The chemical form of accumulated trace metal in prey is important in controlling the bioavailabil... more The chemical form of accumulated trace metal in prey is important in controlling the bioavailability of dietary metal to a predator. This study investigated the trophic transfer of radiolabelled Ag, Cd and Zn from the polychaete worm Nereis diversicolor to the decapod crustacean Palaemonetes varians. We used 2 populations of worms with different proportions of accumulated metals in different subcellular fractions as prey, and loaded the worms with radiolabelled metals either from sediment or from solution. Accumulated radiolabelled metals were fractionated into 5 components : metal-rich granules (MRG), cellular debris, organelles, metallothionein-like proteins (MTLP), and other (heat-sensitive) proteins (HSP). Assimilation efficiencies (AE) of the metals by P. varians were measured from the 4 categories of prey (i.e. 2 populations, radiolabelled from sediment or solution). There were significant differences for each metal between the AEs from the different prey categories, confirming that origin of prey and route of uptake of accumulated trace metal will cause intraspecific differences in subsequent metal assimilation. Correlations were sought between AEs and selected fractions or combinations of fractions of metals in the prey-MRG, Trophically Available Metal (TAM = MTLP + HSP + organelles) and total protein (MTLP + HSP). TAM explained 28% of the variance in AEs for Ag, but no consistent relationships emerged between AEs and TAM or total protein when the metals were considered separately. AEs did, however, show significant positive regressions with both TAM and total protein when the 3 metals were considered together, explaining only about 21% of the variance in each case. A significant negative relationship was observed between MRG and AE for all metals combined. The predator (P. varians) can assimilate dietary metal from a range of the fractions binding metals in the prey (N. diversicolor), with different assimilation efficiencies summated across these fractions. TAM and/or total protein may represent an approximate minimum for trophic availability but neither of these alone is a fully accurate predictor.
California Governor Jerry Brown and former Secretary of the Interior Kenneth Salazar, in releasin... more California Governor Jerry Brown and former Secretary of the Interior Kenneth Salazar, in releasing the Bay-Delta Conservation Plan (BDCP) on July 25, 2012, stated that: "Science will guide how to best restore the [Bay-Delta] ecosystem and how much water can be exported." (Natural Resources Agency 2012) The proclamation did not state how this would be accomplished, but set a deadline at the close of 2013 for establishing decisions about how science will guide policy. Phil Isenberg, Chairman of the Delta Stewardship Council (DSC), noted that "policy makers need the scientific community to tell us what [the scientific community] needs, how their involvement should be structured, and when and where they should get involved." California is poised to take the next step in building a sciencebased water policy and our leaders want to hear from the science community about what that should look like.
The downstream distribution of Cu, Cd, and Pb in fine-grained sediments and benthic insect larvae... more The downstream distribution of Cu, Cd, and Pb in fine-grained sediments and benthic insect larvae of the Clark Fork River, Montana is characterized. This river has been heavily con laminated as a result of past mining and smelling operations near its headwaters. Concentrations of all metals in bed sediments displayed a simple exponential downstream decrease through the upper 181 km of the river. The trend suggested metal contamination originated from source(s) in the headwaters, with physical dilution occurring downstream. Additional data suggested floodplain sediments also were contaminated by the original source(s). Secondary inputs from cutbanks in the floodplains may have extended the downstream influence of the contamination. The exponential model predicted that sediment contamination should extend at least 550 km downstream, a result that was verified with data from a separate, independent study. Metal contamination, as observed in all taxa of insect larvae collected from the ...
Many of the methodologies for effective use of organisms to monitor and study contamination in es... more Many of the methodologies for effective use of organisms to monitor and study contamination in estuaries are well established (Phillips, 1980; Phillips and Rainbow, 1993). Understanding the processes that determine bioaccumulation and determining concentrations of contaminants in biological tissues are best employed in conjunction with analysis of other environmental media (e.g., water, suspended particulate material, or sediment). Together these provide complementary lines of field evidence indicative of complexities that affect the exposures of organisms to contaminants. While tissue analysis is not universally suitable as a measure of exposure for all contaminants in all organisms or all circumstances, it does have important advantages when properly used: 1. Concentrations in tissues may be more responsive to environmental contamination than concentrations in water and/or sediments in some circumstances, providing a unique perspective on understanding exposures. 2. Measurements o...
Metal toxicity is affected by how organisms internally compartmentalize metals. This study compar... more Metal toxicity is affected by how organisms internally compartmentalize metals. This study compared the concentrations and intracellular distributions of Cd and Cu among hydropsychid caddisflies, Hydropsyche spp. and Arctopsyche grandis, and mayflies, Baetis spp. and Serratella tibialis, from contaminated sites in the upper Clark Fork river, Montana, and from an uncontaminated tributary (Blackfoot River). Bioaccumulation patterns exhibited species and metal specificity. Relative to uncontaminated samples, intracellular metal accumulation was greater in mayflies than in caddisflies. For example, Cd concentrations in the cytosol (soluble cytoplasm) were 7 - 13 (g/g in Serratella and Baetis and 0.4 - 2 (g/g in Hydropsyche and Arctopsyche. Cytosolic Cu concentrations were highest in Serratella (111 (g/g), and similar in Baetis, Hydropsyche and Arctopsyche (27 - 44 (g/g). The cytosol was a major accumulation site for Cd. Cadmium and Cu accumulation in the cytosol of Arctopsyche and Baetis was accompanied by a shift in the distribution of metal from “heat stable” (metal binding) to “heat denatured” (essential) proteins. The relatively high intracellular metal concentrations in Serratella and Baetis are supportive evidence of the reported metal sensitivity of mayflies. Species - specific toxicity may be further modified by how excess metal is partitioned among cytosolic ligands
Sixteen years ago, in October 2003, San Francisco Estuary and Watershed Science (SFEWS) published... more Sixteen years ago, in October 2003, San Francisco Estuary and Watershed Science (SFEWS) published its first article. An anniversary like this is a good time to remind ourselves of our history, and to ask if the journal is living up to the goals we set in 2003. And if so, are those goals consistent with today’s needs? In 2004, CDL’s eScholarship Publishing Group counted an average of 254 requests per month for SFEWS online articles. In 2010, that increased to 1,232 requests per month, and in 2014 to 1,764 per month. In the first 10 months of 2019, 4,420 articles were requested per month. Downloads have been consistently 35% to 40% of requests. Taking data from 2014 through 2017, the search engine Scopus’ CiteScore for SFEWS increased from 0.32 to 1.64; its rank is 82nd of 203 journals in the Water Science and Technology category for 2018, a remarkable climb from being ranked 120 of 179 in 2014. SFEWS is ranked fifth among 53 open access journals in the aquatic sciences, according to ...
