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1.
Autotrophic carbon sources for heterotrophic bacterioplankton in a floodplain lake of central Amazon 总被引:2,自引:1,他引:1
Andrea Viviana Waichman 《Hydrobiologia》1996,341(1):27-36
The relative contribution of autotrophic carbon sources (aquatic macrophytes, flooded forest, phytoplankton) for heterotrophic bacterioplankton was evaluated in a floodplain lake of the Central Amazon. Stable carbon isotopes (13C) were used as tracers. Values of 13C of different autotrophic sources were compared to those of dissolved organic carbon (DOC) and those of bacterially produced CO2.The percentage of carbon derived from C4 macrophytes for bacterially produced CO2 was the highest, on average 89%. The average 13C value of CO2 from bacterial respiration was –18.5 ± 3.3. Considering a fractionation of CO2 of 3 by bacterial respiration, 13C value was –15.5, near C4 macrophyte 13C value (–13.1).The average value of total DOC 13C was –26.8 ± 2.4. The percentage of C4 macrophytes carbon for total DOC was on average 17%. Considering that bacteria consume mainly carbon from macrophytes, the dominance of C3 plants for total DOC probably reflects a faster consumption of the former source, rather than a major contribution of the latter source.Heterotrophic bacterioplankton in the floodplain may be an important link in the aquatic food web, transferring the carbon from C4 macrophytes to the consumers. 相似文献
2.
Pronounced seasonal and daily oxygen concentration changes are characteristic for Amazonian floodplain lakes. Studies on the fish fauna of the Lago Camaleão, Solimões River, Amazonas, Brazil, showed several fish species which are able to survive prolonged periods of heavy hypoxia. Twenty species belonging to eight families were observed in the laboratory in order to determine their respiratory adaptations to hypoxic conditions and oxygen concentrations at which the fish present respiratory adaptations. Finally, the fish species were distributed throughout the habitats of Lake Camaleão according to their adaptation responses. Ten fish species used the surface water for aquatic surface respiration, four species used atmospheric oxygen for aerial respiration, four species used oxygen supplied by the exudation of the roots of floating macrophytes and two exhibited a high tolerance to hypoxic conditions, and well-developed physiological biochemical mechanisms. The fish fauna is well adapted to low oxygen concentrations. The large variety of morpho-anatomical adaptations associated with biochemical and physiological mechanisms to tolerate hypoxic and anoxic conditions enable the 20 fish species to exploit several habitats of Lago Camaleão, such as floating aquatic macrophyte meadows, open water and near the shoreline. 相似文献
3.
Matthias Koschorreck 《Biogeochemistry》2000,50(2):195-206
In the Amazon floodplain large areas of unvegetatedlake sediments are exposed to air during low water. Imeasured methane fluxes from exposed sediments of anAmazonian floodplain lake and assessed the regulatingfactors. Methane emission decreased from values between 10 and 40 mol CH4 mminus 2 hminus 1to zero when the sediments were exposed to air. Meanfluxes were about 3.7 mol CH4mminus 2 hminus 1. Fluxes were low compared tomeasurements taken from flooded habitats makingexposed lake sediments a negligible source ofatmospheric CH4. This was mainly due to the lackof ebullition which governs methane flux in theflooded phase. Methane oxidation at the sedimentsurface consumed up to 75% of the methane enteringthe oxidised zone. Compared with CO2 emissionmethane turnover was of minor importance for thecarbon budget of the sediments. 相似文献
4.
The composition of the phytoplankton of Lago Batata,a flood-plain lake connected to Rio Trombetas,undergoes a conspicuous annual cycle which is relatedto the hydrology (depth of water, rate of fluvialflushing) and the hydrography (stability, frequency ofmixing of the water) of the lake. From a sparsenanoplankton at high-water and high flushing, the lakepasses to desmid-diatom dominance and finally tofilamentous cyanobacteria when the lake is barely 2 mdeep. As it refills, the lake again becomes desmid-dominated; then, when the turbidity is least and thestratification most stable, Botryococcus becomesa major component. Eventually flushing becomes toorapid for any but the relatively fastest-growingspecies. These changes are gradual and, at the scaleof algal generation times, cannot be explained assharp or sudden disturbances. Neither do they have theproperties of ecological successions but ratherrepresent compositional responses to a progressiveenvironmental modification analogous to the floristicphenomenon of gradual climate change. 相似文献
5.
