The bacterial community composition of American Lobster (Homarus americanus) embryos and recently hatched larvae held under experimental laboratory conditions

Previous research investigating the microbial community of American lobster embryos has long led researchers to believe this habitat comprised only a select few bacterial taxa. However, using 16 S rRNA gene sequencing, we show this community to be more diverse than previously thought. We have characterized the microbiome on lobster embryos held in a long-term laboratory experiment, investigated how the bacterial communities of American lobster embryos and larvae changed over embryogenesis and hatching in response to two environmental variables, and identified core members of the microbiome on embryos and larvae at two different developmental stages. Ovigerous female lobsters caught from Maine and Massachusetts were held under varying temperature and pH regimes that approximated observed and predicted warming and ocean acidification conditions in the Gulf of Maine (GoM) and Southern New England (SNE). The bacterial microbiome associated with the lobster embryos was quantified from two-time points during the 5-month experiment, as well as larvae collected within 12 h of hatching. Alpha diversity increased with each life history stage, and embryo and larvae microbiomes shared little community overlap with that in the surrounding tank water. Neither environmental conditions nor lobster origin significantly altered bacterial communities, with life history stage driving alpha and beta diversity. Embryos and larvae shared three core bacterial members identified as members of the genera Rubritalea, Delftia, and Stenotrophomonas. American lobster embryos and larvae appear to have a highly selective microhabitat for bacteria that showed little alteration by environmental conditions in laboratory aquaria. Additional studies are warranted on the role of the microbiome in the health of the developing lobster embryo and where the microbiome originates, if not from the surrounding seawater.