Trophic niche partitioning of five skate species of genus Bathyraja in northern and central Patagonia, Argentina

Overexploitation of marine communities can lead to modifications in the structure of the food web and can force organisms like elasmobranchs to change their feeding habits. To evaluate the impact that fisheries have on food webs and on the interactions between species, it is necessary to describe and quantify the diet of the species involved and follow it through time. This study compares the diet of five skate species using the data obtained from the by-catch of the Argentine hake (Merluccius hubbsi) fishery in north and central Patagonia, Argentina. Diet composition was assessed by analysing the digestive tract contents and trophic overlapping between species of the genus Bathyraja: Bathyraja albomaculata, Bathyraja brachyurops, Bathyraja macloviana, Bathyraja magellanica and Bathyraja multispinis. A total of 184 stomachs were analysed. The diets of B. albomaculata and B. macloviana mainly comprised annelids, whereas that of B. brachyurops primarily comprised fish, including hake heads discarded by the fishery. The diets of B. magellanica and B. multispinis were largely based on crustaceans. Despite the morphological similarities and their shared preference for benthic habitats, no complete diet overlaps were found between the different species. These results suggest that these skate species have undergone a process of diet specialisation. This is a common feeding strategy that occurs to successfully eliminate competition when resources are limited, which corresponds to the conditions found in an environment being affected by the pressures of overfishing.Fil: Tschopp, Ayelen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Cristiani, Franco. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales y Ciencias de la Salud - Sede Puerto Madryn. Departamento de Biología y Ambiente; ArgentinaFil: Garcia, Nestor Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Crespo, Enrique Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales y Ciencias de la Salud - Sede Puerto Madryn. Departamento de Biología y Ambiente; ArgentinaFil: Coscarella, Mariano Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales y Ciencias de la Salud - Sede Puerto Madryn. Departamento de Biología y Ambiente; Argentin

Development of a site fidelity index based on population capture-recapture data

Background Site fidelity is considered as an animal’s tendency to return to a previously occupied place; this is a component of animal behaviour that allows us to understand movement patterns and aspects related to the animal’s life history. Although there are many site fidelity metrics, the lack of standardisation presents a considerable challenge in terms of comparability among studies. Methods This investigation focused on the theoretical development of a standardised composite site fidelity index and its statistical distribution in order to obtain reliable population-level site fidelity comparisons. The arithmetic and harmonic means were used as mathematical structures in order to create different indexes by combining the most commonly used indicators for site fidelity such as Occurrence, Permanence and Periodicity. The index performance was then evaluated in simulated populations and one real population of Commerson’s dolphins (Cephalorhynchus commersonii (Lacépède 1804)). In the first case, the indexes were evaluated based on how they were affected by different probability values such as the occurrence of the individual within the study area (φ) and capture probability (p). As a precision measure for the comparison of the indexes, the Wald confidence interval (CI) and the mean square error were applied. Given that there was no previous data concerning the distribution parameters of this population, bootstrap CIs were applied for the study case. Results Eight alternative indexes were developed. The indexes with an arithmetic mean structure, in general, had a consistently inferior performance than those with a harmonic mean structure. The index IH4, in particular, achieved the best results in all of the scenarios and in the study case. Additionally, this index presented a normal distribution. As such, it was proposed as a standardised measure for site fidelity (Standardised Site Fidelity Index—SSFI). Discussion The SSFI is the first standardised metric that quantifies site fidelity at a populational level. It is an estimator that varies between zero and one and works in situations where detection is not perfect and effort can be constant or not. Moreover, it has an associated CI that allows users to make comparisons

Cambios en la composición de la dieta de la raya hocicuda de cola corta Zearaja brevicaudata (Marini, 1993) en el ecosistema explotado de Patagonia, Argentina

