Interactive Impacts of Silver and Phosphorus on Autotrophic Biofilm Elemental and Biochemical Quality for a Macroinvertebrate Consumer

Abstract

Autotrophic biofilms are complex and fundamental biological compartments of many aquatic ecosystems. In particular, these biofilms represent a major resource for many invertebrate consumers and the first ecological barrier against toxic metals. To date, very few studies have investigated the indirect effects of stressors on upper trophic levels through alterations of the quality of biofilms for their consumers. In a laboratory study, we investigated the single and combined effects of phosphorus (P) availability and silver, a re-emerging contaminant, on the elemental [carbon (C):nitrogen (N):P ratios] and biochemical (fatty acid profiles) compositions of a diatom-dominated biofilm initially collected in a shallow lake. We hypothesized that (1) P and silver, through the replacement of diatoms by more tolerant primary producer species, reduce the biochemical quality of biofilms for their consumers while (2) P enhances biofilm elemental quality and (3) silver contamination of biofilm has negative effects on consumers life history traits. The quality of biofilms for consumers was assessed for a common crustacean species, Gammarus fossarum , by measuring organisms’ survival and growth rates during a 42-days feeding experiment. Results mainly showed that species replacement induced by both stressors affected biofilm fatty acid compositions, and that P immobilization permitted to achieve low C:P biofilms, whatever the level of silver contamination. Gammarids growth and survival rates were not significantly impacted by the ingestion of silver-contaminated resource. On the contrary, we found a significant positive relationship between the biofilm P-content and gammarids growth. This study underlines the large indirect consequences stressors could play on the quality of microbial biomass for consumers, and, in turn, on the whole food web.

Herbicide-Induced Shifts in the Periphyton Community Composition Indirectly Affect Feeding Activity and Physiology of the Gastropod Grazer Physella acuta

“…Especially diatoms are rich in HUFAs (e.g., 20:5n-3), while chlorophytes and cyanobacteria are generally poor in these FAs . Therefore, shifts in the periphyton community composition induced by external factors (e.g., nutrients and chemical stressors) can alter the abundance of essential macronutrients, such as HUFAs, and thus change the food quality for grazers and consequently their activity (e.g., feeding activity) and physiology. , …”

The toxicity of coated silver nanoparticles to the alga Raphidocelis subcapitata

“…Primary producers in the aquatic system are vulnerable and are targeted first by contaminants. Any adverse effects to the autotrophs will have an effect on the heterotrophs [18,49]. Several studies have proven that AgNPs are toxic to algae [25,44].…”

The significance of biofilms to human, animal, plant and ecosystem health

“…Omega‐3 are essential for many species, including humans, to ensure a correct metabolism and a competent immune system (Boëchat et al., 2011; Guo et al., 2015; Hixson et al., 2015). Due to stressors, biofilm composition often shifts from diatom dominated towards cyanobacteria dominated, with a decrease in omega‐3 content (Crenier et al., 2019; Hixson et al., 2015; Leflaive et al., 2015). The implications of such a reduced nutritional value have rarely been explored in practice for consumer health and infectious disease susceptibility.…”

“…However, Crenier et al. (2019) showed that a composition shift could impact the growth and survival of a crustacean species. Similarly, the fact that biofilms can adsorb pollutants can be deleterious for biofilm consumers, depending on the fate of pollutants therein (Bonnineau et al., 2020).…”