Southwestern Atlantic Research Articles

Definition of no‐fishing zones and fishing effort limits to reduce franciscana bycatch to sustainable levels in southern Brazil

AbstractFranciscana dolphin Pontoporia blainvillei bycatch has been high for near six decades in western South Atlantic, with large regional variation. In 2012, the Brazilian Government‐regulated gillnet fisheries in south and southeast Brazil by reducing fishing effort and establishing no‐fishing zones. However, there is evidence that the magnitude of franciscana bycatch remains high and unsustainable. The aims of this study were to identify hotspot areas of franciscana bycatch associated with two main gillnet fisheries and to propose no‐fishing zones combined with limited total allowable fishing effort (i.e. total net length per season) in order to meet management objectives in southern Brazil. A hierarchical Bayesian model using integrated nested Laplace approximation (INLA) was employed based on 1427 reported settings from 1999 to 2003 and 2006 to 2009. Hotspot zones were detected and are proposed as no‐fishing zone during the white croaker Micropogonias furnieri and striped weakfish Cynoscion guatucupa gillnet fishing seasons. Their extents represent 6% (1466.8 km2) and 19% (4493.7 km2) of the fishing ground (23 204.1 km2) during croaker and weakfish fishing seasons respectively. The total allowable fishing effort estimated outside the no‐fishing zones were estimated at 541 km (95% credible interval (CrI) [339; 940]) during croaker and 688 km (CrI [312; 2,166]) during weakfish fishing seasons, one order of magnitude lower than the current total fishing effort. The drastic reduction of total fishing effort estimated in this study is largely due to weak protection measures since the gillnet fisheries became the major conservation concern for franciscana by the end of 1970s in southern Brazil. Although the implementation of the proposed exclusion zones and limiting fishing effort will strongly impact the status quo, they were based on the best scientific evidence and on a clearly defined management goal to reduce the risk of the franciscana population’s collapse in southern Brazil.

Revision of the deep-sea Eulimidae (Gastropoda, Caenogastropoda) from off Northeast Brazil.

The present study reviews the taxonomy of the marine gastropods belonging to the family Eulimidae Philippi, 1853 from the continental slope off Northeast Brazil. The genera Abyssoaclis Barros, Mello, Barros, Lima, Santos, Cabral Padovan, 2003 and Aclis Lovén, 1846 were not treated here. A total of 20 taxa were identified in this region, excluding Eulima hebes Watson, 1883, a species with a doubtful classification in Eulimidae. The species were assigned to the following genera: Costaclis Bartsch, 1947, Eulima Risso, 1826, Fusceulima Laseron, 1955, Melanella Bowdich, 1822, Ophieulima Warén Sibuet, 1981, Sticteulima Laseron, 1955, Thaleia Warén, 1979, and Umbilibalcis Bouchet Warén, 1986. The genera Sticteulima, Ophieulima and Umbilibalcis are reported for the first time in the southwestern Atlantic. Four species represent new records for the southwestern Atlantic. A redescription of the shell morphology is provided for: Costaclis egregia (Dall, 1889b), Melanella doederleini (Brusina, 1886), and Umbilibalcis lata (Dall, 1889b). Additional information to the original description are reported for other species. Melanella sarissa is considered as a synonym of Melanella cinca Dall, 1927. Six new species are described: Eulima cracentis sp. nov., Melanella paraabida sp. nov., M. adiastalta sp. nov., M. anapetes sp. nov., Sticteulima cabrali sp. nov. and S. canopusensis sp. nov. Lectotypes are designated for: Costaclis hyalina, C. egregia, Eulima ephamilla (Watson, 1883), E. psila and E. (?) hebes. Eulima sp. 1, Melanella sp. 1 and Melanella sp. 2 are potential new species, but the scarcity of material precludes a formal description at this moment.

