Effects of life‐history traits on stream fish abundances across spatial scales

Abstract

Identifying cross‐scale patterns of ecological processes is imperative, especially in hierarchically structured riverine ecosystems. The role of abiotic factors in determining cross‐scale spatial structure of stream fish populations and communities is well studied, but less is known about how species traits drive cross‐scale patterns. We investigated the role of species traits for explaining autocorrelation of stream fish abundance at spatial scales ranging from local stream reaches to major basins. We calculated intraclass correlation coefficients (ICCs) representing abundance autocorrelation within species (N = 47) at each of five spatial scales. A hierarchical Bayesian regression then modelled ICCs against spatial scale with the resulting regression coefficients modelled as functions of species traits. Finally, we ordinated the scale‐by‐species ICC matrix to calculate an overall metric describing species whose abundances were autocorrelated along a gradient of large to small scales, and modelled this metric as a function of species traits. Abundances of most species were autocorrelated at smaller spatial scales. Maximum fecundity had a significant positive relationship with abundance patterns across spatial scales. Species habitat affinities and body forms were significantly associated with overall abundance patterns across spatial scales: populations of upland/lotic‐affiliated species adapted to streams with high flow correlated at small (≤10 km2) spatial scales. Lowland/lacustrine species with laterally compressed bodies showed little correlation across scales. The appropriate spatial scale for modelling abundance is determined not only by exogenous (e.g. environmental) factors, but also endogenous factors, like traits. Careful consideration of traits and life history will aid researchers in designing more effective and efficient surveys and analyses.

Spatial asynchrony and cross‐scale climate interactions in populations of a coldwater stream fish

“…Likewise, the identification of asynchronous outliers depends on the geographic extent and distribution of sampling sites. Still, our estimated spatial scales of trout synchrony are comparable to those of other freshwater species (Copeland & Meyer, 2011;Myers et al, 1997;Tedesco et al, 2004), and our average ICC values (i.e., magnitude of synchrony) were similar to those reported for other freshwater fish species (e.g., Michaletz & Siepker, 2013;Midway & Peoples, 2019) and considerably lower than those for terrestrial species (e.g., Canu et al, 2015;Grosbois et al, 2009;Lahoz-Monfort et al, 2011). Weaker synchrony of freshwater populations versus terrestrial populations may be due to stronger cross-scale interactions arising from fine-scale aquatic habitat heterogeneity (Benda et al, 2004;McCluney et al, 2014) and physical isolation of habitats by watershed boundaries (e.g., headwater streams) that prevent movement of aquatic organisms (Liebhold et al, 2004;Ranta et al, 1995).…”

Effects of environment and metacommunity delineation on multiple dimensions of stream fish beta diversity

“…These streams are also connected more closely to large mainstem rivers and reservoirs and share more species among watersheds due to historical sea level change (Marion et al, 2015;Miller et al, 2020;Denison et al, 2021b). Moreover, the species inhabiting the lowland streams tend to have more dispersal-associated traits and have populations that respond more to connectivity than local-scale abiotic factors (Midway and Peoples, 2019). Humans also historically connected lowland watersheds during the canal boom of the 1790s-1830s that saw over 3,200 km of cross-watershed canal construction, as well as widespread channelization and woody debris removal (Kapsch, 2010).…”

Landscape features and study design affect elements of metacommunity structure for stream fishes across the eastern U.S.A.

“…The result of these affects should be decreased coherence, turnover, and boundary clumping (Table 1). Because headwater stream fish assemblages are often represented as nested subsets of richer downstream assemblages, we hypothesise (3) the changes in elevation and temperature within a catchment will have a negative relationship with coherence, turnover, and boundary clumping because in our study system, headwater streams are generally at a higher elevation with cooler water temperature and are often more isolated than downstream reaches (Brown et al., 2011; Midway & Peoples, 2019). We lastly hypothesise (4) a positive relationship between fluvial distance among local communities, number of local communities, and γ diversity and coherence, turnover, and boundary clumping (Table 1).…”