Mixing patterns in Amazon lakes

Tundisi, J. G.; Forsberg, Bruce R.; Devol, Allan H.; Zaret, Thomas M.; Tundisi, Takako Matsumura; Santos, Antonio; Ribeiro, Jorge S.; Hardy, Elsa Rodrigues

doi:10.1007/bf02391627

Cited by 34 publications

(8 citation statements)

References 23 publications

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“…Thirteen shrimps (Euryrhynchus amazoniensis) carrying eggs were noted from 1.5-4 m depth, three of them from 4 m. This is in marked contrast to results from other areas of amazonian inundation forests, where oxygen depletion impoverishes the benthos at greater depth. Tundisi et al (1984) report 02 levels of 0.5-1.5 mg l-I from 5 m depth to surface water for the V~zea lake Jacaretinga, and Irmler (1975) measured 1.8 mg 1-1 near the bottom of the 'ria-lake' of the Tarum~-Mirfm, in ca 8 m depth. In June 1990, during INPA's aquatic ecology course, we confirmed Irmler's measurements.…”

Section: Results and Commentsmentioning

confidence: 99%

The benthic litter-dwelling macrofauna of the Amazonian forest stream Tarumã-Mirím: patterns of colonization and their implications for community stability

Walker

1994

Hydrobiologia

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Between 1983 and 1988 a total of 928 litter-filled baskets (1.8 1 volume), exposed for various periods on a stream litterbank and in its vicinity, collected 2703 individuals of 122 macrofaunal species, excluding chironomids. Species abundance was analysed in relation to exposure time, annual inundation cycle, water depth and sample size. Long-term, average species packing and animal density proved to be relatively invariant and revealed non-random frequency patterns. Previous and present data indicate that these patterns are a function of regular, specific life cycles and of intra-specific, stereotype behaviour in relation to space and litter quality, among other possibilities not considered here. Potential competition for space in these communities is discussed, considering the assumption of individual random movement versus species maintenance as a function of genetically and neurophysiologically informed, non-random behaviour.

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Section: Results and Commentsmentioning

confidence: 99%

The benthic litter-dwelling macrofauna of the Amazonian forest stream Tarumã-Mirím: patterns of colonization and their implications for community stability

Walker

1994

Hydrobiologia

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“…In the 48 h preceding this sampling, there was a drop in average of air temperature, from 28 to 23.5 °C . This rapid but infrequent drop in temperature, locally called a “friagem” event, is known to promote the rapid destratification and vertical mixing of floodplains waters, resulting in the introduction of anoxic hypolimnetic waters rich in H 2 S, NH 4 , CH 4 , and MeHg to the surface. − The exceptionally low concentration of dissolved oxygen and high concentration of MeHg observed in the Jutaí River at this time suggests that these anoxic floodplain waters were rapidly transported to the river channel. The exceptionally high concentration of dissolved methane encountered in the Jutaí River at the time of our sampling support the “friagem” hypothesis …”

Section: Discussionmentioning

confidence: 99%

Methylmercury Modulation in Amazon Rivers Linked to Basin Characteristics and Seasonal Flood-Pulse

Kasper

Forsberg

Amaral

et al. 2017

Environ. Sci. Technol.

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We investigated the impact of the seasonal inundation of wetlands on methylmercury (MeHg) concentration dynamics in the Amazon river system. We sampled 38 sites along the Solimões/Amazon and Negro rivers and their tributaries during distinct phases of the annual flood-pulse. MeHg dynamics in both basins was contrasted to provide insight into the factors controlling export of MeHg to the Amazon system. The export of MeHg by rivers was substantially higher during high-water in both basins since elevated MeHg concentrations and discharge occurred during this time. MeHg concentration was positively correlated to %flooded area upstream of the sampling site in the Solimões/Amazon Basin with the best correlation obtained using 100 km buffers instead of whole basin areas. The lower correlations obtained with the whole basin apparently reflected variable losses of MeHg exported from upstream wetlands due to demethylation, absorption, deposition, and degradation before reaching the sampling site. A similar correlation between %flooded area and MeHg concentrations was not observed in the Negro Basin probably due to the variable export of MeHg from poorly drained soils that are abundant in this basin but not consistently flooded.

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“…The low DO concentration found during the high-water period is related to the flooding of large lateral areas and the increased surface area of aquatic vegetation subjected to sedimentation, decomposition and planktonic respiration which reduces DO (Devol, Forsberg, Richey, & Pimentel, 1995). Also, daily stratification is commonly observed in the Amazon region due to slight and temporary changes in water temperature and density (Lewis, 1987;Sarmento, 2012;Tundisi et al, 1984) that could contribute to these low DO concentrations. Chlorobi increased although cyanobacteria are important community members in Lake Janauacá all year round.…”

Section: Seasonal Variations In Environmental Conditions and Bccmentioning

confidence: 99%

Flood pulse regulation of bacterioplankton community composition in an Amazonian floodplain lake

et al. 2018

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Understanding spatial and temporal dynamics of microbial communities is a central challenge in microbial ecology since microorganisms play a key role in ecosystem functioning and biogeochemical cycles. Amazonian aquatic systems comprise a dynamic mosaic of heterogeneous habits but are understudied and there is limited information about the mechanisms that shape bacterial community composition (BCC). There is a consensus that environmental selection (species sorting) and dispersal processes (source–sink dynamics) act in concert to shape the composition of these communities, but the relative importance of each mechanism may vary dramatically through time and between systems. Applying 16S rRNA gene amplicon high‐throughput sequencing, we studied factors and processes that modulate BCC in an Amazonian floodplain lake and used source‐tracking models to trace the main dispersal sources of microorganisms in the whole floodplain system during a full hydrological cycle. Our source‐tracking models indicated that dispersal processes were predominant, explaining most of the BCC variability throughout the study period. We observed more sources contributing to the sink community during the falling water than rising water period, when contributions from the Solimões River dominated. There was a clear seasonal pattern in BCC, closely related to environmental variables, suggesting that the successful establishment of dispersing bacteria also depends on environmental filtering that is linked to water flow. In summary, source–sink dynamics and species sorting were strongly affected by water exchange and connectivity with the main river that varied throughout the flood pulse cycle. Our results demonstrated the influence of lateral transport and temporal dynamics on BCC in Amazonian floodplain lakes that could ultimately impact regional carbon budgets and biogeochemical cycles.

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Mixing patterns in Amazon lakes

Cited by 34 publications

References 23 publications

The benthic litter-dwelling macrofauna of the Amazonian forest stream Tarumã-Mirím: patterns of colonization and their implications for community stability

The benthic litter-dwelling macrofauna of the Amazonian forest stream Tarumã-Mirím: patterns of colonization and their implications for community stability

Methylmercury Modulation in Amazon Rivers Linked to Basin Characteristics and Seasonal Flood-Pulse

Flood pulse regulation of bacterioplankton community composition in an Amazonian floodplain lake

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