Primeras evidencias de huevos de resistencia de Acartia bifilosa en sedimentos de estuarios de Urdaibai (Golfo de Bizkaia): abundancia y éxito de eclosión

The abundance and hatching success of Acartia bifilosa resting eggs in subtidal sediments of the Urdaibai estuary was analysed in the context of a study on the spatial and temporal dynamics of this species. Two sediment cores of 20 to 30 cm depth were obtained at two sites of the middle zone, where the accumulation of mud and organic particles is favoured. Laboratory incubations were performed to determine the hatching success of eggs and identify newborns. Resting egg abundance was around 107 eggs m-2, and was higher at the site where the A. bifilosa population maintains an optimal position in the water column. The lower egg abundance in upper layers, as corresponds to winter, was associated with the seasonal dynamics of planktonic populations. On average, the hatching success was >50% at both sites. The lack of significant differences in the hatching success according to sediment depth suggests that eggs remain viable after being buried for a long-time in anoxic conditions. This enables us to infer that the benthic egg bank of A. bifilosa in this estuary is a safe source of recruits into the planktonic population, and plays a crucial role in recuperationand maintenance of the population.Se analizó la abundancia y éxito de eclosión de los huevos de resistencia de Acartia bifilosa en sedimentos submareales del estuario de Urdaibai, en un contexto sobre el estudio de la dinámica espacio-temporal de esta especie. Se obtuvieron dos cores de 20-30 cm de profundidad en dos puntos de la zona media del estuario, donde la acumulación de partículas se ve favorecida. Se realizaron incubaciones en laboratorio para determinar el éxito de eclosión de los huevos y la identificación de los recién nacidos. La abundancia de los huevos de resistencia fue alrededor de 107 huevos m-2, siendo mayor en el punto donde la población de A. bifilosa mantiene su posición óptima en la columna de agua. La menor abundanciade huevos de las capas superiores se asoció a la dinámica estacional de la población planctónica. De media, el éxito de eclosión fue >50% en ambos puntos. La ausencia de diferencias significativas en el éxito de eclosión respecto a la profundidad del sedimento sugiere que los huevos permanecen viables incluso tras una larga acumulación en condiciones anóxicas. Esto nos permite inferir que el banco de huevos bentónicos de A. bifilosa en este estuario es una fuente segura de reclutas a la población planctónica y que juega un papel crucial en la recuperación y mantenimiento de la población

On Small Satellites for Oceanography: A Survey

The recent explosive growth of small satellite operations driven primarily from an academic or pedagogical need, has demonstrated the viability of commercial-off-the-shelf technologies in space. They have also leveraged and shown the need for development of compatible sensors primarily aimed for Earth observation tasks including monitoring terrestrial domains, communications and engineering tests. However, one domain that these platforms have not yet made substantial inroads into, is in the ocean sciences. Remote sensing has long been within the repertoire of tools for oceanographers to study dynamic large scale physical phenomena, such as gyres and fronts, bio-geochemical process transport, primary productivity and process studies in the coastal ocean. We argue that the time has come for micro and nano satellites (with mass smaller than 100 kg and 2 to 3 year development times) designed, built, tested and flown by academic departments, for coordinated observations with robotic assets in situ. We do so primarily by surveying SmallSat missions oriented towards ocean observations in the recent past, and in doing so, we update the current knowledge about what is feasible in the rapidly evolving field of platforms and sensors for this domain. We conclude by proposing a set of candidate ocean observing missions with an emphasis on radar-based observations, with a focus on Synthetic Aperture Radar.Comment: 63 pages, 4 figures, 8 table

Reduced Survival and Disruption of Female Reproductive Output in Two Copepod Species (Acartia clausi and A. tonsa) Exposed to the Model Endocrine Disruptor 17α-Ethinylestradiol

