Bottom-up and top-down controls of the microbial food web in the Southern Ocean: experiments with manipulated microcosms

Polar Biology ◽  
1992 ◽  
Vol 12 (2) ◽  
Author(s):  
Jorma Kuparinen ◽  
PeterK. Bj�rnsen
Keyword(s):  
Southern Ocean ◽  
Food Web ◽  
Microbial Food Web ◽  
Top Down ◽  
Bottom Up

Trophic Relationships in Freshwater Pelagic Ecosystems

1986 ◽  
Vol 43 (8) ◽  
pp. 1571-1581 ◽  
Author(s):  
Donald J. McQueen ◽  
John R. Post ◽  
Edward L. Mills
Keyword(s):  
Food Web ◽  
Trophic Status ◽  
Size Structure ◽  
Trophic Relationships ◽  
Top Down ◽  
Eutrophic Lakes ◽  
Bottom Up ◽  
Coefficients Of Variation ◽  
Step Down ◽  
Pelagic Ecosystems

Relative impacts of bottom-up (producer controlled) and top-down (consumer controlled) forces on the biomass and size structure of five major components of freshwater pelagic systems (piscivores, planktivores, zooplankton, phytoplankton, and total phosphorus availability) were estimated. Predictions that emerge are (1) maximum biomass at each trophic level is controlled from below (bottom-up) by nutrient availability, (2) this bottom-up regulation is strongest at the bottom of the food web (i.e. phosphorus → phytoplankton) and weakens by a factor of 2 with each succeeding step up the food web, (3) as energy moves up a food web, the predictability of bottom-up interactions decreases, (4) near the top of the food web, top-down (predator mediated) interactions are strong and have low coefficients of variation, but weaken with every step down the food web, (5) variability around the bottom-up regressions can always be explained by top-down forces, and (6) interplay between top-down and bottom-up effects changes with the trophic status of lakes. In eutrophic lakes, top-down effects are strong for piscivore → zooplankton, weaker for planktivore → zooplankton, and have little impact for zooplankton → phytoplankton. For oligotrophic lakes, the model predicts that top-down effects are not strongly buffered, so that zooplankton → phytoplankton interactions are significant.

scholarly journals Interpreting variation in fish-based food web indicators: the importance of “bottom-up limitation” and “top-down control” processes

2013 ◽  
Vol 71 (2) ◽  
pp. 406-416 ◽  
Author(s):  
T. O. M. Reilly ◽  
H. M. Fraser ◽  
R. J. Fryer ◽  
J. Clarke ◽  
S. P. R. Greenstreet
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Trophic Levels ◽  
Top Down ◽  
Bottom Up ◽  
Control Processes ◽  
Top Predators ◽  
Environmental Status ◽  
Fish Predators ◽  
Firth Of Forth

Abstract Reilly, T. O. M., Fraser, H. M., Fryer, R. J., Clarke, J., and Greenstreet, S. P. R. 2014. Interpreting variation in fish-based food web indicators: the importance of “bottom-up limitation” and “top-down control” processes. – ICES Journal of Marine Science, 71: 406–416. Proposed indicators for the Marine Strategy Framework Directive (MSFD) food webs Descriptor focus on structural elements of food webs, and in particular on the abundance and productivity of top predators. However, the inferences that can be drawn from such indicators depend on whether or not the predators are “bottom-up limited” by the availability of their prey. Many seabird populations appear to be “bottom-up limited” so that variation in their reproductive success and/or abundance reflects changes in lower trophic levels. Here we find that gadoid fish predators off the Firth of Forth, southeast Scotland, do not appear to be “bottom-up limited” by the biomass of their main prey, 0-group sandeels; gadoid biomass and feeding performance was independent of sandeel biomass. Variability in food web indicators based on these gadoid predators seems to impart little insight into underlying processes occurring at lower trophic levels in the local food web. The implications of this in terms of how the currently proposed MSFD food web indicators should be used and interpreted are considered, and the ramifications in terms of setting targets representing good environmental status for both fish and seabird communities are discussed.

