Periphyton support for littoral secondary production in a highly humic boreal lake

Greening of the boreal peatland food web: Periphyton supports secondary production in northern peatlands

“…It is also noteworthy that some herbivores had lower δ 13 C than periphyton, which could reflect the inclusion of highly 13 C‐depleted heterotrophic bacteria (e.g., methane‐oxidizing bacteria) as another source of dietary carbon (van Duinen et al 2013). Similar findings have been reported from ecosystems where high DOC concentrations serve as the primary source of organic matter for heterotrophic bacteria, resulting in strongly depleted 13 C values that are transferred through the food web (Vesterinen et al 2016; Kendrick et al 2018).…”

“…Specifically, we found that periphyton contributed more to invertebrate diet over the growing season (71-76% in rich, 78-81% in moderate, and 20-65% in poor) compared to all other possible sources of carbon combined (e.g., bryophytes, vascular plants, or detritus), which contribute less than 17% in the poor fen and less than 9% in moderate and rich fens. These findings add to a growing body of literature challenging the notion that primary production by algae is of minor importance to peatland energy flow (van Duinen et al 2013;Mieczan et al 2015;Vesterinen et al 2016;DeColibus et al 2017). It is also noteworthy that some herbivores had lower δ 13 C than periphyton, which could reflect the inclusion of highly 13 C-depleted heterotrophic bacteria (e.g., methane-oxidizing bacteria) as another source of dietary carbon (van Duinen et al 2013).…”

“…For example, in ecosystems where detritus is the primary source of organic matter (i.e., a detrital‐based system; Wissinger et al 2018) animal diets can be supplemented by temporary increases in autotrophic production (i.e., green energy; Crenier et al 2017). These brief but intense inputs of high‐quality green organic matter (e.g., algal production) play a substantial role in sustaining secondary production (Mariash et al 2014; Vesterinen et al 2016; Vadeboncoeur and Power 2017), highlighting the importance of understanding the interactions within and between autotrophic and heterotrophic pathways in aquatic ecosystems.…”

Epiphytic bacteria make an important contribution to heterotrophic bacterial production in a humic boreal lake

“…Nutrient concentrations, in turn, remain rather constant in the hypolimnion through the stratification period (Vesterinen et al 2016a). As only a small part of the total epiphyton biomass in the littoral is grazed by littoral invertebrates during the summer (Vesterinen et al 2016b), the remaining biomass is presumably decomposed in the water column and may contribute to the relatively high hypolimnetic BP in the autumn.…”

Substratum‐Associated Microbiota

“…The above studies focused on the effects of pelagic production on benthic production, but benthic production may also stimulate pelagic production. Vesterinen et al (2016) found that chironomids and ephemeropterans may include methane-oxidizing bacteria in their diet in humic Lake Mekkojärvi (Finland), and that the presence of zooplanktivorous fish may increase benthic-pelagic coupling by forcing zooplankton into the littoral zone.…”