Citizen science: a successful tool for monitoring ...

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Citizen science: a successful tool for monitoring invasive alien species (IAS) in Marine Protected Areas. The case study of the Egadi Islands MPA (Tyrrhenian Sea, Italy) Anna Maria Mannino & Paolo Balistreri To cite this article: Anna Maria Mannino & Paolo Balistreri (2018): Citizen science: a successful tool for monitoring invasive alien species (IAS) in Marine Protected Areas. The case study of the Egadi Islands MPA (Tyrrhenian Sea, Italy), Biodiversity, DOI: 10.1080/14888386.2018.1468280 To link to this article: https://doi.org/10.1080/14888386.2018.1468280

Published online: 17 May 2018.

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Biodiversity, 2018 https://doi.org/10.1080/14888386.2018.1468280

Citizen science: a successful tool for monitoring invasive alien species (IAS) in Marine Protected Areas. The case study of the Egadi Islands MPA (Tyrrhenian Sea, Italy) Anna Maria Manninoa and Paolo Balistrerib a

Department of Biological, Chemical and Pharmaceutical Sciences and Technologies, Section of Botany and Plant Ecology, University of Palermo, Palermo, Italy; bBio & Tec. Soc. Cop., Trapani, Italy

ABSTRACT

The chief purpose of Marine Protected Areas (MPAs) is biodiversity conservation. The effects that invasive alien species (IAS) have on MPAs, and vice versa, are not yet fully known, even though assessing them is crucial for MPA planning. Management plans require sound knowledge of the pathways of introduction, the impact and current distribution of IAS. Monitoring plans are essential for preventing and reducing the risk of IAS introduction. In this respect, the involvement of citizen scientists in gathering data (validated by taxonomic experts) on the occurrence of IAS, that would otherwise be impossible to collect, may be crucial. We report on our experience of citizen science in the Egadi Islands MPA with the project ‘Caulerpa cylindracea – Egadi Islands’, aimed at monitoring the spread dynamics of the ‘sea grape’ C. cylindracea. The project registered 156 sightings and also allowed collection of records and information concerning other non-indigenous and cryptogenic species, e.g. the spotted sea hare (Aplysia dactylomela), the harpoon weed (Asparagopsis armata), the red sea plume (Asparagopsis taxiformis), the tube-building sabellid (Branchiomma bairdi), the blue spotted cornet fish (Fistularia commersoni) and the nomad jellyfish (Rhopilema nomadica).

Introduction The introduction of non-indigenous species (NIS, i.e. organisms introduced outside of their natural, past or present, range and outside of their natural dispersal potential) has been pointed out as a major threat to biodiversity and natural ecosystem functioning (Wallentinus and Nyberg 2007; Katsanevakis et al. 2014; Vergés et al. 2016). NIS may in time become invasive (i.e. invasive alien species (IAS)) and may cause biodiversity loss and ecosystem service changes (Brunel et al. 2013; Giakoumi 2014; Vergés et al. 2014, 2016). In the Mediterranean Sea, due to multiple human-borne stressors, the number of recorded NIS has been increasing exponentially in the last 100 years (Occhipinti-Ambrogi et al. 2011a, 2011b; Katsanevakis et al. 2014), currently reaching a number around 1000 NIS, of which 134 species are macrophytes (Zenetos et al. 2012; Galil et al. 2015; Verlaque et al. 2015; Alós et al. 2016). Since IAS have been recognised as one of the major threats of marine ecosystems, several international organisation and conventions (e.g. the Convention on Biological

CONTACT Anna Maria Mannino

[email protected]

© 2018 Biodiversity Conservancy International

ARTICLE HISTORY

Received 19 April 2018 Accepted 19 April 2018 KEYWORDS

Caulerpa cylindracea; citizen science; invasive alien species; Marine Protected Areas; Mediterranean Sea; monitoring

Diversity, the Ramsar Convention, the International Union for Conservation of Nature, the Water Framework Directive, the Barcelona Convention) recognised the importance of IAS impacts on biodiversity and recommend that contracting parties should take measures to prevent the introduction of IAS and attempt to limit their spread and their impact (e.g. see Monaco and Genovesi 2014). Sicily and its surrounding islands, also including a high number of Marine Protected Area (MPAs), as a consequence of their geographic position and the intense maritime traffic volumes, including fisheries and recreational fleets (Occhipinti-Ambrogi et al. 2011a, 2011b; Katsanevakis et al. 2014) that foster the introduction of marine alien species, is a region particularly vulnerable and prone to NIS invasions (Bianchi 2007; OcchipintiAmbrogi et al. 2011a, 2011b; Katsanevakis et al. 2012, 2014). This area also plays an important role as recipient area, transit zone and source for secondary dispersal, highlighting the key role it can play in the circulation of NIS within the Mediterranean Sea.

