scholarly journals Changes in the Trophic Pathways within the Microbial Food Web in the Global Warming Scenario: An Experimental Study in the Adriatic Sea

2020 ◽  
Vol 8 (4) ◽  
pp. 510 ◽  
Author(s):  
Mladen Šolić ◽  
Danijela Šantić ◽  
Stefanija Šestanović ◽  
Natalia Bojanić ◽  
Slaven Jozić ◽  
...  
Keyword(s):  
Food Web ◽  
Growth Efficiency ◽  
Microbial Food Web ◽  
Recent Analysis ◽  
Functional Changes ◽  
Carbon Biomass ◽  
Trophic Pathways ◽  
Uptake Rates ◽  
Grazing Mortality ◽  
Global Warming Scenario

A recent analysis of the Mediterranean Sea surface temperature showed significant annual warming. Since small picoplankton microorganisms play an important role in all major biogeochemical cycles, fluxes and processes occurring in marine systems (the changes at the base of the food web) as a response to human-induced temperature increase, could be amplified through the trophic chains and could also significantly affect different aspects of the structure and functioning of marine ecosystems. In this study, manipulative laboratory growth/grazing experiments were performed under in situ simulated conditions to study the structural and functional changes within the microbial food web after a 3 °C increase in temperature. The results show that a rise in temperature affects the changes in: (1) the growth and grazing rates of picoplankton, (2) their growth efficiency, (3) carrying capacities, (4) sensitivity of their production and grazing mortality to temperature, (5) satisfying protistan grazer carbon demands, (6) their preference in the selection of prey, (7) predator niche breadth and their overlap, (8) apparent uptake rates of nutrients, and (9) carbon biomass flow through the microbial food web. Furthermore, temperature affects the autotrophic and heterotrophic components of picoplankton in different ways.

scholarly journals Warming effects on marine microbial food web processes: how far can we go when it comes to predictions?

2010 ◽  
Vol 365 (1549) ◽  
pp. 2137-2149 ◽  
Author(s):  
Hugo Sarmento ◽  
José M. Montoya ◽  
Evaristo Vázquez-Domínguez ◽  
Dolors Vaqué ◽  
Josep M. Gasol
Keyword(s):  
Food Web ◽  
Heterotrophic Bacteria ◽  
Dominant Role ◽  
Growth Efficiency ◽  
Microbial Food Web ◽  
Central Position ◽  
Labile Organic Matter ◽  
Theoretical Predictions ◽  
Spatio Temporal ◽  
Bacterial Grazer

Previsions of a warmer ocean as a consequence of climatic change point to a 2–6°C temperature rise during this century in surface oceanic waters. Heterotrophic bacteria occupy the central position of the marine microbial food web, and their metabolic activity and interactions with other compartments within the web are regulated by temperature. In particular, key ecosystem processes like bacterial production (BP), respiration (BR), growth efficiency and bacterial–grazer trophic interactions are likely to change in a warmer ocean. Different approaches can be used to predict these changes. Here we combine evidence of the effects of temperature on these processes and interactions coming from laboratory experiments, space-for-time substitutions, long-term data from microbial observatories and theoretical predictions. Some of the evidence we gathered shows opposite trends to warming depending on the spatio-temporal scale of observation, and the complexity of the system under study. In particular, we show that warming (i) increases BR, (ii) increases bacterial losses to their grazers, and thus bacterial–grazer biomass flux within the microbial food web, (iii) increases BP if enough resources are available (as labile organic matter derived from phytoplankton excretion or lysis), and (iv) increases bacterial losses to grazing at lower rates than BP, and hence decreasing the proportion of production removed by grazers. As a consequence, bacterial abundance would also increase and reinforce the already dominant role of microbes in the carbon cycle of a warmer ocean.

scholarly journals Food Web Structure and Trophic Interactions Revealed by Stable Isotope Analysis in the Midstream of the Chishui River, a Tributary of the Yangtze River, China

Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 195
Author(s):  
Qiang Qin ◽  
Fubin Zhang ◽  
Fei Liu ◽  
Chunling Wang ◽  
Huanzhang Liu
Keyword(s):  
Stable Isotope ◽  
Carbon Source ◽  
Food Web ◽  
Food Chain ◽  
Yangtze River ◽  
Trophic Niche ◽  
The Yangtze River ◽  
Food Chain Length ◽  
Trophic Pathways ◽  
Chishui River

Understanding energy flow and nutrient pathways is crucial to reveal the dynamics and functions of riverine ecosystems and develop appropriate conservation strategies. In this study, we utilized stable isotopes of δ13C and δ15N to examine the fundamental characteristics of trophic position, trophic niche, and carbon source for the food web in the midstream of the Chishui River, a tributary to the Yangtze River. Our results showed that stable isotope signatures among different sorts of basal resources and consumers were significantly distinguishable and that the food chain consisted of four trophic levels, indicating the multiple trophic pathways and long food chain length here. The trophic guilds of fish were classified into four categories, in which herbivorous and carnivorous fish showed greater trophic diversity and omnivorous fish had higher trophic redundancy, which meant that there was a stable trophic niche structure in the study area. Phytoplankton and periphyton presented the largest contributions to consumers, indicating that autochthonous productivity was the dominant carbon source in the midstream of the Chishui River. Since the Chishui River is still in a natural condition without any dam constructions, the autochthonous productivity, stable trophic niche structure, multiple trophic pathways and long food chain length found here demonstrate its high conservation value. Therefore, the strategy to refrain from damming on this river should persist into the future.