Long-term and multilevel impact assessment of the 2015–2016 El Niño on a sandy beach of the southwestern Atlantic

As a land-sea interface, the fingerprints of climate perturbations may be immediately and profoundly felt in sandy beaches and the macroinvertebrates they harbour. In particular, extreme climatological events can result in long-lasting or irreversible ecological changes, and therefore, it has become critical to understand how these ecosystems respond to strong pulse perturbations. This study assessed the main impacts prompted by the 2015–2016 El Niño on a Southwestern Atlantic sandy beach ecosystem. A long-term (1982–2019) analysis was carried out, attending historical climate components and multilevel indicators of change across levels of ecological organization. The trophic networks of four ecosystem states were compared, and the macroinvertebrate community structure was analysed in terms of species richness, abundance and biomass and deconstructed by taxonomy, beach zone occupied, feeding, and development modes. The potential recovery pathway of the system was also assessed. Climatic effects were reflected in a marked increase in sea surface temperature anomalies, rainfall, and in the discharge of the widest estuary of the world (Río de la Plata). An abrupt disruption of ecological attributes due to El Niño effects was evidenced. After the event, the ecosystem shifted to a higher organization of the flow structure (Ascendency), a lower adaptive potential (Overhead), and a marked increase in efficiency (Robustness), reflecting a more vulnerable state to absorb disturbances. The decrease in species abundance and biomass was particularly noticeable in molluscs, filter feeders, and low intertidal/subtidal groups. By contrast, polychaetes/deposit feeders were favoured, triggering a transitional community state dominated by opportunistic species. The results highlight how extreme climatic events could prevent the recovery of a sandy beach ecosystem, as pulses may induce lag and legacy effects.

Planktonic foraminifera assemblages from the Brazil–Malvinas Confluence: palaeoceanographic implications of sub-surface temperature reconstructions in the western South Atlantic

Planktonic foraminifera census data have been widely used to reconstruct changes in ocean ecosystems as well as ocean chemistry and circulation through calibration functions. Here we analyse new core-top census data from 22 sites in the western South Atlantic, improving the geographical coverage and spatial resolution of the environmental gradients from the region covered by the Brazil–Malvinas Confluence (˜38°S–53°W). We combine them with previous data to provide an up-to-date compilation of the western South Atlantic planktonic foraminifera–calibration data set. We study the relationship between the assemblages present in the core-top samples and the most dynamic environmental variables from the region to establish the environmental variable(s) more resolved by the assemblages. Therefore, we develop and assess a new calibration function using the data set and testing several statistical models at different water depths. Our results reveal that the distribution and abundance of the species in the Brazil–Malvinas Confluence region mainly reflect the influence of two environmental variables: the mixed layer temperature and mixed layer depth (57% of total variance). The most precise reconstructions were obtained when using sub-surface temperatures between 40 and 50 m water depth. The application of the calibration function to a Holocene sediment core at ˜37°S–53°W revealed mean annual sub-surface temperature reconstructions between 8°C and 11°C, confirming the northward displacement of the Brazil–Malvinas Confluence during the onset of the Holocene and suggesting a major influence of the Malvinas Current during the entire Holocene at the studied site.

Biological aspects of Mugil liza Valenciennes, 1836 in a tropical estuarine bay in the southwestern Atlantic

Evaluation of population parameters of Mugil liza caught at Guanabara Bay was conducted using size frequency and biological data. Total length ranged between 22.0 and 81.5 cm. The spawning season occurred between March and August. The size of the first maturity was estimated as 49.8 cm. The estimated growth parameters were L∞= 82.31 cm and K = 0.30 y −1. Instantaneous rate of total and natural mortalities were estimated as 1.02 and 0.56 y −1. The fishing mortality (F = 0.46 y −1) was greater than the optimum (Fopt= 0.28 y −1) and the limit of biological reference point (Flimit= 0.37 y −1). The exploitation rate (E=0.45) was higher than the E0.5= 0.33, suggesting that decreasing the current fishing effort could reduce exploitation within sustainable limits.

Reproductive biology and recruitment of bluefish Pomatomus saltatrix (Perciformes: Pomatomidae) in the southwestern Atlantic

The bluefish, Pomatomus saltatrix (Linneus 1766) is captured by industrial, artisanal, and recreational fisheries throughout its distribution range. The reproductive biology of P. saltatrix in the southwestern Atlantic was studied using 1,102 specimens captured by the Brazilian commercial fleet between March 2014 and December 2015. The recruitment period was identified from records of juveniles in experimental beach seine hauls carried out on sandy beaches in the external sector of Guanabara Bay for four years (2012–2015). Based on the reproductive indices and on the macro- and microscopic analyses of the gonads, spawning peaks were identified in autumn and spring. The size at first maturity was estimated at 35.5, 38.3, and 37.4 cm for females, males, and general, respectively. Ovary analyses and measurements of the oocyte diameters indicated that bluefish are multiple spawners with asynchronous oocyte development. The batch fecundity estimate was 202,752.5 eggs and ranged from 9,800.9 to 426,787.0 eggs. The species reproduces throughout the entire study area, but it is more active in the south of Arraial do Cabo. The young-of-the-year were recorded on shallow water in all seasons, with modal peaks in the summer months. The parameters estimated in this study expand and update information on this species, providing important data for the evaluation and fisheries management of the stock of P. saltatrix in the southwestern Atlantic.

