Contribución INIDEP 2444
Chiaverano, Luciano M.; Sobrero, Lucila; Dato, Claudia V.; Schiariti, Agustín. (2025).

Spatio-temporal variability in medusa biomass linked to oceanographic conditions in a productive shelf ecosystem of the Southwestern Atlantic. Journal of Marine Systems
251:104122 https://doi.org/10.1016/j.jmarsys.2025.104122

Abstract
This study presents the first large-scale, long-term ecological assessment of a large pelagic cnidarian (Aequorea forskalea) within a highly productive and economically significant marine area of the Southwestern Atlantic. Using nearly three decades of summer fishery survey data (1995-2024), we evaluated the spatial and temporal variability of Aequorea biomass and its relationship with oceanographic conditions. Biomass distribution was spatially structured, concentrating in the San Jorge Gulf, a temporally persistent hotspot of biomass. A major shift in biomass occurred in 2011, marking a transition from a high-biomass phase (1995-2010) to a period of low biomass (2011-2024), coinciding with rising bottom temperatures and decreasing salinity in hotspot areas. Given the spatio-temporal overlap with early life stages of key fisheries species (Argentine hake and Patagonian red shrimp), Aequorea may influence recruitment dynamics through predation and competition. These findings underscore the importance of integrating biological and physical data to understand gelatinous zooplankton dynamics. Long-term fisheries surveys are shown to be valuable sources of baseline data, essential for predicting ecosystem responses to environmental change.

Contribución INIDEP 2445
Greer, A.; Chiaverano, Luciano M. (2025).

Oceanographic structure facilitates gelatinous zooplankton niche space and diversity. Limnology and Oceanography Letters 11(1):e70083
https://doi.org/10.1002/lol2.70083

Abstract
Gelatinous zooplankton serve diverse ecological roles in shelf food webs-from grazers to predators. However, their spatial niches are poorly resolved, especially at detailed taxonomic levels, due to conventional techniques that are unable to measure distributions at fine spatial scales. Seasonal in situ imaging transects across the dynamic northern Gulf of Mexico demonstrated that taxonomic diversity of gelatinous zooplankton increases with stratification and habitat heterogeneity. Taxa displayed low spatial niche overlap (~10 percent, Schoener's D), independent of season (stratified, river-influenced, and well mixed), and even when associated with similar water mass properties. This suggests that oceanography structures the distributions of gelatinous organisms and water mass preferences, but ecological interactions among taxa generate distinct taxon-specific spatial niches. Although automated image classification algorithms currently prioritize broad taxonomic groups, detailed identifications and improved resolution of interactions (predator-prey, competition, etc.) may underlie a predictive framework for gelatinous abundances and diversity.

Contribución INIDEP 2447
Di Mauro, Rosana; Alves, Nadia M.; Rodríguez, Julieta; Sobrero, Lucila; Chiesa, Ignacio Luis; Hozbor, M. Constanza; Allega, Lucrecia; Antacli, Julieta C.; Díaz, Marina Vera; Schiariti, Agustín. 2025.

Assessing anthropogenic microfiber pollution in the southwestern Atlantic Ocean: a large-scale study on spatial distribution, concentration and physical characterization. Environmental Science and Pollution Research 32:22458-22478
https://doi.org/10.1007/s11356-025-36964-6

Abstract
This study presents the first large-scale assessment of anthropogenic microfiber (AMF) pollution in surface waters (~?5-m depth) of the Southwestern Atlantic Ocean (SWAO), covering an extensive area of approximately 1.2 million km2, spanning coastal, shelf, and shelf-break regions, in a latitudinal range from 34°S to 56°S. A total of 102 water samples were collected during seven fisheries and environmental research cruises, targeting key fishing grounds and Marine Protected Areas. AMFs were found to be ubiquitous throughout the region, with the highest concentrations detected in estuarine zones adjacent to major urban centers. Remarkably, additional hotspots were identified in offshore and remote shelf-break areas, indicating the role of long-range transport and oceanographic retention processes in their accumulation. Evidence of environmental weathering-such as discoloration, fraying, and biofouling-was more prevalent at offshore sites, supporting the hypothesis of prolonged residence and dispersal within the marine environment. AMFs displayed considerable variability in shape, color, and size, with many exhibiting morphological traits typical of textile-derived materials. Given the potential ecological risks, this study highlights the importance of addressing AMF pollution in ecologically productive marine areas, where interactions with marine organisms are more likely.

Contribución INIDEP 2451
Epherra, Lucía; Castro, Karen L.; Arijon, Marianela; Rubilar, Tamara; Morsan, Enrique. (2025).

Feeding preference of the native sea urchin Arbacia dufresnii in an environment invaded by the kelp Undaria pinnatifida. Revista del Museo Argentino de Ciencias Naturales. Nueva serie 27(1):33-41
https://revista.macn.gob.ar/index.php/RevMus/article/view/867

Abstract
In Argentina, the invasive kelp Undaria pinnatifida has modified the benthic community of Nuevo Gulf, northern Patagonia, where it was first recorded and is currently showing advanced invasion. Arbacia dufresnii, an abundant generalist omnivore sea urchin, has fully incorporated U. pinnatifida into its diet. Since sea urchins can influence the structure and dynamics of benthic macroalgal assemblages, determining the importance of U. pinnatifida in the feeding preferences of A. dufresnii complements the evaluation of the modifications caused by this species. Thus, this study aimed to assess the feeding preference of A. dufresnii in an environment invaded by U. pinnatifida. We conducted feeding experiments to determine whether A. dufresnii feeds on different developmental stages of U. pinnatifida, and preference experiments of this invasive species against six macroalgal species abundant in the environment. Arbacia dufresnii consumed both blades and sporophylls of U. pinnatifida at all the developmental stages evaluated, showing a preference for blades over sporophylls. Arbacia dufresnii showed preference for U. pinnatifida only when it was offered together with species that possess defense mechanisms against herbivory. The lack of preference for other macroalgae species over U. pinnatifida suggests that this invasive species may alter resource use and thereby affect the trophic structure of native communities. These findings complement previous diet studies, corroborating the feeding plasticity of A. dufresnii, as well as its ability to adapt to newly available resources. This research enhances the understanding of the impacts caused by invasive macroalgal species through feeding ecology studies of native grazers.

