TY - JOUR A1 - Kath, Nadja J. A1 - Boit, Alice A1 - Guill, Christian A1 - Gaedke, Ursula T1 - Accounting for activity respiration results in realistic trophic transfer efficiencies in allometric trophic network (ATN) models JF - Theoretical ecology N2 - Allometric trophic network (ATN) models offer high flexibility and scalability while minimizing the number of parameters and have been successfully applied to investigate complex food web dynamics and their influence on food web diversity and stability. However, the realism of ATN model energetics has never been assessed in detail, despite their critical influence on dynamic biomass and production patterns. Here, we compare the energetics of the currently established original ATN model, considering only biomass-dependent basal respiration, to an extended ATN model version, considering both basal and assimilation-dependent activity respiration. The latter is crucial in particular for unicellular and invertebrate organisms which dominate the metabolism of pelagic and soil food webs. Based on metabolic scaling laws, we show that the extended ATN version reflects the energy transfer through a chain of four trophic levels of unicellular and invertebrate organisms more realistically than the original ATN version. Depending on the strength of top-down control, the original ATN model yields trophic transfer efficiencies up to 71% at either the third or the fourth trophic level, which considerably exceeds any realistic values. In contrast, the extended ATN version yields realistic trophic transfer efficiencies 30% at all trophic levels, in accordance with both physiological considerations and empirical evidence from pelagic systems. Our results imply that accounting for activity respiration is essential for consistently implementing the metabolic theory of ecology in ATN models and for improving their quantitative predictions, which makes them more powerful tools for investigating the dynamics of complex natural communities. KW - Food web KW - Trophic transfer efficiency KW - Allometric trophic network model KW - Allometry KW - Energy transfer KW - Activity respiration Y1 - 2018 U6 - https://doi.org/10.1007/s12080-018-0378-z SN - 1874-1738 SN - 1874-1746 VL - 11 IS - 4 SP - 453 EP - 463 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Boit, Alice A1 - Spencer, Matthew T1 - Equivalence and dissimilarity of ecosystem states JF - Ecological modelling : international journal on ecological modelling and engineering and systems ecolog N2 - Measuring (dis)similarity between ecosystem states is a key theme in ecology. Much of community and ecosystem ecology is devoted to searching for patterns in ecosystem similarity from an external observer's viewpoint, using variables such as species abundances, measures of diversity and complexity. However, from the point of view of organisms in the ecosystem, proportional population growth rates are the only relevant aspect of ecosystem state, because natural selection acts on groups of organisms with different proportional population growth rates. We therefore argue that two ecosystem states are equivalent if and only if, for each species they contain, the proportional population growth rate does not differ between the states. Based on this result, we develop species-level and aggregated summary measures of ecosystem state and discuss their ecological meaning. We illustrate our approach using a long-term dataset on the plankton community from the Central European Lake Constance. We show that the first three principal components of proportional population growth rates describe most of the variation in ecosystem state in Lake Constance. We strongly recommend using proportional population growth rates and the derived equivalence classes for comparative ecosystem studies. This opens up new perspectives on important existing topics such as alternative stable ecosystem states, community assembly, and the processes generating regularities in ecosystems. KW - Hutchinson niche KW - Ecosystem dynamics KW - Ecosystem dissimilarity KW - Proportional population growth rate KW - Per capita growth rate Y1 - 2019 U6 - https://doi.org/10.1016/j.ecolmodel.2019.01.009 SN - 0304-3800 SN - 1872-7026 VL - 396 SP - 12 EP - 22 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Mirhaj, M. A1 - Boit, Alice A1 - Razzak, M. A. A1 - Wahab, M. A. T1 - Yield performance comparison between cultures of rice cum prawn (Macrobrachium rosenbergii) and rice cum fish (Cyprinus carpio, Oreochromis niloticus) in North-Eastern Bangladesh JF - Aquaculture : an international journal devoted to research on the exploration and improvement of all aquatic food resources, both floristic and faunistic, from freshwater, brackish and marine environment, related directly or indirectly to human consumption N2 - Integrated and concurrent cultures in rice fields are a promising approach to sustainable farming as the demand for aquacultural and agricultural products continues to grow while land and water resources become increasingly scarce. Prawn farming mainly takes place in coastal regions in improved extensive to semi-intensive aquacultures but a trend to shift the industry to inland regions has been noticed. This inland study in Northern Bangladesh used different input regimes such as fertilizer and additional feed to compare the performance of prawn and fish in flooded paddy fields in regard to water quality measurements. Maximal net yields and body weight gain with minimized negative impact on water quality were found when initial body weights of prawn were optimized. Regarding yield factors in reference to the reduction of costs due to the avoidance of expensive fertilizer/feed and effort, prawn performed better than integrated fish cultures considering a higher market value of prawn with net yields of up to 97 +/- 55 kg ha(-1) for unfed and 151 +/- 61 kg ha(-1) for fed treatments. Rice yields of up to 4.7 +/- 0.1 t ha(-1) for unfed and 4.4 +/- 0.1 t ha(-1) were achieved for fed treatments. The findings suggest that for small scale farmers, prawn cum rice cultures are an economically profitable and comparatively easily manageable alternative to rice cum fish cultures. KW - Rice cum prawn culture KW - Macrobrachium rosenbergii KW - Sustainable aquaculture KW - Polyculture Y1 - 2013 U6 - https://doi.org/10.1016/j.aquaculture.2013.01.038 SN - 0044-8486 VL - 392 IS - 5 SP - 26 EP - 33 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kefi, Sonia A1 - Berlow, Eric L. A1 - Wieters, Evie A. A1 - Navarrete, Sergio A. A1 - Petchey, Owen L. A1 - Wood, Spencer A. A1 - Boit, Alice A1 - Joppa, Lucas N. A1 - Lafferty, Kevin D. A1 - Williams, Richard J. A1 - Martinez, Neo D. A1 - Menge, Bruce A. A1 - Blanchette, Carol A. A1 - Iles, Alison C. A1 - Brose, Ulrich T1 - More than a meal ... integrating non-feeding interactions into food webs JF - Ecology letters N2 - Organisms eating each other are only one of many types of well documented and important interactions among species. Other such types include habitat modification, predator interference and facilitation. However, ecological network research has been typically limited to either pure food webs or to networks of only a few (<3) interaction types. The great diversity of non-trophic interactions observed in nature has been poorly addressed by ecologists and largely excluded from network theory. Herein, we propose a conceptual framework that organises this diversity into three main functional classes defined by how they modify specific parameters in a dynamic food web model. This approach provides a path forward for incorporating non-trophic interactions in traditional food web models and offers a new perspective on tackling ecological complexity that should stimulate both theoretical and empirical approaches to understanding the patterns and dynamics of diverse species interactions in nature. KW - Ecological network KW - ecosystem engineering KW - facilitation KW - food web KW - interaction modification KW - non-trophic interactions KW - trophic interactions Y1 - 2012 U6 - https://doi.org/10.1111/j.1461-0248.2011.01732.x SN - 1461-023X VL - 15 IS - 4 SP - 291 EP - 300 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Boit, Alice A1 - Gaedke, Ursula T1 - Benchmarking successional progress in a quantitative food web JF - PLoS one N2 - Central to ecology and ecosystem management, succession theory aims to mechanistically explain and predict the assembly and development of ecological communities. Yet processes at lower hierarchical levels, e. g. at the species and functional group level, are rarely mechanistically linked to the under-investigated system-level processes which drive changes in ecosystem properties and functioning and are comparable across ecosystems. As a model system for secondary succession, seasonal plankton succession during the growing season is readily observable and largely driven autogenically. We used a long-term dataset from large, deep Lake Constance comprising biomasses, auto-and heterotrophic production, food quality, functional diversity, and mass-balanced food webs of the energy and nutrient flows between functional guilds of plankton and partly fish. Extracting population-and system-level indices from this dataset, we tested current hypotheses about the directionality of successional progress which are rooted in ecosystem theory, the metabolic theory of ecology, quantitative food web theory, thermodynamics, and information theory. Our results indicate that successional progress in Lake Constance is quantifiable, passing through predictable stages. Mean body mass, functional diversity, predator-prey weight ratios, trophic positions, system residence times of carbon and nutrients, and the complexity of the energy flow patterns increased during succession. In contrast, both the mass-specific metabolic activity and the system export decreased, while the succession rate exhibited a bimodal pattern. The weighted connectance introduced here represents a suitable index for assessing the evenness and interconnectedness of energy flows during succession. Diverging from earlier predictions, ascendency and eco-exergy did not increase during succession. Linking aspects of functional diversity to metabolic theory and food web complexity, we reconcile previously disjoint bodies of ecological theory to form a complete picture of successional progress within a pelagic food web. This comprehensive synthesis may be used as a benchmark for quantifying successional progress in other ecosystems. Y1 - 2014 U6 - https://doi.org/10.1371/journal.pone.0090404 SN - 1932-6203 VL - 9 IS - 2 PB - PLoS CY - San Fransisco ER - TY - JOUR A1 - Boit, Alice A1 - Martinez, Neo D. A1 - Williams, Richard J. A1 - Gaedke, Ursula T1 - Mechanistic theory and modelling of complex food-web dynamics in Lake Constance JF - Ecology letters N2 - Mechanistic understanding of consumer-resource dynamics is critical to predicting the effects of global change on ecosystem structure, function and services. Such understanding is severely limited by mechanistic models inability to reproduce the dynamics of multiple populations interacting in the field. We surpass this limitation here by extending general consumer-resource network theory to the complex dynamics of a specific ecosystem comprised by the seasonal biomass and production patterns in a pelagic food web of a large, well-studied lake. We parameterised our allometric trophic network model of 24 guilds and 107 feeding relationships using the lakes food web structure, initial spring biomasses and body-masses. Adding activity respiration, the detrital loop, minimal abiotic forcing, prey resistance and several empirically observed rates substantially increased the model's fit to the observed seasonal dynamics and the size-abundance distribution. This process illuminates a promising approach towards improving food-web theory and dynamic models of specific habitats. KW - Allometric Trophic Network model KW - community ecology KW - food web KW - multi-trophic dynamics KW - seasonal plankton succession Y1 - 2012 U6 - https://doi.org/10.1111/j.1461-0248.2012.01777.x SN - 1461-023X VL - 15 IS - 6 SP - 594 EP - 602 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Sakschewski, Boris A1 - von Bloh, Werner A1 - Boit, Alice A1 - Poorter, Lourens A1 - Pe~na-Claros, Marielos A1 - Heinke, Jens A1 - Joshi, Jasmin Radha A1 - Thonicke, Kirsten T1 - Resilience of Amazon forests emerges from plant trait diversity JF - Nature climate change Y1 - 2016 U6 - https://doi.org/10.1038/NCLIMATE3109 SN - 1758-678X SN - 1758-6798 VL - 6 SP - 1032 EP - + PB - Nature Publ. Group CY - London ER -