Uncoupled seasonal variability of transparent exopolymer and Coomassie stainable particles in coastal Mediterranean waters: Insights into sources and driving mechanisms

Transparent exopolymer particles (TEP) and Coomassie stainable particles (CSP) are gel-like particles, ubiquitous in the ocean, that affect important biogeochemical processes including organic carbon cycling by planktonic food webs. Despite much research on both groups of particles (especially TEP) over many years, whether they exist as distinctly stainable fractions of the same particles or as independent particles, each with different driving factors, remains unclear. To address this question, we examined the temporal dynamics of TEP and CSP over 2 complete seasonal cycles at 2 coastal sites in the Northwestern Mediterranean Sea, the Blanes Bay Microbial Observatory (BBMO) and the L’Estartit Oceanographic Station (EOS), as well as their spatial distribution along a coast-to-offshore transect. Biological, chemical, and physical variables were measured in parallel. Surface concentrations (mean + standard deviation [SD]) of TEP were 36.7 + 21.5 µg Xanthan Gum (XG) eq L–1 at BBMO and 36.6 + 28.3 µg XG eq L–1 at EOS; for CSP, they were 11.9 + 6.1 µg BSA eq L–1 at BBMO and 13.0 + 5.9 µg BSA eq L–1 at EOS. Seasonal variability was more evident at EOS, where surface TEP and CSP concentrations peaked in summer and spring, respectively, and less predictable at the shore-most station, BBMO. Vertical distributions between surface and 80 m, monitored at EOS, showed highest TEP concentrations within the surface mixed layer during the stratification period, whereas CSP concentrations were highest before the onset of summer stratification. Phytoplankton were the main drivers of TEP and CSP distributions, although nutrient limitation and saturating irradiance also appeared to play important roles. The dynamics and distribution of TEP and CSP were uncoupled both in the coastal sites and along the transect, suggesting that they are different types of particles produced and consumed differently in response to environmental variability

Viral-mediated microbe mortality modulated by ocean acidification and eutrophication: Consequences for the carbon fluxes through the microbial food web

Anthropogenic carbon emissions are causing changes in seawater carbonate chemistry including a decline in the pH of the oceans. While its aftermath for calcifying microbes has been widely studied, the effect of ocean acidification (OA) on marine viruses and their microbial hosts is controversial, and even more in combination with another anthropogenic stressor, i.e., human-induced nutrient loads. In this study, two mesocosm acidification experiments with Mediterranean waters from different seasons revealed distinct effects of OA on viruses and viral-mediated prokaryotic mortality depending on the trophic state and the successional stage of the plankton community. In the winter bloom situation, low fluorescence viruses, the most abundant virus-like particle (VLP) subpopulation comprising mostly bacteriophages, were negatively affected by lowered pH with nutrient addition, while the bacterial host abundance was stimulated. High fluorescence viruses, containing cyanophages, were stimulated by OA regardless of the nutrient conditions, while cyanobacteria of the genus Synechococcus were negatively affected by OA. Moreover, the abundance of very high fluorescence viruses infecting small haptophytes tended to be lower under acidification while their putative hosts\u27 abundance was enhanced, suggesting a direct and negative effect of OA on viral–host interactions. In the oligotrophic summer situation, we found a stimulating effect of OA on total viral abundance and the viral populations, suggesting a cascading effect of the elevated pCO2 stimulating autotrophic and heterotrophic production. In winter, viral lysis accounted for 30 ± 16% of the loss of bacterial standing stock per day (VMMBSS) under increased pCO2 compared to 53 ± 35% in the control treatments, without effects of nutrient additions while in summer, OA had no significant effects on VMMBSS (35 ± 20% and 38 ± 5% per day in the OA and control treatments, respectively). We found that phage production and resulting organic carbon release rates significantly reduced under OA in the nutrient replete winter situation, but it was also observed that high nutrient loads lowered the negative effect of OA on viral lysis, suggesting an antagonistic interplay between these two major global ocean stressors in the Anthropocene. In summer, however, viral-mediated carbon release rates were lower and not affected by lowered pH. Eutrophication consistently stimulated viral production regardless of the season or initial conditions. Given the relevant role of viruses for marine carbon cycling and the biological carbon pump, these two anthropogenic stressors may modulate carbon fluxes through their effect on viruses at the base of the pelagic food web in a future global change scenario