Contribución INIDEP 2452
Martínez, Mariano; Tablado, Alejandro; Scarabino, Fabrizio; Romanelli, Mariela; Pfoh, Malena; Pertossi, Renata; Pérez, Analía; Penchaszadeh, Pablo E.; Lauretta, Daniel; Huenten, Daniela; Gil, Damián; Fraysse, Cintia; Flores, Jonathan; Epherra, Lucía; Di Marco, Florencia; Arribas, Lorena; Alarcón Saavedra, Ariana; Brogger, Martín. (2025).

A century of echinoderm research in Argentina: Irene Bernasconi´s lasting legacy from 1925, with notes on type material and publication chronology. Revista del Museo Argentino de Ciencias Naturales. Nueva serie 27(1):1-17
https://revista.macn.gob.ar/index.php/RevMus/article/view/913

Abstract
Irene Bernasconi was the pioneering and world-wide recognized echinoderm specialist from Argentina. Her career, spanning nearly six decades, was marked by significant contributions to the taxonomy of echinoderms mainly from southwestern Atlantic and Antarctic Peninsula and laid the foundation for the inclusion of women in science in her country. Based honorary at the Museo Argentino de Ciencias Naturales "Bernardino Rivadavia" (MACN) and later as a CONICET researcher, Bernasconi contributed to the description of 25 new taxa (3 subspecies, 21 species, 1 genus). This review addresses the status of the species she described, including nomenclatural updates and compiles her extensive publication record of 68 research articles, highlighting her focus on asteroids (60 percent of her studies), echinoids (32 percent), and ophiuroids (26 percent), with minor contributions to crinoids and holothuroids (3 percent for both). The first publication by Bernasconi appeared in 1925, and her final work was completed in 1980, reflecting her valuable commitment to echinoderm studies as a cornerstone in the region.

Contribución INIDEP 2453
González-Delgado, Sara; Sosa, Naira; Epherra, Lucía; Hernández, Celso A.; Hernández, José C. (2025).

What doesn't kill you makes you stronger: the sea urchin Arbacia lixula living on volcanic CO2 vents. Marine Environmental Research 212:107495
https://doi.org/10.1016/j.marenvres.2025.107495

Abstract
Anthropogenic CO2 emissions drive ocean acidification (OA), which reduces seawater pH and carbonate ion availability, threatening calcifying organisms such as sea urchins. This study examines the long-term effects of OA on Arbacia lixula using a natural volcanic CO2 vent at Fuencaliente, La Palma (Canary Islands) as an analogue of future conditions. We analyzed the external morphology, skeletal strength, mineralogy, and growth of A. lixula across three sites that differed consistently in mean pH (from 8.14 to 7.65 during low tide). Sea urchins from low pH conditions were smaller, with shorter spines and reduced jaw-to-diameter ratios, yet their tests showed higher fracture resistance than those from ambient conditions. Additionally, individuals from acidified zones showed altered growth dynamics, with fewer growth rings. Skeletal changes and growth alterations are consistent with modified mineralization processes and dietary shifts toward non-calcareous food sources. This study highlighting the morphological plasticity and resilience of A. lixula under persistent natural acidification, offering insight into how sea urchins may respond in a high-CO2 ocean.

Contribución INIDEP 2456
Segueira, Ana M.M.; Rodríguez, Jorge P.; Marley, Sarah A.; Calich, Hannah J.; van der Mheen, Mirjam; et al.; González Carman, Victoria; et al. (2025).

Global tracking of marine megafauna space use reveals how to achieve conservation targets. Science 388(6751):1086-1097
https://doi.org/10.1126/science.adl0239

Abstract
The recent Kunming-Montreal Global Biodiversity Framework (GBF) sets ambitious goals but no clear pathway for how zero loss of important biodiversity areas and halting human-induced extinction of threatened species will be achieved. We assembled a multi-taxa tracking dataset (11 million geopositions from 15,845 tracked individuals across 121 species) to provide a global assessment of space use of highly mobile marine megafauna, showing that 63 percent of the area that they cover is used 80 percent of the time as important migratory corridors or residence areas. The GBF 30 percent threshold (Target 3) will be insufficient for marine megafauna's effective conservation, leaving important areas exposed to major anthropogenic threats. Coupling area protection with mitigation strategies (e.g., fishing regulation, wildlife-traffic separation) will be essential to reach international goals and conserve biodiversity.

Contribución INIDEP 2458
Guinder, Valeria A.; Tillmann, Urban; Rivarossa, Martín J.; Ferronato, Carola; Ramírez, Fernando J.; Krock, Bernd; Gu, Haifeng; Saraceno, Martín. (2025).

Extraordinary bloom of toxin-producing phytoplankton enhanced by strong retention on the offshore Patagonian shelf. Biogeosciences 22(13):3397-3428
https://doi.org/10.5194/bg-22-3397-2025

Abstract
The extensive Patagonian continental shelf in the Atlantic Ocean is renowned for its high productivity associated with nutrient-rich waters that fertilize massive phytoplankton blooms, especially along the shelf-break frontal system. Growing evidence reflects this ecosystem as a hotspot for harmful algal blooms (HABs). Whether these HABs reach coastal areas or are exported to the adjacent ocean basin by energetic edge currents remains unexplored. During two oceanographic cruises in spring 2021, a bloom of dinoflagellates of the Amphidomataceae family was sampled over the outer shelf with a 10?d interval, at stations 40?km apart. The bloom was first sampled on 16 November, with 32 ×106 cells L-1, and was still persistent on 25 November, with 14 ×106 cells L-1. The magnitude of this bloom is a global record for this group so far reported in the literature. The toxin azaspiracid-2 (AZA-2) was detected in both stages of the bloom, with values up to 2122 pg?L-1. The most likely source of AZA-2 was Azadinium spinosum ribotype B. The bloom developed in vertically stable waters (60 m mixed layer depth) with elevated chlorophyll concentration. Water retention and the presence of fronts induced by horizontal stirring controlled the persistence and trajectory of the bloom in a localized area over the continental shelf, as evidenced by analysis of geostrophic surface currents, Lyapunov coefficients, and particle advection modelling. These findings underscore the importance of monitoring HABs in offshore environments and the need to understand biophysical interactions that govern bloom taxa assemblages and transport pathways.

