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{"Abstract":["Stomach contents of fishes (1977-1981) and stable isotopes of fishes, invertebrates, and basal resources (1994) were collected from spikerush marsh, sawgrass ridge, and alligator pond habitats in Shark River Slough, Everglades National Park, Florida, USA. These data were used to quantify diet, trophic niche area, trophic position, basal resource use and how these metrics vary among size classes, seasons, and habitats. Data collection is complete. These data support Flood et al. (2023). Associated R code will be made available through Peter Flood's GitHub: https://github.com/pjflood/historic_everglades_aquatic_food_web. \n References:\n Flood, Peter J., William F. Loftus, and Joel C. Trexler. "Fishes in a seasonally pulsed wetland show spatiotemporal shifts in diet and trophic niche but not shifts in trophic position." Food Webs 34 (2023): e00265. https://doi.org/10.1016/j.fooweb.2022.e00265"]} 

Irruptive or boom-and-bust population dynamics, also known as ‘outbreaks’, are an important phenomenon that has been noted in biological invasions at least since Charles Elton’s classic book was published in 1958. Community-level consequences of irruptive dynamics are poorly documented and invasive species provide excellent systems for their study. African Jewelfish (Rubricatochromis letourneuxi, “jewelfish”) are omnivores that demonstrate opportunistic carnivory, first reported in Florida in the 1960s and in Everglades National Park (ENP) in 2000. Twelve years after invasion in ENP, jewelfish underwent a 25-fold increase in density in one year. By 2016, jewelfish represented 25–50% of fish biomass. Using a 43-year fish community dataset at two sites (1978–2021), and a 25-year dataset of fish and invertebrate communities from the same drainage (1996–2021), with additional spatial coverage, we quantified differences in fish and invertebrate communities during different phases of invasion. During jewelfish boom, abundant, native cyprinodontiform fishes decreased in density and drove changes in community structure as measured by similarity of relativized abundance. Density of two species declined by > 70%, while four declined by 50–62%. Following the jewelfish bust, some species recovered to pre-boom densities while others did not. Diversity of recovery times produced altered community structure that lagged for at least four years after the jewelfish population declined. Community structure is an index of ecological functions such as resilience, productivity, and species interaction webs; therefore, these results demonstrate that irruptive population dynamics can alter ecological functions of ecosystems mediated by community structure for years following that population’s decline. 

Abstract The Trophic Disruption Hypothesis (TDH) predicts that invasive species may cause native species to undergo trophic dispersion (change in trophic‐niche area) and trophic displacement (diet switching), predictably altering food‐web structure and biodiversity. In Everglades National Park, Florida, USA, African Jewelfish (Rubricatochromis letourneuxi) density has recently (2012–2017) undergone a boom‐bust cycle, linked to declines of native taxa and altered aquatic‐community composition that persist after the bust. Everglades restoration efforts seek to restore historic hydrologic conditions that may contribute to food‐web changes unfolding coincidentally with the jewelfish boom. We used complementary datasets of stomach contents and stable isotopes (δ¹⁵N and δ¹³C) to quantify pre‐ and post‐invasion consumer diets, trophic positions, trophic niches, basal energy use (autotrophic vs. heterotrophic), and energy fluxes to test assumptions of the TDH. The direction of change for these metrics from dry season to wet‐season post‐invasion (i.e., effect of adding water) was used as a proxy for the direction of effects from restored water delivery. For trophic shifts attributable to jewelfish invasion, we tested assumptions of the TDH. Comparing pre‐ versus post‐invasion for native consumers, we observed trophic displacement in 42% of species size classes (based on stomach contents), trophic dispersion for 57% of species (based on stable isotopes) and 54% of species size classes (based on stomach contents), and overall greater reliance on autotrophic energy. Altered trophic dynamics were more frequent pre‐ versus post‐invasion than among habitats or between seasons, and the direction of those responses was in the opposite direction of dry‐season to wet‐season differences and/or occurred at a higher frequency. Post‐invasion food‐web structure and function revealed increased relative abundance of mesopredators (including African Jewelfish) and reduced biomass and energy fluxes into and out of small fishes (e.g., Cyprinodontiformes). Our results show that African Jewelfish invasion is linked to altered spatiotemporal trophic dynamics and energy fluxes through declines in native fishes and invertebrates, which indirectly affected trophic relationships at the regional scale in the Everglades. As a result, we suggest extending the TDH to explicitly include the potential for invasive species to alter basal energy use, spatiotemporal trophic dynamics, and energy fluxes. 

Recruitment has been linked to decreases in the ratio of age-specific mortality (M′) to mass-specific growth (G′), and year-class strength may be predicted by the age when M′/G′ = 1. Hydrological stress adversely affects these parameters for species inhabiting floodplains; however, the relationship between M′ and G′ in hydrologically variable environments is poorly understood. We evaluated age-specific mortality for six species from a 20-year time series and growth curves from otolith length-at-age data. We assessed the effect of hydrology on the transitional age (age M′/G′ = 1) at 21 sites representing a hydrological gradient. Disturbance intensity influenced age-specific mortality but had no effect on mass-specific growth. The transitional age was inversely correlated with annual density, but weakly associated with population biomass. Hydrological disturbance shifted the transitional age to older ages, reducing recruitment overall. We demonstrated that the M′/G′ transition was affected adversely by hydrological stress and can be applied to a diverse group of taxa. Growth, survivorship, and the transitional age should be evaluated to improve population modelling efforts used to predict the influence of future restoration actions.