Abstract
Changes in the biochemical composition of primary producers can alter their food quality, influencing their consumers and further propagating through the food web. Gamma (ɣ) radiation is an environmentally important type of ionising radiation as it can damage macromolecules such as DNA, proteins, and lipids due to its high frequency, short wave length, and high energy photons. Here, we investigate whether short-term ɣ-radiation changes the biochemical composition of primary producers and if radiation-induced changes affect higher trophic levels. Two phytoplankton species were exposed to two doses of ɣ-radiation and compared to a control. The metabolic profile and total protein content of the algae were measured at five time points within 24 hours. Additionally, we measured carbon incorporation rates of Daphnia magna fed with the exposed algae. Gamma radiation had a significant effect on phytoplankton biochemical composition, although these effects were species-specific. The changes in phytoplankton biochemical composition indicate that ɣ-radiation induced the production of reactive oxygen species (ROS). D. magna incorporated more carbon when fed with algae previously exposed to ɣ-radiation; this could be due to radiation-induced changes in nutritional quality, algal anti-grazing defences, or chemical feeding stimuli.
Highlights
The biochemical composition, or food quality, of primary producers can affect the productivity of aquatic food webs (Sterner and Hessen, 1994; Vrede et al, 2004; Malzahn et al, 2010)
We investigated the effects of external, short-term È-radiation on the biochemical composition of two phytoplankton species and whether radiation-induced effects on primary producers affected their suitability as food for primary consumers
Our results indicate that È-radiation had a significant effect on the biochemical composition and primary production of phytoplankton, but these effects were species specific
Summary
The biochemical composition, or food quality, of primary producers can affect the productivity of aquatic food webs (Sterner and Hessen, 1994; Vrede et al, 2004; Malzahn et al, 2010). One of the challenges in aquatic ecology is to predict how changes in primary production propagate up the food chain. As primary producers synthesize many biochemical compounds, such as essential fatty and amino acids that cannot be synthesized by primary consumers like crustaceous zooplankton, the food quality of primary producers has been shown to be important for reproduction and growth in copepods and cladocerans (Elser and Hassett, 1994). Exposure to contaminants has been shown to change the biochemical composition of microalgae. In the presence of pesticides, the fatty acid (FA) profile of various microalgae changed
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