Delphinid Mixed-Species Associations in the Oceanic Waters of the Western South Atlantic

Delphinid Mixed-Species Associations in the Oceanic Waters of the Western South Atlantic

OSTEOLOGY OF PARABROTULA PLAGIOPHTHALMUS (OPHIDIIFORMES: BYTHITOIDEI: BYTHITIDAE)

Parabrotula (Zugmayer 1911a), included in the family Bythitidae (Ophidiiformes), is a genus of small viviparous mesopelagic fishes with two valid species. Parabrotula plagiophthalmus is known from collections made worldwide except in the eastern Indian, eastern Pacific, and western South Atlantic Oceans; most specimens are from the North Atlantic Ocean. Most anatomical data for P. plagiophthalmus are limited to aspects of external anatomy, the reproductive system, and meristic data that can be gathered through radiographs; virtually no data on other aspects of the osteology of P. plagiophthalmus are available. In this study, we describe the skeleton of P. plagiophthalmus from cleared and stained specimens and computed tomography data. Many aspects of the skeleton of P. plagiophthalmus are reduced (subopercle; ceratobranchial 5; gill rakers; gill filaments; distal radials of median pterygiophores; caudal skeleton; posttemporal; supracleithrum; scapula; distal pectoral radials; pelvic girdle and fins; scales) or absent (mesethmoid; nasal; pterosphenoid; intercalar; infraorbital bones; endopterygoid; coronomeckelian; supramaxilla; pharyngeal toothplates). All bones of the skull are extremely thin dermal or perichondral ossifications, with little to no endochondral components. The vomer supports a variable number of teeth (0–3). The pars autopalatina and its ossification are separated from the pars metapterygoidea and pars quadrata and their ossifications; the thin ectopterygoid bridges these elements of the suspensorium. The lower jaw is very large compared with all other elements of the viscerocranium. The pectoral radial plate was never observed to be divided into separate radial elements. We discuss the skeleton of Parabrotula in the context of other taxa but call attention to the need for further comparative studies of the anatomy of ophidiiform fishes.

Iba: The First Pure Tropical Cyclogenesis Over the Western South Atlantic Ocean

AbstractIn March 2019, the tropical western South Atlantic Ocean (∼16.5°S) registered the first pure tropical cyclogenesis since the beginning of the satellite era, which the Brazilian Navy named Iba. This study presents a description of the synoptic features and meteorological mechanisms contributing to Iba's initial cyclonic vorticity as well as the anomalous synoptic patterns linked to this unprecedented tropical cyclogenesis. Moreover, a general description of Iba's lifecycle is provided. The genesis of Iba was as a pure tropical cyclone (00:00 UTC on March 22), and it underwent subtropical (18:00 UTC on March 25) and extratropical (06:00 UTC on March 29) transitions. Anomalies for a 5‐day period prior to the genesis relative to the March climatology show environmental features appropriate for tropical cyclogenesis: (a) vertical wind shear in the 850–200 hPa lower than 10 m s−1, (b) intense initial cyclonic relative vorticity at 925 hPa (−10 × 10−5 s−1), (c) latent and sensible heat fluxes near the climatological values (∼150 W m−2), (d) warmer sea surface temperature (+2°C), and (e) relative humidity at 700 hPa 20% higher than the climatology. These features were associated with an anomalous wave pattern at 500 hPa, resembling a blocking structure over the southeastern South Pacific Ocean, and an anticyclonic circulation at upper levels over southeastern Brazil. This environment propitiated a weak vertical wind shear and convective cloud organization. Near the surface, the horizontal wind shear between the postfrontal southwesterly winds and the northeasterly winds of the South Atlantic subtropical anticyclone helped to generate Iba's initial cyclonic vorticity.

