Between-habitat variability in the population dynamics of a global marine invader may drive management uncertainty

Epstein, Graham; Smale, Dan

doi:10.1016/j.marpolbul.2018.10.055

Cited by 7 publications

(10 citation statements)

References 77 publications

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“…S1) illustrate this snowball effect. The densities observed in the marina of Bloscon at the end of this study are similar to what have been observed in other marinas in the English Channel (Epstein, Smale 2018a;Epstein, Smale 2018b;Murphy et al 2016b).…”

Section: A Snow-ball Colonization Dynamicssupporting

confidence: 88%

“…In addition, selfing, which is reaching 36% in this established population (Table 1) can accentuate this effect through rapid space monopolization, as shown by the short dispersal distance between full-sibs (<20m). This local recruitment could have occurred from the presence of dormant gametophytes and/or reproduction of overwintering mature sporophytes (Epstein, Smale 2018a). Dormancy in gametophytes of kelps usually do not exceed a few months (Hoffmann, Santelices 1991), but data on the maximum extent of dormancy in Undaria gametophytes is lacking.…”

Section: Spill-back Effects Are Followed By a Shift Towards A Self-sumentioning

confidence: 99%

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Spill-back events followed by self-sustainment explain the fast colonization of a newly built marina by a notorious invasive seaweed

et al. 2020

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Biological invasions are occurring at increasing rates since the onset of the th century. While ports and marinas have been identified as a major point-of-entry for the spread of marine non-indigenous species (NIS), their relationships with wild habitats however needs further scrutiny. We had the rare opportunity to monitor the real-time colonization dynamics of a newly-built marina by the notorious invasive kelp Undaria pinnatifida in the Bay-of-Morlaix, Brittany (France). Field surveys (>20 000 individuals geo-localized) were combined with genetic analyses (10 microsatellite loci, N=890 individuals) over three years (i.e., 6 generations in the study area). Regarding the colonization dynamics, a dramatic snowball effect was documented over time, with local density reaching up to 50 individuals per m after two years. Assignment tests showed that the primary colonizers came from neighboring populations established in natural rocky reefs. A shift towards a self-sustaining population was however observed the following year, with 44% of self-assignment. These processes are best explained by i) life history traits, notably rapid growth and selfing, and ii) natural dispersal within the marina combined with human-mediated dispersal-through leisure boating-over longer distances. Spill-over effects have been previously documented, and here also reported, to explain the expansion of U. pinnatifida from marinas to the wild. We showed that the ongoing ocean sprawl also offers a perfect arena for spill-back events (i.e., spread from natural habitats to artificial structures), highlighting the need for careful surveillance of newly built infrastructures.

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Section: A Snow-ball Colonization Dynamicssupporting

confidence: 88%

Section: Spill-back Effects Are Followed By a Shift Towards A Self-sumentioning

confidence: 99%

Spill-back events followed by self-sustainment explain the fast colonization of a newly built marina by a notorious invasive seaweed

et al. 2020

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“…This study adds further support to the importance of artificial habitats in the invasion pathway of Undaria both across regions and locally into adjacent natural habitats 24,42,68 . The optimal habitat for Undaria within this study region appears to be floating pontoons in marinas – a habitat that has no natural analogue 69 .…”

Section: Discussionmentioning

confidence: 99%

“…All nine monitoring sites (Marinas: 1–3; Intertidal rocky-reef: Devil’s Point, Firestone Bay, West Hoe; Subtidal rocky-reef: Devil’s Point, Firestone Bay, West Hoe) were sampled over a two week period at each sampling event. Although Undaria can be found throughout the year in the UK 69 it has an annual life-history, predominantly being found in late spring to early summer 26,60,63,69 when sampling intensity was concentrated. Sampling in September and December 2016 and March 2017 explored seasonal patterns in density and biomass.…”

Section: Methodsmentioning

confidence: 99%

Identifying niche and fitness dissimilarities in invaded marine macroalgal canopies within the context of contemporary coexistence theory

