Reconstructing historical marine ecosystems using food web models: Northern British Columbia from Pre-European contact to present

Ainsworth, Cameron H.; Pitcher, Tony J.; Heymans, Johanna J.; Vasconcellos, Marcelo

doi:10.1016/j.ecolmodel.2008.05.005

Cited by 42 publications

(44 citation statements)

References 48 publications

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“…Their parameters were derived mainly from a previous, more spatially extensive but ecologically simpler model built for northern British Columbia by Ainsworth et al . (). All modifications to this model are detailed in Supplementary Information (S3).…”

Section: Methodsmentioning

confidence: 99%

Predicting the effects of whale population recovery on Northeast Pacific food webs and fisheries: an ecosystem modelling approach

Surma

Pitcher

2015

Fisheries Oceanography

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The recovery of whale populations from historical depletion may have the potential to noticeably affect Northeast Pacific ecosystems and fisheries. Surplus production models based on whaling catch records were used to reconstruct the historical abundances of five large whale species in the waters surrounding Haida Gwaii, British Columbia. The results suggest that the local abundances of all five species were vastly higher before the onset of modern whaling. A comparison of ecosystem models representing the states of the local marine food web before and after full whale recovery indicates that abundant whales could consume large proportions of the annual production of their principal prey, ranging up to 87% for Pacific herring (Clupea pallasii) and 72% for piscivorous rockfish (Sebastes spp.). Dynamic modelling of the food web effects of whale recovery, including simulations of simultaneous top‐down and bottom‐up forcing and a Monte Carlo sensitivity analysis, revealed noticeable (∼6–12%) top‐down effects on Pacific herring biomass owing to increased predation by humpback and fin whales. However, these effects cannot explain the magnitude of recent declines in local herring biomass. The dynamic modelling results also suggest that top‐down effects of whale recovery could result in reduced biomasses of large rockfish as a result of predation by sperm whales, as well as potential cascading effects on many demersal fish groups. These findings have numerous practical implications for ecosystem‐based fisheries management and whale conservation strategies in Northeast Pacific waters.

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Section: Methodsmentioning

confidence: 99%

Predicting the effects of whale population recovery on Northeast Pacific food webs and fisheries: an ecosystem modelling approach

Surma

Pitcher

2015

Fisheries Oceanography

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“…The functional groups, linkages, mechanisms, and parameters that make up an ecosystem model are generally intended to represent a particular system state, which has arisen based on many shortand long-term drivers and factors. The state of a given ecosystem changes over time, sometimes considerably, and that is especially true of systems that are exploited by humans (e.g., Ainsworth et al 2008a). The mediating relationships explored here may very well have developed across large spatial and temporal scales within that dynamic system.…”

Section: Discussionmentioning

confidence: 99%

Mediation functions in Ecopath with Ecosim: handle with care

HarveyChris

2014

Can. J. Fish. Aquat. Sci.

