Transfer of Nutrients and Organic Matter from Land to Coastal Waters
Since the early 2000s various teams in Ocean Sciences at Bangor University have been part of large international consortia to investigate the effect of organic matter on bacteria populations in waters along the land-estuary-sea continuum. This work has been conducted locally in the River Conwy and more lately in much large river systems in Finland (Fleming-Lehtinen et al. 2015; Räike et al. 2016). Fundamental to this work has been the chemical characterization of the organic matter, and then showing how changes in organic matter properties results in changes in the bacteria populations (Kaartokallio et al. 2016).
Through this work we hope to provide a better understanding of the terrestrial export of dissolved organic matter and its fate and impacts on coastal ecosystem functioning, i.e. the storage and cycling of carbon, nitrogen and phosphorous. A substantial amount of nutrients and carbon is leaving terrestrial environments as dissolved organic matter and transported to coastal areas where the bound nutrients are made available for the biota. Thus, neglecting this source of in DOM could lead to wrong management strategies. With an increased control of the export of inorganic nutrients at the European level, there is a growing need to understand the production, fate and effects of DOM in coastal ecosystems and to increase the knowledge both quantitatively and qualitatively, and ultimately find out how we can manage such effects (Räike et al. 2016).
The central aim of this work has been to investigate the seasonality of the optical, chemical and biological dynamics of dissolved organic matter (DOM) and inorganic nutrients in coastal regions and source waters. This has involved comparing the inputs from widely different catchment sources including peatlands, agricultural dominated catements as well as those covered by forests (Asmala et al. 2014; Hulatt et al. 2014).
As well as the input processes, we also measure loss processes we have also performed experiments to investigate the photochemical bleaching and decomposition of DOM as well as biological production and removal of DOM. With this information we are able to determine the importance of freshwater inputs on the optical and chemical properties of coastal waters and the photochemical and biological dynamics of the DOM pool. We shall be able to establish how these properties vary seasonally and the relative importance of allochthonous and autochthonous inputs to the sub-components of DOM as well as linking these with seasonal dynamics in inorganic nutrients (Räike et al. 2016).