Nágila Zuchi Cristhiana Röpke Akemi Shibuya Thatyla Farago Marina Carmona Jansen Zuanon Sidineia Amadio 《Zeitschrift fur angewandte Ichthyologie》2020,36(6):837-841
Length-weight relationship (LWR) for 39 freshwater fish species captured in the Catalão Lake, a floodplain area at the confluence of the Amazonas and Negro rivers is presented. LWRs were calculated based on fish sampled over 18 years (1999–2017) using a set of ten gill nets with different mesh sizes, monthly immersed in water for 24-hr with 6-hr interval catches. Measurements were done for standard length (SL – 0.1 cm precision) and total weight (TW – 0.01 g precision). The LWRs were calculated by the linear regression of natural log-transformed SL and TW data: TW = a × SLb. All statistical analyses were performed with R software. From all species considered, 32 are new LWR records for the international literature as well as for the Amazonian ichythyofauna; additional records expand the known size range for seven species. 相似文献
6.
Factors affecting growth rates of young tropical floodplain fishes: seasonality and density-dependence 总被引:5,自引:0,他引:5
Peter B. Bayley 《Environmental Biology of Fishes》1988,21(2):127-142
Synopsis Deviations of growth increments from a model describing average growth of 12 common fish species, mostly juveniles, were compared
with hydrological variables and biomass density (ranging from 1 gm-2 to 83 gm-2 of potentially competing species of similar size ranges (guilds). Seasonal effects on growth were highly significant for
omnivores but not for detritivores. Omnivores exhibited faster growth during the rising water season, and higher growth rates
were associated with periods of increased rates of flooding during this season, which could be associated with increased availability
of food. No species exhibited density-dependent growth when all seasons were considered together. During the rising-water-level
season, no inverse relationship between growth and biomass density was found in any of the 11 species tested at p = 0.05.
During the short falling-water season, 2 of 8 species tested did exhibit density-dependent growth but a sign test of correlation
coefficients from all species was not significant. These two significant results were from four omnivores tested. However,
density-dependent growth was not indicated when the data were pooled within either detritivore or omnivore guilds by hydrological
season. It was concluded that with the possible exception of juvenile omnivores during the limited falling-water season, density-dependent
growth, and by implication interspecific competition, had no effect in regulating the species' populations investigated in
the floodplain environment. Conversely, the importance of a seasonal hydrological regime in maintaining growth rates, at least
for omnivores, was evident. 相似文献
7.
The distributions of the fish species were examined in relation to environmental variables, to evaluate the effects of environmental degradation on the fish community of Batata Lake, a typical Amazonian clearwater lake. From 1979 to 1989, tailings composed of water and clay, extracted from bauxite by water jets, were discharged into Batata Lake. The tailings spread into about 30% of the lake’s area, where the level of the lake bottom rose and turbidity increased. In the present study, multivariate analyses were performed on data for environmental parameters and fish density and biomass. Fish were collected with gillnets during the annual hydrological cycle (filling, flood, drawdown and dry periods), in the silted area, the partly silted area (intermediate) and the natural area. Values of the Shannon index, density and biomass were compared among areas and periods to evaluate the effects of the tailings on community structure. Sediment resuspension, which reduces transparency, is accentuated in shallow water, and was the main factor regulating differences in the community structure between the natural and silted areas. The decrease in transparency occurs mainly during the filling period in the silted area and during the low-water period in the silted and intermediate areas, when sediment resuspension increases concentrations of nutrients and chlorophyll-a. The strong influence of migratory and piscivore species in low-transparency waters is likely associated with the greater bacterioplankton productivity and turnover rate observed by other authors in the silted area, increasing the importance of the heterotrophic food chain in Batata Lake. Reduction of transparency in the silted area was a selective factor for fish species. The death of part of the flooded forest vegetation was decisive in lowering densities of the igapó-associated species in the silted area. The unconsolidated substrate, the death of part of the igapó forest and the negative effects of low transparency – inhibiting resident visually oriented species in the affected areas – are the main factors causing the low diversity in the silted area as a whole. The correlations between CPUEs, conductivity and nutrients and chlorophyll-a concentrations do not appear to reflect cause–effect relationships, indicating that these environmental parameters are poor predictors of fish density in Batata Lake. 相似文献
8.
9.
