Year-round measures of planktonic metabolism reveal net autotrophy in surface waters of a Great Lakes estuary

Defore, Angela L.; Weinke, Anthony D.; Lindback, Morgan; Biddanda, Bopaiah A.

doi:10.3354/ame01790

Cited by 9 publications

(2 citation statements)

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“…P:R ratios < 1 have frequently been interpreted as evidence of consumer reliance on allochthonous organic carbon (Thorp and Delong 2002). Central to the foundational understanding of the relationship between net heterotrophy (R > P) and terrestrial support of aquatic food webs are the ideas that in persistently net autotrophic ecosystems (where P:R > 1), food webs are based on phytoplankton OC (e.g., Defore et al 2016), while in persistently heterotrophic ecosystems (where P:R < 1) terrestrial OC is actively incorporated into the food web (e.g., Urabe et al 2005). We review evidence that mid‐lake P:R ratios, despite their appealing simplicity, offer limited insights into metazoan reliance on allochthonous OC owing to (1) the strong effect of microbial production efficiency on R; (2) the strong reliance of metazoan production on autochthonous production irrespective of the rate and amount of allochthonous OC supplied; and (3) the differential effects of external OC supplied in dissolved forms in the water column relative to particulate forms to the benthos.…”

Section: Introductionmentioning

confidence: 99%

Shoring up the foundations of production to respiration ratios in lakes

Vadeboncoeur

2021

Limnology & Oceanography

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The ratio of primary production to ecosystem respiration rates (P:R ratio) is an ostensibly simple calculation that is used to characterize lake function, including trophic status, the incorporation of terrestrial organic carbon into lacustrian food webs, and the direction of carbon dioxide (CO 2 ) flux between a lake and the atmosphere. However, many predictive links between P:R ratios and lake ecosystem function stem from a historically plankton-centric perspective and the common use of the diel oxygen curve approach. We review the evolution of the use of P:R ratios and examine common assumptions underlying their application to (1) eutrophication, (2) carbon flux through lake food webs, and (3) the role of lakes in the global carbon budget. Foundational P:R studies have been complicated principally by the following: most P:R ratios were calculated from mid-lake measurements and failed to incorporate nonplanktonic dynamics; there has been confusion regarding the food web implications when P:R ≠ 1; and CO 2 fluxes between lakes and the atmosphere are influenced by nonmetabolic processes. We argue for a re-assessment, or shoring up, of several fundamental assumptions that continue to guide metabolism research in lakes by accounting for mixing, benthic-littoral processes, groundwater fluxes, and abiotic controls on gas dynamics to better understand lake food webs and accurately integrate lake ecosystems into landscape-scale carbon cycling models.

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Section: Introductionmentioning

confidence: 99%

Shoring up the foundations of production to respiration ratios in lakes

Vadeboncoeur

2021

Limnology & Oceanography

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“…At the daily scale, light and temperature are a primary control on GPP (Langman et al 2010;Richardson et al 2017), yet on the weekly scale storms events can be an important driver of GPP (Jennings et al 2012). Seasonal changes to metabolism are largely driven by temperature and light (Hansen et al 2006;Langman et al 2010;Yvon-Durocher et al 2010;Defore et al 2016). In a detailed study of metabolism of a Danish lake, daily GPP values were strongly related to temperature, but GPP was seasonally dependent on temperature coupled with irradiance and primary producer biomass (Staehr and Sand-Jensen 2007).…”

Section: Discussionmentioning

confidence: 99%