New records of demosponges (Porifera) from the South Orkney Islands (Antarctica) with a checklist for the region.

The South Orkney Islands (SOI) is a poorly studied Antarctic archipelago located in the Scotia Arc. In this study, we added 25 Demospongiae species to the SOI known sponge richness, which was previously represented by only 16 species. Of these, 22 species represent new records for SOI region, although they were previously recorded from other Antarctic sectors. Samples were collected during two Argentinean Antarctic Research Cruises onboard RV Puerto Deseado. The most frequently collected species were Artemisina apollinis, Iophon gaussi, I. unicorne, Lissodendoryx (E.) ramilobosa, Myxodoryx hanitschi and Tedania (T.) tantula. Data and illustrations of some rare or uncommon species are provided: Iophon gaussi, Lissodendoryx (E.) anacantha, Microxina charcoti, Raspailia (H.) hentscheli, Haliclona spongiosissima, Haliclona (G.) cf. cucurbitiformis. Although the present results increase substantially the previously known information on sponge species, this is still an underestimation of total richness because certain orders (Tetractinellida, Suberitida, Biemnida, Polymastiida) and classes were not studied during the current investigation, although previous records were included.

Antifouling Diterpenoids from the Sponge Dendrilla antarctica.

Two nor-diterpenes, 9,11-dihydrogracilin A (1) and the previously unreported 9,11-dihydrogracillinone A (2), were isolated from the sponge Dendrilla antarctica. The sponge was collected by trawling at a depth of 49 m, from the research vessel Puerto Deseado, near the coast of Tierra del Fuego, farther north than the reported habitat for this species. Since these compounds were particularly abundant and the sponge was free from epibionts, both 1 and 2 were included in soluble-matrix paints and tested for antifouling activity in the ocean. The results obtained from these experiments clearly indicated a potent antifouling activity for both compounds against a variety of colonizing organisms, and established a probable role as natural antifoulants for these abundant secondary metabolites and other structurally related compounds previously isolated from Dendrilla spp.

Polychaetes from Burdwood Bank: "Namuncurá I" Marine Protected Area and slope, SW Atlantic Ocean

Introduction: The first open-sea (non-coastal) Marine Protected Area in Argentina, named "Namuncurá I" (NMPA), was created in 2013 at Burdwood Bank (BB), an undersea plateau located about 200 km south from Malvinas Islands (Falkland Islands) and 150 km east from Staten Island, SW Atlantic Ocean. It comprises three different management areas: the central one ("core", strict protection, only control and monitoring activities), surrounded by a "buffer" area (authorized activities, e.g. scientific research) and an external "transition" area (productive and extractive activities contemplated in the Management Plan). Beyond the transition area, only the southern shelf-break is protected, after the creation of the "Namuncurá II" MPA in December 2018. Objective: Provide the inventory of polychaetes collected during 2016 and 2017 at the core (98 m depth), buffer (128 m depth), transition (133 m-189 m depth) areas of the Namuncurá I MPA, together with slope areas (220 m-798 m depth). Methods: Taken with a trawl net used to characterize the faunal assemblages and to compare results with other Magellan areas. Multidimensional Scaling (MDS) and Cluster Analysis (CA) were applied to a Bray-Curtis similarity index to assess polychaete assemblages in the NMPA - BB slope and Magellan region respectively; SIMPER (Similarity Percentage Analyses) and ANOSIM (Analysis of Similarities) were performed. Results: A total of 918 individuals, which correspond to 39 taxa distributed in 22 families, were recorded in samples from NMPA and BB slope, mainly epibenthic or associated with the large corals collected. Ampharete kerguelensis McIntosh, 1885; Hyalinoecia artifex Verrill, 1880; Idanthyrsus macropaleus (Schmarda, 1861); Laetmonice producta Grube, 1877; Onuphis pseudoiridescens Averincev, 1972; Pista mirabilis McIntosh 1885 and Terebellides malvinensis Bremec & Elias, 1999 constitute new records for Burdwood Bank. A similar polychaete assemblage characterized the three areas of NMPA and slope locations, while H. artifex characterized locations at the NW deepest slope of the bank. Conclusions: These results indicate strong connections between the fauna collected at NMPA and the polychaetes assemblage in other Magellan areas dominated by soft bottoms. The biogeographic importance of the BB as connection for benthic polychaete species between South America and the Antarctic Peninsula merits future investigation.