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A. M. MANNINO AND P. BALISTRERI

Since frontiers do not exist in the sea, biological invasions may severely affect MPAs, whose major aim is biodiversity conservation, because they are also located in proximity to ports and marinas or are frequently used by small recreational or fishing boats as well as tourists. Despite the availability of a large amount of information on MPAs, the eﬀects of MPAs on IAS has been poorly studied (Burfeind et al. 2013; Ardura et al. 2016; Giakoumi et al. 2016; Giakoumi and Pey 2017). It therefore remains doubtful if MPAs are able to resist IAS, due to the high species richness conferring them an ‘invasion resistance’, or instead may favour their introduction and spread through tourism activities, which increase disturbance and vectors (boat anchors, diving, etc.) (Giakoumi and Pey 2017). To reduce the risk of future IAS introduction and to better understand their invasive potential and spread dynamics, monitoring and surveillance plans are required. The creation of permanent alarm systems and public awareness campaigns might be effective tools in the management of IAS introductions. In this regard, MPAs, where the effects of NIS invasion can be studied and management strategies can be developed, might play an important role as ‘sentinel systems’. Recently, an IAS strategy for the MedPAN Network, aiming to promote the establishment, the operation and the sustainability of a Mediterranean network of MPAs, has been developed. The strategy intends to assist MPAs for invasive species management. To plan effective management and conservation strategies, reliable data on distribution and spread dynamics of IAS are essential. Since intensive monitoring programs could be very expensive, citizen science, involving citizens (e.g. tourists, fishermen, divers) in the collection of data, could be a useful tool for providing data on IAS that would otherwise be impossible to collect because of limitations on time and resources. Of course, all these data are reliable only if they are scientifically validated. The number of citizen science projects (e.g. ‘Seawatchers’, available at http://www.observadoresdelmar.es/?idioma=en, ‘Aliens in the sea’ available at the Facebook page: Progetto ‘Aliens in the sea’, ‘Spot the Alien Fish’, available at https://www.facebook.com/aliensmalta, and MedMIS, a new IUCN app for marine invasive species in Mediterranean MPAs) has rapidly and enormously increased in recent years (Conrad and Hilchey 2011), thanks also to the wide availability of mobile technologies and internet access that enable an easy and cheap way to communicate, share and interchange data. Currently, citizen science has been widely recognised as an effective tool to expand the scale of NIS data collection and monitoring. Among IAS, Caulerpa cylindracea Sonder, introduced from Australia and New Caledonia (Belton et al. 2014), has raised serious concern due to its ascertained impact on

Mediterranean communities (Boudouresque et al. 1995; Klein and Verlaque 2008; Papini, Mosti, and Santosuosso 2013; Katsanevakis et al. 2014). This species, first recorded in Italy in 1993 at Baia di San Panagia (Sicily) and at the Island of Lampedusa (Alongi et al. 1993), is currently present around almost all the Mediterranean Sea. We report our experience of citizen science in the Egadi Islands MPA with the project ‘Caulerpa cylindracea – Egadi Islands’, aimed at monitoring the spread dynamics of C. cylindracea within the Egadi Islands MPA.

Material and methods The Egadi Islands MPA (Aegadian archipelago), instituted in 1991, is the largest Italian MPA. This small archipelago, located approximately 7–9 km from the western coast of Sicily (Italy, Tyrrhenian Sea), is composed of three main islands (Favignana 37°56′00′′ N, 12°19′00′′ E; Marettimo 37°58′00′′ N, 12°03′00′′ E; Levanzo 38°00′00′′ N, 12°20′00′′ E) and a few small islets (Galeotta 37°54′43′′ N, 12°17′55′′ E; Galera 37°54′51′′ N, 12°17′24′′ E; Preveto 37°54′51.68′′ N, 12°18′7.57′′ E; Formica 37°59′21′′ N, 12°25′31′′ E; Maraone 37°59′23′′ N, 12°24′51′′ E) (Figure 1). The project ‘Caulerpa cylindracea – Egadi Islands’, addressed to different groups of volunteers (students, tourists, divers, underwater photographers, amateurs and fishermen), was based on the collection of data (place, date, depth, substrate coverage %) and photos concerning the occurrence of C. cylindracea within the MPA. Only data validated by the scientific team of the project were gathered in the database.

