Effects of the spread of the alga Caulerpa racemosa var. cylindracea on the sponge assemblage from coralligenous concretions of the Apulian coast (Ionian Sea, Italy)

Dipartimento di Zoologia, Università degli Studi di Bari, Bari, Italy
Marine Ecology (Impact Factor: 1.08). 08/2009; 30(3):337 - 345. DOI: 10.1111/j.1439-0485.2009.00282.x

ABSTRACT The present work investigated the modifications induced by the spread of the green macroalga Caulerpa racemosa var. cylindracea (Bryopsidales, Chlorophyta) on the sponge assemblage of Apulian coralligenous concretions (Ionian Sea – Torre Ovo, Italy). The study of qualitative and quantitative sponge composition was carried out before (2004) and after (2006) the spread of this invasive alga by means of traditional (quadrat scraping) and photographic sampling methods. Results indicate that the spread of the green alga is concomitant with a significant decrease in percentage sponge cover both on horizontal- and on vertical-oriented substrates. In addition, strong modifications to the structure of the community in terms of repartition of the available substrate have been observed since the algal spread. Conversely, no major changes have affected the specific composition of the sponge assemblage, suggesting that at this stage of colonization the algal spread has not produced a loss of sponge biodiversity. However, there is a clear need to monitor closely the C. racemosa invasion to verify its long-term impact on the sponge assemblage.

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Available from: Giuseppe Corriero, Sep 26, 2015
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    • "The species has been reported from all kinds of substrata and depths, as part of a variety of benthic assemblages, and thrives in disturbed habitats of the heavily urbanized Mediterranean coastlines [30,32]. Invasive populations of C. cylindracea establish dense and compact monospecific stands, which easily overgrow and outcompete and/or negatively impact other seaweed [33,34], seagrass [35] and invertebrate species [36,37] leading to biotic homogenization [38] and an overall decrease of species diversity in affected areas [30]. To date only partial recovery of the assemblages could be observed after eradication of C. cylindracea in Italy and France [33,39]. "
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    PLoS ONE 06/2013; 8(6):e68337. DOI:10.1371/journal.pone.0068337 · 3.23 Impact Factor
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    • "For these reasons and because they cumulate study constraints such as various systems, slow dynamics, and more importantly presence at generally high depths limiting work time underwater, coralligenous assemblages are relatively poorly understood at the community level (Kipson et al., 2011). Saving time underwater is one of the advantages of photographic methods that are more and more frequently used (Balata et al., 2005; Baldacconi and Corriero, 2009; Deter et al., 2012; Ferdeghini et al., 2000; Kipson et al., 2011; Virgilio et al., 2006). They allowed counting the number of species and/or estimating species abundance using percent cover. "
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    • "Most previous studies of the response of native fauna to invasive seaweeds have only described effects on the diversity or abundance of species. Only few of these studies have assessed the direct effects on fauna (Williams and Smith 2007; Wright and Gribben 2008; Thomsen et al. 2009; Baldacconi and Corriero 2009; Zuljevic et al. 2011; Linares et al. 2012). Our manipulative experiments unequivocally established a cause-effect relationship between invasive seaweeds and a decline in native fauna. "
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