Top-down, bottom-up or middle-out? Avoiding extraneous detail and over-generality in marine ecosystem models

Allen, J. Icarus; Fulton, Elizabeth A.

doi:10.1016/j.pocean.2009.09.016

Cited by 27 publications

(14 citation statements)

References 28 publications

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“…We examined top‐down and bottom‐up cascade effects in a marine food web model of intermediate complexity (Allen & Fulton ; Steele et al . ), which represents the fluxes of nutrient (nitrogen) through the North Sea ecosystem from dissolved inorganic to birds and mammals, and regeneration through excretion and mineralisation of detritus (Heath ; see Appendix S2 in Supporting Information).…”

Section: Marine Food Web Simulationsmentioning

confidence: 99%

Understanding patterns and processes in models of trophic cascades

2013

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Climate fluctuations and human exploitation are causing global changes in nutrient enrichment of terrestrial and aquatic ecosystems and declining abundances of apex predators. The resulting trophic cascades have had profound effects on food webs, leading to significant economic and societal consequences. However, the strength of cascades–that is the extent to which a disturbance is diminished as it propagates through a food web–varies widely between ecosystems, and there is no formal theory as to why this should be so. Some food chain models reproduce cascade effects seen in nature, but to what extent is this dependent on their formulation? We show that inclusion of processes represented mathematically as density-dependent regulation of either consumer uptake or mortality rates is necessary for the generation of realistic ‘top-down’ cascades in simple food chain models. Realistically modelled ‘bottom-up’ cascades, caused by changing nutrient input, are also dependent on the inclusion of density dependence, but especially on mortality regulation as a caricature of, e.g. disease and parasite dynamics or intraguild predation. We show that our conclusions, based on simple food chains, transfer to a more complex marine food web model in which cascades are induced by varying river nutrient inputs or fish harvesting rates.

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Section: Marine Food Web Simulationsmentioning

confidence: 99%

Understanding patterns and processes in models of trophic cascades

2013

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“…This includes the development of methods for linking together different types of models such as biogeochemical, population and food web models [97]. A key aspect of this work is to link to human activities, focusing mainly on fisheries activities, and a range of models of food webs and fisheries are being linked to biogeochemical and physical models [98,99]. Some key features of ocean ecosystem models are that they frequently operate at large scales (sometimes a global scale) and that they integrate the physical environment into models more extensively than is typical for terrestrial models.…”

Section: Systems Ecology Is Already Being Practisedmentioning

confidence: 99%

“…Developing models that resolve the appropriate physical, chemical, biological and social processes at different scales presents a major challenge [99,118–121], but scaling from individual behaviours to changes in population sizes at a regional scale is being attempted [100,122]. …”

Section: What Are the Challenges?mentioning

confidence: 99%

Predictive systems ecology

et al. 2013

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Human societies, and their well-being, depend to a significant extent on the state of the ecosystems that surround them. These ecosystems are changing rapidly usually in response to anthropogenic changes in the environment. To determine the likely impact of environmental change on ecosystems and the best ways to manage them, it would be desirable to be able to predict their future states. We present a proposal to develop the paradigm of predictive systems ecology, explicitly to understand and predict the properties and behaviour of ecological systems. We discuss the necessary and desirable features of predictive systems ecology models. There are places where predictive systems ecology is already being practised and we summarize a range of terrestrial and marine examples. Significant challenges remain but we suggest that ecology would benefit both as a scientific discipline and increase its impact in society if it were to embrace the need to become more predictive.

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“…Confusion concerning the assignment to these three terms seems to be typical and might be related to the various contextual and conceptual frameworks used by the different authors. Within the marine-focused literature many studies consider only anthropogenic factors as drivers or driving forces (Maxim et al, 2009) related to the certain socioeconomic activities (Patricio et al, 2014a), while others refer the term 'driver' to both natural and anthropogenic factors (Allen and Fulton, 2010;Harwell et al, 2010;MA, 2005).…”

Section: 'Driver'mentioning

confidence: 99%

Drivers and pressures – Untangling the terms commonly used in marine science and policy

Oesterwind

Rau

Zaiko

2016

Journal of Environmental Management

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In the marine sciences an increasing number of studies on environmental changes, their causes, and environmental assessments emerged in recent years. Often authors use non-uniform and inconsistent definitions of key terms like driver, threats, pressures etc. Although all of these studies clearly define causal dependencies between the interacting socio-economic and environmental systems in an understandable way, still an overall imprecise wording could induce misunderstanding at higher policy levels when it comes to integrated ecosystems assessments. Therefore we recommend using unified definitions for a better communication between science and management within national, regional and international environmental policies, for example the European Marine Strategy Framework Directive (MSFD). With this article we provide definitions compatible with the driver-pressure-state-impact-response (DPSIR) approach. Although most examples are MSFD related and thus have a marine focus the definitions are intended to be equally applicable for other systems and are usable world-wide. We suggest sticking to these definitions for an easy and simplified knowledge transfer from science to management, since DPSIR model is already accepted as a helpful tool for structuring and communicating ecosystem analyses.

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Top-down, bottom-up or middle-out? Avoiding extraneous detail and over-generality in marine ecosystem models

Cited by 27 publications

References 28 publications

Understanding patterns and processes in models of trophic cascades

Understanding patterns and processes in models of trophic cascades

Predictive systems ecology

Drivers and pressures – Untangling the terms commonly used in marine science and policy

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