Intraspecific variation in short-beaked common dolphin’s whistle repertoire

ABSTRACT Dolphins’ whistles are strongly diversified mainly related to physiology and behaviour. We present the whistle characteristics and intraspecific variations of short-beaked common dolphins Delphinus delphis of the Western South Atlantic Ocean (WSAO). A total of 1630 whistles from six encounters were analysed considering group size, contours and acoustical parameters. No significant correlation was found (p > 0.05) between number of whistles and the group size. Upsweep, downsweep and constant were the most frequent contours. A positive relation between the downsweep contour and group size was detected (p < 0.05). Minimum, maximum, centre, peak, initial and final frequencies, frequency range, frequency gradient, duration and inflection points were extracted. The frequencies ranged from 1.34 to 35.23 kHz and the duration varied from 0.11 to 2.16 seconds. Comparing encounters between years through Bonferroni method, minimum frequency, duration, and frequency range were significantly different. C5.0 decision tree showed that whistles of 2014 and 2015 had correct classifications (67.0% and 54.0%, respectively). The nMDS grouped the Atlantic and Pacific oceans based on inflection points and duration, further corroborated through PERMANOVA (p < 0.05). Our results suggest the influence of certain parameters related to intraspecific variation. Whistles comparison with other localities corroborates with differences in geographical scale.

Predator–prey interactions as key drivers for the invasion success of a potentially neurotoxic sea slug

Only a fraction of the species that are introduced succeed in the non-native environment, while others fail to survive, reproduce and/or disperse. Understanding the causes underlying each outcome is key to designing better early detection, prevention and management programs, and to deepen our knowledge of the invasion process. Here, we examine whether predator–prey interactions favor the invasion of a potentially neurotoxic mollusk in the South Western Atlantic (SWA). The grey side-gilled sea slug Pleurobranchaea maculata was recently detected in the SWA, where it has spread rapidly along the coast. In this work, we examine two hypotheses that may have driven the invasion success of P. maculata: (1) it has a high dietary plasticity, able to exploit resources in a variety of habitats within the invaded range and simultaneously (2) it lacks native predators that can control its abundance or spread. First, we identified the prey sources of P. maculata through experimental trials; then we compared its diet composition between different sites and seasons; and finally we experimentally assessed the effect of native potential predators. We found that diet composition is broad and varies in time and space, probably in relation to prey availability. Additionally, we observed that local predators do not recognize P. maculata as a prey. Probably, mechanisms underlying predator avoidance are related to the presence of chemical defenses that can be novel in the invaded environment. We propose that predator–prey interactions are key drivers favoring the establishment of non-native P. maculata via high levels of plasticity to exploit resources, the absence of biotic resistance and the increased availability of food associated with artificial substrates such as ports are probable mechanisms underlying the invasion success of this marine gastropod.

Drivers of damselfishes distribution patterns in the southwestern Atlantic: tropical and subtropical reefs compared

Abstract Damselfishes are known keystone species of reef environments, however large-scale distribution patterns are poorly studied in the southwestern Atlantic. We evaluated main drivers of distribution of three conspicuous damselfishes, along tropical and subtropical coastal systems, in Brazil. Abundances were assessed against wave exposure, depth (within 1–7 m in tropical and 1–11 m in subtropical reefs) and benthic cover. Despite differences between systems, exposure and depth consistently explained damselfishes distribution. Stegastes fuscus, the larger damselfish species of the genus in the southwestern Atlantic, was dominant in both systems, inhabiting preferably shallow and sheltered reefs. Conversely, Stegastes variabilis occupied shallow habitats with higher exposure. Stegastes pictus was absent from tropical reefs sampled, inhabiting depths &gt;7 m, in subtropical reefs. Species were weakly associated with benthic features, which poorly predicted changes in abundances. Regardless, S. fuscus showed association with articulated calcareous algae, and S. variabilis juveniles associated with erect macroalgae. Despite occurring in very distinctive reef systems, Brazilian damsels habitat requirements are consistent in both tropical and subtropical reefs. While highly persistent species, long term monitoring will inform us how they respond to pervasive global changes and human impacts along Brazilian reefs.