scholarly journals Coupling of the spatial dynamic of picoplankton and nanoflagellate grazing pressure and carbon flow of the microbial food web in the subtropical pelagic continental shelf ecosystem

2013 ◽  
Vol 10 (1) ◽  
pp. 233-263 ◽  
Author(s):  
K.-P. Chiang ◽  
A.-Y. Tsai ◽  
P.-J. Tsai ◽  
G.-C. Gong ◽  
S.-F. Tsai
Keyword(s):  
Growth Rate ◽  
Food Web ◽  
Heterotrophic Bacteria ◽  
Microbial Food Web ◽  
Size Fractionation ◽  
Pelagic Ecosystem ◽  
Active Growth ◽  
Bottom Up ◽  
Bacteria Growth ◽  
Oligotrophic Ecosystem

Abstract. In order to investigate the mechanism of spatial dynamics of picoplankton community (bacteria and Synechococcus spp.) and estimate the carbon flux of the microbial food web in the oligotrophic Taiwan Warm Current Water of subtropical marine pelagic ecosystem, we conducted size-fractionation experiments in five cruises by the R/V Ocean Research II during the summers of 2010 and 2011 in the southern East China Sea. We carried out culture experiments using surface water which, according to a temperature-salinity (T-S) diagram, is characterized as oligotrophic Taiwan Current Warm Water. We found a negative correlation bettween bacteria growth rate and temperature, indicating that the active growth of heterotrophic bacteria might be induced by nutrients lifted from deep layer by cold upwelling water. This finding suggests that the area we studied was a bottom-up control pelagic ecosystem. We suggest that the microbial food web of an oligotrophic ecosystem may be changed from top-down control to resource supply (bottom-up control) when a physical force brings nutrient into the oligotrophic ecosystem. Upwelling brings nutrient-rich water to euphotic zone and promotes bacteria growth, increasing the picoplankton biomass which increased the consumption rate of nanoflagellate. The net growth rate (growth rate–grazing rate) becomes negative when the densities of bacteria and Synechococcus spp. are lower than the threshold values. The interaction between growth and grazing will limit the abundances of bacteria (105-106 cells mL-1 and Synechococcus spp. (104-105 cells mL-1) within a narrow range, forming a predator-prey eddy. Meanwhile, 62% of bacteria production and 55% of Synechococcus spp. production are transported to higher trophic level (nanoflagellate), though the cascade effect might cause an underestimation of both percentages of transported carbon. Based on the increasing number of sizes we found in the size-fractionation experiments, we estimated that the predation values were underestimated by 28.3% for bacteria and 34.6% for Synechococcus spp. Taking these corrections into consideration, we conclude that picoplankton production is balanced by nonoflagellate grazing and the diet of nanoflagellate is composed of 64% bacteria and 36% Synechococcus spp.

scholarly journals The meaning of functional trait composition of food webs for ecosystem functioning

2016 ◽  
Vol 371 (1694) ◽  
pp. 20150268 ◽  
Author(s):  
Dominique Gravel ◽  
Camille Albouy ◽  
Wilfried Thuiller
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Functional Diversity ◽  
Ecosystem Functioning ◽  
Functional Trait ◽  
Plant Ecology ◽  
Functional Composition ◽  
Top Down ◽  
Bottom Up ◽  
Functional Trait Diversity