Reproduction and condition of Potamocorbula amurensis were compared with cadmium concentration in... more Reproduction and condition of Potamocorbula amurensis were compared with cadmium concentration in the tissues of individual P. amurensis from five stations in northern San Francisco Bay to determine if either parameter could be used to assess ecosystem effects of trace metal contaminants. There is a gradient in cadmium content (ug/animal) and concentration (ng/g dry tissue) in tissues of clams which follows the freshwater gradient, with the freshest stations having the highest levels of cadmium contamination. Condition decreases with increasing cadmium content; animals from Honker Bay and Chipps Island have the highest cadmium content and lowest condition and those from San Pablo Bay have the lowest cadmium levels and highest condition. Synchrony in spawning was similarly related to cadmium content; animals with the highest cadmium concentration have asynchronous spawning. Asynchrony is potentially deleterious to organisms which depend on external fertilization, and thus may indicate that the reproductive success of other organisms in Suisun and San Pablo Bays may be harmed. The number of reproductive cycles, timing of reproduction, speed with which animals regain weight after spawning, and amount of weight gained during spawning, are most strongly related to food availability. Introduction The ecosystem effects of trace contaminants are the subject of ongoing discussions within San Francisco Bay regulatory agencies. Water-quality standards for all trace contaminants will be established within the next few years, and will be based on the ecological effects of each of the metals. Water-quality standards are established after preliminary standards are published, reviewed by the public, modified, and then subjected to further review. These regulatory processes will take several years to complete and the decisions will be aided by data describing the ecological effects of these contaminants. Trace-metal concentrations in San Francisco Bay are presently being assessed by analyzing the water column and the sediment, by doing bioassay tests on specific organisms, and by studying tissue burdens in some species. Although the ultimate goal of these studies is to determine what level of contamination results in harmful effects to the ecosystem, none of these approaches directly measures the effect of contaminants on the ecosystem. The major reason that direct measures of ecosystem effects have not been made is that the complexity of ecological processes can hide correlations between organism, population, or community changes and trace element concentrations. Some of this complexity is reflected in the way in which contaminants can affect animals and the communities in which they live. Chemical-biological interactions at the molecular level within an organism can influence developmental stages resulting in reproductive abnormalities, toxicity and adaptation due to changes in metabolic processes, and cellular damage due to effects on mitotic processes. At the organism level, contaminant stress can be seen with changes in physiology, behavior, reproductive success, larval success, and rates of parasitism and disease. At the more complex population level, changes in mortality, recruitment, biomass, production, and the structure of age and size classes are all possible effects of contaminants. At the community level, contaminant exposure may result in changes in species diversity, species composition, secondary production, and biomass. However, environmental stress, eg. osmotic and thermal extremes, can also cause many of the same effects. Thus, if ecosystem effects of contaminants are to be measured, it is necessary to examine selected parameters in a manner in which environmental and contaminant stresses can be separated. This report is the first step in looking at ecosystem effects of trace elements. Two life history parameters, reproductive periodicity and condition (change in tissue weight for a specific size of animal) of one species, Potamocorbula amurensis, are examined within a reach of San Francisco Bay that has a known trace metal concentration gradient (Brown and Luoma 1995). The contaminants within this gradient appear to originate with the freshwater inflow, i.e. the affected these parameters in the vicinity of our four upstream stations (figs. 3 and 4). Until 1986 the northern estuary had a late summer to early fall phytoplankton bloom (fig. 5). The cessation of this annual phytoplankton bloom since 1986 coincided with the introduction of Potamocorbula amurensis and it is believed that the lack of a phytoplankton bloom is due to over grazing by this filter feeder (Alpine and Cloern 1992). Therefore the major sources of food for P. amurensis, a filter feeder, are a combination of riverborne detritus and river derived phytoplankton in addition to locally grown phytoplankton, which never reaches high biomass levels. Each of these sources has a different seasonal and interannual pattern (fig. 6). The riverborne detritus is richest in non-refractory carbon at the beginning, not the peak, of the freshwater runoff during each year (Hagerand Schemel 1996) and was, no doubt, quite high in early 1993 when the drought ended. River chlorophyll a peaks in late spring and summer, but its transport into the bay is dependent on the amount and timing of freshwater runoff, so its quantity and seasonality vary between years. Growth rates of locally derived phytoplankton are dependent on light availability (Cloern 1987) and in this part of the estuary the growth rates usually peak in summer and fall. Summary of Contaminant and Condition Data Both cadmium content (jig in a 15mm animal, fig. 7) and concentration (|ig/g dry tissue, fig. 8) show a down-bay gradient with highest values seen in Honker Bay animals and the lowest values seen in San Pablo Bay animals (Brown and Luoma, written commun., 1996). Annual mean cadmium content was highest in 1993 in animals from the three upstream stations, showed little annual variation in Carquinez Strait animals, and was lowest in 1993 in San Pablo Bay animals (fig. 9). Condition for P. amurensis was generally higher at the down bay stations than at the freshest stations (fig. 10). Annual mean condition (fig. 11) was highest in animals from the seaward stations, San Pablo Bay and Carquinez Straits, and lowest in animals from Honker Bay. Methods Collection Methods To determine the reproductive pattern and gonadal development of P. amurensis, monthly samples were collected from the four channel stations and one shallow station for a period of 47 months, from January 