Ecospace inherits settings, parameters, and data from Ecosim (which in turn has inherited some parameter values from Ecopath), and requires expression of additional parameters that explain how the food web and fisheries utilize space. Butt Ecospace cannot use all Ecosim values, but only parameters that either do not have an explicit spatial component (such as vulnerability settings, mediation effects and environmental response functions) or that Ecospace can spatialize (such as total functional group biomasses and fishing effort intensity). Driver and reference time series in Ecosim do not transfer to Ecospace as these time series lack a spatial component explaining how their impacts are distributed, and Ecospace does not have sufficient basic structure to spatialize these drivers. Instead, Ecospace requires the user to re-express these drivers and reference time series as explicit maps that have both spatial distribution and magnitude patterns.

Biomass

The total biomass per functional group is used from the base Ecopath model at initialization. During the initialization of a run, Ecospace will distribute the functional group biomasses based on the HFC model settings. While the model runs, dynamic food-web processes and other effects will take place and influence species distributions^[1].

Biomass Forcing Time Series

Ecosim biomass forcing time series inputs can be used to force the biomass of Ecospace. When this feature is enabled the spatially averaged biomass predicted by Ecospace will be equal to the Ecosim forced biomass from the forcing time series at the current time step. The spatial distribution of biomass will still be predicted by the Ecospace dispersal model.

How it Works

During the initialization of Ecospace the Capacity Model sets the capacity of each cell based on either the Foraging Response or the Habitat Base Foraging settings. Then the Ecopath biomass is spatially distributed across the map using the cell capacity and or the migration preference of each cell as a weighting factor.  At the end of the initialization the spatially average biomass of Ecospace will equal the baseline Ecopath biomass.

When the Ecosim biomass forcing is enabled the biomass from the time series will be distributed across the map using the current biomass distribution pattern. This maintains the spatial distributions predicted by Ecospace but overrides the biomass in a given cell.

This takes the form,

[latex]B_{ijk}=Bf_{kt}\frac{B_{ijk}}{\bar B_k} \tag{1}\label{1}[/latex]

where B_ijk is the biomass in row i column j for group k, Bf_kt is the time series forced biomass for group k at time step t, [latex]\bar B_k[/latex] is the mean Ecospace biomass of group k.

How to Use It

Load time series data containing biomass forcing into Ecopath via the Ecosim Time series interface. Only time series data define as Biomass forcing (-1) will be used to force the Ecospace biomass. This makes the forcing data available to Ecospace but by default it will not be enabled. To enable it check the Use Ecosim biomass forcing check box on the Ecospace parameters interface, under the Time Series heading. If no forcing data is loaded this check box will be grayed out. You can turn individual forcing time series on or off via the Ecosim Time series interface.

Fishing Effort

The magnitude of fishing effort is inherited from Ecosim and is spatially distributed with the dedicated Ecospace gravity model^[2]. Effort distributions are thus an Ecospace output, as are fishing mortality estimates (see 1.4.6). Note that Ecospace does NOT use Ecosim fishing mortalities, as it cannot predict where these mortalities might occur.

Vulnerabilities

Ecospace will use the vulnerability settings of Ecosim. Low vulnerabilities for a given predator imply that it is close to its carrying capacity, hence limiting how much the predator’s consumption can increase if it should become more abundant. Note that vulnerabilities fitted in Ecosim assume spatial homogeneity, which becomes a less appropriate assumption for Ecospace maps that strongly partition predator and prey. In Ecospace, a species can be confined in small core areas depending on their habitat preferences (e.g., defined depth ranges) and area occupancy can change dynamically in response to predator and prey dynamics in which, when there is a match of distributions of either their predators or the fisheries, the species can have a higher encounter rate and mortality. There is currently no option in the software to perform the vulnerability parameter fitting, as in Ecosim, using Ecospace dynamics.

Mediation Effects

In Ecosim, inter-species mediation effects are applied to the modelled domain as a whole^{[3] [4]}. In Ecospace, these effects play out in each individual Ecospace cell.

Environmental Responses

Both Ecosim and Ecospace offer the ability to express functional group sensitivities to environmental conditions. The sensitivities are defined via environmental response functions ^[5], definitions that are shared between Ecosim and Ecospace.

In Ecosim, environmental conditions are expressed as time varying forcing functions that represent environmental variables for the modeled area as a whole. In Ecospace, environmental conditions are expressed as maps that indicate both magnitude and distribution of an environmental variable, and these maps can be made time varying via the spatial temporal data framework ^[6].

There is no satisfactory way to internally convert non-spatial environmental driver forcing functions in Ecosim to their spatially explicit counterpart in Ecospace. There is also no satisfactory way to ensure that the same environmental conditions are adequately represented in both Ecosim and Ecospace. Therefore, the EwE software is not able to transfer applied environmental drivers from Ecosim to Ecospace. Users therefore must configure environmental driver data in Ecosim and Ecospace separately.

Adaption

The chapter is in part adapted, with permission,  from: De Mutsert K, Marta Coll, Jeroen Steenbeek, Cameron Ainsworth, Joe Buszowski, David Chagaris, Villy Christensen, Sheila J.J. Heymans, Kristy A. Lewis, Simone Libralato, Greig Oldford, Chiara Piroddi, Giovanni Romagnoni, Natalia Serpetti, Michael Spence, Carl Walters. 2023. Advances in spatial-temporal coastal and marine ecosystem modeling using Ecopath with Ecosim and Ecospace. Treatise on Estuarine and Coastal Science, 2nd Edition. Elsevier.