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and 6. Dictyota cyanoloma. Fig. 5. Dictyota cyanoloma clearly showing its characteristic blue iridescent margin, photograph taken by Joana Aragay, port of Almeria, 2013. Fig. 6. Boat hull fouled by Dictyota cyanoloma, photograph taken by Olivier De Clerck at Garachico Bay, Tenerife, 2014. 

and 6. Dictyota cyanoloma. Fig. 5. Dictyota cyanoloma clearly showing its characteristic blue iridescent margin, photograph taken by Joana Aragay, port of Almeria, 2013. Fig. 6. Boat hull fouled by Dictyota cyanoloma, photograph taken by Olivier De Clerck at Garachico Bay, Tenerife, 2014. 

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ABSTRACTDictyota cyanoloma has recently been described from the Mediterranean Sea and Macaronesia but doubt had arisen as to whether this species was truly native in Europe. The species is mainly found on non-natural substrata (harbour walls, marinas, boat hulls, etc.), strongly suggesting that it is an introduction. Molecular sequence information...

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... Europe, D. cyanoloma is thriving in non- natural environments such as ports, marinas and yacht- ing clubs (Table 1, Fig. 5), and artificial substrata such as pontoons, jetties and neglected ship hulls are often fouled by the species (Fig. 6). Along the Iberian Peninsula and the NW Moroccan coast, some natural habitats harbour populations of the species. In compar- ison sampling localities within Australia are almost strictly natural environments. This observation is con- current with the idea of Europe being the introduced range, as marine invaders are often growing on artificial ...

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... The global transfer of marine species by human-mediated means is of significant concern for biodiversity conservation and the sustainable development of coastal and oceanic resources [1]. Some introduced species can become invasive, and their impacts on local ecosystems might be devastating [2]. Introduced species from all major animal, plants and alga phyla have been detected around the globe [1]. ...
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We report for the first time the occurrence of the Japanese kelp Saccharina japonica on the Pacific coast of southern Chile following an illegal introduction for aquaculture purposes. In November 2020, a citizen complaint indicated that the non-native kelp was being illegally farmed in Canal Caicaén. Specimens of the non-native kelp were collected during successive surveys for molecular and morphological analyses, and reproductive viability tests. The species was determined using two mitochondrial molecular markers, COI and trnW-L. Phylogenetic analysis confirmed the taxonomic identity of the specimen as S. japonica and revealed a genetic similarity with S. japonica × S. latissima hybrid cultivars Sanhai and Rongfu. In April 2021, several adult specimens became fertile at the farm site and the laboratory and released meiospores were able to develop into embryos after 15–20 days of incubation. These findings underline the risk for this kelp to disperse and colonize in the natural surrounding habitat, with potential impacts on local coastal ecosystems.
... There are possible indications of other cryptic invasive species that need further morphological and genetic analysis for identification. The local conditions favour the growth of highly adaptive species such as the native Padina pavonica (Linnaeus) Thivy, 1960 (see Celis-Plá et al., 2015) and the Australian alien Dictyota cyanoloma Tronholm et al., 2010, (Steen et al. 2017. ...
... It has been found in European waters (United Kingdom, Azores, Madeira, Canary Islands, Portugal, Morocco, Iberian Peninsula, Balearic Islands, Croatia, Greece and Turkey) and in Australia and New Zealand (Guiry & Guiry, 2021). In an attempt to explain the disjoint distribution range of this species between European waters (Northern Hemisphere) and Australian and New Zealand coasts (Southern Hemisphere) and to discover the true origin of the species, Steen et al. (2017) carried out a phylogenetic analysis of specimens from both geographical areas and compared their affinities to other Australian species of the genus Dictyota. They concluded that from a genetic point of view D. cyanoloma has more affinity with Australian species than with those of European waters. ...