Contribución INIDEP 2461
Novillo, Manuel; Moreira, Eugenia; La Mesa, Mario; Macchi, Gustavo J.; Barrera Oro, Esteban. (2026).

Reproductive biology of Trematomus hansoni (Nototheniidae) in the West Antarctic Peninsula reveals inshore spawning. Estuarine, Coastal and Shelf Science 328:109598
https://doi.org/10.1016/j.ecss.2025.109598

Abstract
Understanding the reproductive strategies of Antarctic notothenioids is essential for assessing their vulnerability to environmental change. This study provides evidence of inshore spawning in the striped notothen Trematomus hansoni off the West Antarctic Peninsula (WAP), based on macroscopic and histological analyses of gonads from specimens collected in Paradise Bay during austral summer 2019, 2023 and 2025. Gravid females display a group-synchronous ovarian development organization and a total spawning strategy, releasing large yolked oocytes (2.1-4.7 mm) in a single event during the spawning season. Post-ovulatory follicles and hydrated oocyte expulsion confirm that spawning occurs in late January-February in shallow coastal waters. The simultaneous presence of ripe males with mature spermatozoa indicates a synchronous reproductive period. The positive allometric growth observed in T. hansoni suggests a capital breeding strategy, consistent with ecological adaptations to the highly seasonal polar environment. Reproductive traits closely matched values from other Antarctic populations, although regional differences were observed in fecundity and gonadal investment. Our results align with documented evidence that several notothenioids species use nearshore habitats for reproduction. Given the WAP status as one of the fastest-warming regions on Earth, these findings highlight the ecological significance and vulnerability of inshore habitats. As temperature-driven changes may disrupt spawning timing and success, long-term monitoring of reproductive patterns is essential. The present study also underscores the need to consider inshore ecosystems in Antarctic fish population's conservation and management efforts.

Contribución INIDEP 2463
Segura, Valeria; del Valle, Daniela A.; Lutz, Vivian A.; Luz Clara Tejedor, Moira; Silva, Ricardo I.; Fernández Acuña, Jorge M.; Ruiz, M. Guillermina; Allega, Lucrecia; Berghoff, Carla F.; García Facal, Guillermina; Epherra, Lucía. (2026).

Seasonal primary production at the EPEA station, southwestern Atlantic: relationships with phytoplankton composition and environmental properties. Marine and Fishery Sciences 39(1)
https://doi.org/10.47193/mafis.3912026010104

Abstract
This study presents the first estimates of primary production (PP) from the Marine Ecological Time Series, Estación Permanente de Estudios Ambientales (EPEA) in the Argentine Sea and examines its relationship with phytoplankton community composition and environmental factors using data obtained between 2006 and 2019. Our findings indicate that PP at EPEA exhibits seasonal pulses, with an estimated annual average of 202 ± 115 g C m-2 yr-1, classifying the system as mesotrophic. The peak of PP occurred in spring associated with increased irradiance and water column stratification, and the dominance of diatoms, dinoflagellates, and haptophytes. Winter was the least productive season, characterized by low light levels and a deep mixed layer, with a prevalence of cryptophytes and ultraphytoplankton. In summer, PP was lower than in spring, and the community was dominated by picoplanktonic Synechococcus spp., adapted to low nutrients and high light. In autumn, PP increased relative to summer, associated with higher microphytoplankton biomass. A key finding was the decoupling between PP and total carbon biomass, highlighted by the high variability of the BC to ChlaS (BC/ChlaS) ratio. This ratio is crucial for linking carbon-based biogeochemical models with satellite-based PP models. Deviations from the expected seasonal patterns could point to the sensitivity of coastal PP to large-scale climate influences, such as the Southern Annular Mode (SAM) and the El Niño-Southern Oscillation (ENSO). Our results evidence the physiological adaptability of phytoplankton in this dynamic coastal environment and highlight the necessity of high-frequency sampling to improve primary productivity models in this under-sampled region.

Contribución INIDEP 2468
Schejter, Laura; Escolar, Mariana; Roth, Ricardo R.; García, Julio; Campodónico, Silvana. (2026).

In situ imaging of benthic fauna of the argentine shelf break front, SW Atlantic Ocean. Latin American Journal of Aquatic Research 54(1)
https://www.lajar.cl/index.php/rlajar/article/view/vol54-issue1-fulltext-3436

Abstract
his study presents the first in situ images of benthic invertebrates and fishes inhabiting the shelf break front of Argentina, in the SW Atlantic Ocean. Obtained over a soft-sandy substrate, these images represent the first live visual records of several species of invertebrates and fish commonly found in this area, where the Patagonian scallop (Zygochlamys patagonica), the Argentine hake (Merluccius hubbsi), and the Argentine squid (Illex argentinus) fishery fleet operate. These images reveal the structure of these very rich benthic communities, in which echinoderms, mainly ophiuroids, are one of the dominant groups.

Contribución INIDEP 2470
Martínez, Ana; Silva, Ricardo I.; Ruiz, M. Guillermina; Montoya, Nora G.; Molinari, Graciela N. (2025).

