443 results on '"southwest atlantic"'
Search Results
2. Long‐Term Variability in the Southwest Atlantic Marine Fishery Ecosystems in Relation to Climate Change.
- Author
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Liu, Hewei, Zhang, Ping, Cao, Jie, Yu, Wei, and Chen, Xinjun
- Subjects
- *
ATLANTIC multidecadal oscillation , *FISHERY resources , *FISHERIES , *ZONAL winds , *AIR speed - Abstract
ABSTRACT Exploring the impacts of climate variability on the marine fishery ecosystems in the Southwest Atlantic Ocean is conducive to establishing an ecosystem‐based approach for the protection and rational utilization of fishery resources. In this study, long‐term fisheries data, 23 environmental data from the entire Southwest Atlantic, and 25 global climate data have been used to explore the regime shift of the fishery ecosystem and the response of fishery resources to climate change from 1950 to 2018. The results indicated that changes in the Southwest Atlantic fishery ecosystem exhibited a significant nonstationary trend, and there were three noteworthy regime shifts in 1976/1977, the late 1980s, and the late 20th century. The temperature, sea surface height, water runoff, and cloudiness were the environmental variables with the greatest impact on fishery resources within the Southwest Atlantic Fishery Ecosystem, while zonal wind speed and air temperature yielded a more significant impact on low latitude areas. In terms of climate indices, fishery resources have the most obvious response to the Global Mean Land‐Ocean Temperature Index and Antarctic Sea Ice Extent, and the Atlantic Multidecadal Oscillation had an intense impact on low latitude areas concurrently. The study highlights the climate‐related nonstationary changes in the Southwest Atlantic fishery ecosystem. [ABSTRACT FROM AUTHOR]
- Published
- 2025
- Full Text
- View/download PDF
3. Historical fishing regimes uncover deep-sea productivity hotspots in the SW Atlantic Ocean.
- Author
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Perez, Jose Angel A., Gavazzoni, Lucas, and Sant'Ana, Rodrigo
- Subjects
FISH conservation ,BIOLOGICAL transport ,SEDIMENTARY basins ,BIOTIC communities ,SPECIES pools ,DEEP-sea fishes - Abstract
In the deep-sea, abundant and diverse biological communities tend to occur in areas where combinations of geological, physical and biological processes locally enhance trophic-wide productivity, sustaining aggregations of consumers and top predators. These areas are 'productivity hotspots' and their delimitation should improve the effectiveness of area-based strategies designed to manage human activities and protect the deep-sea. We explored the premise that fishing operations in association with geomorphological features are effective surrogates for delimiting productivity hotspots distribution in the Brazilian Meridional Margin (BMM; 18°S - 35°S; 200 – 3300 m). We described along-slope and across-slope geoforms and related them with catch patterns of fishes, deep-sea shrimps, deep-sea crabs and squids in 23565 fishing hauls conducted between 2000 and 2007. Over 97% of the total catch was obtained in Santos (42.7%) and Pelotas (54.8%) sedimentary basins. In the former, 55.7% of all fishing hauls and 38.6% of the catch were obtained from one of 12 slope geoforms, which covered 22% of the available fishing area. In the Pelotas basin, a shelf break geoform covering 6% of the fishing area concentrated 29.5% of the fishing hauls and 30.2% of the catch. Best fit delta-lognormal Generalized Linear Models (explaining >50% of the total variance) highlighted the positive effect of shelf break embayments of Santos Basin in occurrence and abundance of the pool of species targeted by fisheries. Within these embayments, sectors incurvated and excavated by erosive action of the Brazil Current positively affected abundance and occurrences of fishes and deep-sea shrimps, respectively. The upper slope (300 – 500 m depths) were particularly favorable for fishes and squid concentrations, whereas the lower slope (600 – 800 m depths) increased the probability of deep-sea shrimp catches. We propose that the Santos Basin shelf break embayments host mesoscale and sub-mesoscale productivity hotspots, sustained by biophysical processes promoted by the Brazil Current flow, coupled with biological active transport of pelagic and demersal vertical migrators, some of them targeted by bottom fisheries. We advocate that these are unique features, in the otherwise oligotrophic SW Atlantic subtropical gyre, that should be taking into consideration in regional systematic conservation plans. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
4. Molecular phylogeny, including a new species of Anindobothrium (Cestoda, Rhinebothriidea) from the Southern eagle ray Myliobatis goodei, finally solves the taxonomic enigma of Phyllobothrium myliobatidis.
- Author
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García Facal, Guillermina, Franzese, Sebastián, Montes, Martín Miguel, and Menoret, Adriana
- Subjects
- *
TERRITORIAL waters , *TESTIS , *STINGRAYS , *PHYLOGENY , *TAPEWORMS , *SPECIES - Abstract
During a parasitological survey of tapeworms from Myliobatis goodei Garman, 1885 (Myliobatiformes: Myliobatidae) in coastal waters off Argentina in the Southwestern Atlantic, a new rhinebothriidean cestode species, Anindobothrium danielae sp. nov., is described using morphological and molecular techniques. This species differs from its congeners by a particular combination of features, including the configuration of the bothridia, the number of marginal loculi, and the number and distribution of testes. Additionally, Anindobothrium myliobatidis comb. nov. is proposed based on several morphological traits, including the presence of stalked bothridia with marginal loculi and an apical sucker, euapolytic strobila, and postvaginal testes. The diagnosis of the genus Anindobothrium Marques, Brooks & Lasso, 2001 is amended to include the features exhibited by these two species; two species subsets are suggested based on the configuration of the bothridia. The presence of A. danielae sp. nov. and A. myliobatidis comb. nov. in the studied area not only increases the number of cestodes in M. goodei here from eight to ten but also represents the first report of a rhinebothriidean cestode parasitizing stingrays of the family Myliobatidae in the Southwestern Atlantic. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
5. First Reports on Reproductive Traits of the Endemic Southwestern Atlantic Rio Skate Rioraja agassizii (Rajiformes, Arhynchobatidae) in Captivity.
- Author
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Lenain, Victoria M., Matusevich, Florencia, Gabbanelli, Valeria, Vazquez, Diego M., Awruch, Cynthia A., Díaz de Astarloa, Juan M., and Mabragaña, Ezequiel
- Subjects
SEXUAL cycle ,FERTILITY ,CAPTIVITY ,EMBRYOS ,BIOLOGY - Abstract
This study provides novel data on fecundity and oviposition rate of Rioraja agassizii and complementary information on incubation period in captivity. Two females of R. agassizii were maintained in captivity over 1‐year period. Oviposition rate was 0.28 and 0.26 egg cases per day, and fecundity was 114 and 92 egg cases for each female. Incubation period was determined for two embryos resulting in 105 and 114 days with average incubation temperatures ranging from 17.5°C (± 0.81) to 22.1°C (± 1.32). Captive studies contribute to a better understanding of the reproductive biology and complement investigations carried out in the wild. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
6. First record of a pectoral-fin abnormality in the broadnose skate Bathyraja brachyurops (Elasmobranchii, Arhynchobatidae).
