scholarly journals The trophic role and impact of plankton ciliates in the microbial web structure of a tropical polymictic lake dominated by filamentous cyanobacteria

2016 ◽  
Vol 75 (s1) ◽  
Author(s):  
Alfonso Esquivel ◽  
Aude Barani ◽  
Miroslav Macek ◽  
Ruth Ruth Soto-Castor ◽  
Celia Bulit
Keyword(s):  
Food Web ◽  
Fish Larvae ◽  
Distribution Patterns ◽  
Freshwater Ecosystems ◽  
Trophic Levels ◽  
Epifluorescence Microscopy ◽  
Microbial Food Web ◽  
Filamentous Cyanobacteria ◽  
Subtropical Lakes ◽  
Ciliate Abundance

The recent interest in the plankton structures and dynamics in tropical and subtropical lakes has revealed important trends that set these lakes apart from temperate lakes, and one of the main differences is the enhanced importance of the microbial food web with respect to net plankton. Ciliates are a key component of subtropical and tropical microbial webs because of their role as dominant picoplankton grazers and their ability to channel picoplankton production to the uppermost trophic levels. Plankton ciliates have been found to play a crucial role in the survival of fish larvae in lakes that share several features with Lake Catemaco, a eutrophic tropical Mexican lake. Therefore, the plankton ciliate composition, abundance, and biomass of Lake Catemaco were studied to assess their role in the microbial food web. The data were obtained from surface and bottom water samples collected at eleven points during three surveys in 2011 and an additional survey in 2013, with the surveys covering the local climatic seasons. The most abundant components of the plankton ciliate assemblages were small prostomatids (<em>Urotricha </em>spp.), choreotrichs (<em>Rimostrombidium </em>spp.), cyclotrichs (<em>Mesodinium </em>and<em> Askenasia</em>), and scuticociliates (<em>Cyclidium, Cinetochilum, Pleuronema, </em>and <em>Uronema</em>). Other important ciliates in terms of abundance and/or biomass were haptorids (<em>Actinobolina, Belonophrya, Monodinium, Paradileptus, </em>and <em>Laginophrya</em>), <em>Halteria</em>, oligotrichs (<em>Limnostrombidium</em> and<em> Pelagostrombidium</em>), <em>Linostomella, Bursaridium, Cyrtolophosis,</em> and<em> Litonotus</em>. The ciliate abundance averaged 57 cells mL<sup>-1</sup> and ranged from 14 to 113 cells mL<sup>-1</sup>. The mean ciliate biomass was 71 µg C L<sup>-1</sup> and ranged from 10 to 202 µg C L<sup>-1</sup>. Differences were not detected in ciliate abundance or biomass between the sampling points or sampling depths (surface to bottom); however, significant differences were observed between seasons for both variables. Nano-sized filamentous cyanobacteria were the most abundant component of the plankton, and their abundance was assessed through epifluorescence microscopy counts. The autotrophic and heterotrophic picoplankton abundance was measured through epifluorescence, and their abundance and biomass were higher at the study site relative to other shallow freshwater ecosystems. The total ciliate biomass distribution patterns were similar to those of filamentous cyanobacteria and autotrophic or heterotrophic picoplankton, although the nanociliate biomasses peaked when the picoplankton and filamentous cyanobacteria were least abundant. The consequences of this increased importance of ciliates on the structure of the plankton at Lake Catemaco will be discussed along with the probable causes.

An Inverse Model Analysis of Planktonic Food Webs in Experimental Lakes

1994 ◽  
Vol 51 (9) ◽  
pp. 2034-2044 ◽  
Author(s):  
Alain F. Vézina ◽  
Michael L. Pace
Keyword(s):  
Food Web ◽  
Heterotrophic Bacteria ◽  
Grazing Pressure ◽  
Inverse Methods ◽  
Trophic Levels ◽  
Microbial Food Web ◽  
Food Web Structure ◽  
Planktonic Food ◽  
Size Groups ◽  
The Impact

