marine biome marginal sea biome The marginal sea biome comprises parts of an ocean partially enclosed by land such as islands, archipelagos, or peninsulas. Unlike mediterranean seas, marginal seas have ocean currents caused by ocean winds. Many marginal seas are enclosed by island arcs that were formed from the subduction of one oceanic plate beneath another. ORCID:0000-0002-4366-3088 2010-03-15T11:23:23Z