Abstract

RAMIREZ-CALERO, Sandra et al. Invasion of a native polychaete in an Eastern Tropical Pacific island. Bol. Invest. Mar. Cost. [online]. 2017, vol.46, n.2, pp.135-151. ISSN 0122-9761.  https://doi.org/10.25268/bimc.invemar.2017.46.2.731.

Fluctuations in population dynamics, like demographic expansions and invasions, are relatively common in ecosystems, and in certain cases may affect biodiversity and a suite of other ecological attributes. In this paper, we report the appearance and population explosion of the reef-building polychaete (Sabellariidae) Idanthyrsus cf. cretus in Gorgona Island (Eastern Tropical Pacific), describing some ecological characteristics (abundance and coverage). The survey was carried out in three study areas of Gorgona Island, located in the Colombian Pacific. Sampling was performed randomly at low, mid and high intertidal levels, in order to measure density and coverage. Density was measured randomly in three study areas at low, mid and high intertidal levels collecting samples (N=37) of 100 cm2 from the colony. Coverage was measured using random transects (N=21) per locality and intertidal levels (20 m length × 1 m width). A total of 1,904 I. cf. cretus were collected with a mean density of 73 ind./100 cm2. Coverage was statistically different between intertidal zones, with the highest values in the mid-intertidal level (11%). Differences in coverage of I. cf. cretus colonies among study areas are probably due to differing intertidal physical characteristics: the availability of adequate substrate and building materials in the study areas sediments, which in turn might affect abundance and colony size. Suitable substrate and construction material might have favored the rapid spreading and local invasion of this species.

Keywords : Demographic explosion; Biological engineer; Invasion; Idanthyrsus.

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