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Keywords = tubificid density

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15 pages, 4360 KiB  
Article
The Effect of Tubificid Bioturbation on Vertical Water Exchange across the Sediment–Water Interface
by Ruichen Mao, Jintao Wu, Xin Qin, Chi Ma, Jinxi Song, Dandong Cheng, Haotian Sun and Mingyue Li
Water 2020, 12(12), 3467; https://doi.org/10.3390/w12123467 - 10 Dec 2020
Cited by 8 | Viewed by 3426
Abstract
The bioturbation activity of macroinvertebrates can affect the level of water exchange across the sediment–water interface. The impact of tubificid worm with different densities on the vertical water exchange at the sediment–water interface was investigated based on laboratory flume experiments. Vertical water fluxes, [...] Read more.
The bioturbation activity of macroinvertebrates can affect the level of water exchange across the sediment–water interface. The impact of tubificid worm with different densities on the vertical water exchange at the sediment–water interface was investigated based on laboratory flume experiments. Vertical water fluxes, as well as physiochemical parameters, were measured at seven-day intervals, and the maximum penetration depths were obtained by dye injection before and after the tubificid bioturbation experiment, respectively. The bioturbation effects can be summarized in two aspects: (1) when the density was less than (or equal to) 20 individual/10 cm2, the volume of vertical water exchange positively correlated with the tubificid bioturbation. Once the density exceeded (or equaled) 25 individual/10 cm2, the vertical water flux decreased with increasing tubificid bioturbation. After 14 to 21 days, a negative correlation was identified between the bioturbation and the vertical water flux under all biological densities. (2) The maximum depth that the surface water can penetrate the sediment increased with increasing tubificid density. These results revealed that the vertical water was closely related to the biological density. The study has certain reference significance to understanding the spatiotemporal heterogeneity of hyporheic water exchange on a local scale. Full article
(This article belongs to the Special Issue Advances in Environmental Hydraulics)
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15 pages, 700 KiB  
Article
Effect Thresholds of Metals in Stream Sediments Based on In Situ Oligochaete Communities
by Régis Vivien, Carmen Casado-Martínez, Michel Lafont and Benoit J.D. Ferrari
Environments 2020, 7(4), 31; https://doi.org/10.3390/environments7040031 - 13 Apr 2020
Cited by 8 | Viewed by 4907
Abstract
Aquatic oligochaetes, comprising a large number of species showing various degrees of resistance to chemical pollution, are recognized as valuable bioindicators of sediments’ quality. In the Geneva area (Switzerland), oligochaete tools were previously tested for assessing the biological quality of stream sediments, and [...] Read more.
Aquatic oligochaetes, comprising a large number of species showing various degrees of resistance to chemical pollution, are recognized as valuable bioindicators of sediments’ quality. In the Geneva area (Switzerland), oligochaete tools were previously tested for assessing the biological quality of stream sediments, and effect thresholds of combined metals (quotients) in sediments were defined. The aims of the present study were to update this previous work with new data acquired in different cantons of Switzerland and to establish effect thresholds on oligochaete communities for individual metals and for combined metals. The oligochaete metrics “Oligochaete index of sediment bioindication (IOBS)”, “oligochaete density” and “percentage of tubificids without hair setae” proved pertinent for assessing the effects of metals and organic matter in sediments. We established a threshold effect level (TELoligo) and probable effect level (PELoligo) for eight metals in sediments (Cr, Ni, Zn, Cu, Pb, Cd, Hg and As) as well as a probable effect level for these metals combined (mPELoligo-Q). These thresholds could be used directly to screen for alteration of in situ communities restricted to sediments and/or for establishing sediment quality standards based on a combination of different biological and ecotoxicological tools. Full article
(This article belongs to the Special Issue New Insights into Impacts of Toxic Metals in Aquatic Environments)
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