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The Mediterranean Sea is a hotspot for biodiversity and endemic species (between 4 % and 18 % of known species are endemic, depending on the group), but this environment, favourable for native species, also favours exotic species. To ascertain how biodiversity has been impacted by intense human activity, we surveyed the marine life in the Barcelona Forum bathing area, an artificial beach receiving large amounts of waste from neighbouring areas and effluent from the nearby sewage treatment plant. Despite such eutrophic influences and the replacement of natural substrates with artificial ones, a surprisingly rich marine biota of 514 species was found. The groups with most species identified were molluscs (176), fish (88), crustaceans (65) and algae (50). These results include 15 exotic species that have settled in this ecosystem, such as the sea hare Bursatella leachii and the polychaete Branchiomma luctuosum, and some iconic natives such as the Fan mussel (Pinna nobilis) and the Dusky grouper (Epinephelus marginatus). Urban litter was sampled and no significant deleterious effects on the biota were detected. The site acts as a refuge for fish and is conducive to the settlement of encrusting species that colonize new substrates.
... Sporadic monitoring and surveillance, weak taxonomic knowledge, or elusive behavior of some species have left several marine invasions undetected for years, decades or even centuries (Carlton, 2009;Griffiths et al., 2010;Zenetos et al., 2019). Several approaches have been attempted to reconstruct the timing of first introduction events and subsequent stages of invasion: reexamination of old museum or herbarium collections (Ahnelt, 2016;Steen et al., 2017), analysis of published descriptions (Zullo, 1992;Galil et al., 2018), interviews to local fishermen (Bariche et al., 2014;Azzurro et al., 2019), molecular tools (Ordóñez et al., 2016;Deldicq et al., 2019) and radiometric dating (Petersen et al., 1992;Albano et al., 2018). In spite of different approaches utilized, the gap still persists because long and continuous timeseries are difficult to obtain, due to the often sporadic and intermittent availability of marine biodiversity data; hence several studies are restricted to inter-decadal comparisons (Parravicini et al., 2015) or are based on population model simulations (Clark et al., 2013;Walsh et al., 2016). ...
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Invasive alien species threaten biodiversity and ecosystem structure and functioning, but incomplete assessments of their origins and temporal trends impair our ability to understand the relative importance of different factors driving invasion success. Continuous time-series are needed to assess invasion dynamics, but such data are usually difficult to obtain, especially in the case of small-sized taxa that may remain undetected for several decades. In this study, we show how micropaleontologic analysis of sedimentary cores coupled with radiometric dating can be used to date the first arrival and to reconstruct temporal trends of foraminiferal species, focusing on the alien Amphistegina lobifera and its cryptogenic congener A. lessonii in the Maltese Islands. Our results show that the two species had reached the Central Mediterranean Sea several decades earlier than reported in the literature, with considerable implications for all previous hypotheses of their spreading patterns and rates. By relating the population dynamics of the two foraminifera with trends in sea surface temperature, we document a strong relationship between sea warming and population outbreaks of both species. We conclude that the micropaleontologic approach is a reliable procedure for reconstructing the bioinvasion dynamics of taxa having mineralized remains, and can be added to the toolkit for studying invasions.
... Alongside with shipping and aquaculture, recent international studies indicate that recreational marinas are important hubs for new species introduction and secondary spreading events (Clarke-Murray et al., 2011;Ashton et al., 2014;Ulman et al., 2017;Pelletier-Rousseau et al., 2019;Martínez-Laiz et al., 2019). Furthermore, several recent records of marine NIS in the Mediterranean Sea come from marina habitats (Ros et al., 2013;Marchini et al., 2015;Marić et al., 2016;Ferrario et al., 2017;Steen et al., 2017), suggesting that marinas are part of the stepping-stone invasion process. The result of this continuous movement of marine species across geographical areas, a phenomenon called 'biological invasions' is not only dramatically altering the natural distribution of marine species, with effects on native biodiversity, * Corresponding author. ...
Article
Most of marine non-indigenous species still suffers of large gaps in knowledge even regarding the most basic life history traits. The present study aims to understand the biology and ecology of the pacific isopod Paranthura japonica in a newly invaded site in the Central Mediterranean Sea, specifically focusing on its population dynamics in response to seasonal variation of environmental parameters. To collect standardised samples of this minute benthic species with cryptic behaviour, we use nylon bath sponges as Artificial Substrate Units, and an image analysis software for digital measurements of total body length. We conclude that P. japonica, native to the cold Okhotsk sea, has well adapted to the warmer Mediterranean conditions. Its population has been found well-established and persistent throughout the year, while its numeric positive response to increasing temperature was one of our most surprising findings. In fact, reproductive events occur throughout the year, but peak during summer months. Finally, we show that nylon bath sponges represent an efficient artificial substrate for obtaining quantitative samples of peracarid crustaceans.
