Distribution, Population Structure, ­Population Biomass and 
Morphological Characteristics 
of the Tunicate Pyura stolonifera
in the Bay of Antofagasta, Chile

Abstract

Abstract. The present study analyzes the distribution, population structure, population biomass and morphological characteristics of the intertidal tunicate Pyura stolonifera (Heller, 1878) in the Bay of Antofagasta, Chile, where the species shows a reduced geographical range extending around 60 – 70 km. Three sites along its distribution were studied. At the central site the tunicate presents the widest intertidal belts, reaching nearly 11 m (the mid‐intertidal‐Pyura‐zone shows the higher percent cover). Population dry biomass here averaged up to 20.45 kg·m–2, representing one of the highest intertidal specific biomasses reported in the literature. Lower values occur towards the borders of its distribution. Population densities were over 1800 indiv.·m–2 at mid‐intertidal‐Pyura‐belts. Crowding and competition potentially affect morphological characteristics and the energy/tissue allocation along the intertidal and geographical gradient of P. stolonifera.

Invasion of a rocky intertidal shore by the tunicate Pyura praeputialis in the Bay of Antofagasta, Chile

“…This result suggests that the plastic cylinder transplant devices may be equivalent to protection by matrix tunicates and͞or similar to natural rock crevices or upright structures (coralline algae, plastic brushes) (44), where newly arriving P. praeputialis tend to settle and establish. The arrival of P. praeputialis to Antofagasta has resulted in a unique rocky intertidal seascape with P. praeputialis densities of Ͼ1,800 individuals ϫ m at the center of the bay (41). We experimentally tested hypotheses regarding the capacity of P. praeputialis to survive and grow at different sites and tidal heights inside and outside the bay of Antofagasta, and of its competitive performance regarding the abundant native mussel Perumytilus.…”

Patch recolonization by the tunicate Pyura praeputialis in the rocky intertidal of the Bay of Antofagasta, Chile: evidence for self-facilitation mechanisms

“…This must also be considered a probable source of uncertainty in the estimation of parameters for the asymptotic model. The observed recolonization rates can in part be explained by the differences in adult abundance between Las Conchillas and the other 2 localities (see Castilla et al 2000 for information on density and biomass in these localities). As reported by Castilla et al (2000), Las Conchillas has the lowest density and biomass of adults of all 3 localities.…”

“…The observed recolonization rates can in part be explained by the differences in adult abundance between Las Conchillas and the other 2 localities (see Castilla et al 2000 for information on density and biomass in these localities). As reported by Castilla et al (2000), Las Conchillas has the lowest density and biomass of adults of all 3 localities. For species in which the time between larval release and settlement is relatively short (see Clarke et al 1999 for information on Pyura praeputialis) we would expect the abundance of recruits, and therefore recolonization rate, to be related to the local abundance of adults.…”

“…At each of the experimental localities, replicate 40 × 60 cm quadrats were haphazardly chosen at 3 vertical levels, as described in Castilla et al (2000): the upper, mid and lower vertical limits of Pyura praeputialis. All quadrats were photographed (except at Las Conchillas) and then cleared of all erect organisms with a chisel.…”

Biography of Juan Carlos Castilla

“…An Unusual Settlement While continuing his studies on comanagement and his ongoing work at Las Cruces, Castilla has collected many other interests along the Chilean shoreline. For example, in his Inaugural Article (4), he investigates why a particular nonindigenous tunicate settlement exists only within a 60-to 70-km patch of Chile's Bay of Antofagasta (4,26,27) and is not more widely dispersed along the coast. In his early research with Patricio Sanchez, Castilla had noticed the tunicate species Pyura praeputialis distributed exclusively along 60-70 km of coast.…”