Alfred Wegener Institute for Polar and Marine Research
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Gastric carboxylesterases of the edible crab Cancer pagurus (Crustacea, Decapoda) can hydrolyze biodegradable plastics
Get PDFA promising strategy to counteract the progressing plastic pollution of the environment can involve the replacement of persistent plastics with biodegradable materials. Biodegradable polymers are enzymatically degradable by various hydrolytic enzymes. However, these materials can reach the environment in the same way as conventional plastics. Therefore, they are accessible to terrestrial, freshwater, and marine biota. Once ingested by marine organisms, highly active enzymes in their digestive tracts may break down biodegradable compounds. We incubated microparticles of five different biodegradable plastics, based on polylactictic acid (PLA), polybutylene succinate (PBS), polybutylene adipate terephthalate (PBAT) and polyhydroxybutyrate-co-valerate (PHBV), in-vitro with the gastric fluid of the edible crab Cancer pagurus and evaluated the hydrolysis rates by pH Stat titration. A plastic blend of PLA with PBAT showed the highest hydrolysis rate. The enzymes in the gastric fluid of crabs were separated by anion exchange chromatography. Fractions with carboxylesterase activity were identified using fluorescent methylumbelliferyl (MUF)-derivatives. Pooled fractions with high carboxylesterase activity also hydrolyzed a PLA/PBAT plastic blend. Carboxylesterases showed molecular masses of 40e45 kDa as determined by native gel electrophoresis (SDS-PAGE). Our study demonstrated that digestive carboxylesterases in the gastric fluid of C. pagurus exhibit a high potential for hydrolyzing certain biodegradable plastics. Since esterases are common in the digestive tract of organisms, it seems likely that other invertebrates possess the ability to hydrolyze biodegradable plastics
Degradation of a poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) compound in different environments
Get PDFPoly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a promising biodegradable bio-based material, which is designed for a vast range of applications, depending on its composite. This study aims to assess the degradability of a PHBV-based compound under different conditions. The research group followed different methodological approaches and assessed visual and mass changes, mechanical and morphological properties, spectroscopic and structural characterisation, along with thermal behaviour. The Ph-Stat (enzymatic degradation) test and total dry solids (TDS)/total volatile solids (TVS) measurements were carried out. Finally, the team experimentally evaluated the amount of methane and carbon dioxide produced, i.e., the degree of biodegradation under aerobic conditions. According to the results, different types of tests have shown differing effects of environmental conditions on material degradation. In conclusion, this paper provides a summary of the investigations regarding the degradation behaviour of the PHBV-based compound under varying environmental factors. The main strengths of the study lie in its multi-faceted approach, combining assessments of PHBV-based compound degradability under different conditions using various analytical tools, such as visual and mass changes, mechanical and morphological properties, spectroscopic and structural characterization, and thermal behavior. These methods collectively contribute to the robustness and reliability of the undertaken work
Atmospheric destabilization leads to Arctic Ocean winter surface wind intensification
Get PDFThe surface-amplified winter warming over the Arctic Ocean is accompanied by a pronounced intensification of near-surface winds, simulated by climate models and emerging in reanalysis data. Here, the influences of sea-ice decline, wind changes aloft, and atmospheric stability are revisited based on CMIP6 historical and high-emission scenario and ERA5 reanalysis data. Spatial trend patterns suggest that near-surface wind intensification over the inner Arctic Ocean in winter is largely driven by an increasing downward momentum transfer due to a weakening atmospheric stratification. In contrast, a near-surface wind intensification in summer appears to be largely driven by accelerating winds aloft, amplified in a high-emission future by decreasing surface roughness due to sea-ice decline. In both seasons, differences in near-surface wind-speed trends are closely linked to atmospheric stability trends. Models suggest that by 2100 the lower troposphere may become as unstable in winter as in summer, implying a fundamental regime shift of the Arctic winter boundary layer
