Rhamnolipids Mediate the Effects of a Gastropod Grazer in Regards to Carbon–Nitrogen Stoichiometry of Intertidal Microbial Biofilms

Stephanie Gill, Louise Kregting, Ibrahim M Banat, Joerg Arnscheidt, William R Hunter

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Microbial biofilms have co-evolved with grazing animals, such as gastropods, to develop mutually beneficial relationships. Although microbial biofilms demonstrate resilience and resistance to chemical exposure, pre-existing relationships can be negatively affected by chemical input. In this study, we determined how the grazer, Littorina littorea (common periwinkle sea snail), and a biological surfactant (rhamnolipid) interact on a phototrophic marine biofilm. Biofilms were cultured in 32 twenty-liter buckets at the Queen’s University Marine Laboratory in Portaferry, Northern Ireland on clay tiles that were either exposed to 150 ppm of a rhamnolipid solution or that had no chemical exposure. L. littorea were added into half of the buckets, and biofilms were developed over 14 days. Biofilms exposed to grazing alone demonstrated high tolerance to the disturbance, while those growing on rhamnolipid-exposed substrate demonstrated resistance but experienced slight declines in carbon and stoichiometric ratios. However, when exposed to both, biofilms had significant decreases in stoichiometry and declined in productivity and respiration. This is problematic, as continuing marine pollution increases the likelihood that biofilms will be exposed to combinations of stressors and disturbances. Loss of biofilm productivity within these areas could lead to the loss of an important food source and nutrient cycler within the marine ecosystem.
Original languageEnglish
Article number12729
Pages (from-to)1-10
Number of pages10
JournalApplied Sciences
Issue number24
Early online date12 Dec 2022
Publication statusPublished online - 12 Dec 2022

Bibliographical note

Funding Information:
SG is funded by an Ulster University Vice Chancellors Doctoral Research Fellowship and received additional support through the G and M Williams Fund. Analytical costs were partly supported by core funding from the AFBI Aquatic Chemistry Laboratory (BH).

Publisher Copyright:
© 2022 by the authors.


  • aquatic toxicology
  • biofilm
  • marine snails
  • metabolic activity
  • surfactants


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