Epstein

Hawkins

Smale

2019

Sci Rep

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Contemporary coexistence theory provides a framework for predicting invasiveness and impact of Invasive Non-Native Species (INNS) by incorporating differences in niche and fitness between INNS and co-occurring native species. The widespread invasive kelp Undaria pinnatifida is considered a high-risk INNS, although a robust evidence base regarding its invasiveness and impact is lacking in many regions. Invaded macroalgal canopies at nine coastal sites in the southwest UK were studied over three years to discern whether Undaria is coexisting or competing with native canopy-forming species across different habitat types. Spatial, temporal and depth-related trends in species distributions and abundance were recorded within intertidal and subtidal rocky reef as well as on marina pontoons. A primary succession experiment also examined competitive interactions between species. In rocky reef habitats, Undaria had lower fitness compared to long-lived native perennials, but was able to coexist due to niche dissimilarity between species. In contrast, Undaria was likely to be competing with short-lived native annuals on rocky reef due to large niche overlap and similar fitness. In marina habitats, Undaria dominated over all other canopy formers due to low niche diversification and higher fitness. Generalisations on INNS impact cannot be made across habitats or species, without considering many abiotic factors and biotic interactions.

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“…Both Undaria and S. polyschides are annual species that exhibit marked seasonality in recruitment, maturation, growth, and senescence at similar times of year. Typically, sporophytes of both species recruit during early spring, grow throughout summer, and senesce in autumn (Norton and Burrows , Fletcher and Farrell , Epstein and Smale ). Spatially, they occupy a similar niche in the subtidal fringe and are both considered relatively opportunistic species (Norton and Burrows , Castric‐Fey et al.…”

Section: Discussionmentioning

confidence: 99%

Inconspicuous impacts: Widespread marine invader causes subtle but significant changes in native macroalgal assemblages

2019

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Invasive species are a major cause of global biodiversity decline; however, under certain environmental settings, some invaders can co‐exist with native species with little detectable impact. Even so, in many cases the realized impact of invasive species may be underestimated due to procedural or temporal constraints related to observation or experimentation. The invasive kelp, Undaria pinnatifida, is considered to have limited impact on macroalgal assemblages on rocky reefs of the northeast Atlantic, although this is largely based on correlative or observational findings. Here, a high intensity press‐removal manipulation was maintained for two years at a heavily invaded, Undaria dominated study site to improve current understanding of the potential impacts of Undaria on native macroalgal assemblages. Population and community effects as well as organismal performance effects (biochemical measures of condition and stress) were examined to investigate the potential for cryptic impacts. Where Undaria was removed, there was no difference in understory macroalgal assemblages; however, for three native kelp species, significant increases in abundance, biomass, and condition were recorded. The two perennial native kelps (Laminaria digitata and Saccharina latissima) exhibited small and inconsistent increases in all impact metrics where Undaria was removed, and therefore, the overall effects of Undaria on their populations are likely to be negligible. However, the native annual kelp, Saccorhiza polyschides, was consistently and significantly higher (3–6 times when compared to controls) in abundance and biomass under reduced competition from Undaria and exhibited significant changes in organismal‐level responses which indicated improved condition of sporophytes. Whether the potential replacement of this native species could alter ecosystem functioning requires further investigation. Targeted long‐term manipulative experiments can identify previously undetected impacts of invasive species in coastal ecosystems. Caution must be used when broadly classifying invasive species as having limited ecological impacts on recipient communities. Subtle impacts manifesting at the organism, population, and community levels should be considered before robust management prioritizations can be made.

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Between-habitat variability in the population dynamics of a global marine invader may drive management uncertainty

Cited by 7 publications

References 77 publications

Spill-back events followed by self-sustainment explain the fast colonization of a newly built marina by a notorious invasive seaweed

Spill-back events followed by self-sustainment explain the fast colonization of a newly built marina by a notorious invasive seaweed

Identifying niche and fitness dissimilarities in invaded marine macroalgal canopies within the context of contemporary coexistence theory

Inconspicuous impacts: Widespread marine invader causes subtle but significant changes in native macroalgal assemblages

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