There is a growing interest in using trait-based approaches to characterize the functional structure of animal communities. Quantitative methods have been derived mostly for plant ecology, but it is now common to characterize the functional composition of various systems such as soils, coral reefs, pelagic food webs or terrestrial vertebrate communities. With the ever-increasing availability of distribution and trait data, a quantitative method to represent the different roles of animals in a community promise to find generalities that will facilitate cross-system comparisons. There is, however, currently no theory relating the functional composition of food webs to their dynamics and properties. The intuitive interpretation that more functional diversity leads to higher resource exploitation and better ecosystem functioning was brought from plant ecology and does not apply readily to food webs. Here we appraise whether there are interpretable metrics to describe the functional composition of food webs that could foster a better understanding of their structure and functioning. We first distinguish the various roles that traits have on food web topology, resource extraction (bottom-up effects), trophic regulation (top-down effects), and the ability to keep energy and materials within the community. We then discuss positive effects of functional trait diversity on food webs, such as niche construction and bottom-up effects. We follow with a discussion on the negative effects of functional diversity, such as enhanced competition (both exploitation and apparent) and top-down control. Our review reveals that most of our current understanding of the impact of functional trait diversity on food web properties and functioning comes from an over-simplistic representation of network structure with well-defined levels. We, therefore, conclude with propositions for new research avenues for both theoreticians and empiricists.

Bottom-up carbon subsidies and top-down predation pressure interact to affect aquatic food web structure

Oikos ◽  
2010 ◽  
Vol 120 (2) ◽  
pp. 311-320 ◽  
Author(s):  
C. L. Faithfull ◽  
M. Huss ◽  
T. Vrede ◽  
A.-K. Bergström
Keyword(s):  
Food Web ◽  
Predation Pressure ◽  
Aquatic Food Web ◽  
Top Down ◽  
Food Web Structure ◽  
Bottom Up ◽  
Web Structure ◽  
Aquatic Food

Microbial food web structure in a naturally iron-fertilized area in the Southern Ocean (Kerguelen Plateau)

2008 ◽  
Vol 55 (5-7) ◽  
pp. 706-719 ◽  
Author(s):  
U. Christaki ◽  
I. Obernosterer ◽  
F. Van Wambeke ◽  
M. Veldhuis ◽  
N. Garcia ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Food Web ◽  
Microbial Food Web ◽  
Kerguelen Plateau ◽  
Food Web Structure ◽  
Web Structure

scholarly journals Latitudinal variation in top-down and bottom-up control of a salt marsh food web

Ecology ◽  
2011 ◽  
Vol 92 (2) ◽  
pp. 276-281 ◽  
Author(s):  
L. B. Marczak ◽  
C.-K. Ho ◽  
K. Więski ◽  
H. Vu ◽  
R. F. Denno ◽  
...  
Keyword(s):  
Salt Marsh ◽  
Food Web ◽  
Latitudinal Variation ◽  
Top Down ◽  
Bottom Up

scholarly journals Alteration of coastal productivity and artisanal fisheries interact to affect a marine food-web

2020 ◽  
Author(s):  
M. Isidora Ávila-Thieme ◽  
Derek Corcoran ◽  
Alejandro Pérez-Matus ◽  
Evie A. Wieters ◽  
Sergio A. Navarrete ◽  
...  
Keyword(s):  
Climate Change ◽  
Food Web ◽  
Artisanal Fisheries ◽  
Top Down ◽  
Bottom Up ◽  
Predator Species ◽  
Marine Food Web ◽  
Productivity Decline ◽  
Marine Food ◽  
Negative Impacts

ABSTRACTTop-down and bottom-up forces determine ecosystem function and dynamics. Fisheries as a top-down force can shorten and destabilize food-webs, while climate-change driven effects can alter the bottom-up forces of primary productivity. We assessed the response of a highly-resolved intertidal food-web to these two global-change drivers, using network analysis and bioenergetic modelling. We quantified the relative importance of artisanal fisheries as another predator species, and evaluated the independent and combined effects of fisheries and plankton-productivity changes on food-web dynamics. The food-web was robust to the loss of all harvested species but sensible to plankton-productivity decline. Interestingly, fisheries dampened the negative impacts of decreasing plankton productivity on non-harvested species, while plankton-productivity decline increased the sensitivity of harvested species to fishing. Our results show that strategies for new scenarios caused by climate change are needed to protect marine ecosystems and the wellbeing of local communities dependent on their resources.

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