Seasonal non-indigenous species succession in a marine macrofouling invertebrate community

Abstract

We report results from a 2-year study on the succession pattern of macrofouling assemblages in the Taranto Sea, an important alien species hotspot in the Mediterranean Sea. Four sets of PVC panels were used as macrofouling collectors; each unit was installed at a different time (April 2013, July 2013, October 2013 and January 2014) and then surveyed quarterly for 1 year. The macrofouling community consisted of 93 sessile invertebrate species, of which 16 were NIS and five were cryptogenic. In both years non-indigenous species (NIS) recruitment occurred mainly in the quarter July/October in concert with the settlement of pioneer autochthonous species. This recruitment is independent of immersion time, occurring on both bare substrates and on previously colonized panels. This increase in NIS coverage is influenced by the development stage of the community, suggesting that NIS grow better without potential competitors. Two sets of NIS were distinguished. The first included abundant ascidians, serpulids, and bryozoans that are structuring components of early communities when favorable conditions exist (i.e. a lack of competitive autochthonous species). After settlement, these species are unable to develop in laterstage communities. The second set of NIS was composed of sabellid worms that settle in early and late communities but, unlike the other NIS, are able to persist and become dominant in late macrofouling communities independent of seasonal changes.

The role of two non-indigenous serpulid tube worms in shaping artificial hard substrata communities: case study of a fish farm in the central Mediterranean Sea

“…In fact, most of the macrofaunal species showed a visible decrease in abundance during the period dominated by the 2 serpulid species (spring) and a subsequent increase during summer. Our results are con sistent with previous observations by Lezzi et al (2018), which suggested that H. elegans and H. dirampha be have as r-selected pioneer species, structuring components of early communities, but after settlement, they are not able to develop in late communities. We ob served that some sessile components of the community, principally represented by the native serpulid H. dianthus, the sabellid Branchiomma bombyx and the balanid Ba lanus trigonius (NIS according to Zenetos et al 2010), showed a peak of abundance during spring, corresponding with the highest densities of the 2 serpulid NIS in this study.…”

“…We ob served that some sessile components of the community, principally represented by the native serpulid H. dianthus, the sabellid Branchiomma bombyx and the balanid Ba lanus trigonius (NIS according to Zenetos et al 2010), showed a peak of abundance during spring, corresponding with the highest densities of the 2 serpulid NIS in this study. This suggests that sessile NIS recruitment on hard substrate can co-occur with that of other sessile species (Lezzi et al 2018), and that H. elegans and H. dirampha are able to settle despite high competition for space with other sessile organisms during their recruitment. On the other hand, the 47 Fig.…”

“…Although some authors have recently focused on the study of seasonal NIS succession and macrofouling community development (Lezzi et al 2018, Martell et al 2018, to date, the facilitation processes that regulate the spatial and temporal settlement, growth, population size and features of NIS are poorly known, especially in a Mediterranean context . Within fouling communities, more attention has been paid to sessile NIS, including a various array of solitary and colonial marine invertebrates (e.g.…”

“…Within fouling communities, more attention has been paid to sessile NIS, including a various array of solitary and colonial marine invertebrates (e.g. ascidians, bryozoans, bivalve molluscs, tube-building polychaete worms, sponges, barnacles and sea anemones; Wallentinus & Nyberg 2007, Lezzi et al 2018, Sarà et al 2018a). These organisms not only shape local metabolic and trophic interactions, by altering the physical or biological environment in the system, they can exert a strong habitat-modifying effect, making it more suitable for some species and less so for others (Stachowicz et al 2002, Floerl et al 2004, Sarà et al 2018a.…”

Seasonal and bathymetric effects on macrofouling invertebrates’ primary succession in a mediterraenan non-indigenous species hotspot area

“…We investigated the macrofouling succession in the Gulf of Taranto (Central Mediterranean Sea), an area recently attracting interest due to the establishment of numerous non-indigenous species (NIS) (Gravili et al, 2010;Occhipinti-Ambrogi et al, 2011), and where fouling assemblages seem to be dominated mainly by filter feeder invertebrates (Pierri et al, 2010). In particular, we examined succession on artificial substrates in exper-iments conducted in the Mar Grande of Taranto (Central Mediterranean Sea), a wide confined area recently attracting interest due to the establishment of numerous non-indigenous species (NIS) (Gravili et al, 2010;Occhipinti-Ambrogi et al, 2011;Lezzi et al, 2017).…”