1991 to December 1994. Animals representative of the size range present at each site were collected on the United States Geological Survey (USGS) research vessel Polaris with a Van Veen grab (0.05 m2) and rinsed through a 0.5 mm sieve, and preserved in 10 percent buffered formalin. Fifteen clams were examined for reproductive condition during 1991 for each sampling date and station and 10 clams were examined for each sampling date and station for the remaining years. There were several periods at all stations when no clams were found (table 2) and some periods when the sample size was reduced due to tissue damage during histological preparation. Reproductive Tissue Preparation Clam tissue was prepared and thin-sectioned by Bay Histology (San Rafael, California). The visceral mass of each clam was removed, stored in 70 percent ethyl alcohol, and then prepared using standard histological techniques: tissues were dehydrated in a graded series of alcohol, cleared in toluene (twice for one hour each), and infiltrated in a saturated solution of toluene and Paraplast for one hour, and two changes of melted Tissuemat for one hour each. Samples were then embedded in Paraplast in a vacuum chamber. The embedded samples were thin sectioned (10 Hm) using a microtome and then stained with Harris' hematoxylin and eosin. The stained thin sections were examined with a light microscope. Each specimen was characterized by size (length), sex, developmental stage and condition of the gonads thus allowing each specimen to be placed in one of five qualitative classes of gonadal development. Categories of Gonadal Development (Adapted from Rosenblum 1981) Female Gonads: Inactive Phase. Sex may be difficult or impossible to determine. Small ovocytes occur at the periphery of alveoli. A round nucleus in the ovocyte, encircled by an irregularly shaped cytoplasm, contains a conspicuous nucleolus. Follicle cells completely imbed the ovocytes and may fill the lumina of alveoli. Active Phase. Definite qualitative and quantitative changes in the gonads occur. Enlarging ovocytes grow between follicle cells towards the centers of alveoli. The ovocytes may be subconical, hemispherical, or cylindrical in shape, are rounded at the apices, and have broad cytoplasmic bases attaching them to the walls of the alveolus. Ripe Phase. Ovocytes appear as round cells in the lumina of the alveoli as if free of attachment to the basal membrane, but attachment is via a slender stalk. The nuclei of the largest ovocytes contain amphinucleoli, each consisting of an almost transparent nucleolus and a small opaque nucleolus membrane in cross section. The large ovocytes that fill the lumina are generally more numerous than the less-developed ovocytes. Partially Spawned Phase. Gonadal tissues contain a few ripe ovocytes. Small ovocytes are imbedded in follicle cells at the periphery of an empty alveolus. Many alveoli are devoid of ripe
Fine-grained, oxidized, surface sediments and two benthic bivalves (Corbi cul a sp., a suspension... more Fine-grained, oxidized, surface sediments and two benthic bivalves (Corbi cul a sp., a suspension-feeding freshwater clam, and Macoma balthica, a deposit-feeding brackish water clam) were used to examine spatial distributions of selenium within San Francisco Bay and the Sacramento/San Joaquin River Delta and to compare riverine with local inputs of biologically available selenium to this large, complex, urbanized estuary. Selenium concentrations in Corbicula were elevated in the western Delta and northern reach of San Francisco Bay compared to concentrations in Corbicula from river systems not enriched in selenium. Biologically available selenium did not appear to enter the southern Delta or northern reach of the Bay from the San Joaquin River, a possible source, in levels that could measurably influence bioaccumulation by Corbicula. Selenium concentrations in Macoma b a 1t h i c a also were elevated in southern South San Francisco Bay and near the western edge of Suisun Bay.
A preliminary study for the period February"July 1983 was completed in Suisun Bay, a shallow emba... more A preliminary study for the period February"July 1983 was completed in Suisun Bay, a shallow embayment of the San Francisco Bay system, California, to determine characteristic heavy metal concentrations present in sediments and organisms (Corbicula clams). Preliminary results show that the sediments of the study area are typical of other San Francisco Bay study sites. Sediments range from coarse sands to fine silt-clays and are enriched in manganese, with concentrations ranging from 24 to 818 M8/S (micrograms per gram), and are low in total organic carbon, with values ranging from 0.014-to 1.62-percent carbon. Iron is moderately enriched with acid-extractable iron concentrations of 162 to 3,521 |Jg/g. Concentrations of silver, zinc, lead, and cadmium measured in sediments between April and July are reported. Other San Francisco Bay studies have shown that pulses of increased concentrations occur during autumn and winter, a sampling period not covered in this data set. Lead concentrations range from 24 to 59 Mg/g. Cadmium concentrations range from less than 0.05 to 0.63 M8/S-Acidextractable copper concentrations range from 1.3 to 32.6 M8/8-Because of the paucity of data to date, interpretations separating physical and chemical influences on concentrations are not yet complete. Clam-tissue burdens for silver and zinc are similar to those found in Corbicula from pristine areas. Silver concentrations range from 61 to 332 nanograms per gram, and zinc ranges from 110 to 349 Mg/g. Copper concentrations range from 41 to 155 Mg/g. Cadmium levels range from 0.3 to 5.6 pg/g in Corbicula tissues.
^ The impacts of trace contaminants in aquatic environments cannot be assessed realistically with... more ^ The impacts of trace contaminants in aquatic environments cannot be assessed realistically without a greater understanding of the factors controlling the biological availability of the concentrated pool of metals associated with sediments. It has been established that direct uptake of (at least some) trace metals from sediments contributes to metal concentrations in benthic organisms. Important controls on metal uptake from sediment are the concentration of the exposure, the partitioning of the metals among components of the sediment, and the redox potential of the sediment. Important problems in ecology, physiology, geochemistry and biogeochemistry remain unresolved, however, and a concentrated interdisciplinary research effort will be necessary before a complete understanding of the fate and impact of sediment-bound metals will be possible.