- Author
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Laurentxena, María M. and Storni, Benjamín
- Subjects
HEAVY metal toxicology ,PECTORAL fins ,COMPETITION (Biology) ,CHONDRICHTHYES ,BEAKS - Abstract
The first case of a morphological abnormality in the broadnose skate Bathyraja brachyurops is reported. The specimen was captured by a vessel fishing in the Southwest Atlantic Ocean off the coast of Argentina. Radiographs and mammographs were used to visualize the abnormality in greater detail. The specimen exhibited a lack of union between both pectoral fins and the head region. Ventral photographs revealed that the propterygia does not articulate with the antorbital cartilage or there is a malformation in the antorbital cartilage. It could cause the pectoral fins to be incomplete. The rest of the body seemed to have developed normally, with the rostrum, the other fins, and the caudal area showing no abnormalities. Even though it is difficult to assess the causes of the abnormalities, it is believed that they may be due to environmental factors, such as heavy metal pollution. The pectoral-fin deformity could interfere with locomotion, feeding, or mating, affecting intraspecific competition. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
7. Early development of smallscale weakfish Cynoscion microlepidotus (Cuvier, 1830) (Sciaenidae: Teleostei)
- Author
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Ohkawara, Márcio H., Gonsales, Sílvia A., Dias, June F., Contente, Riguel F., Bonecker, Ana C. T., Lourdes Zani‐Teixeira, Maria, Katsuragawa, Mario, and Namiki, Cláudia
- Subjects
- *
FISH larvae , *SCIAENIDAE , *OSTEICHTHYES , *MORPHOLOGY , *SPINE - Abstract
Larval and transforming stages of smallscale weakfish Cynoscion microlepidotus (Sciaenidae) are described and illustrated based on samples obtained in three different sites along the Brazilian coast: São Marcos Bay (Maranhão state), Camamu Bay (Bahia state), and the Cananéia‐Iguape Estuarine System (São Paulo state). Identification of early stages of C. microlepidotus was based on meristic counts, such as number of myomeres (22), number of fin spines and rays (dorsal XI, 24, anal II, 9 and pectoral 19), morphological features (presence of supraoccipital crest in larvae from flexion to transformation stages, branched anal fin spines) and pigmentation pattern. Early stages of this species are likely to be confused with Carangidae and Scorpaenidae due to the presence of a supraoccipital crest, and with the Sciaenidae species Stellifer rastrifer, Macrodon atricauda, M. ancylodon, and Isopistus parvipinnis due to branched anal fin elements. However, a distinction can be made when analyzing the set of characters (morphology, morphometry, pigmentation) in relation to the different stages of development. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
8. Historical fishing regimes uncover deep-sea productivity hotspots in the SW Atlantic Ocean
- Author
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Jose Angel A. Perez, Lucas Gavazzoni, and Rodrigo Sant’Ana
- Subjects
productivity hotspots ,Southwest Atlantic ,deep-sea conservation ,deep-sea fisheries ,seabed modelling ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
In the deep-sea, abundant and diverse biological communities tend to occur in areas where combinations of geological, physical and biological processes locally enhance trophic-wide productivity, sustaining aggregations of consumers and top predators. These areas are ‘productivity hotspots’ and their delimitation should improve the effectiveness of area-based strategies designed to manage human activities and protect the deep-sea. We explored the premise that fishing operations in association with geomorphological features are effective surrogates for delimiting productivity hotspots distribution in the Brazilian Meridional Margin (BMM; 18°S - 35°S; 200 – 3300 m). We described along-slope and across-slope geoforms and related them with catch patterns of fishes, deep-sea shrimps, deep-sea crabs and squids in 23565 fishing hauls conducted between 2000 and 2007. Over 97% of the total catch was obtained in Santos (42.7%) and Pelotas (54.8%) sedimentary basins. In the former, 55.7% of all fishing hauls and 38.6% of the catch were obtained from one of 12 slope geoforms, which covered 22% of the available fishing area. In the Pelotas basin, a shelf break geoform covering 6% of the fishing area concentrated 29.5% of the fishing hauls and 30.2% of the catch. Best fit delta-lognormal Generalized Linear Models (explaining >50% of the total variance) highlighted the positive effect of shelf break embayments of Santos Basin in occurrence and abundance of the pool of species targeted by fisheries. Within these embayments, sectors incurvated and excavated by erosive action of the Brazil Current positively affected abundance and occurrences of fishes and deep-sea shrimps, respectively. The upper slope (300 – 500 m depths) were particularly favorable for fishes and squid concentrations, whereas the lower slope (600 – 800 m depths) increased the probability of deep-sea shrimp catches. We propose that the Santos Basin shelf break embayments host mesoscale and sub-mesoscale productivity hotspots, sustained by biophysical processes promoted by the Brazil Current flow, coupled with biological active transport of pelagic and demersal vertical migrators, some of them targeted by bottom fisheries. We advocate that these are unique features, in the otherwise oligotrophic SW Atlantic subtropical gyre, that should be taking into consideration in regional systematic conservation plans.
- Published
- 2024
- Full Text
- View/download PDF
9. Revision of the genus Oxyarcturus (Isopoda, Valvifera, Antarcturidae), with a description of a new deep-sea species from Argentina
- Author
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Pereira, Emanuel, Roccatagliata, Daniel, Doti, Brenda, and Pensoft Publishers
- Subjects
Mar del Plata submarine canyon ,Oxyarcturus beliaevi (Kussakin 1967) ,Oxyarcturus dubius (Kussakin 1967) ,Oxyarcturus holoacanthus sp. nov ,Southwest Atlantic - Published
- 2023
10. Edad y crecimiento del tiburón gatuzo Mustelus schmi?i (Carcharhiniformes, Triakidae) en aguas costeras de la provincia de Chubut, Patagonia, Argentina.
- Author
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Navoam, Ximena, Bovcon, Nelson D., Suárez, Matías, and Pasti, Alessandra
- Subjects
- *
MUSTELUS schmitti , *SHRIMP fisheries , *FISHERIES , *SHARK anatomy , *CHONDRICHTHYES , *SHARK behavior , *VERTEBRAE , *LONGEVITY - Abstract
The narrownose smooth-hound, Mustelus schmitti (Carcharhiniformes, Triakidae) is an endemic shark of the southwest Atlantic Ocean and it is listed as critically endangered by the IUCN. The age and growth of M. schmitti were studied using vertebrae of 102 females and 121 males caught as by-catch by the bottom-trawl shrimp fishery and by coastal sport anglers in Central Patagonia (43-44° S). The maximum ages observed for females and males were 18 and 16 years, respectively. Seven growth (size-at-age) models were fitted. The two-phase von Bertalanffy model presented the best fit for females and males. There were no differences in growth between sexes. Growth parameters were asymptotic length (L∞)=916 mm; growth coefficient (k)=0.12 years-1; age at which the transition between the two growth phases occurs (th)=5.26 years; length at birth (L0)=283.03 mm, and longevity (tmax)=21.92 years. The age at sexual maturity was estimated at 8.86 and 8.48 years for females and males, respectively. M. schmitti exhibits moderate growth, relatively long lifespan and late maturity, like other elasmobranchs characterized as extremely vulnerable. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
11. Sea turtle bycatch in Argentina: A qualitative assessment in commercial vessels.
- Author
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Jones, Sofía, Calvo, Rodrigo, Rolón, Melisa Celia Jazmin, Tettamanti, Germán, Vera, David Gustavo, and Prosdocimi, Laura
- Subjects
BYCATCHES ,SEA turtles ,DREDGING (Fisheries) ,LOGGERHEAD turtle ,CONTINENTAL shelf ,FISHERIES - Abstract
1. The Northern Argentine continental shelf is a sea turtle feeding ground that overlaps with important fisheries. Few studies assessed bycatch impact, especially on commercial vessels. 2. This work documents sea turtles' bycatch, fishery involved, species captured and crew actions. 3. Bycatch in four fisheries were registered at the 107 interviews to fishers conducted between 2021 and 2023, showing the urgency to research bottom trawling for demersal multi‐species. Fishers frequently recognize Caretta caretta, and positive and negative practices towards animals have been documented on‐board. 4. These results will help focus researches on fisheries with the greatest impact on sea turtles in the region. They also underscore the necessity for implementing commercial vessel monitoring programmes and improving on‐board handling practices. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
12. Supplementary description and ontogenetic variability of Coryphaenoides affinis: rediscovery of the species after 145 years since its original description (Teleostei: Gadiformes: Macrouridae).
- Author
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Prokofiev, Artem M.
- Subjects
- *
SPECIES , *GROUNDFISHES , *CALANOIDA - Abstract
A large adult (138 mm head length) of the grenadier genus Coryphaenoides is described. It is identified as C. affinis hitherto known only from two juvenile type specimens collected by HMS Challenger off Uruguay in 1876. The diagnosis of the species is revised to include the discovery of considerable ontogenetic changes in squamation. Spinulation on the body scales are reduced or lost with size, while the armament of the head scales become amplified. The larger of the syntype specimens is designated as the lectotype. All three known specimens of C. affinis were collected in the southwestern Atlantic at depths between 3500 and 4000 m. A key for identification for the species of the subgenus Nematonurus is provided. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
13. Satellite tagging confirms long distance movement and fast dispersal of Patagonian toothfish (Dissostichus eleginoides) in the Southwest Atlantic.
- Author
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Eunjung Kim, Chi Hin Lam, Gyum Joon Park, and Jong Hee Lee
- Subjects
WATER temperature ,HABITATS - Abstract
Introduction: To better understand Patagonian toothfish (Dissostichus eleginoides) movement and habitat in the Southwest Atlantic, fifty popup satellite archival tags (PSATs) were deployed off Davis Bank on North Scotia Ridge between 2019 and 2020 on individuals ranging from 97-139 cm total length. Methods: PSATs (18 Lotek Wireless PSATFLEX and 32 Wildlife Computers MiniPAT) were programmed to detach after completing 1 to 16-month missions recording pressure (depth) and water temperature. Results: Six tags failed to report, and among the remaining 44 reporting tags, 34 reported on schedule, up to 487 days at sea - the longest electronic tag deployment for this species to date. Although the majority of PSATs reported within 50 km from the release sites, confirming high site fidelity, 12% of tags reported more than 200 km away, showing connectivity to Shag Rocks and South Georgia in the Southern Ocean. Toothfish moved across the Antarctic Polar Front through/to areas with no fishing activities, and hence, explained the absence of any previous conventional tag recapture. A 1-month transit to the Falkland/Malvinas Plateau Basin also revealed that toothfish can attain a surprisingly high movement rate of 33 km day-1. Discussion: Fishery independent examples of toothfish presence and their movement capabilities are inviting us to broaden our examination on how toothfish move around their Scotia Arc habitats and link up different regional aggregation sites in the South Atlantic. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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14. 阿根廷滑柔鱼雄性个体的能量积累特点及与环境因子关系.
