2012
Tsui, Martin Tsz Ki; Blum, Joel D.; Kwon, Sae Yun; Finlay, Jacques C.; Balogh, Steven J.; Nollet, Yabing H.
Sources and transfers of methylmercury in adjacent river and forest food webs Journal Article
In: Environmental Science & Technology, vol. 46, no. 20, pp. 10957–10964, 2012.
Abstract | Links | BibTeX | Tags: forest food web, Methylmercury, river food web
@article{Tsui2012,
title = {Sources and transfers of methylmercury in adjacent river and forest food webs},
author = {Martin Tsz Ki Tsui and Joel D. Blum and Sae Yun Kwon and Jacques C. Finlay and Steven J. Balogh and Yabing H. Nollet},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Tsui_2012_EnvirScieTech.pdf},
doi = {10.1021/es3019836},
year = {2012},
date = {2012-10-04},
journal = {Environmental Science & Technology},
volume = {46},
number = {20},
pages = {10957–10964},
abstract = {Nearly all ecosystems are contaminated with highly toxic methylmercury (MeHg), but the specific sources and pathways leading to the uptake of MeHg within and among food webs are not well understood. In this study, we report stable mercury (Hg) isotope compositions in food webs in a river and an adjacent forest in northern California and demonstrate the utility of Hg isotopes for studying MeHg sources and cross-habitat transfers. We observed large differences in both δ202Hg (mass-dependent fractionation) and Δ199Hg (mass-independent fractionation) within both food webs. The majority of isotopic variation within each food web could be accounted for by differing proportions of inorganic Hg [Hg(II)] and MeHg along food chains. We estimated mean isotope values of Hg(II) and MeHg in each habitat and found a large difference in δ202Hg between Hg(II) and MeHg (∼2.7‰) in the forest but not in the river (∼0.25‰). This is consistent with in situ Hg(II) methylation in the study river but suggests Hg(II) methylation may not be important in the forest. In fact, the similarity in δ202Hg between MeHg in forest food webs and Hg(II) in precipitation suggests that MeHg in forest food webs may be derived from atmospheric sources (e.g., rainfall, fog). Utilizing contrasting δ202Hg values between MeHg in river food webs (−1.0‰) and MeHg in forest food webs (+0.7‰), we estimate with a two-source mixing model that ∼55% of MeHg in two riparian spiders is derived from riverine sources while ∼45% of MeHg originates from terrestrial sources. Thus, stable Hg isotopes can provide new information on subtle differences in sources of MeHg and trace MeHg transfers within and among food webs in natural ecosystems.},
keywords = {forest food web, Methylmercury, river food web},
pubstate = {published},
tppubtype = {article}
}
Nearly all ecosystems are contaminated with highly toxic methylmercury (MeHg), but the specific sources and pathways leading to the uptake of MeHg within and among food webs are not well understood. In this study, we report stable mercury (Hg) isotope compositions in food webs in a river and an adjacent forest in northern California and demonstrate the utility of Hg isotopes for studying MeHg sources and cross-habitat transfers. We observed large differences in both δ202Hg (mass-dependent fractionation) and Δ199Hg (mass-independent fractionation) within both food webs. The majority of isotopic variation within each food web could be accounted for by differing proportions of inorganic Hg [Hg(II)] and MeHg along food chains. We estimated mean isotope values of Hg(II) and MeHg in each habitat and found a large difference in δ202Hg between Hg(II) and MeHg (∼2.7‰) in the forest but not in the river (∼0.25‰). This is consistent with in situ Hg(II) methylation in the study river but suggests Hg(II) methylation may not be important in the forest. In fact, the similarity in δ202Hg between MeHg in forest food webs and Hg(II) in precipitation suggests that MeHg in forest food webs may be derived from atmospheric sources (e.g., rainfall, fog). Utilizing contrasting δ202Hg values between MeHg in river food webs (−1.0‰) and MeHg in forest food webs (+0.7‰), we estimate with a two-source mixing model that ∼55% of MeHg in two riparian spiders is derived from riverine sources while ∼45% of MeHg originates from terrestrial sources. Thus, stable Hg isotopes can provide new information on subtle differences in sources of MeHg and trace MeHg transfers within and among food webs in natural ecosystems.
2004
Suttle, Kenwyn B.; Power, Mary E.; Levine, Jonathan M.; McNeely, Camille
How Fine Sediment in Riverbeds Impairs Growth and Survival of Juvenile Salmonids Journal Article
In: Ecological Applications, vol. 14, no. 4, pp. 969-974, 2004.
Abstract | Links | BibTeX | Tags: fine sediment, Oncorhynchus mykiss, Pacific salmonids, parr, river food web, sedimentation, steelhead trout
@article{Suttle2004,
title = {How Fine Sediment in Riverbeds Impairs Growth and Survival of Juvenile Salmonids},
author = {Kenwyn B. Suttle and Mary E. Power and Jonathan M. Levine and Camille McNeely},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/How-Fine-Sediment-in-Riverbeds-Impairs-Growth-and-Survival-of-Juvenile-Salmonids_Suttle_Power_Levine_McNeely.pdf},
doi = {http://dx.doi.org/10.1890/03-5190},
year = {2004},
date = {2004-08-01},
journal = {Ecological Applications},
volume = {14},
number = {4},
pages = {969-974},
abstract = {Although excessive loading of fine sediments into rivers is well known to degrade salmonid spawning habitat, its effects on rearing juveniles have been unclear. We experimentally manipulated fine bed sediment in a northern California river and examined responses of juvenile salmonids and the food webs supporting them. Increasing concentrations of deposited fine sediment decreased growth and survival of juvenile steelhead trout. These declines were associated with a shift in invertebrates toward burrowing taxa unavailable as prey and with increased steelhead activity and injury at higher levels of fine sediment. The linear relationship between deposited fine sediment and juvenile steelhead growth suggests that there is no threshold below which exacerbation of fine-sediment delivery and storage in gravel bedded rivers will be harmless, but also that any reduction could produce immediate benefits for salmonid restoration.},
keywords = {fine sediment, Oncorhynchus mykiss, Pacific salmonids, parr, river food web, sedimentation, steelhead trout},
pubstate = {published},
tppubtype = {article}
}
Although excessive loading of fine sediments into rivers is well known to degrade salmonid spawning habitat, its effects on rearing juveniles have been unclear. We experimentally manipulated fine bed sediment in a northern California river and examined responses of juvenile salmonids and the food webs supporting them. Increasing concentrations of deposited fine sediment decreased growth and survival of juvenile steelhead trout. These declines were associated with a shift in invertebrates toward burrowing taxa unavailable as prey and with increased steelhead activity and injury at higher levels of fine sediment. The linear relationship between deposited fine sediment and juvenile steelhead growth suggests that there is no threshold below which exacerbation of fine-sediment delivery and storage in gravel bedded rivers will be harmless, but also that any reduction could produce immediate benefits for salmonid restoration.