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    Topic review

    Invasive Seaweeds

    Subjects: Others
    View times: 232
    Submitted by: Leonel Pereira

    Definition

    According to the International Union for Conservation of Nature (IUCN), an “invasive alien species” is an exotic species that establishes itself in a natural or semi-natural ecosystem or habitat, becoming an agent of change and a threat to diversity native biological.

    Therefore, invasive species are those capable of successfully reproducing and forming self-sufficient populations in an ecosystem that is not theirs. When this happens, we say that they have "naturalized", which can have disastrous consequences for native (native) species.

    Some invasive alien species are unable to survive and reproduce on their own, so they end up disappearing from the ecosystem and do not endanger native biodiversity. In this case, they are not considered invasive species, only introduced.

    1. Introduction

    Seaweeds' ecological relevance has been acknowledged by the scientific community through the assessment of the ecosystem services they provide, which directly or indirectly support human well-being, namely regulating, provisioning, and cultural services [1][2].

    Algae play a pivotal regulatory role in the aquatic environment, being sources of primary and secondary production, providing protection to coastal zones, and as nursery areas [3]. Moreover, seaweeds are a food source for many aquatic organisms, supporting provisioning services for a wide range of invertebrates [4]. Furthermore, seaweeds are part of cultural heritage and distinctiveness in each area, presenting economic value for society [5].

    However, these ecosystems are currently under threat due to climatic changes, such as ocean acidification or the increasing seawater temperature [6]. Despite that, anthropogenic pollution nodes are major stressors that affect the structure and functioning of aquatic environments. For instance, eutrophication is a phenomenon provoked by the discharge of effluents with a high inorganic load (i.e., phosphorus, nitrogen, nitrate, nitrite) that can lead to eutrophication. Thus, the excess of nutrients will lead to the occurrence of algal blooms, giving an advantage to opportunistic algae that will affect the structure of the community and its primary productivity [7]. Regarding the available resources, non-indigenous species (NIS) usually are more effective when using them than native species [8]. However, NIS presence can have negative, positive, or neutral effects on the ecosystems where they are integrated [9]. Still, the introduction of exotic species in marine ecosystems can often lead to severe changes in ecosystem functioning. Among the vectors which favored the introduction of exotic seaweeds related to marine traffic rising [10] are, namely, through the discharge of ballast waters and biofouling on recreational boats or cargo ships hulls [11][12][13]. Another possible introduction vector is associated with the aquaculture, importation, and commercialization of marine organisms, namely mollusks [14]. Moreover, it is still found exotic and/or invasive species commercially available in the European aquarium trade markets, such as Caulerpa racemosa and Caulerpa taxifolia [15].

    Whenever exotic seaweed species are introduced in a different geographic area and if the biotic and abiotic conditions allow it, these species can exhibit an invasive behavior. Moreover, a set of characteristics are needed to consider it an invasive seaweed species, commonly related to opportunistic traits such, such as a fast growth rate, dynamic life cycle, high recruitment rate, physiology, size, and fitness [3][16][17][18]. However, the intrinsic mechanisms associated with the biologic invasion's success are not yet fully understood due to their complexity [3]. For these reasons, macroalgal marine invaders are considered a threat to coastal and estuarine environments.

    The Iberian Peninsula macroalgal community has also been a target of the introduction of several exotic seaweed species (Table 1), in which some of them are well established, exhibiting a widespread distribution in this area and invasive behavior.

    Table 1. Exotic seaweed species recorded in the Iberian Peninsula. R–Rhodophyta; O–Ochrophyta; C–Chlorophyta.

