Land-cover, climate and fjord morphology drive differences in organic matter and nutrient dynamics in two contrasting northern river-fjord systems

Climate and land-use changes are leading to impacts on individual ecosystems as well as shifts in transfer dynamics between interconnected systems. At the land-ocean interface, changes in riverine inputs of organic matter (OM) and nutrients have the potential to lead to shifts in coastal carbon and nutrient cycling with consequences for ecosystem structure and function. In this study, we assess OM and nutrient dynamics for two contrasting Norwegian river-to-fjord systems: a boreal system with a forested catchment draining into a narrow fjord (‘narrow boreal system’), and a subarctic system where lowland forests and mountainous regions drain into a broad fjord (‘broad subarctic system’). We characterized seasonal organic carbon and nutrient concentrations and DOM absorption properties for samples collected along transects from river to outer fjord during 2015/2016. While differences in catchment properties drove contrasts in river chemistry between the two study rivers, fjord morphology and hydrodynamics as well as dissolved organic carbon (DOC) and nutrient concentrations in marine receiving waters predicted water-chemistry patterns along the transect. The narrow boreal system, with high riverine DOC and nutrient concentrations, was structured mainly by a horizontal salinity gradient from river to outer fjord, with limited impact of seasonality. In contrast, the broad subarctic system tended to be dominated by vertical salinity stratification, with strong between-date differences in surface water salinity linked to seasonality in river discharge. These dynamics were also reflected in the strong horizontal gradients in DOC, nutrients and DOM properties in the narrow boreal system, in contrast to the broad subarctic system, where strong seasonality paired with a lack of strong contrast between riverine and marine concentrations of DOC and most nutrients led to an uncoupling between salinity and other water chemistry variables. In the narrow boreal system, terrestrial OM dominated both the particulate and dissolved OM pools, while OM in the broad subarctic system was derived primarily from marine phytoplankton. Non-linear declines in NO3 + NO2 were observed consistently in the boreal system and during the productive spring season in the subarctic system, suggesting biological uptake and a potentially important role of these rivers as sources of bioavailable N to coastal ecosystems. The results from these two case studies highlight the complex and interacting effects of catchment land-cover, river water chemistry and discharge, fjord morphometry and hydrodynamics in structuring the transport, fate and potential impacts of terrestrially-derived nutrients and organic matter in northern coastal environments

Nuisance growth of Juncus bulbosus: the roles of genetics and environmental drivers tested in a large-scale survey

1. Invasive species can transform aquatic ecosystems, and the nuisance growth of the freshwater macrophyte Juncus bulbosus has become a problem in many lakes and rivers in northern Europe. It affects biodiversity strongly and conflicts with human uses, not least compromising the generation of hydroelectricity. The causes of the proliferation of these massive stands of J. bulbosus are not finally resolved, however. 2. In this study, a wide range of catchment, lake and sediment parameters (n = 34) were assessed for 139 lakes in Southern Norway, with the aim of explaining the presence or absence of J. bulbosus and to assess potential drivers behind its prolific growth. 3. Juncus bulbosus was more often present in lakes with lower pH and phosphate concentrations, and a higher element ratio of dissolved inorganic nitrogen (DIN) to total phosphorus (DIN : TotP). 4. Despite the many parameters measured across substantial environmental gradients, none explained nuisance growth. Genetic screening (amplified fragment length polymorphism fingerprinting) of plants from a subset of lakes and additional river sites also showed no genetic differences between the various growth forms. A macrophyte trophic index, however, suggested that the most problematic growth occurred in the most oligotrophic lakes. 5. The lack of consistent patterns may reflect either factors not assessed in our survey, or that the current extension of stands represents a gradual cumulative response over time, not characterised effectively in our snapshot survey. Nevertheless, we can now exclude some putative causes of nuisance growth, including in particular genetics and N‐deposition.acceptedVersio

Long-term annual and spatial variation of polygyny in the white-throated dipper (Cinclus cinclus)