Results and discussion The project was presented during the International Congress GeoSub2016 (Mannino, Donati, and Balistreri 2016). The Facebook page of the project registered numerous followers (3000 only in the last month). In all we gathered 156 sightings mainly recorded by citizens (Figure 2). The alga was reported from all the three main islands even though the majority of the records were from Favignana (Figure 1). It was found in different habitats, between 0 and 40 m depth, mainly on rock, rock with sediment and sand (Figures 3 and 4). Useful information on the behaviour strategies of the alga was also gathered, e.g. the ability of the stolons to create bridges in order to reach new areas for the anchorage and the strength of the anchorage due to the high number of rhizoids (Figure 4(d)). These strategies allow C. cylindracea to spread rapidly, forming compact multi-layered mats able to trap the sediment that negatively affect the native macroalgal assemblages (Klein and Verlaque 2008; Holmer et al. 2009; Matijević et al. 2013). A low diversity was observed in areas colonised by

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Figure 1. Occurrences of C. cylindracea within the Egadi Islands MPA.

Figure 2. Numbers of records from the different groups of volunteers.

Figure 3. Numbers of records in the different substrate typologies.

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Figure 4. C. cylindracea stolon (a), area colonised by C. cylindracea (b), C. cylindracea intermingled with other algae (c) and a bridge created by the stolons of C. cylindracea (d).

C. cylindracea, with a number of macroalgal species ranging from 8 to 12. Moreover, it seems that C. cylindracea takes advantage when native communities are suffering. A relationship between frond length and substrate typology was also observed with longer fronds observed on sand substrates. Since higher coverage values were observed in areas where the anchorage of boats is permitted, we hypothesise that the anchorage activities, mostly carried out by pleasure boats, may also favour the spread of C. cylindracea. Even though the project ended in 2016, we are still receiving a huge quantity of records, photos and information on this IAS. During the project we also received records and information concerning other NIS and cryptogenic species (see Carlton 1996; species that cannot be classifed with confdence among native nor among introduced ones) such as the ‘spotted sea hare’ Aplysia dactylomela (Rang, 1828), the ‘harpoon weed’ Asparagopsis armata (Harvey, 1855), ‘the red sea plume’ A. taxiformis ((Delile) Trevisan de Saint-Léon, 1845), the tube-building sabellid Branchiomma bairdi (McIntosh, 1885), the ‘blue spotted cornet fish’ Fistularia commersoni (Rüppel, 1838) and the ‘nomad jellyfish’ Rhopilema nomadica (Galil, Spannier & Ferguson, 1990) (Figure 5). It has been observed that the increase of sedimentation among the stolons of C. cylindracea, also favoured the settlement of the biofouler worm Branchiomma bairdi.

Currently, 16 NIS and three cryptogenic species have been recorded till now, and maritime traffic has certainly spearheaded their introduction and spread (Mannino, Balistreri, and Yokeş 2014; Mytilineou et al. 2016; Balistreri et al. 2017; Mannino and Balistreri 2017; Mannino et al. 2017). The presence of NIS in the Egadi Islands MPA, but also in other MPAs (e.g. Cecere, Petrocelli, and Saracino 2005) confirms that MPAs, despite their recognised role as promising management tool for protection of local biodiversity, are not immune from NIS invasions. However, NIS have been largely disregarded in marine conservation plans (Giakoumi et al. 2016). The expansion of NIS by recreational vessels represents an actual risk for MPAs, which are popular tourist destinations. In agreement with Evans, Barbara, and Schembri (2015) and Schembri et al. (2015), we posit that the regular and heavy maritime traffic between Sicily and the Egadi Islands MPA, particularly Favignana, may have contributed to the arrival of sessile taxa often recorded in fouling communities. Therefore, Sicily and the surrounding islands may represent an important center of secondary dispersal for the Egadi Islands MPA. NIS and cryptogenic species are likely to continue to expand, and further arrivals are to be expected. For this reason, in areas more vulnerable to marine biological invasions, like Sicily and its MPAs, regular monitoring and surveillance programs are strongly needed in order

