The dynamics of biogeographic ranges in the deep sea

Abstract

Anthropogenic disturbances such as fishing, mining, oil drilling, bioprospecting, warming, and acidification in the deep sea are increasing, yet generalities about deep-sea biogeography remain elusive. Owing to the lack of perceived environmental variability and geographical barriers, ranges of deep-sea species were traditionally assumed to be exceedingly large. In contrast, seamount and chemosynthetic habitats with reported high endemicity challenge the broad applicability of a single biogeographic paradigm for the deep sea. New research benefiting from higher resolution sampling, molecular methods and public databases can now more rigorously examine dispersal distances and species ranges on the vast ocean floor. Here, we explore the major outstanding questions in deep-sea biogeography. Based on current evidence, many taxa appear broadly distributed across the deep sea, a pattern replicated in both the abyssal plains and specialized environments such as hydrothermal vents. Cold waters may slow larval metabolism and development augmenting the great intrinsic ability for dispersal among many deep-sea species. Currents, environmental shifts, and topography can prove to be dispersal barriers but are often semipermeable. Evidence of historical events such as points of faunal origin and climatic fluctuations are also evident in contemporary biogeographic ranges. Continued synthetic analysis, database construction, theoretical advancement and field sampling will be required to further refine hypotheses regarding deep-sea biogeography.

Molecular taxonomy and naming of five cryptic species ofAlviniconchasnails (Gastropoda: Abyssochrysoidea) from hydrothermal vents

“…Deep-sea organisms are woefully undersampled because of the great depths, unpredictable oceanographic conditions and great expense associated with exploring the vast abyssal areas that cover nearly 70% of Earth's surface (McClain & Hardy, 2010). Consequently, our understandings of deep-sea biodiversity and biogeography are relatively poor, even for faunas that have received considerable attention, such as those inhabiting hydrothermal vents and other chemosynthesis-based environments (e.g.…”

Diversity, distribution and spatial structure of the cold-water coral fauna of the Azores (NE Atlantic)

“…However, the same relationship was not observed in another brooding species, Anthomastus grandiflorus (Mercier and Hamel, 2011), which has a wide geographical distribution. It seems therefore clear that although larval type may largely determine dispersal potential, a number of other factors such as dispersal barriers, currents and larval behaviour may come into play to modulate realized dispersal and limit range size (McClain and Hardy, 2010). Finally, a hypothetical role of asexual reproduction (budding, fission, parthenogenesis, etc.…”

Analysis of the community structure of abyssal kinetoplastids revealed similar communities at larger spatial scales

“…Moreover, as many genetically studied microbial eukaryotes from the deep sea have revealed wide distribution ranges (Pawlowski et al, 2007;Lecroq et al, 2009). In their extensive review on deep-sea biogeography, these authors furthermore noticed that many taxa appear widely distributed across the deep sea, even at specialized environments such as hydrothermal vents (McClain and Hardy, 2010). The fact that we had no linear relationship among the number of identical clones (0.00% p-distance) between two sampling regions in relation to the total number of clones at both sampling regions and the geographical distance between both regions (r ¼ À0.05, P40.05), may point into that direction.…”

“…Furthermore, as the kinetoplastid-specific clone libraries from the South-East Atlantic, reported here, show the same pattern as clone libraries built with general eukaryotic primers as reported by Scheckenbach et al (2010), it is admissible to assume that the pattern reported here for both the South-East and South-West Atlantic may be similar for other groups of microbial eukaryotes. The assumption of McClain and Hardy (2010), that geographical ranges may increase with depth as environmental conditions become more constant and homogeneous, may therefore be plausible. Moreover, as many genetically studied microbial eukaryotes from the deep sea have revealed wide distribution ranges (Pawlowski et al, 2007;Lecroq et al, 2009).…”