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

Subtidal macrozoobenthos communities from northern Chile during and post El Niño 1997–1998

Despite a large amount of climatic and oceanographic information dealing with the recurring climate phenomenon El Niño (EN) and its well known impact on diversity of marine benthic communities, most published data are rather descriptive and consequently our understanding of the underlying mechanisms and processes that drive community structure during EN are still very scarce. In this study, we address two questions on the effects of EN on macrozoobenthic communities: (1) how does EN affect species diversity of the communities in northern Chile? and (2) is EN a phenomenon that restarts community assembling processes by affecting species interactions in northern Chile? To answer these questions, we compared species diversity and co-occurrence patterns of soft-bottoms macrozoobenthos communities from the continental shelf off northern Chile during (March 1998) and after (September 1998) the strong EN event 1997–1998. The methods used varied from species diversity and species co-occurrence analyses to multivariate ordination methods. Our results indicate that EN positively affects diversity of macrozoobenthos communities in the study area, increasing the species richness and diversity and decreasing the species dominance. EN represents a strong disturbance that affects species interactions that rule the species assembling processes in shallow-water, sea-bottom environments

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio

Localised Effects of a Mega-Disturbance: Spatiotemporal Responses of Intertidal Sandy Shore Communities to the 2010 Chilean Earthquake.

Determining the effects of unpredictable disturbances on dynamic ecological systems is challenged by the paucity of appropriate temporal and spatial coverage of data. On 27 February 2010, an 8.8 Mw mega-earthquake and tsunami struck central Chile and caused coastal land-level changes, massive damage to coastal infrastructure, and widespread mortality of coastal organisms. Wave-exposed sandy beaches showed significant changes of species abundances from before to after the earthquake, but the highly dynamic biotic and abiotic conditions of these habitats make difficult to draw clear-cut conclusions from these patterns. Here, we analysed a beyond-BACI (Before-After Control-Impact) sampling design to test whether the effects of the Maule earthquake on sandy-shore species diversity, abundance, and structure were heterogeneous along the shore. Invertebrate species abundances were quantified before (i.e. February 2010) and after (i.e. March 2010, September 2010, and March 2011) the earthquake at three sandy shores randomly located within the earthquake rupture area and three sites within a "control" area located >400 km southward from epicentre. Immediately after the earthquake took place, the three sites located in the rupture area showed anomalous beach-profile uplifts that did not comply with the erosion (i.e. "negative" uplifts) that regularly occurs during late summer in the region. Species richness, abundance, and community structure significantly varied from before to after the strike, but these patterns of change varied among sites within both areas. Only the site with the strongest and persistent beach-profile uplift within the rupture area showed significant concomitant changes in species richness and community structure; after 13 months, this community showed a similar multivariate structure to the before-disturbance state. This site, in particular, was located in the section of the rupture area that received most of the impact of the after-earthquake tsunami. Therefore, our results suggest that the effects of the Maule mega-earthquake on the ecological communities were spatially heterogeneous and highly localised. We suggest that high mobility and other species' adaptations to the dynamic environmental conditions of sandy beaches might explain the comparatively high resilience of these assemblages. With this work we hope to motivate further experimental research on the role of individual- and population-level properties in the response of sandy-beach communities to interacting sources of disturbances

DIVERSIDAD DE MACROINVERTEBRADOS ASOCIADOS A ARRECIFES DE PHRAGMATOPOMA MOERCHI KINBERG, 1867 (POLYCHAETA: SABELLARIIDAE) EN EL INTERMAREAL ROCOSO DE COCHOLGÜE, CHILE MACROINVERTEBRATE DIVERSITY ASSOCIATED TO REEFS OF PHRAGMATOPOMA MOERCHI KINBERG, 1867 (POLYCHAETA: SABELLARIIDAE) IN THE INTERTIDAL ROCKY SHORE AT COCHOLGÜE, CHILE