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Figure 5. Asparagopsis taxiformis (a), A. armata (b), Aplysia dactylomela (c) and Branchiomma bairdi (d).

to manage continuous spillover effects (see also Otero et al. 2013). Indeed, this area, due to its crucial position within the Mediterranean Sea, could be an important transboundary station for monitoring the entry and spread of marine alien species, as solicited in Azzurro et al. (2014). Therefore, MPAs can play a crucial role in the struggle against invasions, by improving IAS management, monitoring the spread dynamics, raising awareness and concern of citizens of biological invasions through information but also through their involvement in activities related to the monitoring of IAS, which may help to avoid or limit the introduction of NIS and control the spread of existing ones (e.g. see Monaco and Genovesi 2014). Citizen science activities, as also highlighted by the results of this project, could significantly improve the efficacy of monitoring and surveillance plans. Moreover, data collected with the help of citizens may contribute to develop suitable management programs within the MPA such as a) the regulation of the activities (e.g. anchorage, mooring, diving and maritime traffic), b) the promotion of public awareness campaigns and training on the biological invasions phenomenon and c) the planning of regular monitoring programs. In spite of their fundamental role in conservation of marine biodiversity, MPAs have been widely demonstrated to be ineffective in stopping local introductions. Therefore, an IAS strategy integrated into the management

plan, considering the creation of permanent observatories to early detect new introductions and to assess NIS spread dynamics, the main pathways and the vectors of introduction, may be highly desirable.

Disclosure statement No potential conflict of interest was reported by the authors.

References Alongi, G., M. Cormaci, G. Furnari, and G. Giaccone. 1993. “Prima Segnalazione di Caulerpa racemosa (Chlorophyceae, Caulerpales) per le Coste Italiane.” Bollettino Accademia Gioenia Scienze Naturali Catania 26 (342): 9–53. Alós, J., F. Tomas, J. Terrados, H. Verbruggen, and E. Ballesteros. 2016. “Fast-Spreading Green Beds of Recently Introduced Halimeda incrassata Invade Mallorca Island (NW Mediterranean Sea).” Marine Ecology Progress Series 558: 153–158. Ardura, A., F. Juanes, S. Planes, and E. Garcia-Vazquez. 2016. “Rate of Biological Invasions is Lower in Coastal Marine Protected Areas.” Scientific Report 6: 33013. doi:10.1038/ srep33013. Azzurro, E., J. Ben Souissi, W. Boughedir, L. Castriota, A. Deidun, M. Falautano, R. Ghanem, M. Zammit-Mangion, and F. Andaloro. 2014. “The Sicily Strait: a Transnational Observatory for Monitoring the Advance of Non Indigenous Species.” Biologia Marina Mediterranea 21: 105–106. Balistreri, P., A. Spiga, A. Deidun, S. Km Gueroun, and M. N. D. Yahia. 2017. “Further Spread of the Venomous

