Changes in the planktonic food web of a new experimental reservoir

1997 ◽  
Vol 54 (5) ◽  
pp. 1088-1102 ◽  
Author(s):  
M J Paterson ◽  
D Findlay ◽  
K Beaty ◽  
W Findlay ◽  
E U Schindler ◽  
...  
Keyword(s):  
Organic Matter ◽  
Bacterial Biomass ◽  
Zooplankton Community ◽  
Zooplankton Biomass ◽  
Phytoplankton Production ◽  
First Year ◽  
Terrestrial Vegetation ◽  
Terrestrial Organic Matter ◽  
Planktonic Food ◽  
Before And After

Changes in plankton community structure were examined in an experimental reservoir (Lake 979) before and after impoundment. The role of allochthonous organic matter in planktonic food webs is unclear, and reservoir creation can be viewed as an extreme manipulation of terrestrial organic matter inputs. After impoundment of Lake 979, concentrations of phosphorus, nitrogen, and dissolved organic carbon increased as a result of decomposition of flooded terrestrial organic matter. In the first year of impoundment, mean bacterial biomass increased 10 times , and individual bacterial cell volumes increased 2 times over pre-flooding averages. Phytoplankton production and biomass decreased to approximately 25% of pre-flooding levels. Zooplankton biomass and production by Cladocera increased 10 times , and zooplankton community composition changed from dominance by small-sized Bosmina longirostris to dominance by large Daphnia rosea. In the first year of impoundment, production by Cladocera usually exceeded phytoplankton14C productivity, suggesting that the main pathway of carbon flow to secondary producers shifted from an autochthonous to an allochthonous base derived from flooded terrestrial vegetation. In the second year of flooding, bacterial biomass decreased and phytoplankton biomass was higher than in the two previous years of study.

scholarly journals Copepods act as omnivores in a (sub)tropical reservoir: Implication for the top-down effect on phytoplankton

2018 ◽  
Vol 77 (2) ◽  
Author(s):  
Qiuqi Lin ◽  
Liang Peng ◽  
Yang Yang ◽  
Bo-Ping Han
Keyword(s):  
Organic Matter ◽  
Trophic Position ◽  
Zooplankton Community ◽  
Nitrogen Isotope ◽  
Terrestrial Organic Matter ◽  
Tropical Reservoir ◽  
Cascading Effect ◽  
Cladoceran Species ◽  
Grazing Effect ◽  
One Year

Tropical reservoirs in China receive a high input of organic matter from surrounding watersheds and this represents a significant resource for zooplankton consumers. Copepods are often the dominant zooplankton group in the tropical systems. Whether copepods tend to be omnivorous and their potential cascading effect on phytoplankton are subjects of debate. We used stable carbon and nitrogen isotope analyses to elucidate the allochthony and trophic positions of two copepod species (Phyllodiaptomus tunguidus and Mesocyclops thermocyclopoides) and one cladoceran species (Diaphanosoma orghidani) over a one-year period in a tropical oligo-mesotrophic reservoir in China. We assumed the filter-feeding D. orghidani was herbivorous and we used it as a baseline indicator of δ15N to estimate the trophic position of the two copepods. P. tunguidus and M. thermocyclopoides had an average trophic level that was 0.7 and 0.5 higher, respectively, than that of D. orghidani. M. thermocyclopoides showed seasonal differences in trophic position and an increase in trophic position with rising temperatures, whereas P. tunguidus remained omnivorous throughout the year. All three zooplankton species had a much higher degree of allochthony in the flood season than in the dry season, and their allochthony was positively related to the allochthony of the particulate organic matter input. The two copepods’ omnivorous behavior suggests their allochthony was primarily linked to microbial food web based on the input of terrestrial organic matter. The chlorophyll a to total phosphorus ratio was much higher when P. tunguidus dominated the zooplankton community than when D. orghidani dominated. The ratio was positively related to the ratio of omnivorous adult copepods to cladoceran biomass but not to the zooplankton:phytoplankton biomass ratio. Our results suggest that copepods tended to be omnivorous and relied heavily on allochthonous material in the study reservoir. The indirect cascading effect is likely to be stronger than the direct grazing effect, resulting in a positive effect of copepods on the phytoplankton.

