The comprehensive environmental program conducted by IOM began in 1994 and consisted of two main phases: pre-contract phase (1994 - 2000), and the research which has been carried out after signing the contract for exploration with the International Seabed Authority (2001 to present time).

Pre-contract phase. Baseline studies along the so-called reference transect crossing a considerable portion of the IOM claim area (over 330 km long) were conducted. The in situ Benthic Impact Experiment (so-called BIE) was conducted in 1995 and followed by monitoring of the impact site in 1997 and 2000. During this phase a particular emphasis was given to gather data on physical and chemical oceanography; a total of 14 CTD stations located along the Reference transect were surveyed twice, in 1994 and 1995; near bottom currents were measured over the eight months period at four mooring points. For the first time, macrobenthos in the IOM claim area was studied in 1994 and 1997, and taxonomic identification, densities, and vertical distribution were analysed for seven sediment cores, Epibenthicmegafauna in nodule-bearing and nodule-free areas were examined using the bottom photographs taken along the transects having a common length of about 70 km.

To assess the potential environmental effects of nodule mining, in July 1995 IOM carried out a so-called BIE experiment involving scaled stressing to benthic communities and their habitat. The disturbance was affected by a Deep Sea Sediment Re-suspension System towed on the bottom along 14 tracks laid out within a 2 x 1.5 km test site. Meiobenthos, selected as a key biotic variable with which to assess the effects of disturbance, was sampled at stations distributed randomly in three areas identified as control, impacted, and re-sedimentation areas. Twice, in April 1997 and in June 2000, meiofauna was again analysed using the same sampling strategy. The entire IOM BIE program resulted in the gathering of an extensive data set on the abundance and composition of the meiobenthos; importantly, a very high biodiversity of the two major taxa, nematodes and harpacticoid copepods, was demonstrated at the genus level.

Contract phase. The new phase of the IOM environmental project has started since 2001, after signing a contract with the ISA for the exploration for polymetallic nodules.

According to the contract’s standard clauses, the goal of this study is to gather the environmental baseline data necessary for the determination of the environmental baselines used for assessing the likely effects of mining activities on marine environment.

The IOM carried out three research expeditions in 2001, 2004, and 2009, where sediment samples were retrieved by box-corer from a total of 311 stations; the following parameters of sediments: pH, Eh, grain size, bulk density, water contents, heavy metals, opal and organic matter were all analyzed at specific layers; pore waters from the same sediment layers were also examined for nutrients and metals. Epibenthic megafauna assemblages and its biogenic traces (Lebensspuren) were analysed basing on two sets of images taken in 2001 and 2009 by deep towed camera along 20 transects over a total distance of 607 km. The composition of the megafauna showed that the main part (94%) consisted of 6 taxons (Xenophyophorida, Porifera, Ophiuroidea, Actiniaria, Echinoidea, Holothuroidea); nevertheless, nodule-free seafloor was characterised by a less abundant megafauna (averaging 274 inds/ha) than that inhabiting the nodule-bearing areas (averaging 355 inds/ha). The analysis of the abundance and composition of the macrofauna collected from 11 stations during the IOM’2009 expedition is in progress. Pursuant to the ISA environmental recommendations and guidelines the IOM is currently engaged in classification and systematization of all available data and information on its exploration area marine environment, using the six groups of parameters: ocean physics, ocean chemistry, sediment properties, biological communities, bioturbation and sedimentation.