Signals of coastal marine bioinvasions in the geological record

Changes resulting from anthropogenic biological invasions in coastal marine and estuarine waters may be preserved as signals in the fossil record. Three types of signals-species appearances, species reductions or disappearances and morphological changes in fossil remains-are discussed. Biological invasions recognized in the geological record have often been characterized by multiple species moving along a new physical connection between two previously isolated regions; however, the signal from anthropogenic marine invasions (with the possible exception of invasions through major canals) will be more diffuse, owing to the multiplicity of invasion routes and frequent changes in the dominant invasion vectors over geologically short periods of time. Governing authorities could limit the anthropogenic marine invasion signal by adequately regulating the transport and release of marine species from one part of the world to another. Unfortunately, even for what is arguably the most important and easiest to manage of modern marine invasion vectors-organisms carried in ships' ballast water tanks-the world's governments have so far failed to take the most obvious regulatory actions. This article is part of the theme issue 'The biosphere in the Anthropocene'.