    Phylum

    Species

    Spain

    Portugal

    Native Habitat

    References

    R

    Acrothamnion preissii (Sonder) E.M. Wollaston 1968

    x

     

    Australia

    [19]

    R

    Agardhiella subulata (C. Agardh) Kraft and M.J. Wynne 1979

    x

     

    Canada

    [20]

    R

    Agarophyton vermiculophyllum (Ohmi) Gurgel, J.N. Norris (formerly Gracilariopsis vermiculophylla Ohmi et Fredericq 2018)

    x

    x

    Japan

    [20][21]

    R

    Asparagopsis armata Harvey 1855

    x

    x

    Australia

    [20][22][23]

    R

    Asparagopsis taxiformis (Delile) Trevisan 1845

    x

    x

    Australia

    [22][23][24]

    R

    Bonnemaisonia hamifera Hariot 1891

    x

    x

    Japan

    [21]

    R

    Botryocladia wrightii (Harvey) W.E. Schmidt, D.L. Ballantine and Fredericq 2017 (formerly Chrysymenia wrightii (Harvey) Yamada 1932)

    x

    x

    Japan

    [20][21]

    R

    Callithamniella flexilis Baardseth 1941

    x

     

    Stoltenhoff Island (South Atlantic)

    [20]

    R

    Contarinia squamariae (Meneghini) Denizot 1968 (formerly Wormskioldia squamariae Meneghini)

     

    x

    -

    [21]

    R

    Dasya sessilis Yamada 1928

    x

    x

    Japan

    [21]

    R

    Dasysiphonia japonica (Yendo) H.–S. Kim 2012

    x

     

    Japan

    [21]

    R

    Falkenbergia rufolanosa (Harvey) F. Schmitz 1897

    x

    x

    Australia

    [20][25]

    R

    Gracilariopsis chorda (Holmes) Ohmi 1958

    x

     

    Japan

    [26]

    R

    Grateloupia filicina (J.V. Lamouroux) C. Agardh 1822

    x

    x

    Australia

    [21]

    R

    Grateloupia subpectinata Holmes 1912

    x

    x

    Japan

    [20][21]

    R

    Grateloupia turuturu Yamada 1941

    x

    x

    Japan

    [21]

    R

    Gulsonia nodulosa (Ercegovic) Feldmann and G. Feldmann 1967

     

    x

    Adriatic

    [21]

    R

    Kapraunia schneideri (Stuercke and Freshwater) A.M. Savoie and G.W.Saunders 2019 (formerly Polysiphonia schneideri B. Stuercke and D.W. Freshwater)

    x

     

    North America (North Carolina)

    [21]

    R

    Lomentaria hakodatensis Yendo 1920

    x

    x

    Japan

    [20]

    R

    Lophocladia lallemandii (Montagne) F. Schmitz 1893.

    x

     

    Egypt (Suez channel)

    [21]

    R

    Melanothamnus harveyi (Bailey) Díaz-Tapia and Maggs 2017 (formerly Neosiphonia harveyi (Bailey) M.-S. Kim, H.-G. Choi, Guiry and G.W. Saunders 2001)

    x

    x

    North America (Connecticut)

    [20][21]

    R

    Pachymeniopsis lanceolata (K. Okamura) Y. Yamada ex S. Kawabata 1954

    x

     

    Japan

    [27]

    R

    Polysiphonia morrowii Harvey 1857

    x

     

    Japan or Korea

    [20]

    R

    Pyropia suborbiculata (Kjellman) J.E. Sutherland, H.G. Choi, M.S. Hwang and W.A. Nelson 2011

    x

    x

    Japan

    [20][21]

    R

    Scageliopsis patens E.M. Wollaston 1981

    x

    x

    Australia

    [20][21]

    R

    Symphyocladia marchantioides (Harvey) Falkenberg 1897

     

    x

    New Zealand

    [20][21]

    R

    Womersleyella setacea (Hollenberg) R.E. Norris 1992

    x

     

    Hawaii

    [21]

    O

    Colpomenia peregrina Sauvageau 1927

    x

    x

    Pacific coast of North America

    [23]

    O

    Dictyota cyanoloma Tronholm, De Clerck, A. Gómez-Garreta and Rull Lluch 2010

    x

     

    Australia

    [19]

    O

    Sargassum muticum (Yendo) Fensholt 1955

    x

    x

    Japan

    [21]

    O

    Scytosiphon dotyi M.J. Wynne 1969

     

    x

    North America (California)

    [21]

    O

    Stypopodium schimperi (Kützing) Verlaque and Boudouresque 1991

    x

     

    Egypt (Sinai Peninsula)

    [21]

    O

    Undaria pinnatifida (Harvey) Suringar 1873

    x

    x

    Japan

    [21]