scholarly journals Stream Macroinvertebrates and Carbon Cycling in Tangled Food Webs

Ecosystems ◽  
2021 ◽  
Author(s):  
Benoît O. L. Demars ◽  
Joanna L. Kemp ◽  
Baptiste Marteau ◽  
Nikolai Friberg ◽  
Barry Thornton
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Food Web ◽  
Food Webs ◽  
Carbon Sources ◽  
Terrestrial Ecosystems ◽  
Terrestrial Organic Matter ◽  
Before And After ◽  
Reference Stream ◽  
Induced Changes

AbstractThe annual global loss of organic carbon from terrestrial ecosystems into rivers is similar to the organic carbon stored in soils each year. Dissolved organic matter (DOM) flows through the food web to macroinvertebrates, but little is known about the effect of DOM increase on stream food webs and how much macroinvertebrates may contribute to the regulation of carbon fluxes in rivers. Using a before and after control impact (BACI) experimental design, we increased by 12% (+ 0.52 mg C L−1) the concentration of DOM in a stream for three weeks by adding sucrose, with a distinctive δ13C signature, to simulate a pulse of natural DOM supply from soils. We partitioned the diet of macroinvertebrates from carbon sources according to the green pathway (autotrophs) and detrital pathways (bacteria and terrestrial organic matter). Our flow food web approach based on C fluxes, with bacteria as a key node, showed the dominant contribution of the detrital pathways for macroinvertebrates in the reference stream. DOM addition induced changes in the diets of individual taxa, but did not have any strong effects on the relative overall contribution of the detrital pathways versus the green pathway. Autotrophic uptake of CO2 respired by bacteria was much larger than bacterial C flux to invertebrates (that is, the classic microbial loop) and allowed a significant fraction of natural allochthonous organic carbon to make its way to macroinvertebrates via autotrophs fixing CO2 respired by bacteria. Overall macroinvertebrates did not regulate directly to any great extent the flux of stream DOM towards downstream ecosystems.

scholarly journals Intra-annual variability of carbon and nitrogen stable isotopes in suspended organic matter in waters of the western continental shelf of India

2011 ◽  
Vol 8 (11) ◽  
pp. 3441-3456 ◽  
Author(s):  
M. V. Maya ◽  
S. G. Karapurkar ◽  
H. Naik ◽  
R. Roy ◽  
D. M. Shenoy ◽  
...  
Keyword(s):  
Organic Matter ◽  
Continental Shelf ◽  
Phytoplankton Production ◽  
Terrestrial Organic Matter ◽  
Monsoon Period ◽  
Isotopic Signatures ◽  
Carbon And Nitrogen ◽  
Annual Variability ◽  
Post Monsoon ◽  
Sw Monsoon

