This document contributes to the planning process for the designation of a Domain 1 MPA led by Argentina and Chile. In particular, this paper provides a biodiversity analysis by zone for the Domain 1 MPA preliminary proposal introduced during the last EMM meeting (WG-EMM-17/23; WG-EMM 17/24; WG-EMM-17/25 Rev. 1). Conservation objects comprise different extensions and are distributed differently in Doman 1; while some of them occupy very small areas – such as polynyas – others extend over larger areas -like benthic ecoregions. In general, it may be difficult to protect all spatial features, especially when their distribution is complex. The Domain 1 MPA model was generated based on Priority Areas for Conservation (PAC, SC-CAMLR-XXXVI/17) and taking into consideration the krill fishery and climate change (SC-CAMLR-XXXVI/18). The MPA model achieved the targets for almost 90% of the conservation objects, including the protection for all the areas considered to be important for birds, mammals and fishes. The proposed MPA fulfils the level of protection the international community agreed on for Domain 1. Substantial reductions of this MPA could potentially compromise, at least to some degree, the protection of the conservation objectives established by the Convention, for the designation of MPA in Antarctica.