Changes in the Magnitude of the Individual and Combined Effects of Contaminants, Warming, and Predators on Tropical Cladocerans across 11 Generations

Abstract

A massive challenge in ecotoxicology is assessing how the interaction of contaminants, climate change, and biotic stressors shapes the structure and functions of natural populations. Furthermore, it is not known whether contemporary evolutionary responses to multiple stressors across multigenerations may alter the interaction of these stressors. To address these issues, we exposed Moina dubia to lead (Pb, 50 μg/L) under two temperatures (25 and 28 °C) with/without predator cues from climbing perch (Anabas testudineus) for 11 generations (F1–F11). We assessed changes in M. dubia fitness, including development time, adult size, lifespan, fecundity, and neonate production. We found strong negative effects of Pb, elevated temperature, and predator cues on the fitness of M. dubia. Strikingly, Pb-induced reduction in the performance of M. dubia was stronger at 25 °C and in the absence of predator cues. The individual and interactive effects of Pb, temperature, and predator cues on M. dubia were stronger across F1–F9 and generally leveled off in F10–F11. Our results highlight the high vulnerability of M. dubia to multiple stressors, thus weakening top-down control on algal blooms in eutrophic lakes. Our study underscores the importance of integrating evolutionary responses in realistic ecotoxicological risk assessments of contaminants interacting with climatic and biotic stressors.

Direct and delayed synergistic effects of marine heatwaves, metals and food limitation on tropical reef-associated fish larvae

“…One crucial aspect that has often been overlooked in laboratory experiments is food availability, which may be a critically important factor determining the susceptibility of studied species to multiple stressors. Indeed, most multiple-stressor studies have been conducted in the laboratory under food saturation levels (e.g., Dinh et al, 2020b; Krause et al, 2017; Pham et al, 2020). However, stressor effects on life history and physiology may only be present or be magnified under food shortages (e.g., Bignami et al, 2016; Dinh et al, 2016a).…”

“…The interaction of warming and contaminants has emerged as a central research theme in global change biology and ecotoxicology in the last decade (Crain et al, 2008; Dinh et al, 2020a; Dinh et al, 2021; Dinh et al, 2020b; Moe et al, 2013; Orr et al, 2020; Sokolova and Lannig, 2008). However, only a few studies have investigated whether an additional stressor, e.g., food limitation, competition, or predation stress, may further modify the interaction of warming and contaminants (Crain et al, 2008; Dinh et al, 2016a; Knillmann et al, 2013; Pham et al, 2020). For example, food limitation combined with the heatwave makes pesticides lethal to aquatic insects (Dinh et al, 2016a).…”

Agent Orange: Haft-Century Effects On The Vietnamese Wildlife Have Been Ignored

“…Evolution of increased tolerance is likely after 50–60 years of exposure to Agent Orange substances, equivalents to several hundred to thousand generations of short-lived aquatic and soil invertebrates, for excample, cladocerans. 8 Adaptations of Vietnamese invertebrates to long-term exposure to metals have recently been observed. 9 Evolutionary responses of surviving animals to Agent Orange can provide unique insights into physiological, epigenetic and genetic mechanisms underpinning the long-term effects of Agent Orange on the hyperdiverse tropical ecosystems such as sprayed forests, lakes, and rivers.…”

“…How long-lasting chemicals work in concert with climate change to affect Vietnamese wildlife is largely unknown. 8 , 14 …”

“…These Vietnamese wildlife animals already face a high risk of extinction by various anthropogenic activities such as land use, deforestation, and element extractions. Potential evolutionary responses of exposed animals to Agent Orange: mechanisms, costs and ecological consequences: Surviving animals must develop an increased tolerance to Agent Orange substances. Evolution of increased tolerance is likely after 50–60 years of exposure to Agent Orange substances, equivalents to several hundred to thousand generations of short-lived aquatic and soil invertebrates, for excample, cladocerans . Adaptations of Vietnamese invertebrates to long-term exposure to metals have recently been observed .…”