Mercury accumulation by lower trophic-level organisms in lentic systems within the Guadalupe River watershed, California

Kuwabara, James S.; Topping, Brent R.; Moon, Gerald E.; Husby, Peter; Lincoff, Andrew; Carter, James L.; Croteau, Marie‐Noële

doi:10.3133/sir20055037

Cited by 14 publications

(16 citation statements)

References 11 publications

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“…In contrast, reservoirs and lakes in the Guadalupe River watershed, in close proximity to the New Almaden Mercury Mines in California, show hypolimnetic production of MeHg as a major source of MeHg to food webs both within the lake or reservoir as well as those downstream. Log BAFs calculated for unfiltered aqueous MeHg and zooplankton in CFWR and the Guadalupe watershed reservoirs (Kuwabara et al 2005) were similar, which suggests broadly similar processes of enrichment from raw aqueous MeHg into phytoplankton and then zooplankton, regardless of the source of MeHg. Thus, it is reasonable that a general management priority should be on identifying the source and reducing the quantity of aqueous MeHg that is initially accumulated at the base of reservoir food webs.…”

Section: Influence Of Trophic Pathway On Mehg Bioaccumulationmentioning

confidence: 72%

Influence of plankton mercury dynamics and trophic pathways on mercury concentrations of top predator fish of a mining-impacted reservoir

Stewart

Saiki

Kuwabara

et al. 2008

Can. J. Fish. Aquat. Sci.

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Physical and biogeochemical characteristics of the aquatic environment that affect growth dynamics of phytoplankton and the zooplankton communities that depend on them may also affect uptake of methylmercury (MeHg) into the pelagic food web of oligotrophic reservoirs. We evaluated changes in the quality and quantity of suspended particulate material, zooplankton taxonomy, and MeHg concentrations coincident with seasonal changes in water storage of a mining-impacted reservoir in northern California, USA. MeHg concentrations in bulk zooplankton increased from 4 ngÁg -1 at low water to 77 ± 6.1 ngÁg -1 at high water and were positively correlated with cladoceran biomass (r = 0.66) and negatively correlated with rotifer biomass (r = -0.65). Stable isotope analysis revealed overall higher MeHg concentrations in the pelagic-based food web relative to the benthic-based food web. Statistically similar patterns of trophic enrichment of MeHg (slopes) for the pelagic and benthic food webs and slightly higher MeHg concentrations in zooplankton than in benthic invertebrates suggest that the difference in MeHg bioaccumulation among trophic pathways is set at the base of the food webs. These results suggest an important role for plankton dynamics in driving the MeHg content of zooplankton and ultimately MeHg bioaccumulation in top predators in pelagic-based food webs.Résumé : Les caractéristiques physiques et biogéochimiques du milieu aquatique qui affectent la dynamique de la croissance du phytoplancton et les communautés zooplanctoniques qui en dépendent peuvent aussi influencer l'introduction de méthylmercure (MeHg) dans le réseau alimentaire pélagique des réservoirs oligotrophes. Nous déterminons les changements dans la qualité et la quantité des matières particulaires en suspension, dans la taxonomie du zooplancton et dans les concentrations de MeHg qui coïncident avec les changements saisonniers d'emmagasinement d'eau dans un réservoir affecté par des activités minières dans le nord de la Californie, É .-U. Les concentrations de MeHg dans le zooplancton global augmentent de 4 ngÁg -1 aux basses eaux à 77 ± 6,1 ngÁg -1 aux hautes eaux et elles sont en corrélation positive avec la biomasse des cladocères (r = 0,66) et en corrélation négative avec la biomasse des rotifères (r = -0,65). Une analyse des isotopes stables indique des concentrations globalement plus élevées de MeHg dans le réseau alimentaire pélagique que dans le réseau alimentaire benthique. Les patrons statistiquement semblables d'enrichissement trophique de MeHg (pentes) dans les réseaux alimentaires pélagiques et benthiques et des concentrations légèrement supérieures de MeHg dans le zooplancton par rapport aux invertébrés benthiques font penser que la différence de bioconcentration de MeHg entre les voies trophiques s'établit dès la base des réseaux alimentaires. Ces résultats indiquent un rôle important joué par la dynamique du plancton dans le contenu en MeHg du zooplanction et, en fin de compte, dans la bioconcentration de MeHg chez les prédate...

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Section: Influence Of Trophic Pathway On Mehg Bioaccumulationmentioning

confidence: 72%

Influence of plankton mercury dynamics and trophic pathways on mercury concentrations of top predator fish of a mining-impacted reservoir

Stewart

Saiki

Kuwabara

et al. 2008

Can. J. Fish. Aquat. Sci.

