Hydrodynamic Control of Plankton Spatial and Temporal Heterogeneity in Subtropical Shallow Lakes

Cardoso, Luciana de Souza; Fragoso, Carlos Ruberto; Souza, Rafael Siqueira; Marques, David da Motta

doi:10.5772/30669

Cited by 8 publications

(12 citation statements)

References 51 publications

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“…However, apart from the marginally higher CO 2 accumulation in November 2010 in the pelagic zone, the extensive sampling of 2010–2011 did not show such striking evidence in support of the hypothesis. This could be due to the smaller number of points sampled, but also the result of intensive mixing of Lake Mangueira by wind (Cardoso et al, 2012), which makes it difficult to detect abrupt differences in respiration in the field, as indicated by several marginal relationships found. This could have been crucial because of the smaller set of sampling points.…”

Section: Discussionmentioning

confidence: 99%

Lower Respiration in the Littoral Zone of a Subtropical Shallow Lake

2013

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Macrophytes are important sources of dissolved organic carbon (DOC) to littoral zones of lakes, but this DOC is believed to be mostly refractory to bacteria, leading to the hypothesis that bacterial metabolism is different in littoral and pelagic zones of a large subtropical shallow lake. We tested this hypothesis by three approaches: (I) dissolved inorganic carbon (DIC) accumulation in littoral and pelagic water; (II) O2 consumption estimate for a cloud of points (n = 47) covering the entire lake; (III) measurement of O2 consumption and CO2 accumulation in dark bottles, pCO2 in the water, lake-atmosphere fluxes of CO2 (fCO2) and a large set of limnological variables at 19 sampling points (littoral and pelagic zones) during seven extensive campaigns. For the first two approaches, DIC and O2 consumption were consistently lower in the littoral zone, and O2 consumption increased marginally with the distance to the nearest shore. For the third approach, we found in the littoral zone consistently lower DOC, total phosphorus (TP), and chlorophyll a, and a higher proportion of low-molecular-weight substances. Regression trees confirmed that high respiration (O2 consumption and CO2 production) was associated to lower concentration of low-molecular-weight substances, while pCO2 was associated to DOC and TP, confirming that CO2 supersaturation occurs in an attempt to balance phosphorus deficiency of macrophyte substrates. Littoral zone fCO2 showed a tendency to be a CO2 sink, whereas the pelagic zone showed a tendency to act as CO2 source to the atmosphere. The high proportion of low-molecular-weight, unreactive substances, together with lower DOC and TP may impose lower rates of respiration in littoral zones. This effect of perennial stands of macrophytes may therefore have important, but not yet quantified implications for the global carbon metabolism of these lakes, but other issues still need to be carefully addressed before rejecting the general belief that macrophytes are always beneficial to bacteria.

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Section: Discussionmentioning

confidence: 99%

Lower Respiration in the Littoral Zone of a Subtropical Shallow Lake

2013

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“…The abiotic variables used in the RDAs (see Table 1) were previously selected after an exploratory analysis (Pricipal Component Analysis, PCA) given in Freitas-Teixeira et al 2016, based on the same data set, being the higly correlated variables (r>0.8) excluded. Climatic variables were included in the abiotic matrix considering their importance to the ecosystem dynamics, as showed by previous studies (Cardoso et al, 2012;Fragoso Junior et al, 2008). The RDA biplot were built indicating the variables with higher correlations with the canonic axes.…”

Section: Data Analysesmentioning

confidence: 99%

Responses of the phytoplankton functional structure to the spatial and temporal heterogeneity in a large subtropical shallow lake

et al. 2018

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Aim Studies on biological communities that take into account only the species composition and abundances (or biomass) and their relative contributions, most of the time, do not reflect their ecological functions, especially considering the wide spatial and temporal variation of large shallow lakes. This paper aimed at evaluating the influence of environmental spatial and temporal heterogeneity on the functional structure of phytoplankton in a subtropical large shallow lake. Methods Seasonal samplings were carried out in 2010 and 2011, in 19 sampling sites distributed along the entire length (90 km) and width (3-10 km) of Lake Mangueira, a large (820 km2 ) and shallow lake (zmean = 2.6 m), comprising the littoral and pelagic zones of the north, central and southern regions. Abiotic variables and phytoplankton functional traits (volume, maximum linear dimension, life forms) and functional groups were analyzed as measures of functional structure. Results The results showed that there was no spatial organization of phytoplankton functional traits during the study. Colonial non-flagellated organisms, organisms with cellular volume between 103 and 104 μm3 and greater than 104 μm3, and with maximum linear dimension between 21 and 50 μm prevailed in all zones and regions. Phytoplankton functional groups and traits responded to resource variation, especially increasing their variety and contribution during spring and summer periods. Conclusions The functional structure of the phytoplankton community in Lake Mangueira, here accessed by functional traits and RFGs, was more conditioned by its environmental temporal variability rather than by the spatial variation, indicating that the resources and life conditions seasonal variation strongly influence the phytoplankton in this ecosystem.