Introducción: La primera Área Marina Protegida de mar abierto (no costera) en Argentina, llamada "Namuncurá I" (AMPN), fue creada en 2013 en el Banco Burdwood (BB), una plataforma sumergida ubicada unos 200 km al sur de las Islas Malvinas y 150 km al Este de la Isla de los Estados. En el Océano Atlántico SO. El área comprende tres diferentes áreas de manejo: la central ("el núcleo", con protección estricta, solo Control y actividades de monitoreo), rodeada por un área "de amortiguación" (solo actividades autorizadas, como investigación científica) y un área externa de "transición" (se contemplan actividades productivas y extractivas en el Plan de Manejo). Más allá del área de transición, el talud y las áreas adyacentes no presentan medidas de protección. Objetivos: Proporcionar un inventario de poliquetos colectados durante 2016 y 2017 en el Núcleo (98 m de profundidad), de Amortiguación (128 m), de Transición (133 m-189 m) y Talud (220 m-798 m). Métodos: Las muestras fueron obtenidas con una red de arrastre para caracterizar las asociaciones faunísticas y para compararlas con otras áreas Magallánicas. Análisis de Escalamiento Multidimensional y de agrupamiento aglomerativo jerárquico fueron aplicados a una matriz de similaridad de Bray-Curtis para determinar las asociaciones de poliquetos en el AMP - Talud del BB y región Magallánica, respectivamente. Resultados: Un total de 918 individuos, que corresponden a 39 taxones distribuidos en 22 familias, fueron registrados en las muestras del AMPN y talud del BB, mayormente epibentónicos o asociados a grandes corales. Ampharete kerguelensis McIntosh, 1885; Hyalinoecia artifex Verrill, 1880; Idanthyrsus macropaleus (Schmarda, 1861); Laetmonice producta Grube, 1877; Onuphis pseudoiridescens Averincev, 1972; Pista mirabilis McIntosh 1885 y Terebellides malvinensis Bremec & Elias, 1999 constituyen nuevos registros para el Banco Burdwood. Un ensamble de poliquetos similar caracteriza a las tres áreas del AMPN y talud, mientras que H. artifex caracteriza los sitios más profundos del talud del banco. Conclusiones: Estos resultados indican una fuerte conexión entre la fauna colectada en el NMPA y los ensambles de poliquetos de sustratos blandos de otras áreas Magallánicas. La importancia biogeográfica del BB como una conexión entre Sudamérica y la Península Antártica justifican futuras investigaciones.

Chaetopterus antarcticus (Polychaeta: Chaetopteridae) in Argentinian shelf scallop beds: from infaunal to epifaunal life habits

Introduction: The shelf-break frontal area in the Argentine Sea, between 37ｼ S and 40ｼ S, is characterized by high frequency and abundance of the parchment worm Chaetopterus antarcticus Kinberg, 1866 associated to Zygochlamys patagonica scallop beds. This polychaete was usually collected within its U tubes, typical of infaunal habit. During 2007, a surprising massive settlement of worms on scallops was observed. Objective: Our objectives is to report the variability of life habits of C. antarcticus in scallop grounds distributed between 37º S and 40º S in Argentinean waters. Methods: The presence of the parchment tube worms on Z. patagonica was analyzed in 892 scallops coming from three samples collected in September (previously obtained for other purposes) and November 2007 and April 2008, between 99-106 m depth in Management Unit B (16.186 km2, 38º S - 39º 52' S). Polychaetes were identified and quantified on both valves. In addition, both epibiont and infaunal worms were registered through time. The settlement of C. antarcticus on scallops was monitored during the period 2007-2015 and the presence of free tubes, both empty and inhabited by worms, were registered during the period 2008-2015 from a total of 374 representative subsamples (10 l) collected with trawling tools between 37º S and 40º S. Results: Scallops collected in 2007 and 2008 showed that 468 (> 50 %) specimens were encrusted; in 66 % (311 specimens) of them C. antarcticus was settled. The temporal analysis showed that the spatial distribution of epibiotic worms decreased in 2009, 2010 and 2012, with its total absence in 2013, 2014 and 2015 in the study area. During the period 2007 - 2015, infaunal worms were registered throughout the area, collected in part of the locations monitored. Conclusions: The variability of life habits of C. antarcticus was not commonly registered previously in the study area; epibiotic behavior could be the result of intensive soft sediment disturbance due to trawling and hence, the selection of other available primary settlement substrate.

