Interactions\nbetween Lanthanum-Modified Bentonite\n(LMB) and Benthic Macroinvertebrates with Varied Bioturbation Modes

Lanthanum-Modified Bentonite (LMB) is widely used to\nmitigate endogenous\nphosphorus (P) in eutrophic lakes. Benthic macroinvertebrates coexisting\nwith LMB may potentially impact its distribution and P removal efficiency;\nhowever, research on the interaction between LMB and macroinvertebrates,\nespecially with different bioturbation patterns, is limited. Accordingly,\nthree prevalent benthic macroinvertebrate speciesBranchiura sowerbyi (BS), Chironomus\nflaviplumus (CF), and Radix swinhoei (RS), were selected for microcosm incubation experiments. Our findings\nindicate no substantial impact of macroinvertebrates on the overall\nP removal efficiency of LMB, although its vertical redistribution\nwas species-specific with BS > CF > RS. Although substantial\nBS bioturbation\nmay reduce LMB’s efficacy in removing P at the sediment–water\ninterface (SWI), it may enhance P retention capacity in deeper sediments.\nIn contrast, CF constructed transient holes and corridors in the surficial\nsediments, compromising the integrity of the LMB capping layer, while\nRS only occupied the SWI with minimal bioturbation of the LMB. As\nCF and RS primarily occupied the SWI, there was minimal impact on\nLMB’s P removal but with higher La concentrations in the overlying\nwater compared to BS. Crucially, LMB appeared to inhibit the growth\nand reproduction of both RS and CF and increased mortality. Although\nLa bioaccumulation was highest in BS, which also had the greatest\nability to disrupt the LMB capping layer, there was no significant\nadverse effect on its growth and survival.