Coupling dissolved organic carbon, CO₂ and productivity in boreal lakes

Abstract

Summary Lakes worldwide are in rapid change because of direct or indirect climate impacts. In boreal areas, the increased concentrations of dissolved organic matter (DOM) are profoundly affecting light climate and productivity in multiple ways. Photochemical and microbial mineralisation of DOM are major sources of CO2 in these lakes. It has been suggested that this CO2 could potentially promote primary production and offset negative impacts of increased light attenuation. A synoptic survey of 76 Scandinavian lakes along gradients of DOM and total phosphorus (TP) revealed a major negative impact of DOM on primary production and algal biomass primarily related to light attenuation, whilst a strong positive impact of TP. The negative impact of DOM on lake productivity is thus partly offset by DOM‐associated P. Concentrations of CO2 did not relate significantly to either production, biomass, or seston stoichiometry, and thus whilst elevated CO2 may promote primary production in more productive lakes, it does not in these CO2‐supersaturated boreal lakes. Zooplankton biomass correlated strongly with TP and total algal biomass, less so with primary production, and was negatively related to DOM, likely reflecting the autotroph responses to DOM.

Interaction effects of zooplankton and CO2 on phytoplankton communities and the deep chlorophyll maximum

“…Overall, in our experimental food‐web context we did not observe positive responses to CO 2 in the phytoplankton as expected from laboratory studies or others carried out with simplified plankton communities; instead, we observed either neutral effects or declines in biomass that are more in line with results from a recent cross‐lake survey (Hessen et al., ). We hypothesise that complex food‐web interactions and nutrient limitation may explain these discrepancies from simple laboratory or food‐web experiments.…”

“…In support of our observations, in a cross‐lake study, Hessen et al. () observed no effect of CO 2 on phytoplankton biomass in CO 2 ‐saturated lakes similar to ours, also a result contrasting with laboratory studies. The lack of biomass increase we observed, despite an increase in primary productivity, could be explained by a decrease in cellular Chl‐ a content after acclimation to elevated CO 2 conditions (Sobrino, Neale, Phillips‐Kress, Moeller, & Porter, ; Sobrino, Ward, & Neale, ).…”

“…Indeed, several laboratory studies have demonstrated positive effects of CO 2 on photosynthetic plankton (ex. Jansson et al., ; Low‐Decarie, Fussmann, & Bell, ; Kim et al., ; Tortell et al., ; Urabe et al., ), although field studies are more equivocal (Hessen, Håll, Thrane, & Andersen, ).…”

Evaluations of Climate and Land Management Effects on Lake Carbon Cycling Need to Account for Temporal Variability in CO2 Concentrations

“…These references contributed to the supporting files: Aalto et al (2014), Abnizova et al (2012), Aroian (1947), Ask et al (2012), Bartoń (2015), Bartosiewicz et al (2015), Bennett et al (1999) Domysheva et al (2013Domysheva et al ( , 2010, Dunalska et al (2004), Fee et al (1996), Filzmoser and Gschwandtner (2011), Findlay et al (1999), Finlay et al (2009, Fontes et al (2015), Fraterrigo andDowning (2008), Freeman et al (2001), Fukushima et al (1996), Garcia et al (2007), Gelbrecht et al (1998), Goodman et al (2011), Gu et al (2011), Haberyan et al (2003, Hamilton et al (1994Hamilton et al ( , 1995, Heiskanen et al (2015), Hessen et al (1997Hessen et al ( , 2017, Hesslein et al (1991, 2009), Högberg et al (2001, Holgerson (2015), Hope et al (1996), Hruška et al (2003), Huttunen et al (2002), Jenson (1991), Jeppesen et al (2016), Jones and Mulholland (1998), Jones et al (2001, 2009, Kankaala et al (2013),…”

Heterocope borealis in Norway - A copepod on the move, or on the edge of its natural distribution?

“…found it in Lake Raslången which is farther south, on the border between Skåne and Blekinge counties. In a recent study of 75 lakes located between latitude 57-64°N from the Norwegian west coast to the Swedish east coast (Hessen et al 2017), H. borealis was not recorded in pelagic samples from any of the 31 Swedish lakes investigated (Walseng unpubl.). Other available literature does not state finds of the species in central Sweden either.…”