Megafauna of the UKSRL exploration contract area and eastern Clarion-Clipperton Zone in the Pacific Ocean: Annelida, Arthropoda, Bryozoa, Chordata, Ctenophora, Mollusca

Abstract

BackgroundThere is growing interest in mining polymetallic nodules from the abyssal Clarion-Clipperton Zone (CCZ) in the tropical Pacific Ocean. Despite having been the focus of environmental studies for decades, the benthic megafauna of the CCZ remain poorly known. To predict and manage the environmental impacts of mining in the CCZ, baseline knowledge of the megafauna is essential. The ABYSSLINE Project has conducted benthic biological baseline surveys in the UK Seabed Resources Ltd polymetallic-nodule exploration contract area (UK-1). Prior to ABYSSLINE research cruises in 2013 and 2015, no biological studies had been done in this area of the eastern CCZ.New informationUsing a Remotely Operated Vehicle and Autonomous Underwater Vehicle (as well as several other pieces of equipment), the megafauna within the UK Seabed Resources Ltd exploration contract area (UK-1) and at a site ~250 km east of the UK-1 area were surveyed, allowing us to make the first estimates of megafaunal morphospecies richness from the imagery collected. Here, we present an atlas of the abyssal annelid, arthropod, bryozoan, chordate, ctenophore and molluscan megafauna observed and collected during the ABYSSLINE cruises to the UK-1 polymetallic-nodule exploration contract area in the CCZ. There appear to be at least 55 distinct morphospecies (8 Annelida, 12 Arthropoda, 4 Bryozoa, 22 Chordata, 5 Ctenophora, and 4 Mollusca) identified mostly by morphology but also using molecular barcoding for a limited number of animals that were collected. This atlas will aid the synthesis of megafaunal presence/absence data collected by contractors, scientists and other stakeholders undertaking work in the CCZ, ultimately helping to decipher the biogeography of the megafauna in this threatened habitat.

Ecology of a polymetallic nodule occurrence gradient: Implications for deep‐sea mining

“…To ensure consistency in specimen identification, a CCZ‐standardized megafauna morphospecies catalog was updated from the taxonomic compilation developed by the International Seabed Authority (available online: http://ccfzatlas.com), which we further expanded in consultation with international taxonomic experts and by reference to existing literature (Dahlgren et al ; Glover et al ; Amon et al ; Kersken et al ; Molodtsova et al ). The likely feeding behavior of each morphospecies was inferred from similar organisms described in the literature (e.g., Iken et al ).…”

Observations of deep-sea fishes and mobile scavengers from the abyssal DISCOL experimental mining area

“…Similar studies carried out in the North Pacific have also given indications that seafloor communities have not recovered or only partially recovered in periods of 26-37 years following disturbance (Miljutin et al, 2011;Jones et al, 2017;Gollner et al, 2017). This is not surprising given low rates of recruitment and growth common in these ecosystems and the removal of the hard substrate that a large portion of the fauna depends on (Amon et al, 2016;Vanreusel et al, 2016;Purser et al, 2017).…”

“…Further there are some taxa which can easily be confused depending upon image quality. For instance in the DIS-COL site we identified the ophidiid, Porogadus sp., which has a long whip-like tail and narrow body similar to halosaurs which have been observed in the CCZ (Amon et al, 2017) and in an earlier study at the DISCOL site (Bluhm, 1994). We suspect that with increasing camera resolution and better taxonomic experience, photographic data and their analysis will improve greatly.…”

“…Past studies frequently combined fish and scavenger taxa into larger functional groups such as megafauna (Jones et al, 2017), but some studies have presented lists of species, which are the focus of the comparison here. A number of the fish taxa observed with camera transects in the CCZ (Pawson and Foell, 1983;Radziejewska and Stoyanova, 2000;Tilot, 2006;Amon et al, 2017) have also been identified in the DISCOL area, suggesting large species distributions (Table 3); 10 of the 14 taxa in the DISCOL region are shared with the CCZ. Four taxa were identified from DISCOL that were not previously identified from the CCZ region, none of which were abundant.…”

Detecting the Effects of Deep-Seabed Nodule Mining: Simulations Using Megafaunal Data From the Clarion-Clipperton Zone

“…Numbers of individuals detected rises consistently, the smaller they are, up until this cut-off (Supplementary Figure S2). A megafauna morphospecies catalogue was developed and maintained in consultation with international taxonomic experts and by reference to the existing literature Amon et al, 2017;Molodtsova and Opresko, 2017). Individuals that could not be placed into a morphospecies category were removed from the degradation analysis dataset but were assigned a higherorder identification for their inclusion in overview statistics (e.g., overall metazoan density).…”