Community dynamics of estuarine forage fishes are associated with a latitudinal basal resource regime

Abstract

Forage fishes are an important component of marine, estuarine, and aquatic food webs that facilitate the transfer of energy and nutrients from primary producers to upper trophic levels. Previous studies of forage fishes have focused primarily on pelagic planktivorous species in pelagic environments. However, benthically associated taxa can be just as important as planktivorous species, particularly in highly productive estuarine environments that provide critical habitat for many predators. In this study, we analyzed a 20‐year forage fish community composition and abundance dataset across four eastern Gulf of Mexico estuaries spanning a broad latitudinal gradient to investigate spatiotemporal variability in community structure and quantify associations with habitat. Our analyses revealed significant regional structuring of forage fish communities, coupled with a strong association with habitat characteristics related to latitudinal effects and basal resource regime. Communities in the two northern estuaries and two southern estuaries were associated primarily with planktonically reliant and benthically reliant taxa, respectively. Despite regional differences, we uncovered a coherent annual cycle in forage fish communities across all estuaries related to seasonal shifts in abundances of several abundant and ubiquitous species. We additionally revealed significant subdecadal periodicity potentially associated with bottom‐up effects of global climatic cycles. The significant association of forage fish communities with habitat regime shown in this study underlies the importance of continued monitoring of these communities. This study represents a novel approach to assess this critical ecosystem component in diverse estuarine systems globally.

Characterizing a regional fishery ecosystem trajectory: the Humpty Dumpty fish tale of the U.S. Gulf of Mexico from 1986 to 2013

“…As previously noted, the LTL resources modeled in this exercise were closely related to the primary axis of the RDA model (Figure 4), as were the majority of the federally managed UTL species included (Figure 4). Additionally, climatic variability has recently been shown to differentially affect many of this study's UTL species across the long-term (Geraldi et al, 2019), while many short-lived forage species (e.g., Gulf Menhaden) and other LTL resources in the region have also been observed to differentially respond to climate-related variability, albeit on somewhat shorter timescales (Peake et al, 2022). In the GoM LME, Gulf Menhaden are an important prey species for key predators in this study, such as King and Spanish Mackerel, sharks, and other coastal piscivores (Berenshtein et al, 2023) like Red Grouper or Gag, while the population supports the largest commercial reduction fishery in the region (NMFS, 2023).…”

Trophic ontogeny of a generalist predator is conserved across space

“…Prey heterogeneity across this region may also re ect a gradient in basal-resource dependence from more phytoplankton-based food webs at higher, eutrophic latitudes to greater dependence on benthic food webs at lower, oligotrophic latitudes (Radabaugh et al 2013;Lesser et al 2020;Peake et al 2022). Because this region covers the geographic center of this generalist predator's distribution across which prey heterogeneity has been shown to exist, this is an ideal model system to test whether and how ontogenetic changes in trophic ecology vary across local populations.…”

Global expression pattern of genes containing positively selected sites in European anchovy (Engraulis encrasicolus L.) may shed light on teleost reproduction

“…According to FAO (2019) estimates, global capture production of anchovies (combining data from 3 species: E. ringers, E. japonicus and E. encrasicolus) was estimated at about 7 million tones per year between 2015 and 2019 (https://www.fao.org/fishery/en/ statistics). From an ecological standpoint, large schools of anchovies predominantly occupy the mid-trophic level of the food chain, transferring energy and nutrients from zooplankton (even phytoplankton) to higher trophic levels [4][5][6]. High-productive capacity (i.e., excessive egg production), early maturation and feeding on a wide range of prey may contribute to the apparent ecological success of anchovies despite their short lifespan.…”