Observatory , San Francisco Estuary Institute
Current Institution: University of California - Davis , Point Reyes Bird Observatory , San Francisco Estuary Institute , United States Geological Survey
EPA Project Officer: Packard, Benjamin H
Project Period: October 1, 1998 through September 30, 2001
Project Amount: $599,764
RFA: Ecological Effects of Environmental Stressors Using Coastal Intensive Sites (1998) RFA Text | Recipients Lists
Research Category: Environmental Statistics , Aquatic Ecosystems , Ecological Indicators/Assessment/Restoration
Objective:
The overall objectives of this research project consisted of four major tasks: (1) determine spatial and temporal variability in anthropogenic and natural stressors; (2) develop and test indicators of ecological health and understand their natural variability; (3) identify relations among indicators to further refine their deployment; and (4) develop and demonstrate the monitoring network.
Summary/Accomplishments (Outputs/Outcomes):
This CISNet project was directed toward attaining an understanding of contaminant fluxes, contaminant distributions, and ecological impacts in San Pablo Bay, the northern most basin of San Francisco Bay. Concentrations of trace elements (Ag, Cd, Cr, Cu, Ni, Pb, Zn), organophosphate pesticides (e.g., diazinon), organochlorine pesticides (e.g., DDT), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) were monitored monthly in dissolved, suspended solid, and surficial sediment compartments across the San Pablo Bay study area. The majority of these concentrations varied in ways that would have been predicted from previous, less temporally and spatially dense monitoring studies. For example, the concentrations of several dissolved trace elements were strongly correlated with salinity, and current use dormant spray insecticides (e.g., diazinon) had peak concentrations during their winter application period. One unexpected finding was an early winter (December-January) increase in dissolved PAH concentrations by nearly two orders of magnitude that occurred across the entire study area. The source of this increase appears to be corresponding increases in airborne concentrations of fine-particle associated PAHs; sediment resuspension, hypothesized as a major driver of dissolved nonpolar organic dynamics in the proposal, contributed little to the dissolved PAH peaks. Because most of the airborne PAH mass is smaller than 0.5 µm, atmospherically derived PAHs would contribute to the “dissolved” fraction using typical experimental methods.
The distribution of contaminants among fine particles (< ~1 µm), coarse particles (> ~1 µm), and the dissolved phase has important implications for their impact on the ecosystem. Particle-bound contaminants released very slowly to the aqueous phase are expected to have significantly fewer toxic effects than those released more rapidly. Benthic organism exposure to nonpolar organic contaminants often is predicted using equilibrium partitioning models that do not account for varying rates of contaminant release. Organic matter normalized distribution coefficients of PAHs in the water column were significantly above linear partitioning predictions in October, February, and March, but the opposite trend occurred in November – January. Deviations from the partitioning model were not significantly correlated with suspended solids concentration or tidal parameters suggesting that resuspension of contaminated sediments did not drive the phenomenon. Atmospherically derived, submicron particle-associated PAHs appear to drive the temporal pattern of dissolved concentrations and particle-water distributions across this watershed. The very high sorption capacities of soot phases measured in previous research suggest that these colloidal particles may be a major sink for other nonpolar contaminants including organophosphate insecticides. The bioavailability of fine particle-bound contaminants currently is unknown. Related measurements with surficial sediments showed a strong relationship between the “readily desorbed” fraction of PAHs and the biota sediment accumulation factor (BSAF) of the compounds in a 28-day clam (Macoma nasuta) exposure. The equilibrium partitioning model predicts that BSAF values will be independent of sediment or chemical characteristics; the nearly five-fold variation in this parameter observed in this study indicates the importance of considering contaminant desorption rates in determining bioavailability and bioaccumulation.
Monitoring sublethal indicators of deleterious effects in organisms can foretell subtle and possibly long-term consequences of exposure to chemicals in the environment. Biochemical (stress proteins), cellular (lysosomal membrane stability), and histological (tissue damage) stress indicators were investigated in sediment dwelling organisms resident in San Pablo Bay – the bivalves Macoma balthica and Potamocorbula amurensis and the crustacean Ampelisca abdita. To study natural variability and the impact of natural stressors, the effects of natural stressors such as salinity and temperature fluctuations on selected stress indicators were investigated in laboratory studies. In addition, biomarker responses were measured in organisms exposed to two model toxicants, the heavy metal cadmium and the pyrethroid insecticide esfenvalerate. A link to higher trophic levels of the ecosystem was established in our study on the effects of dietary uptake of esfenvalerate in fish. Biomarkers in the selected species were validated in laboratory tests using sediments from six field sites in San Pablo Bay: M14, M19, MIC, PET, CAN and SOCR.
