Marine Biodiversity

The term marine biodiversity encompasses a broad range of subjects, spanning from descriptions of single species, or taxa, to habitats and ecosystems, and indeed the global ocean. The Convention on Biological Diversity defines biodiversity (or biological diversity) as “the variability among living organisms from all sources, including inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems,” A comprehensive summary of marine biodiversity must therefore consider biodiversity at genetic, systematic (phylogenetic), taxonomic (species or higher), functional (specific functional role), and biogeographic (habitat, ecosystem, or regional) levels. Pragmatically, management efforts typically focus on species-level diversity, and often on species richness, which will form a primary focus here. Marine biodiversity science investigates a variety of topics, from describing the spatial and temporal patterns of biodiversity, to experimental and observational approaches to understanding drivers of biodiversity patterns, and the linkages between biodiversity and ecosystem functioning. Marine biodiversity also provides a crucial contribution to ocean goods and services, so that potential biodiversity loss represents one of the major threats for the functioning of our planet. The increasing human pressures on ocean resources, in tandem with human activities (e.g., fossil fuel release, agriculture, pollution) are causing significant change in oceans and marine life. These changes create a pressing need for marine biodiversity conservation efforts. The major gaps in our understanding of drivers, patterns, and ecological consequences of marine biodiversity underscore a need for better ocean sampling and an increased ability to recognize and describe species at least to the OTU (operational taxonomic unit, often used by microbiologists because of the difficulty in applying the concept of species) level. These efforts require integrated taxonomic approaches to overcome challenges such as identifying sibling species (species with identical phenotype but different genotype). It also punctuates a need to review current taxonomy, recognize functional traits, understand their complex life cycles, and comprehend species’ ecology and their roles within marine ecosystems. The article begins by reviewing how marine biodiversity fundamentally differs from terrestrial biodiversity, and describing biodiversity in marine habitats and its variation. It then recaps the evolutionary history of marine biodiversity and its broad biogeographic patterns, as well as proposed drivers. It then summarizes the current threats to marine biodiversity and describes the emerging tools available to help in conservation efforts. Finally, it summarizes some of the dominant gaps and opportunities for marine biodiversity research.