Marine Biodiversity

by

Paul Snelgrove, Roberto Danovaro

• LAST MODIFIED: 25 July 2023
• DOI: 10.1093/obo/9780199830060-0245

Introduction

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.

General Overviews

Because marine biodiversity encompasses the immense wide range of life forms in the ocean and influences a wide range of ecosystem processes, marine biodiversity science strongly integrates with fisheries science, conservation science, and other environmental sub-disciplines. Indeed, marine biodiversity science has progressed from a largely curiosity-driven discipline to one embraced by conservation practitioners and by fisheries management within the context of ecosystem-based management and ecosystem-based fisheries management. This uptake links to increasing recognition of the role of biodiversity in ecosystem processes ranging from food web support to habitat provisioning and beyond, to direct benefits to humans such as fisheries. Human interest in marine life dates to the earliest prehistoric cave drawings, such as those in Cosquer Cave near Marseilles, France dating back to 18,500–33,000 years ago, and mosaics and writings of Greek scholars such as Aristotle, as revealed by the relatively new discipline of historical ecology, described in Starkey, et al. 2012. From the spectacular visual complexity of coral reefs to the (apparently) much more homogenous deep sea, research interest in marine biodiversity and its drivers progressed irregularly until the second industrial revolution (also known as the technological revolution of the late 19th century), accelerating over the last fifty or more years. Although marine biodiversity appeared historically in a wide range of related disciplines such as fisheries and basic ecology, specific focus on marine biodiversity as a discipline has sharpened in the last twenty to thirty years, aided by the acceleration of data aggregation efforts such as the Ocean Biodiversity Information System. Around the time the seminal book Wilson 1988 was published, marine biodiversity scientists were identifying major knowledge gaps on marine biodiversity and threats arising from human activities. The National Research Council 1995 subsequently published a “research needs” summary from a US experts group that would help to catalyze syntheses of knowledge on marine biodiversity by works such as Ormond, et al. 1997, as well as the decade-long international Census of Marine Life program that focused on marine biodiversity, summarized in McIntyre 2010 and Snelgrove 2010. Norse and Crowder 2005 catalyzed the application of marine biodiversity knowledge to conservation needs, and Danovaro, et al. 2008 provides the first evidence linking biodiversity and ecosystem processes. In parallel, researchers such as those in Solan, et al. 2012 worked to develop methodologies to study biodiversity and ecosystem function in tandem, whereas Worm and Tittensor 2018 serves as a theoretical basis for understanding global marine (and terrestrial) biodiversity patterns.

• Danovaro, R., C. Gambi, A. Dell’Anno, et al. 2008. Exponential decline of deep-sea ecosystem functioning linked to benthic biodiversity loss. Current Biology 18.1: 1–8.

  DOI: 10.1016/j.cub.2007.11.056

  This paper was among the first to link biodiversity and ecosystem functioning in marine environments and helped to set the stage for many subsequent studies that examined such relationships.

• McIntyre, A., ed. 2010. Life in the world’s oceans: Diversity, distribution, and abundance. West Sussex, UK: Wiley-Blackwell.

  This volume of contributed chapters summarizes each of the seventeen major projects completed during the decade-long Census of Marine Life and thus provides a relatively recent update on state of knowledge on diversity, distribution, and abundance of life in different marine ecosystems and major groups of organisms.

• National Research Council. 1995. Understanding marine biodiversity. Washington, DC, National Academies Press.

  The United States National Academy of Sciences convened an expert group of marine scientists to identify threats and needs regarding marine biodiversity; they identified the need for a major program to understand biodiversity and its threats, and thus helped to catalyze support for the Census of Marine Life program.

• Norse, E. A., and L. B. Crowder. 2005. Marine conservation biology: The science of maintaining the sea’s biodiversity. Washington, DC: Island Press.

  Norse and Crowder really helped to launch the field of marine conservation with this book, which identified major gaps and needs in ocean conservation science.

• Ormond, R. F., J. D. Gage, and M. V. Angel, eds. 1997. Marine biodiversity: Patterns and processes. New York: Cambridge Univ. Press.

  This edited volume presents diverse perspectives on emerging analyses regarding patterns in marine biodiversity in multiple marine ecosystems and the processes that drive those patterns.

• Snelgrove. P. V. R. 2010. The census of marine life: Making ocean life count. Cambridge, UK: Cambridge Univ. Press.

  A single-author synthesis of the outcomes of the international Census of Marine Life program and its goals of assessing the diversity, distribution, and abundance of ocean life.

• Solan, M., R. J. Aspden, and D. M. Paterson, eds. 2012. Marine biodiversity and ecosystem functioning: Frameworks, methodologies, and integration. Oxford: Oxford Univ. Press.

  A book of contributed chapters that provides the first synthesis of approaches to examining biodiversity and ecosystem functioning relationships in marine environments.

• Starkey, D. J., P. Holm, and M. Barnard, eds. 2012. Oceans past: Management insights from the history of marine animal populations. Abington, UK: Routledge.

  An early effort to establish environmental history as a disciplinary approach to understanding ocean change, with potential management applications.

• Wilson, E. O. 1988. Biodiversity. Washington, DC: National Academies Press.

  A classic treatise on the diversity of life and its importance; this book played a significant role in moving biodiversity not only into the science mainstream but also into public consciousness.

• Worm, B., and D. P. Tittensor. 2018. A theory of global biodiversity. Princeton, NJ: Princeton Univ. Press.

  DOI: 10.2307/j.ctt1zkjz6q

  Draws together information on patterns of biodiversity in diverse ecosystems to develop an integrative and unifying theory on temperature and community size to explain these patterns.