Estuaries are heavily impacted by pollutants from different sources such as urban sewage, industrial waste and agricultural runoff. Endocrine-disrupting chemicals (EDCs) are very concerning pollutants to estuarine wildlife, but little is known about their impact on microscopic biota such as zooplankton. The aim of this work was to investigate the effects of a model EDC, the 17α-ethinylestradiol (EE2), on two copepod species inhabiting the Basque coast (Southeastern Bay of Biscay) estuaries: Acartia clausi (autochthonous neritic species) and Acartia tonsa (non-indigenous brackish species). Female copepods were collected at population maximum time (spring for A. clausi and summer for A. tonsa) and exposed individually to 5 ng/L (low), 5 µg/L (medium) and 500 µg/L EE2 (high) doses, from environmental concentrations found in sewage effluents to toxicological concentrations. After 24 h exposure, the survival rate of experimental individuals was checked and the lethal concentration LC50 was calculated. The number of egg-producing females and the amount of egg laying and egg hatching were recorded. The integrated biomarker index (IBR) was calculated to integrate the overall effects of EE2 exposure. Both species had reduced survival rates at 500 µg/L, and the LC50 was lower in A. tonsa (158 µg/L) compared to A. clausi (398 µg/L). The number of eggs laid was significantly reduced in A. clausi at EE2 medium and high doses, while a reduction in the number of eggs in A. tonsa was observed only at the high dose. However, no significant differences were detected in the egg hatching success of exposed A. clausi and A. tonsa. IBR index showed that EE2 had the most detrimental effects on A. tonsa and A. clausi females at the 500 µg/L dose. In conclusion, after 24 h of exposure, EE2 reduced female copepod survival and disrupted reproductive output, but only at high non-environmentally relevant concentrations.Funded by the Basque Government (IT1743-22) and UPV/EHU (UFI 11/37). T.H. was a holder of an Erasmus Mundus master grant

Impact of Colonizer Copepods on Zooplankton Structure and Diversity in Contrasting Estuaries

The impact of the occurrence of the non-indigenous species (NIS) Acartia tonsa, Oithona davisae, and Pseudodiaptomus marinus and of the range-expanding copepods Acartia bifilosa and Calanipeda aquaedulcis on the structure and diversity of zooplankton communities was analyzed using 18 years (1998-2015) time series from the contrasting estuaries of Bilbao and Urdaibai (Basque coast, Bay of Biscay). Changes in the structure of communities were assessed by using multivariate analyses of taxa abundances and changes in diversity by using descriptors of alpha, beta, and gamma diversity. The most evident changes occurred at the upper reaches of the estuary of Bilbao, where an abundant and less diverse brackish community, dominated by the NIS, A. tonsa and O. davisae, succeeded a low abundance and more diverse community of neritic origin. The later establishment of C. aquaedulcis was linked to further changes in the structure of the community and a progressive increase in diversity. The seasonal pattern of diversity at the inner estuary and the beta diversity in the estuary were also significantly affected by the arrival of the NIS and C. aquaedulcis. In contrast, the original low diversity brackish community of the estuary of Urdaibai, clearly dominated by A. bifilosa, was far less affected by the arrival of the same copepod NIS, and A. bifilosa remained as the species best related to the changes in zooplankton structure and diversity in the brackish habitats of the estuary.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was supported by the University of the Basque Country (UPV/EHU) (UPV/EHU, GIU19/059) and the Basque Government (PIBA2020-1-0028 & IT1723-22) and through a grant to Z. Barroeta to carry out her PhD (UPV/EHUn Ikertzaileak Prestatzeko Kontratazio Deialdia 2016)

Activation of the DnaK-ClpB Complex is Regulated by the Properties of the Bound Substrate

The chaperone ClpB in bacteria is responsible for the reactivation of aggregated proteins in collaboration with the DnaK system. Association of these chaperones at the aggregate surface stimulates ATP hydrolysis, which mediates substrate remodeling. However, a question that remains unanswered is whether the bichaperone complex can be selectively activated by substrates that require remodeling. We find that large aggregates or bulky, native-like substrates activates the complex, whereas a smaller, permanently unfolded protein or extended, short peptides fail to stimulate it. Our data also indicate that ClpB interacts differently with DnaK in the presence of aggregates or small peptides, displaying a higher affinity for aggregate-bound DnaK, and that DnaK-ClpB collaboration requires the coupled ATPase-dependent remodeling activities of both chaperones. Complex stimulation is mediated by residues at the beta subdomain of DnaK substrate binding domain, which become accessible to the disaggregase when the lid is allosterically detached from the beta subdomain. Complex activation also requires an active NBD2 and the integrity of the M domain-ring of ClpB. Disruption of the M-domain ring allows the unproductive stimulation of the DnaK-ClpB complex in solution. The ability of the DnaK-ClpB complex to discriminate different substrate proteins might allow its activation when client proteins require remodeling.A.A. thanks the Basque Government for a Predoctoral Fellowship. The excellent technical assistance of N. Orozco is gratefully acknowledged. We also thank Mathias P. Mayer for the plasmid encoding the DnaK SBD. This work was supported by grants BFU2016-75983 (AEI/FEDER, UE) and IT709-13 (Basque Government)

Capacitación a los propietarios de establecimientos comerciales informales del sector del Quiroga de la ciudad de Bogotá D.C., en temas contables que les faciliten la organización, preparación y presentación de información financiera básica.