Results from our studies show that within an organism’s tolerance range, potential natural stressors are unlikely to affect the expression of heat-shock proteins (hsp60, hsp70). Stress proteins and histopathological lesions were reliable sublethal indicators of cellular effects of exposure to cadmium and esfenvalerate. Lysosomal membrane damage proved not to be a reliable indicator of exposure to xenobiotic compounds in these studies, most likely due to a lack of information on the effects of non-chemical stress. Although A. abdita was extremely sensitive to esfenvalerate, M. balthica proved to be tolerant to the compound. This raised questions with regard to bioaccumulation by clams and dietary transfer to higher trophic levels, which were addressed in a dietary exposure study using the teleost medaka (Oryzias latipes). It was found that sublethal concentrations of esfenvalerate administered via food caused increased expression of stress proteins and reduced reproductive success in these fish. Exposure of clams to field collected sediment samples from San Pablo Bay demonstrated that clam survival was correlated with the sum of heavy metals, sediment pesticide (aldrin) concentrations, and tissue concentrations of pp-DDD, a breakdown product of DDT. Stress proteins and histopathological lesions showed a complex organ-dependent response pattern. PAHs and organochlorine pesticides were the main groups of chemicals associated with changes in stress protein expression and histopathological lesions, in particular inflammation in digestive gland and gonads. Lysosomal membrane damage was associated with bioaccumulated cadmium and organochlorine pesticides and with total histopathologic lesion score, in particular macrophage aggregates in digestive gland and gonads and germ cell necrosis. Mortality of A. abdita correlated with 2,3-ring PAHs and the metals Cu, Cd and Pb in sediments. Stress protein analysis was not a sensitive indicator of exposure to xenobiotic compounds in A. abdita. In conclusion, although the stress proteins in the amphipod species A. abdita and lysosomal membrane damage in clams were of little diagnostic value in these studies, stress proteins and histopathological lesions were useful for the identification of organs affected by xenobiotic compounds and the major compounds responsible for the effects. Survival as the sum of all deleterious effects was not linked directly to any biomarker.
In general the impacted benthos observed in the Estuary margin sub-assemblage samples were most likely due to the elevated TOC concentrations and cumulative effects of elevated metals and pesticides in the sediments at those sites. Opportunistic and contaminant tolerant taxa that dominated the Estuary margin sites apparently are well suited for such conditions. The macrobenthos were useful indicators of sediment conditions at the sites sampled but provided only one piece of information about overall environmental condition at those sites. The information about benthic condition will be included with other information about sediment contamination, toxicity, bioaccumulation, and other biological effects providing a weight-of-evidence assessment of environmental condition of San Pablo Bay study area.
The ecological hazard to fish predators posed by persistent, bioaccumulative contaminants that accumulate in forage fish in the San Pablo Bay ecosystem was examined in open water, river, and marsh habitats. Two fish species were sampled, striped bass (juveniles) and staghorn sculpin, in order to obtain adequate spatial coverage of the targeted sampling locations. Monitoring chemical contamination of forage fish was demonstrated to be a valuable indicator of general risks to the fish predators in the ecosystem.
These species were shown to accumulate contaminant concentrations across the different habitats that exceed thresholds for predator risk. Due to their lower trophic position, the contamination signal was not as strong in these fish species as in their predators (cormorants), but quantitative data were obtained for PCBs, DDT, and selenium; mercury concentrations were quantified but near the limit of detection. Average DDT concentrations in striped bass (24 ppb wet) and sculpin (16 ppb wet) both exceeded a guideline of 14 ppb wet established by Environment Canada for protection of wildlife consumers of aquatic biota. Average mercury concentrations in striped bass (72 ppb wet) and sculpin (70 ppb wet) both exceeded the 33 ppb wet guideline also established by Environment Canada for protection of fish predators. Selenium concentrations were below the threshold for effects on fish predators. No established guideline exists for PCBs. Due to small sample sizes, only suggestive information was obtained on spatial and temporal trends. Chemical contamination was observed across the three habitat types sampled. The results did not suggest distinct spatial variation in PCBs, mercury, and selenium. DDT concentrations apparently were elevated at one marsh site. Some evidence of temporal variation also was observed, with higher selenium concentrations at all sites in 2000 than in 1999.
