Biología y ecología del calamar Dosidicus gigas (Cephalopoda) en aguas chilenas: una revisión

Indexación: Web of Science; Scielo.ABSTRACT. The jumbo squid Dosidicus gigas is the most abundant cephalopod species in the southeastern Pacific Ocean, which supports the biggest cephalopod fishery in the world. Due to its growing economic importance, the population growth and distributional expansion of this squid is being increasingly studied. Nevertheless, some basic features of the biology of D. gigas are still unknown or have been poorly investigated. In this review we summarize the known information regarding the biology and ecology of this species in the southeastern Pacific Ocean; we focus on the Chilean region in order to propose hypotheses and research lines for a better understanding the life history of this organism. Available data on the size structure, reproduction and genetics of D. gigas allows us to propose hypotheses related to the squid's life history traits. Based on the current literature and publications of colleagues, we propose two hypotheses regarding the effect of spatial variation on the life history of D. gigas. Hypothesis 1: Squids mature at large sizes and spawn in oceanic waters with warm temperatures where paralarvae and juveniles develop. Immature squids migrate near shore to feed, grow and mature, and then return to the offshore sites to spawn. Hypothesis 2: Alternatively, juvenile D. gigas in the oceanic zone do not migrate to coastal waters and mature at small sizes compared to individuals living near the coast that mature at larger size and migrate to oceanic waters to spawn. We provide background information about the feeding behavior and parasitism of this species, suggesting that D. gigas is an important trophic link in the southeastern Pacific marine ecosystem. However, more studies on the feeding habits, reproduction and parasite load are needed not only to test hypotheses proposed in this study, but also to advance the overall knowledge of this species.RESUMEN. Dosidicus gigas, es el calamar más abundante en el Pacífico suroriental, manteniendo la mayor pesquería mundial de cefalópodos. Su creciente importancia económica, ha motivado el aumento de estudios asociados al crecimiento de sus poblaciones y su expansión geográfica. Sin embargo, algunas características biológicas básicas de esta especie son desconocidas o escasamente estudiadas. En esta revisión, se resume la información sobre la biología y ecología de esta especie para el Pacífico suroriental y se proponen hipótesis y líneas de investigación para el mejor entendimiento de su historia de vida. Los datos sobre estructura de tamaños, reproducción y aspectos genéticos de la especie, permiten avanzar en las hipótesis relacionadas con la historia de vida de estos rasgos. Hipótesis 1: Los calamares maduran a gran tamaño y desovan en aguas oceánicas con temperaturas cálidas, donde paralarvas y juveniles se desarrollan. Los calamares inmaduros migran hacia la costa para alimentarse, crecer y madurar, y luego vuelven a los sitios en alta mar para desovar. Hipótesis 2: Alternativamente, los juveniles de D. gigas en la zona oceánica no migran a las aguas costeras y maduran pequeños en comparación a los individuos que viven cerca de la costa que maduran a un tamaño más grande y migran a las aguas oceánicas para desovar. Se proponen dos hipótesis acerca de la variación espacial de la historia de vida. Además, se proporciona el marco relativo a la alimentación y parasitismo del calamar, que coloca a D. gigas como un importante nexo trófico en los ecosistemas marinos del Pacífico suroriental. No obstante, se necesitan más estudios relacionados con alimentación, reproducción y carga parasitaria del calamar para poner a prueba las hipótesis propuestas en este trabajo.http://ref.scielo.org/hpft7

Variaciones estacionales en la estructura poblacional y condición reproductiva de la Jibia Dosidicus gigas (Orbigny, 1835) en Chile centro sur

In the area off central-south Chile (34-40ºS), a new period of high abundance of Dosidicus gigas has occurred since 2001. The seasonal changes in length structure and reproductive condition of D. gigas in oceanic and coastal waters are described for the period July 2003 to February 2004. The length structure varied significantly between seasons and zones. In the austral winter, medium-sized, maturing individuals were found in oceanic waters while large-sized mature males and maturing females were present in the coastal zone. In the austral spring, maturing medium-sized and large-sized individuals were observed in the oceanic zone. In contrast, two groups of individuals were observed in the coastal zone: one consisting of small and immature individuals, and one consisting of medium-sized maturing specimens. In the austral summer, only the oceanic zone was sampled, and samples contained small immature and maturing medium-sized individuals. We postulate that the spatial and temporal changes in length structure and reproductive condition of D. gigas off central-south Chile are probably due to the existence of a migratory strategy of the species in the study area.En el área de Chile central (34ºS-40ºS), un nuevo periodo de gran abundancia de Dosidicus gigas ha ocurrido desde al año 2001. En este trabajo, se describe los cambios en la estructura de tamaños y la actividad reproductiva de D. gigas en zonas oceánicas y costeras durante el periodo comprendido entre julio del año 2003 y febrero del año 2004. La estructura de tamaños de D. gigas varió significativamente entre estaciones y zonas. En invierno, encontramos un grupo de individuos de tamaño medio con una gran proporción de individuos en maduración en la zona oceánica. Otro grupo de individuos de gran tamaño estuvo presente en la zona costera con hembras en maduración y machos maduros. En primavera, la estructura de tamaños consistió de individuos en maduración medianos y grandes en la zona oceánica. En contraste, en la zona costera se observaron dos grupos de individuos: uno compuesto de individuos pequeños e inmaduros y otro grupo con individuos grandes y en maduración. En verano, sólo se obtuvieron muestras de la zona oceánica, que consistió en individuos pequeños inmaduros y ejemplares de tamaño medio en maduración. Este trabajo postula que la estructura de tamaños de D. gigas en Chile centro-sur se debe probablemente a la existencia de una estrategia migratoria de la especie en el área de estudio