Distribución espacial del microplancton (200 µm) autótrofo en la Zona Común De Pesca (ZCP) argentino-uruguaya durante diciembre de 2019. Frente Marítimo 27:12-21

Abstract
The composition of the plankton community not only influence on the trophic web but also on gas exchange (production-respiration) and consequently on climate. Microscopy, flow cytometry and HPLC were used to analyze the phytoplankton community from samples collected during survey VA1219 in December 2019. Predominance of different groups in relation with distinct areas of the Common Fishing Zone was recorded. In the southern transect, off Mar del Plata, components of the pico-ultraplankton dominated the community in terms of biomass. Low biomass, comprising all plankton sizes, was registered in the coastal region of the transect, whereas in mid-shelf waters it was made up exclusively of Synechococcus and in deeper waters of haptophytes of the ultraphytoplankton (in coincidence with high concentrations of 19´- hexanoyl oxi-fucoxanthin (Hex-fuco), and by dinoflagellates of the nanophytoplankton. In the inner part of the central transect, off Rio de la Plata (RP04 a RP07) the community was represented by fractions of the nano-microphytoplankton, such as diatoms and euglenophyceae. This dominance of diatoms of the nano-microphytoplankton was also observed in the costal stations of the northern transect, off La Paloma, where a bloom of Chaetoceros dydimus and high abundance of Thalassionema nitzschioides and Rhizosolenia setigera were recorded. In the intermediate sector of the Rio de la Plata transect, where the water column was stratified, blooms of dinoflagellate of various sizes were recorded. In deeper waters, the dominant genus was Azadinium, coinciding with a high concentration of peridinin, whereas in surface waters Oxytoxum laticeps and Karenia sp. prevail, co-ocurring with higher concentrations of Hex-fuco. In the outer sectors of the Rio de la Plata and La Paloma transects, where small sized phytoplankton dominated, high abundance of cocolithophoridae and picophytoplankton, mainly Prochlorococcus were registered, coinciding with divynil clorophyll a. The spatial distribution of the phytoplankton community was related to the differents water masses in the ZCP.

Contribución INIDEP 2471
Luz Clara Tejedor, Moira; Maenza, Reinaldo Agustín; Prario, Bárbara E. (2025).

Análisis de olas de calor marinas en la Zona Común de Pesca argentino-uruguaya (ZCP) en la era satelital (1982-2021). Frente Marítimo 27:22-25

Abstract
Events characterized by elevated sea surface temperature (SST), known as marine heatwaves (MHW), usually have an impact on biodiversity patterns and ecosystems, by inducing rapid environmental changes and impacting the habitat of diverse species. MHWs can be defined as anomalously warm and discrete events lasting five or more consecutive days. Given that MHWs are generally a consequence of high air temperature, impacts are typically limited to the upper water column, and the degree of ecosystem disturbance varies according to the temperature magnitude reached, event duration, frequency, or combinations thereof. This study analyzed the interannual variability of MHWs across different seasons within the ZCP for the period 1982-2021, examining gridded data from the second version of the NOAA Reynolds Optimum Interpolation Sea Surface Temperature dataset (OISST v2), derived from a combination of satellite observations and in situ (research vessels, buoys, etc.) sampling. A daily temporal resolution and a spatial resolution of 0.25º latitude by longitude were employed. The study identified areas with statistically significant linear trends for several quantitative indices of duration and the intensity of these events, revealing an increase in these parameters, mainly during austral spring (October through December) and austral summer (January through March) seasons, across a substantial portion of the ZCP, particularly since the beginning of 2000.

Contribución INIDEP 2472
Jurquiza, Verónica; Haim, María Sol; Moroni, Mirian; Viñas, María Rosa; Poklépovich, Tomás J.; Campos, Josefina. (2025).

Primer reporte de detección y caracterización molecular de Vibrio mimicus en el Río de la Plata por secuenciación de genoma completo. Frente Marítimo 27:26-31

Abstract
Vibrio mimicus is an aquatic environment autochthonous microorganism considered, at present, as an emergent pathogen. It may be isolated from human cases of gastroenteritis, wound infections, bacteremia and otitis. It may also be associated with aquatic animal diseases. Although it was described initially as an atypical nonpathogenic species of Vibrio cholerae to which is closely related, it is now recognized as a different species. One of the objectives included in the multidisciplinary survey plan of research cruise VA12/19 was the study of potentially pathogenic species of the genus Vibrio. During the survey, surface water samples were collected at twelve stations distributed along three transects, located from the coast to the continental slope. In sampling station 4 of the central transect that includes some stations in the Rio de la Plata, V. mimicus was detected with biochemical tests and by the MALDI-TOF technology. To fully characterize and confirm the identification of the isolate, genomic DNA was sequenced using Illumina NovaSeq 6000 platform (2x150pb). The identification of V. mimicus was confirmed. Virulence and antibiotic resistance (SST6, csqA, luxS, varG) genes were detected. Conversely, plasmid replicons in the genome were not detected. Taking into consideration that this microorganism is recognized as causal agent of human and animal diseases, our results point out the need to continue studies on its evolution and biology and strengthen the knowledge on the identification of virulence and antibiotic resistance factors that may affect the pathogenic potential of this bacteria.

Contribución INIDEP 2473
Ruiz, M. Guillermina; Silva, Ricardo I.; Martínez, Ana; Montoya, Nora G. (2025).

Relaciones pigmento:clorofila A determinadas por chemtax a partir de muestras naturales de floraciones algales de la región norte de la Plataforma Continental Argentina. Frente Marítimo 27:32-46

Abstract
Toxic algal blooms may affect fishery resources, marine environment and public health. An approach to study the composition of phytoplankton communities and determine whether a bloom is potentially toxic uses pigment based chemotaxonomy, supplementing high pressure liquid chromatography (HPLC) with a factor analysis program known as CHEMTAX. To this end, it is necessary to determine first, the phytoplankton pigment concentration (chemichal markers), and, at the same time have good estimates of the values of pigment concentration: chlorophyl a (Chl. a) rates, for the different groups of algae, known as Phytoplankton Pigment Types (PhPiTs), occurring in each region of interest. Ideally this rates should be determined using monospecific cell cultures of local species (that may be difficult to obtain) or as an alternative, from nature collected samples of monospecific algal blooms; as a last resource, data from the bibliography could be used. The main objective of this study was to obtain the best possible estimation of pigment concentration: Chl. a rates in several PPTs from samples collected in the northern region of the continental shelf off Argentina. We specifically tested the hypothesis that the factor analysis of the CHEMTAX program applied to a set of samples of monospecific algal bloom pigments, could be a useful tool to estimate values of pigment rates. The hypothesis was successfully verified. The program estimated the rates of 11 different PhPiTs. The application of the results of this study is discussed. They may become a valuable input for future algal bloom studies using chemotaxonomy and CHEMTAX in the region.

Contribución INIDEP 2441
The Argentine deep sea: a new strategic frontier for sustainable development.