Las agregaciones monoespecíficas son comunes en el intermareal rocoso. Una de estas especies gregarias es el poliqueto tubícola Phragmatopoma moerchi, el cual construye arrecifes de tamaño variable en el intermareal rocoso. Estos arrecifes proveen de refugio y alimento a muchas especies de invertebrados. El objetivo de este trabajo es caracterizar la macrofauna asociada a estos arrecifes y determinar cómo afecta el tamaño de éstos a algunos parámetros comunitarios. Nueve muestras fueron extraídas del intermareal de Cocholgüe (36° 35'S), entre octubre y diciembre de 2001. En laboratorio, las muestras fueron pesadas y la fauna asociada fue agrupada por taxa y determinada, cuando fue posible, al nivel taxonómico más bajo posible. Luego se obtuvieron los descriptores comunitarios (número de individuos, diversidad, riqueza, dominancia y uniformidad) para relacionarlos con el tamaño de los arrecifes (TA). Fueron encontrados un total de 487 especímenes de 43 taxa pertenecientes a nueve grupos mayores. Los taxa con más especies presentes fueron Mollusca y Polychaeta (17 y 10, respectivamente). Relaciones directas y significativas fueron encontradas entre el TA y algunos descriptores comunitarios; los valores de diversidad fueron altos, pero no significativamente correlacionados con el TA. Los resultados del presente estudio demuestran que estos arrecifes constituyen un microhábitat que alberga una gran cantidad y diversidad de invertebrados, y por lo tanto, podrían ser importantes para mantener la biodiversidad local<br>Single species aggregations are common in the rocky intertidal shore. One of such gregarious species is the tubicolous polychaete Phragmatopoma moerchi, which builds reefs of variable size on the rocky intertidal. These reefs provide refuge and food to many invertebrate species. The aim of this work is to characterize the macrofauna associated to these reefs and to determine the possible relationship between reef size (RS) and parameters of the associated community. Nine samples were taken from the intertidal at Cocholgüe (36° 35'S), between October and December, 2001. In the laboratory the samples were weighted, and the associated fauna was classified by taxa, and when possible, identified to species level. RS was then related with the following community descriptors: total number of individuals, species richness, diversity, dominance and evenness. Were found a total of 487 specimens of 43 taxa belonging to nine major groups. The taxa with more species present were Mollusca and Polychaeta (17 and 10, respectively). Direct and significant relationships were found between RS and some the community descriptors; diversity values were high but not significantly correlated with RS. The results of the present study demonstrate that these reefs shelter a dense and diverse invertebrate fauna, and therefore they are likely important for maintaining local biodiversit

Mean abundances (± 1 SD) for the four most abundant species in the intertidal sandy shores.

<p>Abundances values are given for the rupture and control areas registered before (February 2010) and after (March 2010, September 2010 and March 2011) the Maule earthquake (27 February 2010). The listed species are the anomuran crab <i>Emerita analoga</i> (<i>Ea</i>, low intertidal), the cirolanid isopod <i>Excirolana hirsuticauda</i> (<i>Eh</i>, mid-intertidal), the talitrid amphipod <i>Orchestoidea tuberculata</i> (<i>Ot</i>, high intertidal), and the ophelid polychaete <i>Euzonus heterocirrus</i> (<i>Eu</i>, low/mid-intertidal).</p

Number of invertebrate species in the intertidal sandy shores.

<p>Values are given for before (February 2010) and after (March 2010, September 2010, and March 2011) the earthquake and tsunami of February 27, 2010. Error bars denote ± 1 S.E.</p

Principal Coordinates Analysis (PCoA) of the spatiotemporal patterns of community structure of six intertidal sandy shores.

<p>Ordination plot includes the rupture and control areas (empty and filled symbols, respectively) before (February 2010) and after (March 2010, September 2010, and March 2011) the earthquake and tsunami of February 27, 2010. Each symbol represent the centroid of five replicate transects deployed in each site and time.</p

PERMANOVA for the spatiotemporal effects of the Maule earthquake on intertidal sandy-shore assemblages.

<p>The analyses were conducted on a Euclidean distance matrix for species richness and total abundance, and on a Bray-Curtis resemblance matrix of species abundances for community structure. The analysis was performed using Time (four sampling times: February 2010, March 2010, September 2010, and March 2011) and Area (two areas: Rupture and Control) as fixed factors, and Site (three sites located within each area) as random factor nested in Area. CV% = Components of variation.</p