Governance hurdles for expansion of low trophic mariculture production in Sweden.

The study examines the governance of low trophic species mariculture (LTM) using Sweden as a case study. LTM, involving species such as seaweeds and mollusks, offers ecosystem services and nutritious foods. Despite its potential to contribute to blue growth and Sustainable Development Goals, LTM development in the EU and OECD countries has stagnated. A framework for mapping governance elements (institutions, structures, and processes) and analyzing governance objective (effective, equitable, responsive, and robust) was combined with surveys addressed to the private entrepreneurs in the sector. Analysis reveals ineffective institutions due to lack of updated legislation and guidance, resulting in ambiguous interpretations. Governance structures include multiple decision-making bodies without a clear coordination agency. Licensing processes were lengthy and costly for the private entrepreneurs, and the outcomes were uncertain. To support Sweden's blue bioeconomy, LTM governance requires policy integration, clearer direction, coordinated decision-making, and mechanisms for conflict resolution and learning.

Cost-benefit analysis of beach-cast harvest: Closing land-marine nutrient loops in the Baltic Sea region.

Harvesting beach-cast can help mitigate marine eutrophication by closing land-marine nutrient loops and provide a blue biomass raw material for the bioeconomy. Cost-benefit analysis was applied to harvest activities during 2009-2018 on the island of Gotland in the Baltic Sea, highlighting benefits such as nutrient removal from the marine system and improved recreational opportunities as well as costs of using inputs necessary for harvest. The results indicate that the activities entailed a net gain to society, lending substance to continued funding for harvests on Gotland and assessments of upscaling of harvest activities to other areas in Sweden and elsewhere. The lessons learnt from the considerable harvest experience on Gotland should be utilized for developing concrete guidelines for carrying out sustainable harvest practice, paying due attention to local conditions but also to what can be generalized to a wider national and international context.

Browning of freshwaters: Consequences to ecosystem services, underlying drivers, and potential mitigation measures.

Browning of surface waters, as a result of increasing dissolved organic carbon and iron concentrations, is a widespread phenomenon with implications to the structure and function of aquatic ecosystems. In this article, we provide an overview of the consequences of browning in relation to ecosystem services, outline what the underlying drivers and mechanisms of browning are, and specifically focus on exploring potential mitigation measures to locally counteract browning. These topical concepts are discussed with a focus on Scandinavia, but are of relevance also to other regions. Browning is of environmental concern as it leads to, e.g., increasing costs and risks for drinking water production, and reduced fish production in lakes by limiting light penetration. While climate change, recovery from acidification, and land-use change are all likely factors contributing to the observed browning, managing the land use in the hydrologically connected parts of the landscape may be the most feasible way to counteract browning of natural waters.

Greenhouse gas production in a pond sediment: effects of temperature, nitrate, acetate and season.

In this paper we investigate the impact of nitrate (NO(3)(-)) concentration and temperature on the production of carbon dioxide (CO(2)), methane (CH(4)) and nitrous oxide (N(2)O). We studied sediment collected during spring, summer and autumn from a constructed pond in South Sweden. Homogenised sediment samples were dark incubated in vitro under N(2) atmosphere at 13 degrees C and 20 degrees C after addition of five NO(3)(-) concentrations, between 0 and 16 mg NO(3)(-)-N per litre. We found higher net production of N(2)O and CO(2) at the higher temperature. Moreover, increased NO(3)(-) concentrations had strong positive impact on the N(2)O concentration, but no effect on CH(4) and CO(2) production. The lack of response in CO(2) is suggested to be due to the use of alternative oxidants as electron acceptors. Interaction between NO(3)(-) and temperature suggests a further increase of N(2)O net production when both NO(3)(-) and temperature are high. Our interpretation of the CH(4) data is that at high concentrations of NO(3)(-) temperature is of less importance for CH(4) production. We also found that at 13 degrees C CH(4) production was substrate limited and that the addition of acetate increased CH(4) as well as CO(2) production. There was a seasonal effect on gas production potential, with more CH(4) and N(2)O produced in spring than in summer. Re-calculation of the gas concentrations into global warming potential (GWP) units (i.e. CO(2), CH(4), and N(2)O transferred to CO(2) equivalents) shows that GWP increases with temperature. However, under environmental conditions generally occurring in South Swedish ponds, i.e. low temperature and high NO(3)(-) concentration during spring and high temperature and low NO(3)(-) concentration during summer, NO(3)(-) concentration is of minor importance.

Consequences of intensive forest harvesting on the recovery of Swedish lakes from acidification and on critical load exceedances.

Across much of the northern hemisphere, lakes are at risk of re-acidification due to incomplete recovery from historical acidification and pressures associated with more intensive forest biomass harvesting. Critical load (CL) calculations aimed at estimating the amount of pollutants an ecosystem can receive without suffering adverse consequences are dependent on these factors. Here, we present a modelling study of the potential effects of intensified forest harvesting on re-acidification of a set of 3239 Swedish lakes based on scenarios with varying intensities of forest biomass harvest and acid deposition. There is some evidence that forestry would have caused a certain level of acidification even if deposition remained at 1860 levels. We show that all plausible harvest scenarios delay recovery due to increased rates of base cation removal. Scenario results were used to estimate critical loads for the entire population of lakes in Sweden. The forestry intensity included in critical load calculations is a political decision. After scaling calculations to the national level, it was apparent that a high but plausible forest harvest intensity would lead to an increase in the area of CL exceedances and that even after significant reductions in forest harvest intensity, there would still be areas with CL exceedances. Our results show that forest harvest intensity and regional environmental change must be carefully considered in future CL calculations.

Bacterial and fungal colonization and decomposition of submerged plant litter: consequences for biogenic silica dissolution.

We studied bacterial and fungal colonization of submerged plant litter, using a known Si-accumulator (Equisetum arvense), in experimental microcosms during one month. We specifically addressed the microbial decomposer role concerning biogenic silica (bSiO2) dissolution from the degrading litter. To vary the rates and level of microbial colonization, the litter was combined with a range of mineral nitrogen (N) and phosphorous (P) supplements. Overall microbial growth on plant litter increased with higher levels of N and P. There was a tendency for higher relative bacterial than fungal stimulation with higher nutrient levels. Differences in microbial colonization of litter between treatments allowed us to test how Si remineralization from plants was influenced by microbial litter decomposition. Contrary to previous results and expectations, we observed a general reduction in Si release from plant litter colonized by a microbial community, compared with sterile control treatments. This suggested that microbial growth resulted in a reduction of dissolved Si concentrations, and we discuss candidate mechanisms to explain this outcome. Hence, our results imply that the microbial role in plant litter associated Si turnover is different from that commonly assumed based on bSiO2 dissolution studies in aquatic ecosystems.