Abstract
Variation in density of early stages, that is, larvae and juveniles, is a major determinant of the distribution and abundance of the adult population of most marine invertebrates. These early stages thus play a key role in competitive interactions, and, more specifically, in invasion dynamics when biologically similar native and non‐native species (NNS) come into contact in the same habitat. We examined the settlement dynamics and settlement rate of two important members of the fouling community that are common on human‐made infrastructures around the world: Ciona robusta (formerly known as Ciona intestinalis type A) and C. intestinalis (formerly known as C. intestinalis type B). In the western English Channel, the two species live in close syntopy following the recent introduction of C. robusta in the native European range of C. intestinalis. Using settlement panels replaced monthly over 2 years in four marinas (including one studied over 4 years) and species‐diagnostic molecular markers to distinguish between juveniles of both species (N = 1,650), we documented similar settlement dynamics of both species, with two settlement periods within a calendar year. With one exception, settlement times were highly similar in the congeners. Although the NNS showed lower settlement density than that of the native congener, its juvenile recruitment was high during the second settlement period that occurs after the warm season, a pattern also observed in adult populations. Altogether, our results suggest that species’ settlement dynamics do not lead to the dominance of one species over the other through space monopolization. In addition, we showed that changes over time are more pronounced in the NNS than in the native species. This is possibly due to a higher sensitivity of the NNS to changes of environmental factors such as temperature and salinity. Environmental changes may thus eventually modify the strength of competitive interactions between the two species as well as species dominance.
Highlights
Coastal man-made infrastructures, such as harbors, marinas, or aquaculture facilities, are growing in number and in size and are modifying marine coastal landscapes at an unprecedented rate around the world (Airoldi & Beck, 2007; Bulleri & Chapman, 2010)
The two species are important members of fouling communities and well established in artificial habitats including marinas and harbors worldwide (Aldred & Clare, 2014; Bouchemousse, Lévêque, Dubois, & Viard, 2016; Lambert & Lambert, 1998; Ramsay, Davidson, Landry, & Arsenault, 2008; Tracy & Reyns, 2014). They live in syntopy in several marinas in the western English Channel and southern Brittany in the Northeast Atlantic (Bouchemousse, Lévêque, et al, 2016; Nydam & Harrison, 2011)
We showed a very low relative abundance of C. robusta in spring compared with autumn. This variation can be attributed to differential settlement success and/or postsettlement competition according to temperature conditions, favoring C. robusta during the warmer season and the native species C. intestinalis during the colder season
Summary
Coastal man-made infrastructures, such as harbors, marinas, or aquaculture facilities, are growing in number and in size and are modifying marine coastal landscapes at an unprecedented rate around the world (Airoldi & Beck, 2007; Bulleri & Chapman, 2010). The two species are important members of fouling communities and well established in artificial habitats including marinas and harbors worldwide (Aldred & Clare, 2014; Bouchemousse, Lévêque, Dubois, & Viard, 2016; Lambert & Lambert, 1998; Ramsay, Davidson, Landry, & Arsenault, 2008; Tracy & Reyns, 2014) They live in syntopy in several marinas in the western English Channel and southern Brittany in the Northeast Atlantic (Bouchemousse, Lévêque, et al, 2016; Nydam & Harrison, 2011). We showed a very low relative abundance of C. robusta in spring compared with autumn This variation can be attributed to differential settlement success and/or postsettlement competition according to temperature conditions, favoring C. robusta during the warmer season and the native species C. intestinalis during the colder season. Species-diagnostic molecular markers were used to reliably identify species at the juvenile stage
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