La recollida d'oli de cuina, analitzada

Què fer amb l'oli de cuina, com recollir-lo després de l'ús a les cuines domèstiques és un problema que encara no té una solució clara. Un estudi realitzat a l'ICTA i a Inèdit, spin off del Parc de Recerca de la UAB, ha utilitzat una metodologia quantitativa de l'Avaluació de la Sostenibilitat del Cicle de Vida (LCSA) per analitzar els diferents mètodes utilitzats fins ara per a la recollida d'oli de cuina usat: les deixalleries urbanes, el porta a porta i la recollida a les escoles. Aquest treball ha arribat a la conclusió que la utilització de les deixalleries urbanes, que recullen altres residus a més de l'oli, és el mètode més sostenible, encara que genera menys benefici social que d'altres sistemes de recollida. Els altres dos sistemes serien menys sostenibles però disposarien de més beneficis socials.Qué hacer con el aceite de cocina, cómo recogerlo después del uso en las cocinas domésticas es un problema que aún no tiene una solución clara. Un estudio realizado en el ICTA y en Inèdit, spin off del Parc de Recerca de la UAB, ha utilizado una metodología cuantitativa de la Evaluación de la Sostenibilidad del Ciclo de Vida (LCSA) para analizar los diferentes métodos utilizados hasta el momento para la recogida de aceite de cocina usado: los centros de recogida urbanos, el puerta a puerta y la recogida en las escuelas. Este trabajo ha llegado a la conclusión de que la utilización de los centros de recogida urbanos, que recogen otros residuos además del aceite, es el método más sostenible, aunque genera menos beneficio social que otros sistemas de recogida. Los otros dos sistemas serían menos sostenibles pero dispondrían de más beneficios sociales

Wind-induced changes in the dynamics of fluorescent organic matter in the coastal NW Mediterranean

Original research paperMarine biogeochemistry dynamics in coastal marine areas is strongly influenced by episodic events such as rain, intense winds, river discharges and anthropogenic activities. We evaluated in this study the importance of these forcing events on modulating seasonal changes in the marine biogeochemistry of the northwestern coast of the Mediterranean Sea, based on data gathered from a fixed coastal sampling station in the area. A 4-year (2011–2014) monthly sampling at four depths (0.5 m, 20 m, 50 m and 80 m) was performed to examine the time variability of several oceanographic variables: seawater temperature, salinity, inorganic nutrient concentrations (NO3−, PO43 − and SiO2), chlorophyll a (Chl a), dissolved organic carbon (DOC) and fluorescent dissolved organic matter (FDOM). FDOM dynamics was predominantly influenced by upwelling events and mixing processes, driven by strong and characteristic wind episodes. SW wind episodes favored the upwelling of deeper and denser waters into the shallower shelf, providing a surplus of autochthonous humic-like material and inorganic nutrients, whereas northerlies favored the homogenization of the whole shelf water column by cooling and evaporation. These different wind-induced processes (deep water intrusion or mixing), reported along the four sampled years, determined a high interannual environmental variability in comparison with other Mediterranean sampling sites. Graphical abstract Image 1 Download : Download high-res image (344KB)Download : Download full-size imageECOSER (CTM2011-15937-E), DOREMI (CTM2012-342949), SUAVE (CTM2014/ 23456/1) and ANIMA (CTM2015-65720) from the Spanish Ministerio de Economía y Competitividad (MINECO) and the Grup de Recerca Consolidat 2014SGR1179 and 2014SGR1029 financed by the Agència de Gestió d'Ajuts Universitaris i de Recerca (AGAUR) from the Generalitat de Catalunya; (JAEPre_2011_00923) from the Agencia Estatal Consejo Su perior de Investigaciones Científicas (CSIC) and the project FERMIO (MINECO, CTM2014-57334-JIN) co-financed with FEDER fundsVersión del editor3,25

COVID-19 lockdown moderately increased oligotrophy at a marine coastal site

8 pages, 4 figures, 2 figures, supplementary figures https://doi.org/10.1016/j.scitotenv.2021.151443.COVID-19 has led to global population lockdowns that have had indirect effects on terrestrial and marine fauna, yet little is known on their effects on marine planktonic communities. We analysed the effect of the spring 2020 lockdown in a marine coastal area in Blanes Bay, NW Mediterranean. We compared a set of 23 oceanographic, microbial and biogeochemical variables sampled right after the strict lockdown in Spain, with data from the previous 15 years after correcting for long-term trends. Our analysis shows a series of changes in the microbial communities which may have been induced by the combination of the decreased nitrogen atmospheric load, the lower wastewater flux and the reduced fishing activity in the area, among other factors. In particular, we detected a slight decrease beyond the long-term trend in chlorophyll a, in the abundance of several microbial groups (phototrophic nanoflagellates and total prokaryotes) and in prokaryotic activity (heterotrophic prokaryotic production and β-glucosidase activity) which, as a whole, resulted in a moderate increase of oligotrophy in Blanes Bay after the lockdown.Data from the specific sampling in 2020 were supported by the MIAU project of the Spanish Ministerio de Ciencia e Innovación, MICINN (RTI2018-101025-B-I00), while previous years were supported by many Spanish and EU projects. Other projects of the MICINN also supported this research: DOGMA (PID2020-112653GB-I00), DIVAS (PID2019-108457RB-I00), and HICCUP (RTI2018-095083-B-I00). We thank Amanda Con and Juan Rodríguez for providing data of the Blanes WWTP. We sincerely thank Irene Forn, Carolina Antequera, Arturo Lucas, Elisabet Laia Sà and Vanessa Balagué for their invaluable laboratory work. The work of the authors was supported by Generalitat de Catalunya Grups de Recerca Consolidats 2017SGR1568 and 2017SGR1011. This study acknowledges institutional support from the “Severo Ochoa Centre of Excellence” accreditation (CEX2019-000928-S).Peer reviewe

