Partial decoupling between exotic fish and habitat constraints remains evident in late invasion stages

Milardi, Marco; Gavioli, Anna; Castaldelli, Giuseppe; Soininen, Janne

doi:10.1007/s00027-019-0688-2

Cited by 6 publications

(4 citation statements)

References 65 publications

(73 reference statements)

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“…As a result, their invasion distributions perhaps are the result of spread and subsequent selection by unsuitable habitat. Habitat-induced selection requires at least decadal timescales 42 , and involve other factors such as species origin, invasiveness potential and overall available habitat 43 , which could partially explain why no clear patterns were immediately evident (see Table 1 ) between time since introduction and invasiveness rank and confirming that most introduced species in our study are in late invasion stages. It is perhaps worthy to note that species invasiveness can vary through time, so that species that ranked high in our analysis could have been either more or less invasive at different invasion stages, including the current situation.…”

Section: Discussionmentioning

confidence: 55%

Natural and anthropogenic factors drive large-scale freshwater fish invasions

Milardi

Iemma²,

Waite

et al. 2022

Sci Rep

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We analyzed the large-scale drivers of biological invasions using freshwater fish in a Mediterranean country as a test case, and considering the contribution of single species to the overall invasion pattern. Using Boosted Regression Tree (BRT) models, variation partitioning and Redundancy Analysis (RDA), we found that human factors (especially eutrophication) and climate (especially temperature) were significant drivers of overall invasion. Geography was also relevant in BRT and RDA analysis, both at the overall invasion and the single species level. Only variation partitioning suggested that land use was the second most significant driver group, with considerable overlap between different invasion drivers and only land use and human factors standing out for single effects. There was general accordance both between different analyses, and between invasion outcomes at the overall and the species level, as most invasive species share similar ecological traits and prefer lowland river stretches. Human-mediated eutrophication was the most relevant invasion driver, but the role of geography and climate was at least equally important in explaining freshwater fish invasions. Overall, human factors were less prominent than natural factors in driving the spread and prevalence of invasion, and the species spearheading it.

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Section: Discussionmentioning

confidence: 55%

Natural and anthropogenic factors drive large-scale freshwater fish invasions

Milardi

Iemma²,

Waite

et al. 2022

Sci Rep

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“…Where present, it tends to dominate the community of predator fishes (~ 30% of the whole fish community biomass, M. Milardi, unpublished data). Wels catfish and other introduced fish species are a major problem also for native fish diversity in Italian freshwaters (Milardi et al 2018(Milardi et al , 2019a(Milardi et al , 2020a(Milardi et al , 2020b(Milardi et al , 2020c, but to date, little has been done to address this problem. A recent review by Cucherousset et al (2018) underlined how the species is widespread and abundant also in the rest of its introduced range (e.g.…”

Section: Discussionmentioning

confidence: 99%

Invasive catfish in northern Italy and their impacts on waterbirds

Milardi¹,

Green²,

Mancini³

et al. 2022

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Predatory fish have occasionally been observed preying on birds, sometimes repeatedly, but few studies were able to unravel the overall significance of avian prey in fish diet and the predation impacts on bird populations. We used a control/impact study setup, using a Nature Reserve in northern Italy and a nearby control area, to determine: 1) the contribution of waterbirds to wels catfish diet in the Reserve, 2) the population density of wels catfish in the Reserve and control area and 3) the potential impacts of waterbird depredation by wels catfish on waterbird population trends. Our stable isotope Bayesian mixing model indicated that birds contributed 12.2% (5–27.9%, 50% confidence interval) of the diet of large wels catfish (> 98 cm in total length). Large individuals constituted the majority of the population in the shoreline areas of the reserve in 2013–2019, where the population was stable despite control efforts. Numbers were below detectable levels in the control area. Large wels catfish consumed an average of 224, 148 and 187 kg of birds during the 2019 chick growing period, as estimated through three different bioenergetic models. Compared to the control area, mallard reproductive success was diminished in the Reserve, likely due to higher rates of fish predation, although effects were variable in different years. Overall, our data suggest that high densities of invasive wels catfish might impact waterbird reproductive success through predation on bird chicks, but further studies would be needed to reduce uncertainties related to the intrinsic variability of field ecology data. Our study constitutes a preliminary attempt to assess the potential of introduced wels catfish to affect the conservation value of waterbird protection areas, and should be repeated at broader spatial and temporal scales.

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“…disturbances, acidification, etc. ; Milardi, Gavioli, Castaldelli, et al., 2020; Milardi et al., 2022), can drive a rapid increase in dispersal in a subset of populations, which may then also be more likely to spread to other human‐impacted environments and establish (Borden & Flory, 2021; Hufbauer et al., 2012). The variability in how different populations respond to these local or regional factors (Figure 1b), and the ways an invasion is perceived, may change depending on the perspective (local insular population‐level versus larger regional meta‐population species‐level perspective; Figure 1c).…”

Section: Introductionmentioning

confidence: 99%

Biological invasions are a population‐level rather than a species‐level phenomenon

Haubrock,

Soto,

Ahmed

et al. 2024

Global Change Biology

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Biological invasions pose a rapidly expanding threat to the persistence, functioning and service provisioning of ecosystems globally, and to socio‐economic interests. The stages of successful invasions are driven by the same mechanism that underlies adaptive changes across species in general—via natural selection on intraspecific variation in traits that influence survival and reproductive performance (i.e., fitness). Surprisingly, however, the rapid progress in the field of invasion science has resulted in a predominance of species‐level approaches (such as deny lists), often irrespective of natural selection theory, local adaptation and other population‐level processes that govern successful invasions. To address these issues, we analyse non‐native species dynamics at the population level by employing a database of European freshwater macroinvertebrate time series, to investigate spreading speed, abundance dynamics and impact assessments among populations. Our findings reveal substantial variability in spreading speed and abundance trends within and between macroinvertebrate species across biogeographic regions, indicating that levels of invasiveness and impact differ markedly. Discrepancies and inconsistencies among species‐level risk screenings and real population‐level data were also identified, highlighting the inherent challenges in accurately assessing population‐level effects through species‐level assessments. In recognition of the importance of population‐level assessments, we urge a shift in invasive species management frameworks, which should account for the dynamics of different populations and their environmental context. Adopting an adaptive, region‐specific and population‐focused approach is imperative, considering the diverse ecological contexts and varying degrees of susceptibility. Such an approach could improve and refine risk assessments while promoting mechanistic understandings of risks and impacts, thereby enabling the development of more effective conservation and management strategies.

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Partial decoupling between exotic fish and habitat constraints remains evident in late invasion stages

Cited by 6 publications

References 65 publications

Natural and anthropogenic factors drive large-scale freshwater fish invasions

Natural and anthropogenic factors drive large-scale freshwater fish invasions

Invasive catfish in northern Italy and their impacts on waterbirds

Biological invasions are a population‐level rather than a species‐level phenomenon

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Partial decoupling between exotic fish and habitat constraints remains evident in late invasion stages

Cited by 6 publications

References 65 publications

Natural and anthropogenic factors drive large-scale freshwater fish invasions

Natural and anthropogenic factors drive large-scale freshwater fish invasions

﻿Invasive catfish in northern Italy and their impacts on waterbirds

Biological invasions are a population‐level rather than a species‐level phenomenon

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Invasive catfish in northern Italy and their impacts on waterbirds