Spatial distribution of small microplastics in the Norwegian Coastal Current
Get PDFHigh concentrations of microplastic (MP) particles have been reported in the Arctic Ocean. However, studies on the high-resolution lateral and vertical transport of MPs from the European waters to the Arctic are still scarce. Here, we provide information about the concentrations and compositions of MPs in surface, subsurface, and deeper waters (300 μm), and overall, SMPs 80 % of all detected MPs. However, no statistically significant geographical patterns were observed in SMP concentrations in surface/subsurface seawaters between the six sampling transects, suggesting a relatively homogeneous horizontal distribution of SMPs in the upper ocean within the NCC/Norwegian Atlantic Current (NwAC) interface. The Lagrangian particle dispersal simulation model further enabled us to assess the large-scale transport of MPs from the Northern European waters to the Arctic
Evaluating the global ocean biogeochemistry models used in the Global Carbon Budget with the International Ocean Model Benchmarking (IOMB) System
Get PDFCircumarctic land cover diversity considering wetness gradients
Get PDFLand cover heterogeneity information considering soil wetness across the entire Arctic tundra is of interest for a wide range of applications targeting climate change impacts and ecological research questions. Patterns are potentially linked to permafrost degradation and affect carbon fluxes. First, a land cover unit retrieval scheme which provides unprecedented detail by fusion of satellite data using Sentinel-1 (synthetic aperture radar) and Sentinel-2 (multispectral) was adapted. Patterns of lakes, wetlands, general soil moisture conditions and vegetation physiognomy are interpreted at 10 m nominal resolution. Units with similar patterns were identified with a k-means approach and documented through statistics derived from comprehensive in situ records for soils and vegetation (more than 3500 samples). The result goes beyond the capability of existing land cover maps which have deficiencies in spatial resolution, thematic content and accuracy, although landscape heterogeneity related to moisture gradients cannot be fully resolved at 10 m. Wetness gradients were assessed, and measures for landscape heterogeneity were derived north of the treeline. About 40 % of the area north of the treeline falls into three units of dry types with limited shrub growth. Wetter regions have higher land cover diversity than drier regions. An area of 66 % of the analysed Arctic landscape is highly heterogeneous with respect to wetness at a 1 km scale (representative scale of frequently used regional land cover and permafrost modelling products). Wetland areas cover 9 % and moist tundra types 32 %, which is of relevance for methane flux upscaling
Seasonality of spectral radiative fluxes and optical properties of Arctic sea ice during the spring–summer transition
Get PDFThe reflection, absorption, and transmittance of shortwave solar radiation by sea ice play crucial roles in
physical and biological processes in the ice-covered Arctic Ocean and atmosphere. These sea-ice optical
properties, particularly during the melt season, significantly impact energy fluxes within and the total
energy budget of the coupled atmosphere-ice-ocean system. We analyzed data from autonomous drifting
stations to investigate the seasonal evolution of the spectral albedo, transmittance, and absorptivity for
different sea-ice, snow, and surface conditions measured during the MOSAiC expedition in 2019–2020. The
spatial variability of these properties was small during spring and increased strongly after melt onset on May
26, 2020, when liquid water content on the surface increased, largely accounting for the enhanced variability.
The temporal evolution of surface albedo and sea-ice transmittance was mostly event-driven, thus containing
episodic elements. Melt ponds reduced the local surface albedo by 31%–45%. Over the melting season, single
ponding events increased the energy deposition of the sea ice by 35% compared to adjacent bare ice. Thus,
single melt ponds may impact the summer energy budget as much as seasonal evolution over 1 month.