    O

    Zosterocarpus oedogonium (Meneghini) Bornet 1890

     

    x

    Mediterranean

    [19]

    C

    Caulerpa racemosa (Forsskål) J. Agardh 1873

    x

     

    Australia

    [21]

    C

    Caulerpa taxifolia (M. Vahl) C. Agardh 1817

    x

     

    India

    [19]

    C

    Caulerpa cylindracea Sonder 1845

    x

     

    Australia

    [19]

    C

    Codium arabicum Kützing 1856

     

    x

    Egypt

    [19]

    C

    Codium fragile subsp. fragile (Suringar) Hariot 1889

    x

    x

    Japan

    [21]

    C

    Ulva australis Areschoug 1854

    x

     

    Japan

    [21]

    Against this scenario, it urges the need to mitigate the impacts of seaweeds invasions in coastal and estuarine ecosystems, prioritizing the mapping of exotic seaweed species and comprehend the mechanisms which allow the success or failure of the invasion in order to take control and conservation measures [17][28][29].

    Among the several adaptative advantages of invasive seaweeds, their high growth rate makes them suitable to feedstock supply for industrial exploitation.

    2. Invasive Seaweeds: An Important Feedstock to Food Industry

    2.1. Red Seaweeds

    In marine ecosystems, seaweeds that belong to the phylum Rhodophyta constitute a wide taxonomic diversity [30]. Among the exotic seaweeds registered on the Iberian Peninsula, Pyropia suborbiculata (Kjellman) (J.E. Sutherland, H.G. Choi, M.S. Hwang and W.A. Nelson 2011 it is an Asiatic Bangiales), due to its high tolerance to the variation of physico-chemical conditions, is now widespread throughout the American, Australian, and European shoreline [31][32][33]. However, the first records of P. suborbiculata in the Atlantic Ocean were misidentified with Neopyropia yezoensis M.S. Hwang and H.G. Choi (formerly Pyropia yezoensis) [34]. Through molecular analysis, in 2005, it was possible to genetically distinguish these two seaweed species [35]. More recently, researchers found that P. suborbiculata is well established on the Iberian Peninsula and is genetically similar to the population from the Pacific Ocean, suggesting that the presence of this exotic seaweed in the Northwest Atlantic is probably through marine shipping [31][36]. In contrast, P. suborbiculata is produced through aquaculture and is authorized and considered safe for human consumption in the United States of America [37][38]. In fact, this seaweed can have a significant role in the daily diet (Figure 1) and can be used fresh or dried, milled, and then utilized as a flavor enhancer [39].

    Figure 1. Seaweed (Pyropia sp.) pie with carrot and coconut.

    However, it is in the Asiatic region that this seaweed currently assumes a high economic interest, being considered an important marine crop for food feedstock [40][41]. In these countries, seaweeds which belongs to Pyropia/ Porphyra/ Neopyropia genus are highly consumed by the population [42]. Therefore, P. suborbiculata is also a potential candidate for food industry feedstock due to its protein (11.2% DW), lipids (0.3% DW), and carbohydrates (31.6% DW) content [43].

    The health benefits that this food resource presents, lead to increased customer demand, which allowed a sales volume increase and the global economic expansion of Pyropia/Porphyra commercialization [44].

    Thus, Pyropia/Porphyra/Neopyropia spp. farming became essential to guarantee the feedstock. However, these cultivations are frequently affected by fungal diseases. For instance, the fungi Pythium porphyrae provokes the most concerning disease (red rot disease) in Asiatic Pyropia aquacultures [45][46], causing seaweed blades destruction, precluding the entire cultivation, and leading to serious economic losses [47]. Nevertheless, studies showed that P. suborbiculata is more resistant to P. porphyrae fungal attack [48], thus being a potential candidate for food supply through their cultivation.

    Another introduced red seaweed native from Japan, Agarophyton vermiculophyllum (Ohmi) Gurgel, J.N. Norris et Fredericq 2018 (previously known as Gracilaria vermiculophylla) (Figure 2), has invaded estuaries throughout the whole world. Although the presence of this algae was underrated in several areas due to the morphological similarity with native species Gracilaria gracilis [49], many signs of progress have been made through genetic analysis in order to distinguish them [50][51].