Influence of bacteria on shell dissolution in dead gastropod larvae and adult Limacina helicina pteropods under ocean acidification conditions
Ocean acidification (OA) increases aragonite shell dissolution in calcifying marine organisms. It has been proposed that bacteria associated with molluscan shell surfaces in situ could damage the periostracum and reduce its protective function against shell dissolution. However, the influence of bacteria on shell dissolution under OA conditions is unknown. In this study, dissolution in dead shells from gastropod larvae and adult pteropods (Limacina helicina) was examined following a 5-day incubation under a range of aragonite saturation states (Ωarag; values ranging from 0.5 to 1.8) both with and without antibiotics. Gastropod and pteropod specimens were collected from Puget Sound, Washington (48°33′19″N, 122°59′49″W and 47°41′11″N, 122°25′23″W, respectively), preserved, stored, and then treated in August 2015. Environmental scanning electron microscopy (ESEM) was used to determine the severity and extent of dissolution, which was scored as mild, severe, or summed (mild + severe) dissolution. Shell dissolution increased with decreasing Ωarag. In gastropod larvae, there was a significant interaction between the effects of antibiotics and Ωarag on severe dissolution, indicating that microbes could mediate certain types of dissolution among shells under low Ωarag. In L. helicina, there were no significant interactions between the effects of antibiotics and Ωarag on dissolution. These findings suggest that bacteria may differentially influence the response of some groups of shelled planktonic gastropods to OA conditions. This is the first assessment of the microbial–chemical coupling of dissolution in shells of either gastropod larvae or adult L. helicina under OA.
The experimental portion of this study was conducted at the University of Washington’s Friday Harbor Laboratories, Washington, USA during a graduate student summer course on ocean acidification. We would like to thank Andrew Dickson and Laura Newcomb for their advice and insights throughout the course; Jessamyn Johnson and Jan Newton for their advice and for providing the Limacina helicina specimens; Kristy Krull, Nicholas Ulacia, and Molly Roberts for their assistance in boat operations to collect the gastropod larvae specimens; Kathryn Van Alstyne and Victoria Foe for providing the antibiotics; Constance Sullivan and the Ocean Acidification Environmental Laboratory staff for their assistance with carbonate chemistry measurements; the Friday Harbor Laboratories faculty and staff for providing funding, facilities, supplies, and logistic support; and two reviewers for providing constructive comments on the manuscript.
Compliance with ethical standards
Conflict of interest
All authors have agreed to the submitted version of this manuscript. We have no conflicts of interest to disclose.
Gastropod and pteropod specimens were sampled and treated in accordance with the ethical standards of Friday Harbor Laboratories, University of Washington.
- Bednaršek N, Tarling GA, Bakker DCE, Fielding S, Cohen A, Kuzirian A, McCorkle D, Lézé B, Montagna R (2012a) Description and quantification of pteropod shell dissolution: a sensitive bioindicator of ocean acidification. Glob Change Biol. https://doi.org/10.1111/j.1365-2486.2012.02668.x Google Scholar
- Brunton LL, Chabner BA, Knollmann BC (eds) (2011) Goodman and Gilman’s the pharmacological basis of therapeutics, 12th edn. McGraw-Hill, New YorkGoogle Scholar
- Cottingham KL, Lennon JT, Brown BL (2005) Knowing when to draw the line: designing more informative ecological experiments. Front Ecol Environ. https://doi.org/10.1890/1540-9295(2005)003[0145:kwtdtl]2.0.co;2Google Scholar
- Dickson AG (2010) The carbon dioxide system in seawater: equilibrium chemistry and measurements. In: Riebesell U, Fabry VJ, Hansson L, Gattuso JP (eds) Guide to best practices for ocean acidification research and data reporting. Publications Office of the European Union, Luxembourg, pp 17–40Google Scholar
- Dickson AG, Sabine CL, Christian JR (2007) Guide to best practices for ocean CO2 measurements. PICES Special Publication. North Pacific Marine Science Organization, Sidney, BC, Canada, pp 1–191Google Scholar
- Harper EM (2000) Are calcitic layers an effective adaptation against shell dissolution in the Bivalvia. Zoology. https://doi.org/10.1111/j.1469-7998.2000.tb00602.x Google Scholar
- R Development Core Team (2016) R: a language and environment for statistical computing. R Foundation for Statistical Computing, ViennaGoogle Scholar
- Robbins LL, Hansen ME, Kleypas JA, Meylan SC (2010) CO2calc: a user-friendly seawater carbon calculator for Windows, Max OS X, and iOS (iPhone). Open-file Rep (US Geol Surv), pp 1-17Google Scholar