Introducción: El área del frente de talud en el Mar Argentino, entre 37° S y 40° S, se caracteriza por alta frecuencia y abundancia del poliqueto Chaetopterus antarcticus Kinberg, 1866 asociado a bancos de vieira Zygochlamys patagonica (King, 1832). Este poliqueto era colectado usualmente habitando los tubos en U, típicos de hábito infaunal. Durante 2007, un sorprendente asentamiento masivo de gusanos sobre vieiras fue observado. Objetivos: Los objetivos del trabajo son reportar la variabilidad del hábito de vida de C. antarcticus en fondos de vieiras entre 37° S y 40° S en aguas de Argentina. Métodos: La presencia de gusanos tubícolas sobre Z. patagonica se analizó en 892 vieiras colectadas en tres muestras durante Septiembre (muestra tomada con otros propósitos) y Noviembre 2007 y Abril 2008, entre 99-106 m de profundidad en la Unidad de Manejo B (16.186 km2, 38º S - 39º 52' S). Los poliquetos fueron identificados y cuantificados en ambas valvas. Además, los gusanos tanto epibiontes como infaunales se registraron en un período de tiempo. El asentamiento de C. antarcticus sobre vieiras se monitoreó durante 2007-2015 y la presencia de tubos libres, tanto vacíos como habitados por gusanos, durante 2008-2015 a partir de 374 submuestras representativas (10 l) colectadas con artes de arrastre entre 37° S y 40° S. Resultados: Las vieiras colectadas en 2007 y 2008 mostraron que 468 (> 50 %) especímenes estaban incrustados; C. antarcticus estaba asentado en 66 % (311 especímenes) de los mismos. El análisis temporal mostró que la distribución espacial de gusanos epibiontes decreció en 2009, 20101 y 2012, y su ausencia total en 2013, 2014 y 2015 en el área de estudio. Durante el período 2007 - 2015 los gusanos infaunales se registraron en toda el área, en parte de las localidades relevadas. Conclusiones: La variabilidad del hábito de vida de C. antarcticus no había sido registrada previamente en el área de estudio; el comportamiento epibiótico podría ser el resultado del disturbio intensivo de los sedimentos blandos debido al arrastre y en consecuencia, la selección de otro sustrato de asentamiento primario disponible.

Isolation and Antifouling Activity of Azulene Derivatives from the Antarctic Gorgonian Acanthogorgia laxa.

Three azulenoid sesquiterpenes (1 - 3) were isolated from the Antarctic gorgonian Acanthogorgia laxa collected by bottom trawls at -343 m. Besides linderazulene (1), and the known ketolactone 2, a new brominated C16 linderazulene derivative (3) was also identified. This compound has an extra carbon atom at C(7) of the linderazulene framework. The antifouling activity of compounds 1 and 2 was assayed in the laboratory with Artemia salina larvae, and also in field tests, by incorporation in soluble-matrix experimental antifouling paints. The results obtained after a 45 days field trial of the paints, showed that compounds 1 and 2 displayed good antifouling potencies against a wide array of organisms. Compound 3, a benzylic bromide, was unstable and for this reason was not submitted to bioassays. Two known cembranolides: pukalide and epoxypukalide, were also identified as minor components of the extract.

Isolation of acetylated bile acids from the sponge Siphonochalina fortis and DNA damage evaluation by the comet assay.

From the organic extracts of the sponge Siphonochalina fortis, collected at Bahía Bustamante, Chubut, Argentina, three major compounds were isolated and identified as deoxycholic acid 3, 12-diacetate (1), cholic acid 3, 7, 12-triacetate (2) and cholic acid, 3, 7, 12-triacetate. (3). This is the first report of acetylated bile acids in sponges and the first isolation of compound 3 as a natural product. The potential induction of DNA lesions by the isolated compounds was investigated using the comet assay in lymphocytes of human peripheral blood as in vitro model. The results showed that the administration of the bile acid derivatives would not induce DNA damages, indicating that acetylated bile acids are nontoxic metabolites at the tested concentrations. Since the free bile acids were not detected, it is unlikely that the acetylated compounds may be part of the sponge cells detoxification mechanisms. These results may suggest a possible role of acetylated bile acids as a chemical defense mechanism, product of a symbiotic relationship with microorganisms, which would explain their seasonal and geographical variation, and their influence on the previously observed genotoxicity of the organic extract of S. fortis.

Dolabellane Diterpenoids from the South Atlantic Gorgonian Convexella magelhaenica.

Two new dolabellane diterpenoids (1 and 2) were isolated from a small sample of the deep water gorgonian octocoral Convexella magelhaenica collected as a nontarget by-catch by dredging (-93 m) in commercial Patagonian scallop fishing grounds in the South Atlantic. The structures of the new compounds, which are major metabolites in the extract, were established by spectroscopic techniques and chemical transformations. Both compounds were cytotoxic against a human pancreatic adenocarcinoma cell line at micromolar concentrations.