Mating strategies are key components in the fitness of organisms, and notably in birds the occurrence of monogamy versus polygyny has attracted wide interest. We address this by a very comprehensive dataset (2899 breeding events spanning the years 1978–2019) of the white-throated dipper Cinclus cinclus. Though the mating system of this species has been regarded as generally monogamous, we find that 7% of all breeding events were performed by polygynous males (approximately 15% of all pairs). The fraction of polygyny has been stable over the entire study period irrespective of population size. The assumption that polygyny is most common at low population density was not supported. Surprisingly, there was no difference between polygynous and monogamous males with regard to the quality of the territories they inhabited, ranked according to their overall frequency of use. The most common age group, first-year breeders, dominated among monogamous males, while among polygynous males second-year breeders were most common, followed by third and first-year breeders. The primary females were in general older than females mated to monogamous males, also when controlled for their general frequency in the population. The majority of the two females mated to a polygynous male, bred in the vicinity of each other. The probability for a male to be involved in polygyny more than once, was significantly higher than by chance, suggesting phenotypic quality differences among males. frequency of polygyny, mating strategy, monogamous, territory quality, white-throated dipper Behavioural ecology, Evolutionary ecology, Population ecologypublishedVersio

Environmental impacts — Lake ecosystems

The North Sea region contains a vast number of lakes; from shallow, highly eutrophic water bodies in agricultural areas to deep, oligotrophic systems in pristine high-latitude or high-altitude areas. These freshwaters and the biota they contain are highly vulnerable to climate change. As largely closed systems, lakes are ideally suited to studying climate-induced effects via changes in ice cover, hydrology and temperature, as well as via biological communities (phenology, species and size distribution, food-web dynamics, life-history traits, growth and respiration, nutrient dynamics and ecosystem metabolism). This chapter focuses on change in natural lakes and on parameters for which their climate-driven responses have major impacts on ecosystem properties such as productivity, community composition, metabolism and biodiversity. It also points to the importance of addressing different temporal scales and variability in driving and response variables along with threshold-driven responses to environmental forces. Exceedance of critical thresholds may result in abrupt changes in particular elements of an ecosystem. Modelling climate-driven physical responses like ice-cover duration, stratification periods and thermal profiles in lakes have shown major advances, and the chapter provide recent achievements in this field for northern lakes. Finally, there is a tentative summary of the level of certainty for key climatic impacts on freshwater ecosystems. Wherever possible, data and examples are drawn from the North Sea region

Do DOM quality and origin affect the uptake and accumulation of lipid-soluble contaminants in coastal filter feeders? An experimental simulation of teflubenzuron exposure to blue mussels

The increased export of terrestrial dissolved organic matter (terrDOM) to coastal marine ecosystems may affect local filter feeders and the local food web via the altered uptake of organic material and associated contaminants. To compare terrDOM to marine DOM (marDOM) as contaminant vectors to coastal biota, we exposed blue mussels (Mytilus sp.) to the different DOM types in combination with teflubenzuron, a widely applied lipophilic aquaculture medicine targeting salmon lice (Lepeophtheirus salmonis). A 16-day exposure of the blue mussels to DOM and teflubenzuron was followed by a depuration phase of 20 days without teflubenzuron. We calculated teflubenzuron adsorption rates and bioaccumulation factors (BAF) using a Bayesian model, expecting teflubenzuron uptake to be greater with terrDOM than marDOM due to the higher prevalence of large amphipathic humic acids in terrDOM. Humic acids have strong absorption properties and are able to envelope lipophilic molecules. Thus, humic acids can function as an efficient contaminant vector when taken up by filter feeders. Although there were varying degrees of overlap, the mussels tended to accumulate higher amounts of teflubenzuron in the DOM treatments than in the seawater control (bioaccumulation factor [BAF] in seawater: median 106 L/kg; 2.5 %–97.5 % percentile: 69–160 L/kg). Contrary to expectations, mussels exposed to marDOM showed a trend toward more bioaccumulation of teflubenzuron than those exposed to terrDOM (BAF marine 144 L/kg; 102–221 L/kg versus BAF terrestrial: 121 L/kg; 82–186 L/kg). The highest teflubenzuron accumulation was observed with the 50:50 mixture of marDOM and terrDOM (BAF mix: 165 L/kg; 117–244 L/kg). The slight difference in DOM-type accumulation rates observed in this experiment—especially the accumulation rate of terrDOM compared to that of the seawater-only treatment type—was not considered environmentally relevant. Further studies are necessary to see if the observed trends transfer to complex environmental systems.publishedVersio

