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MARLAN: Plymouth Marine Laboratory’s Marine Artificial Light at Night Research Facility
Get PDFThis document provides technical guidance about, and design description of, the Plymouth Marine Laboratory’s Marine Artificial Light At Night Research Facility (MARLAN), a bespoke seawater aquarium facility dedicated to the study of light pollution in the marine environment
Multidecadal changes in biology influence the variability of the North Atlantic carbon sink
Get PDFThe North Atlantic Ocean is the most intense marine sink for anthropogenic carbon dioxide (CO2)in the world’s oceans, showing high variability and substantial changes over recent decades. However, the contribution of biology to the variability and trend of this sink is poorly understood. Here we use in situ plankton measurements, alongside observation-based sea surface CO2 data from 1982 to 2020, to investigate the biological influence on the CO2 sink. Our results demonstrate that long term variability in the CO2 sink in the North Atlantic is associated with changes in
phytoplankton abundance and community structure. These data show that within the subpolar regions of the North Atlantic, phytoplankton biomass is increasing, while a decrease is observed in the subtropics, which supports model predictions of climate-driven changes in productivity. These biomass trends are synchronous with increasing temperature, changes in mixing and an increasing uptake of atmospheric CO2 in the subpolar North Atlantic. Our results highlight that phytoplankton play a significant role in the variability as well as the trends of the CO2 uptake from the atmosphere over recent decades
Seasonality and interannual variability of copepods in the Western English Channel, Celtic Sea, Bay of Biscay, and Cantabrian Sea with a special emphasis to Calanus helgolandicus and Acartia clausi
No full textA total of five mesozooplankton time series data sets were assembled to compare the seasonal and interannual patterns of abundance of calanoid copepods in the Western English Channel (Station L4), Celtic Sea, Bay of Biscay (Continuous Plankton Recorder), and the Cantabrian Sea (RADIALES time series, Santander, St-4 and St-6) from January 1992 to December 1999. A strong seasonal component in taxonomic composition was detected at the locations considered. There was also a strong latitudinal effect on diversity at each location, southernmost locations being more diverse. The seasonal dynamics and year-to-year variability of two copepod species: Calanus helgolandicus and Acartia clausi were studied in detail. A latitudinal pattern in the seasonal cycles of both copepod species was observed. The peaks of both occur earlier in spring in the warmer southern region and move northwards, consistent with the temperature regimes at each location, supporting the broad concept that species occupy a thermal niche in time as well as in space. There was a strong degree of interannual variability between sites and between species. No clear trends, but some coherent events among data sets, reveal a regional response to environmental forcing factors. Correlations suggest possible connections with environmental indices like the North Atlantic Oscillation and the Gulf Stream North Wall index. There was a positive correlation between the NAO and the abundance of C. helgolandicus at station L4 off Plymouth; however, the relationship in the Celtic Sea and Bay of Biscay was opposite to that expected based on previous results. Despite the differences in the sampling techniques used within each dataset, the results are comparable and coherent in terms of taxonomic composition and the seasonal and interannual patterns detected
Variations of microbial communities and substrate regimes in the eastern Fram Strait between summer and fall
Get PDFSeasonal variations in day length and temperature, in combination with dynamic factors such as advection from the North Atlantic, influence primary production and the microbial loop in the Fram Strait. Here, we investigated the seasonal variability of biopolymers, microbial abundance and microbial composition within the upper 100 m during summer and fall. Flow cytometry revealed a shift in the autotrophic community from picoeukaryotes dominating in summer to a 34-fold increase of Synechococcus by fall. Furthermore, a significant decline in biopolymers concentrations covaried with increasing microbial diversity based on 16S rRNA gene sequencing along with a community shift towards fewer polymer-degrading genera in fall. The seasonal succession in the biopolymer pool and microbes indicates distinct metabolic regimes, with a higher relative abundance of polysaccharide-degrading genera in summer and a higher relative abundance of common taxa in fall. The parallel analysis of DOM and microbial diversity provides an important baseline for microbe–substrate relationships over the seasonal cycle in the Arctic Ocean
Assuring the integrity of offshore carbon dioxide storage
Get PDFCarbon capture and storage is a key mitigation strategy proposed for keeping the global temperature rise below
1.5 ◦C. Offshore storage can provide up to 13% of the global CO2 reduction required to achieve the Intergovernmental Panel on Climate Change goals. The public must be assured that potential leakages from storage reservoirs can be detected and that therefore the CO2 is safely contained. We conducted a controlled release of 675 kg CO2 within sediments at 120 m water depth, to simulate a leak and test novel detection, quantification and attribution approaches. We show that even at a very low release rate (6 kg day− 1), CO2 can be detected within sediments and in the water column. Alongside detection we show the fluxes of both dissolved and gaseous CO2 can be quantified. The CO2 source was verified using natural and added tracers. The experiment demonstrates that existing technologies and techniques can detect, attribute and quantify any escape of CO2 from sub-seabed reservoirs as required for public assurance, regulatory oversight and emissions trading schemes
Influence of short and long term processes on SAR11 communities in open ocean and coastal systems
Get PDFSAR11 bacteria dominate the surface ocean and are major players in converting fixed carbon back to atmospheric carbon dioxide. The SAR11 clade is comprised of niche-specialized ecotypes that display distinctive spatiotemporal transitions. We analyzed SAR11 ecotype seasonality in two long-term 16S rRNA amplicon time series representing different North Atlantic regimes: the Sargasso Sea (subtropical ocean-gyre; BATS) and the temperate coastal Western English Channel (WEC). Using phylogenetically resolved amplicon sequence variants (ASVs), we evaluated seasonal environmental constraints on SAR11 ecotype periodicity. Despite large differences in temperature and nutrient availability between the two sites, at both SAR11 succession was defined by summer and winter clusters