6


Jellyfish Rhopilema nomadica Galil, Spannier & Ferguson, 1990 (Rhizostomeae, Rhizostomatidae) in the Western Mediterranean.” BioInvasions Records 6 (1): 19–24. Belton, G. S., W. F. Prud’homme van Reine, J. M. Huisman, S. G. A. Draisma, and C. F. D. Gurgel. 2014. “Resolving Phenotypic Plasticity and Species Designation in the Morphologically Challenging Caulerpa racemosa–peltata Complex (Chlorophyta, Caulerpaceae).” Journal of Phycology 50: 32–54. Bianchi, C. N. 2007. “Biodiversity Issues for the Forthcoming Tropical Mediterranean Sea.” Hydrobiology 580: 7–21. Boudouresque, C. F., A. Meinesz, M. A. Ribera, and E. Ballesteros. 1995. “Spread of the Green Alga Caulerpa taxifolia (Caulerpales, Chlorophyta) in the Mediterranean: Possible Consequences of a Major Ecological Event.” Scientia Marina 59: 21–29. Brunel, S., E. Fernández-Galiano, P. Genovesi, V. H. Heywood, C. Kueffer, and D. M. Richardson. 2013. “Invasive Alien Species: A Growing but Neglected Threat?” In Late Lessons from Early Warning: Science, Precaution, Innovation. Lessons for Preventing Harm. EEA Report 1/2013, Copenhagen, p. 518–540. Burfeind, D. D., K. A. Pitt, R. M. Connolly, and J. E. Byers. 2013. “Performance of Invasive Species within Marine Reserves.” Biological Invasions 15: 17–28. Carlton, J. T. 1996. “Biological Invasions and Cryptogenic Species.” Ecology 77 (6): 1653–1655. Cecere, E., A. Petrocelli, and O. D. Saracino. 2005. “Biodiversity of Phytobenthic Communities in the Marine Reserve of Porto Cesareo.” Biologia Marina Mediterranea 12 (1): 78–87. Conrad, C. C., and K. G. Hilchey. 2011. “A Review of Citizen Science and Community-Based Environmental Monitoring: Issues and Opportunities.” Environmental Monitoring and Assessment 176: 273–291. Evans, J., J. Barbara, and P. J. Schembri. 2015. “Updated Review of Marine Alien Species and Other ‘Newcomers’ Recorded from the Maltese Islands (Central Mediterranean).” Mediterranean Marine Science 16 (1): 225–244. Galil, B., F. Boero, S. Fraschetti, S. Piraino, M. Campbell, C. Hewitt, et al. 2015. “The Enlargement of the Suez Canal and Introduction of Non-Indigenous Species to the Mediterranean Sea.” Limnology and Oceanography Bulletin 24: 25–64. Giakoumi, S. 2014. “Distribution Patterns of the Invasive Herbivore Siganus luridus (Rüppell, 1829) and its Relation to Native Benthic Communities in the Central Aegean Sea, Northeastern Mediterranean.” Marine Ecology 35: 96–105. Giakoumi, S., and A. Pey. 2017. “Assessing the Effects of Marine Protected Areas on Biological Invasions: A Global Review.” Frontiers in Marine Science 4: 49. doi:10.3389/ fmars.2017.00049. Giakoumi, S., F. Guilhaumon, S. Kark, A. Terlizzi, J. Claudet, S. Felline, et al. 2016. “Space Invaders; Biological Invasions in Marine Conservation Planning.” Diversity and Distribution 22: 1220–1231. Holmer, M., N. Marbà, M. Lamote, and C. M. Duarte. 2009. “Deterioration of Sediment Quality in Seagrass Meadows (Posidonia oceanica) Invaded by Macroalgae (Caulerpa sp.).” Estuaries and Coasts 32: 456–466. Katsanevakis, S., K. Bogucarskis, F. Gatto, J. Vandekerkhove, I. Deriu, and A. C. Cardoso. 2012. “Building the European Alien Species Information Network (EASIN): a Novel