Bravo, M. E., Levin, L. A. ., Alder, V., Bozzano, G. ., Buren, A. D., Carbajal, J. C., Davila, P., Doti, B. L., Esteban, F. D., Flombaum, P., Giberto, D. A., Giménez, J. ., Giorgini, M., Guinder, V. A., Ibarbalz, F. M., Kahl, L. C., Lattuca, M. E., Lauretta, D., Lovrich, G. A., … Wei, C. L. (2025).

The Argentine deep sea: a new strategic frontier for sustainable development. Marine and Fishery Sciences, 38(4)
https://doi.org/10.47193/mafis.3842025011006

Abstract
The deep-sea ecosystems and biodiversity of Argentina are sensitive to the effects of climate variation such as warming, oxygen loss, and ocean acidification. This vulnerability is due to specific characteristics such as the presence of long-lived species, which can live for over 4,000 years, with very slow growth and reproduction rates, which depend on habitats with complex configurations. As a result, many deep-sea ecosystems affected by disturbances have a low probability of recovery, and if recovery occurs, it may take hundreds or even thousands of years. This document synthesizes the results of a Specialist Workshop that reviewed the current state of scientific knowledge and discussed its application to the management of Argentina’s deep sea, from an ecosystem-based perspective that considers climate variability. Argentina’s deep sea, spans depths ranging from 200 to 6,000 m, covering more than 70% of the national maritime territory, with an approximate area of 4.6 million km2. In the Argentine seabed, geomorphological and oceanographic complexity indicates a high potential to support extensive benthic biodiversity. However, knowledge about its ecosystems and the environmental management policies for this vast Argentine territory have been limited and fragmented, particularly regarding the incorporation of climate-related variables. Designing effective policies to protect its biodiversity and the multiple benefits these ecosystems provide to society implies robust technical advice, for which it is essential to strengthen scientific knowledge on Argentina’s deep-sea ecosystems and their interaction with climate variability, as well as sustained coordination and collaboration among all relevant sectors.

Contribución INIDEP 2365
Predatory impact on ichthyoplankton by Mnemiopsis leidyi (Ctenophora) is size-dependent: an experimental approach

Sobrero, L.; Puente Tapia, F.A.; Chiaverano, L.M.; Macchi, G.J.; Schiariti, A. (2025).

Predatory impact on ichthyoplankton by Mnemiopsis leidyi (Ctenophora) is size-dependent: an experimental approach. Marine Ecology Progress Series, 758, 195-201

DOI

Abstract
Understanding the size-related predatory effects of Mnemiopsis leidyi on ichthyoplankton is crucial for evaluating its effects on fish populations. This study examines the capability of M. leidyi to consume ichthyoplankton and assesses whether consumption of fish eggs is dependent on ctenophore size. Laboratory experiments indicated that M. leidyi (4.6-10.5 cm total length) ingest fish eggs and larvae of Seriola lalandi. Ingested fish larvae were fully digested, while eggs were often regurgitated undigested; however, most regurgitated eggs were non-viable. Our results also revealed a significant positive relationship between ctenophore size and egg ingestion. These findings suggest that M. leidyi can consume ichthyoplankton. However, the predatory impact that this ctenophore could exert on fish recruitment in areas where these taxa co-occur will most likely depend on ctenophore abundance and body size.

Contribución INIDEP 2367
Seasonal variability of phytoplankton community structure in a coastal station of the Argentine continental shelf based on a chemotaxonomic approach.

Ruiz, M.G.; Mattera Coy, M.B.; Carignan, M.C.; Albornoz, M.; Molinari, G.N.; Montoya, N.G. (2025). Seasonal variability of phytoplankton community structure in a coastal station of the Argentine continental shelf based on a chemotaxonomic approach. Marine and Fishery Sciences, 38(1). https://doi.org/10.47193/mafis.3812025010105

Abstract
The composition, abundance and size structure of the phytoplankton community at a coastal time series station (38° 28' S-57° 41' W, EPEA, Argentina) was characterized by applying the chemotaxonomic approach. The seasonal variability of pigment diversity determined by high-performance liquid chromatography (HPLC, n = 171), nutrient concentration (n = 934), and temperature, salinity and degree of stratification of the water column was identified (n = 190 CTD profiles). The CHEMTAX program was used to estimate phytoplankton abundance in terms of contribution to chlorophyll a concentration of the different phytoplankton pigmentary types (PPTs). Two different pigment indices were compared to estimate phytoplankton community size fractions throughout the year, giving contrasting results. Water column was mostly mixed, with minimum temperatures between July and September and maximum between January-March (range: 8-23 °C). Nitrate was the limiting nutrient, with minimal concentrations at the end of summer. It’s range varied between 0.010-13.330 μM, while silicate ranged between 0.016-10.670 μM without major seasonal variations, and phosphate between 0.120-2.180 μM. Fucoxanthin, chlorophyll c2, 19’-hexanoyl-oxy-fucoxanthin, diadinoxanthin, chlorophyll b, chlorophyll c3, peridinin and, alloxanthin, were the most frequent phytoplankton pigments. The PPT DINO-1 (dinoflagellates with peridinin), haptophytes types: HAPTO-6, HAPTO-7 and HAPTO-P showed a seasonal cycle with peaks of abundance in autumn and spring, while the diatoms DIATO-1 was high during the whole year and DIATO-2 mainly during winter. A pigment profile of a group of prymnesiophytes possessing MVChl_c3 was described. It was evident that at this site PPTs having potentially toxic species bloom under different hydrological conditions. DINO-1 is likely to bloom in April (autumn), with temperatures close to 18 °C and weak stratification conditions, while October bloom (spring) occurs with lower temperatures of 10-12 °C. DINO-4 was noted during January and February (summer), when temperature was > 18 °C, salinity < 33.7, and the water column showed maximum stratification. In contrast, the maximum abundances of DIATO-2 occurred between August and September (winter), under completely mixed conditions, high nitrate concentration and low temperature of 10 °C. This work constitutes the first description of the variability of the abundance of the main PPTs in a coastal a time series station in the southwestern Atlantic Ocean shelf throughout the annual cycle, demonstrating the power of chemotaxonomy and CHEMTAX to perform descriptive analysis of a large number of samples.

