I.C.E.S	Acronym for International Council for the Exploration of the Sea. The first formal oceanographic society, founded in 1902 and formed with the intention of studying processes of the North Atlantic and adjacent seas. I.C.E.S. is particularly concerned with the environmental questions and the management of fisheries.
immune system	A function within living organisms not affected or responsive, resistant, as to a disease.
infaunal	Animals living within the sediment, as opposed to epifauna (animals living on or near the ocean bottom).
infra-red	That part of the solar radiation spectrum above the wavelength 780 nm.
infra-red radiation	Radiation lying within the infra-red.
intergovernmental co-operation	Co-operation between two different governments.
interstitial	Living in the pore spaces among sedimentary grains in a soft sediment.
invertebrate	Any animal lacking a backbone, including all species not classified as vertebrates.
ion	An electrically charged atom or group of atoms formed by the loss or gain of one or more electrons.
ionization	The process by which a neutral atom or molecule acquires an electric charge.
irrigation	Supplying (land) with water by means of artificial canals, ditches, etc., to promote the growth of food crops.
irritant	Causing irritation: irritating.
isotope	One or two or more atoms with the same atomic number that contain different numbers of neutrons.