Seasonal variation in the length structure and reproductive condition of the jumbo squid <i>Dosidicus gigas</i> (d’Orbigny, 1835) off central-south Chile

In the area off central-south Chile (34-40ºS), a new period of high abundance of Dosidicus gigas has occurred since 2001. The seasonal changes in length structure and reproductive condition of D. gigas in oceanic and coastal waters are described for the period July 2003 to February 2004. The length structure varied significantly between seasons and zones. In the austral winter, medium-sized, maturing individuals were found in oceanic waters while large-sized mature males and maturing females were present in the coastal zone. In the austral spring, maturing medium-sized and large-sized individuals were observed in the oceanic zone. In contrast, two groups of individuals were observed in the coastal zone: one consisting of small and immature individuals, and one consisting of medium-sized maturing specimens. In the austral summer, only the oceanic zone was sampled, and samples contained small immature and maturing medium-sized individuals. We postulate that the spatial and temporal changes in length structure and reproductive condition of D. gigas off central-south Chile are probably due to the existence of a migratory strategy of the species in the study area

Biases in determining the diet of jumbo squid Dosidicus gigas (D’ Orbigny 1835) (Cephalopoda: Ommastrephidae) off southern-central Chile (34°S–40°S)

The diet of jumbo squid (Dosidicus gigas) off southern-central Chile is described to examine potential biases in the determination of their main prey. Specimens were collected from catches using different fishing gear (jigging, trawl and purse-seine), from July 2003 to January 2004, and from December 2005 to October 2006. The stomach contents were analyzed in terms of frequency of occurrence, number, and weight of prey items and the diet composition was analyzed using Detrended Correspondence Analysis. In the industrial purse-seine fleet for jack mackerel (Trachurus murphyi), the dominant prey of D. gigas was T. murphyi. In the industrial mid-trawl fishery for Patagonian grenadier (Macruronus magellanicus), the dominant species in the diet of D. gigas was M. magellanicus. Similarly, Chilean hake (Merluccius gayi) was the main prey in the diet of D. gigas obtained in the industrial trawl fishery for Chilean hake; and, in both artisanal fisheries (purse-seine for small pelagics and jigging), small pelagic fish and D. gigas were the main prey in the stomach contents of D. gigas. Cannibalism in D. gigas varied between different fleets and probably is related to stress behavior during fishing. The Detrended Correspondence Analysis ordination showed that the main prey in the diet of D. gigas is associated with the target species of the respective fishery. Consequently, biases are associated with fishing gear, leading to an overestimate in the occurrence of the target species in the diet. We recommend analyzing samples from jigging taken at the same time and place where the trawl and purse-seine fleets are operating to avoid this problem, and the application of new tools like stable isotope, heavy metal, and fatty acid signature analyses

Dieta del pez espada Xiphias gladius Linnaeus, 1758, en aguas oceánicas de Chile central en invierno de 2003

The diet of swordfish is analyzed in three oceanic fishing zones off central Chile during winter 2003, testing the hypothesis that the body size of prey individuals significantly increases with the size of the predator, and that the number of prey individuals decreases with increase in their size. The study was based on 48 stomachs of Xiphias gladius found to contain identifiable prey remains. The analysis was made using quantitative descriptors of frequency and occurrence of prey items. Diets in the different sampling zones were ranked by frequency and occurrence of prey species. Also determined were the proportions of fishes and cephalopods in the diet, and number and sizes of cephalopods related to body lengths of the swordfish. Results of the study showed that the swordfish preyed primarily on squid, and secondarily on fishes. Dosidicus gigas was the main prey within two of the sampling zones (F=100 and 75%), and Onychoteuthis banksii in one zone (F = 71%). The number of prey individuals was not significantly related with the body length of X. gladius, but low correlation was noted between swordfish body size and prey size. The diet of X. gladius varied only according to the fishing zone, and was not related to the size of the predator. The habitat of the predator is one of the most important factors to be considered in the study of its' diet, since variation in the habitat may affect the population dynamics of both prey and predator

Evaluación sistemática del género Helcogrammoides (Blenniformes: Tripterygiidae): Pequeños peces con grandes problemas

