Losing pieces of the puzzle: threats to marine, estuarine, and diadromous species

The number of marine species at risk of extinction is rising. Understanding the threats that contribute to extinction risk in the seas is thus critical to conservation. When major threats to marine, estuarine, and diadromous species on the US Endangered Species Act and IUCN Red lists were ranked according to the number of species they affect, strong consensus in the ranking of threats across species and between institutions emerged. Overexploitation is the most frequent threat to vulnerable marine species, with approximately half of threatened species caught as bycatch in fisheries. Habitat degradation, the primary threat to terrestrial species, ranks second in impact on marine species. Loss of listed marine species would probably affect ecosystem function and delivery of ecosystem services because many of these species are strong inter-actors, including ecosystem engineers, taxa that provide important nutrient links between terrestrial and marine ecosystems, and a disproportionate number of high trophic-level predators.