Deep-sea anglerfishes (Lophiiformes: Ceratioidei) from off northeastern Brazil, with remarks on the ceratioids reported from the Brazilian Exclusive Economic Zone

Abstract The deep-sea anglerfishes of the suborder Ceratioidei (Lophiiformes) are represented by about 170 valid species with some of the most extraordinary morphological and reproductive adaptations among vertebrates, including extreme sexual dimorphism and male parasitism. Here we report on the diversity and distribution of rare ceratioids collected during the ABRACOS (Acoustics along the BRAzilian COaSt) expeditions off northeastern Brazil and the Fernando de Noronha Ridge (Rocas Atoll, Fernando de Noronha Archipelago, and associated seamounts). Chaenophryne ramifera, Oneirodes anisacanthus, O. carlsbergi, Gigantactis watermani, and unidentified specimens of Caulophryne, Dolopichthys, and Rhynchactis are recorded for the first time in the Brazilian Exclusive Economic Zone. Ceratias uranoscopus, Melanocetus johnsonii, and Chaenophryne draco have their distributions extended in Brazilian waters. Caulophryne, O. anisacanthus, and G. watermani are also recorded for the first time in the western South Atlantic. The specimen of G. watermani reported here represents the third known specimen of the species, and variations of its escal anatomy in relation to the holotype are described. Based on specimens examined and a review of records in the literature, 20 species of the Ceratioidei, in addition to unidentified species of Caulophryne, Dolopichthys, and Rhynchactis, are confirmed in the Brazilian Exclusive Economic Zone.

Dropstones in the Mar del Plata Canyon Area (SW Atlantic): Evidence for Provenance, Transport, Distribution, and Oceanographic Implications

AbstractA variety of gravel‐ to cobble‐sized rocks, recovered from the Mar del Plata (MdP) Canyon area (Western South Atlantic at 38°S) and interpreted as ice‐rafted debris, represent the first evidence that large icebergs have floated in the Falkland (Malvinas) Current from the southern polar high latitudes far northward. Detailed petrographic analyses identified the Antarctic Peninsula, sub‐Antarctic islands in the Scotia Sea, and Tierra del Fuego as plausible source areas. The drift process could have started as early as at the beginning of the last deglaciation, according to an age obtained from a cold‐water coral fragment associated with one of the dropstones. At the end of the Last Glacial Maximum, large icebergs have been supplied to the Antarctic Circumpolar Current, captured by those ocean current branches that circumvent the Falkland (Malvinas) Islands and entered the Argentine Margin. When the iceberg fleets approached the Brazil‐Falkland (Malvinas) Confluence Zone with its steep latitudinal temperature gradient, the icebergs got oceanographically trapped and melted off rapidly. The sediment load sinking down to the seafloor formed a dropstone blanket particularly where the MdP Canyon had incised into the continental slope. Here, mass‐flow processes, induced by local slope instability, and along‐slope sediment resorting, due to the erosional effects of strong and persistent contouritic bottom currents, favored local enrichment in dropstones in the form of a loose, coarse sediment drape inside morphological depressions. The bottom current velocity would be locally strong enough to rework this sediment, leaving coarse rafted debris as a lag deposit.

A New Species of Amphipod Pariphinotus Kunkel, 1910 (Amphipoda: Phliantidae) from the Southwestern Atlantic.

The genus Pariphinotus Kunkel, 1910 comprises a total of six species around the world, with circumtropical and subtropical distribution, commonly occurring in shallow waters, in soft bottoms and algae, including a previous record of P. seclusus (Shoemaker, 1933) from Brazil. Material examined was collected by SCUBA diving, from rhodolith beds, 12 meters deep, at the Fernando de Noronha Archipelago, off the northeastern Brazilian coast. The new Brazilian species described here can be diagnosed by a unique combination of character states present in other species of the genus. However, it has two exclusive characteristics, distinguishing it from the group: medial apex of pleopod 3 peduncle with two small hook setae, and uropod 1 peduncle not exceeding the apex of telson.

