Network trophic dynamics: the modes of energy utilization in ecosystems

Higashi, Masahiko; Patten, Bernard C.; Burns, Thomas P.

doi:10.1016/0304-3800(93)90037-s

Cited by 45 publications

(31 citation statements)

References 32 publications

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“…Conversely, if the available pool of organic material results from the slower decomposition of organic detritus by a complex microbial community, P and R would show a marked displacement. In this case, there would be a gradual increase in R with time, since microbial food webs (Azam et al 1983, Sherr & Sherr 1988) with many recycling flows, will tend to homogenise the distribution of energy among their components (Higashi et al 1993a,b, Nagata 2000. Thus, when the direct exudation of labile organic compounds by phytoplankton is small compared to the organic matter recycled from detritus by the microbial food web, a mismatch between the 2 metabolic processes may occur.…”

Section: Discussionmentioning

confidence: 99%

Decoupling of primary production and community respiration in the ocean: implications for regional carbon studies

Arı́stegui

Harrison²

2002

Aquat. Microb. Ecol.

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Primary production (P) and community respiration (R) were measured in vitro along 2 transects of a trans-oceanic section crossing the oligotrophic North Atlantic waters, and during a drifter experiment in the eutrophic waters of the Northwest Africa upwelling system. Our results indicate that the scales of variability of P and R are different, R being less variable than P in the 2 studies. In the first transect of the oceanic study, the mean P:R ratio was <1 (0.8), while in the second transect it was >1 (1.1), the difference being statistically significant. The cause was a significant increase in P in the second transect, which was decoupled from changes in chlorophyll a (chl a) or R. In upwelling waters, however, R was always significantly lower than P (P:R > 1), and enhancements in P were paralleled by increases in chl a but not in R. The close correlation between the P:R ratio and P (and the lack of correlation between P:R and R) supports the view that changes in P but not in R control the transition of the system from net heterotrophy to net autotrophy (in our study at P > 56 mmol C m -2 d -1 ). The observed decoupling between P and R at temporal scales of days to weeks, has strong implications for addressing metabolic balances from in vitro experiments carried out during limited field samplings. We conclude that unless the scales of variability are established for the 2 metabolic rates, and particularly for P, it will not be feasible to accurately establish regional metabolic balances at seasonal to annual scales.

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Section: Discussionmentioning

confidence: 99%

Decoupling of primary production and community respiration in the ocean: implications for regional carbon studies

Arı́stegui

Harrison²

2002

Aquat. Microb. Ecol.

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“…This may indicate that C transferred down from primary production in the surface layers may undergo several cycles in the DOC-microbial food chain before storage or loss from the system by deposition, current transport, or transformation into refractory DOC that cannot be mineralised on short time scales. Such a theoretical concept termed 'network virtual amplification' (Higashi et al 1993) has previously been suggested in relation to DOC-food web dynamics. It implies that no new energy is created, but that the amount of available energy is increased due to recycling.…”

Section: Carbon Cycling In the Reef And The Potential Role Of Coral-dmentioning

confidence: 99%

Microbial degradation of cold-water coral-derived organic matter: potential implication for organic C cycling in the water column above Tisler Reef

Wild¹,

Wehrmann²,

Mayr³

et al. 2009

Aquat. Biol.

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Cold-water corals release organic matter, in particular mucus, but its role in the ecological functioning of reef ecosystems is still poorly understood. The present study investigates the planktonic microbial degradation of mucus released by Lophelia pertusa colonies from Tisler Reef, Skagerrak. Results are compared to the degradation of dissolved and particulate organic substrates, including the carbohydrates glucose and starch, as well as gum xanthan and the cyanobacterium Spirulina spp. as the model organism for phytoplankton. Resulting microbial organic C degradation rates for the dissolved fraction of L. pertusa-derived mucus showed nearly linear progression over time and revealed similar degradation rates compared to glucose and starch. Degradation of the particulate mucus fraction, in contrast, displayed exponential progression and was much faster than degradation of the dissolved fraction. In addition, particulate mucus degradation showed a 4-fold increase compared to that of the added Spirulina spp. suspension. Mucus-associated microbial communities apparently play a key role in organic matter recycling, as degradation rates more than doubled in untreated compared to sterile coral-derived mucus over 3 d of incubation. Quantification of O 2 consumption in the water column above Tisler Reef showed significantly increased values in the direct vicinity of the reef. C-stable isotope signatures of suspended particulate organic matter close to Tisler were close to those of L. pertusa-derived mucus, and high dissolved organic carbon (DOC) concentrations were detected above Tisler Reef. These findings demonstrate the stimulating effect of cold-water coral reefs on microbial activity in the adjacent water column and may indicate some control over organic C cycling.

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“…This partitioning allows one to classify environ flow into what have been called different modes: mode 0) boundary input; 1) first passage flow received by an object from other objects in the system (i.e., not boundary flow), but also not cycled flow (in other words first time flow reaches an object); 2) cycled flow that returns to a compartment before leaving the system; 3) dissipative flow in that it has left the focal object not to return, but does not directly cross a system boundary (i.e., it flows to another within system object); and 4) boundary out (Higashi et al 1993). The modes have been used to understand better the general role of cycling and the flow contributions from each object to the other, which has had application in showing a complementarity of several of the holistic, thermodynamic-based ecological indicators (see Fath et al 2001).…”

Section: Theoretical Development Of Environ Analysismentioning

confidence: 99%

Analyzing Ecological Systems Using Network Analysis

Fath

2012

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Abstract. Network Environ Analysis, based on network theory, reveals the quantitative and qualitative relations between ecological objects interacting with each other in a system. The primary result from the method provides input and output "environs", which are internal partitions of the objects within system flows. In addition, application of Network Environ Analysis on empirical datasets and ecosystem models has revealed several important and non-intuitive results that have been identified and summarized in the literature as network environ properties. Network Environ Analysis requires data including the inter-compartmental flows, compartmental storages, and boundary input and output flows. Software is available to perform this analysis on the collected data. This article reviews the theoretical underpinning of the analysis and briefly introduces some the main properties such as indirect effects ratio, network homogenization, and network mutualism.

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Network trophic dynamics: the modes of energy utilization in ecosystems

Cited by 45 publications

References 32 publications

Decoupling of primary production and community respiration in the ocean: implications for regional carbon studies

Decoupling of primary production and community respiration in the ocean: implications for regional carbon studies

Microbial degradation of cold-water coral-derived organic matter: potential implication for organic C cycling in the water column above Tisler Reef

Analyzing Ecological Systems Using Network Analysis

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