Increased risk of phosphorus limitation at higher temperatures for Daphnia magna

Invertebrate herbivores frequently face growth rate constraints due to their high demands for phosphorus (P) and nitrogen (N). Temperature is a key modulator of growth rate, yet the interaction between temperature and P limitation on somatic growth rate is scarcely known. To investigate this interaction, we conducted a study on the somatic growth rate (SGR) of the cladoceran Daphnia magna, known to be susceptible to P-limitation. We determined the SGR across a broad range of dietary P content of algae (carbon (C):P ratios (125–790), and at different temperatures (10–25°C). There was a strong impact of both temperature and C:P ratio on the SGR of D. magna, and also a significant interaction between both factors was revealed. The negative effect of dietary C:P on growth rate was reduced with decreased temperature. We found no evidence of P limitation at lowest temperature, suggesting that enzyme kinetics or other measures of food quality overrides the demands for P to RNA and protein synthesis at low temperatures. These findings also indicate an increased risk of P limitation and thus reduced growth efficiency at high temperatures

Knowledge-driven actions: Transforming higher education for global sustainability

Universities and, more broadly, higher education institutions (HEIs), need to use the knowledge they produce and their education of new professionals, to help solve some of the world´s greatest problems, as addressed by the Sustainable Development Goals (SDGs) set out by the United Nations (UN). Humanity is facing unprecedented challenges, most strikingly so in relation to climate change and loss of nature and biodiversity, as well as inequality, health, the economy, and a suite of issues related to the 2030 Agenda. Given this new reality in which the future of humans, along with other species, is at stake, it is time for HEIs and their stakeholders to systematically rethink their role in society and their key missions, and reflect on how they can serve as catalysts for a rapid, urgently needed and fair transition towards sustainability. The complexity of the issues at stake means that solutions should be part of a radical agenda that calls for new alliances and new incentives. It is also time for HEIs to make sustainability and SDG literacy core requisites for all faculty members and students. Sustainability education should bring students into contact with real-world problems an immersive experiences. Appreciating the greater good of both people and planet, and contributing to values beyond mere monetary gain will further enthuse and inspire students and faculty mentors alike. Ultimately, the educational culture at universities and HEIs needs to encourage students to learn via experimentation and critical thinking from multiple perspectives. This report is undoubtedly about the SDGs; however, it is important to realize that these will expire in 2030. We thus strongly recommend that HEIs, while being a part of that agenda, should also look ahead – not only to implementing the SDGs, but also to being intensively involved in crafting the next steps and goals beyond 2030. A long-term perspective needs to be adopted for both HEI activities and policies. The call this report makes is for universities and HEIs to play an active part in an agenda that has the consensus of 193 countries and aims to resolve some of the world’s most pressing problems, as stated in the 17 SDGs. The challenge is for HEIs to embrace the 2030 Agenda, because if they do not it will be difficult, if not impossible, to achieve the SDGs. The SDGs represent a unifying challenge for all universities and HEIs, and this must be reflected in plans and actions for research, education and outreach. HEIs have played a crucial role as bringers of societal enlightenment and change over the centuries, maintaining their role as free and critical institutions while also – to varying degrees – aiming to perform a service within societies. It is essential to maintain and encourage these important roles and enable HEIs to combine their traditions of critical thinking with problem-solving activities, while also adjusting their role in the light of societal changes. The future of humanity and our planet is under threat, and the need for critical thinking and societal change is therefore more pressing than ever. HEIs should inspire societal change when necessary, taking a leading role in the transitions necessary for humankind and emphasizing that the need for change is immediate. This also implies that HEIs should think critically about their own practices, curricula and research, and about how to motivate their employees, students and society at large to do the same

Microplastics; occurrence, levels and implications for environment and human health related to food. Scientific opinion of the Scientific Steering Committee of the Norwegian Scientific Committee for Food and Environment

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Microplastics; occurrence, levels and implications for environment and human health related to food. Opinion of the Steering Committee of the Norwegian Scientific Committee for Food and Environment

Report from the Norwegian Scientific Committee for Food Safety (VKM) 2019:16. Microplastics; occurrence, levels and implications for environment and human health related to food. Opinion of the Steering Committee of the Norwegian Scientific Committee for Food and Environment. Source at https://www.vkm.no/. The steering committee of VKM has self-initiated a mandate for an opinion on microplastics based on recently published international and/or national reports complemented with literature from December 2016 to February 2019. The mandate requested a summary of the state of knowledge on the presence of microplastics in the environment and the implications for the ecosystem, terrestrial and aquatic organisms, food production and human health. An overview of main national and international ongoing initiatives was also requested, and highlighting of data gaps where specific Norwegian data was needed

Food and chemical substances relevant for monitoring. Report from the Scientific Steering Committee of the Norwegian Scientific Committee for Food and Environment.

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