scholarly journals Enhanced Viral Activity in the Surface Microlayer of the Arctic and Antarctic Oceans

2021 ◽  
Vol 9 (2) ◽  
pp. 317
Author(s):  
Dolors Vaqué ◽  
Julia A. Boras ◽  
Jesús Maria Arrieta ◽  
Susana Agustí ◽  
Carlos M. Duarte ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Food Web ◽  
Physicochemical Characteristics ◽  
The Arctic ◽  
Microbial Food Web ◽  
Surface Microlayer ◽  
Polar Regions ◽  
Nutrient Inputs ◽  
Viral Activity ◽  
The Impact

The ocean surface microlayer (SML), with physicochemical characteristics different from those of subsurface waters (SSW), results in dense and active viral and microbial communities that may favor virus–host interactions. Conversely, wind speed and/or UV radiation could adversely affect virus infection. Furthermore, in polar regions, organic and inorganic nutrient inputs from melting ice may increase microbial activity in the SML. Since the role of viruses in the microbial food web of the SML is poorly understood in polar oceans, we aimed to study the impact of viruses on prokaryotic communities in the SML and in the SSW in Arctic and Antarctic waters. We hypothesized that a higher viral activity in the SML than in the SSW in both polar systems would be observed. We measured viral and prokaryote abundances, virus-mediated mortality on prokaryotes, heterotrophic and phototrophic nanoflagellate abundance, and environmental factors. In both polar zones, we found small differences in environmental factors between the SML and the SSW. In contrast, despite the adverse effect of wind, viral and prokaryote abundances and virus-mediated mortality on prokaryotes were higher in the SML than in the SSW. As a consequence, the higher carbon flux released by lysed cells in the SML than in the SSW would increase the pool of dissolved organic carbon (DOC) and be rapidly used by other prokaryotes to grow (the viral shunt). Thus, our results suggest that viral activity greatly contributes to the functioning of the microbial food web in the SML, which could influence the biogeochemical cycles of the water column.

Modeling the microbial food web

1994 ◽  
Vol 28 (2) ◽  
pp. 303-319 ◽  
Author(s):  
H. W. Ducklow
Keyword(s):  
Food Web ◽  
Microbial Food Web

Abundance and Community Structure of Picoplankton and Protists in the Microbial Food Web of Barguzin Bay, Lake Baikal

2005 ◽  
Vol 39 (3) ◽  
pp. 263-270 ◽  
Author(s):  
Hiroyuki Ueno ◽  
Toshiya Katano ◽  
Shin-Ichi Nakano ◽  
Osamu Mitamura ◽  
Kaori Anbutsu ◽  
...  
Keyword(s):  
Community Structure ◽  
Food Web ◽  
Lake Baikal ◽  
Microbial Food Web

scholarly journals Trophic structure of a nektobenthic community exploited by a multispecific bottom trawling fishery in Northeastern Brazil

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246491
Author(s):  
Alex Souza Lira ◽  
Flávia Lucena-Frédou ◽  
Frédéric Ménard ◽  
Thierry Frédou ◽  
Júlio Guazzelli Gonzalez ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Food Web ◽  
Benthic Invertebrates ◽  
Trophic Structure ◽  
Fish Fauna ◽  
Cumulative Effects ◽  
Northeastern Brazil ◽  
Population Parameters ◽  
Bottom Trawling ◽  
Trophic Pathways

We used complementary stable isotope (SIA) and stomach content (SCA) analyses to investigate feeding relationships among species of the nektobenthic communities and the potential ecological effects of the bottom trawling of a coastal ecosystem in northeastern Brazil. Carbon (δ13C) and nitrogen (δ15N) compositions were determined for five basal sources and 28 consumers, from zooplankton to shrimp and fish species. Fishes and basal sources showed a broad range of δ15N (fishes: 6.49–14.94‰; sources: 2.58–6.79‰) and δ13C values (fishes: -23.86 to -13.71‰; sources: -24.32 to -13.53‰), while shrimps and crabs exhibited similar nitrogen and carbon ratios. Six trophic consumer groups were determined among zooplankton, crustaceans and fishes by SIA, with trophic pathways associated mostly with benthic sources. SCA results indicated a preference for benthic invertebrates, mainly worms, crabs and shrimps, as prey for the fish fauna, highlighting their importance in the food web. In overall, differences between SCA and the SIA approaches were observed, except for groups composed mainly for shrimps and some species of high δ15N values, mostly piscivorous and zoobenthivores. Given the absence of regulation for bottom trawling activities in the area, the cumulative effects of trawling on population parameters, species composition, potentially decreasing the abundance of benthic preys (e.g., shrimps, worms and crabs) may lead to changes in the trophic structure potentially affect the food web and the sustainability of the fishery.

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