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Ecosystem models are important tools for addressing complex issues such as the role of habitat in marine resource management. The Ecopath with Ecosim (EwE) software can represent several ecological processes via mediation functions, where the abundance of one group influences trophic interactions between two other groups. I ran a series of temporal simulations in EwE, in which eelgrass (Zostera marina) was refuge habitat for juvenile Pacific salmon (Oncorhynchus spp.), and the abundance of eelgrass mediated (reduced) the vulnerability of juvenile salmon to their predators. I compared the effects of eelgrass on salmon biomass across three shapes of mediation curve (linear, hyperbolic, sigmoid) and six different initial states along each curve. Salmon responded strongest to sigmoid mediation and least to hyperbolic mediation. Salmon responses were sensitive to initial conditions, particularly along sigmoid curves. As the lower limit of the mediation curve (M min ) approached 0, model results became nonintuitive, particularly for sigmoid curves. Because these functions are difficult to quantify or scale from empirical or experimental studies, modelers must carefully account for uncertainty when using mediation relationships in EwE. Hyperbolic mediation curves may be the most conservative when empirical or theoretical knowledge is unavailable. Résumé :Les modèles d'écosystèmes sont d'importants outils pour examiner des questions complexes telles que le rôle de l'habitat dans la gestion des ressources marines. Le logiciel Ecopath with Ecosim (EwE) peut représenter plusieurs processus écologiques par des fonctions de médiation selon lesquelles l'abondance d'un groupe influence les interactions trophiques de deux autres groupes. J'ai réalisé une série de simulations avec EwE dans lesquelles la zostère marine (Zostera marina) constituait un habitat refuge pour des saumons du Pacifique (Oncorhynchus spp.) juvéniles et l'abondance de la zostère influençait (réduisait) la vulnérabilité des jeunes saumons à leurs prédateurs. J'ai comparé les effets de la zostère sur la biomasse de saumons pour trois formes de courbes de médiation (linéaire, hyperbolique et sigmoïde) et six états initiaux distincts le long de chaque courbe. Les saumons réagissaient le plus fortement à la médiation sigmoïde et le moins fortement à la médiation hyperbolique. Les réactions des saumons étaient sensibles aux conditions initiales, particulièrement le long des courbes sigmoïdes. Quand la limite inféri-eure de la courbe de médiation (M min ) tendait vers 0, les résultats des modèles devenaient non intuitifs, particulièrement pour les courbes sigmoïdes. Puisque ces fonctions sont difficiles à quantifier ou à mettre à partir d'études empiriques ou expérimen-tales, les modélisateurs doivent prendre soin de bien rendre compte de l'incertitude quand ils utilisent des relations de médiation dans EwE. Les courbes de médiation hyperboliques pourraient constituer l'option la plus prudente dans les cas où de l'information empirique ou théorique n'est pas dispo...

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“…Given our inability to conduct controlled experiments at the scale of LMEs, and in the absence of a comprehensive theory that could predict expected interactions of all the components within LMEs and the evolution of these systems through time, modeling of such systems appears to be a necessary tool to link our understanding of organism-level interactions with the ecosystems dynamics that these interactions produce. Such models can be used to provide the science essential for developing an ecosystem-based management (Toft & Mangel, 1991;Pauly & Christensen, 1995;Ainsworth et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Evaluating ecosystem structure and functioning of the East China Sea Shelf ecosystem, China

Chen

Olson

et al. 2009

Hydrobiologia

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As China's second-largest large marine ecosystem, the East China Sea Shelf has suffered from overfishing, eutrophication, and physical disturbance over the last several decades. A trophic mass-balance model of this ecosystem was developed in order to characterize the structure and functioning of its food web, to identify its keystone species, and to quantify the ecological impacts of fishing that it sustained during the early 2000s. Using a multivariate statistical analysis, we identified 38 functional groups for the trophic model, including fish and invertebrate groups targeted and not targeted by fisheries. Pelagic sharks and rays were identified as the keystone species in the ecosystem. Strong benthic-pelagic coupling was indicated in this ecosystem. In particular, this study highlighted the interdependent relationships that exist among plankton, benthic invertebrates, and detritus. Recent fishing activities were characterized by high exploitation rates for various commercially targeted and non-targeted species, leading to the removal of much of the ecosystem's fishable production. Overall, our findings give a preliminary explanation of the current problems of eutrophication and fishery depletion and other changes in the East China Sea Shelf, and highlight the need for developing ecosystem-based fisheries management.

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Reconstructing historical marine ecosystems using food web models: Northern British Columbia from Pre-European contact to present

Cited by 42 publications

References 48 publications

Predicting the effects of whale population recovery on Northeast Pacific food webs and fisheries: an ecosystem modelling approach

Predicting the effects of whale population recovery on Northeast Pacific food webs and fisheries: an ecosystem modelling approach

Mediation functions in Ecopath with Ecosim: handle with care

Evaluating ecosystem structure and functioning of the East China Sea Shelf ecosystem, China

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