The environmental dynamics of mercury were studied in Ala Wai Canal, a small Hawaiian estuary. Th... more The environmental dynamics of mercury were studied in Ala Wai Canal, a small Hawaiian estuary. Three indicator species were used in the study-the detritus feeding PoJ.i~haete Nereis succinea and shrimp Palaemon debilis and the predc.ceous decapod Thalamita crenata. The study employed laboratory experiments, utilizing 203-HgC12, and analyses of total mercury concentrations in sediment and biota samples collected periodically from the estuary. The two detritus feeders concentrated dissolved 203-Hg from 160 to 310 times over the concentration in seawater. Reduced salinity inhibited 203-Hg uptake by the worm but had little effect on uptake by the shrimp. Dissolved organic material also reduced 203-Hg accumulation. Little 203-Hg was accumulated from labelled estuarine sediment by either species-the steady state concentrations of 203-Hg in the animals ranged from only 0.25% to 1.5% of the concentration in the sediment. However, 203-Hg bound to sediment originating from urban street runoff was more available to both species than was 203-Hg bound to estuarine sediment. The availability of 203-Hg from runoff sediment declined as the sediment aged in seawater. Net loss of mercury occurred by way of two mono-exponential processes in both organisms and was slow relative to net accumulation. Total mercury analyses illustrated that mercury concentrations in sediment in Ala Wai Canal showed no obvious pattern of temporal variation. However, there was an obvious decrease in total mercury in the two detritus feeders between the rainy season and the dry summer months. Samples of~. debilis were collected at five day intervals during the rainy season. The equations describing accumulation and
Uptake from food and water and loss of 203 HgCl2were studied in two detritus feeders, the polyaha... more Uptake from food and water and loss of 203 HgCl2were studied in two detritus feeders, the polyahaete Nereis succinea and the shrimp Palaemon debilis, from a small Hawaiian estuary. During 1973 to 1974, total meraul'y analyses were also aonduated on sediment and biota samples aoUeated from the estuary. Detritus feeders aonaentrated dissolved 203Hg from 160 to 310 times over the aonaentration in sea water. LitUe 203 Hg was aaaumu lated from labelled estuarine sediment; the steady state aonaentration of 203Hg in the animals was 0.0025 to 0.015 times the aonaentration in the sediment the animals ingested. Net exaretion of 203 Hg was slow relative to aaaumulation in both spea-ies. The total meraul'y aontent of shrimp and woms ao l leated from the estuary sh01JJed a temporal pattern of variation. Samples of shrimp aoUeated at five day intervals were used, with a mathematiaal desaripi;ion of the aaaumulation and loss of metal by the shrimp to simulate biotia meraul'y dynamias in the estuary. The simulation showed that merau;py leve ls in shrimp in the Ala Wai Canal 1JJere never at steady state over the 1973-74 sampling period, and indiaated the most important sourae of biologiaally available meraU!'Y in the estuary was some inorgania, solute form of the metal.
A field and laboratory study of hibernation in, Zapus prinaeps was■ conducted.-Males gained weigh... more A field and laboratory study of hibernation in, Zapus prinaeps was■ conducted.-Males gained weight more ■ gradually, and reached a higher ■ weight peak than,female Z. pvinoeps. Hibernation was preceded in all animals by a period of lethargy and weight loss during which body temperatures were very 'labile.. Torpor was easily induced during the, summer by removing either food or.water from Zapus at ,any temperatures' below 220, Arousal from induced torpor during the summer,did not occur at. temperatures below TOO,, probably due to a lack of a suffix cient amount.of brown fat.-Animals kept at,constant temperature (3±1C) in 24 hours of light per day hibernated two,to three weeks later, than animals caged puts.ide.. The characteristics' of hibernation/ in Z. pvbnoeps appear to place it between the larger obligatory hibernators and the-smaller mammals that hibernate.. * .Differences between percentages of initial weight gained per day in the two groups were not significant (p-c.075) (Lentner, 1968).
Proceedings of the Water Environment Federation, 2009
ABSTRACT Since 2004, a group of over 20 stakeholders have been implementing a comprehensive progr... more ABSTRACT Since 2004, a group of over 20 stakeholders have been implementing a comprehensive program to address sources of nitrogen and selenium in the Newport Bay watershed in Orange County, California. The collaborative, stakeholder driven effort, the Nitrogen and Selenium Management Program (NSMP), included the development of a site-specific objective (SSO) for selenium. A tissue-based SSO has been developed that represents a unique shift from traditional water column based standards. The SSO developed through the NSMP is an example of a how a collaborative, stakeholder driven effort provided an opportunity for federal, state, regional, and local agencies to work with the regulated community and environmental non-profit organizations in order to develop a comprehensive, progressive, and unique approach to water quality management.
Ecological Assessment of Selenium in the Aquatic Environment, 2010
To date there has been no clear guidance for assessing the potential environmental effects and im... more To date there has been no clear guidance for assessing the potential environmental effects and impacts of selenium (Se) contamination; such activities have been highly site-specific. A Society of Environmental Toxicology and Chemistry (SETAC) Pellston Workshop held February 22-28, 2009, which involved a multidisciplinary and international group of scientists, managers and policymakers, established the present state of the science and provided globally-applicable guidance for assessing and managing the environmental effects of Se. Key information from the SETAC Pellston includes: traditional methods for predicting toxicity on the basis of exposure to dissolved concentrations do not work for Se; enrichment functions can be used to predict Se bioaccumulation at the base of food webs; uptake by individual species and in steps of the food web can be described by a trophic transfer function; Se partitioning is unique among metal and metalloid contaminants and requires site-specific risk assessments to a much greater extent than most other contaminants.
