Can animal habitat use patterns influence their vulnerability to extreme climate events? An estuarine sportfish case study

Abstract

Global climate forecasts predict changes in the frequency and intensity of extreme climate events (ECEs). The capacity for specific habitat patches within a landscape to modulate stressors from extreme climate events, and animal distribution throughout habitat matrices during events, could influence the degree of population level effects following the passage of ECEs. Here, we ask (i) does the intensity of stressors of an ECE vary across a landscape? And (ii) Do habitat use patterns of a mobile species influence their vulnerability to ECEs? Specifically, we measured how extreme cold spells might interact with temporal variability in habitat use to affect populations of a tropical, estuarine-dependent large-bodied fish Common Snook, within Everglades National Park estuaries (FL US). We examined temperature variation across the estuary during cold disturbances with different degrees of severity, including an extreme cold spell. Second, we quantified Snook distribution patterns when the passage of ECEs is most likely to occur from 2012 to 2016 using passive acoustic tracking. Our results revealed spatial heterogeneity in the intensity of temperature declines during cold disturbances, with some habitats being consistently 3-5°C colder than others. Surprisingly, Snook distributions during periods of greatest risk to experience an extreme cold event varied among years. During the winters of 2013-2014 and 2014-2015 a greater proportion of Snook occurred in the colder habitats, while the winters of 2012-2013 and 2015-2016 featured more Snook observed in the warmest habitats. This study shows that Snook habitat use patterns could influence vulnerability to extreme cold events, however, whether Snook habitat use increases or decreases their vulnerability to disturbance depends on the year, creating temporally dynamic vulnerability. Faunal global change research should address the spatially explicit nature of extreme climate events and animal habitat use patterns to identify potential mechanisms that may influence population effects following these disturbances.

Opportunities for behavioral rescue under rapid environmental change

“…Similarly, habitats containing thermal refugia—often defined as locations with lower amplitude temperature fluctuations through time (Logan et al, ; Scheffers, Edwards, et al, ; Scheffers, Evans, et al, )—will become increasingly spatially heterogeneous as increases because the difference between refugia and the rest of the habitat will correspondingly diverge. Likewise, extreme cold events were accompanied by decreased thermal spatial variability for fish in the Everglades National Park, limiting the movement behavior of Common Snook (Boucek, Heithaus, Santos, Stevens, & Rehage, ).…”

Poleward expansion of common snook Centropomus undecimalis in the northeastern Gulf of Mexico and future research needs

“…Therefore, we used air temperature data from NOAA gauge CDRF-1 instead of water temperature because the use of fixed measurements taken at a stationary location reduces variability and facilitates more consistent comparisons, and data from the site had fewer missing points than data from other sources. Finally, because the water in the larger sampling region is so shallow (<2m), water and air temperatures are likely to be similar [14,28]. We analyzed air temperature for instances of warm weather conditions by using linear regression to assess the relationship between the number of days in each year that temperature reached < 12˚C (the lower lethal limit for snook [22,24]).…”

“…During these cold events in our study, snook were captured near the mouth of the Suwannee River. Movement patterns of snook can affect their vulnerability to extreme cold events [28,53]. Snook in their historic range are known to migrate into rivers, creeks, and channels post-spawning to endure cold events [53].…”

More Than Just a Spawning Location: Examining Fine Scale Space Use of Two Estuarine Fish Species at a Spawning Aggregation Site

“…If less than two individuals were detected per day (i.e., male or female for species x), those days were excluded from analysis. To reduce effects of auto correlation, we grouped these daily proportions into 10 day bins, and used the average of those bins for analyses (See Walsh et al, 2013;Boucek et al, 2017). Wilcoxon sign rank tests were used to test whether proportional habitat use of Snook and Seatrout was different on seagrass habitats vs. spawning sites, as well as differences between males and females use of spawning and seagrass habitat.…”