Contribution of marine zooplankton time series to the United Nations Decade of Ocean Science for Sustainable Development

Zooplankton play a central role in marine trophic webs, influencing both biogeochemistry and productivity of the oceans. Changes in their communities are important indicators of overall ecosystem health and global change impacts. With increasing exploitation and pressures on the marine environment, there is a growing need for high-resolution monitoring of marine zooplankton to provide detailed information about seasonal to decadal changes at local, regional, and global scales. This crucial knowledge is gathered mainly through long-term time series, which are key to characterizing and forecasting changes in marine zooplankton assemblages. In this Introduction, and through the articles included in this Themed Article Set, we bring together new insights, issuing from data time series, into zooplankton population dynamics.We also take up the application of such time series to the understanding of global change impacts on marine ecosystems and in providing advice on sustainable management of marine ecosystem resources and services. We highlight the importance of maintaining and supporting long-term marine zooplankton time series as key contributors to the development and advancement of the United Nations’ Decade of Ocean Science for Sustainable Development Goal 13-Climate action and Goal 14-Life below water.Versión del editor2,27

Individual growth rate (IGR) and aminoacyl-tRNA synthetases (AARS) activity as individual-based indicators of growth rate of North Pacific krill, Euphausia pacifica

We investigated aminoacyl-tRNA synthetases (AARS) activity and individual growth rate (IGR) as individual-based in situ indicators of growth in adult krill, Euphausia pacifica. AARS enzymes catalyze the first step in protein synthesis while the IGR method is based on changes in body length during molting. Growth rates of field-collected krill were measured via the IGR method and individuals were subsequently preserved for AARS analysis to yield paired measurements. Our results show that conditions during the IGR incubation period influenced AARS activity in these individuals precluding a direct comparison but revealing the different timescales across which these two measures integrate. Importantly, they show that AARS activity provides a snap-shot image of an organism's metabolism, while IGR of krill is thought to integrate their environmental experience over several days. Each method would require repeated measurements to estimate population growth rates integrated over seasonal or generational time scales. As part of this project, we investigated how specific the AARS assay is to protein synthesis by testing a modified protocol that includes an additional blank and found evidence that the current assay may be measuring other cellular processes in addition to its intended signal. Our results suggest that a new NADH Blank might be optimized to improve the specificity of the assay.Postprint2,26

The effect of a strong warm winter on subtropical zooplankton biomass and metabolism

Winter 2010 was the warmest of the last 30 years in the subtropical oceanic waters north of the Canary Islands. Sea surface temperature was always above 19°C, promoting a strong stratification and preventing the expected late winter bloom. The knowledge of how planktonic organisms respond to such a warm scenario is of paramount importance to predict the effect of future ocean changes. In this study, zooplankton biomass and gut fluorescence (GF), electron transport system (ETS) activity, and aminoacyl-tRNA synthetases (AARS) activity were measured as proxies of metabolism in the oceanic waters north of the Canary Islands during the winter–spring period of 2010. Mesozooplankton biomass, GF, and ETS activity showed lower values compared with previous studies in the area under normal winter conditions. However, relatively higher than expected mesozooplankton biomass was observed during the normal postbloom period in these waters, and AARS activities were relatively high throughout the period studied. This apparent paradox could be tentatively explained by the observed inputs of dust deposition from the Sahara desert. Our findings show how warming and dust events may interact, affecting the zooplankton biomass and metabolism in these subtropical waters

Are we missing a mesopelagic-demersal coupling?

Despite demersal trawling monitoring programs are not aimed at quantifying mesopelagic organisms, they are recurrently captured as by catch between 30 and 800 m depth. These species are mostly diel vertical migrants, with differentiated behavior from benthic and demersal ones. Nevertheless, they are sometimes captured in large quantities (both abundance and biomass) although absent on other occasions. The co-occurrence observed with demersal populations may probably be due to the daytime and location of samplings, i.e. depth and type of bottom (habitat). In order to understand the mesopelagic-demersal coupling, we discuss spatio-temporal patterns observed along the Spanish Mediterranean coast during the 1994-2012 MEDITS survey.FEM

Horizontal distribution of deep sea microplankton: A new point of view for marine biogeography.

