Publication Date:
2017-03-06
Description:
Leg SO242/2 of an RV SONNE expedition to the DISturbance and reCOLonization (DISCOL) area in
the manganese nodule ecosystem area of the Peruvian Basin in the framework of JPI Oceans
program ‘Ecological aspects of deep-sea mining’ and MIDAS investigated the faunal and
biogeochemical response and recovery to both recent (~5 weeks prior) and historical (~26 yrs prior)
nodule removal and seafloor disturbances. Recently published by MIDAS partners, epifauna studies
conducted within the Clarion Clipperton Fracture Zone (CCZ) as part of the same projects have shown
the potential importance of manganese nodules as suitable hard substrate ‘islands’ onto which stalked
fauna, such as deep sea sponges and crinoids, can settle and develop (Vanreusel et al., 2016).
At the DISCOL site, 27 deep sea incirrate octopi were observed actively feeding around the edges of
Manganese nodules at depths of approx. 4100 m, using crevices between nodules as sites of refuge,
and in two instances brooding eggs directly onto the stalks of dead deep sea fauna. Interestingly, no
incirrate octopi were observed during any of the recent MIDAS / JPI Oceans cruises to the CCZ,
Observed individuals represent at least two species, with several being identified as Vulcanoctopus sp.
The majority appear to belong to the recently observed ‘Casper’ species, recorded by Remote
Operated Vehicles from several locations within the Hawaiian archipelago, and as yet, undescribed.
Together with the recent Hawaiian observations, these new data increase the depth range of incirrate
octopi by several hundreds of meters. Additionally they represent the first observations of incirrate
octopi using other fauna as a brooding substrate.
Though the knock-on impacts on stalk supported small megafauna communities has been a known
consideration for several decades (though better understood following MIDAS and JPI Oceans
investigations) the potential impacts on larger semi-pelagic mobile fauna such as octopi has not been
considered to date. In this study we show that potentially the loss of nodules will have direct impacts
on these larger megafauna. Tantalisingly, the observations of the incirrate octopi in the Hawaiian
archipelago were made in areas also abundant in stalked fauna. Survey dives within these
manganese crust rich regions of seafloor covered considerably less area than the DISCOL work
carried out during SO242/2, and therefore there is the potentiality that stalks in these commercially
interesting ecosystems represent habitat resources at risk from mining activities.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Conference
,
notRev
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