Climate-associated trends and variability in ichthyoplankton phenology from the longest continuous larval fish time series on the east coast of the United States

Abstract

As the effects of climate change become more pronounced, variation in the direction and magnitude of shifts in species occurrence in space and time may disrupt interspecific interactions in ecological communities. In this study, we examined how the fall and winter ichthyoplankton community in the Newport River Estuary located inshore of Pamlico Sound in the southeastern United States has responded to environmental variability over the last 27 yr. We relate the timing of estuarine ingress of 10 larval fish species to changes in sea surface temperature (SST), the Atlantic Multidecadal Oscillation, the North Atlantic Oscillation, wind strength and phenology, and tidal height. We also examined whether any species exhibited trends in ingress phenology over the last 3 decades. Species varied in the magnitude of their responses to all of the environmental variables studied, but most shared a common direction of change. SST and northerly wind strength had the largest impact on estuarine ingress phenology, with most species ingressing earlier during warm years and delaying ingress during years with strong northerly winds. As SST warms in the coming decades, the average date of ingress of some species (Atlantic croaker Micropogonias undulatus, summer flounder Paralichthys dentatus, pinfish Lagodon rhomboides) is projected to advance on the order of weeks to months, assuming temperatures do not exceed a threshold at which species can no longer respond through changes in phenology. These shifts in ingress could affect larval survival and growth since environmental conditions in the estuarine and pelagic nursery habitats of fishes also vary seasonally.

Four decades of climatic fluctuations and fish recruitment stability across a marine‐freshwater gradient

“…Fish communities in estuaries tend to track climatic variability through space and time (Cloern et al, 2010; Feyrer et al, 2015; Pollack et al, 2011), suggesting that climate change may result in “winners” and “losers” (Somero, 2010). Multiple stressors may exceed species' physiological thresholds (Lauchlan & Nagelkerken, 2020), shift phenologies (Thaxton et al, 2020), amplify matches or mismatches with food resources (Asch, 2015; Chevillot et al, 2017), or exacerbate human impacts such as habitat loss (Moyle et al, 2013) or fishing pressure (Griffith et al, 2012). Extreme events may homogenize environmental gradients (e.g., strong storms that freshen the entire estuary or prolonged droughts that elevate salinity levels far upstream; Ghalambor et al, 2021), and in doing so, they may synchronize population dynamics via the Moran effect (i.e., regionally coordinated environmental fluctuations; Moran, 1953).…”

Ontogenetic Changes in Behavioral and Energetic Responses of Juvenile Atlantic Croaker to an Estuarine Salinity Gradient

“…Temperature increases cause changes in the phenology (timing of immigration and emigration) of fishes into and out of estuaries, whereby summer residents generally exhibit earlier ingress and later egress, a global response pattern across taxa (Poloczanska et al 2013;Langan et al 2021). Summer temperatures that exceed a species' thermal tolerance threshold, however, would likely affect the phenological response by causing egress to occur earlier (Neuheimer et al 2011;Thaxton et al 2020). Warming will likely cause earlier larval ingress and up-estuary movement by young Atlantic Croakers to oligohaline nursery areas.…”

“…Warming will likely cause earlier larval ingress and up-estuary movement by young Atlantic Croakers to oligohaline nursery areas. In fact, on the southeastern United States coast, the beginning of larval ingress of Atlantic Croakers and other species is already shifting earlier in warmer years, resulting in longer ingress duration (Thaxton et al 2020). Projections of future ingress shift, in response to 2°C warming, are approximately 4 weeks for Atlantic Croaker.…”

“…2011; Thaxton et al. 2020). Warming will likely cause earlier larval ingress and up‐estuary movement by young Atlantic Croakers to oligohaline nursery areas.…”

Climate Change Implications for Tidal Marshes and Food Web Linkages to Estuarine and Coastal Nekton

“…In addition, the timing of peak nekton abundance may shift in response to changing environmental conditions. In the southeastern USA, for example, the timing of peak ingress of larval fishes [e.g., Atlantic croaker (Micropogonias undulates), summer flounder (Paralichthys dentatus), pinfish] from the coastal ocean to estuarine nurseries is shifting earlier in warm years, with projections of future shifts in response to warming SST on the order of weeks or months, but is delayed in years with strong northerly winds (Thaxton et al 2020). Physiological performance (e.g., growth, calcification, maximum body size), behavior (e.g., predator detection, escape response, freshwater dependence), and inter-and intraspecific competition and non-consumptive indirect effects may also be affected by climate change (Miller et al 2000;Pörtner and Peck 2010;Nagelkerken and Munday 2016).…”