- Author
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刘 伟, 臧 娜, and 林东明
- Abstract
Copyright of Journal of Hydrobiology / Shuisheng Shengwu Xuebao is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2024
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15. Age, growth and maturity of an endemic valuable resource, the Rio skate (Rioraja agassizii (Chondrichthyes: Rajiformes)), off Uruguay and northern Argentina.
- Author
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Bianchi, Santiago J., Roman, Jorge M., Lucifora, Luis O., Barbini, Santiago A., and Wetherbee, Bradley
- Abstract
Context. Rioraja agassizii is a vulnerable species endemic to the Southwest Atlantic. It is caught by trawl fisheries throughout its range. Aims. To determine the age, estimate growth parameters, and age and size at maturity. Methods. Ages were determined using vertebrae readings. To fit growth models, a Bayesian framework was employed with the von Bertalanffy, Gompertz and Logistic candidate models. To estimate age and size at maturity, a logistical ogive was fitted to binomial maturity data. Key results. Maximum ages determined for males and females were 12 and 11 years respectively. The von Bertalanffy model was selected as the best one and there were no differences between sexes (mean parameters: L
∞ = 684.8 mm, k = 0.33 years-1 and L0 = 105.5 mm). Age and size at maturity were estimated at 3.31 and 4.55 years, and 485.02 and 544.55 mm TL for males and females respectively. Conclusions. Rioraja agassizii has a moderate growth rate and age at maturity was similar to those of skate species with a similar body size. Implications. Because skate species have different maximum ages, growth rates and maturity parameters, we strongly recommend urgent species-specific management measures for the pool of skate species exploited in Argentina. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
16. Prediction of the Relative Resource Abundance of the Argentine Shortfin Squid Illex argentinus in the High Sea in the Southwest Atlantic Based on a Deep Learning Model
- Author
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Delong Xiang, Yuyan Sun, Hanji Zhu, Jianhua Wang, Sisi Huang, Haibin Han, Shengmao Zhang, Chen Shang, and Heng Zhang
- Subjects
Illex argentinus ,southwest Atlantic ,ensemble learning ,deep learning ,relative resource abundance ,Veterinary medicine ,SF600-1100 ,Zoology ,QL1-991 - Abstract
To analyze the impact of the marine environment on the relative abundance of Illex argentinus (high and low categories) in the southwest Atlantic, this study collected logbook data from Chinese pelagic trawlers from December 2014 to June 2024, including vessel position data and oceanographic variables such as sea surface temperature, 50 m and 100 m water temperature, sea surface salinity, sea surface height, chlorophyll-a concentration, and mixed layer depth. Vessel positions were used to enhance the logbook data quality, allowing an analysis of the annual trends in the resource center of this squid at a spatial resolution of 0.1° × 0.1° and a temporal resolution of ten days. The findings showed that the resource center is primarily located around 42° S in the north and between 45° S and 47° S in the south, with a trend of northward movement during the study period. Additionally, we constructed two ensemble learning models based on decision trees—AdaBoost and PSO-RF—aiming to identify the most critical environmental factors that affect its resource abundance; we found that the optimal model was the PSO-RF model with max_depth of 5 and n_estimators of 46. The importance analysis revealed that sea surface temperature, mixed layer depth, sea surface height, sea surface salinity, and 50 m water temperature are critical environmental factors affecting this species’ resources. Given that deep learning models generally have shorter running times and higher accuracy than other models, we developed a CNN-Attention model based on the five most important input factors. This model achieved an accuracy of 73.6% in forecasting this squid for 2024, predicting that the population would first appear near the Argentine exclusive economic zone around mid-December 2023 and gradually move east and south thereafter. The predictions of the model, validated through log data, maintained over 70% accuracy during most periods at a time scale of ten days. The successful construction of the resource abundance forecasting model and its accuracy improvements can help enterprises save fuel and time costs associated with blind searches for target species. Moreover, this research contributes to improving resource utilization efficiency and reducing fishing duration, thereby aiding in lowering carbon emissions from pelagic trawling activities, offering valuable insights for the sustainable development of this species’ resources.
- Published
- 2024
- Full Text
- View/download PDF
17. Disarticulated ossicles of sea cucumbers from the Campos Basin, Brazil: A new perspective into the discovery of diversity of Holothuroidea (Echinodermata).
- Author
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Martins, Luciana, Costa, Karen Badaraco, and Toledo, Felipe
- Subjects
- *
SEA cucumbers , *ECHINODERMATA , *MARINE sediments , *HOLOCENE Epoch , *BIOSTRATIGRAPHY - Abstract
The study of disarticulated ossicles of recent sea cucumbers from Campos Basin, Rio de Janeiro, Brazil, from various Holocene strata, obtained by micropaleontological methods, resulted in the identification of at least eight holothurian taxa, belonging to the five of the seven orders of Holothuroidea: Apodida (Synaptidae, Chiridotidae), Dendrochirotida (Psolidae and Cucumariidae), Holothuriida (Holothuria), and Molpadiida (Molpadiidae, Eupyrgidae). Our paper endorses the importance of studies of recent fauna based on isolated ossicles for taxonomy, biostratigraphy, and ecology. This study represents the first effort at the study of recent fauna of sea cucumbers based on the analysis of preserved ossicles in marine sediments. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
18. Dynamic Structure of Eddies of the Brazil‐Malvinas Confluence Zone Revealed by Direct Measurements and Satellite Altimetry.
- Author
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Frey, D. I. and Kubryakov, A. A.
- Subjects
EDDIES ,SURFACE waves (Seismic waves) ,ACOUSTIC Doppler current profiler ,ORBITAL velocity ,MESOSCALE eddies ,ALTIMETRY ,CONTINENTAL slopes - Abstract
The goal of this work is to study the dynamical structure of eddies of the Brazil‐Malvinas Confluence zone (BMC eddies) using direct velocity measurements carried out by Shipborne Acoustic Doppler Current Profiler during five oceanographic cruises performed in 2016–2022. In total, in situ data of 13 BMC eddies, including nine anticyclones and four cyclones are available. These data show that the orbital velocity in such eddies can reach 189 cm/s and their vertical structure is highly barotropic. In several eddies, the velocities exceeding 100 cm/s are observed down to a depth of 560 m and at a depth of 800 m they are still higher than 80 cm/s. The spatial structure of velocity and horizontal shear in the eddies is strongly asymmetric, with higher velocities in the southern part near the intense thermohaline BMC front. Altimetry data show qualitative agreement with in situ data, but underestimate the horizontal velocity shear and the maximum velocities at the periphery of the BMC eddies. We also use satellite altimetry and Argo float measurements to study these eddies, and estimate their impact on the thermohaline structure. The analysis shows that the eddies with orbital velocities exceeding 100 cm/s cause intense temperature and salinity anomalies reaching 7–9°C and 1 psu in anticyclones and −4°C and 0.8 psu in cyclones at 100–300 m depth. Plain Language Summary: The Brazil and Malvinas currents are the main circulation patterns in the Southwest Atlantic. They flow along the South America continental slope toward each other and meet around 38°S generating a thermohaline front known as the Brazil‐Malvinas Confluence zone. Further downstream, both currents retroflect and instabilities generate mesoscale eddies. In this study, we combine new velocity measurements and satellite data for the analysis of the velocity structure and distribution of eddies in the Southwest Atlantic. The velocity observations were carried out across 13 eddies and revealed high velocities exceeding 100 cm/s even at depths greater than 500 m. While direct measurements provide accurate velocity structure in several crossed eddies, satellite altimetry covers the entire region, allowing us to estimate the mean statistical parameters of all eddies over a long period in 1993–2020. The results show that the study area is characterized by the strongest eddies in the western part of the South Atlantic with intense orbital velocities (more than 100 cm/s) reaching 600 m depth. The composite analysis of altimetry and Argo float data shows that such eddies cause very strong temperature and salinity anomalies and significantly affect the salt and heat content in the region. Key Points: The dynamic structure of 13 intense eddies in the Brazil‐Malvinas Confluence zone is investigated using direct Shipborne Acoustic Doppler Current Profiler measurementsThe maximum measured orbital velocity reaches 189 cm/s and the velocities exceeding 100 cm/s are observed down to a depth of 560 mSubsurface temperature and salinity anomalies in the intense eddies can reach 9°C and 1 psu [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
19. Species composition and assemblage analysis of fishes caught as bycatch by the Patagonian shrimp fishery in the southwest Atlantic
- Author
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MARÍA EVA GÓNGORA, JULIAN RUIBAL NÚÑEZ, PABLO DANIEL COCHIA, and NELSON DARÍO BOVCON
- Subjects
bycatch ,fish associations ,Pleoticus muelleri ,San Jorge gulf ,Southwest Atlantic ,Science - Abstract
Abstract Bottom trawl fishing is the most used worldwide gear generating large amounts of discards due to bycatch of a variety of species. Shrimp fisheries are recognized for their high incidence in global discards. In waters of Patagonia Argentina (43°S - 47°S) an industrial shrimp fishery of high economic value is developed whose target species is the Patagonian shrimp Pleoticus muelleri. The information presented in this study comprises a period of 12 years (2003-2014) and it was gathered by the On-board Observer Program. The Program collects information of all species captured in the fishing fleets. The data analyzed corresponds to the double-rigged otter trawler fleet and the coastal fleet. The fish bycatch composition was characterized in both fleets and the frequencies of occurrence of species and the assemblage areas were analyzed. A total of 101 fish species were identified (59 families) of which 69 were bony fishes, 29 cartilaginous fishes and three species of jawless fishes. The assemblages described correspond to coastal and deep waters, and they are integrated by temperate and subtropical species pointing out the area as an ecotonal zone.
