If an R package is used for work that is published, the developers and maintainers of the package should be appropriatly cited.
citation gives the necessary information for the citation.
citation('oce')
#
# To cite package ‘oce’ in publications use:
#
# Dan Kelley and Clark Richards (2016). oce: Analysis of Oceanographic
# Data. R package version 0.9-20.
# https://CRAN.R-project.org/package=oce
#
# A BibTeX entry for LaTeX users is
#
# @Manual{,
# title = {oce: Analysis of Oceanographic Data},
# author = {Dan Kelley and Clark Richards},
# year = {2016},
# note = {R package version 0.9-20},
# url = {https://CRAN.R-project.org/package=oce},
# }