Abstract. Intra-annual variations of δ13C and δ15N of water-column suspended particulate organic matter (SPOM) have been investigated to understand the biogeochemical cycling of C and N in the Western Continental Shelf of India (WCSI). The key issues being addressed are: how the δ15N of SPOM is affected by seasonally varying processes of organic matter production and respiration and how it relates to the δ15N of sedimentary organic matter that appears to show a decreasing trend despite an apparent intensification of seasonal oxygen deficiency over the past few decades? A secondary objective was to evaluate the sources of organic carbon. Elemental carbon and nitrogen concentrations, C/N ratios in SPOM, along with ancillary chemical and biological variables including phytoplankton pigment abundance were also determined on a seasonal basis (from March 2007 to September 2008), with the partial exception of the southwest (SW) monsoon period. The results reveal significant shifts in isotopic signatures, especially δ15N, of SPOM before and after the onset of SW monsoon. Very low δ15N values, reaching a minimum of −4.17 ‰, are found during the pre-monsoon period. Our results provide the first direct evidence for the addition of substantial amounts of isotopically light nitrogen by the diazotrophs, especially Trichodesmium, in the region. The δ15N of SPOM is generally lower than the mean value (7.38 ‰) for surficial sediments, presumably because of diagenetic enrichment. The results support the view that sedimentary δ15N may not necessarily reflect denitrification intensity in the overlying waters due to diverse sources of nitrogen and variability of its isotopic composition. The observed intra-annual variability of δ13C of SPOM during the pre-monsoon and post-monsoon periods is generally small. Phytoplankton production and probably species composition could drive some of the observed changes. The largest changes (depletion of δ13C and increase in C/N) appear to occur during the pre- and post-monsoon seasons, presumably through episodic deposition of terrestrial organic matter from the atmosphere. During the SW monsoon, when a large input of terrestrial organic matter is expected through runoff from land, the C/N ratio remains low, but significant difference is observed between δ13C data in 2007 and 2008. Inputs of soil organic matter that may have elemental and isotopic signatures different from those of the conventional (C3 plant derived) organic matter could explain the constancy of the C/N ratio.

Carbon isotope fluctuations of terrestrial organic matter for the Upper Cretaceous (Cenomanian–Santonian) in the Obira area of Hokkaido, Japan

2009 ◽  
Vol 146 (5) ◽  
pp. 761-774 ◽  
Author(s):  
GO-ICHIRO URAMOTO ◽  
YOSHIHIRO ABE ◽  
HIROMICHI HIRANO
Keyword(s):  
Organic Matter ◽  
Carbon Isotope ◽  
Upper Cretaceous ◽  
Global Scale ◽  
Terrestrial Vegetation ◽  
Terrestrial Organic Matter ◽  
Global Correlation ◽  
Marine Carbonate ◽  
Marine Carbonates ◽  
Carbon Reservoir

AbstractStratigraphic fluctuations of carbon isotope values of terrestrial organic matter within the Upper Cretaceous (Cenomanian–Santonian) sequence in the Obira area of Hokkaido, Japan, record distinctive δ13C fluctuations for the Cenomanian–Turonian boundary, the Middle Turonian, the upper Turonian–lower Coniacian, and the Santonian. A biostratigraphic framework of the age-diagnostic taxa (ammonoids, bivalves and planktic foraminifers) indicates that these δ13C fluctuation events are comparable with those recorded in δ13C data of terrestrial organic matter in Japan and marine carbonates in Europe. These correlations reinforce the utility of these δ13C events in terms of global chemostratigraphy. In particular, the δ13C patterns within the overall positive interval of the Cenomanian–Turonian boundary event are highly conformable between marine and terrestrial records. The consistent nature of these different records of δ13C fluctuation patterns demonstrates that the terrestrial organic δ13C data mirror the global-scale δ13C patterns in the carbon reservoir of ocean–atmosphere–terrestrial biosphere during the Cenomanian–Turonian boundary event. In addition, global correlation of short-term marine and terrestrial organic δ13C fluctuations of the Upper Cretaceous sequence indicate that the magnitude of several terrestrial organic δ13C events appears more amplified than that of coeval marine carbonate δ13C events. This correlation is interpreted to mean that the effects of local CO2 emission into the atmosphere by release of terrestrial methane hydrate or biomass burning of terrestrial vegetation in the hinterland of the NE Asian region have been superimposed on the global δ13C trend and resulted in the terrestrial organic δ13C records of the Yezo Group.

scholarly journals Indirect Effects of Copper Sulfate Addition on Zooplankton Communities in Ohio Upground Reservoirs

2015 ◽  
Vol 115 (2) ◽  
pp. 24 ◽  
Author(s):  
Meghan C.W. Williams ◽  
Joseph D. Conroy ◽  
Jeffrey G. Miner ◽  
John R. Farver
Keyword(s):  
Water Supply ◽  
Copper Sulfate ◽  
Yellow Perch ◽  
Zooplankton Community ◽  
Zooplankton Biomass ◽  
Negative Effects ◽  
Small Copepod ◽  
Before And After ◽  
Zooplankton Communities ◽  
Sport Fish

