Abstract
Marine biogenic skeletal production is the prevalent source of Ca-carbonate in today’s Antarctic seas. Most information, however, derives from the post-mortem legacy of calcifying organisms. Prior imagery and evaluation of Antarctic habitats hosting calcifying benthic organisms are poorly present in the literature, therefore, a Remotely Operated Vehicle survey was carried out in the Ross Sea region Marine Protected Area during the 2013–2014 austral summer. Two video surveys of the seafloor were conducted along transects between 30 and 120 m (Adelie Cove) and 230 and 260 m (Terra Nova Bay “Canyon”), respectively. We quantified the relative abundance of calcifiers vs. non-calcifiers in the macro- and mega-epibenthos. Furthermore, we considered the typology of the carbonate polymorphs represented by the skeletonized organisms. The combined evidence from the two sites reveals the widespread existence of carbonate-mixed factories in the area, with an overwhelming abundance of both low-Mg and (especially) high-Mg calcite calcifiers. Echinoids, serpulids, bryozoans, pectinid bivalves and octocorals prove to be the most abundant animal producers in terms of abundance. The shallower Adelie Cove site also showed evidence of seabed coverage by coralline algae. Our results will help in refining paleoenvironmental analyses since many of the megabenthic calcifiers occur in the Quaternary record of Antarctica. We set a baseline to monitor the future response of these polar biota in a rapidly changing ocean.
Highlights
The Ross Sea region Marine Protected Area (RSRMPA) encompasses a surface of ca. 1.55 million km2, which represents the world’s largest marine protected area established under an international agreement to date
Up to 100 m depth, the seafloor was characterized by a dense coverage from coralline algae of the order Hapalidiales (Figure 3A–C)
Cove reveals reveals the the occurrence occurrence of of four four main main The calcifiers in the order of relative abundance: Hapalidiales coralline algae, which predomcalcifiers in the order of relative abundance: Hapalidiales coralline algae, which predominates in in the the shallower shallower part part of of the the transect transect
Summary
Licensee MDPI, Basel, Switzerland.Attribution (CC BY) license (https://creativecommons.org/licenses/by/The majority of studies concerning Antarctic marine carbonates rely upon outcrop, seafloor and core sediment sample evidence (e.g., [1,2,3,4,5,6,7,8,9,10]). On the contrary, little visual information on their source factories is available and this is particularly true regarding deep-sea habitats. Seafloor imagery (photos and videos) documenting benthic habitats within the reach of scuba diving abound (e.g., [11,12,13,14,15,16,17,18,19]), whilst considerably fewer studies imaged habitats from 50 m down to bathyal depths [20]. The geo-referenced transects by means of towed cameras are equally scant (e.g., [21,22,23,24]). The utilization of Remotely
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