Influence of predation by fish and water turbidity on a Daphnia gessneri population in an Amazonian floodplain lake,Brazil 总被引:3,自引:3,他引:0
Mirian Leal Carvalho 《Hydrobiologia》1984,113(1):243-247
The population behavior of Daphnia gessneri Herbst, 1967 in a floodplain lake (Lago Grande) of the lower Rio Solimões was investigated between April 1979 and March 1980 with regard to 1) predation by the fish called tambaqui (Colossoma macropomum, Characidae), 2) water level fluctuation and 3) water transparency. Zooplankton density samples were collected at two sites near mid-lake, where water depth and Secchi disc transparency were measured. In addition, qualitative samples of zooplankton and fish collections were taken at several sites in the adjacent floodplain areas. The author concludes that fluctuations in Daphnia gessneri populations correlate most with intense predation by fish and water turbidity. 相似文献
10.
Morphological correlates of diet were examined in 48 species of freshwater fishes from floodplain lakes in the central part of the Mamoré River (Bolivian Amazon). The species were classified, according to the percentage occurrence of seven food items, into eight broad trophic categories: mud feeders, algivores, herbivores, terrestrial invertivores and omnivores, carnivores, zooplanktivores, aquatic invertivores and piscivores. There were significant relationships between the diet and morphology of the fishes even when the effect of taxonomical relatedness between species was eliminated. Relative gut length was the main morphological variable used to order species on a carnivore to mud feeder gradient. Standard length and head and mouth size were the morphological variables most closely associated with prey size. Mud feeder, algivore and piscivore species appeared as the most dietary and morphologically specialized. These results support both the hypotheses that species morphology influences the diet and that morphological similarity is conserved even in comparison with taxonomically unrelated species. 相似文献
11.
九龙江西溪漳州段浮游植物组成与环境因子的关系 总被引:1,自引:0,他引:1
分别在2010年的丰、平、枯3个时期,从浮游植物种类组成、生物量(叶绿素a含量)及其粒级结构等指标对九龙江漳州段浮游植物组成进行了调查,同时分析了其与环境因子间的关系,评估了该河段的水质质量。结果表明:研究区域微微型浮游植物占总生物量比例与温度存在显著的正相关性(P<0.05),小型浮游植物占总生物量比例与总氮成显著的负相关(P<0.05)。共鉴定出浮游植物7门59种,且在各时期均有差异;丰水期与枯水期相比,蓝藻比例上升(P<0.05),甲藻比例下降(P<0.05);研究水域Shannon-Wiener指数在1.0~3.0,为中度污染。典型对应分析表明,温度和营养盐是影响九龙江西溪漳州段浮游植物群落变化的主要环境因子。 相似文献
12.
13.
Evlyn Márcia Leão de Moraes Novo Cláudio Clemente de Farias Barbosa Ramon Moraes de Freitas Yosio Edimir Shimabukuro John M. Melack Waterloo Pereira Filho 《Limnology》2006,7(3):153-161
To assess seasonal changes in phytoplanktonic chlorophyll distributions in Amazon floodplain lakes, a linear mixing model
was applied to Moderate Resolution Imaging Spectroradiometer (MODIS) reflectance data acquired at four river stages: rising
(April), high (June), decreasing (September), and low (November). The study area is located in a floodplain reach from Parintins
(Amazonas) to near Almeirim (Pará). A three-end-member mixing model designed to uncouple three fractions [high suspended inorganic
matter (ip), low inorganic suspended matter (w), and high chlorophyll a (Chl)] was tested in Lake Curuaí (1.5°S 55.43°W) based on field sampling done almost concurrently with satellite overpasses.
During high water, phytoplankton patches are confined to lakes closer to terra firme under the influence of clear water inflow,
whereas during the low and decreasing water stages, the patches are more evenly distributed over the floodplain. 相似文献
14.
Susana Jose de Paggi 《Hydrobiologia》1995,310(2):87-94
The vertical distribution of zooplankton rotifers in the open waters of Laguna El Tigre was investigated. Rotifers showed a relatively uniform distribution throughout the water column. This pattern of distribution was maintained during the year and did not show variations in relation to hydrologic phases of inundation and isolation of the lake. Diel vertical migration of rotifers from the limnetic and the littoral area was investigated too. In littoral area rotifers exhibited a reverse migration, whereas in the limnetic the movements were less conspicuous. Horizontal migration was observed too, and there were interactions between horizontal and vertical distribution. Predation and competition offer a possible explanation. 相似文献
15.