The ecological impacts of chemical stressors upon two bird species with different foraging niches in San Pablo Bay also was examined. Chemical analysis of eggs was performed to obtain integrative measures of the degree of food web contamination in San Pablo Bay and to investigate the possible effects of this contamination on egg hatchability. Annual monitoring of avian eggs was demonstrated to be a highly effective means of evaluating temporal trends and ecological risk due to persistent, bioaccumulative contaminants in both open water and marsh habitats.
Consistent with the high trophic position of double-crested cormorants and the tendency of many contaminants of concern to biomagnify in the food web, cormorant eggs contained easily measurable concentrations of several important contaminants. PCBs in cormorant eggs clearly approached a known threshold for embryo mortality. Concentrations of other contaminants of potential concern in San Pablo Bay, including DDT, mercury, and selenium, were below thresholds. Fail-to-hatch eggs did not contain consistently higher concentrations of any contaminant. Overall, the degree of contamination of cormorant eggs appears to be sufficient to cause a low rate of embryo mortality in the population. Significant interannual variation in concentrations of PCBs, DDT, and selenium was observed. The covariation of these different contaminants suggests that a trophic shift occurred between 1999 and 2000. This study demonstrated the feasibility and utility of using cormorant eggs for analysis of long-term trends in San Pablo Bay. Based on this success, the Regional Monitoring Program is continuing this monitoring and expanding it into other regions of San Francisco Bay.
This study also demonstrated the value of chemical analysis of song sparrow eggs as a tool for monitoring contamination in tidal marsh food webs. Song sparrows accumulated measurable concentrations of several priority contaminants. Interestingly, selenium concentrations in song sparrow eggs were higher than in cormorant eggs. None of the contaminants of concern in San Pablo Bay were near thresholds for toxic effects, and fail-to-hatch eggs did not appear to have elevated concentrations. Chemical contamination of the food webs that include song sparrows in these marshes appears not to pose a toxicological threat. However, the results of this study suggest that analysis of song sparrow eggs in more contaminated marshes would be a valuable indicator of the degree of contamination and might lead to concentrations that approach or exceed toxic thresholds, particularly for selenium. Significant variation among marshes and years was observed, with one marsh (Petaluma River) having distinctly lower concentrations of PCBs and DDE in 2001.
At all marsh sites during the focal years of 1999 to 2001, overall nest survivorship for the entire nest cycle was lower than 26 percent. Success at other sites in the region ranged from under 10 percent at the Suisun Bay sites and around 30 percent at China Camp and Petaluma Rivermouth sites. Success was lowest in 1997 and 1998, but increased slightly in the focal years of 1999-2001, although the trend among sites varied during that time. Predation (65 percent) was the most significant cause of nest failure at all sites. Tidal marsh Song Sparrow nest success is low both in San Pablo and Suisun Bay, but further analysis is needed to determine if this level of success may indicate a threat to population viability.
Egg hatchability was similar in 1999 and 2000. In 2001, hatchability was higher at all sites except at China Camp. Patterns are less clear in the proportion of nests where no eggs remained unhatched. Mean clutch sizes in San Pablo Bay tended to be smaller than in the Suisun Bay reference sites. China Camp had the consistently highest clutch size every year. The causes of geographic variation in clutch size are well known in some species but are unknown in the subspecies studied here.
One of the key questions that this project addressed related to the optimal sampling intensity (both spatial and temporal) for a monitoring program in San Pablo Bay and its environs, in particular, and for estuarine systems in general. For many of the constituents studied, water and sediment sampling agreed well with results from the lower intensity regional monitoring program. However, for PAHs our measured concentrations at some sites were two orders of magnitude higher than any previously recorded results in this region. Particle-bound PAH concentrations in air samples are significantly elevated during November through January in the region indicating that wet or dry particle deposition may drive the approximately two order of magnitude concurrent increase in operationally dissolved PAH concentrations in surface water. Winter is a time when monitoring measurements had not been taken in this region.
An implicit assumption of all monitoring programs is that the time scales associated with contaminant input are longer than the sampling interval, and the important spatial scales are larger than the spacing between sampling sites and therefore resolvable. As the PAH example here shows, if contaminant loading occurs over a short period it may be totally missed. The same holds true for spatial variations. In a highly dynamic system such as San Francisco Bay (characterized by the large tidal oscillations and the driving influence of the “controlled”, aseasonal throughflow of freshwater) with the episodic nature of the contaminant inputs to the system, these two factors will compound each other, making the likelihood of missing key events more likely.