- Published
- 2023
- Full Text
- View/download PDF
20. Marine aquaculture as a source of propagules of invasive fouling species.
- Author
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Lins, Daniel M. and Rocha, Rosana M.
- Subjects
MARICULTURE ,INTRODUCED species ,FOULING organisms ,MUSSEL culture ,SEAWATER salinity ,MYTILUS galloprovincialis ,BARNACLES - Abstract
Non-indigenous species tend to colonize aquaculture installations, especially when they are near international ports. In addition to the local environmental hazard that colonizing non-indigenous species pose, they can also take advantage of local transport opportunities to spread elsewhere. In this study, we examined the risk of the spread of eight invasive fouling species that are found in mussel farms in southern Brazil. We used ensemble niche models based on worldwide occurrences of these species, and environmental variables (ocean temperature and salinity) to predict suitable areas for each species with three algorithms (Maxent, Random Forest, and Support Vector Machine). As a proxy for propagule pressure, we used the tonnage transported by container ships from Santa Catarina (the main mariculture region) that travel to other Brazilian ports. We found that ports in the tropical states of Pernambuco, Ceará, and Bahia received the largest tonnage, although far from Santa Catarina and in a different ecoregion. The ascidians Aplidium accarense and Didemnum perlucidum are known from Bahia, with a high risk of invasion in the other states. The bryozoan Watersipora subtorquata also has a high risk of establishment in Pernambuco, while the ascidian Botrylloides giganteus has a medium risk in Bahia. Paraná, a state in the same ecoregion as Santa Catarina is likely to be invaded by all species. A second state in this region, Rio Grande do Sul, is vulnerable to A. accarense, the barnacle Megabalanus coccopoma, and the mussel Mytilus galloprovincialis. Climate change is changing species latitudinal distributions and most species will gain rather than lose area in near future (by 2050). As an ideal habitat for fouling organisms and invasive species, aquaculture farms can increase propagule pressure and thus the probability that species will expand their distributions, especially if they are close to ports. Therefore, an integrated approach of the risks of both aquaculture and nautical transport equipment present in a region is necessary to better inform decision-making procedures aiming at the expansion or establishment of new aquaculture farms. The risk maps provided will allow authorities and regional stakeholders to prioritize areas of concern for mitigating the present and future spread of fouling species. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
21. Chondrichthyans from the southern tip of South America with emphasis on the marine protected area Namuncurá-Burdwood Bank: exploring egg nursery grounds.
- Author
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Florencia, Matusevich, Vazquez, Diego Martín, Gabbanelli, Valeria, Díaz de Astarloa, Juan Martín, and Mabragaña, Ezequiel
- Subjects
MARINE parks & reserves ,CHONDRICHTHYES ,EGG cases (Zoology) ,FISH eggs ,EGGS - Abstract
The Burdwood Bank (BB) is a subantarctic area, where two of the three Marine Protected Areas (MPA) of the Argentinean Exclusive Economic Zone are located: Namuncurá I, and Namuncurá II. The area is characterized by a high biodiversity of benthic invertebrates and teleost fishes; however, the available information on oviparous chondrichthyans is scarce. The aim of this study is to explore the potential reproductive use that oviparous chondrichthyans could make of the area based on the presence of egg-laying grounds. Additionally, we aim to provide an updated checklist of the species that inhabit the BB. Samples of specimens and egg capsules collected in four research cruises carried out between 2016 and 2018 were analyzed. Six skate species were found in both MPAs: Amblyraja doellojuradoi, Bathyraja albomaculata, B. brachyurops, B. macloviana,B. scaphiops, and Psammobatis rudis; whereas B. cousseauae, and B. magellanica were found exclusively in Namuncurá I, and B. multispinis in Namuncurá II. Here we report, for the first time, the presence of egg-laying grounds for five chondrichthyan species in the BB area: A. doellojuradoi, B. brachyurops, B. macloviana, B. scaphiops, and P. rudis. The results obtained highlighted the importance of the region for the conservation of oviparous chondrichthyans found in the southern Patagonian shelf. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
22. Legal perspectives on unintended and unsanctioned humpback whale entanglement in the South Atlantic trawl fishery.
- Author
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Aranha, Leandro and Torres-Florez, Juan Pablo
- Subjects
HUMPBACK whale ,FISHERIES ,ENVIRONMENTAL crimes ,FISH conservation ,TRAWLING - Abstract
Whale interactions with fishing gear pose a major anthropogenic threat, yet entanglements in South Atlantic trawl fisheries remain underreported, with no published records. This lack of data extends to reports of whales found stranded with amputated tails, despite documented cases of survival even without a fluke. This study presents a novel case: a video recorded in May 2020 captured a shrimp trawler in Santa Catarina, Brazil, entangled with a humpback whale (Megaptera novaeangliae). Vocalizing and bleeding, the whale had recently lost its fluke and remained caught in the vessel's gear. Following the video's public outcry, authorities identified and apprehended the responsible vessel, conducting a thorough investigation. Although initial sanctions were issued, and evidence confirmed illegal fishing practices and neglect towards the whale, subsequent legal proceedings deemed the act unintentional and acquitted the involved parties. This report seeks to not only document this unprecedented case but also to analyze why such infractions against cetacean often receive minimal legal consequences. Examining this case within the context of broader policy and enforcement frameworks, we discuss potential explanations for the perceived low legal severity of such incidents and argue for the need for enhanced legal accountability to effectively protect marine mammals in the South Atlantic. [Display omitted] • First recorded humpback whale entangled in the South Atlantic trawling gear, exposing gaps in environmental laws and legal cases. • The incident highlights fishings'' threats to whales, exacerbated by underreporting and weak legal action, despite being unintentional. • The analysis calls for stronger laws and penalties to better address environmental infractions, ensuring consistent legal enforcement. • Call for education and training for fishermen and fisheries managers to prevent entanglements and promote whale conservation. • The paper advocates urges collaboration between the fishing industry, regulatory bodies, and conservationist for solutions balancing conservation and with sustainable fishing. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
23. Deep-sea living (stained) benthic foraminifera from the continental slope and São Paulo Plateau, Santos Basin (SW Atlantic): ecological insights.
- Author
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Araújo, Beatriz D., Yamashita, Cintia, Santarosa, Ana C. A., Rocha, Amanda V., Vicente, Thaisa M., Mendes, Rafaela N. M., Passos, Camila C., Alves Martins, Maria Virginia, and Sousa, Silvia Helena M.