of ASVs. The summer cluster was dominated by ecotype Ia.3 in both sites. Winter clusters were dominated by ecotypes Ib and IIa.A at BATS and Ia.1 and IIa.B at WEC. A 2-year weekly analysis within the WEC time series showed that the response of SAR11 communities to short-term environmental fluctuations was variable. In 2016, community shifts were abrupt and synchronized to environmental shifts. However, in 2015, changes were gradual and decoupled from environmental fluctuations, likely due to increased mixing from strong winds. We demonstrate that interannual weather variability disturb the pace of SAR11 seasonal progression
Climate change on sea currents is not expected to alter contemporary migration routes of loggerhead sea turtles
Get PDFFor marine species, traveling with the current potentially reduces energetic costs. Still, the extent to which organisms adjust routes to follow current flow remains an open question. Moreover, the extent to which climate change is altering sea currents, and in turn species migration routes, remains unknown, representing a major challenge to spatial ecology and conservation efforts.We developed an approach to assess the extent to which projected optimal paths and corridors overlap with the observed migration routes of loggerhead sea turtles (Caretta caretta), minimizing exposure to opposing sea currents. To illustrate this approach, we used migratory tracks of the species traveling between breeding and foraging areas in the Mediterranean Sea. We calculated the energetic costs to sea turtles based on actual tracks and corresponding optimal paths. We also explored whether projected changes in ocean currents, driven by climate change, would alter the spatial patterns of optimal routes.The energetic cost of observed tracks was, on average, 1.25 times higher than that of corresponding optimal paths. While optimal corridors differed spatially to observed corridors used by loggerheads, some positive correlations still existed for three cases ( 0.43, 0.42, 0.30). Climate change projections showed no significant change to the migratory movement of sea turtles, as corridors for different climatic conditions overlapped by at least 70%.Our results show that loggerheads do not explicitly take advantage of ocean currents to facilitate long distance migrations and reduce energetic demands. The contemporary and future migration routes are characterized by similar energetic demands and together with their strong spatial overlap suggest that climate change is expected to minimally alter the species migration routes in the future. The approach presented here could be applied to different spatial scales and marine taxa, allowing possible mechanisms between sea currents (or other environmental characteristics) and species movements to be elucidated
Diving into the vertical dimension of elasmobranch movement ecology
Get PDFKnowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Substantial vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps toward incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasizing the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements
Semantic Music Production: A Meta-Study
Get PDFThis paper presents a systematic review of semantic music production, including a meta-analysis of three studies into how individuals use words to describe audio effects within music production. Each study followed different methodologies and stimuli. The SAFE project created audio effect plug-ins that allowed users to report suitable words to describe the perceived result. SocialFX crowdsourced a large data set of how non-professionals described the change that resulted from an effect applied to an audio sample. The Mix Evaluation Data Set performed a series of controlled studies in which students used natural language to comment extensively on the content of different mixes of the same groups of songs. The data sets provided 40,411 audio examples and 7,221 unique word descriptors from 1,646 participants. Analysis showed strong correlations between various audio features, effect parameter settings, and semantic descriptors. Meta-analysis not only revealed consistent use of descriptors among the data sets but also showed key differences that likely resulted from the different participant groups and tasks. To the authors' knowledge, this represents the first meta-study and the largest-ever analysis of music production semantics
Identifying the biological control of the annual and multi-year variations in South Atlantic air–sea CO2 flux
Get PDFThe accumulation of anthropogenic CO2 emissions in the atmosphere has been buffered by the absorption of CO2 by the global ocean, which acts as a net CO2 sink. The CO2 flux between the atmosphere and the ocean, which collectively results in the oceanic carbon sink, is spatially and temporally variable, and fully understanding the driving mechanisms behind this flux is key to assessing how the sink may change in the future. In this study a time series decomposition analysis was applied to satellite observations to determine the drivers that control the sea–air difference of CO2 partial pressure (ΔpCO2) and the CO2 flux on seasonal and inter-annual timescales in the South Atlantic Ocean. Linear trends in ΔpCO2 and the CO2 flux were calculated to identify key areas of change.
Seasonally, changes in both the ΔpCO2 and CO2 flux were dominated by sea surface temperature (SST) in the subtropics (north of 40∘ S) and were correlated with biological processes in the subpolar regions (south of 40∘ S). In the equatorial Atlantic, analysis of the data indicated that biological processes are likely a key driver as a response to upwelling and riverine inputs. These results highlighted that seasonally ΔpCO2 can act as an indicator to identify drivers of the CO2 flux. Inter-annually, the SST and biological contributions to the CO2 flux in the subtropics were correlated with the multivariate El Niño–Southern Oscillation (ENSO) index (MEI), which leads to a weaker (stronger) CO2 sink in El Niño (La Niña) years.
The 16-year time series identified significant trends in ΔpCO2 and CO2 flux; however, these trends were not always consistent in spatial extent. Therefore, predicting the oceanic response to climate change requires the examination of CO2 flux rather than ΔpCO2. Positive CO2 flux trends (weakening sink for atmospheric CO2) were identified within the Benguela upwelling system, consistent with increased upwelling and wind speeds. Negative trends in the CO2 flux (intensifying sink for atmospheric CO2) offshore into the South Atlantic gyre were consistent with an increase in the export of nutrients from mesoscale features, which drives the biological drawdown of CO2. These multi-year trends in the CO2 flux indicate that the biological contribution to changes in the air–sea CO2 flux cannot be overlooked when scaling up to estimates of the global ocean carbon sink