An investigation on microplankton composition and spatial distribution has been carried out around Italian seas. The analysis of 53 samples, collected in 2017 at two depths in 27 different stations, has led to a scenario of horizontal distribution of microplankton. Dinophyta and Ciliophora were chosen as representatives of the whole microplankton community. A total of 60 genera were identified. Cluster analysis of data regarding taxa presence and abundance led us to recognize that similarities between surface stations were more evident than those between deep ones. Furthermore, we conducted an inter-annual comparison with available data from the South Adriatic Sea (2013, 2015). The higher dissimilarity between deep sea samples was also confirmed in a relatively smaller geographic area. The dissimilarity of deep-sea samples does not correspond to a higher habitat diversification, in terms of abiotic parameters. It has been suggested that the negligible biological connectivity in the deep, for those micro-organisms not able to perform wide spatial migrations, could produce such a biological diversificatio

Ontogenetic Responses of Calanus chilensis to Hypoxia from Northern Chile (23ºS), Humboldt Current Ecosystem

Eastern Boundary Upwelling Systems are being subjected to expansion, intensification and shoaling of Oxygen Minimum Zones (OMZ's), as a result of ongoing climate change. To understand how dominant epipelagic copepods may respond to stressful conditions induced by low oxygen, we experimentally studied the effect of hypoxia over the stage-specific physiology of Calanus chilensis from the Mejillones Bay (23°S — 70°W), northern Chile, during the winters of 2013 and 2014. Females, eggs and nauplii (NI to NIV) of C. chilensis were incubated under hypoxia (~0.7 mg O2 L-1) and normoxia (~8.3 mg O2 L-1) conditions at a constant temperature of 14ºC as to estimate egg production rate (EPR), hatching success (HS) and naupliar growth and development time. Additionally, we estimated survivorship by using Neutral Red technique, and also examined female metabolism by measuring specific activity of the enzymes Aminoacyl-tRNA synthetases (spAARS) (growth index) and the electron transport system (spETS) (potential respiration). Survival of females and EPR were not significantly affected by dissolved oxygen (DO) conditions, coinciding with no significant changes in their metabolism. By contrast, HS was reduced from normoxia (70%) to hypoxia (30%), whereas naupliar growth (NI to NIII) was lower under hypoxia (0.155 ± 0.007 d-1) than normoxia (0.237 ± 0.006 d-1), resulting also in a longer development time, 6.490 ± 0.353 d and 4.238 ± 0.149 d, respectively. Most eggs and nauplii collected at the end of the experiments were alive, although a higher proportion of organisms were recovered in normoxia than hypoxia. Our results revealed stage-specific responses to hypoxia in C. chilensis and the importance of ontogenetic responses to variable levels of oxygenation in the upwelling zone

Criminalización y estigmatización de la protesta feminista en México desde la perspectiva de las colectivas activistas

In recent years, the feminist movement in Mexico has had a greater presence in the public space in various cities of the country. Parallel to this phenomenon, there has been a criminalization and stigmatization of feminist protest in which the State plays an important role, while society and the media play a secondary role. This study includes an analysis of the dynamics in which the collective action of women against the eradication of violence in Mexico has been criminalized and stigmatized by various actors through 11 interviews with Mexican feminist collectives and a Twitter Space on criminalization of protest conducted by "Somos el medio", which is a critical and independent news media on the Internet, produced in March 2022. The main findings point to the diversification of types of criminalization by the State, and of stigmatization by the media and users of socio-digital network sites.En los últimos años, el movimiento feminista en Méjico ha tenido una mayor presencia en el espacio público en diversas ciudades del país. En paralelo a este fenómeno se ha presentado una criminalización y estigmatización de la protesta feminista donde el Estado juega un rol importante, mientras que la sociedad y los medios lo hacen en un segundo momento. El presente estudio comprende un análisis de las dinámicas en las que la acción colectiva de las mujeres contra la erradicación de la violencia en Méjico, ha sido criminalizada y estigmatizada, por diversos actores mediante 11 entrevistas efectuadas a colectivas feministas mexicanas y un Twitter Space sobre criminalización de la protesta realizado por “Somos el medio”, un medio informativo crítico e independiente en Internet, realizado en marzo de 2022. Los principales hallazgos apuntan a la diversificación de los modos de criminalización por parte del Estado, y de la estigmatización por parte de los medios y los usuarios de redes sociodigitales

Spatio-temporal variability of the zooplankton community in the SW Mediterranean 1992–2020: Linkages with environmental drivers

Variability in the spatial and temporal distribution of the mesozooplankton abundance in the N Alboran Sea (SW Mediterranean) was assessed intermittently from 2010 to 2020, and compared with 1992–2000 historical time series data. Total abundance of mesozooplankton was significantly higher in the coast than in the shelf and slope waters. There were significant differences in mesozooplankton abundance between 1992–2000 and 2010–2020 at the three zones. Copepods dominated the mesozooplankton during winter and spring, but cladocerans and doliolids also became important components of the community in summer and autumn. We found significant increases between the first and the second decadal periods in the abundance of copepods, appendicularians, holoplanktonic gastropods and siphonophores in the shelf. However, in the coast, copepod nauplii, doliolids, gastropods and siphonophores increased, while euphausiids abundance decreased significantly. These trends contrast with the ongoing decline of the sardine stocks in European waters. Increasing temperature and decreasing predation pressure are suggested to be the main drivers of mesozooplankton variability.Versión del editor3,26