... When subsequent collections revealed that the species was also found along the Australian coastline from New South Wales to Western Australia, questions regarding the connectivity and possibilities of introduction arose. Subsequent phylogenetic analyses positioned D. cyanoloma within a clade containing almost exclusively species native to Australia (e.g., D. alternifida, D. diemensis, and D. intermedia), lending an evidence to a non-native origin of D. cyanoloma in Europe (Aragay et al. 2016, Steen et al. 2017). In addition, Steen et al. (2017) demonstrated that populations of D. cyanoloma in Europe feature less genetic diversity compared with Australian populations, which is possibly due to a founder effect occurring in an introduced population with low number of initial colonists (Barrett and Kohn 1991). ...
... Subsequent phylogenetic analyses positioned D. cyanoloma within a clade containing almost exclusively species native to Australia (e.g., D. alternifida, D. diemensis, and D. intermedia), lending an evidence to a non-native origin of D. cyanoloma in Europe (Aragay et al. 2016, Steen et al. 2017). In addition, Steen et al. (2017) demonstrated that populations of D. cyanoloma in Europe feature less genetic diversity compared with Australian populations, which is possibly due to a founder effect occurring in an introduced population with low number of initial colonists (Barrett and Kohn 1991). Furthermore, D. cyanoloma in Europe predominantly occurs in artificial habitats such as marinas and harbors (Rull Lluch et al. 2007), providing additional evidence that it was introduced. ...
... Most of the samples from California were nested in a cluster of populations from Morocco, Spain, and Portugal. Among European populations, we observed high levels of genetic variation and differentiation, further supporting the likelihood of a complicated introduction history of D. cyanoloma in Europe (Steen et al. 2017). Likewise, the introduction history of this species in California is difficult to elucidate because the link with the Australian source populations was not clear. ...
Article
Here we report for the first time the presence of Dictyota cyanoloma in southern California. Dictyota cyanoloma is conspicuous in harbors and bays by its distinctive bright blue‐iridescent margins. This species was originally described from Europe but subsequent studies have revealed that it represented an introduction from Australia. The current distribution of D. cyanoloma comprises southern Australia and the North East Atlantic, including the Mediterranean Sea and the Macaronesian islands. The presence of D. cyanoloma in southern California is supported by molecular cox1 and psbA gene sequences. A reconstruction of the invasive history based on nine polymorphic microsatellite markers reveals a close affinity of the Californian specimens with European populations. Dictyota cyanoloma in the United States appears to be (so far) restricted to the Californian coast from San Diego Bay in the south to Santa Catalina Island and Long Beach Harbor in the north. A correlative species distribution model suggests gradually declining habitat suitability north of the Southern Californian Bight and high suitability in Baja California, including the Gulf of California. Finally, its widespread abundance in bays and harbors suggests shipping is a likely transport mechanism.
... Historic collections have played a very important role in tracing the introduction of Dictyota cyanoloma (Dictyotales) into the Mediterranean [55]. Dictyota cyanoloma was described in 2010, based on specimens from Palamós, NW Mediterranean [56], although the species was first reported from the Iberian Peninsula as D. ciliolata by Rull Lluch et al. [57]. ...
... Dictyota cyanoloma was described in 2010, based on specimens from Palamós, NW Mediterranean [56], although the species was first reported from the Iberian Peninsula as D. ciliolata by Rull Lluch et al. [57]. The species is widely distributed in the Mediterranean Sea and recent records have proven its expansion to the European Atlantic (Portugal, Galicia, the SW England), and the Macaronesia [56,[58][59][60][61][62][63], while Steen et al. [55] reported it from Australia and New Zealand. Steen et al. [55] obtained molecular sequence information from historical herbarium samples of Dictyota spp. ...
... The species is widely distributed in the Mediterranean Sea and recent records have proven its expansion to the European Atlantic (Portugal, Galicia, the SW England), and the Macaronesia [56,[58][59][60][61][62][63], while Steen et al. [55] reported it from Australia and New Zealand. Steen et al. [55] obtained molecular sequence information from historical herbarium samples of Dictyota spp. which proved the presence of D. cyanoloma in the Adriatic Sea as early as 1935. ...
