Invasive ascidians: How predators reduce their dominance in artificial structures in cold temperate areas

Light, shade and predation: who wins and who loses in sessile fouling communities?

“…Such control of fouling communities by fish predation has previously been noted, especially in those dominated by ascidians (Koplovitz and McClintock 2011;Kremer and da Rocha 2016;Hiebert et al 2019). Although this study focused on nektonic predators, it is important to acknowledge that benthic predators can also play an important role in regulating sessile communities and ascidians in particular (Dumont et al 2011;Giachetti et al 2020). Typically, this effect is observed in relation to benthic macropredators such as sea urchins, gastropods and crabs (Simkanin et al 2013;Leclerc et al 2020).…”

“…The results obtained in this study suggest that, in contrast to colonial ascidians, solitary taxa could be more influenced by predation, since they reached highest abundances on caged panels where predators were excluded. Other studies have demonstrated the strong effects of predators such as fish over solitary ascidians including Ascidiella aspersa, Ciona robusta and Corella eumyota (Dumont et al 2011;Giachetti et al 2020;Leclerc et al 2020). These ascidians are particularly vulnerable to predation during early life stages when their small size allows predation by most invertebrate and fish predators (Osman and Whitlatch 2004;Rius et al 2014) and when they are less likely to survive any damage sustained during a nonfatal predation event (Jackson and Hughes 1985).…”

New invasive predator reduces the abundance of native prey in a cold‐temperate marine fouling community

“…), anthozoans ( Corynactis carnea Studer, 1879, Actinothoe lobata (= Metridium senile lobatum ) (Carlgren, 1899) and Anthothoe chilensis (Lesson, 1830)) and ascidians ( Asterocarpa humilis (Heller, 1878), Ascidiella aspersa (Müller, 1776) and Ciona robusta (Hoshino & Tokioka, 1967)), which create a complex three‐dimensional structure that harbours various species of native and introduced gastropods, decapods, polychaetes and echinoderms, among others (Giachetti et al, 2019). The main macropredators are benthic generalist species such as the echinoderms Arbacia dufresnii (Blainville, 1825) and Allostichaster capensis (Perrier, 1875), the crab Leucippa pentagona H. Milne Edwards, 1834, the snail Tegula patagonica (d’Orbigny, 1835), the small fish Helcogrammoides cunninghami (Smitt, 1898) and the sea slug P. maculata (Giachetti et al, 2019; Giachetti et al, 2020). The latter represents one of the most abundant macropredators within the port area, where it concentrates mainly over the pilings (see Supporting Information).…”

Greater functional similarity in mobile compared to sessile assemblages colonizing artificial coastal habitats

“…Comparing natural vs. artificial habitats, some studies documented differing species compositions (Connell 2000, Glasby and Connell 2001, Holloway and Connell 2002, Sedano et al 2020 and contrasting functional patterns between them (Mayer-Pinto et al 2018, Janiak andBranson 2021). Similarly, among different types of artificial structures, differences in community composition and biotic interactions have also been shown (Connell 2001, Firth et al 2016, Rogers et al 2016, Strain et al 2018, Giachetti et al 2020. For instance, floating structures, such as buoys, pontoons or floating longlines, present contrasting species assemblages to those found on non-floating structures, such as the pillars of piers or docks (Connell 2001, Glasby 2001, Holloway and Connell 2002, and can differ in their β-diversity across multiple spatial scales (Leclerc et al 2020a).…”

“…For instance, floating structures, such as buoys, pontoons or floating longlines, present contrasting species assemblages to those found on non-floating structures, such as the pillars of piers or docks (Connell 2001, Glasby 2001, Holloway and Connell 2002, and can differ in their β-diversity across multiple spatial scales (Leclerc et al 2020a). The various studies that have tried to understand the mechanisms behind these differences have attributed them not only to the aforementioned physical properties of the structures but also to those to which these structures are subjected (e.g., water motion, connectivity with the benthos, exposure to predators and scavengers, disturbance regimes; Glasby 2001, Holloway and Connell 2002, Giachetti et al 2020. Hence, the differing conditions to which floating versus non-floating structures are subjected could act as filters for certain functional traits among the resulting assemblages (see Piola and Johnston 2009, Zhan et al 2015, Aronson et al 2016.…”