We used inverse methods to reconstruct carbon flows in experimental lakes where the fish community had been purposely altered. These analyses were applied to three years of data from a reference lake and two experimental lakes located in Gogebic County, Michigan. We reconstructed seasonally averaged flows among two size groups of phytoplankton, heterotrophic bacteria, microzooplankton, cladocerans, and copepods. The inverse analysis produced significantly different flow networks for the different lakes that agreed qualitatively with known chemical and biological differences between lakes and with other analyses of the impact of fish manipulations on food web structure and dynamics. The results pointed to alterations in grazing pressure on the phytoplankton that parallel changes in the size and abundance of cladocerans and copepods among lakes. Estimated flows through the microbial food web indicated low bacterial production efficiencies and small carbon transfers from the microbial food web to the larger zooplankton. This study demonstrates the use of inverse methods to identify and compare flow patterns across ecosystems and suggests that microbial flows are relatively insensitive to changes at the upper trophic levels.

scholarly journals Trophic Patterns of Bighead Carp and Silver Carp Follow the Seasonality of Resource Availability

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1429
Author(s):  
Jia Yu ◽  
Jun Chen ◽  
Xuwei Deng ◽  
Zhixu Wu ◽  
Zuoming Yu ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Food Web ◽  
Trophic Level ◽  
Seasonal Variations ◽  
Silver Carp ◽  
Food Resources ◽  
Freshwater Ecosystems ◽  
Trophic Levels ◽  
Bighead Carp ◽  
Filter Feeding

The influence of seasonality of the aquatic environment on food web has been notoriously understudied in empirical ecology. In this study, we focus on seasonal changes in one key attribute of a food web, the trophic level. We determine whether seasonal variations of fish trophic levels could be indicated by the change in food resources. Silver carp (Hypophthalmichthys molitrix) and bighead carp (H. nobilis) were used to explore the responses of trophic levels of the filter-feeding fish to seasonal variations of food resources. Combined stable isotopic analysis and dietary analysis revealed that filter-feeding fish tended to have a higher trophic level in spring (May) and autumn (September and October). This may result from the abundant density of food resources (zooplankton and phytoplankton) and fish flexible foraging strategy, as we predicted that the trophic level follows the seasonality of food availability. Pearson’ correlation analysis and a structural equation model showed that seasonal variation of total phosphorus and water temperature could indirectly affect trophic levels of silver carp and bighead carp by mediating the abundance of phytoplankton and zooplankton directly and indirectly along the food chain. According to these findings, the seasonal variation of food resources could be an important indicator of the temporal dynamics of the food web trophic pattern in freshwater ecosystems.

Dominant aquatic species and their hydrological niches in freshwater ecosystems in a developing city

2019 ◽  
Vol 70 (5) ◽  
pp. 615
Author(s):  
S. Yang ◽  
T. Pan ◽  
X. Wang ◽  
Y. Sun ◽  
Y. Zhang ◽  
...  
Keyword(s):  
Food Web ◽  
Water Resource Management ◽  
Keystone Species ◽  
Aquatic Organisms ◽  
Freshwater Ecosystems ◽  
Trophic Levels ◽  
Food Web Structure ◽  
Spatial And Temporal Scales ◽  
Web Structure ◽  
Jinan City

Maintenance of appropriate hydrological niches is crucial to aquatic organisms. This study identified keystone species using the Ecopath with Ecosim food web model for hydrological niche analysis in Jinan City, the first pilot city of the Water Ecological Civilisation Project in China. The niche breadth of keystone species was analysed using Levins’ breadth model. Results revealed 35 keystone species in the aquatic ecosystems of Jinan City, including 5 phytoplankton, 7 zooplankton, 9 zoobenthos and 14 fish species. Streamflow was the most important hydrological factor affecting the phytoplankton, zooplankton, zoobenthos and fish communities in the study area, and excess variation in streamflow had an adverse effect on the normal evolution of the four biotic communities. We found that: (1) higher trophic levels in the food web contained more keystone species in the corresponding community; (2) carbon is an important element constraining the food web structure, and the magnitude of its effect on energy flow determines the degree of importance of the keystone species in the food web; and (3) changes to the survey season and at the spatiotemporal scale will have strong effects on the results of hydrological niche analysis and, to reduce these effects, it will be important to lengthen the spatial and temporal scales to cover both dry and flood seasons in the future. These results may provide an important basis for decision making regarding ecological scheduling and remediation of rivers in the study area, and potentially regions worldwide, thus facilitating aquatic ecological remediation and sustainable water resource management.

