Holothuroidea (Echinodermata) of the Peru Basin ‐ Ecological and Taxonomic Remarks Based on Underwater Images

Abstract

The megabenthos plays an important role in the abyssal ecosystem. The holothuroids have been proposed as indicators of physical disturbance of the seabed caused, for example, by commercial deep‐sea mining of manganese nodules. Environmental studies at seabed mining claims have resulted in numerous still photographs that provide an overview of the megabenthos in manganese nodule fields. Data from these investigations and from the large‐scale disturbance and recolonization experiment DISCOL have been used to summarize knowledge of the taxonomy and ecology of holothurians at manganese nodule sites.

Megafauna of the UKSRL exploration contract area and eastern Clarion-Clipperton Zone in the Pacific Ocean: Echinodermata

“…Approximately half of the morphospecies in this atlas have been observed in other contract areas in the CCZ (http://ccfzatlas.com/, Bluhm and Gebruk 1999, Pawson 1983, Pawson and Foell 1986, Tilot 2006), although this may be an overestimate given the presence of cryptic species and the problems identifying megafauna from imagery, as has been experienced during studies in other poorly-explored areas (Amon et al 2016b, Vrijenhoek 2009, Bickford et al 2006, Linse et al 2007). Information like this will likely be crucial to inform the future environmental management of the region.…”

“…The megafauna constitute an important component of the biodiversity in the abyssal deep sea and play a significant role in deep-sea ecosystem function (Amon et al 2016a, Amon et al 2016b, Smith et al 2008, Vanreusel et al 2016). It has also been suggested that echinoderms may act as indicators of physical disturbance of the seabed, such as that caused by deep-sea polymetallic-nodule mining (Bluhm and Gebruk 1999). Glover et al 2016 reported that a search of OBIS listed 698 echinoderm species recorded at abyssal depths worldwide between 3000m and 6000m, but only 50 species within the CCZ.…”

Abundance and Size Distribution Dynamics of Abyssal Epibenthic Megafauna in the Northeast Pacific

“…Work in several regions has provided exploratory descriptions at a particular time and many were initiated to examine the effects of metallic nodule mining and energy industry activities. Regional holothuroid densities in the Pacific seem to be related to the general productivity of the overlying surface waters with the California slope stations having higher-to-similar densities Hamilton 1983, Nybakken et al 1998), and the oligotrophic Peru Basin station having order-of-magnitude lower densities (Bluhm and Gebruk 1999), for instance. The usefulness of photogrammetric methods in deep-sea research has led to megafauna being defined as those organisms large enough (typically !1 cm) to be identified in photographs (Grassle et al 1975).…”

The oldest synallactid sea cucumber (Echinodermata: Holothuroidea: Aspidochirotida)

“…Among these are synallactid holothurians, a group of aspidochirote sea cucumbers that is restricted to the deep water of all oceans today (e.g., Théel 1886;Sluiter 1901;Mitsukuri 1912;Ohshima 1915;Pawson 1965;O'Loughlin and Ahearn 2005) and is characterised by a small to medium size, tube feet, shield-shaped tentacles, lack of tentacle ampullae and specific body-wall ossicles in the form of tables and rods. The family has a cosmopolitan distribution and comprises nearly 140 species in more than 15 genera (Pawson 1982;Solís-Marín 2005, Reich herein); members of the Synallactidae appear frequently as characteristic animals of the abyssal megafauna including tracks and fecal remains (Pawson 1978;Young et al 1985;Bluhm and Gebruk 1999). The majority of synallactid species appear to spend their life on the sediment surface.…”