Absorptivity and transmittance showed strong temporal and spatial variabilities independently of surface
conditions, possibly due to the different internal sea-ice properties and under-ice biological processes. The
differences in seasonal evolution shown for different sea-ice conditions strongly impacted the partitioning
of shortwave solar radiation.This study shows that the formation and development of melt ponds, in reducing
albedo by a third of bare ice sites, can notably increase the total summer heat deposition.The vastly different
seasonal evolutions, different sea-ice conditions, and timing and duration of ponding events need to be
considered when comparing local in-situ observations with large-scale satellite remote sensing datasets,
which we suggest can help to improve numerical models
Monitoring plankton and hydrography in Potter Cove: observing a changing system during 30 years
Get PDFAntarctic ecosystems are experiencing significant environmental changes, leading to shifts in hydrography, plankton abundance, and community composition, potentially affecting the entire food web. Since the early 1990s, the Coastal Ecology Programme of the Argentinian Antarctic Institute, in collaboration with the Alfred Wegener Institute from Bremerhaven, Germany, has been monitoring coastal hydrography and plankton dynamics. Over nearly 30 years, observations at Potter Cove (25 de Mayo/King George Island, South Shetlands) revealed notable transformations, such as the retreat of the surrounding Fourcade Glacier, and its evolution from a tidal to a land-terminated glacier in 2016, coinciding with a consistent rise in temperature. In addition, Potter Cove phytoplankton, characterized by sparse abundances and occasional blooms during colder seasons in the decades between early 1990’s and 2010, evidenced a shift occurring post-2010, marked by more frequent phytoplankton blooms. However, in warmer-than-average years of the last decade, the plankton community composition skewed toward nanosized phytoplankton, including species typical of Subantarctic regions. It was demonstrated in summer 2020 during two marine heatwave events through in situ monitoring of plankton community. These findings underscore the necessity for ongoing monitoring and research to comprehend the implications of a warming climate on Antarctic ecosystems. In this sense, in January 2024, as part of the ROMA (Argentinian Network for Observations of Coastal Marine Systems), an automated coastal station was deployed in Potter Cove to gather hydrographic and meteorological data. Similarly, a station with additional sensors for chlorophyll and oxygen concentrations has been operational since 2023 in the Beagle Channel, a Subantarctic coastal area, augmenting our understanding of oceanic changes under global warming scenarios. Next year two Lander moorings will be deployed at 30 m depth in both sites, to collect data on salinity, temperature, dissolved oxygen, chlorophyll and currents. These initiatives are pivotal for bridging data and knowledge gaps and advancing our comprehension of oceanic shifts
How are the impacts of multiple anthropogenic drivers considered in marine ecosystem service research? A systematic literature review
Get PDFIn recent decades, great research efforts have been made to understand how specific anthropogenic drivers impact coastal marine ecosystems and their services. Nevertheless, we still lack a synthesis of the existing knowledge on single and multiple anthropogenic drivers impacts to coastal marine systems, which is necessary to guide future work. The objective of this paper is to assess the current knowledge on the impacts of anthropogenic drivers and their interactions on coastal marine ecosystem services, with emphasis on abiotic drivers as dissolved nutrients (eutrophication or de-eutrophication), temperature (warming), pH (acidification) and oxygen (hypoxia). We performed a systematic review of the literature consisting of 164 papers using the PRISMA method (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). We only include English-written papers, we exclude non-English papers to avoid potential errors in representing or interpreting scientific information due to language limitations among the authors. The results show that coastal marine ecosystem service research has largely focused on single drivers, while multiple driver assessments are less common. Assessments partially integrate multiple driver complexity, but they do not consider (1) relations and feedbacks between drivers; 2() social processes dynamics; and (3) temporal and spatial scales. Synthesis and applications. We have reviewed the current scientific knowledge on how human drivers affect coastal marine ecosystem services. We found that understanding the combined effects of different drivers and considering various time and space scales is still a pending issue. Ignoring multiple drivers, their interactions and time and space scales limits our understanding of reality, and results in high levels of uncertainty. This affects policies and actions, as they rely on uncertain information. Thus, incomplete knowledge leads to poor management of coastal ecosystem services. To improve this, we propose research framework to better consider multiple drivers and time and space factors
