Article

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: 1.84). 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.

1 Bookmark
 · 
75 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Coralligenous habitats are of special interest in the Mediterranean Sea because they represent one of the most important biodiversity ‘hot-spots’ and are considered of great relevance for fisheries activities in the region. Despite their importance, however, there are missing consensual methodologies for their monitoring and, despite some attempts, no environmental or ecological quality indices have been established yet. This situation could be related to the difficulties associated with their exploration and their spatial heterogeneity. These habitats are in urgent need of efficient standard monitoring and management protocols programmes to develop an effective network for their conservation. Here we reviewed the available methodologies and robotics tools used to evaluate and monitor benthic habitats, highlighting the importance of defining rapid cost-effective sampling and analyses approaches and architectures for future monitoring of changes in coralligenous habitats based on current technological developments. We identified still images acquisitions as the most effective data gathering system. Stereo photogrammetry, photomosaic elaboration and three-dimensional (3D) modelling may largely improve the data analysis and therefore the quality status assessment of the coralligenous habitats. The advantage and efficiency of different approaches and methods, and whether they should be applied and standardised for further monitoring activities, were discussed.
    Advances in Oceanography and Limnology. 11/2013; 4(2):102-119.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Despite the great contribution of coralligenous communities to Mediterranean biodiversity (second key-ecosystem after Posidonia oceanica meadows), they were never considered in the establishment of multimetric indices for ecological status assessment of marine environment. In this paper, we describe a method to evaluate the ecological status of coralligenous assemblages along Mediterranean French coasts. Several metrics were selected from literature for coralligenous assemblage description and include functional and structural information: percent cover of visible non-vagile species (using photographic quadrats along a transect) and gorgonian demography. Thirty eight field stations were sampled for these metrics in PACA (Provence-Alpes-Côte-d’Azur) region in June 2010 and considered for their morphology (bank, rim), geographical orientation and principal current direction (North, East, West, South) and depth (from −30 to −84 m). Metrics found to be linked to human pressures using ANCOVA and multiple correlation matrix were selected to be included in the index. The index (Coralligenous Assemblage Index, CAI) that we proposed was based on three selected metrics (Bryozoa percent cover, sludge percent cover, builder species percent cover) and considers depth; it was positively and significantly linked to anthropization (related to water quality). The 38 stations studied with theoretically good to bad environmental conditions were classified in levels of status in accordance with our field work knowledge. CAI variation was validated with three stations sampled with 30 other photos. This index could be an effective tool for the assessment of the ecological quality of coralligenous communities. It could be applied in the context of the Marine Strategy Framework Directive as well as in conservation and sustainable management of the marine environment.
    Ecological Indicators 09/2012; 20:345–352. · 3.23 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to analyze the interaction of a non‐native macroalga (Acanthophora spicifera) with native macroalgae (Sargassum spp.) and sponge assemblages in a subtropical embayment of the Mexican Pacific. The intensity of A. spicifera epiphytism on the native seaweed Sargassum varied significantly over time and was inversely related to the Sargassum density and size. The higher intensity (up to 28 individuals per host plant) occurred when Sargassum was smaller and was lower in density (senescence period). The lower intensity was recorded during the growth period of Sargassum and the subsequent increase in intensity was attributed to a high fragmentation period of A. spicifera, which was evidenced by a decrease in its average size and biomass and by the presence of larger free‐floating accumulations on the subtidal zone. The facultative interaction between A. spicifera and Sargassum appears to be neutral, as no negative or positive effects were found for epiphytic or basibiont seaweeds. However, this invasive seaweed characteristically monopolizes almost all types of hard substrate, and its effects on other algae and benthic organisms should be investigated. Moreover, A. spicifera was often epizoic on epilithic sponges. This invasive seaweed was found anchored on the sponge tissue by rhizome‐like structures. In addition, free‐floating fronds of A. spicifera were frequently found carrying small pieces of the basibiont sponge in its basis (60% of them with eggs and embryos), which suggests a novel facilitation mechanism for some sponge species, as the A. spicifera epizoism could favor fragmentation, dispersal and recruitment of these invertebrates. This study shows that A. spicifera is not only a species that adapts rapidly to the new conditions of the receiving environment but, due to its epibiotic traits, it can directly interact with and influence the life histories of some native species.
    Marine Ecology 01/2012; 33(4):470–480. · 1.84 Impact Factor

Full-text (2 Sources)

Download
28 Downloads
Available from
Jun 5, 2014