- Subjects
CONTINENTAL slopes ,FORAMINIFERA ,BIOTIC communities ,MULTIVARIATE analysis ,WATER depth ,FOOD quality ,PLATEAUS - Abstract
This study aimed to characterize the spatial distribution and composition of living Benthic Foraminifera (BF) and to comprehend how environmental conditions (e.g., organic matter) can affect communities of these protozoa in the northern and southern sectors of the Santos Basin (SB), in the continental slope and São Paulo Plateau. In this context, 23 stations (65 samples including replicates at each station) were collected between 400 and 2,400 m water depth. Multivariate analyses revealed that the ecological structure of the community changes mainly along the bathymetric gradients. Stations located between 400 and 700 m, both in northern and southern sectors, are characterized by the presence of indicator species of high intensity of currents, such as Globocassidulina subglobosa and Trifarina bradyi. These stations are also mainly marked by the occurrence of Epistominella exigua, a phytodetritivore species. The stations at 1,000 and 1,300 m depth, in both sectors, are characterized by high accumulation of organic matter in the sediments, which favors the development of agglutinated foraminifera species, such as those of the genus Reophax. Finally, the lower slope and the São Paulo Plateau, in both sectors, are oligotrophic regions, with pulses of labile organic carbon, probably low current velocities and the presence of Alabaminella weddellensis. The quantity and quality of food, which are closely related to hydro-sedimentary dynamics and bentho-pelagic coupling in the slope and São Paulo Plateau, are the main factors that influence the distribution of living BF assemblages in the SB. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
24. On the trophic role of pelagic fishes and fishery landings shifts in the South Brazil Bight.
- Author
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Olher, Julia Petroski and Gasalla, Maria A.
- Subjects
FISHERY management ,FISHERIES ,FOOD chains ,BIOMASS ,GASTROINTESTINAL contents ,SARDINES ,PELAGIC fishes ,COPEPODA - Abstract
Knowledge of the feeding habits of pelagic fishes off the Brazilian coast is scarce, making the analysis of trophic interactions often inaccurate. Here, we investigated the diet and trophic role of 12 pelagic fish species by revisiting samples obtained by the ECOSAR II Program (FURG/IO/IBAMA) between 23°S and 28°40'S, an area also known as South Brazil Bight. In addition, we analyzed their biomass and fisheries landings in order to examine shifts over time. The content of 432 stomachs was analyzed at the lowest taxonomic level possible. The frequencies of occurrence were used to cluster species, revealing three trophic guilds: "Planktivorous Clupeiformes", "Planktivorous Carangiformes", and "Piscivores". Most Carangidae consumed mainly copepods and other small crustaceans, except Selene setapinnis which clustered in the piscivorous guild together with Scombriformes specimens. In terms of biomass, the dominance of Trachurus lathami, Sardinella brasiliensis, and Trichiurus lepturus was evident. The species' trophic levels ranged from 2.98 to 4.5, showing that these fishes occupied intermediate to high trophic position. Comparing fisheries landings in two study periods (1986-2002 and 2003-2019), six species showed a decrease, while three an increase. Correlations between landings of the Brazilian sardine (Sardinella brasiliensis) and other pelagic fishes indicate that when the former's decreases, the catch of alternative species, such as Opisthonema oglinum and Chloroscombrus chrysurus, increases. The intermediate position of small pelagics in the food web may affect the availability of commercial species by controlling the abundance of lower and upper trophic-level organisms. These findings fill essential gaps for ecosystem modeling, suggesting that ecosystembased fisheries management should address multispecies issues of the pelagic realm rather than only single-species approaches. Combining past survey data with yield trends provides evidence for both natural and human-induced ocean changes. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
25. Changes in the Specific and Biogeographic Composition of Coastal Fish Assemblages in Patagonia, Driven by Climate Change, Fishing, and Invasion by Alien Species
- Author
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Galván, David E., Bovcon, Nelson D., Cochia, Pablo D., González, Raúl A., Lattuca, María E., Reinaldo, Matías Ocampo, Rincón-Díaz, Martha P., Romero, María Alejandra, Vanella, Fabián A., Venerus, Leonardo A., Svendsen, Guillermo Martín, Quintana, Flavio, Series Editor, Avila, Luciano J., Series Editor, González-José, Rolando, Series Editor, Bucci, Sandra J., Series Editor, Walter Helbling, E., editor, Narvarte, Maite A., editor, González, Raul A., editor, and Villafañe, Virginia E., editor
- Published
- 2021
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26. Input of Terrestrial Material into Coastal Patagonian Waters and Its Effects on Phytoplankton Communities from the Chubut River Estuary (Argentina)
- Author
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Vizzo, Juan I., Cabrerizo, Marco J., Villafañe, Virginia E., Helbling, E. Walter, Häder, Donat-P., editor, Helbling, E. Walter, editor, and Villafañe, Virginia E., editor
- Published
- 2021
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27. First records of Macgillivray’s prion Pachyptila macgillivrayi in Uruguayan and Argentine waters
- Author
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Muñoz, Joaquín, Savigny, Christian, Castelli, Diego, and Jiménez, Sebastián
- Published
- 2023
- Full Text
- View/download PDF
28. Feeding ecology of the longtail southern cod, Patagonotothen ramsayi (Regan, 1913) (Notothenioidei) in the Marine Protected Area Namuncurá-Burdwood Bank, Argentina.
- Author
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Fischer, Luciana, Covatti Ale, Marina, Deli Antoni, Mariana, Díaz de Astarloa, Juan Martín, and Delpiani, Gabriela
- Subjects
MARINE parks & reserves ,PREDATION ,POLYCHAETA ,FEED analysis ,FOOD chains ,AMPHIPODA - Abstract
Patagonotothen ramsayi has the highest concentrations at Burdwood Bank, playing a key ecological role in the demersal food web. The aim of this study was to describe and analyze the feeding ecology of longtail southern cod in the Marine Protected Area Namuncurá-Burdwood Bank (MPAN-BB). From 369 specimens sampled, 229 (62.06%) contained food. Prey-specific index of relative importance (%PSIRI) for each prey was calculated showing that P. ramsayi preyed mainly on polychaetes (21.07%), amphipods (14.89%), other crustaceans (13.25%), and decapods (11.62%). The analysis of the feeding strategy confirms that P. ramsayi is a generalist feeder. The effect of sex, ontogenetic stage, total length (TL), and capture depth was evaluated using generalized linear models. All prey categories were independent of sex, while a differential consumption of isopods and polychaetes according to the ontogenetic stage was observed. Isopods were more consumed by juveniles, while polychaetes were fed by adults. The intake of amphipods and decapods was not influenced by any of the studied variables. Regarding capture depth, the consumption of euphausiids and polychaetes was higher in shallower areas, in contrast to teleost and isopods that were more ingested at greater depths. Finally, the intake of euphausiids, teleosts, and polychaetes was positively influenced by the total length of the predator, while the consumption of other invertebrates was negatively related. It may be concluded that Patagonotothen ramsayi in the MPAN-BB has a generalist diet and demersal-benthic feeding habits, changing its diet with total length and depth of capture. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
29. Seasonality of phytoplankton community and dynamics of autotrophic carbon in a cold temperate port (Argentina).
- Author
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Barbosa, Romina Vanessa, Halac, Silvana, Schwindt, Evangelina, and Tatián, Marcos
- Subjects
- *
COMMUNITIES , *SKELETONEMA costatum , *SPRING , *WINTER , *BIOMASS estimation , *FOOD chains , *PHYTOPLANKTON , *DINOFLAGELLATES - Abstract
The changes within and between seasons in phytoplankton composition and abundance determine the carbon biomass available for upper levels of the food web. Temporal changes in phytoplankton community and environmental parameters in a port in Puerto Madryn, Southwest Atlantic were analysed. During an annual period (2011–2012), samples of surface seawater were collected approximately monthly. We determined phytoplankton community structure (species composition and abundance) and biomass (determined by carbon content and chlorophyll a (Chl a)). Water temperature, salinity and transparency were measured when sampling the surface water and local meteorological data were considered. The main groups observed were diatoms (Bacillariophyta; the most abundant during the concentration peaks of Chl a), dinoflagellates (Dinophyta) and flagellates, which mainly included species of Cryptophyta and Chlorophyta. Diatoms exhibited blooms in March (summer–autumn) and September (spring), represented by Skeletonema costatum and Pseudo-nitzschia spp. respectively. Dinoflagellates contributed to the highest carbon biomass, with peaks in January (summer) and April (autumn), exemplified by Prorocentrum micans and Scrippsiella acuminata, respectively. Temporal differences in community composition were related to the seasonal changes in temperature, solar irradiance, precipitation, salinity and wind velocity. The environmental conditions seem not only to determine the species composition but also cell size distribution: nanoplanktonic (≤ 20 µm) species dominated mainly during late spring, summer and early winter while microplanktonic species (> 20 µm) during late winter and early spring. Our results showed within-season changes and show that not only Chl a, but also carbon content can be considered, as the former is a biased estimator of phytoplankton biomass. This study provides the first seasonally resolved estimation in the area of the carbon biomass available for upper levels of the food web and a necessary information for future scenarios prediction. HIGHLIGHTS• Two diatom blooms were followed by an increase in dinoflagellate abundance.• Annual environmental conditions drive the phytoplankton community structure.• First seasonally estimation of autotrophic biomass availability for Patagonian trophic web. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
30. Deep-Sea Pycnogonids from Uruguay: Every Deep Cruise Adds Valuable Information
- Author
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Soler-Membrives, A., Lucena, R. A., Company, J. B., Rotllant, G., and Hendrickx, Michel E., editor
- Published
- 2020
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31. Deep-sea movement patterns of the Patagonian toothfish Dissostichus eleginoides Smitt in the Southwest Atlantic.