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The Mediterranean Sea is currently experiencing a decline in the abundance of several key species, as a consequence of anthropogenic pressures (e.g., increase in human population, habitat modification and loss, pollution, coastal urbanization, overexploitation, introduction of non-indigenous species and climate change). Herbaria and natural history collections are certainly fundamental for taxonomic studies, but they are also an invaluable, if currently underestimated, resource for understanding ecological and evolutionary responses of species to environmental changes. Macroalgae herbarium collections, which are really consistent (ranging from 200,000 to approximately 500,000 specimens) in some European herbaria (e.g., Muséum National d’Histoire Naturelle in Paris, University of Copenhagen, Natural History Museum in Kensington), can be successfully used as real “witnesses” to biodiversity changes. In this respect, we report some case studies from the Mediterranean Sea which summarize well the potential of macroalgae herbarium specimens to provide useful data on biodiversity changes. Indeed, these data enable the evaluation of the responses of biota, including shifts in species ranges, the detection of the presence of introduced species, and the prediction of changes in species distributions and patterns under future climate scenarios. To increase the use of this invaluable tool of research, their curation, the digitization of collections, and specimen genomics should be even more addressed.
... As a result, overlooked and cryptic introductions are common, and the real number of introductions is probably being underestimated (Carlton and Geller 1993). Moreover, cryptogenic species, whose native or introduced nature cannot be determined with certainty, abound among macroalgae (Díaz-Tapia et al. 2017a;Steen et al. 2017). The family Rhodomelaceae and particularly its tribes Polysiphonieae and Streblocladieae (formerly Polysiphonia sensu lato) are commonly listed as introduced or cryptogenic seaweed species worldwide Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10811-019-01932-4) ...
... The use of molecular approaches can contribute to the detection of new non-native species in such problematic taxa, and it has been proven useful for detecting seaweed cryptic introductions and determining their distributions (e.g. Zuccarello et al. 2002;Díaz-Tapia et al. 2013, 2017aSteen et al. 2017;Manghisi et al. 2019). ...
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Red algae are frequently dominant components of the non-native biotas in coastal areas. They often remain undetected because of morphological similarity between native and introduced species and cryptic diversity. Routine use of DNA barcodes can aid in setting baseline tabulations of native species and for detecting introduced species. We performed an extensive survey of the red algal family Rhodomelaceae in southern Australia, producing a dataset containing more than 1100 rbcL sequences. The objective of this study was to screen that dataset for introduced species of the tribes Polysiphoniaeae and Streblocladieae, and to provide morphological information of presumably introduced species that were not previously recorded in Australia. Molecular data and morphological observations confirmed the presence of five presumably introduced species: Leptosiphonia brodiei, Melanothamnus japonicus, M. strictissimus, Polysiphonia morrowii and P. delicata. Polysiphonia morrowii and M. strictissimus were detected for the first time in Australia, and M. japonicus and P. delicata were found to be more widely distributed than previously known. Somewhat unexpectedly, the distribution range of L. brodiei has apparently shrunk, with our survey suggesting it remains only in Tasmania. Four of these species have been reported as introduced species in other countries, but M. strictissimus is here recorded for the first time outside its native New Zealand. Although all five species can be considered introduced or cryptogenic, only P. morrowii, M. japonicus and M. strictissimus were locally abundant, and further work will be needed to assess their ability to spread and effect negative impacts on native biotas.
... Distribution ranges are inadequately characterised for many species still, but from detailed studies in Europe and the Atlantic Ocean, a pattern emerges of species with predominantly regional distributions confined to realms or provinces (sensu Spalding et al. 2007), but some species definitely have large ranges spanning more than one ocean basin (Tronholm et al. 2010(Tronholm et al. , 2012(Tronholm et al. , 2012. At least one species, D. cyanoloma has been shown to be introduced, probably from southern Australia to the Mediterranean Sea (Steen et al. 2017). ...
