Vibrational spectroscopy coupled to a multivariate analysis tiered approach for argentinean honey provenance confirmation

In the present work, the provenance discrimination of Argentinian honeys was used as case study to compare the capabilities of three spectroscopic techniques as fast screening platforms for honey authentication purposes. Multifloral honeys were collected among three main honey-producing regions of Argentina over four harvesting seasons. Each sample was fingerprinted by FT-MIR, NIR and FT-Raman spectroscopy. The spectroscopic platforms were compared on the basis of the classification performance achieved under a supervised chemometric approach. Furthermore, low- mid- and high-level data fusion were attempted in order to enhance the classification results. Finally, the best-performing solution underwent to SIMCA modelling with the purpose of reproducing a food authentication scenario. All the developed classification models underwent to a “year-by-year” validation strategy, enabling a sound assessment of their long-term robustness and excluding any issue of model overfitting. Excellent classification scores were achieved by all the technologies and nearly perfect classification was provided by FT-MIR. All the data fusion strategies provided satisfying outcomes, with the mid- and high-level approaches outperforming the low-level data fusion. However, no significant advantage over the FT-MIR alone was obtained. SIMCA modelling of FT-MIR data produced highly sensitive and specific models and an overall prediction ability improvement was achieved when more harvesting seasons were used for the model calibration (86.7% sensitivity and 91.1% specificity). The results obtained in the present work suggested the major potential of FT-MIR for fingerprinting-based honey authentication and demonstrated that accuracy levels that may be commercially useful can be reached. On the other hand, the combination of multiple vibrational spectroscopic fingerprints represents a choice that should be carefully evaluated from a cost/benefit standpoint within the industrial context

Embryonic mortality due to cannibalism in the Argentine anchovy Engraulis anchoita Hubbs and Marini, 1935

The Argentine anchovy Engraulis anchoita Hubbs and Marini, 1935, is, in terms of biomass, the greatest fish resource in the Southwest Atlantic. It plays a key role in the Argentine fisheries as trophic support for several commercially exploited species. Argentine anchovy migrate to their coastal spawning grounds during spring and summer; and at least two populations co-exist in the spawning- area: the northern, or Buenos Aires, population (from 33° LS to -41° LS) and the southern, or Patagonian, population (from 41° LS to -48° LS). From a trophic standpoint, this a poor habitat for such a large number of anchovies, and copepods predominate amont their prey organisms to findings from our analysis of stomach contents. No relationship was found between consumption and density of plankton eggs; however, in the northern population, there was evidence of an increase in cannibalism as mezooplancton density decreased. Regarding the number of eggs ingested, we estimated a mean value of 10.0 eggs/fish (standard desviation: 5.04) and 0.8 (s.d.: 0.44) eggs/fish (s.d.e.: = 0.44) for the Buenos Aires and Patagonian populations, respectively. The mean number of anchovy eggs per stomach was 14.1 (s.d. 7.9) for nocturnal samples and 1.0 (s.d.: 0.4) for daytime samples. Consumption of eggs over a 12 h feeding period was estimated to have caused 27 % of the total eggs mortality for the Buenos Aires stock and 1-2 % for the Patagonian stock. Our results indicate that intraespecific predation on eggs by anchovy adults represents a high percentage of the total embryonic mortality, especially in areas where other food resources are scarce.La anchoíta argentina Engraulis anchoita Hubbs y Marini, 1935, el recurso pesquero de mayor biomasa del Atlántico sudoccidental, constituye una especie clave en el ecosistema pesquero del Mar Argentino como alimento de varias especies explotadas comercialmente. La anchoíta migra al hábitat costero en primavera, donde se lleva a cabo la puesta. Dos poblaciones, al menos, habitan el área reproductiva en esa época del año: la población bonaerense (33°-41° S) Y la población patagónica (41°-48° S). Desde el punto de vista trófico, dicho hábitat es pobre para los numerosos cardúmenes de anchoíta, con predominio de los copépodos entre los organismos presa, observación que también puso de manifiesto el análisis de los contenidos estomacales. No se encontró una relación entre el número de huevos consumidos y la densidad de huevos en el plancton, aunque sí se hallaron, en la población bonaerense, evidencias del aumento del canibalismo junto con la disminución en la densidad de mesozooplancton. En cuanto al número de huevos ingeridos por canibalismo, se determinaron valores medios de 10,0 (desviación estándar: 5,04) y 0,8 huevos/pez (d. e.: 0,44) para las poblaciones bonaerense y patagónica respectivamente. Por otra parte el canibalismo se produjo principalmente en horas diurnas, con. 14,1 huevos/pez (d. e.: 7,9) frente a 1,0 (d.e.: 0,4) para las horas nocturnas. La mortalidad embrionaria natural diaria por canibalismo, considerando un periodo de alimentación de 12 horas, fue de 27 % para la población bonaerense y de 1-2 % para la población patagónica. Los resultados obtenidos permiten concluir que la depredación intraespecífica sobre los estadios embrionarios de la anchoíta argentina puede llegar a representar un porcentaje importante de la mortalidad natural embrionaria total, especialmente en zonas con escaso alimento disponible.Instituto Español de Oceanografí