- Author
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Lee, Brendon, Skeljo, Frane, Randhawa, Haseeb S., and Arkhipkin, Alexander
- Abstract
Context: Knowledge on movement patterns within marine fish populations are essential for understanding key aspects of their biology, distribution and stock structure. Many deep-sea fish species possess complex life-history patterns with distributions occurring across vast areas. The nature of connectivity at different life-history stages in a dynamic Patagonian toothfish population on the Patagonian Shelf, Slope and deep-sea plateau around the Falkland Islands remains speculative. Aims: We aimed to elucidate the movement patterns as well as the extent that these are driving connectivity during the adult life-history stages of Patagonian toothfish in the region. Methods: A 5+-year tag–recapture program was executed and data were analysed using generalised additive models. Key results: The majority of individuals (77.59%) displayed high site fidelity (<50 km), suggesting that seasonal spawning migrations are uncommon. However, 9.91% of individuals undertook large-distance movements across oceanographic and physical boundaries. These were characterised by large (>120 cm) fish inhabiting the slope and deep-sea plains (north of 52°S) undertaking southward (direction = 150–240°) home-range relocations to spawning areas. Conclusions and implications: The results provide compelling evidence to a single Patagonian toothfish metapopulation, with important considerations in terms of the spawning stock dynamics, and the development of regional management agreements across their Patagonian distribution. The current study describes the movement patterns that occur during the deep-sea life-history stages in a dynamic Patagonian toothfish population in the Southwest Atlantic. Results provide evidence of high site fidelity along with previously unrecorded connectivity pathways through the active movement of adults. These movement pathways link deep-sea foraging areas with spawning grounds, across physical and oceanographic barriers. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
32. Multilocus phylogeography of the endemic and endangered angular angelshark (Squatina guggenheim) in the Southwest Atlantic Ocean.
- Author
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Bunholi, Ingrid Vasconcellos, da Silva Ferrette, Bruno Lopes, Domingues, Rodrigo Rodrigues, Rotundo, Matheus Marcos, Cuevas, Juan Martín, García, Mirta, Gómez, Sebastián, de Freitas, Renato Hajenius Aché, Oliveira, Claudio, Foresti, Fausto, and Mendonça, Fernando Fernandes
- Subjects
- *
PHYLOGEOGRAPHY , *CYTOCHROME b , *CYTOCHROME oxidase , *OCEAN , *GENETIC variation , *GENE flow , *MICROSATELLITE repeats - Abstract
The angular angelshark (Squatina guggenheim) is a coastal endangered angel shark from the Southwest Atlantic Ocean and one of the major bycatch victims. Despite major concerns about this species, little is known about its evolutionary connectivity across its whole geographic distribution. Here, genetic connectivity and phylogeographic patterns of S. guggenheim for 122 individuals were assessed across the Southwest Atlantic Ocean regions based on a multilocus mitochondrial DNA approach to support conservation strategies. The concatenated mitochondrial dataset (control region, cytochrome b and cytochrome c oxidase I) showed high levels of haplotype diversity and low nucleotide diversity in S. guggenheim, with distinct genetic diversity patterns among populations. Although signs of stepping-stone gene flow were observed, a strong and statistically significant genetic structure into at least two populations was detected, matching with the species' biological traits and region's oceanographic particularities. Contrasting demographic patterns were detected, in which only southernmost Atlantic populations showed signs of population expansion. Despite the existence of connectivity among regions, our results suggest that conservation plans should be carried out following the uniqueness of each management unit. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
33. Unveiling the wasp-waist structure of the Falkland shelf ecosystem: the role of Doryteuthis gahi as a keystone species and its trophic influences
- Author
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Beauchene Fishing, European Commission, German Federal Agency for Nature Conservation, Büring, Tobias, van der Grient, Jesse, Pierce, Graham J., Bustamante, Paco, Scotti, Marco, Jones, Jessica B., Rocha, Francisco, Arkhipkin, A., Beauchene Fishing, European Commission, German Federal Agency for Nature Conservation, Büring, Tobias, van der Grient, Jesse, Pierce, Graham J., Bustamante, Paco, Scotti, Marco, Jones, Jessica B., Rocha, Francisco, and Arkhipkin, A.
- Abstract
The Falkland Shelf is a highly productive ecosystem in the Southwest Atlantic Ocean. It is characterized by upwelling oceanographic dynamics and displays a wasp-waist structure, with few intermediate trophic-level species and many top predators that migrate on the shelf for feeding. One of these resident intermediate trophic-level species, the Patagonian longfin-squid Doryteuthis gahi, is abundant and plays an important role in the ecosystem. We used two methods to estimate the trophic structure of the Falkland Shelf food web, focusing on the trophic niche of D. gahi and its impacts on other species and functional groups to highlight the importance of D. gahi in the ecosystem. First, stable isotope measurements served to calculate trophic levels based on an established nitrogen baseline. Second, an Ecopath model was built to corroborate trophic levels derived from stable isotopes and inform about trophic interactions of D. gahi with other functional groups. The results of both methods placed D. gahi in the centre of the ecosystem with a trophic level of ~ 3. The Ecopath model predicted high impacts and therefore a high keystoneness for both seasonal cohorts of D. gahi. Our results show that the Falkland Shelf is not only controlled by species feeding at the top and the bottom of the trophic chain. The importance of species feeding at the third trophic level (e.g. D. gahi and Patagonotothen ramsayi) and observed architecture of energy flows confirm the ecosystem's wasp-waist structure with middle-out control mechanisms at play
- Published
- 2024
34. Fish assemblage patterns in a subtropical estuary in southern Brazil.
- Author
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Cattani, André Pereira, Gerke, Yuri, Pichler, Helen Audrey, Adelir-Alves, Johnatas, Spach, Henry Louis, and Schwinge, Paulo Ricardo
- Subjects
- *
DREDGING (Fisheries) , *RAINFALL , *BIOMASS , *SPATIO-temporal variation , *FACTOR structure , *SALINITY , *ESTUARIES , *FISHING nets - Abstract
In this study, the relationship between fish assemblage structure and environmental factors was analyzed in a bay in southern Brazil. Fish were collected every two months between February and December 2002 at six sampling sites using bottom trawl nets. Abiotic data (salinity, temperature, rainfall, and depth) and biotic data (number of individuals, biomass, and total length of individuals from each species) were obtained. In total, 56 fish species representing 27 families were collected. Assemblage structure varied with seasonality, as was evidenced by the variation in temperature and rainfall in each season. Catches showed a high abundance of demersal fishes, particularly Genidens genidens, Eucinostomus gula, and E. argenteus. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
35. Sexual dimorphism in age, growth and sexual maturity in channel bull blenny Cottoperca trigloides (Forster, 1801) (Bovichtidae: Notothenioidei) on the Patagonian Shelf, Southwest Atlantic.
- Author
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Arkhipkin, Alexander, Shcherbich, Zhanna, Busbridge, Thomas, Blake, Alex, and Lee, Brendon
- Subjects
SEXUAL dimorphism ,LIFE history theory ,MARINE zooplankton ,SIZE of fishes ,BULLS - Abstract
Perciform fish of the suborder Notothenioidei radiated in the cold marine environments of the Southern Ocean around Antarctica where they evolved a diverse array of ecological forms. Despite their relatively high abundance and important roles in the Antarctic and sub-Antarctic ecosystems, many aspects of their life history are still poorly known. In the present study, age, growth and sexual maturity of channel bull blenny Cottoperca trigloides were analysed using the data of 28,229 specimens collected over the last 30 years in the southern part of the Patagonian Shelf in the Southwest Atlantic. It was found that C. trigloides features sexual dimorphism with males attaining larger sizes than females, an unusual characteristic for notothenioid fish. Males also had higher growth rates, older maximum ages and slower maturation. The peak in gonad maturation and spawning in C. trigloides was revealed to take place in austral winter, similar to other notothenioids from the Patagonian Shelf, thus matching larval hatch with the spring bloom of zooplankton. Sexual dimorphism may be advantageous for large territorial males during competitive interactions, particularly in an environment characterised by strong patchiness of rocky areas that are most suitable for spawning. Evolution of life history traits that placed C. trigloides close to the r-end within the r/K strategy continuum evolved by notothenioid fishes, enabled this species to successfully compete with other medium-large and large predators in resources-rich environment of the Patagonian Shelf. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
36. Insights into glacial terminations from a South Atlantic perspective
- Author
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Roberts, Jenny, Hodell, David A., and Peck, Vicky L.