Fading out of the trophic cascade at the base of the microbial food web caused by changes in the grazing community in mesocosm experiments

2012 ◽  
Vol 41 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Iwona Jasser ◽  
Iwona Kostrzewska-Szlakowska
Keyword(s):  
Food Web ◽  
Trophic Cascade ◽  
Phytoplankton Community ◽  
Trophic Levels ◽  
Microbial Food Web ◽  
Lake District ◽  
Mesocosm Experiments ◽  
Experimental Mesocosms ◽  
Biomass Influence ◽  
Biomass Increase

AbstractBiomanipulation of consumer populations can have strong top-down impacts on the composition and biomass of lower trophic levels. In this paper, we assess how changes in crustaceans’ biomass influence classical grazing and the microbial food web in an oligo-mesohumic, low-pH lake (Mazurian Lake District, Poland). Removal of mesozooplankton from the experimental mesocosms created a gradient of crustacean biomass resulting in the biomass increase of rotifers, phytoplankton and protozooplankton, while autotrophic eukaryotic picoplankton (eu-APP) and bacteria were not affected. The strongest modifications concerned the rotifer biomass and phytoplankton community structure. Our results imply that the trophic cascade generated in the experiment did not extend to bacteria and eu-APP.

scholarly journals Temporal variability of the microbial food web (viruses to ciliates) under the influence of the Black Sea Water inflow (N. Aegean, E. Mediterranean)

2014 ◽  
Vol 15 (4) ◽  
pp. 769 ◽  
Author(s):  
A. GIANNAKOUROU ◽  
A. TSIOLA ◽  
M. KANELLOPOULOU ◽  
I. MAGIOPOULOS ◽  
I. SIOKOU ◽  
...  
Keyword(s):  
Food Web ◽  
Black Sea ◽  
Bacterial Production ◽  
Heterotrophic Bacteria ◽  
Sea Water ◽  
Phytoplankton Bloom ◽  
Aegean Sea ◽  
Trophic Levels ◽  
Microbial Food Web ◽  
The Black Sea

Τhe entire pelagic microbial food web was studied during the winter-spring period in the frontal area of the North Aegean Sea. Abundance of viruses, heterotrophic bacteria, cyanobacteria, auto- and hetero-trophic flagellates, and ciliates, as well as bacterial production, were measured at three stations (MD1, MD2, MD3) situated along a N-S transect between the area directly influenced by the inflowing Black Sea water and the area covered by the Levantine water. Samples were collected in December 2009, and January, March, April, and May 2011. Station MD1 exhibited the highest values of abundance and integrated biomass of all microbial groups and bacterial production during all months, and MD3 the lowest. Bacteria dominated the total integrated biomass at all stations and months, followed by cyanobacteria, auto-, hetero-trophic flagellates and ciliates. On a temporal scale, the microbial food web was less important in March as all microbial parameters at all stations showed the lowest values. After the phytoplankton bloom in March, the heterotrophic part of the microbial food web (mainly) strongly increased, though the intensity of the phenomenon was diminished from North to South. Pico-sized plankton was found to be heterotrophic whereas nanoplankton was autotrophic. It seems that the influence of the Black Sea water on station MD1, permanent throughout the study period of early winter to late spring, was reflected in all microbial populations studied, and produced a more productive pelagic food web system, with potential consequences for the upper trophic levels.

scholarly journals Microbial food web dynamics during spring phytoplankton blooms in the naturally iron-fertilized Kerguelen area (Southern Ocean)

2014 ◽  
Vol 11 (23) ◽  
pp. 6739-6753 ◽  
Author(s):  
U. Christaki ◽  
D. Lefèvre ◽  
C. Georges ◽  
J. Colombet ◽  
P. Catala ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Food Web ◽  
Bacterial Production ◽  
Trophic Levels ◽  
Microbial Food Web ◽  
Heterotrophic Nanoflagellates ◽  
Viral Production ◽  
Phytoplankton Blooms ◽  
Food Web Dynamics ◽  
Heterotrophic Production

