The effects of temperature on Bosmina longirostris susceptibility to microcystin-LR acute toxicity

Abstract

Harmful algal blooms are an ongoing threat to many aquatic systems throughout the world. In the Chowan River, North Carolina, the frequency of toxin producing Microcystis aeruginosa blooms has increased since 1975 along with an average 0.71°C rise in water temperature. The combined effect of microcystin-LR toxin and rising temperatures on a dominant zooplankter in the system, Bosmina longirostris , was the focus of this study. Laboratory studies were conducted to determine how microcystin-LR, produced from M . aeruginosa blooms, affected B . longirostris mortality under different temperature regimes. At 25°C, the LC 50 for B . longirostris was 26.3 μg L -1 suggesting that B . longirostris can survive typical current bloom microcystin-LR concentrations ranging 0.1μg L -1 to 2.0 μg L -1 , but would be susceptible to higher concentrations they may be periodically exposed to. Mortality was assessed at a constant microcystin-LR concentration of 26.3 μg L -1 over 15–35°C, and it was found that B . longirostris mortality increased at higher temperatures. B . longirostris mortality increased approximately 18% due to microcystin-LR alone over 2°C between 25°C and 27°C when exposed to the LC 50 concentration. The increased prevalence of toxic M . aeruginosa blooms and increasing temperatures due to climate change may reduce B . longirostris populations, potentially affecting larval fish and fisheries in the Chowan River, North Carolina.

Combined effects of increased water temperature and cyanobacterial compounds exert heterogeneous effects on survival and ecological processes in key freshwater species

“…Such temperature-mediated toxicity could be responsible for the 50% decline observed in the survival of I. elegans exposed to high concentration of the crude extract at 25 °C in our study. Here, our finding supports the hypothesis on the combined effects of temperature and crude extract and corroborates earlier studies that demonstrated their combined effects on freshwater species (Kim et al 2014 ; Lamb et al 2019 ; Xiang et al 2017 ). Hence, the present study suggests that warming may co-occur with a much broad range of cyanobacterial metabolites following bloom senescence leading to impaired survival and feeding among important species (Paerl and Huisman 2008 ; Walls et al 2018 ).…”

Combined effects of a simulated marine heatwave and an algal toxin on a tropical marine aquaculture fish cobia ( Rachycentron canadum )

“…In general, the toxicity of a range of substances such as metals (Dinh et al, 2013;Janssens, Dinh, Debecker, Bervoets, & Stoks, 2014;Sokolova & Lannig, 2008) and pesticides (Dinh, Janssens, Debecker, & Stoks, 2014a;Dinh, Janssens, & Stoks, 2016;Holmstrup et al, 2010) increases under elevated temperatures, causing synergistic effects of the stressors (Crain, Kroeker, & Halpern, 2008;Dinh et al, 2013Dinh et al, , 2014aDinh et al, , 2016Sokolova & Lannig, 2008). However, it is relatively unknown how the harmful effects of algal toxins may change under extreme temperatures (Lamb, Kimmel, & Field, 2019). This is highly relevant for two reasons.…”

“…Firstly, the co-occurrence of warmer waters and HABs suggests that species may have to cope with both elevated temperatures and algal toxins simultaneously (Dam, 2013;Lamb et al, 2019).…”