- Subjects
551.31 ,Antarctic Intermediate Water ,Southwest Atlantic ,Paleoceanography - Abstract
The last two glacial terminations represent the most recent, and best documented, periods of Earth warming in the geological record. During these terminations atmospheric CO\textsubscript{2 }rose by approximately 100 ppm and global mean temperatures increased by 4-6\textsuperscript{o}C. Whilst the driver for these deglaciations ultimately derives from changes in the insolation forcing at the edge of the atmosphere, feedbacks within the Earth\textquoteright s climate system act to amplify these small external forcings tipping the Earth from a cold glacial climate state to a warm interglacial climate state. A key question in Quaternary climate science is understanding which feedbacks are important in regulating global climate on glacial-interglacial timescales. On this topic, the Southern Ocean has long been considered to be an important player in regulating atmospheric CO\textsubscript{2 } on glacial-interglacial timescales. This thesis investigates some of the hypothesised drivers of changes in atmospheric CO\textsubscript{2 } on glacial-interglacial timescales by generating high-resolution multi-proxy records from the Southern Ocean spanning the last two glacial terminations. In particular, I focus on changes in the structure, circulation and biological productivity within the sub-Antarctic zone. A change in the deep ocean density structure has been hypothesised to have resulted in the release of CO\textsubscript{2 } from the deep ocean. Centennial records from the sub-Antarctic are used to reconstruct deep and intermediate water density for the first time. I demonstrate that timing of the major breakdown in the density gradient of the ocean significantly lagged the breakdown in the chemical gradient, suggesting that changes in the deep ocean density structure were not the major driver of the deglacial rise in atmospheric CO\textsubscript{2 }. Changes in the density structure of the Southern Ocean likely had significant implications for global circulation. In particular, the flow of low salinity water through the Drake Passage is thought to be important in setting the strength and geometry of Atlantic Overturning Circulation. Drake Passage through-flow speed was reconstructed from two sites in the central and northern margins of the Antarctic Circumpolar Current downstream of Drake Passage. These records suggest a very different structure of Antarctic Circumpolar flow through Drake Passage during glacial periods, and evidence significant changes in ocean temperature as a result of pronounced reductions in Drake Passage through-flow. The strength of the biological pump has long been identified as an important player in regulating atmospheric CO\textsubscript{2 }. In particular, a strong glacial increase in sub-Antarctic productivity has been observed at open ocean sites in the South Atlantic and Indian Ocean. However, the glacial-interglacial changes in productivity in sub-Antarctic shelf settings are less well-documented. The new high-resolution records presented here from the sub-Antarctic southwest Atlantic suggest a significant change in the CaCO\textsubscript{3}:C\textsubscript{org} ratio which likely has implications for the surface ocean\textquoteright s ability to uptake CO\textsubscript{2 }.
- Published
- 2016
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- View/download PDF
37. Growth estimates of young‐of‐the‐year broadnose sevengill shark, Notorynchus cepedianus, a top predator with poorly calcified vertebrae.
- Author
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Jaureguizar, Andrés Javier, Cortés, Federico, Braccini, J. Matias, Wiff, Rodrigo, and Milessi, Andrés C.
- Subjects
- *
TOP predators , *BIRTH size , *VERTEBRAE , *WILDLIFE conservation , *SHARKS , *HABITATS , *PREDATION - Abstract
The broadnose sevengill shark, Notorynchus cepedianus (Péron, 1807), is a large marine top predator in temperate coastal ecosystems. Some aspects of its life history have been determined, but its growth pattern is yet to be fully understood. The authors used a multi‐modelling approach and a sensitivity test to estimate growth parameters from young‐of‐year (YOY) length data collected off San Antonio Cape (SAC), Argentina, a critical habitat in the Southwest Atlantic Coastal Zone (SACZ). The best selected model, a sex‐combined logistic growth model, estimated an asymptotic length (L∞) of 92.58 cm TL (95% C.I.: 86.48–105.89 cm), a growth coefficient (K) of 0.006818 days −1 (95% C.I.: 0.004948–0.008777) and a size at birth (L0) of 40.73 cm. The predicted annual growth (i.e., L1 –L0) was 43.2 cm TL. Males had smaller L0, higher K and achieved larger sizes after 1 year. The YOY in SAC attained a larger L1 and grew faster than their Australian and South African wild counterparts. The consistent year‐round presence of YOY in the SAC highlights the importance of this area as a pupping ground and potential nursery for N. cepedianus; this has direct implications for the allocation of research and management effort for the conservation of this species in the Southwest Atlantic. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
38. Chondrichthyans from the southern tip of South America with emphasis on the marine protected area Namuncurá-Burdwood Bank: exploring egg nursery grounds
- Author
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Matusevich, Florencia, Vazquez, Diego Martín, Gabbanelli, Valeria, Díaz de Astarloa, Juan Martín, and Mabragaña, Ezequiel
- Published
- 2023
- Full Text
- View/download PDF
39. Spectral Indexing of MODIS-Image Pixels to Reveal the Variability in the Phytopigment Composition in the Sea under the Influence of Mesoscale Water Dynamics.
- Author
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Karabashev, G. S.
- Subjects
- *
PIXELS , *OCEAN color , *PLANT pigments , *ELECTRONIC data processing , *CONTINENTAL slopes , *OCEAN - Abstract
A method is proposed for visualizing the inconstancy of the phytopigment composition in the water layer of the formation of backscattered solar radiation recorded by the MODIS multispectral ocean color scanner. The method relies on the fact that each pixel of the MODIS raster image of the investigated water area is assigned a wavelength reflectance minimum (WRM) index. The latter is equal to the sum of the wavelengths of minimums in the spectrum of a pixel or index 100 if they are absent. Such minimums are possible only in the presence of phytoplankton as the only carrier of plant pigments in the open sea. Pixel attributes of a MODIS raster image of the surface of water, like pixel coordinates and standard medium definitions, serve as WRM estimates. This makes it possible to visualize the variability of manifestations of the spectral diversity of phytoplankton against the background of the variability of the given medium properties. The effectiveness of the method is tested using the example of MODIS images of a spiral-eddy structure in the Caspian Sea and mesoscale variability of the bio-optical characteristics of waters over the continental slope in the Southwest Atlantic. The spectral indexing of the pixels of MODIS images of the water surface makes it possible to reveal some forms of variability of phytopigments of the aquatic environment that are inaccessible to the standard methods of ocean-color data processing. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
40. An unusual symbiotic relationship between a cyclostome bryozoan and a thecate hydroid.
- Author
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López-Gappa, Juan and Liuzzi, María G.
- Abstract
Previous examples of symbiotic associations between bryozoans and hydrozoans mainly involve cheilostome bryozoans and athecate hydroids belonging to the Family Zancleidae, in which only the hydrorhizal stolons become covered by a calcareous layer secreted by the bryozoan. The aim of this study is to describe an unusual symbiotic relationship between the cyclostome bryozoan Disporella densiporoides and the stolonal thecate hydroid Filellum bouvetensis (Family Lafoeidae) from Isla de los Estados, Southwest Atlantic. We found more than 120 chimney-like calcareous tubes covering most of the hydrozoan symbiont produced by only one bryozoan colony. Similar chimney-like tubes built by other cyclostome bryozoans have been attributed to the association with sedentary polychaetes or mistakenly interpreted as an ooeciostome, i.e. the aperture of a bryozoan reproductive polymorph. This is the first example of a symbiotic relationship in which most of the hydrozoan colony becomes covered by the bryozoan skeleton. The brood-chamber of D. densiporoides, previously unknown, is described and illustrated. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
41. First documented records of white-faced storm-petrel Pelagodroma marina for Uruguay
- Author
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Muñoz, Joaquín, Frones, Lucía, Castelli, Diego, and Jiménez, Sebastián
- Published
- 2023
- Full Text
- View/download PDF
42. Marine fish imported from Argentina as source of human diphyllobothriosis in Europe? Ecological evidence from dolphins.
