I would like to use a model to assess the cumulative risk of aquaculture, marine traffic, and anoxia/hypoxia zones on small cetaceans in a marine reserve. I am an undergraduate student, and I am unsure if it is possible to use these models for my intended purpose. Additionally, I am uncertain about which model to use: should I perform a risk assessment for the species (in this case, dolphins) or for the habitat (marine reserve)?
I have read the InVEST manual, and it appears that their risk assessments mainly focus on sessile species. Consequently, I am unsure if I can adapt it for use with dolphins.
I have spatial information on the following:
The distribution of small cetaceans in raster format.
Aquaculture concessions represented as polygons.
High-density areas of aquaculture-related marine traffic modeled in raster format.
Anoxia/hypoxia zones as points.
The marine reserve as a polygon.
I would appreciate an informative response as I am new to this field and have limited comprehension of these concepts. If you have any literature or research examples related to similar investigations, I would greatly appreciate it.
I would also like some guidance on the InVEST model interface, such as:
Which distance metric is more favorable for risk assessment, Euclidean or multiplicative? How do I determine which one to choose?
Regarding the decay equation, what does it mean for it to be linear or exponential, and which would be the best to use?
In the Habitat Stressor Table, should I include both my cetacean species and threats? Additionally, in the “path” statement, should I specify the raster file path on my computer?
I apologize for the numerous questions, but as I mentioned earlier, I am new to this subject and eager to learn more.
I will do my best to answer your questions here, but since I’m not a habitat/species risk domain specialist, I will also happily defer to others (@swolny@jesseG@Jess_Silver@jade , others?).
My understanding of the InVEST HRA model is that although the model is called Habitat risk assessment, it can also be used to model risk to species. Anecdotally, others have modeled risk to cetaceans as well, though I do not have a citation to point to. The HRA model allows you to specify multiple different habitats and stressors, so you could include a layer each for dolphins and a marine reserve (or even different habitats within a marine reserve).
There is a Note section in the InVEST User’s Guide chapter for HRA Habitat Risk Assessment — InVEST® documentation that discusses tradeoffs between the risk calculations. If you have further questions, please let us know!
The decay equation allows you to specify how the effects of the stressor are felt over the maximum distance of the threat’s effect. Does the influence decay linearly? Or is the stressor most acutely felt up close, and much, much less as you get farther away (exponential decay)? What would be best to use depends on your input layers and the assumptions you are making.
Yes. HRA will model the threats provided to the species provided in the habitat stressor table.
Yes, you would provide the path to a raster or vector file defining presence of the habitat or stressor. Example data are provided (they can be downloaded in the InVEST workbench or from this URL), for your reference, and they are described in the User’s Guide chapter for HRA.