Determining the high variability of pCO2 and pO2 in the littoral zone of a subtropical coastal lake

Abstract

Abstract:The aquatic metabolism comprises production and mineralization of organic matter through biological processes, such as primary production and respiration that can be estimated by gases concentration in the water column. Aim: The study aimed to assess the temporal variability of pCO 2 and pO 2 in the littoral zone of a subtropical coastal lake. Our hypotheses are i) high variability in meteorological conditions, such as temperature and light, drive the high variability in pCO 2 and pO 2 , and ii) the lake is permanently heterotrophic due to the low phosphorus concentration. Methods: We estimated pCO 2 from pH-alkalinity method, and pO 2 from dissolved oxygen concentration and water temperature measured in free-water during 24 hours in the autumn, winter, spring and summer. Results: Our findings showed that limnological variables had low temporal variability, while the meteorological variables and pCO 2 presented a high coefficient of variation, which is representative of each climatic season. In autumn and winter, it was recorded that the lake was supersaturated in CO 2 relative to the atmosphere, while in spring and summer CO 2 concentration was below the concentration found in the atmosphere. Over 24 hours, pCO 2 also showed high variability, with autumn presenting higher concentration during the night when compared to daytime. Water temperature and chlorophyll a were negatively correlated with pCO 2 , while pO 2 was positively correlated with wind and light. Conclusion: Agreeing with our first hypothesis, pCO 2 showed an expressive temporal variation in a subtropical lake associated to the high variability in meteorological conditions. On the other hand, our second hypothesis was not confirmed, since Peri Lake exported CO 2 to the atmosphere in some periods and in others, CO 2 was removed from the atmosphere.Keywords: subtropical, temporal variation, aquatic metabolism, meteorological conditions, seasonality.Resumo: O metabolismo aquático envolve os processos de produção e mineralização da matéria orgânica através de processos biológicos, tais como produção primária e respiração, que podem ser estimados através da concentração de gases na coluna d'água. Objetivo: O objetivo do presente estudo foi determinar a variabilidade temporal da pCO 2 e da pO 2 na zona litorânea de uma lagoa costeira subtropical, tendo como hipótese que i) a alta variabilidade nas condições meteorológicas, tais como temperatura e luz, direcionam a elevada variabilidade na pCO 2 e pO 2 e que ii) o ambiente é permanentemente heterotrófico devido à baixa concentração de fósforo. Métodos: Nós estimamos a pCO 2 através do método pH-alcalinidade, e a pO 2 a partir da concentração de oxigênio dissolvido e temperatura da água, medidos em água livre, durante 24 horas, no outono, inverno, primavera e verão. Resultados: Nossos resultados mostraram que as variáveis limnológicas amostradas apresentaram baixa variabilidade temporal, porém as variáveis meteorológicas e a pCO 2 apresentaram elevado coeficiente de variação, refletindo a variação...

Symbiodinium mitigate the combined effects of hypoxia and acidification on a noncalcifying cnidarian

“…Cassiopea sp. inhabit shallow tropical and subtropical coastal waters and lagoons (Hofmann, Fitt, & Fleck, ) that exhibit considerable fluctuations of DO and pH (e.g., Gray, Degrandpre, Langdon, & Corredor, ; Tonetta, Fontes, & Petrucio, ). Cassiopea sp.…”

“…was KLEIN ET AL. (Hofmann, Fitt, & Fleck, 2003) that exhibit considerable fluctuations of DO and pH (e.g., Gray, Degrandpre, Langdon, & Corredor, 2012;Tonetta, Fontes, & Petrucio, 2014). Cassiopea sp.…”

Daily Variations in pCO2 and fCO2 in a Subtropical Urbanizing Lake

“…In general, surface-water pCO 2 is mainly controlled by four interrelated phenomena: thermodynamic effects, physical mixing, biological activities, and water-atmosphere CO 2 inter-exchange (Yang et al, 2019;Wang et al, 2021). Aquatic environmental variables, such as surface acidity (Pardue et al, 1988), trophic states (Tonetta et al, 2014), chlorophyll level (Xu et al, 2019;Yang et al, 2019), and water temperature (Marotta et al, 2009;Kosten et al, 2010), and other parameters, such as dissolved oxygen (DO), wind speed and solar radiation (Marce et al, 2015;Chen et al, 2017), are closely related to these four phenomena and might cause fluctuations in the spatial-temporal variability of pCO 2 and CO 2 evasion. Regarding inland freshwater systems, numerous studies have been conducted to investigate pCO 2 and CO 2 evasion in large rivers (with widths greater than 100 m), such as the Amazon (Richey et al, 2002;Abril et al, 2014), Mississippi (Crawford et al, 2016), Yangtze (Li et al, 2012;Liu et al, 2017) and Yellow Rivers (Ran et al, 2015).…”

“…Unlike the conditional conversion between the "source" and "sink" roles of marine ecosystems (Sabine et al, 2004;Yan et al, 2018), most inland lakes/reservoirs function as net "sources" of CO 2 because they are heterotrophic systems, similar to rivers (Cole et al, 1994;Richey et al, 2002;Gu et al, 2011), while some small productive lakes as carbon "sinks" (Maier et al, 2021 and related refs.). Currently, the temporal variability of CO 2 in lakes/streams is taken into account in many studies, which find similar relationships between photosynthesis and remineralization in response to variations in solar insolation (Alin and Johnson, 2007;Callbeck et al, 2010;Marotta et al, 2010;Tonetta et al, 2014). However, lots of the field data collected for CO 2 evasion estimation have low temporal resolution, such as weekly to quarterly, and therefore ignore the diurnal variation in pCO 2 and thus the CO 2 flux.…”

“…In addition, aquatic pCO 2 is markedly affected by photosynthesis (P) and respiration (R), which are driven by temperature and radiation in different geographic regions (Marotta et al, 2010;Tonetta et al, 2014;Xu et al, 2019). For example, the average CO 2 flux in the headwater catchment area of the Alaska Highlands, in Arctic tundra, is 5.1 μmol C m 2 s −1 (Crawford et al, 2013), while the average CO 2 emissions in the two reservoirs in Spain (Guadalcacín and Bornos), in the Mediterranean climate, are between 5.6 and 34.7 μmol C m 2 s −1 (Morales- Pineda et al, 2014).…”