Lúcia Siqueira Campos

One of the main objectives of the “Program for the Assessment of the Sustainable Potential of Living Resources in the Brazilian Exclusive Economic Zone” (REVIZEE) was to produce a comprehensive inventory of benthic communities off the Brazilian coast. Holothuroid specimens collected at a depth of 246 m off the Rio de Janeiro state were donated for this study. Protankyra estevesi sp. nov. is described and illustrated herein based on morphological characters from a complete specimen and seven posterior fragments. The ossicles were examined using both optical and scanning electron microscopy. Micro-CT imaging was used to explore the calcareous ring elements in detail. The new species has eight long Polian vesicles. The main body wall ossicles consist of anchors and anchor plates, which are smaller anteriorly than posteriorly. Two types of anchor plates are found varying in size and shape. Posterior anchors are 1000 µm in size, and their arm serrations (up to 31) are occasionally discontinuous. Additional body wall ossicles include abundant C-shaped, round, and elongated miliary granules. The calcareous ring is composed of alternating five interradial and five radial pieces; dorsal pieces are shorter than ventral ones. In contrast, RIV and RV are wider than the other radials, each bearing two anterior processes, and the perforation is located in the muscle process. The new species was compared with 37 other congeners distributed worldwide. This is the first report of a deep-sea synaptid species in the southwestern Atlantic off Brazil. There is high potential for marine biodiversity investigations in the region and new species can be revealed not only in newly sampled deep-sea environments but also from studies based on material deposited in zoological collections.

Anthropogenic debris has been documented in Antarctica for the past 40 years. Upon breakdown, large pieces become microdebris, which reaches the seafloor through a variety of physical and biological processes. The Antarctic benthos, deeply reliant on sinking organic particles, is thus vulnerable to ingesting microdebris. By using benthic specimens sampled between 1986 and 2016 and deposited in biological collections, we provide the first record of microdebris in Southern Ocean deep-sea invertebrates. Specimens from 15 species (n = 169 organisms) had their gut content examined, with 13 species yielding microdebris in the shape of fibers (n = 85 fibers). The highest ingestion percentages were recorded in the sea cucumbers Heterocucumis steineni (100%), Molpadia violacea (83%) and Scotoplanes globosa (75%), and in the brittle star Amphioplus peregrinator (53%). Deposit- and suspension-feeding were the strategies which yielded the most fibers, accounting for 83.53% of particles. Seven fibers were identified as microplastics, composed of polyamide, polycarbonate, polyester, polyethylene terephthalate, polyisoprene and polysulfone. We also provide the earliest record of a microplastic in Antarctica, a polysulfone fiber ingested by a Boreomysis sp. mysid caught in 1986. The occurrence of fibers in the world's most remote continental margin renews concerns of pollution in seemingly isolated regions.

Microorganisms dominate most Antarctic marine ecosystems, in terms of biomass and taxonomic diversity, and play crucial role in ecosystem functioning due to their high metabolic plasticity. Admiralty Bay is the largest bay on King George Island (South Shetland Islands, Antarctic Peninsula) and a combination of hydro-oceanographic characteristics (bathymetry, sea ice and glacier melting, seasonal entrance of water masses, turbidity, vertical fluxes) create conditions favoring organic carbon deposition on the seafloor and microbial activities. We sampled surface sediments from 15 sites across Admiralty Bay (100-502 m total depth) and the adjacent North Bransfield Basin (693-1147 m), and used the amplicon 454-sequencing of 16S rRNA gene tags to compare the bacterial composition, diversity, and microbial community structure across environmental parameters (sediment grain size, pigments and organic nutrients) between the two areas. Marine sediments had a high abundance of heterotrophic Gammaproteobacteria (92.4% and 83.8% inside and outside the bay, respectively), followed by Alphaproteobacteria (2.5 and 5.5%), Firmicutes (1.5 and 1.6%), Bacteroidetes (1.1 and 1.7%), Deltaproteobacteria (0.8 and 2.5%) and Actinobacteria (0.7 and 1.3%). Differences in alpha-diversity and bacterial community structure were found between the two areas, reflecting the physical and chemical differences in the sediments, and the organic matter input.

Most species of Taeniogyrus Semper, 1867 are known from shallow water in the Indo-Pacific, with other records in Antarctica, Mediterranean Sea, and the Atlantic. A new species of Taeniogyrus is described and illustrated here from the continental slope of Campos Basin, southeast of Brazil. In this species, sigmoid hooks (336–405 µm) are much larger than in any other in the genus, bearing a long and conspicuous hook region. Wheels with six spokes (86–169 µm), inner margin with 60–125 continuous teeth, are confined to round papillae along each interradius. Polian vesicles are ventral, numerous (15–21), of different sizes, and tubular shaped with a terminal round region. This new species represents the deepest record of the genus Taeniogyrus. It increases to three the number of chiridotids in Brazilian waters, and the number of Taeniogyrus species in the Atlantic. Additionally, Taeniogyrus furcipraeditus (Salvini-Plawen, 1972) from the Mediterranean Sea and Taeniogyrus havelockensis (Rao, 1975) from the Andaman Sea are proposed as new combinations.

Phytoplankton (>15 µm) was investigated in three shallow coastal areas at Admiralty Bay (AB) between the summers of 2002–03 and 2008–09. Phytoplankton abundance was low (10³cells l^-1) and, over time, the prevailing cell size decreased due to a shift in phytoplankton dominant species from diatoms to dinoflagellates.In situand remote sensing data showed that oscillations in sea surface temperature, precipitation, ice formation/melting, irradiance (cloud cover) and bottom circulation (indexed by the Antarctic Oscillation Index; AAO) were shown to govern the structure of the phytoplankton. Under negative AAO, diatoms prevailed, with the dominance of large (>80 µm) benthic diatoms (e.g.Corethron pennatumandNavicula directa) in periods of low production (10²cells l^-1in 2002–03), and medium-sized (31–80 µm) centrics (e.g.Thalassiosiraspp. andStellarima microtrias) when the abundance was higher (10⁴cells l^-1in 2003–04). Conversely, positive AAO led to the co-dominance of dinoflagellates and planktonic diatoms (e.g.Pseudo-nitzschiaspp.) in the summers of 2007–08 and 2008–09. These results suggest that the AAO can be a good predictor of phytoplankton in coastal areas around the western Antarctic Peninsula, and may help our understanding of changes in other trophic levels of the food web.