The chemical form of accumulated trace metal in prey is important in controlling the bioavailabil... more The chemical form of accumulated trace metal in prey is important in controlling the bioavailability of dietary metal to a predator. This study investigated the trophic transfer of radiolabelled Ag, Cd and Zn from the polychaete worm Nereis diversicolor to the decapod crustacean Palaemonetes varians. We used 2 populations of worms with different proportions of accumulated metals in different subcellular fractions as prey, and loaded the worms with radiolabelled metals either from sediment or from solution. Accumulated radiolabelled metals were fractionated into 5 components : metal-rich granules (MRG), cellular debris, organelles, metallothionein-like proteins (MTLP), and other (heat-sensitive) proteins (HSP). Assimilation efficiencies (AE) of the metals by P. varians were measured from the 4 categories of prey (i.e. 2 populations, radiolabelled from sediment or solution). There were significant differences for each metal between the AEs from the different prey categories, confirming that origin of prey and route of uptake of accumulated trace metal will cause intraspecific differences in subsequent metal assimilation. Correlations were sought between AEs and selected fractions or combinations of fractions of metals in the prey-MRG, Trophically Available Metal (TAM = MTLP + HSP + organelles) and total protein (MTLP + HSP). TAM explained 28% of the variance in AEs for Ag, but no consistent relationships emerged between AEs and TAM or total protein when the metals were considered separately. AEs did, however, show significant positive regressions with both TAM and total protein when the 3 metals were considered together, explaining only about 21% of the variance in each case. A significant negative relationship was observed between MRG and AE for all metals combined. The predator (P. varians) can assimilate dietary metal from a range of the fractions binding metals in the prey (N. diversicolor), with different assimilation efficiencies summated across these fractions. TAM and/or total protein may represent an approximate minimum for trophic availability but neither of these alone is a fully accurate predictor.
California Governor Jerry Brown and former Secretary of the Interior Kenneth Salazar, in releasin... more California Governor Jerry Brown and former Secretary of the Interior Kenneth Salazar, in releasing the Bay-Delta Conservation Plan (BDCP) on July 25, 2012, stated that: "Science will guide how to best restore the [Bay-Delta] ecosystem and how much water can be exported." (Natural Resources Agency 2012) The proclamation did not state how this would be accomplished, but set a deadline at the close of 2013 for establishing decisions about how science will guide policy. Phil Isenberg, Chairman of the Delta Stewardship Council (DSC), noted that "policy makers need the scientific community to tell us what [the scientific community] needs, how their involvement should be structured, and when and where they should get involved." California is poised to take the next step in building a sciencebased water policy and our leaders want to hear from the science community about what that should look like.
The downstream distribution of Cu, Cd, and Pb in fine-grained sediments and benthic insect larvae... more The downstream distribution of Cu, Cd, and Pb in fine-grained sediments and benthic insect larvae of the Clark Fork River, Montana is characterized. This river has been heavily con laminated as a result of past mining and smelling operations near its headwaters. Concentrations of all metals in bed sediments displayed a simple exponential downstream decrease through the upper 181 km of the river. The trend suggested metal contamination originated from source(s) in the headwaters, with physical dilution occurring downstream. Additional data suggested floodplain sediments also were contaminated by the original source(s). Secondary inputs from cutbanks in the floodplains may have extended the downstream influence of the contamination. The exponential model predicted that sediment contamination should extend at least 550 km downstream, a result that was verified with data from a separate, independent study. Metal contamination, as observed in all taxa of insect larvae collected from the ...
Many of the methodologies for effective use of organisms to monitor and study contamination in es... more Many of the methodologies for effective use of organisms to monitor and study contamination in estuaries are well established (Phillips, 1980; Phillips and Rainbow, 1993). Understanding the processes that determine bioaccumulation and determining concentrations of contaminants in biological tissues are best employed in conjunction with analysis of other environmental media (e.g., water, suspended particulate material, or sediment). Together these provide complementary lines of field evidence indicative of complexities that affect the exposures of organisms to contaminants. While tissue analysis is not universally suitable as a measure of exposure for all contaminants in all organisms or all circumstances, it does have important advantages when properly used: 1. Concentrations in tissues may be more responsive to environmental contamination than concentrations in water and/or sediments in some circumstances, providing a unique perspective on understanding exposures. 2. Measurements o...
Metal toxicity is affected by how organisms internally compartmentalize metals. This study compar... more Metal toxicity is affected by how organisms internally compartmentalize metals. This study compared the concentrations and intracellular distributions of Cd and Cu among hydropsychid caddisflies, Hydropsyche spp. and Arctopsyche grandis, and mayflies, Baetis spp. and Serratella tibialis, from contaminated sites in the upper Clark Fork river, Montana, and from an uncontaminated tributary (Blackfoot River). Bioaccumulation patterns exhibited species and metal specificity. Relative to uncontaminated samples, intracellular metal accumulation was greater in mayflies than in caddisflies. For example, Cd concentrations in the cytosol (soluble cytoplasm) were 7 - 13 (g/g in Serratella and Baetis and 0.4 - 2 (g/g in Hydropsyche and Arctopsyche. Cytosolic Cu concentrations were highest in Serratella (111 (g/g), and similar in Baetis, Hydropsyche and Arctopsyche (27 - 44 (g/g). The cytosol was a major accumulation site for Cd. Cadmium and Cu accumulation in the cytosol of Arctopsyche and Baetis was accompanied by a shift in the distribution of metal from “heat stable” (metal binding) to “heat denatured” (essential) proteins. The relatively high intracellular metal concentrations in Serratella and Baetis are supportive evidence of the reported metal sensitivity of mayflies. Species - specific toxicity may be further modified by how excess metal is partitioned among cytosolic ligands
Sixteen years ago, in October 2003, San Francisco Estuary and Watershed Science (SFEWS) published... more Sixteen years ago, in October 2003, San Francisco Estuary and Watershed Science (SFEWS) published its first article. An anniversary like this is a good time to remind ourselves of our history, and to ask if the journal is living up to the goals we set in 2003. And if so, are those goals consistent with today’s needs? In 2004, CDL’s eScholarship Publishing Group counted an average of 254 requests per month for SFEWS online articles. In 2010, that increased to 1,232 requests per month, and in 2014 to 1,764 per month. In the first 10 months of 2019, 4,420 articles were requested per month. Downloads have been consistently 35% to 40% of requests. Taking data from 2014 through 2017, the search engine Scopus’ CiteScore for SFEWS increased from 0.32 to 1.64; its rank is 82nd of 203 journals in the Water Science and Technology category for 2018, a remarkable climb from being ranked 120 of 179 in 2014. SFEWS is ranked fifth among 53 open access journals in the aquatic sciences, according to ...