La raya hocicuda de cola corta Z. brevicaudata1 es capturada incidentalmente por la pesquería de merluza común (Merluccius hubbsi), en aguas del norte y centro del Mar Argentino en Patagonia. El colapso de esta pesquería en la plataforma patagónica durante la década del 90´ y su posterior estabilización en niveles de explotación menores puede haber producido cambios en la estructura de la comunidad. Debido a que Z. brevicaudata es un predador tope de hábitos generalistas, es posible suponer que la composición de su dieta refleje los cambios ocurridos en el medio ambiente marino como resultado de los efectos de sobrepesca en el litoral patagónico. El objetivo de este trabajo es estudiar la tendencia de cambio en la composición de la dieta de Z. brevicaudata a lo largo del tiempo. Se utilizaron regresiones logísticas multinomiales implementadas en R para estudiar la composición de la dieta, en función de la talla del predador (85cm) y su período de captura (1996- 98,2000-01 y 2011). Se utilizaron presas con IRI%>15 (Acanthoserolis schythei, anfípodo gammaridae, descarte de M. hubbsi, Illex argentinus, M. hubbsi, Patagonotothen ramsayi, Peltarion spinosulum) obtenidas de contenidos estomacales de individuos apturados (n=541) incidentalmente por la pesquería de merluza común, en el norte y centro de Patagonia (41°S-48°S). El mejor modelo (AICc) incluyó el efecto multiplicativo de ambos factores periodo*talla. Durante el primer período, la presa predominante en la dieta fue M. hubbsi. Sin embargo, la composición de la dieta cambió a lo largo del tiempo para todos los rangos de talla observándose un aumento en el consumo tanto del descarte de M. hubbsi como de P. ramsayi, respecto a las demás presas. Los resultados mostraron que Z. brevicaudata podría estar reemplazando M. hubbsi, su principal presa, por otros recursos disponibles. Esto, podría ser consecuencia de la sobreexplotación pesquera, la cual podría estar cambiando la disponibilidad de M. hubbsi, modificando la composición de los ensambles de especies, provocando un impacto sobre la comunidad marina.Fil: Tschopp, Ayelen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Herrera, Valeria Paula. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Puerto Madryn. Instituto Patagónico del Mar; ArgentinaFil: Garcia, Nestor Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Crespo, Enrique Alberto. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Coscarella, Mariano Alberto. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaXVIII Congreso Latinoamericano de Ciencias del MarMar del PlataArgentinaAsociación Latinoamericana de Investigadores en Ciencias del Ma

Development of a site fidelity index based on population capture-recapture data

<p>Raw data supporting the results of the scientific article</p

Exposure to a Glyphosate-based Herbicide Alters the Expression of Key Regulators of Mammary Gland Development on Pre-pubertal Male Rats

We previously reported that exposure during gestation and lactation to a low dose of glyphosate-based herbicide(GBH) reduced the area and perimeter of male offspring mammary gland at postnatal day 60 (PND60), whereas ahigher dose increased the longitudinal growth of the gland. Here, our aim was to assess whether perinatalexposure to GBH exhibits endocrine disruptive action in male mammary gland at an early time point (prepuberty),which could be related to the changes observed after puberty. We also wanted to explore whether anearly evaluation of the male rat mammary gland is appropriate to assess exposure to potential endocrine disruptingchemicals (EDCs). Pregnant rats were orally exposed, through the diet, to vehicle (saline solution), 3.5 or350 mg/kg/day of GBH from gestational day 9 until weaning. At PND21, the male offspring were euthanized,and mammary gland samples were collected. The histology and proliferation index of the mammary glands wereevaluated, and the mRNA expression of estrogen (ESR1) and androgen (AR) receptors, cyclin D1 (Ccnd1),amphiregulin (Areg), insulin-like growth factor 1 (IGF1), epidermal growth factor receptor (EGFR) and IGF1receptor (IGF1R) were assessed. Moreover, the phosphorylated-Erk1/2 (p-ERK1/2) protein expression was determined.No differences were observed in mammary epithelial structures and AR expression between experimentalgroups; however, the proliferation index was reduced in GBH3.5-exposed males. This result was associatedwith decreased ESR1, Ccnd1, Areg, IGF1, EGFR and IGF1R mRNA expressions, as well as reduced p-Erk1/2 protein expression in these animals. ESR1, Ccnd1, IGF1R and EGFR expressions were also reduced in GBH350-exposed males. In conclusion, the mammary gland development of pre-pubertal male rats is affected by perinatalexposure to GBH. Although further studies are still needed to understand the molecular mechanisms involved inGBH350 exposure, the present results may explain the alterations observed in mammary gland growth of postpubertalmales exposed to low doses of GBH. Our results also suggest that early evaluation of the male ratmammary gland is useful in assessing exposure to potential EDCs. However, analysis of EDCs effects at later timepoints should not be excluded.Fil: Gomez, Ayelen Luciana. Cátedra de Patología Humana; ArgentinaFil: Altamirano, Gabriela Anahí. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Salud y Ambiente del Litoral. Universidad Nacional del Litoral. Instituto de Salud y Ambiente del Litoral; ArgentinaFil: Tschopp, María Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Salud y Ambiente del Litoral. Universidad Nacional del Litoral. Instituto de Salud y Ambiente del Litoral; ArgentinaFil: Bosquiazzo, Veronica Lis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Salud y Ambiente del Litoral. Universidad Nacional del Litoral. Instituto de Salud y Ambiente del Litoral; ArgentinaFil: Muñoz de Toro, Monica Milagros. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Salud y Ambiente del Litoral. Universidad Nacional del Litoral. Instituto de Salud y Ambiente del Litoral; ArgentinaFil: Kass, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Salud y Ambiente del Litoral. Universidad Nacional del Litoral. Instituto de Salud y Ambiente del Litoral; Argentin