Table 2.
. Indices developed to summarize the impacts of urbanization and climate change on fish assemblages for the FIF model*
| Indices | Explanation | Environmental factors contributing | Species characteristics contributing |
|---|---|---|---|
| I SDA index of spawning day availability (% days during the typical spawning period for each species when predicted water temperature falls within the spawning temperature range) | Effect of warming on days available for spawning | Daily temperature | Spawning times |
| Spawning temperatures | |||
| I SS index of spawning substrate (% spawning days impacted by siltation†) | Effect of siltation on spawning | Discharge Siltation | Spawning care |
| Spawning mode | |||
| Spawning months | |||
| I SS index of juvenile growth (no of days required to grow to maturity given predicted temperature and likelihood of eggs/young being washed out by high flows‡) | Effect of warming and washout on development time for juveniles | Daily temperature | Spawning times |
| Summer temperature surges | Temperature group | ||
| Time to 40 mm length | |||
| I AG index of adult growth (% days on which ‘positive growth’ was possible§) | Days during which positive growth can occur for adults | Daily temperature | Temperature group |
| Food availability | Adult food preferences | ||
| Summer temperature surges |
*full details and assumption justifications in Supporting Information, Appendix S4.
Siltation impedes flow of interstitial oxygen and depresses hatching rates of eggs (Soulsby et al. 2001; Lapointe et al. 2004). Species that clean and aerate their nests or position their eggs to avoid siltation were assumed less vulnerable (Johnston 1999). The index also reflected the availability of appropriately sized spawning substrate for species that build nests or redds.
We assumed that juveniles had high growth rates only in the middle half of the ‘good growth’ range for adults (Rombough 1997).
Positive growth was possible when water temperature was within ‘good growth’ range for the species’ temperature guild and at least one of the food types eaten by the species (detritus, algae, invertebrates, and/or small fishes) was above a non‐limiting threshold.