Global Seamounts Project
Modeling Seamount Ecosystems
Ursula Scharler, PhD
University of KwaZulu-Natal, Durban, South Africa
The modelling component of the Global Seamounts Project (GSP) aims to characterise system functioning of seamounts. As such, the models are used to integrate information generated from the field campaigns and other physical and biogeochemical models. We aim to use different, existing, marine ecosystem modelling frameworks, and generate new frameworks where appropriate.
Different modelling frameworks prominent in the literature use a somewhat different focus to increase understanding of ecosystem structure, function, and behaviour. An advantage of using different approaches is the increased representation of model uncertainty, which is a vital component of the modelling procedure as it informs on accurateness and precision of modelling outcomes.
All modelling frameworks touch on the description and function of ecosystems, and concentrate on the species, community, and systems level. This is accomplished by focussing on the interaction among biota and between biota and the environment. The input data for modelling will be generated by the physical, biogeochemical, and biological studies on selected seamounts, and a close collaboration between the modelling and the various other working groups will ensure that essential data are collected.
The modelling frameworks can be divided into two very different approaches – one type of approach that aims to describe the dynamics of the ecosystem, identifying its drivers and building scenarios of changes imposed on the dynamic model to examine effects on certain biota (e.g. changes in biomass, effects of fisheries, etc.). The second identifies attributes of system function from multiple networks of interactions, such as resilience, persistence, or stability of the system. The two approaches can be combined to provide an integrated picture of system function and behaviour.
For the GSP, we propose initially, but not exclusively, several modelling frameworks shown in Figure 1.
Development of an Integrated Seamount Ecosystem Model (ISEM)
The various modelling frameworks are built on similar foundations (physical processes, bioenergetics of biotic components, some include socioeconomics) but focus on different outcomes. For instance, at present OSMOSE, ATLANTIS and EwE are mainly geared towards fisheries applications, whereas OSIRIS and Systems Analysis focus on species, community and ecosystem level interactions, and the functioning of ecosystems in themselves (see Figure 2).
A fundamental question in modelling is the evaluation of the accuracy and precision of model results, and the assessment of the accompanying, and unavoidable, uncertainty. Through different modelling frameworks we aim for a better assessment of both ecosystem attributes and behaviour, and that of model uncertainty.
As there are no modelling frameworks specific to seamount ecosystems, an important outcome of the GSP programme will be the incorporation of attributes from multiple existing modelling frameworks into a new Integrated Seamount Ecosystem Model (ISEM). The development of an ISEM that combines contributions from multiple modelling frameworks, together with geospatially comprehensive, multidisciplinary datasets intercalibrated from across an array of seamount sites, is intended to provide an additional new approach to exploring functional ecosystem dynamics for seamounts.
It is hoped that an ISEM model as proposed by this project will contribute to a significantly improved understanding of potential future ecosystem scenarios for seamounts driven by climate change and human impacts.
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