Contribución INIDEP 2375
Registros de varamientos de mamíferos marinos en la Provincia de Buenos Aires, 2010-2022: implicancias para la gestión, conservación e investigación.

Rosenthal A.F.; Seco Pon, J.P.; González Carman, V.; Denuncio, P. (2025).

**Registros de varamientos de mamíferos marinos en la Provincia de Buenos Aires, 2010-2022: implicancias para la gestión, conservación e investigación. Mastozoología Neotropical, 32(1). **
https://doi.org/10.31687/saremMN.25.32.01.02.e1075

Abstract
El monitoreo de mamíferos marinos a través del registro de varamientos es un método de bajo costo que permite conocer la diversidad de especies y tener una aproximación del tamaño de sus poblaciones. Si ese monitoreo se mantiene en el tiempo, resulta una valiosa herramienta para determinar y evaluar cambios en un ecosistema dado. En este estudio se presenta un análisis preliminar de los varamientos de mamíferos marinos registrados en playas de la provincia de Buenos Aires, Argentina, entre los años 2010 y 2022, con el objetivo de evaluar su diversidad especíca en la región, abundancia, frecuencia y variaciones inter e intra-anuales. Los resultados demostraron que el ensamble de mamíferos marinos estuvo compuesto por 15 especies, de ellas, Arctocephalus australis, Pontoporia blainvillei y Otaria avescens fueron las más importantes en orden descendente. De las especies halladas, 11 habitan ambientes tanto neríticos como oceánicos, mientras que el resto de las especies son exclusivamente neríticas u oceánicas. La mayor tasa de varamientos fue de 0,13 ejemplares/km en 2015, mientras que la menor fue de 0,04 en 2021 y 2022. Los análisis estadísticos realizados demostraron una fuerte in uencia de las estaciones del año (variación intra-anual) en el número total de animales varados y en las dos especies más numerosas (A. australis y P. blainvillei). Ante el incremento de las actividades antropogénicas en la plataforma argentina adyacente (p. ej., exploración y explotación de hidrocarburos), este estudio constituye una importante línea de base que re eja la diversidad y tasa de varamientos de las especies de mamíferos marinos en las costas del norte de la Argentina.

Contribución INIDEP 2396
Spring copepod functional diversity associated with the oceanographic fronts of the Southwestern Atlantic Ocean.

Cepeda, G.D.; Becker, É.C.; Derisio, C.; Severo, A.; Acha, E.M. (2025). Spring copepod functional diversity associated with the oceanographic fronts of the Southwestern Atlantic Ocean. Progress in Oceanography, 232, 103421. https://doi.org/10.1016/j.pocean.2025.103421

Abstract
Studies on species’ functional traits are increasingly used to explore the links between zooplankton community structure and ecosystem functioning. This study investigates copepod diversity across the main frontal types along the continental shelf and shelf break of eastern South America (32°S-55°S), using taxonomic and functional diversity approaches. We analyzed 53 copepod species grouped by five key traits, comparing adult copepod diversity, functional traits, diversity indices, and functional space between frontal systems and surrounding control regions. Contrary to expectations, no significant differences in functional or taxonomic diversity were observed between frontal systems and control regions. Instead, a distinct latitudinal pattern in functional group distribution emerged, shaped by reproductive mode, myelination, feeding traits, and body size. This pattern revealed a decline in species richness, taxonomic diversity, functional richness, and functional space toward southern regions. The findings suggest spatial filtering of specific trait combinations: larger and medium-sized broadcasters and herbivore-omnivore current feeders dominate colder southern systems, while warmer northern systems support a broader array of functional groups, including small-sized sac-spawners, omnivores-detritivores, carnivores, ambush feeders, and cruise feeders. The transition from heterogeneous northern waters—populated by species from the Malvinas Current, subtropical, and subantarctic shelf waters—to colder, less heterogeneous subantarctic waters in the south likely accounts for the greater functional diversity in northern latitudes. These results underscore the role of environmental heterogeneity, species interactions, and ecosystem functioning in shaping copepod communities along the eastern South American continental shelf.

Contribución INIDEP 2397
New northernmost record of Clathria (Clathria) unica and updated records of Cliona aff. celata and Spongia (Spongia) magellanica in Mar del Plata, Argentina, SW Atlantic Ocean.

Pavón Novarín, M.; Meretta, P.; Genzano, G.; Schejter, L. (2025). New northernmost record of Clathria (Clathria) unica and updated records of Cliona aff. celata and Spongia (Spongia) magellanica in Mar del Plata, Argentina, SW Atlantic Ocean. Journal of the Marine Biological Association of United Kingdom, 105. https://doi.org/10.1017/S0025315425000219

Abstract
In this study the finding of the sponge Clathria (Clathria) unica in coastal waters of Mar del Plata city (38°14′24″S, 57°27′30″W), Argentina, at the formation called ‘Banco de Afuera’, is reported. This record constitutes the northernmost record of the species, which was known until the present study only from its type locality in San Antonio Oeste, Río Negro province. Additionally, the bathymetric range of the species is updated from intertidal to 20 m. Other two common sponge species, Cliona aff. celata and Spongia (Spongia) magellanica, were also recorded in this environment for the first time.

Contribución INIDEP 2398
Revisiting Asbestopluma (Asbestopluma) magnifica in the SW Atlantic: taxonomic amendments, new insights, and evidence for potential conspecificity with Asbestopluma (Asbestopluma) sarsensis.

Pavón Novarín, M.; Fernández, J.C.C.; Hajdu, E.; Schejter, L. (2025). Revisiting Asbestopluma (Asbestopluma) magnifica in the SW Atlantic: taxonomic amendments, new insights, and evidence for potential conspecificity with Asbestopluma (Asbestopluma) sarsensis. Journal of the Marine Biological Association of United Kingdom, 105, e20. https://doi.org/10.1017/S0025315425000116

Abstract
In the present study we update the distributional, bathymetric ranges and taxonomic characters of the carnivorous sponge Asbestopluma (Asbestopluma) magnifica Lopez, Bravo & Hajdu, 2011 providing new records for Argentinian jurisdictional waters in the SW Atlantic Ocean, including the Marine Protected Area Namuncurá/Burdwood Bank. The shallowest bathymetric range is now changed to the upper bathyal (289 m depth). We also amend the original description after re-examination of type materials, when markedly different micrometric values were observed for their subtylostyles and acanthotylostrongyles. We noticed a remarkable similarity between Asbestopluma (Asbestopluma) sarsensis Goodwin, Berman, Downey & Hendry, 2017 and A. (A.) magnifica and we suspect they may be synonymous, but we refrain from taking a formal decision pending revision of all materials reported for the younger taxon or a genetic analysis.