Municipal water managers use copper sulfate (CuSO4) to control algae, predominantly phytoplankton, in water supply reservoirs. In multiple-purpose upground reservoirs in northwestern Ohio, CuSO4 application regimens vary from no application to over 600 µg Cu/L/year. Whereas CuSO4 effectively suppresses phytoplankton growth, it also has documented toxicities to zooplankton, which serve as forage for stocked sport fish. Consequently, CuSO4 application benefits one upground reservoir use (water supply) while potentially negatively affecting another (sport fishing). This research sought to directly compare copper concentrations ([Cu]) in dissolved and particulate fractions with corresponding zooplankton community composition and abundance both before and after CuSO4 application in Ohio upground reservoirs. Copper concentrations and zooplankton community characters were measured at four upground reservoirs (n = 2 treated with CuSO4 and n = 2 untreated) over multiple weeks during summer 2010. Total [Cu] in treated reservoirs increased by as much as 428% from pre- (mean = 16.5 µg/L) to post-application (mean = 70.7 µg/L); concomitantly, zooplankton biomass and density decreased by as much as 93%. Post-application zooplankton communities shifted to dominance by small copepod nauplii from a mixed community that included larger cladocerans. Copepod nauplii represent a less-suitable food source for stocked juvenile yellow perch Perca flavescens. Thus, short-term negative effects to the zooplankton community may result from CuSO4 applications, indirectly affecting stocked sport fish success.

scholarly journals Effects of thermocline deepening on lake plankton communities

2011 ◽  
Vol 68 (2) ◽  
pp. 260-276 ◽  
Author(s):  
Ariane Cantin ◽  
Beatrix E. Beisner ◽  
John M. Gunn ◽  
Yves T. Prairie ◽  
Jennifer G. Winter
Keyword(s):  
Taxonomic Composition ◽  
Zooplankton Biomass ◽  
Phytoplankton Production ◽  
Thermocline Depth ◽  
Turbulent Environments ◽  
Planktonic Food ◽  
Basin Scale ◽  
Zooplankton Communities ◽  
The Vertical Distribution ◽  
Plankton Communities

Theory predicts, and some evidence demonstrates that in lakes, the depth of the thermocline can have a large structural influence on the spatial distribution, and strongly influences the composition of plankton communities. However, experimental assessments of responses of the planktonic food web to thermocline depth have not yet been done at the whole-basin scale. We conducted an experiment wherein we artificially lowered the thermocline in an isolated basin of a three-basin lake, maintaining another isolated basin as a control. The vertical distribution and taxonomic composition of both phytoplankton and zooplankton were monitored throughout the summer months. Greater phytoplankton production, especially in the epilimnion, attributable mainly to increases in the chlorophytes was observed with thermocline deepening, but at the deepest thermoclines, production was limited. Total zooplankton biomass was unaffected by thermocline depth, suggesting top-down control by predators. Zooplankton biomass peaks were less pronounced in the manipulated basin, but tended to follow the thermocline whether at its normal position or as it was deepened. Zooplankton composition was significantly altered by large increases in densities of predatory cyclopoid copepods and rotifers; taxa commonly found in turbulent environments. Overall, both phytoplankton and zooplankton communities demonstrated important shifts in structure and composition in response to thermocline deepening.

Environmental relevance of adsorption of doxycycline, enrofloxacin, and sulfamethoxypyridazine before and after the removal of organic matter from soils

2021 ◽  
Vol 287 ◽  
pp. 112354
Author(s):  
C. Alvarez-Esmorís ◽  
M. Conde-Cid ◽  
M.J. Fernández-Sanjurjo ◽  
A. Núñez-Delgado ◽  
E. Álvarez-Rodríguez ◽  
...  
Keyword(s):  
Organic Matter ◽  
Before And After ◽  
Environmental Relevance
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