Exploring the use of nuclear alterations, motility and ecological guilds in epipelic diatoms as biomonitoring tools for water quality improvement in urban impacted lowland streams
Año: 2020 vol. 110
In this study we explored the use of less conventional diatom metrics (motility, nuclear abnormalities andecological guilds) to measure changes in diatom assemblages related to the transfer of epipelic communities fromurban impacted streams to less impacted sites. Three lowland streams in the Argentine Pampean plain wereselected, and two sites were established per stream for a total of six sites. Three sites were referenced as lowurban impact (LI), as they run through peri-urban areas, and three downstream sites were referenced as highimpact sites (HI), since they run through a dense urban area. Six germination trays filled with stream sedimentwere placed at each HI site, and three at each LI site, and left to be colonized for 30 days before transferring threetrays from the HI sites to their respective LI site upstream. Samples were collected at days 0, 15, 30 and 45 daysfrom each tray, and diatom species were identified and classified into ecological guilds. Motility variables weremeasure per individual of the genera Nitzschia (path length, velocity and maximum velocity) through videorecording. Also, the frequency of abnormal nuclear locations and nuclear membrane breakage were determined.Results showed that there were no significant differences in any motility metrics, while the nuclei variablesexhibited higher proportion of abnormally positioned nuclei and nuclear membrane breakage at the HI sites. Theproportion of nuclear membrane breakage decreased over time in the translocated assemblage, indicating that itcould be a sensitive indicator of water quality improvement, while the ecological guilds showed significantdifferences on the proportion of high profile and motile diatoms. The improvement in water quality produced asignificative increase in the proportion of the high profile guild in the translocated biofilm. Despite the motileforms being the dominant group, the water quality improvement allowed the high profile forms, to colonize thesubstrate. These results emphasize the possible use of the ecological guilds as a suitable indicator of waterquality improvement in Pampean streams, especially in nutrient rich environment. These tools can provide arapid assessment of diatom condition and could be considered supplementary to biomonitoring protocols inlowland streams.1. IntroductionDiatoms are commonly used as biological indicators to assess waterquality in rivers and streams, due to their sensitivity to a wide range ofenvironmental stresses (Van Dam et al., 1994; Kelly, 2003; Morin et al.,2016). Their use in water quality assessments is supported in their rapidresponse to changes in environmental conditions of both pollution increasesand habitat restoration success (Stevenson et al., 1999), theirgreat abundance in most lotic ecosystems (Blinn et al., 1980), and theirshort generational times (Rott, 1991). A major advantage of usingdiatoms in environmental studies is that diatoms can be used to investigatethe effects of toxic pollution at different levels of ecologicalorganization (community, population, and individual levels)(McCormick and Cairns, 1994; Debenest et al., 2013; Stevenson, 2014).Traditional metrics such as biovolume, cell density, relative abundance,indices (with special reference to indicator species), providesensitive and powerful tools for evaluating water quality changes (e.g.Rimet et al., 2009; Morin et al., 2010; Proia et al., 2011; Arini et al.,2012; Corcoll et al., 2012; Morin et al., 2012; Cochero et al., 2015). Lessconventional parameters, including behavioral, physiological and 5 June 2019; Received in revised form 6 November 2019; Accepted 18 November 2019⁎ Corresponding author.E-mail address: (M.M. Nicolosi Gelis).Ecological Indicators 110 (2020) 1059511470-160X/ © 2019 Elsevier Ltd. All rights reserved.T