Assemblages of sessile marine invertebrates:still changing after all these years?

Abstract

The fouling organisms on Port Bonython pier, South Australia, had previously been monitored for 6.5 yr after initial immersion of piles using photographs of fixed positions and direct observation by divers. Up to that date it appeared that predictions based on experiments at more sheltered sites had not been fulfilled. In particular, the assemblage had not become dominated by modular organisms The rate of change seemed to be slowing after 6.5 yr but this could not be tested. The assemblage on the piles was re-examined in December 1995, after a further 7 yr. Faunal composition differed at sites along the pier throughout the study, and still did so after 13.5 yr, but the composition at all sites tended to change in a similar way through time; positions differed in a consistent way at 6.5 and 13.5 yr, probably reflecting consistent environmental differences between sites along the pier. Abundances of key taxa fluctuated markedly from site to site at any one time, and through time. As originally predicted, after 13.5 yr much of the pile surface area had become covered by encrusting or mound-forming modular animals (54%), especially sponges, and by foliose red algae (25%), unitary organisms such as bivalves and solitary ascidians had become greatly reduced in abundance. It is now clear that the overall composition of the assemblage had not converged to a 'stable' condition by 6.5 yr; more sampling dates would be needed to determine whether it had done so by 13.5 yr

Extending the generality of ecological models to artificial floating habitats

“…Predation (e.g., Connell & Anderson, 1999;Fairweather, 1988;Keough & Butler, 1979;Menge & Sutherland, 1976;Paine, 1966), competition and overgrowth among sessile organisms (e.g., Butler & Connolly, 1999;Connell, 1961;Jernakoff, 1985;Kay & Keough, 1981;Keough, 1984;Miles & Meslow, 1990) may be important factors in determining the distribution of Hydroides spp. on the sides of pontoons.…”

Fauna asociada a la nacra <i>Pinna nobilis</i> (Mollusca: Bivalvia) en la costa norte y este de Túnez

“…Sessile species, on the other hand, disperse mainly at larval or propagule stages and their distribution is more subject to the so-called "priority" effect. Several studies have demonstrated the highly variable distribution of sessile species on hard substrata, last but not least affected by stochastic events (Butler and connolly, 1999). the spatial turnover of such species is therefore more insensitive to patch size, whereas it decreases at larger scale as a possible consequence of the unsaturated "local" vs. "regional" space.…”

Effects of an introduced polychaete, Sabella spallanzanii, on the development of epifaunal assemblages

“…McDougal 1943, Osman 1977, Sutherland & Karlson 1977, Keough & Butler 1979, Kay & Keough 1981, Keough 1984a,b, Anderson & Underwood 1994, Osman & Whitlatch 1995a,b, Brown & Swearingen 1998, Butler & Connolly 1999, Glasby 2000. Therefore the processes structuring these assemblages are probably as well understood as those of any ecological assemblage.…”