Contribución INIDEP 2399
Parasite diversity in sea turtles of the temperate SW Atlantic: a bridge between systematics and ecology.
Palumbo, E.; Álvarez C.K.; Rodriguez-Heredia, S.; Rosenthal, A.; Vassallo, M.; Bruno, I.M.; Loureiro, J.; Diaz, L.; Faiella, A.; Werneck, M.R.; Diaz, J.L.; González Carman, V. (2025). Parasite diversity in sea turtles of the temperate SW Atlantic: a bridge between systematics and ecology. Marine Biology, 172. https://doi.org/10.1007/s00227-025-04610-x

Abstract
Parasite studies can provide insights into important aspects of host ecology, which can be particularly important for species of conservation concern. This research focused on the parasite diversity of two sea turtle species —the loggerhead Caretta caretta and the leatherback Dermochelys coriacea— in the temperate South West Atlantic, a region and species relatively understudied. Over a 15-year period (2008–2023), 30 sea turtles were sampled from the northern coast of Argentina. Through morphological and molecular tools, we identified five parasite species (the digeneans Pyelosomum renicapite and Pleurogonius longiusculus, the nematodes Kathlania leptura and Sulcascaris sulcata and the leech Ozobranchus margoi) in loggerheads and two digeneans (P. renicapite and Orchidasma amphiorchis) in leatherbacks. All the species constitute the first report of the parasite in Argentina, and O. amphiorchis represents a new host-parasite association for leatherbacks. Comparative biogeographic analysis using the Regional Management Unit (RMU) framework suggested that parasites could reveal connectivity between RMUs, although there are several information gaps. An increasing number of parasite studies can help understand sea turtle feeding ecology, ontogenetic shifts and health status and thus enhance conservation strategies for sea turtles globally.

Contribución INIDEP 2407
Monitoring plastic pollution using bioindicators: a global review and recommendations for marine environments.

Savoca, M.S.; Abreo, N.A.; Arias, A.H.; Baes, L.; Baini, M.; Bergami, E.; Brander, S.; Canals, M.; Choy, C.A.; Corsi, I.; De Witte, B.; Domit, C.; Dudas, S.; Duncan, E.M.; Fernández, C.E.; Fossi, M.C.; Garcés-Ordóñez, O.; Godley, B.J.; González-Paredes, D.; González Carman, V.; Hamilton, B.M.; Hardesty, B.D.; Hong, S.H.; Kahane-Rapport, S.; Kashiwabara, L.M.; Lacerda, M. B.; Luna-Jorquera, G.; Manno, C.; Nelms, S.E.; Panti, C.; Pérez-Venegas, D.J.; Pham, C.K.; Provencher, J.F.; Purca, S.; Rashid, H.; Rodríguez, Y.; Sparks, C.; Sun, C.; Thiel, M.; Tsangaris, C.; Santos, R.G. (2025). Monitoring plastic pollution using bioindicators: a global review and recommendations for marine environments. Environmental Science: Advances, 4(1). https://doi.org/10.1039/D4VA00174E

Abstract
Monitoring the movement of plastic into marine food webs is central to understanding and mitigating the plastic pollution crisis. Bioindicators have been a component of the environmental monitoring toolkit for decades, but how, where, and which bioindicators are used in long-term monitoring programs has not yet been assessed. Moreover, these programs have yet to be synthesized and evaluated globally. Doing so is imperative if we are to learn from these pioneering programs and expand on their efforts. We reviewed global monitoring programs using bioindicators that focus on plastic pollution and found 11 worldwide that met our definition of long-term monitoring. Limited data availability and few programs in the Global South hinder progress on tracking global trends. Most commonly, long-term programs either tracked macroplastics with opportunistic sampling of large vertebrates or monitored microplastics with targeted sampling of invertebrates. These long-term bioindicators could be incorporated as essential ocean variables in the global ocean observing system, and thus provide critical insights into the trajectory and effects of plastic pollution on marine ecosystems. However, to enhance the effectiveness and inclusivity of these monitoring efforts, there is a pressing need for the implementation of harmonized and standardized methods, increased collaboration between regions, and greater support for data sharing and open science practices. By addressing these challenges and expanding the geographic scope of monitoring programs, we can better inform evidence-based policies and interventions aimed at mitigating plastic pollution on a global scale.

Contribución INIDEP 2420
Ecological role of pelagic appendicularians in sub-Antarctic coastal and oceanic waters of the Southwest Atlantic Ocean.

Alves, N.M.; Spinelli, M.L.; Martín, J.; Malits, A.; Capitanio, F.L. (2025). Ecological role of pelagic appendicularians in sub-Antarctic coastal and oceanic waters of the Southwest Atlantic Ocean. Polar Biology, 48, 28. https://doi.org/10.1007/s00300-024-03331-z

Abstract
Appendicularians are recognized as a prominent mesozooplankton group in pelagic environments due to their abundance and their crucial role in food webs, as they bridge the gap between primary producers and higher trophic levels. Samples were collected during three spring oceanographic surveys conducted in 2014, 2015, and 2016, in the coastal area near Staten Island (SI) and the open sea Marine Protected Area Namuncurá-Burdwood Bank (BB). Surface currents and water properties suggest that BB is relatively isolated from the adjacent regions. We conducted a comparative analysis of density, biomass, and maturity stages of two appendicularians species, Oikopleura fusiformis and Fritillaria borealis, in these two areas with contrasting environmental characteristics. O. fusiformis dominated in both areas, while F. borealis was recorded mainly in the coastal. Higher densities of O. fusiformis were associated with higher chlorophyll-a concentrations in SI, as well as with higher density of pico-nanoplankton in the BB area. No correlation was found between the presence of appendicularians and environmental variables, such as temperature and salinity. However, in coastal areas with higher temperatures, smaller size classes were observed. Occasional occurrences of F. borealis on the BB are tentatively related to intrusions of offshore waters into the bank’s plateau. Nano-picoeukaryotes and bacteria were more abundant in the oligotrophic open sea BB, which could explain the high abundance of appendicularians there. Baseline data of these species in protected areas and surrounding areas are crucial to inform stakeholders and guide responses to future regional and global environmental changes.