Reproduction and condition of Potamocorbula amurensis were compared with cadmium concentration in... more Reproduction and condition of Potamocorbula amurensis were compared with cadmium concentration in the tissues of individual P. amurensis from five stations in northern San Francisco Bay to determine if either parameter could be used to assess ecosystem effects of trace metal contaminants. There is a gradient in cadmium content (ug/animal) and concentration (ng/g dry tissue) in tissues of clams which follows the freshwater gradient, with the freshest stations having the highest levels of cadmium contamination. Condition decreases with increasing cadmium content; animals from Honker Bay and Chipps Island have the highest cadmium content and lowest condition and those from San Pablo Bay have the lowest cadmium levels and highest condition. Synchrony in spawning was similarly related to cadmium content; animals with the highest cadmium concentration have asynchronous spawning. Asynchrony is potentially deleterious to organisms which depend on external fertilization, and thus may indicate that the reproductive success of other organisms in Suisun and San Pablo Bays may be harmed. The number of reproductive cycles, timing of reproduction, speed with which animals regain weight after spawning, and amount of weight gained during spawning, are most strongly related to food availability. Introduction The ecosystem effects of trace contaminants are the subject of ongoing discussions within San Francisco Bay regulatory agencies. Water-quality standards for all trace contaminants will be established within the next few years, and will be based on the ecological effects of each of the metals. Water-quality standards are established after preliminary standards are published, reviewed by the public, modified, and then subjected to further review. These regulatory processes will take several years to complete and the decisions will be aided by data describing the ecological effects of these contaminants. Trace-metal concentrations in San Francisco Bay are presently being assessed by analyzing the water column and the sediment, by doing bioassay tests on specific organisms, and by studying tissue burdens in some species. Although the ultimate goal of these studies is to determine what level of contamination results in harmful effects to the ecosystem, none of these approaches directly measures the effect of contaminants on the ecosystem. The major reason that direct measures of ecosystem effects have not been made is that the complexity of ecological processes can hide correlations between organism, population, or community changes and trace element concentrations. Some of this complexity is reflected in the way in which contaminants can affect animals and the communities in which they live. Chemical-biological interactions at the molecular level within an organism can influence developmental stages resulting in reproductive abnormalities, toxicity and adaptation due to changes in metabolic processes, and cellular damage due to effects on mitotic processes. At the organism level, contaminant stress can be seen with changes in physiology, behavior, reproductive success, larval success, and rates of parasitism and disease. At the more complex population level, changes in mortality, recruitment, biomass, production, and the structure of age and size classes are all possible effects of contaminants. At the community level, contaminant exposure may result in changes in species diversity, species composition, secondary production, and biomass. However, environmental stress, eg. osmotic and thermal extremes, can also cause many of the same effects. Thus, if ecosystem effects of contaminants are to be measured, it is necessary to examine selected parameters in a manner in which environmental and contaminant stresses can be separated. This report is the first step in looking at ecosystem effects of trace elements. Two life history parameters, reproductive periodicity and condition (change in tissue weight for a specific size of animal) of one species, Potamocorbula amurensis, are examined within a reach of San Francisco Bay that has a known trace metal concentration gradient (Brown and Luoma 1995). The contaminants within this gradient appear to originate with the freshwater inflow, i.e. the affected these parameters in the vicinity of our four upstream stations (figs. 3 and 4). Until 1986 the northern estuary had a late summer to early fall phytoplankton bloom (fig. 5). The cessation of this annual phytoplankton bloom since 1986 coincided with the introduction of Potamocorbula amurensis and it is believed that the lack of a phytoplankton bloom is due to over grazing by this filter feeder (Alpine and Cloern 1992). Therefore the major sources of food for P. amurensis, a filter feeder, are a combination of riverborne detritus and river derived phytoplankton in addition to locally grown phytoplankton, which never reaches high biomass levels. Each of these sources has a different seasonal and interannual pattern (fig. 6). The riverborne detritus is richest in non-refractory carbon at the beginning, not the peak, of the freshwater runoff during each year (Hagerand Schemel 1996) and was, no doubt, quite high in early 1993 when the drought ended. River chlorophyll a peaks in late spring and summer, but its transport into the bay is dependent on the amount and timing of freshwater runoff, so its quantity and seasonality vary between years. Growth rates of locally derived phytoplankton are dependent on light availability (Cloern 1987) and in this part of the estuary the growth rates usually peak in summer and fall. Summary of Contaminant and Condition Data Both cadmium content (jig in a 15mm animal, fig. 7) and concentration (|ig/g dry tissue, fig. 8) show a down-bay gradient with highest values seen in Honker Bay animals and the lowest values seen in San Pablo Bay animals (Brown and Luoma, written commun., 1996). Annual mean cadmium content was highest in 1993 in animals from the three upstream stations, showed little annual variation in Carquinez Strait animals, and was lowest in 1993 in San Pablo Bay animals (fig. 9). Condition for P. amurensis was generally higher at the down bay stations than at the freshest stations (fig. 10). Annual mean condition (fig. 11) was highest in animals from the seaward stations, San Pablo Bay and Carquinez Straits, and lowest in animals from Honker Bay. Methods Collection Methods To determine the reproductive pattern and gonadal development of P. amurensis, monthly samples were collected from the four channel stations and one shallow station for a period of 47 months, from January 