Fecundity estimates of the Argentine red shrimp Pleoticus muelleri Bate, 1888 off Patagonia (southern Argentina)

Fecundity o/the Argentine red shrimp Pleoticus muelleri Bate, 1888 was estimated stereologically, and its relationship to carapace length and body weight was analysed. Samples from the spawning grounds located in the southern Gull of San Jorge (Southwest Atlantic, 47° S) collected during the peak and at the end of the spawning season were also compared. Moreover, a sample of large females obtained near the city of Rawson (43° 20' S) was included. Observations of the ovocyte diameter distributions showed the existence of two main generations of ovocytes before spawning (undeveloped and ripe). Potential fecundity, defined as the number of yolked ovocytes, ranged from 72 000 to 1 000 000 ova for females with a carapace length of 25 to 55 mm. The relationships fecundity vs body weight and fecundity vs carapace length estimated for females collected in the Gulf of San Jorge and off Rawson showed a better fit to the power model. Mean relative fecundity was 10 444 ovocytes/g body weight (s = 2 150). Production of eggs was found to decrease significantly by the end of the spawning, season, both in terms of lower individual fecundity and of the increase in atretic processes (20 % o/ ripe ovaries with ova undergoing resorption).En el presente estudio, se estima la fecundidad del langostino argentino Pleoticus muelleri Bate, 1888 y se analiza la relación de esta variable con la talla y el peso de los individuos. Se comparan los valores de fecundidad hallados en el sur del golfo San Jorge (Atlántico sudoccidental, 47° S) durante el periodo de máxima actividad reproductiva (enero) y al final de la temporada de puesta (marzo). Estos resultados se complementan con otras estimaciones de fecundidad realizadas con ejemplares de gran tamaño capturados en las cercanías de la ciudad de Rawson (43° 20' S). El análisis histológico de los ovarios maduros y la distribución de diámetros ovocitarios pusieron en evidencia la existencia de dos generaciones ovocitarias principales en el momento previo al desove (los elementos previtelogenéticos y los vitelados). La fecundidad potencial (número de ovocitos vitelados) varió entre 72 000 Y 1 000 000 para un rango de tallas entre 25 y 55 mm de longitud de caparazón. Las relaciones entre la fecundidad y las variables talla y peso se ajustaron al modelo potencial, tanto para los ejemplares de la zona del golfo San Jorge como para los de Rawson. La fecundidad relativa media para los datos agrupados de estas dos áreas durante el pico de actividad reproductiva fue 10 444 (s = 2 150) ovocitos por gramo de hembra. Se observó una marcada disminución en la producción de huevos de los ejemplares del golfo San Jorge al final de la estación de puesta (marzo). Esta diferencia se vio reflejada en el incremento de las atresias, observándose durante marzo el 20 % de los ovarios, aproximadamente, con reabsorción generalizada de ovocitos.Instituto Español de Oceanografí