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The genus Dictyota (Dictyotales, Phaeophyceae) comprises parenchymatous algae occurring predominantly in tropical to warm-temperate waters and has gathered attention due to its diverse secondary metabolites with antibiofouling and pharmaceutical potential, its oil content, and its potential as animal feed. This has resulted in an increase in economic potential during the last decade. In this review, we summarise the recent knowledge on the genus and concentrate on the applications and the economic potential of Dictyota. In addition, the review summarises the taxonomy, anatomy, cytology, genetic data, life history, chemical composition, nutritional value and ecological and economic importance of Dictyota species. Currently, around 100 species are recognised together with the morphologically similar and closely related genera Dilophus, Canistrocarpus and Rugulopteryx (tribus Dictyoteae). The thallus is characterised by one or more lens-shaped apical cells that divide into cortical and medullary cell layers. Species typically grow in rocky intertidal pools and subtidal areas. Dictyota is consumed locally in the Caribbean, Malayan-Indonesian and Hawaiian regions. Extracts of Dictyota which contain active compounds, such as diterpenes and phlorotannins, have been attributed antimicrobial, health and wellness promoting effects which render them promising candidates for the design of functional foods, phytomedicinal products, and cosmetics. The high fraction of lipids and fatty acids has propelled emerging applications in the biofuel industry and as a feedstock species.
... This record suggests a contiguous, albeit rare distribution of this taxon in the shallow infralittoral from the Azores, Madeira and the Canary Islands, and throughout the Mediterranean, including the Adriatic to the Mediterranean coast of Turkey. Recent work (Steen et al. 2017) has shown that this taxon is not native to Europe, but an introduction which has been present in the Adriatic as early as 1935. The same study (Steen et al. 2017) showed that D. cyanoloma is also present in western and southern Australia. ...
... Recent work (Steen et al. 2017) has shown that this taxon is not native to Europe, but an introduction which has been present in the Adriatic as early as 1935. The same study (Steen et al. 2017) showed that D. cyanoloma is also present in western and southern Australia. ...
Article
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Parts of the macroalgal flora of the eastern Mediterranean remain incompletely known. This applies in particular to the circalittoral communities. This study, based upon 2 cruises in the Ionian and Aegean Seas, surveyed benthic communities from 40 to 150 m depth by remotely-operated vehicle (ROV) with a special focus on detecting communities of the Mediterranean deep-water kelp Laminaria rodriguezii . These were complemented by shallow-water surveys on adjacent coastlines by snorkelling and scuba diving. While no kelp could be detected at any of the sites surveyed, ROV surveys of northern Euboia Island revealed the first east Mediterranean record of Sebdenia monnardiana (Sebdeniales, Rhodophyta). Snorkelling surveys on the coast of southeast Kefalonia yielded the first record of the alien alga Dictyota cyanoloma in Greece. This paper reports rbc L and SSU sequences for Sebdenia monnardiana , and COI for Dictyota cyanoloma.
... Specimens of Dictyota were collected in the shallow subtidal zone at two localities in East Falkland ( Fig. 1 Total genomic DNA was extracted from silica gel-dried samples using a modified CTAB-extraction method (Steen et al. 2017). Sequences were generated for the plastidencoded PSII reaction centre protein D1 (psbA) and the mitochondrial-encoded cytochrome oxidase subunit 1 (cox1) gene. ...
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Surveys of the seaweed flora of the Falkland Islands and of Tierra del Fuego revealed the presence of a new species of brown alga. Dictyota falklandica sp. nov. inhabits the shallow rocky infralittoral in sheltered localities and the lower intertidal in more exposed sites. Dictyota falklandica has a regular to irregular habit of dichotomously branched blades, forming erect thalli composed of a single-layered cortex and medulla, with margins in the apical parts dotted with dormant apical cells. Sporangia occur in irregular groups or longitudinal lines on the thallus surface. Molecular phylogenies based on chloroplast psbA and rbcL and mitochondrial cox1 sequences showed that the species from the Falkland Islands is sister to a clade formed by D. korowai, recently described from New Zealand and D. kunthii known from both the Pacific coast of South America and New Zealand. Temperature tolerance experiments, showing mortality at 25 °C but survival at 20 °C, confirm the cold-temperate affinity of this taxon. Its relationship to other cold-temperate Southern Hemisphere species is discussed, with its closest relatives living in regions with sea surface temperatures of at least 7–10 °C higher.