The Problem
Past research has focused on the use of macronutrient concentrations as indicators of aquatic ecosystem health. However, more recent findings have suggested that C:N:P stoichiometry may be a more accurate indicator. One hypothesis is that a safe zone of bioavailable C:N:P exists, within which biota can efficiently utilise available nutrients, and thus buffer downstream effects of elevated anthropogenic nutrient loadings. Wide-ranging environmental changes such as recovery from acidification, changing climate, and decreasing N deposition appear to be shifting aquatic ecosystems from N/P excess to C excess. This changing stoichiometry has the potential to alter light regimes and aquatic food webs, pose problems for potable water utilities, and trigger harmful cyanobacterial blooms.
The Fieldwork
Fieldwork will take place on the west coast of Sweden, with a focus on the Anråse catchment, 40km north of Gothenburg. The Anråseån drains a typical mix of forests, lakes and agricultural land, and flows into the Hakefjord in an area that has experienced major seagrass loss since the 1980. The study area also includes the Gårdsjön Research Catchment where experimental studies of acid deposition and long-term monitoring take place. Water samples will be collected from lakes and streams under different land uses (agricultural, mire, forest), and marine samples will be taken from river mouths to the open sea.
The Modelling
Tools will be developed to simulate the fate of dissolved and particulate C, N and P fluxes from the catchment to the fjord environment, by linking the INCA family of catchment models for DOM, N, sediment and P to a hydrodynamic model of water movement (MIKE3 FM) set up for the Hakefjorden and expanded to include new macronutrient process representation.
|
The ProjectDAEMONS is a three year Formas-funded project that commenced in January 2020. It is a holistic, multi-nutrient, source-to-sea project that combines field sampling, lab experiments, and biogeochemical and hydrodynamic modelling, in order to address the effects of multiple environmental changes on aquatic biogeochemistry. The focus of DAEMONS is on finding management solutions to maintaining the optimal C:N:P balance for the beneficial health of the entire aquatic continuum.
The Labwork
For all samples, we will characterise the total, dissolved, organic and inorganic components of N and P, total inorganic and organic carbon, suspended sediments and particulate organic matter. We will also apply high throughput optical characterisation methods (absorbance, fluorescence) to provide low-cost measures of DOM source, molecular composition, and bio- and photo-reactivity. DOM biodegradation will be measured using a Presens high sensitivity non-intrusive optode-based O2 system.
|