Photosynthetic performance of symbiont-bearing foraminifera Heterostegina depressa affected by sunscreens

Abstract

Foraminifera are abundant unicellular organisms that play an important role in marine element cycles. A large benthic foraminifer obligatory bearing photosymbionts is Heterostegina depressa. We studied potential impacts of sunscreens available on the market on the activity of photosymbionts on H. depressa by means of pulse-amplitude modulated (PAM) fluorescence microscopy. We included four different sunscreens, with two of them sold as “conventional” and two more stated as “eco-friendly”. Further, the impact of pure Ensulizole (phenylbenzimidazole sulfonic acid) was tested, which is a common agent of sunscreens. Foraminifera were incubated at varying concentrations (10, 50 and 200 mgL−1) of different sunscreens and the pure Ensulizole for 14 days. The photosynthetic performance was measured after 1,3, 7 and 14 days. Pure Ensulizole had a strong negative impact on the photobionts, which was reflected by a significant reduction of the areal fluorescence signal. “Eco-friendly” sunscreens affected the health of foraminifera more severely compared to “conventional” ones. We assume that metal nanoparticles like titanium dioxide or zinc oxide of “eco-friendly” sunscreens are causing this impact, because these substances were already classified as toxic for several microorganisms.

The change in metabolic activity of a large benthic foraminifera as a function of light supply

“…Generally, the assemblages of living LBFs are highly dependent on physical parameters like habitat depth, light supply and water motion 7 . Observing LBFs activity is suitable to detect chemical contaminants in seawater 8 . Thus, regular monitoring of LBFs can be used as an important tool to characterize the health state of coral reefs.…”

Impact of heavy metals (Cu, Fe, Pb, Zn) on carbon and nitrogen uptake of the diatom-bearing benthic foraminifera Heterostegina depressa

“…Other studies have shown that Zn is released into the environment as ZnO nanoparticles, which are harmful to a variety of organisms [ 33 , 47 ]. Lintner et al [ 34 ] tested the influence of sunscreens containing such nanoparticles on H. depressa and they noticed ZnO as a potential ingredient reduced the photosynthetic area of the symbionts.…”

“…The availability of iron is associated with the regulation of algal communities in coastal upwelling regimes and assists in the development of diatom blooms [ 32 ]. Zinc (oxide) nanoparticles deriving from sunscreens released by human into the environment at global beaches are presumably considered harmful to a variety of marine microorganisms [ 33 , 34 ]. Highly increased (1044 x Zn enrichment) concentrations of Zn negatively affected the metabolism of foraminifera [ 35 ].…”

Effect of micro-plastic particles on coral reef foraminifera

“…We applied non-invasive PAM fluorescence imaging to assess possible effects of microplastic particles on foraminifera and particularly on the functionality of their photosymbionts. This PAM approach has been used in previous studies to measure effects of pollutants and environmental parameters like heavy metals, toxic substances, temperature and total alkalinity on foraminiferal symbiont activity [33][34][35] www.nature.com/scientificreports/ perspective, PAM imaging primarily indicates the condition of the photoactive symbionts, and thus provides indirect information on the host performance but important insight into holobiont systems biology. If addressing the whole organism (holobiont), complementary approaches are recommended.…”