Approach for the Exploration of Distributed Alien Species Data.” BioInvasions Records 1: 235–245. Katsanevakis, S., M. Coll, C. Piroddi, J. Steenbeek, F. Ben Rais Lasram, A. Zenetos, and A. C. Cardoso. 2014. “Invading the Mediterranean Sea: Biodiversity Patterns Shaped by Human Activities.” Frontiers in Marine Science 1: 32. doi:10.3389/ fmars.2014.00032. Klein, J., and M. Verlaque. 2008. “The Caulerpa racemosa Invasion: A Critical Review.” Marine Pollution Bulletin 56: 205–225. Mannino, A. M., and P. Balistreri. 2017. “An Updated Overview of Invasive Caulerpa Taxa in Sicily and Circum-Sicilian Islands, Strategic Zones within the NW Mediterranean Sea.” Flora Mediterranea 27: 221–240. Mannino, A. M., P. Balistreri, and M. B. Yokeş. 2014. “First Record of Aplysia dactylomela (Opisthobranchia, Aplysiidae) from the Egadi Islands (Western Sicily).” Marine Biodiversity Record 7: e22. doi:10.1017/S1755267214000190. Mannino, A. M., S. Donati, and P. Balistreri. 2016. “The Project ‘Caulerpa cylindracea in the Egadi Islands’: Citizens and Scientists Working Together to Monitor Marine Alien Species.” Biodiversity Journal 7 (4): 907–912. Mannino, A. M., M. Parasporo, F. Crocetta, and P. Balistreri. 2017. “An Updated Overview of the Marine Alien and Cryptogenic Species from the Egadi Islands Marine Protected Area (Italy).” Marine Biodiversity 47: 469–480. Matijević, S., D. Bogner, N. Bojanić, A. Žuljević, M. Despalatović, B. Antolić, V. Nikolić, and J. Bilić. 2013. “Biogeochemical Characteristics of Sediments under the Canopy of Invasive Alga Caulerpa racemosa var. cylindracea (Pelješac Peninsula, Adriatic Sea).” Fresenius Environmental Bulletin 22: 3030–3040. Monaco, A., and P. Genovesi. 2014. European Guidelines on Protected Areas and Invasive Alien Species, Council of Europe, Strasbourg, Regional Parks Agency – Lazio Region. Rome. Mytilineou, C., E. Akel, N. Babali, P. Balistreri, M. Bariche, Y. Boyaci et al. 2016. “New Mediterranean Biodiversity Records (November, 2016).” Mediterranean Marine Science 17 (3): 794–821. Occhipinti-Ambrogi, A., A. Marchini, G. Cantone, A. Castelli, C. Chimenz, M. Cormaci, et al. 2011a. “Alien Species along the Italian Coasts: An Overview.” Biological Invasions 13: 215–237. Occhipinti-Ambrogi, A., A. Marchini, G. Cantone, A. Castelli, C. Chimenz, M. Cormaci, et al. 2011b. “Erratum to: Alien Species along the Italian Coasts: An Overview.” Biological Invasions 13: 531–532. Otero, M., E. Cebrian, P. Francour, B. Galil B, and D. Savini. 2013. Monitoring Marine Invasive Species in Mediterranean Marine Protected Areas (MPAs): a Strategy and Practical Guide for Managers. Malaga (Spain): IUCN. Papini, A., S. Mosti, and U. Santosuosso. 2013. “Tracking the Origin of the Invading Caulerpa (Caulerpales, Chlorophyta) with Geographic Profiling, a Criminological Technique for a Killer Alga.” Biological Invasions 15: 1613–1621. Schembri, P. J., J. Barbara, A. Deidun, E. Lanfranco, and S. Lanfranco. 2015. “It Was Only a Matter of Time: Occurrence of Caulerpa taxifolia (Vahl) C. Agardh var. distichophylla (Sonder) Verlaque, Huisman and Procaccini in the Maltese Islands (Chlorophyta, Ulvophyceae, Caulerpaceae).” BioInvasions Records 4 (1): 9–16.

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Vergés, A., P. D. Steinberg, M. E. Hay, A. G. Poore, A. H. Campbell, E. Ballesteros, et al. 2014. “The Tropicalization of Temperate Marine Ecosystems: Climate-Mediated Changes in Herbivory and Community Phase Shifts.” Proceedings Biological Sciences 281: 20140846. doi:10.1098/ rspb.2014.0846. Vergés, A., C. Doropoulos, H. A. Malcolm, M. Skye, M. GarciaPizá, E. M. Marzinelli, et al. 2016. “Long-Term Empirical Evidence of Ocean Warming Leading to Tropicalization of Fish Communities, Increased Herbivory, and Loss of Kelp.” Proceedings of the National Academy of Sciences U.S.a. 113: 13791–13796.

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Verlaque, M., S. Ruitton, F. Mineur, and C. F. Boudouresque. 2015. “Vol. 4 Macrophytes. in: Briand F. 2015. CIESM Atlas of Exotic Species in the Mediterranean.” CIESM Publ., Monaco, 1–364. Wallentinus, I., and C. D. Nyberg. 2007. “Introduced Marine Organisms as Habitats Modifiers.” Marine Pollution Bulletin 55: 323–332. Zenetos, A., S. Gofas, C. Morri, A. Rosso, D. Violanti, J. E. García Raso, et al. 2012. “Alien Species in the Mediterranean Sea by 2012. a Contribution to the Application of European Union’s Marine Strategy Framework Directive (MSFD). Part 2. Patterns in Introduction Trends and Pathways.” Mediterranean Marine Science 13: 328–352.