A Comparison Among Assemblages in Areas Invaded byCaulerpa taxifoliaandC. racemosaon a Subtidal Mediterranean Rocky Bottom

Abstract

This study compares the structure of Mediterranean macroalgal assemblages invaded by Caulerpa taxifolia and C. racemosa. Assemblages in areas colonized by the two algae and in reference areas were sampled and analyzed for 2 years. Significant differences were recorded both between reference and invaded areas and between areas invaded by different Caulerpa species. Macroalgal assemblages colonized by C. racemosa were more separated from references than those colonized by C. taxifolia. Differences between assemblages colonized by C. racemosa and the others decreased during the alga's period of vegetative rest and increased at the last sampling date. While erect and turf species showed similar patterns in invaded areas, covers of encrusting algae were lower in C. racemosa areas than in C. taxifolia areas.

Under the canopy: Community-wide effects of invasive algae in Marine Protected Areas revealed by metabarcoding

“…Studies to date have shown their effect on native macroflora and macrofauna (e.g., Piazzi et al, 2001;Balata et al, 2004;Cebrian et al, 2012;Deudero et al, 2010;Marbà et al, 2014) in terms of compositional changes and/or abundance shifts. However, they also have more cryptic impacts.…”

“…Another side of invasion biology is the assessment of the impact of alien species on native assemblages. This is usually performed by traditional community analysis methods, involving sampling, sorting, identification, and preparation of qualitative and/or quantitative inventories (e.g., Piazzi et al, 2001;Balata et al, 2004;Box et al, 2010). These tasks are time-consuming, strongly dependent on available taxonomic expertise, and in practice applied only to the analysis of the larger elements of the fauna and flora which constitute only a minor fraction of the diversity present (Blaxter, 2016).…”

Changes in seagrass polychaete assemblages after invasion by <i>Caulerpa racemosa</i> var. <i>cylindracea</i> (Chlorophyta: Caulerpales): community structure, trophic guilds and taxonomic distinctness

“…Thus, we postulated that the increasing spatial complexity provided by a high biomass of their stolons and fronds (Longepierre et al, 2005) growing over the dead seagrass mat layer, increased the complexity of the habitat and enhanced the structuring of the polychaete assemblage. During summer and autumn, the invasive algae grew quickly and formed extensive mats of stolons, which trapped sediments to the extreme that the lower vegetation layers may be affected (Balata et al, 2004). The stolon/frond network was less complex in winter and spring and, correspondingly, low polychaete densities and diversities were found.…”

“…Invaders could be highly competitive and their interaction with native species may cause a global decrease in biodiversity (Bax et al, 2003). Negative effects of invasive species on the local biota have been recently reported, especially for macroalgal communities Meinesz et al, 2001;Balata et al, 2004;Meinesz, 2004). In the Mediterranean Sea, 84 introduced macrophytes have been reported to date (Boudouresque and Verlaque, 2002), and two of them belong to the green algae genus Caulerpa: C. taxifolia and C. racemosa (Ceccherelli and Sechi, 2002).…”

Photosynthesis and daily metabolic carbon balance of the invasive <i>Caulerpa racemosa</i> var. <i>cylindracea</i> (Chlorophyta: Caulerpales) along a depth gradient

“…cylindracea (hereafter C. racemosa) has spread extensively throughout almost the whole Mediterranean coast (Verlaque et al, 2003;Piazzi et al, 2005) and has become known as one of the most notorious and aggressive invaders of recent decades (Streftaris and Zenetos, 2006). In the colonized sites the alga is able to develop high biomasses over different substrate types, constraining the diversity of native benthic assemblages (Argyrou et al, 1999;Piazzi et al, 2001;Balata et al, 2004;Piazzi and Balatta, 2008;Vázquez-Luis et al, 2008;Klein and Verlaque, 2009).…”