Modelling the effects of changing retention time on abundance and composition of phytoplankton species in a small lake 总被引:2,自引:1,他引:2
1. The phytoplankton community model, PROTECH, was used to model the algal response to changing annual mean retention time in a small lake. 2. Simulations of short retention time with a fixed nutrient load resulted in a reduced chlorophyll concentration. A similar relationship was observed when the simulations were repeated but with inflowing nutrients increased in proportion to river discharge. 3. Longer retention time caused the spring bloom to start earlier and the autumn bloom to persist longer. 4. Changes in discharge of the inflowing river also caused a change in the thermal structure of the lake. This change in thermal structure, in turn, influenced the magnitude and composition of the phytoplankton population, particularly those in the CS‐functional group, such as Aphanizomenon. 相似文献
16.
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17.
Species composition and phytoplankton biomass in a tropical African lake (Lake Awassa,Ethiopia) 总被引:2,自引:2,他引:0
The species composition and phytoplankton biomass of Lake Awassa, Ethiopia were studied from September 1985 to July 1986 in relation to some limnological features of the lake. During the study period, three phases of thermal stratification were recognized: a period of unstable stratification and near-complete mixing was followed by a stable stratification period and another period of complete mixing. Complete mixing was associated with cooling of air temperature with an influx of cool rain and high rainfall. The underwater light penetration showed a similar pattern over the whole period with the highest in the red, and the lowest in the blue spectral region. Euphotic depth varied between 1.6 and 3.0 meters with the highest measurements corresponding to the stable stratification period. PO4-P concentrations ranged between 23 and 45 µg l–1 and NO3-N concentrations varied between 7 and 14 µg l–1 during the study period. Both nutrients showed increasing values associated with mixing periods and/or the rainy season.A total of 100 phytoplankton species were identified with 48% of the taxa represented by green algae, 30% by blue-green algae, 11% by diatoms, and the rest by chrysophytes, dinoflagellates, cryptomonads and euglenoids. The dominant phytoplankton species were Lyngbya nyassae, Botryococcus braunii and Microcystis species. Seasonal biomass variation was pronounced in the first two species but not in Mycrocystis. Phytoplankton biomass increased following the mixing period in December, and thermal destratification during May to July which was also a period with high rainfall and relatively high nutrient concentration. While the seasonal variation of the total phytoplankton community in Lake Awassa was relatively low (coefficient of variation < 20%), it was higher in some of the individual component species. 相似文献
18.
Phytoplankton of a humic and acidic lake in north eastern Quebec was studied during three years. Composition and succession are described. The biomass is very low and no distinct seasonal maximum was observed, the periodicity of various algal groups occurring in such a way that maximal populations succeed one another and do not co-exist.Contribution number 00 from Matamek Research Station 相似文献
19.
DIANA L. ENGLE JOHN M. MELACK† ROBERT D. DOYLE‡ THOMAS R. FISHER§ 《Global Change Biology》2008,14(2):369-381
We investigated whether rates of net primary production (NPP) and biomass turnover of floating grasses in a central Amazon floodplain lake (Lake Calado) are consistent with published evidence that CO2 emissions from Amazon rivers and floodplains are largely supplied by carbon from C4 plants. Ground‐based measurements of species composition, plant growth rates, plant densities, and areal biomass were combined with low altitude videography to estimate community NPP and compare expected versus observed biomass at monthly intervals during the aquatic growth phase (January–August). Principal species at the site were Oryza perennis (a C3 grass), Echinochloa polystachya, and Paspalum repens (both C4 grasses). Monthly mean daily NPP of the mixed species community varied from 50 to 96 g dry mass m?2 day?1, with a seasonal average (±1SD) of 64±12 g dry mass m?2 day?1. Mean daily NPP (±1SE) for P. repens and E. polystachya was 77±3 and 34±2 g dry mass m?2 day?1, respectively. Monthly loss rates of combined above‐ and below‐water biomass ranged from 31% to 75%, and averaged 49%. Organic carbon losses from aquatic grasses ranged from 30 to 34 g C m?2 day?1 from February to August. A regional extrapolation indicated that respiration of this carbon potentially accounts for about half (46%) of annual CO2 emissions from surface waters in the central Amazon, or about 44% of gaseous carbon emissions, if methane flux is included. 相似文献