Life‐history traits and temporal patterns in the incidence of coastal fishes experiencing tropicalization

Abstract

Climate change is causing shifts in the geographic distributions of coastal fish species toward higher latitudes. However, local fish communities found in higher latitudes today are not simply those found in lower latitudes in the past because the sensitivity of species to various environmental conditions is different. Responses of fish to environmental conditions differ depending on their life-history traits such as the maximum population growth rate, age of maturity, and generation time because these traits are constrained by environmental conditions. Here, we investigate associations among temporal patterns in presence-absence (incidence) data, life-history traits of species, and environmental conditions to elucidate the potential mechanisms behind the effects of climate change on coastal fish communities. In this study, fish monitoring data collected semi-monthly between 1982 and 2019 from eight major bays in the northwestern Gulf of Mexico were analyzed with generalized additive models. Smooth patterns over seasons and years in the incidence data of 77 species were estimated, and the data were associated with environmental variables. Further, these temporal patterns were associated with the life-history traits of species. The results show that species that are more common in the summer months (non-winter spawners) tend to exhibit an increasing trend and that species common during the spring (winter spawners) tend to exhibit a decreasing trend, suggesting the importance of summer conditions in driving tropicalization. Salinity had significant effects on species in general, and longer-lived species tended to be affected by temperature. These results suggest seasonal differences in the effects of environmental conditions and variation in sensitivity to environmental conditions among different life-history strategies. These findings represent major steps toward understanding the mechanisms behind the tropicalization of estuarine communities.

Changes in species compositions of fish in the bays of the Northwestern Gulf of Mexico

“…The observed temporal changes in species compositions (Figure 4) may still be explained by temperature although it does not appear as a significant factor in our statistical analysis. This is because water temperature is rising along the coast and the relationship between temperature and abundance of species may be non-linear (Fujiwara et al, 2022). Temperature influences the distribution of fish along a latitudinal gradient (Harley et al, 2006;O'Connor and Booth, 2021) as ectothermic species rely on environmental temperature for their physiological functioning (Little et al, 2020;Liao et al, 2021).…”

“…In the Northwestern Gulf of Mexico (GOM), the Shannon diversity index (Spellerberg and Fedor, 2003) in major bays has increased in the past 30 years (Fujiwara et al, 2019;Pawluk et al, 2021) while functional diversity among fishes has declined (Pawluk et al, 2022). Furthermore, fish species that spawn during late spring and summer were shown to have a greater tendency to increase their abundance than those that spawn in other seasons (Fujiwara et al, 2022). These results are starting to reveal the spatiotemporal dynamics of species compositions in the Northwestern GOM.…”

Quantifying the ecological consequences of climate change in coastal ecosystems

“…Pinsky et al (2020) provide a detailed discussion of potential explanations for this phenomenon, including physiology, behaviour, evolution, dispersal and species interactions, but answers are elusive, and this question remains a topic of active research (e.g., Usui et al, 2023). Nevertheless, arguably the most ubiquitous consequence of differential range shifts at leading and trailing range edges is the arrival of warm-affinity species in communities previously dominated byand still occupied byspecies of cooler provenance (Vergés et al, 2014;Chaudhary et al, 2021;Favoretto et al, 2022;Fujiwara et al, 2022). This process, known in low-to mid-latitudes as tropicalisation, in combination with the closely related process of deborealisationthe loss of cool-associated species from highlatitude placesresults in the continual reassembly of biotic communities in coastal waters (McLean et al, 2021).…”