Beyond genetic differences: epigenetic variation in common bottlenose dolphins Tursiops truncatus from contrasting marine ecosystems

Recent genetic and morphological studies have indicated an incipient ecological divergence between 2 ecotypes of common bottlenose dolphinTursiops truncatusin the Southwestern Atlantic. However, genetic variation is not the only molecular mechanism that alters the phenotype of these animals: epigenetics can also influence phenotypic plasticity, as well as the ecological adaptation and divergence of natural populations. Nevertheless, very little is known about the role that epigenetics plays in the population ecology of marine mammals. In this work, we tested whether there are differences in DNA methylation patterns between a coastal and an offshore ecotype of common bottlenose dolphin. Methylation patterns were analyzed using the methylation-sensitive amplified polymorphism technique on biopsy samples collected from animals of both ecotypes. We found consistent differences in DNA methylation patterns between coastal and offshore individuals. We also confirmed the genetic differences described in previous studies, indicating that the divergence between ecotypes has both genetic and epigenetic components. Our data show that it is possible to differentiate animals from the coastal and offshore ecotypes using DNA methylation markers, supporting the hypothesis that contrasting environments—which are decisive for the ecological divergence of these populations—lead to epigenetic modifications in common bottlenose dolphins.

The spread of the introduced ascidians Ciona robusta Hoshino &amp; Tokioka, 1967 and Rhodosoma turcicum (Savigny, 1816) in the southwestern Atlantic

Abstract New records of the introduced solitary ascidians, Ciona robusta and Rhodosoma turcicum, have been added to the southwestern Atlantic Ocean, from Cabo Frio to Ilha Grande Bay, Brazil, in surveys conducted since 2009. Both species occurred on natural and artificial substrates, in predator-protected habitats, and regions close to harbors or other maritime activities. The distribution of Ciona robusta was related to water temperature, influenced by upwelling intensity and temperatures below 25oC, while R. turcicum was not sensitive to the range of recorded water temperatures. The occurrence of both species on sites close to maritime terminals suggests vessels as potential vectors.

First record of the non-native medusa Blackfordia virginica (Hydrozoa, Leptomedusae) on the coast of Uruguay, Southwestern Atlantic

First record of the non-native medusa Blackfordia virginica (Hydrozoa, Leptomedusae) on the coast of Uruguay, Southwestern Atlantic

Morphology, genetics, and historical records support the synonymy of two ascidian species and suggest their spread throughout areas of the Southern Hemisphere

Taxonomic uncertainties and the lack of ecological knowledge can hinder the correct identification and the assignment of biogeographic status of marine species. The ascidian Asterocarpa humilis (Heller, 1878), originally described from New Zealand, has a broad distribution in shallow temperate areas of the Southern Hemisphere, having recently colonised areas of the Northern Hemisphere. A closely related species, Cnemidocarpa robinsoni Hartmeyer, 1916, has been reported in the South-Eastern Pacific and the South-Western Atlantic, and several authors considered it a junior synonym of A. humilis. We gathered for the first time morphological and genetic data from specimens from distant areas. We studied the morphology of specimens collected at seven locations of South America. We also re-examined specimens from museum collections and revised the available literature on these species. Genetic data were obtained from specimens from Argentina and compared with available sequences of A. humilis from Chile, New Zealand, England and France. Morphological and genetic analyses showed that all compared specimens were conspecific. Furthermore, specimens from different continents shared haplotypes and exhibited low genetic distance among them. These results, the biological characteristics of this ascidian, and its longstanding presence in different habitats from disjoint areas, allow us to question its native range. We support the idea that A. humilis is a cryptogenic and neocosmopolitan species that has been transported by maritime traffic through the Southern Hemisphere, revealing frequent processes of exchange through this wide area for more than a century, with presumably associated alterations in the marine biota.

Taxonomic Revision of Living Boring Bivalves Belonging to the Family Pholadidae Lamarck, 1809, (Bivalvia: Myida) from the Southwestern Atlantic.

Boring bivalves of the family Pholadidae Lamarck, 1809 living in Argentinean and Uruguayan waters are herein revised. The literature research revealed twelve nominal species of Pholadidae mentioned as living in the study area. Type material of all nominal taxa were examined when it was possible. Additional specimens from field works and malacological collections were studied, illustrated and re-described. Details of type localities, repositories, and distribution range are provided for each valid taxa. This work revealed the presence of five native and one introduced species belonging to Pholadidae in Argentinean and Uruguayan waters. Barnea (Anchomasa) lamellosa, Cyrtopleura (Scobinopholas) lanceolata, Pholas (Thovana) campechiensis and Martesia fragilis belonging to the Argentine biogeographical province; Netastoma darwinii from Magellan province; and Barnea (Anchomasa) truncata introduced in the Bahía Blanca estuary. Finally, morphological comparison with congeneric species distributed in American seas are provided.