- Author
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Hernández‐Orts, Jesús S., Scholz, Tomáš, Loizaga, Rocío, García, Néstor A., Crespo, Enrique A., and Kuchta, Roman
- Subjects
- *
MARINE fishes , *GASTROINTESTINAL contents , *PARASITIC diseases , *REPORTING of diseases , *IMPORTS , *BOTTLENOSE dolphin , *DOLPHINS - Abstract
Diphyllobothriosis caused by the Pacific broad tapeworm Adenocephalus pacificus (syn. Diphyllobothrium pacificum) is an emerging parasitic disease reported also from non‐endemic areas, including Europe (Spain). The origin of these human cases is unknown but should be related to fresh marine fish imported from endemic areas. In this study, we molecularly confirmed common dolphins Delphinus delphis off Argentina as euparatenic transit hosts of A. pacificus. Preliminary analysis of their stomach content, together with data from previous studies from the Southwest Atlantic, showed that common dolphins feed almost exclusively on schooling Argentine hake Merluccius hubbsi and Argentine anchovy Engraulis anchoita. Therefore, we suggest that Argentine hake and Argentine anchovy may represent the intermediate hosts of A. pacificus in the Southwest Atlantic, but also in Europe to where M. hubbsi is imported on ice (unfrozen). [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
43. Ecological Role of Common Appendicularian Species from Shelf Waters Off Argentina
- Author
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Capitanio, Fabiana L., Spinelli, Mariela L., Presta, María L., Aguirre, Gastón E., Cervetto, Guillermo, Pájaro, Marcelo, Derisio, Carla M., Hoffmeyer, Mónica S., editor, Sabatini, Marina E., editor, Brandini, Frederico P., editor, Calliari, Danilo L., editor, and Santinelli, Norma H., editor
- Published
- 2018
- Full Text
- View/download PDF
44. Perspective: Continental Inputs of Matter into Planktonic Ecosystems of the Argentinean Continental Shelf—the Case of Atmospheric Dust
- Author
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Crespi-Abril, Augusto C., Barbieri, Elena S., Villalobos, Leilén Gracia, Soria, Gaspar, Paparazzo, Flavio E., Paczkowska, Joanna M., Gonçalves, Rodrigo J., Hoffmeyer, Mónica S., editor, Sabatini, Marina E., editor, Brandini, Frederico P., editor, Calliari, Danilo L., editor, and Santinelli, Norma H., editor
- Published
- 2018
- Full Text
- View/download PDF
45. Trophic relationships and use of area of two sympatric small cetaceans in the Southwestern Atlantic Ocean determined by carbon and nitrogen stable isotopes
- Author
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LAURA B. CAMPOS and MARCOS CÉSAR DE O. SANTOS
- Subjects
isotopic niche ,Pontoporia blainvillei ,Sotalia guianensis ,Southwest Atlantic ,stable isotopes ,use of area ,Science - Abstract
Abstract As cetaceans are sentinels of the marine environment, studying their life history is of utmost importance in understanding their habits and their interaction with the environment. To achieve this goal, it is important to study their ecological niches through the investigation of their habitat use patterns and trophic relationships. This study aimed to evaluate if there are differences in the habitat use patterns and the trophic ecology of franciscana (Pontoporia blainvillei) and Guiana dolphins (Sotalia guianensis) accidentally caught off the south coast of São Paulo State, and Guiana dolphins biopsied in the Cananeia estuary, southeastern Brazil, based on the carbon and the nitrogen stable isotopes analysis. Isotopic ratios were estimated from skin samples. The isotopic niche size and overlap were calculated using the SIBER package (R software). The gathered results showed evidence of spatial segregation between Guiana dolphins and franciscanas. The Guiana dolphins sampled inside and outside the estuary showed evidence of trophic and spatial segregation. No difference in isotopic values between sexes was found for both species. Such differences between franciscanas and Guiana dolphins were expected as both species have distinct life histories as a result of different evolutionary pathways.
- Published
- 2021
- Full Text
- View/download PDF
46. 阿根廷滑柔鱼年间生长及体征变化.
- Author
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臧 娜, 连晋欣, 陈新军, and 林东明
- Abstract
Copyright of Journal of Hydrobiology / Shuisheng Shengwu Xuebao is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2021
- Full Text
- View/download PDF
47. First report of the hapuku wreckfish Polyprion oxygeneios (Polyprionidae) in Argentinian waters.
- Author
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Milessi, Andrés C., De Wysiecki, Agustín M., Carvalho Filho, Alfredo, and Wiff, Rodrigo
- Subjects
- *
SPECIES distribution , *SPECIES , *FISHERS , *GROUPERS - Abstract
The hapuku wreckfish Polyprion oxygeneios is recorded for the first time in Argentinian waters. Four specimens were caught off Mar del Plata (38°S, Argentina) in depths between 60 and 260 m during austral summer (three by sport fishers and one in a research cruise). Up to the present, this species was consistently misidentified with its congener, the common wreckfish P. americanus, off Argentina. These records represent a connection between previous records from Brazil and the more austral circumglobal distribution of the species. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
48. Using BRUVS to describe the fish assemblage and its seasonality in two shallow marine inlets within protected areas of Patagonia, Argentina
- Author
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Gastón Trobbiani, Agustin M. De Wysiecki, Nelson Bovcon, and Alejo J. Irigoyen
- Subjects
fish monitoring ,marine protected areas ,Southwest Atlantic ,video imagery ,Environmental sciences ,GE1-350 ,Ecology ,QH540-549.5 - Abstract
Baited Remote Underwater Video Stations (BRUVS) complemented with fishing methods were used to describe the fish assemblage and its seasonal pattern in two marine inlets from Patagonia. The combined results for BRUVS and fishing sessions identified 13 fish species. Our results agree with the biogeographic schemes proposed for the southern Southwest Atlantic. The fish species belonging to the Argentine Biogeographic Province presented a seasonal pattern with a peak of maximum abundance (Notorynchus cepedianus and Galeorhinus galeus) or were recorded during warm months only (Mustelus schmitti, Myliobatis goodei, and M. ridens), coinciding with the general latitudinal pattern expected for fish species richness. The use of BRUVS in this study allowed for the assessment of different fish species and wide range of sizes, from large sharks (N. cepedianus) to small cryptic species (Patagonotothem sp.). However, three of 13 species were only recorded by fishing methods, like it was the case for M. ridens. The record of M. ridens is the first in Patagonian waters, extending its distribution for c. 180 km south of the previously known southern limit. This study contributes to filling large data gaps along the Southwest Atlantic regarding the description and understanding of the temporal dynamics of fish assemblages in particular environments within protected areas.
- Published
- 2021
- Full Text
- View/download PDF
49. Haplotype networks of Phycocalidia tanegashimensis (Bangiales, Rhodophyta) indicate a probable invasion from the South China Sea to Brazil.
- Author
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Zhao, Wan, Dong, Lei, Hong, Dang Diem, Brodie, Juliet, Chen, Wei-Zhou, Tien, Dam Duc, Zhou, Wei, Lu, Qin-Qin, Zhang, Mei-Ru, and Yang, Li-En
- Abstract
Invasive species of intertidal algae drew little attention, even though biological invasions have been a concern around the world. The red algal bangiophyte, Phycocalidia tanegashimensis (I. Shinmura) Santiañez in Santiañez & Wynne, 2020 had been reported from the Southwest Atlantic (Brazil) and Northwest Pacific (Philippines and Japan). The appearance of P. tanegashimensis in Brazil was believed to be a recent introduction from the Indo-Pacific/North Pacific but without conclusive evidence. During a study of the biodiversity of bladed Bangiales in South China and Vietnam, we detected the presence of P. tanegashimensis in these areas using a molecular approach to the identification of the species. New distributional records of P. tanegashimensis were therefore morphologically and molecularly confirmed along the Chinese and Vietnamese coastline (part of the South China Sea) in the present study. Molecular sequence data using rbcL (ribulose bisphosphate carboxylase/oxygenase large subunit), COI-5P (cytochrome oxidase 1), and 18S rRNA genes placed P. tanegashimensis in a clade with P. acanthophora (E.C.Oliveira & Coll) Santiañez in Santiañez & Wynne, 2020, P. denticulata (Levring) Santiañez & M.J.Wynne, 2020, P. suborbiculata (Kjellman) Santiañez & M.J.Wynne, 2020 and P. vietnamensis (Tak.Tanaka & Pham) Santiañez & M.J.Wynne, 2020 as out-groups. The common morphological characters found in these species, including lobed blades and marginal denticulation, and subtropical/tropical distribution, were discussed in relation to their phylogeny. Haplotype distribution analysis indicated that P. tanegashimensis in Brazil might be an invasive species from the South China Sea. The arrival time of P. tanegashimensis from the South China Sea to Brazil was also discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
50. Using BRUVS to describe the fish assemblage and its seasonality in two shallow marine inlets within protected areas of Patagonia, Argentina.
- Author
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TROBBIANI, GASTÓN, DE WYSIECKI, AGUSTÍN M., BOVCON, NELSON D., and IRIGOYEN, ALEJO J.
- Subjects
GALEORHINUS galeus ,MUSTELUS schmitti - Abstract
Copyright of Ecologia Austral is the property of Asociacion Argentina de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2021
- Full Text
- View/download PDF
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