Combined effects of interspecies interaction, temperature, and zinc on Daphnia longispina population dynamics

Abstract

Under natural conditions, organisms can experience a variety of abiotic (e.g., temperature, pH) and biotic (e.g., species interactions) factors, which can interact with toxicant effects. By ignoring species interactions conventional ecotoxicological studies (i.e., single-species tests) oversimplify the actual field situation. We investigated whether temperature and interspecific competition affected the effects of zinc (Zn) on a Daphnia longispina population. The D. longispina populations were exposed in a full factorial design to 3 different Zn treatments (background, 29, and 110 μg Zn/L), 2 different temperature regimes (cold, 17-18 °C; warm, 21-22 °C), and 2 interspecific competition levels (no interspecific Brachionus competition = no Brachionus calyciflorus added; interspecific Brachionus competition = B. calyciflorus added). Interspecific Brachionus competition and temperature by itself had a limited effect on the Daphnia abundance but significantly interacted with the highest Zn concentration. Without Brachionus competition the D. longispina juvenile and adult abundances under warm conditions were up to 5.5 and 21 times lower, respectively, in the high Zn treatment in comparison with the Zn control, whereas under cold conditions no significant Zn effect was observed. However, with Brachionus competition the highest Zn treatment was on average 2.2 times less toxic to the D. longispina juvenile abundance at higher temperatures. Under cold conditions the highest Zn treatment affected the juvenile abundance sooner and up to 9 times more negatively when simultaneously faced with Brachionus competition. It is possible that the competition for food reduced the amount of energy that could be used by D. longispina for reproduction, and the metabolic costs increased as a result of Zn stress. The present study clearly illustrated the influence of temperature and competition on the effects of a chemical stressor. Thus, not considering such factors in ecological risk assessment may underestimate or overestimate risks in aquatic ecosystems when extrapolating data from standard single-species tests to the field. Environ Toxicol Chem 2018;37:1668-1678. © 2018 SETAC.

Daphnia magna filtration, swimming and mortality under ammonium, nitrite, nitrate and phosphate

“…However, Daphnia might be sensitive to some compounds. For this reason they are sometimes used to test water quality (Heger et al, 2018;Van de Perre et al, 2018) because many compounds are toxic for these organisms (Sladkova et al, 2016). Nitrate (NO3 -) concentrations above 56 mgN-NO3 -L -1 (250 mgNO3 -L -1 ) together with a water temperature of 26 °C proved to have lethal effects on a Daphnia population (Maceda-Veiga et al, 2015).…”

Ecotoxicity of Lead to a Phytoplankton Community: Effects of pH and Phosphorus Addition and Implications for Risk Assessment

“…Fourth, although somewhat more speculative, species interactions (absent in single‐species studies) may have affected the toxicity‐modifying effect of pH on Pb toxicity. Van De Perre et al 2018, for instance, demonstrated that the addition of a rotifer ( Brachionus ) to a test system affected the toxicity‐modifying effect of temperature on Zn toxicity to a Daphnia population. However, we are unaware of similar types of studies with phytoplankton communities.…”

Integrating Bioavailability of Metals in Fish Population Models

“…To investigate the effect of metals at the population level, one can perform population‐level experiments such as mesocosms or microcosms (Van de Perre et al 2018; Pereira et al 2019). However, this is not always feasible due to ethical and practical constraints, especially for vertebrate organisms such as fish.…”