En este trabajo encontramos la problematización, la cual parte de los antecedentes situacionales que se establecieron desde la contexto contable de los establecimientos comerciales del barrio Quiroga de la ciudad de Bogotá D.C., los cuales en un número significativo no hacen una presentación adecuada de la situación financiera de su actividad económica que en su gran parte se establece por la falta de conocimiento en los conceptos básicos de contabilidad o en el creer que no son necesarios en el momento de la toma de decisiones para el crecimiento y fortalecimiento de su entidad

Response of native and non-indigenous zooplankton to inherent system features and management in two Basque estuaries: A niche decomposition approach

The realized ecological niches of native zooplankton and non-indigenous species (NIS) were analysed in the contrasting estuaries of Bilbao and Urdaibai from 1998 to 2015 in order to study their responses to the particular features of each estuary and the biotic and abiotic changes along the study period. The marginality and tolerance of zooplankton taxa was estimated for the two estuaries together using the OMI analysis, whilst, by means of the WitOMI analysis, niches were differentiated into spatial subniches to assess the differences between estuaries and into temporal subniches to determine the variations in time within each estuary. The changes in the niche overlap of the main native and NIS species were calculated with the D-metric. Results showed that the combined effect of salinity gradients and seasonal variations, linked to temperature, defined the main spatio-temporal niches of zooplankton taxa in the overall environmental scenario of both estuaries. Thus, those factors separated winter-spring neritic, summer-autumn neritic, warm water affinity brackish and limnetic species. Secondarily, river discharge and hydrological stability accounted for the higher presence of freshwater and some brackish species in the estuary of Bilbao and tychoplanktonic organisms in the estuary of Urdaibai. At the regional scale the marginality and tolerance of zooplankton taxa reflected a combination of spatial and seasonal niche breadth and difference of abundance between estuaries. The number of taxa with niches not clearly explained by the environmental variables studied was higher in the estuary of Urdaibai, whilst the new arriving species occupied realized niches well defined by the environmental variables and overall zooplankton taxa showed a better discrimination from generalist to specialist behaviours in the estuary of Bilbao. This was related to inherent abiotic and biotic features of each estuary, which make the estuary of Urdaibai more refractory to the settlement of NIS species. Moreover, in the estuary of Bilbao, several neritic and brackish species experienced temporal changes in niche breadth and overlap that was attributed both to the environmental improvement related to rehabilitation plans in the system and the impact of the species that arrived during the study period. In the estuary of Urdaibai only small changes attributable to the limited impact of NIS were inferred, since no meaningful changes in environmental conditions were perceived.This work was supported by the University of the Basque Country through research funds to Consolidated Research Groups (GIU16/69) and through a grant to Z. Barroeta. The authors thank the WGEUROBUS of the International Council for the Exploration of the Sea (ICES) for facilitating research on P. marinus

The Role of Microplastics in Marine Pathogen Transmission: Retrospective Regression Analysis, Experimental Design, and Disease Modelling

Marine wildlife and aquaculture species can accumulate large amounts of marine microplastic debris (MMD) (<1 mm) carrying pathogens, thus threatening the health of marine ecosystems and posing a risk to food safety and human health. Here, we outline a theoretical three-perspective approach for studying the relationship between MMD and disease. First, we provide a framework for retrospective analysis of MMD and pathogen loads in marine animal tissues to assess the relationship between these and other environmental variables in order to decide whether a compound or pathogen should be considered an emerging substance or organism. Second, we describe an experimental design for testing the effects of a variety of microplastics on infection intensity in two model species (oysters and zebrafish). Finally, we create a theoretical susceptible–infected microplastic particle and pathogen transmission model for bivalves and fish. Overall, the experiments and models we propose will pave the way for future research designed to assess the role of MMD as a vector for marine and human pathogens. This multi-faceted approach needs to be an urgent priority of the EU Strategic Research Innovation Agenda for addressing marine disease challenges related to MMD.This work was conceived under the research framework outlined by the National Science Foundation Evolution and Ecology of Infectious Diseases (EEID) Program, grant OCE-1216220. Funding was provided by the University of the Basque Country (UPV/EHU, GIU19/059) and the Basque Government (PIBA2020-1-0028). We appreciate this support