Following publications have been announced by our Institute of Carbon Cycles. For further information please contact Dr. Bryce Van Dam, author and co-author of the publications:
Van Dam, B., Lopes, C., Zeller, M.A., Ribas-Ribas, M., Wang, H., & Thomas, H. (2021): Overstated Potential for Seagrass Meadows to Mitigate Coastal Ocean Acidification. Front. Mar. Sci. 8:729992, doi:10.3389/fmars.2021.729992
Abstract:
Ricart et al. (2021, R21) explored the potential for seagrass meadows to act as a buffer of coastal ocean acidification (OA). This work relied largely on sensor-based pH measurements during 29 separate instrument deployments along the California coast, arguing that (1) seagrass aerobic metabolism consistently enhances local pH, and that (2) this OA-amelioration can persist for lengths of up to 21 days. While pH was often greater in seagrass meadows than in adjacent unvegetated regions, we are concerned with the extent to which this is attributed to seagrass ecosystem metabolism, and the interpretation that this OA-amelioration is sustained over daily and tidal timescales. By incompletely considering alternative explanations for elevated pH, irrespective of seagrass productivity, R21 offers insufficient support of OA-mitigation as a reliable ecosystem service of seagrasses. We therefore see the authors‘ claim that seagrass ecosystems could be “leveraged as local management tools to mitigate the consequences of OA” as worthy of critical inspection.
Shi, W., Zhu, L., Van Dam, B., Smyth, A.R., Deng, J., Zhou, J., Pan, G., Yi, Q., Yu, J., & Qin, B. (2022): Wind induced algal migration manipulates sediment denitrification N-loss patterns in shallow Taihu Lake, China. Water Research, Volume 209, 2022, 117887, doi:10.1016/j.watres.2021.117887
Abstract:
Driven by winds, the distribution of algae is often noticeably patchy at kilometer scales in shallow lakes. The decomposition of the settled algal biomass may affect nitrogen (N) biogeochemical cycles and thereby N loss in sediments. In this study, we investigated sediment denitrification N-loss patterns along algal migration pathway in Taihu Lake, a shallow and eutrophic lake in China, and found that wind-induced algal migration in the overlying water manipulated the temporal and spatial patterns of denitrification N-loss in sediments. A N loss hotspot in sediments was created in the algae concentrated zone, where N loss was, however, temporarily inhibited during algal bloom seasons and generally exhibited a negative relationship with algal biomass. In the zone where algae have left, sediment N loss rate was relatively low and positively correlated with algal biomass. The decay of algal biomass generated organic carbon and created anoxia, favoring denitrification, while excessive algal biomass could deplete oxygen and inhibit nitrification, causing nitrate limitation for denitrification. Piecewise linear regression analysis indicated that algal biomass of Chl-a > 73.0 μg/L in the overlying water could inhibit denitrification N-loss in sediments. This study adds to our understanding of N biogeochemical cycles in shallow eutrophic lakes.