Delayed effects and complex life cycles: How the larval aquatic environment influences terrestrial performance and survival

Abstract

Species with complex life cycles are susceptible to environmental stressors across life stages, but the carryover and latent effects between stages remain understudied. For species with biphasic life histories, such as pond-breeding amphibians, delayed effects of aquatic conditions can influence terrestrial juveniles and adults directly or indirectly, usually mediated through fitness correlates such as body size. We collected adult southern toads (Anaxyrus terrestris) from 2 source populations-a natural reference wetland and a metal-contaminated industrial wetland-and exposed their offspring to 2 aquatic stressors (a metal contaminant, copper [Cu], and a dragonfly predator cue) in outdoor mesocosms (n = 24). We then reared metamorphs in terraria for 5 mo to examine delayed effects of early life stage environmental conditions on juvenile performance, growth, and survival. Larval exposure to Cu, as well as having parents from a contaminated wetland, resulted in smaller size at metamorphosis-a response later negated by compensatory growth. Although Cu exposure and parental source did not affect larval survival, we observed latent effects of these stressors on juvenile survival, with elevated Cu conditions and metal-contaminated parents reducing postmetamorphic survival. Parental source and larval Cu exposure affected performance at metamorphosis through carryover effects on body size but, 1 mo later, latent effects of parental source and larval predator exposure directly (i.e., not via body size) influenced performance. The carryover and latent effects of parental source population and aquatic Cu level on postmetamorphic survival and juvenile performance highlight the importance of conducting studies across life stages and generations. Environ Toxicol Chem 2018;37:2660-2669. © 2018 SETAC.

Carryover effects from environmental change in early life: An overlooked driver of the amphibian extinction crisis?

“…The capacity for environmental stressors encountered by embryonic and larval amphibians to affect physiology post‐metamorphosis is well‐established (Denver & Middlemis‐Maher, 2010; Rumrill et al, 2018). However, research on UVR‐induced carryover effects is lacking.…”

Sensitivity of Amphibians to Copper

“…However, Cu can interfere with amphibian development and metamorphosis in several ways, including: (1) reducing the proportion of individuals of a population that complete metamorphosis (Chen et al 2007;Chai et al 2014;Chai et al 2017); (2) delaying the Accepted Article onset and/or duration of metamorphosis (i.e., lengthening the larval period; García-; Parris and Baud, 2004;Chen et al, 2007;García-Muñoz et al, 2009;Peles, 2013;Wang et al, 2016;Calfee and Little, 2017); and (3) altering the whole-body size (length and weight) and/or length of body parts (e.g., tail and front-and hind-limbs) at specific stages in metamorphosis (e.g., GS 42 and 46; Chai et al, 2017). Timing of and size at metamorphosis can be indicative of individual survival and behavior post-metamorphosis and population-level effects (James and Semlitsch 2011;Willson et al 2012;Searcy et al 2015;Rumrill et al 2018). The effects of Cu exposure on metamorphosis are seen across several species, demonstrating that Cu disrupts thyroid hormone metabolic and/or signaling pathway (Thambirajah et al 2019).…”

Concomitant exposure to benzo[a]pyrene and triclosan at environmentally relevant concentrations induces metabolic syndrome with multigenerational consequences in Silurana (Xenopus) tropicalis

“…Delayed metamorphosis could affect progeny survival in cases of early desiccation of temporary ponds (Rumrill et al, 2018). Along with lower body weight at metamorphosis, it could also reduce adult recruitment and the chances of successful reproduction (Smith, 1987, Todd et al, 2011.…”