1991 to December 1994. Animals representative of the size range present at each site were collected on the United States Geological Survey (USGS) research vessel Polaris with a Van Veen grab (0.05 m2) and rinsed through a 0.5 mm sieve, and preserved in 10 percent buffered formalin. Fifteen clams were examined for reproductive condition during 1991 for each sampling date and station and 10 clams were examined for each sampling date and station for the remaining years. There were several periods at all stations when no clams were found (table 2) and some periods when the sample size was reduced due to tissue damage during histological preparation. Reproductive Tissue Preparation Clam tissue was prepared and thin-sectioned by Bay Histology (San Rafael, California). The visceral mass of each clam was removed, stored in 70 percent ethyl alcohol, and then prepared using standard histological techniques: tissues were dehydrated in a graded series of alcohol, cleared in toluene (twice for one hour each), and infiltrated in a saturated solution of toluene and Paraplast for one hour, and two changes of melted Tissuemat for one hour each. Samples were then embedded in Paraplast in a vacuum chamber. The embedded samples were thin sectioned (10 Hm) using a microtome and then stained with Harris' hematoxylin and eosin. The stained thin sections were examined with a light microscope. Each specimen was characterized by size (length), sex, developmental stage and condition of the gonads thus allowing each specimen to be placed in one of five qualitative classes of gonadal development. Categories of Gonadal Development (Adapted from Rosenblum 1981) Female Gonads: Inactive Phase. Sex may be difficult or impossible to determine. Small ovocytes occur at the periphery of alveoli. A round nucleus in the ovocyte, encircled by an irregularly shaped cytoplasm, contains a conspicuous nucleolus. Follicle cells completely imbed the ovocytes and may fill the lumina of alveoli. Active Phase. Definite qualitative and quantitative changes in the gonads occur. Enlarging ovocytes grow between follicle cells towards the centers of alveoli. The ovocytes may be subconical, hemispherical, or cylindrical in shape, are rounded at the apices, and have broad cytoplasmic bases attaching them to the walls of the alveolus. Ripe Phase. Ovocytes appear as round cells in the lumina of the alveoli as if free of attachment to the basal membrane, but attachment is via a slender stalk. The nuclei of the largest ovocytes contain amphinucleoli, each consisting of an almost transparent nucleolus and a small opaque nucleolus membrane in cross section. The large ovocytes that fill the lumina are generally more numerous than the less-developed ovocytes. Partially Spawned Phase. Gonadal tissues contain a few ripe ovocytes. Small ovocytes are imbedded in follicle cells at the periphery of an empty alveolus. Many alveoli are devoid of ripe
Fine-grained, oxidized, surface sediments and two benthic bivalves (Corbi cul a sp., a suspension... more Fine-grained, oxidized, surface sediments and two benthic bivalves (Corbi cul a sp., a suspension-feeding freshwater clam, and Macoma balthica, a deposit-feeding brackish water clam) were used to examine spatial distributions of selenium within San Francisco Bay and the Sacramento/San Joaquin River Delta and to compare riverine with local inputs of biologically available selenium to this large, complex, urbanized estuary. Selenium concentrations in Corbicula were elevated in the western Delta and northern reach of San Francisco Bay compared to concentrations in Corbicula from river systems not enriched in selenium. Biologically available selenium did not appear to enter the southern Delta or northern reach of the Bay from the San Joaquin River, a possible source, in levels that could measurably influence bioaccumulation by Corbicula. Selenium concentrations in Macoma b a 1t h i c a also were elevated in southern South San Francisco Bay and near the western edge of Suisun Bay.
A preliminary study for the period February"July 1983 was completed in Suisun Bay, a shallow emba... more A preliminary study for the period February"July 1983 was completed in Suisun Bay, a shallow embayment of the San Francisco Bay system, California, to determine characteristic heavy metal concentrations present in sediments and organisms (Corbicula clams). Preliminary results show that the sediments of the study area are typical of other San Francisco Bay study sites. Sediments range from coarse sands to fine silt-clays and are enriched in manganese, with concentrations ranging from 24 to 818 M8/S (micrograms per gram), and are low in total organic carbon, with values ranging from 0.014-to 1.62-percent carbon. Iron is moderately enriched with acid-extractable iron concentrations of 162 to 3,521 |Jg/g. Concentrations of silver, zinc, lead, and cadmium measured in sediments between April and July are reported. Other San Francisco Bay studies have shown that pulses of increased concentrations occur during autumn and winter, a sampling period not covered in this data set. Lead concentrations range from 24 to 59 Mg/g. Cadmium concentrations range from less than 0.05 to 0.63 M8/S-Acidextractable copper concentrations range from 1.3 to 32.6 M8/8-Because of the paucity of data to date, interpretations separating physical and chemical influences on concentrations are not yet complete. Clam-tissue burdens for silver and zinc are similar to those found in Corbicula from pristine areas. Silver concentrations range from 61 to 332 nanograms per gram, and zinc ranges from 110 to 349 Mg/g. Copper concentrations range from 41 to 155 Mg/g. Cadmium levels range from 0.3 to 5.6 pg/g in Corbicula tissues.
^ The impacts of trace contaminants in aquatic environments cannot be assessed realistically with... more ^ The impacts of trace contaminants in aquatic environments cannot be assessed realistically without a greater understanding of the factors controlling the biological availability of the concentrated pool of metals associated with sediments. It has been established that direct uptake of (at least some) trace metals from sediments contributes to metal concentrations in benthic organisms. Important controls on metal uptake from sediment are the concentration of the exposure, the partitioning of the metals among components of the sediment, and the redox potential of the sediment. Important problems in ecology, physiology, geochemistry and biogeochemistry remain unresolved, however, and a concentrated interdisciplinary research effort will be necessary before a complete understanding of the fate and impact of sediment-bound metals will be possible.
