Deep-Sea Meiofauna—A World on Its Own or Deeply Connected?

he deep sea is Earth’s most typical environment and meiofauna its most common and arguably its most diverse metazoan inhabitants. They are therefore key in understanding temporal and spatial patterns in biodiversity and biogeography and are major contributors to ecological processes and functions. Meiofauna are integral to deep-sea benthic communities, with numerous links to other benthic organisms and the interstitial environment, the habitat from where they experience life around them. Although many meiofaunal patterns and relations have been identified, limited progress has been made in answering questions as to “why” and “how” these patterns and relations exist or are formed and maintained, and in many cases such knowledge does not exist. In this chapter, we review the knowledge we do have and present interpretations and explanations that bring a better understanding of how meiofauna patterns in the deep sea can be explained in terms of processes and ecological interactions. We applied this approach in four distinct fields of study: trophic interactions; biodiversity and ecosystem function; distribution and diversity patterns; and connectivity patterns. All four illustrate the extent to which meiofauna relate to other biological components and the abiotic environment. Moreover, technological advances and the increase in multidisciplinary approaches (inherent to offshore deep-sea research) show that meiofauna studies are becoming better integrated with other fields of deep-sea research. Meiofauna, therefore, offer an exciting scientific and diverse future of discovery with research operating at the frontiers of deep-sea science