Effect of Body Size on Methylmercury Concentrations in Shoreline Spiders: Implications for Their Use as Sentinels

Abstract

Shoreline spiders have been proposed as sentinels to monitor aquatic contaminants including methylmercury (MeHg). The present study examined the effect of spider body size on MeHg concentrations in shoreline spiders. We collected 6 taxa of spiders belonging to 4 families (orb-weavers [Araneidae], long-jawed orb weavers [Tetragnathidae: Tetragnatha sp.], jumping spiders [Salticidae], and wolf spiders [Lycosidae: Pardosa sp., Rabidosa sp., and Schizocosa sp.]) from the shorelines of 14 human-made ponds at the Lyndon B. Johnson National Grasslands in north Texas (USA). As a proxy for body size, we measured leg length (tibia + patella) of each spider. Spider taxa differed by 3-fold in mean MeHg concentration, and MeHg concentrations in 4 of 6 spider taxa increased significantly with leg length. The present study is the first to demonstrate that shoreline spider MeHg concentrations increase as a function of spider body size. Because spider size may account for some within-taxa variation in MeHg concentrations, future studies that utilize spiders as sentinels of aquatic contamination by MeHg or other biomagnifying contaminants should take spider size into account.

Use of Riparian Spiders as Sentinels of Persistent and Bioavailable Chemical Contaminants in Aquatic Ecosystems: A Review

“…The effect of riparian spider age/size has only been examined for metals. Negative correlations between Hg and size (Pennuto & Smith, 2015) and Cd and size/age class (Ramirez et al, 2011) have been reported, whereas positive correlations were reported between Hg and size in four riparian spider taxa (Hannappel et al, 2021). Hannappel et al (2021) reported a lack of correlation between Hg and size in two riparian spider taxa, whereas Ramirez et al (2011) reported a lack of correlation between size and Zn, Cu, and Cr in riparian spider tissues.…”

“…Negative correlations between Hg and size (Pennuto & Smith, 2015) and Cd and size/age class (Ramirez et al, 2011) have been reported, whereas positive correlations were reported between Hg and size in four riparian spider taxa (Hannappel et al, 2021). Hannappel et al (2021) reported a lack of correlation between Hg and size in two riparian spider taxa, whereas Ramirez et al (2011) reported a lack of correlation between size and Zn, Cu, and Cr in riparian spider tissues. Although age‐related bioaccumulation occurs in other sentinels (e.g., fish; Wiener et al, 2003), its importance in riparian spiders has not been well established.…”

“…Twelve studies have statistically assessed taxonomic differences in contaminant concentrations (Abeysinghe et al, 2017; Bartrons et al, 2015; Beaubien et al, 2020; Hannappel et al, 2021; Hendrickx et al, 2004; Kraus et al, 2017; Ortega‐Rodriguez et al, 2019; Sullivan et al, 2016; Tavshunsky et al, 2017; Tojal et al, 2002; Walters et al, 2008, 2010; Walters et al, 2018). Among these, more than 80% (10 out of 12 studies) reported taxonomic differences in contaminant accumulation.…”

“…Factors in column 1 are defined and reviewed in the text and in Supporting Information, Table S3. 1, Anderson et al, 1973; 2, Maelfait and Hendrickx, 1998; 3, Torres and Johnson, 2001; 4, Du Laing et al, 2002; 5, Tojal et al, 2002; 6, Hendrickx et al, 2004; 7, Cristol et al, 2008; 8, Schipper et al, 2008; 9, Walters et al, 2008; 10, Zhang et al, 2009; 11, Walters et al, 2010; 12, Zhang et al, 2010; 13, Raikow et al, 2011; 14, Ramirez et al, 2011; 15, Wyman et al, 2011; 16, Edmonds et al, 2012; 17, Tsui et al, 2012; 18, Otter et al, 2013; 19, Tweedy et al, 2013; 20, Wang et al, 2013; 21, Marr et al, 2014; 22, Speir et al, 2014; 23, Bartrons et al, 2015; 24, Gann et al, 2015; 25, Kwon et al, 2015; 26, Ortiz Jr. et al, 2015; 27, Pennuto and Smith, 2015; 28, Alberts and Sullivan, 2016; 29, Chaves‐Ulloa et al, 2016; 30, Kim and Kim, 2016; 31, Laws et al, 2016; 32, Moy et al, 2016; 33, Sullivan et al, 2016; 34, Abeysinghe et al, 2017; 35, Hepp et al, 2017; 36, Kraus et al, 2017; 37, Tavshunsky et al, 2017; 38, Archer et al, 2018; 39, Howie et al, 2018; 40, Richmond et al, 2018; 41, Walters et al, 2018; 42, Beaubien et al, 2019; 43, Ortega‐Rodriguez et al, 2019; 44, Qiu et al, 2019; 45, Rodenhouse et al, 2019; 46, Beaubien et al, 2020; 47, Bergmann and Graça, 2020; 48, Gerson et al, 2020; 49, Koch et al, 2020; 50, Naslund et al, 2020; 51, Cetinić et al 2021; 52, Hannappel et al, 2021; 53, Kraus et al, 2021; 54, Ku et al, 2021; 55, Previšić et al, 2021.…”

Mud Dauber Nests as Sources of Spiders in Mercury Monitoring Studies

“…For example, the distance that mud daubers forage from their nests is unknown, and until this is resolved, using spiders from mud dauber nests to identify highly localized areas of contamination could be problematic. In addition, mud daubers may prefer smaller spiders (Coville 1987), which have relatively low levels of Hg contamination (Hannappel et al 2021), and mud daubers are known to be selective foragers (e.g., Rau 1935; Muma and Jeffers 1945). For example, although we have observed large populations of Tetragnathidae along the Trinity River, in the present study we found few Tetragnathid spiders in mud dauber nests.…”