La familia Tripterygiidae en las costas de Chile se encuentra representada por dos especies correspondientes al género Helcogrammoides; sin embargo, éstas fueron originalmente descritas en el género Tripterygion el cual se distribuye actualmente en el Mar Mediterráneo y en el noreste del océano Atlántico. En 1959, Rosenblatt reconoce las diferencias entre estas y las demás especies del género Tripterygion, proponiendo el género Helcogrammoides. En la actualidad la hipótesis taxonómica no ha sido evaluada en base a aproximaciones sistemáticas filogenéticas que permitan considerar la validez evolutiva de esta propuesta. A la fecha el único análisis comparativo realizado con otras especies de la familia utilizó caracteres morfológicos y sugiere que Helcogrammoides pertenecería a la tribu Karalepini junto al género monotípico Karalepis, tribu considerada como monofilética en base a las sinapomorfías morfológicas. En este trabajo se evalúa la hipótesis taxonómica de Rosenblatt y la monofilia de la tribu Karalepini mediante aproximaciones filogenéticas basadas en datos moleculares y morfológicos. Los resultados sugieren que el género Helcogrammoides es un género monofilético que difiere de Tripterygion tanto morfológica como molecularmente, respaldando la hipótesis de Rosenblatt. A su vez el análisis filogenético molecular, y de datos moleculares y morfológicos concatenados, agrupan el género Karalepis junto al género Tripterygion en un clado separado del género Helcogrammoides, refutando la monofilia de la tribu Karalepini y sugiriendo que los caracteres morfológicos que sustentaban la tribu podrían corresponder a homoplasias que oscurecen los resultados del análisis morfológico basado en el criterio de parsimonia y que explican la baja probabilidad a posteriori de este clado en el análisis Bayesiano

Nuevos registros de crinoideos (Echinodermata: Crinoidea) en el talud continental de Chile

The presence of Solanometra antarctica has been reported in the continental slope of central Chile, however, some studies suggest that this species could have been confused with Florometra magellanica. In this study, 11 crinoid specimens obtained in the continental slope of Central Chile were analyzed and compared with other specimens previously collected in that same region and catalogued as Florometra magellanica. The morphological and meristic characteristics confirm that the crinoids collected in Central Chile, off Concepción and Los Vilos, correspond to Florometra magellanica

Environmental and ecological factors mediate taxonomic composition and body size of polyplacophoran assemblages along the Peruvian Province

Indexación: ScopuIntertidal communities’ composition and diversity usually exhibit strong changes in relation to environmental gradients at different biogeographical scales. This study represents the first comprehensive diversity and composition description of polyplacophoran assemblages along the Peruvian Province (SE Pacific, 12°S–39°S), as a model system for ecological latitudinal gradients. A total of 4,775 chitons from 21 species were collected on twelve localities along the Peruvian Province. This sampling allowed us to quantitatively estimate the relative abundance of the species in this assemblage, and to test whether chitons conform to elementary predictions of major biogeographic patterns such as a latitudinal diversity gradient. We found that the species composition supported the division of the province into three ecoregional faunal groups (i.e. Humboldtian, Central Chile, and Araucanian). Though chiton diversity did not follow a clear latitudinal gradient, changes in species composition were dominated by smaller scale variability in salinity and temperature. Body size significantly differed by ecoregions and species, indicating latitudinal size-structure assamblages. In some localities body size ratios differed from a random assemblage, evidencing competition at local scale. Changes in composition between ecoregions influence body size structure, and their overlapping produce vertical size segregation, suggesting that competition coupled with environmental conditions structure these assemblages. © 2019, The Author(s).https://www-nature-com.recursosbiblioteca.unab.cl/articles/s41598-019-52395-

World squid fisheries

Peer reviewedPublisher PD

Non-target screening with high-resolution mass spectrometry: critical review using a collaborative trial on water analysis

In this article, a dataset from a collaborative nontarget screening trial organised by the NORMAN Association is used to review the state-of-the-art and discuss future perspectives of non-target screening using high-resolution mass spectrometry in water analysis. A total of 18 institutes from 12 European countries analysed an extract of the same water sample collected from the River Danube with either one or both of liquid and gas chromatography coupled with mass spectrometry detection. This article focuses mainly on the use of high resolution screening techniques with target, suspect, and non-target workflows to identify substances in environmental samples. Specific examples are given to emphasise major challenges including isobaric and co-eluting substances, dependence on target and suspect lists, formula assignment, the use of retention information, and the confidence of identification. Approaches and methods applicable to unit resolution data are also discussed. Although most substances were identified using high resolution data with target and suspect-screening approaches, some participants proposed tentative non-target identifications. This comprehensive dataset revealed that nontarget analytical techniques are already substantially harmonised between the participants, but the data processing remains time-consuming. Although the objective of a Bfullyautomated identification workflow^ remains elusive in the short term, important steps in this direction have been taken, exemplified by the growing popularity of suspect screening approaches. Major recommendations to improve non-target screening include better integration and connection of desired features into software packages, the exchange of target and suspect lists, and the contribution of more spectra from standard substances into (openly accessible) databases.This work was supported in part by the SOLUTIONS project, which received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under Grant Agreement No. 603437