Search results for "boreal lakes"

Increasing concentration of polyunsaturated fatty acids in browning boreal lakes is driven by nuisance algaGonyostomum

2020

Elevated concentrations of dissolved organic carbon (DOC) promote browning of lakes, which alters the physicochemical properties of water and ecosystem functioning. However, browning‐induced changes in basal production of polyunsaturated fatty acids from the n‐3 and n‐6 families (n‐3 and n‐6 PUFA) in lakes are not fully understood. The concentrations of PUFA, which are micronutrients required to maintain growth and reproduction of consumers, have been suggested to either rise or decline in seston as a response to lake browning. Elevated DOC concentrations may also promote bacterial biomass and production and thus potentially increase the concentration of bacterial fatty acids (BAFA) in sest…

Sunlit surface waters : exploring the photochemical reactivity of dissolved organic carbon

2017

In surface waters, solar radiation can photochemically mineralise the dissolved organic carbon (DOC, a measure of dissolved organic matter, DOM) to dissolved inorganic carbon (DIC). This DIC photoproduction constitutes an essential yet vague flux in the aquatic carbon cycling. The present thesis is based on the empirical assessment of the DOC photochemical reactivity, which was determined as the spectral apparent quantum yields (AQY) for DIC photoproduction. First, AQYs were determined in DOM solutions to quantify the impact of pH and DOM-associated iron. Then boreal lake waters were used for assessing the alteration of DOC photoreactivity due to water quality and catchment property. By sim…

Modelling phytoplankton in boreal lakes

2014

Regular build-up of the spring phytoplankton maximum before ice-break in a boreal lake

2016

The development of phytoplankton biomass and composition in a eutrophic boreal lake was studied during the evolution of under-ice convection in spring. The results from 8 yr showed that, within a few weeks before ice-break, phytoplankton biomass regularly increased by up to two or three orders of magnitude, reaching or exceeding the biomass in summer. Accordingly, this may be the most significant single annual phytoplankton episode in the lake. The development of phytoplankton was closely coupled with that of convection created by solar radiation at water temperatures < 4°C. In addition to vertical convection which keeps phytoplankton suspended, there was also horizontal convection which tr…