Phenological and molecular studies on the introduced seaweed Dictyota cyanoloma (Dictyotales, Phaeophyceae) along the Mediterranean coast of the Iberian Peninsula

Abstract

Dictyota cyanoloma, a distinctive brown algal species characterized by a blue-iridescent margin, was recently reported as an introduced species in the Mediterranean Sea (Steen et al., 2016) but little is known about its distribution dynamics, morphological plasticity and genetic structure. In the present integrative study, we evaluate its past and present occurrence along the Mediterranean Iberian coast, assess the species’ phenology in Palamós (Girona, Spain) and analyze the haplotype diversity by sequencing 49 individuals from nine sampling sites for different chloroplast and mitochondrial DNA regions. Although D. cyanoloma currently occurs along the Mediterranean Iberian coast (in 19 of 36 localities sampled between Algeciras and Llançà, mostly in marinas and harbour environments), we were not able to find any herbarium material of this species (at BCN-Phyc and MA) predating the year 1987. In Palamós, D. cyanoloma is present all through the year, with a maximum development in winter and a minimum in summer. Fertile specimens are absent during summer (July and August). Sporophytes are dominant from January to June and dioecious gametophytes were found only in February, March and June. Information about the antheridia, which has never been described before, is provided. Two chloroplast and three mitochondrial haplotypes were observed, indicating that multiple introductions of D. cyanoloma occurred in the study area. Additionally, the genetic structure suggests that spread did not occur through simple advancing wave fronts but by several long-distance dispersal events. Further studies employing microsatellite markers could potentially offer a better resolution to unravel expansion and colonisation dynamics of D. cyanoloma in the Mediterranean Sea.

Uncertainties and validation of alien species catalogues: The Mediterranean as an example

“…Annex 1 includes 72 established aliens in the Mediterranean that are missing in Galil et al (2016). Among the taxa, most of the macroalgae are included in the recent CIESM atlas (Verlaque et al, 2015), while 4 species, namely Monosporus indicus Børgesen, Dictyota cyanoloma Tronholm, De Clerck, Gomez Garreta & Rull Lluch, Cutleria multifida (Turner) Greville and Halimeda incrassata (J. Ellis) J. V. Lamouroux were reported in 2016 (Hoffman and Wynne, 2016;Aragay et al, 2016;Kawai et al, 2016;Alos et al, 2016). Previously considered as debatable (Verlaque et al, 2015), the introduction of the Red Sea species Palisada mariserubri (K.W.…”

Native, invasive and cryptogenic Ulva species from the Israeli Mediterranean Sea: risk and potential

“…These decades have been a time of rapid environmental change in Israel, particularly rising sea temperatures (Gertman et al, 2013;Shaltout & Omstedt, 2014;Raveh et al, 2015;Ozer et al, 2016) combined with local effects of power and desalination plants (Titelboim et al, 2016). Also, new aliens are reported from the Mediterranean with increasing frequency (Flagella et al, 2009;Wolf et al, 2012;Katsanevakis & Crocetta, 2014;Aragay et al, 2016). More than 115 introduced benthic algae and seagrass taxa have been recorded in the Mediterranean (Mineur et al, 2015), mainly transferred through the Suez Canal (known as "Lessepsian invaders"; Katsanevakis & Crocetta, 2014), with ballast water, water currents and other organisms identified as vectors of transportation.…”

Sighting of Saccorhiza polyschides (Lightfoot) Batters (Phaeophyceae, Stramenopiles) in Algeria (Mediterranean Sea): an Insight into Range Expansion Routes

“…López-Legentil et al (2015), Boudouresque & Sempéré (2017), Petrocelli et al (2018, Verlaque & Breton (2019). on the basis of genetic tools, the expansion of Dictyota cyanoloma tronholm, de clerck, A. Gomez-Garetta & rull Lluch (Phaeophyceae), native to Australia, along the Mediterranean coasts, has been shown to match both the saltation (from harbour to harbour) and the diffusion models (Aragay et al 2016); and 3) range expansion events can prove to be highly uncommon. despite the major current of Atlantic water which enters the Mediterranean at Gibraltar and runs eastwards along the north African coast, only a handful of colonization events have been recorded in more than two centuries.…”