The effect of temperature on the sensitivity of Daphnia magna to cyanobacteria is genus dependent

etc cover thumb100 Recently a harmful algae bloom made Lake Erie's water temporarily undrinkable in Toledo and surrounding towns in northwest Ohio. Over the last 50 years harmful algal blooms have been a regular occurrence in Lake Erie, with peak concentrations in late summer months. Such harmful algal blooms are commonly produced by cyanobacteria and not only impact water quality but they also have the potential to produce toxins that can harm humans, pets and wildlife. The blooms are caused by a combination of factors that promote high densities and reproduction of algae, one major factor being warmer temperatures. Therefore climate change has been linked to the global expansion of cyanobacteria through changes in temperature. In this publication, we determined the influence of temperature on the sensitivity of Daphnia magna to six different genera of cyanobacteria.We noted that both the sensitivity of Daphnia magna to cyanobacteria and the order of harmfulness of the cyanobacteria studied are temperature dependent. Overall there appears to be no universal increase or decrease in the harmful effects of cyanobacteria to Daphnia magna with temperature, but rather an intricate combination of mechanisms causing certain cyanobacteria to increase their harmful effect on Daphnia at higher temperatures while others may be more harmful at lower temperatures. The publication of this paper is timely given that president Obama has recently signed the bill on research on toxic algae


Scientific abstract

In the present study, the authors investigated the effects of 6 different genera of cyanobacteria on multiple endpoints of Daphnia magnain a 21-d life table experiment conducted at 3 different temperatures (15°C, 19°C, and 23°C). The specific aims were to testif the effect of temperature on Daphnia’s sensitivity to cyanobacteria differed among different cyanobacteria and if the rank order frommost to least harmful cyanobacteria to Daphniareproduction changed or remained the same across the studied temperature range. Overall,the authors observed a decrease in harmful effects on reproduction with increasing temperature for Microcystis, Nodularia, and Aphanizomenon, and an increase in harmful effects with increasing temperature for Anabaenaand Oscillatoria. No effect of temperaturewas observed on Daphniasensitivity to Cylindrospermopsis. Harmful effects of Microcystisand Nodulariaon reproduction appear tobe mirrored by a decrease in length. On the other hand, harmful effects of Anabaena, Aphanizomenon, and Oscillatoriaon reproductionwere correlated with a decrease in intrinsic rate of natural increase, which was matched by a later onset of reproduction in exposures to Oscillatoria. In addition, the results suggest that the cyanobacteria rank order of harmfulness may change with temperature. Highertemperatures may increase the sensitivity of D. magnato the presence of some cyanobacteria (Anabaenaand Oscillatoria) in their diet,whereas the harmful effects of others (Microcystis, Nodularia, and Aphanizomenon) may be reduced by higher temperatures. 

Full reference (link)

Hochmuth J., De Schamphelaere K.A.C. 2014. The effect of temperature on the sensitivity of Daphnia magna to cyanobacteria is genus dependent. Environmental toxicology & Chemistry. 33(10): 2333-2343.