Summer distribution, abundance and population structure of illex argentines on the argentine shelf in relation to environmental features

The distribution, abundance and population structure of Illex argentinus in relation to oceanographic conditions during summer 1996 were analysed following a research cruise to the Argentine shelf (39°–51°30´S). Squid were distributed over the whole area, but the main concentrations were on the intermediate and outer Patagonian shelf (44°30´–47°30´S), where there was a thermal front (12–15°C). Three squid groups were detected through study of the distributional area, size, maturity stage, age and hatching month. North of 41°S, there were immature individualsof 14–21 cm mantle length (ML) that had hatched mostly in June. Small mature, spawning and spent squid (males 14–22 cm ML, females 18–26 cm ML) were found on the inner and intermediate shelf between 40°30´ and 46°30´S. They had hatched from January to April, with a clear peak in March. South of 45°S, males of 17–25 cm ML and females of 17–29 cm ML were found over the intermediate and outer shelf; most males were mature whereas the majority of the females were immature. They had hatched from May to July, with a peak in June. The relationship between statolith increment and size showed that the growth rates of the later-hatched individuals were faster than those of individuals hatched earlier. The squid preyed almost exclusively on zooplankton (87%), mostly the hyperiid amphipod Themisto gaudichaudii (79%)

Merluccius hubbsi (Teleostei: Merlucciidae): stock identification based on reproductive biology in the south-southeast brazilian region

The Argentine hake, Merluccius hubbsi, a demersal-pelagic species found from Rio de Janeiro, Brazil to the Tierra del Fuego, Argentina, has become an important target of the Brazilian bottom-trawler fleet since 2001. Earlier studies focusing on the species have suggested that more than one stock might occur off the Brazilian coast, in accordance with environmental features. In order to evaluate this hypothesis, fish were collected from four different areas in the Brazilian waters in which the hake is distributed, during the summers and winters of 1996-2001 and 2004, the females being used to analyze and compare spatial-temporal variations in ovarian maturation. Gonad indexes were also applied for the same purpose. Results indicate a north-south spawning gradient occurring as from summer at around 21°S to winter near 34°S, leading to the identification of two distinct stocks: one located between 21°S and 29°S (Southeastern stock) and the other between 29°S and 34°S (Southern stock), this latter shared with Uruguay and Argentina. Brazilian stocks present clear signs of overexploitation, the situation calling for an urgent solution.<br>A merluza Merluccius hubbsi, espécie demerso-pelágica distribuída desde o Rio de Janeiro, Brasil, até a Terra do Fogo, Argentina, tornou-se alvo das frotas de arrasto de fundo da região Sudeste-Sul do Brasil desde 2001. Estudos anteriores sobre a biologia da espécie sugeriram a existência de mais de um estoque em águas brasileiras, relacionados a características ambientais. Para verificar esta hipótese, exemplares oriundos de quatro áreas em águas brasileiras foram coletados durante o verão e o inverno nos períodos 1996-2001 e 2004, sendo as fêmeas utilizadas para analisar variações espaço-temporais na maturação gonadal. Para corroborar estas análises também foram aplicados índices gonadais. Os resultados mostraram a ocorrência de um gradiente norte-sul para a desova, que é mais intenso no verão em 21°S e no inverno em 34°S. Foram identificados dois estoques: um denominado Sudeste, que se distribui entre 21°S-29°S, e outro Sul, entre 29°S-34°S, este último compartilhado com o Uruguai e a Argentina. Os estoques brasileiros apresentam sinais de sobrepesca, situação que merece atenção e medidas apropriadas de gestão