Contribución INIDEP 2422
Linking copepod functional traits to diel vertical migration at the Patagonian shelf-break.

Severo, A.; Acha, E. M.; Cepeda, G.D. (2025). Linking copepod functional traits to diel vertical migration at the Patagonian shelf-break. Marine Biology, 172. https://doi.org/10.1007/s00227-025-04624-5

Abstract
Copepod diel vertical migration (DVM) is a significant phenomenon with implications for the biological pump and pelagic food webs; nevertheless, its drivers and ecological significance are not fully understood. This study analyzed the daytime and nighttime vertical density of females, males, and developmental stages of copepods to investigate the role of functional traits, such as spawning strategy, body size, trophic group, and feeding mode, in DVM at the Patagonian shelf-break (44ºS–47ºS and 60ºW–61ºW). Only females and late copepodites exhibited a normal DVM at oceanic stations, showing their weighted mean depth (WMD) near the surface during the nighttime and at greater depths during the daytime. Fourteen dominant species (the most densely and frequently) were identified based on a relative importance index (RII). Females that are sac-spawners, detritivores, carnivores, omnivores, and/or cruise-feeders exhibited normal DVM, such as Clausocalanus brevipes, Oithona atlantica, Ctenocalanus vanus, Clausocalanus laticeps, Scolecithricella minor, Aetideus armatus, Haloptilus oxycephalus, Metridia lucens, and Candacia longimana, presenting their WMD near the surface and at the fluorescence maxima at nighttime, and below the thermocline at daytime. Conversely, females that are broadcasters, large-sized, herbivores, and/or current-feeders did not exhibit consistent DVM patterns, such as Calanus simillimus, Rhincalanus gigas, and Subeucalanus longiceps, presenting their WMD above the thermocline and at the fluorescence maxima during both daytime and nighttime. Copepod depth selection appears to be influenced by a combination of morphological, physiological, behavioral, and life history traits, that, in each case, would optimize predator avoidance, foraging, and reproduction opportunities.

Contribución INIDEP 2425
Massive arrivals of egg capsules of the gastropod Pachycymbiola brasiliana and the hydroid Amphisbetia operculata in the beaches of the Southwestern Atlantic Ocean.

Schejter, L.; Genzano, G.N.; Gûller, M.; Maenza, R.A.; Zelaya, D.G. (2025). Massive arrivals of egg capsules of the gastropod Pachycymbiola brasiliana and the hydroid Amphisbetia operculata in the beaches of the Southwestern Atlantic Ocean. Regional Studies in Marine Science, 84. https://doi.org/10.1016/j.rsma.2025.104117

Abstract
The phenomenon of subtidal organisms arriving, accumulating, and depositing onto the beach is not unusual, although they have been seldom documented in South America, especially regarding marine invertebrates. In this study twelve major events that happened at the Atlantic South American shorelines between 35° and 38°S during the austral summer of 2022–2023 were investigated. The arrivals were mainly composed by egg capsules of the gastropod Pachycymbiola brasiliana and by colonies of the hydroid Amphisbetia operculata. Prior to these events, persistent winds from the north/northeast quadrant that promoted moderate to strong currents toward the coastline were recorded. The compilation of other historic events reveals that the 2022–2023 are probably the largest and best documented events involving these species. Great mortality of recruits of the gastropod Pachycymbiola brasiliana may have consequences for the species as well as other members of the local assemblages and food webs. Contrarily, to established populations of the hydroid Amphisbetia operculata, these events pose minimal biological or ecological threats. Unpleasant subsequent conditions for tourists at the beaches are caused by the wrack. This contribution also draws attention to the lack of legislation in Argentina regarding how this wrack should be removed from the beaches.

Contribución INIDEP 2428
Ichthyoplankton temporal and spatial patterns in sub-Antarctic coastal and oceanic waters of the Southwestern Atlantic.

Bruno, D.O.; Riccialdelli, L.; Becker, Y.; Martin, J.; Victorio, M.F.; Acha, E.M.; Fernández, D.A. (2025). Ichthyoplankton temporal and spatial patterns in sub-Antarctic coastal and oceanic waters of the Southwestern Atlantic. Estuarine, Coastal and Shelf Science, 318, 109260.
https://doi.org/10.1016/j.ecss.2025.109260

Abstract
The southernmost region of the Southwestern Atlantic (SW Atlantic) has a complex environmental structure with different oceanographic conditions that aid the survival of early life stages of sub-Antarctic fish. This study evaluated the spatial and temporal variations in ichthyoplankton composition of SW Atlantic's sub-Antarctic coastal and oceanic waters and the relationship with environmental variables (water temperature and salinity). Six multidisciplinary oceanographic surveys (austral spring of 2014, 2015, 2016, summer of 2015, and autumn of 2016, 2017) were conducted in two coastal and three oceanic zones of the southern SW Atlantic. A total of 425 fish eggs and 871 fish larvae at the yolk sac (N = 37), preflexion (N = 513), flexion (N = 13), and postflexion (N = 308) stages were collected. Eleven fish taxa in the larval stage were identified. The highest abundance of eggs and larvae in the preflexion stage occurred in spring, dominated by the Fuegian sprat (Sprattus fuegensis) in all zones. However, the abundance of fish larvae in the postflexion stage was higher in autumn at the southern slope of the Burdwood Bank, with a dominance of Patagonian cods (Patagonotothen spp.). Water temperature played a significant role in explaining the abundance of larvae in the preflexion stage, whereas water salinity was significant for eggs and larvae in the postflexion stage. Our results allow us to infer the role of this complex oceanographic system in the early life history of fish. Thus, a conceptual framework for the ichthyoplankton distribution patterns in the area is proposed.