Abstract. Microbial food web dynamics were determined during the onset of several spring phytoplankton blooms induced by natural iron fertilization off Kerguelen Island in the Southern Ocean (KEOPS2). The abundances of heterotrophic bacteria and heterotrophic nanoflagellates, bacterial heterotrophic production, bacterial respiration, and bacterial growth efficiency, were consistently higher in surface waters of the iron-fertilized sites than at the reference site in HNLC (high nutrient low chlorophyll) waters. The abundance of virus-like particles remained unchanged, but viral production increased by a factor of 6 in iron-fertilized waters. Bacterial heterotrophic production was significantly related to heterotrophic nanoflagellate abundance and viral production across all sites, with bacterial production explaining about 70 and 85%, respectively, of the variance of each in the mixed layer (ML). Estimated rates of grazing and viral lysis, however, indicated that heterotrophic nanoflagellates accounted for a substantially higher loss of bacterial production (50%) than viruses (11%). Combining these results with rates of primary production and export determined for the study area, a budget for the flow of carbon through the microbial food web and higher trophic levels during the early (KEOPS2) and the late phase (KEOPS1) of the Kerguelen bloom is provided.

scholarly journals How Microbial Food Web Interactions Shape the Arctic Ocean Bacterial Community Revealed by Size Fractionation Experiments

2021 ◽  
Vol 9 (11) ◽  
pp. 2378
Author(s):  
Oliver Müller ◽  
Lena Seuthe ◽  
Bernadette Pree ◽  
Gunnar Bratbak ◽  
Aud Larsen ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Food Web ◽  
Community Composition ◽  
Seasonal Changes ◽  
Bacterial Community Composition ◽  
Trophic Levels ◽  
The Arctic ◽  
Microbial Food Web ◽  
Small Scale ◽  
Size Fractionation

In the Arctic, seasonal changes are substantial, and as a result, the marine bacterial community composition and functions differ greatly between the dark winter and light-intensive summer. While light availability is, overall, the external driver of the seasonal changes, several internal biological interactions structure the bacterial community during shorter timescales. These include specific phytoplankton–bacteria associations, viral infections and other top-down controls. Here, we uncover these microbial interactions and their effects on the bacterial community composition during a full annual cycle by manipulating the microbial food web using size fractionation. The most profound community changes were detected during the spring, with ‘mutualistic phytoplankton’—Gammaproteobacteria interactions dominating in the pre-bloom phase and ‘substrate-dependent phytoplankton’—Flavobacteria interactions during blooming conditions. Bacterivores had an overall limited effect on the bacterial community composition most of the year. However, in the late summer, grazing was the main factor shaping the community composition and transferring carbon to higher trophic levels. Identifying these small-scale interactions improves our understanding of the Arctic marine microbial food web and its dynamics.

scholarly journals How trophic cascades and photic zone nutrient content interact to generate basin-scale differences in the microbial food web

2020 ◽  
Vol 77 (5) ◽  
pp. 1639-1647 ◽  
Author(s):  
T Frede Thingstad
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Trophic Cascades ◽  
Trophic Levels ◽  
Seasonal Migration ◽  
The Arctic ◽  
Microbial Food Web ◽  
Food Chains ◽  
Basin Scale ◽  
The Mediterranean

Abstract In linear food chains, resource and predator control produce positive and negative correlations, respectively, between biomass at adjacent trophic levels. These simple relationships become more complex in food webs that contain alternative food chains of unequal lengths. We have used a “minimum” model for the microbial part of the pelagic food web that has three such food chains connecting free mineral nutrients to copepods: via diatoms, autotrophic flagellates, and heterotrophic bacteria. Trophic cascades from copepods strongly modulates the balance between the three pathways and, therefore, the functionality of the microbial food web in services such as food production for higher trophic levels, DOM degradation, and ocean carbon sequestration. The result is a theoretical framework able to explain, not only apparent conflicts in Arctic mesocosm experiments, but also biogeochemical features of the Mediterranean. Here, the fundamental difference between Arctic and Mediterranean microbial food webs is the way they are predator driven by seasonal migration of large copepods in the Arctic, but resource driven due to the anti-estuarine circulation in the Mediterranean. In this framework, global change effects on microbial ecosystem functions are more like to come indirectly through changes in these drivers than through direct temperature effects on the microbes.

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