Eutrophication and acidification: Do they induce changes in the dissolvedorganic matter dynamics in the coastal Mediterranean Sea?

Original research paperTwo mesocosms experiments were conducted in winter 2010 and summer 2011 to examine how increased pCO2and/or nutrient concentrations potentially perturbate dissolved organic matter dynamics in natural microbialassemblages. Thefluorescence signals of protein- and humic-like compounds were used as a proxy for labileand non-labile material, respectively, while the evolution of bacterial populations, chlorophylla(Chla) anddissolved organic carbon (DOC) concentrations were used as a proxy for biological activity. For both seasons,the presence of elevated pCO2did not cause any significant change in the DOC dynamics (p-valueb0.05). Theconditions that showed the greatest changes in prokaryote abundances and Chlacontent were those amendedwith nutrients, regardless of the change in pH. The temporal evolution offluorophores and optical indices re-vealed that the degree of humification of the organic molecules and their molecular weight changed significantlyin the nutrient-amended treatment. The generation of protein-like compounds was paired to increases in theprokaryote abundance, being higher in the nutrient-amended tanks than in the control. Different patterns inthe magnitude and direction of the generation of humic-like molecules suggested that these changes dependedon initial microbial populations and the availability of extra nutrient inputs. Based on our results, it is expected that in the future projected coastal scenarios the eutrophication processes will favor the transformations of labile and recalcitrant carbon regardless of changes in pCO2.MINECO, European Union, Generalitat de Catalunya, CSICVersión del editor3,25

The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats

The Mediterranean Sea is a marine biodiversity hot spot. Here we combined an extensive literature analysis with expert opinions to update publicly available estimates of major taxa in this marine ecosystem and to revise and update several species lists. We also assessed overall spatial and temporal patterns of species diversity and identified major changes and threats. Our results listed approximately 17,000 marine species occurring in the Mediterranean Sea. However, our estimates of marine diversity are still incomplete as yet—undescribed species will be added in the future. Diversity for microbes is substantially underestimated, and the deep-sea areas and portions of the southern and eastern region are still poorly known. In addition, the invasion of alien species is a crucial factor that will continue to change the biodiversity of the Mediterranean, mainly in its eastern basin that can spread rapidly northwards and westwards due to the warming of the Mediterranean Sea. Spatial patterns showed a general decrease in biodiversity from northwestern to southeastern regions following a gradient of production, with some exceptions and caution due to gaps in our knowledge of the biota along the southern and eastern rims. Biodiversity was also generally higher in coastal areas and continental shelves, and decreases with depth. Temporal trends indicated that overexploitation and habitat loss have been the main human drivers of historical changes in biodiversity. At present, habitat loss and degradation, followed by fishing impacts, pollution, climate change, eutrophication, and the establishment of alien species are the most important threats and affect the greatest number of taxonomic groups. All these impacts are expected to grow in importance in the future, especially climate change and habitat degradation. The spatial identification of hot spots highlighted the ecological importance of most of the western Mediterranean shelves (and in particular, the Strait of Gibraltar and the adjacent Alboran Sea), western African coast, the Adriatic, and the Aegean Sea, which show high concentrations of endangered, threatened, or vulnerable species. The Levantine Basin, severely impacted by the invasion of species, is endangered as well

Seasonal dynamics in abundance and diversity of aerobic anoxygenic phototrophic bacteria in Northwestern Mediterranean waters

SAME13 - 13th Symposium on Aquatic microbial Ecology, 8-13 September 2013, Stresa, ItalyPeer Reviewe

Oceans : the impact of global change on the sea

A phenomenon of exceptional importance such as global change and its multiple effects has been discussed in several Mètode monographs. In recent years, public concern about what we already perceive to be the greatest threat to humanity has not stopped growing; at the same time, the United Nations have proclaimed the period 2021-2030 as the Decade of Ocean Sciences for Sustainable Development, recognising the close relationship between the oceans, climate, and social welfare. The sea is a climate regulator and a reservoir of biodiversity, a source of food and other resources, a transport route, a cultural asset, and the driving force behind the tourism industry; it is also a natural hazard and, unfortunately, a dumping ground for waste and refuse