Search

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 FROM AUTHOR]

Non-native species can simultaneously affect ecological structures, functions, and services of the invaded ecosystem. In this paper, we report that the study of non-native species impacts on ecosystem function is an emerging topic in aquatic ecology, though studies measuring functions remain relatively uncommon. We hypothesized that study of ecosystem function can reveal emergent effects of non-native species when community structure appears to be unimpacted and the study of multiple functions has the potential to identify impacts masked by food-web complexity. We compiled information from Web of Science to create a pool of papers (n = 199) addressing ecosystem functions and services that we surveyed to evaluate our hypotheses. The number of publications referencing ecosystem function has increased since 2002, but only 10% of papers measured ecosystem functions as defined in our work. Additionally, 80% of publications reporting functional metrics addressed primary production and nutrient fluxes, while a low number of manuscripts (6%) directly linked the impact of non-native species on ecosystem functions to ecosystem services. We recommend future work focus on less-studied functions (e.g., bioturbation, decay rate, biomagnification), assess multiple functional metrics, link functions to services, and use networks to understand impacts from multiple dimensions of an invaders ecology. [ABSTRACT FROM AUTHOR]