The environmental dynamics of mercury were studied in Ala Wai Canal, a small Hawaiian estuary. Th... more The environmental dynamics of mercury were studied in Ala Wai Canal, a small Hawaiian estuary. Three indicator species were used in the study-the detritus feeding PoJ.i~haete Nereis succinea and shrimp Palaemon debilis and the predc.ceous decapod Thalamita crenata. The study employed laboratory experiments, utilizing 203-HgC12, and analyses of total mercury concentrations in sediment and biota samples collected periodically from the estuary. The two detritus feeders concentrated dissolved 203-Hg from 160 to 310 times over the concentration in seawater. Reduced salinity inhibited 203-Hg uptake by the worm but had little effect on uptake by the shrimp. Dissolved organic material also reduced 203-Hg accumulation. Little 203-Hg was accumulated from labelled estuarine sediment by either species-the steady state concentrations of 203-Hg in the animals ranged from only 0.25% to 1.5% of the concentration in the sediment. However, 203-Hg bound to sediment originating from urban street runoff was more available to both species than was 203-Hg bound to estuarine sediment. The availability of 203-Hg from runoff sediment declined as the sediment aged in seawater. Net loss of mercury occurred by way of two mono-exponential processes in both organisms and was slow relative to net accumulation. Total mercury analyses illustrated that mercury concentrations in sediment in Ala Wai Canal showed no obvious pattern of temporal variation. However, there was an obvious decrease in total mercury in the two detritus feeders between the rainy season and the dry summer months. Samples of~. debilis were collected at five day intervals during the rainy season. The equations describing accumulation and
Uptake from food and water and loss of 203 HgCl2were studied in two detritus feeders, the polyaha... more Uptake from food and water and loss of 203 HgCl2were studied in two detritus feeders, the polyahaete Nereis succinea and the shrimp Palaemon debilis, from a small Hawaiian estuary. During 1973 to 1974, total meraul'y analyses were also aonduated on sediment and biota samples aoUeated from the estuary. Detritus feeders aonaentrated dissolved 203Hg from 160 to 310 times over the aonaentration in sea water. LitUe 203 Hg was aaaumu lated from labelled estuarine sediment; the steady state aonaentration of 203Hg in the animals was 0.0025 to 0.015 times the aonaentration in the sediment the animals ingested. Net exaretion of 203 Hg was slow relative to aaaumulation in both spea-ies. The total meraul'y aontent of shrimp and woms ao l leated from the estuary sh01JJed a temporal pattern of variation. Samples of shrimp aoUeated at five day intervals were used, with a mathematiaal desaripi;ion of the aaaumulation and loss of metal by the shrimp to simulate biotia meraul'y dynamias in the estuary. The simulation showed that merau;py leve ls in shrimp in the Ala Wai Canal 1JJere never at steady state over the 1973-74 sampling period, and indiaated the most important sourae of biologiaally available meraU!'Y in the estuary was some inorgania, solute form of the metal.
A field and laboratory study of hibernation in, Zapus prinaeps was■ conducted.-Males gained weigh... more A field and laboratory study of hibernation in, Zapus prinaeps was■ conducted.-Males gained weight more ■ gradually, and reached a higher ■ weight peak than,female Z. pvinoeps. Hibernation was preceded in all animals by a period of lethargy and weight loss during which body temperatures were very 'labile.. Torpor was easily induced during the, summer by removing either food or.water from Zapus at ,any temperatures' below 220, Arousal from induced torpor during the summer,did not occur at. temperatures below TOO,, probably due to a lack of a suffix cient amount.of brown fat.-Animals kept at,constant temperature (3±1C) in 24 hours of light per day hibernated two,to three weeks later, than animals caged puts.ide.. The characteristics' of hibernation/ in Z. pvbnoeps appear to place it between the larger obligatory hibernators and the-smaller mammals that hibernate.. * .Differences between percentages of initial weight gained per day in the two groups were not significant (p-c.075) (Lentner, 1968).
Proceedings of the Water Environment Federation, 2009
ABSTRACT Since 2004, a group of over 20 stakeholders have been implementing a comprehensive progr... more ABSTRACT Since 2004, a group of over 20 stakeholders have been implementing a comprehensive program to address sources of nitrogen and selenium in the Newport Bay watershed in Orange County, California. The collaborative, stakeholder driven effort, the Nitrogen and Selenium Management Program (NSMP), included the development of a site-specific objective (SSO) for selenium. A tissue-based SSO has been developed that represents a unique shift from traditional water column based standards. The SSO developed through the NSMP is an example of a how a collaborative, stakeholder driven effort provided an opportunity for federal, state, regional, and local agencies to work with the regulated community and environmental non-profit organizations in order to develop a comprehensive, progressive, and unique approach to water quality management.
Ecological Assessment of Selenium in the Aquatic Environment, 2010
To date there has been no clear guidance for assessing the potential environmental effects and im... more To date there has been no clear guidance for assessing the potential environmental effects and impacts of selenium (Se) contamination; such activities have been highly site-specific. A Society of Environmental Toxicology and Chemistry (SETAC) Pellston Workshop held February 22-28, 2009, which involved a multidisciplinary and international group of scientists, managers and policymakers, established the present state of the science and provided globally-applicable guidance for assessing and managing the environmental effects of Se. Key information from the SETAC Pellston includes: traditional methods for predicting toxicity on the basis of exposure to dissolved concentrations do not work for Se; enrichment functions can be used to predict Se bioaccumulation at the base of food webs; uptake by individual species and in steps of the food web can be described by a trophic transfer function; Se partitioning is unique among metal and metalloid contaminants and requires site-specific risk assessments to a much greater extent than most other contaminants.
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