Thus, a necessary condition for deciding upon an optimal sampling intensity is prior knowledge of both the system dynamics and the nature of the loadings and transformations that may occur. In the case of San Pablo Bay, we have highlighted one example where such knowledge can guide future monitoring. Specifically, monitoring in early winter at monthly intervals is the minimum requirement to start to resolve the PAH load into the system.
Journal Articles on this Report : 9 Displayed | Download in RIS Format
Other project views: | All 44 publications | 11 publications in selected types | All 9 journal articles |
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Type | Citation | ||
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Datta S, Do LV, Young TM. A simplified method for sampling and analysis of high volume surface water for organic contaminants using XAD-2. Journal of Environmental Science and Health Part B-Pesticides Food Contaminants and Agricultural Wastes 2004;39(2):225-234. |
R826940 (Final) |
not available |
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Ganju NK, Schoellhamer DH, Warner JC, Barad MF, Schladow SG. Tidal oscillation of sediment between a river and a bay: a conceptual model. Estuarine, Coastal, and Shelf Science 2004;60(1):81-90. |
R826940 (Final) |
not available |
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Warner J, Schoellhamer D, Burau J, Schladow G. Effects of tidal current phase at the junction of two straits. Continental Shelf Research 2002;22(11-13):1629-1642. |
R826940 (Final) |
not available |
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Warner JC, Schoellhamer DH, Schladow G. Tidal truncation and barotropic convergence in a channel network tidally driven from opposing entrances. Estuarine, Coastal, and Shelf Science 2003;56(3-4):629-639. |
R826940 (Final) |
not available |
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Warner JC, Schoellhamer DH, Burau JB, Schladow SG. Convergence generated by a salinity minimum. Estuarine, Coastal, and Shelf Science (submitted, 2004). |
R826940 (Final) |
not available |
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Werner I, Geist J, Okihiro M, Rosenkranz P, Hinton DE. Effects of dietary exposure to the pyrethroid pesticide esfenvalerate on medaka (Oryzias latipes). Marine Environmental Research 2002;54(3-5):609-614, Special Issue. |
R826940 (Final) |
not available |
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Werner I, Clark SL, Hinton DE. Biomarkers aid understanding of aquatic organism responses to environmental stressors. California Agriculture 2003;57(4):110-115. |
R826940 (Final) R825433 (Final) |
Exit Exit Exit |
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Werner I, Teh SJ, Datta S, Lu XQ, Young TM. Biomarker responses in Macoma nasuta (Bivalvia) exposed to sediments from northern San Francisco Bay. Marine Environmental Research 2004;58(2-5): 299-304. |
R826940 (Final) |
not available |
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Werner I. The influence of salinity on the heat-shock protein response of Potamocorbula amurensis (Bivalvia). Marine Environmental Research 2004;58(2-5):803-807. |
R826940 (Final) |
not available |
Supplemental Keywords:
water, sediments, estuary, adsorption, chemical transport, ecological effects, bioavailability, organism, cellular, population, cumulative effects, chemicals, toxics, particulates, PAHs, PNAs, PCBs, dioxin, metals, heavy metals, organics, dissolved solids, ecosystem, indicators, restoration, aquatic, habitat, integrated assessment, environmental chemistry, biology, engineering, ecology, hydrology, histology, modeling, monitoring, surveys, western, EPA Region 9,, RFA, Scientific Discipline, Toxics, Geographic Area, Waste, Water, Ecosystem Protection/Environmental Exposure & Risk, Bioavailability, Ecology, Ecosystem/Assessment/Indicators, Ecosystem Protection, Contaminated Sediments, pesticides, State, Chemistry, Ecological Effects - Environmental Exposure & Risk, Monitoring/Modeling, Environmental Monitoring, Pacific Northwest, Biology, Ecological Indicators, ecological effects, ecological exposure, monitoring, anthropogenic stresses, health effects, anthropogenic stress, advance warning system, fate and transport, regional monitoring program , biomarkers, industrial waste, natural stressors, contaminated sediment, coastal zone, CISNet Program, regional environmental health, biomonitoring, environmental stress, San Pablo Bay, environmental stressors, environmental stress indicators, biological markersRelevant Websites:
http://www.sfei.org/cmr/data/CISNetdata.htm Exit
http://edl.engr.ucdavis.edu/Projects/CISNet/cisnet.html Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.