Long term changes in nematode assemblages inhabiting deep-sea fields of polymetallic nodules
Long term changes in nematode assemblages from deep-sea nodule fields
The Clarion-Clipperton Fracture Zone (CCFZ, Tropical NE Pacific) is one of areas perspective for future commercial mining of polymetallic nodules. Nodules contain such valuable metals as Ni, Co, Cu, and deep-sea nodule mining can begin soon. Before commercial mining begins, studies must be conducted to evaluate the possible impact on the sea floor and living communities. First, we should estimate the proportion of biological diversity that will be destroyed by deep-sea mining.
In June 1986, IFREMER initiated a complex survey of a polymetallic nodule formation province located around 14°N 130°W in the CCFZ (NIXO-47 cruise). The data on nematode density and composition of nematode assemblages were reported by Renaud-Mornant & Gourbault (1990). Further, in 2004, the second research cruise NODINAUT took place there, and meiobenthic samples were taken from the same locality. We studied nematodes from these samples and found that nematode assemblages in 2004 were absolutely distinct from ones in 1986 (Miljutina et al., 2010). The differences in composition between the samples might be caused by some long-term environmental changes (by order of decades), such as the supply of organic matter to the seabed, or by high geological activity in the area.
In 2012, new meiobenthic samples were collected from the same locality during the research cruise BIONOD. We study nematode assemblages from these samples and compare them with previous data. The aim is to evaluate long-term changes in nematode communities inhabiting this area of CCFZ in order to distinguish them from possible changes caused by future commercial nodule mining.