Nicomache (Loxochona) lokii sp. nov. (Annelida: Polychaeta: Maldanidae) from the Loki’s Castle vent field: an important structure builder in an Arctic vent system

Abstract

The discovery of the Loki's Castle vent field at 2,350 m depth on the Arctic mid-ocean ridge in 2008 represents the first known black smoker vent system in the Arctic region. Preliminary results on the benthic invertebrates collected at Loki's Castle indicate the presence of an endemic fauna dominated by tube-building polychaetes, melitid amphipods and gastropods. Here, we formally describe and investigate the ecological role of a new maldanid species, Nicomache (Loxochona) lokii sp. nov., a species found to be particularly common and regarded as a keystone species in this vent system. The description of the new species is supplemented with a DNA barcode. The subgenus N. (Loxochona) includes at present six nominal species, and the new species described herein is the fourth species associated with reducing habitats. A table with diagnostic characters for all species referred to the subgenus is provided. The new species builds tubes up to a length of 20 cm or more, tightly fastened to the substratum. Together with other tube-building species, N. (L.) lokii sp. nov. form a complex three-dimensional habitat for a number of free-living invertebrates. Based on the morphology of the foregut, the microbial community in the gut and the stable isotope values found for this species, it is concluded that it acts as a grazer in this vent system.

The influence of vent systems on pelagic eukaryotic micro-organism composition in the Nordic Seas

“…4). Sea water and plume chemistry have been investigated thoroughly in other studies (Pedersen et al 2005;Sauter et al 2006;Pedersen et al 2010a;Schander et al 2010;Baumberger 2011;Tandberg et al 2011;Jørgensen et al 2012;Kongsrud and Rapp 2012;Stensland 2013), and further discussion related to chemistry will therefore follow below. Five groups dominated the three different water masses (Alveolata, Rhizaria, Protozoa, Metazoa and Heterokonta), but the internal proportion within a given sample varied.…”

“…Indeed, vent and seep systems can have a high productivity, both benthic and pelagic, compared to the surrounding water masses (Van Dover(2005) and Loki's Castle (2008); in addition, the cold seep Håkon Mosby Mud Volcano was included based on the high methane concentrations in the water column (online resource 2). Since the discovery, several studies (Pedersen et al 2005(Pedersen et al , 2010aLichtschlag et al 2010;Schander et al 2010;Baumberger 2011;Tandberg et al 2011;Jørgensen et al 2012;Kongsrud and Rapp 2012;Stensland 2013) have described the geochemistry, benthic fauna and prokaryote sediment community of both the hydrothermal vents and Håkon Mosby Mud Volcano. However, the protist community in these systems remains largely undescribed despite its importance as a link towards higher trophic levels.…”

Exitomelita sigynae gen. et sp. nov.: a new amphipod from the Arctic Loki Castle vent field with potential gill ectosymbionts

“…The field comprises a number of active black smoker chimneys up to 13 m tall at the top of an extensive mound of hydrothermal sulfide deposits. On the northeastern flank of the mound lies a sedimentary area with low-temperature diffuse venting and small barite chimneys Kongsrud and Rapp 2011).…”

“…Recent expeditions to study the marine biology at Loki's Castle have revealed a completely different picture of Arctic vent ecosystems with the fauna characterized by a high degree of endemism and local adaptation Kongsrud and Rapp 2011) and reveal closer links to Pacific vent faunas compared to vent sites in the Atlantic south of Iceland .…”

Geophysical and geochemical controls on the megafaunal community of a high Arctic cold seep

“…Similarly, high sulfate fluxes were measured at the Beaufort Sea O. haakonmosbiensis site (sulfate concentration decreased from seawater values to <0.1 mmol within 0.5 m of the sediment) (Paull et al, 2015). A dependency on sediment methanotrophic microbes and their activity could also account 15 for the absence of O. haakonmosbiensis at Arctic hydrothermal vents (Kongsrud and Rapp, 2011;Pedersen et al, 2010), despite its wide distribution across the Arctic because at vents, methane rises quickly into the water column due to the heat of hydrothermal emissions, thereby reducing the amount available for sediment microbes.…”