Elevated major ion concentrations inhibit larval mayfly growth and development

Abstract

Anthropogenic disturbances, including those from developing energy resources, can alter stream chemistry significantly by elevating total dissolved solids. Field studies have indicated that mayflies (Order Ephemeroptera) are particularly sensitive to high total dissolved solids. In the present study, the authors measured 20-d growth and survivorship of larval Neocloeon triangulifer exposed to a gradient of brine salt (mixed NaCl and CaCl2 ) concentrations. Daily growth rates were reduced significantly in all salt concentrations above the control (363 µS cm(-1) ) and larvae in treatments with specific conductance >812 µS cm(-1) were in comparatively earlier developmental stages (instars) at the end of the experiment. Survivorship declined significantly when specific conductance was >1513 µS cm(-1) and the calculated 20-d 50% lethal concentration was 2866 µS cm(-1) . The present study's results provide strong experimental evidence that elevated ion concentrations similar to those observed in developing energy resources, such as oil and gas drilling or coal mining, can adversely affect sensitive aquatic insect species.

Physiological responses to short-term thermal stress in mayfly (Neocloeon triangulifer) larvae in relation to upper thermal limits

“…The mayfly N. triangulifer is emerging as a laboratory model species to study chemical pollutants (Conley et al, 2009;Kim et al, 2012;Xie et al, 2010;Struewing et al, 2014), salinity (Johnson et al, 2015;Soucek and Dickinson, 2015) and temperature (Sweeney and Vannote, 1984). Here we used life cycle rearing experiments to establish thermal reaction norms to provide context for physiological changes in N. triangulifer associated with increasing temperatures.…”

“…This parthenogenetic species (see Funk et al, 2006) has emerged as a useful laboratory model for ecological (Sweeney and Vannote, 1984) and physiological/toxicological studies (Sweeney et al, 1993;Conley et al, 2009Conley et al, , 2011Conley et al, , 2013Conley et al, , 2014Kim et al, 2012;Kunz et al, 2013;Soucek and Dickinson, 2015;Xie et al, 2010;Xie and Buchwalter, 2011;Johnson et al, 2015). We established chronic upper thermal limits by rearing newly hatched eggs to adulthood across several temperatures.…”

Salinized rivers: degraded systems or new habitats for salt-tolerant faunas?

“…However, relationships between sublethal effects and salinity are often non-monotonic, with some freshwater species performing optimally at intermediate salinity [37][38][39]. In contrast, an increase in growth or development was not observed with slightly elevated salinity in three ephemeropteran species [2,35]. EPT DCOH i n c r e a s i n g l y r a r e i n n a t u r e Figure 1.…”

“…Anthropogenic increases in riverine salinization usually result in modest salinities (1-10 mS cm 21 range [1,2]) compared with natural saline lakes, but rivers occasionally increase to the levels of highly saline lakes (. 100 mS cm 21 [3]).…”

Incorporating evolutionary insights to improve ecotoxicology for freshwater species

“…In addition to lethal effects, exposure of freshwater animals to elevated chloride concentrations in the 100s or 1,000s of mg/L can induce of a suite of sublethal effects. These effects include osmoregulatory disruption (Karraker & Gibbs, 2011a), diminished growth and development (Johnson et al., 2015), increased malformations and disease susceptibility (Brady, 2013; Hopkins, French, & Brodie, 2013; Karraker & Ruthig, 2009), and behavioral changes (Hall et al., 2017), all of which can influence fitness, community dynamics, and ecosystem function (Schuler et al., 2017; Van Meter & Swan, 2014). …”