Philippe Bouchet | PubMed Health

PubMed2006

Mystery tubes coiled around deep-water tropical gorgonians: fecampiid cocoons (Platyhelminthes: Fecampiida) resembling Solenogastres (Mollusca).

During the examination of a large suite of tropical deep-water molluscs, a number of Solenogastres were found, some of them typically curled around gorgonian stems. A subsequent closer examination of the Solenogastres revealed another type of object also curled around the gorgonians, which strongly resembled Solenogastres but lacked their external features. These objects proved to be cocoons with egg capsules, each containing two eggs or young larvae, typical of the parasitic platyhelminth group Fecampiida.

Animals↗

PubMed2004

A source-sink hypothesis for abyssal biodiversity.

Bathymetric gradients of biodiversity in the deep-sea benthos constitute a major class of large-scale biogeographic phenomena. They are typically portrayed and interpreted as variation in alpha diversity (the number of species recovered in individual samples) along depth transects. Here, we examine the depth ranges of deep-sea gastropods and bivalves in the eastern and western North Atlantic. This approach shows that the abyssal molluscan fauna largely represents deeper range extensions for a subset of bathyal species. Most abyssal species have larval dispersal, and adults live at densities that appear to be too low for successful reproduction. These patterns suggest a new explanation for abyssal biodiversity. For many species, bathyal and abyssal populations may form a source-sink system in which abyssal populations are regulated by a balance between chronic extinction arising from vulnerabilities to Allee effects and immigration from bathyal sources. An increased significance of source-sink dynamics with depth may be driven by the exponential decrease in organic carbon flux to the benthos with increasing depth and distance from productive coastal systems. The abyss, which is the largest marine benthic environment, may afford more limited ecological and evolutionary opportunity than the bathyal zone.

Animal Migration↗