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“…north to south, as has been observed or taken into account in other studies (CROSSETTI et al, 2013;FRAGOSO JUNIOR et al, 2011;RODRIGUES, 2009). External forcing factors, such as the wind (both speed and direction) also can affect the temporal and spatial distribution of phytoplankton in large shallow lakes (CARDOSO et al, 2012;CARRICK;ALDRIDGE;SCHELSKE, 1993;KONG;FAO, 2005;WEBSTER;HUTCHINSON, 1994). In these environments, wind conditions impose stress on the system, in which the biological responses (e.g., Chl-a) can be interconnected, in contrast to environments such as temperate lakes and oceans.…”

Section: Performance Of Chl-a Algorithmsmentioning

confidence: 99%

“…Limitations of Chl-a detection by remote sensing include atmospheric correction methods and sensor limitations, as well as the influences of detritus, the presence of colored dissolved organic matter (CDOM), and scattering by Total Suspended Matter (TSM), which are difficult to detect because they affect the optical properties of water (DARECKI;STRAMSKI, 2004;HU, 2009;WU et al, 2009). Another limitation is the light reflected off the bottom, which may affect the accuracy of the empirical algorithm because the signal received by the sensor varies as a function of the wavelength and with the clarity of the water (CARDOSO et al, 2012;SHUBHA, 2000;LEE et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

“…We used multiple linear regression, artificial neural network, nonparametric multiplicative regression, and four models (Appel, Kahru,FAI and O14a) to retrieve the Chl-a concentration in the Lake Mangueira, a large shallow subtropical lake located in Southern Brazil. This approach is the first attempt to assess the application of remote sensing techniques in such a system, which the oligotrophic conditions are common most of the time (CROSSETTI et al, 2013;LIMA et al, 2016), and the spatial heterogeneity has large differences between the littoral and pelagic zones (CARDOSO et al, 2012;CROSSETTI et al, 2013;THEY;SOUZA, 2012).…”

Section: Introductionmentioning

confidence: 99%

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Can chlorophyll-a in meso-oligotrophic shallow waters be estimated using statistical approaches and empirical models from MODIS imagery?

Munar

Cavalcanti

Bravo

et al. 2018

RBRH

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Accurate estimation of chlorophyll-a (Chl-a) concentration in inland waters through remote-sensing techniques is complicated by local differences in the optical properties of water. In this study, we applied multiple linear regression (MLR), artificial neural network (ANN), nonparametric multiplicative regression (NPMR) and four models (Appel, Kahru, FAI and O14a) to estimate the Chl -a concentration from combinations of spectral bands from the MODIS sensor. The MLR, NPMR and ANN models were calibrated and validated using in-situ Chl -a measurements. The results showed that a simple and efficient model, developed and validated through multiple linear regression analysis, offered advantages (i.e., better performance and fewer input variables) in comparison with ANN, NPMR and four models (Appel, Kahru, FAI and O14a). In addition, we observed that in a large shallow subtropical lake, where the wind and hydrodynamics are essential factors in the spatial heterogeneity (Chl-a distribution), the MLR model adjusted using the specific point dataset, performed better than using the total dataset, which suggest that would not be appropriate to generalize a single model to estimate Chl-a in these large shallow lakes from total datasets. Our approach is a useful tool to estimate Chl -a concentration in meso-oligotrophic shallow waters and corroborates the spatial heterogeneity in these ecosystems.Keywords: Chl-a; MLR; ANN; NPRM; Remote sensing; Lake Mangueira. RESUMOA estimativa da concentração de Clorofila-a (Chl-a) em ambientes aquáticos através de técnicas de sensoriamento remoto é complexa devido as diferenças entre as propriedades óticas da água. O objetivo deste trabalho foi estimar concentrações de Chl-a a partir das combinações de bandas espectrais do sensor MODIS, aplicando análise de regressão linear múltipla (MLR), redes neurais artificiais (ANN), regressão multiplicativa não paramétrica e quatro modelos (Appel, Kahru, FAI e O14a). Os modelos de regressão linear múltipla (MLR), NPMR e ANN foram calibrados e validados utilizando medições in-situ de Clorofila-a. Os resultados demostraram que um simples e eficiente modelo desenvolvido e validado através de regressão linear múltipla (MLR) produz vantagens (i.e., melhor performance e poucas variáveis de entrada) em comparação com os modelos ANN, NPMR e quatro modelos (Appel, Kahru, FAI e O14a). Além disso, foi observado que em um grande lago raso subtropical, no qual o vento (intensidade e direção) e a hidrodinâmica são fatores essenciais na heterogeneidade espacial (distribuição de Chl-a), o modelo MLR desenvolvido utilizando um ponto específico do lago teve melhor performance que utilizando o total de dados, sugerindo que não seria apropriado generalizar um único modelo para estimar Clorofila-a nesses grandes lagos rasos utilizando o total de dados. Esta abordagem é uma ferramenta útil para estimar concentrações de Chl-a em ambientes rasos meso -oligotróficos e corroborar a heterogeneidade espacial desses ecossistemas. Can chlorophyll-a in meso-oligotrophic s...

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Hydrodynamic Control of Plankton Spatial and Temporal Heterogeneity in Subtropical Shallow Lakes

Cited by 8 publications

References 51 publications

Lower Respiration in the Littoral Zone of a Subtropical Shallow Lake

Lower Respiration in the Littoral Zone of a Subtropical Shallow Lake

Responses of the phytoplankton functional structure to the spatial and temporal heterogeneity in a large subtropical shallow lake

Can chlorophyll-a in meso-oligotrophic shallow waters be estimated using statistical approaches and empirical models from MODIS imagery?

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