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“…We selected studies that minimized nonphytoplankton particulates. For example, Kuwabara et al (2005) found no detritus when they examined their samples microscopically. Laurier et al (2003) used nets to collect a size fraction (150 mm-1-mm fraction) that favored large biological material.…”

Section: Discussionmentioning

confidence: 99%

Role of phytoplankton in mercury cycling in the San Francisco Bay estuary

Luengen

Flegal

2009

Limnol. Oceanogr.

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To study the role of phytoplankton in mercury cycling, we measured methylmercury (MeHg) and total mercury (Hg T ) in surface waters during the spring 2003 phytoplankton bloom in San Francisco Bay. Conditions that described the peak of the bloom, the amount of sorbent, and decay of the bloom were summarized by principal component analysis (PCA). Multivariate analyses conducted with the PCA factors demonstrated that the bloom accounted for a significant (p 5 0.03) decrease in dissolved (,0.45 mm) MeHg. Dissolved MeHg was depleted to 0.026 pmol L 21 and was unaffected when chlorophyll a concentrations nearly tripled, indicating that bloom dilution could occur as a result of a limited amount of MeHg. The calculated algal MeHg concentration was 3-10 pmol g 21 (dry weight). As the bloom decayed, dissolved MeHg concentrations significantly (p 5 0.04) increased, likely due to MeHg remineralization from decaying phytoplankton and/or production in sediments. By creating suboxic conditions in surface sediments and stimulating microbial activity, decomposing phytoplankton could bolster MeHg production, a potential side effect of large blooms. Unlike dissolved MeHg, dissolved Hg T concentrations were not measurably altered by the bloom or decay factors. That difference corroborated previous culture studies in which phytoplankton actively accumulated MeHg, but not Hg T . As the bloom decayed, Hg T K d values significantly (p 5 0.012) increased, possibly because particles (i.e., phytoplankton) with low Hg T concentrations were lost from the water column. Based on the relationship between Hg T particulate concentrations and percent phytoplankton, the calculated algal Hg T concentration was ,0.5 nmol g 21 (dry weight).

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“…Kuwabara et al . [] found that neither zooplankton densities nor biomass correlated with phytoplankton densities or biovolumes in the study reservoirs, suggesting that the communities were not in equilibrium and thus that bioaccumulation factors should be measured at finer temporal and spatial scales.…”

Section: Discussionmentioning

confidence: 88%

“…These factors are similar to observations of others nationally [ Wiener et al ., ], although Kuwabara et al . [] found approximately fivefold increases in the study reservoirs. The four‐lake geometric mean BAF is 25% lower than the national average BAF determined by USEPA [] for small fish.…”

Section: Discussionmentioning

confidence: 89%

Evaluation of mercury cycling and hypolimnetic oxygenation in mercury-impacted seasonally stratified reservoirs in the Guadalupe River watershed, California

McCord¹,

Beutel

Dent

et al. 2016

Water Resour. Res.

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Surface water reservoirs trap inorganic mercury delivered from their watersheds, create conditions that convert inorganic mercury to highly toxic methylmercury (MeHg), and host sportfish in which MeHg bioaccumulates. The Santa Clara Valley Water District (District) actively manages and monitors four mercury‐impaired reservoirs that help to serve communities in South San Francisco Bay, California. The Guadalupe River watershed, which contains three of those reservoirs, also includes the New Almaden mercury‐mining district, the largest historic mercury producer in North America. Monthly vertical profiles of field measurements and grab samples in years 2011–2013 portray annual cycling of density stratification, dissolved oxygen (DO), and MeHg. Monitoring results highlight the role that hypolimnetic hypoxia plays in MeHg distribution in the water column, as well as the consistent, tight coupling between MeHg in ecological compartments (water, zooplankton, and bass) across the four reservoirs. Following the 2011–2013 monitoring period, the District designed and installed hypolimnetic oxygenation systems (HOS) in the four reservoirs in an effort to repress MeHg buildup in bottom waters and attain regulatory targets for MeHg in water and fish tissue. Initial HOS operation in Calero Reservoir in 2014 enhanced bottom water DO and depressed hypolimnetic buildup of MeHg, but did not substantially decrease mercury levels in zooplankton or small fish.

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Mercury accumulation by lower trophic-level organisms in lentic systems within the Guadalupe River watershed, California

Cited by 14 publications

References 11 publications

Influence of plankton mercury dynamics and trophic pathways on mercury concentrations of top predator fish of a mining-impacted reservoir

Influence of plankton mercury dynamics and trophic pathways on mercury concentrations of top predator fish of a mining-impacted reservoir

Role of phytoplankton in mercury cycling in the San Francisco Bay estuary

Evaluation of mercury cycling and hypolimnetic oxygenation in mercury-impacted seasonally stratified reservoirs in the Guadalupe River watershed, California

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