The thicker, and probably more permanent, crusts or reefs seem to have a considerable
influence on the benthic community structure. George & Warwick (1985) mentioned that Sabellaria
reefs contained a more diverse fauna than nearby areas. The National Rivers Authority
(1984) found sites in the Wash (eastern England) associated with Sabellaria spinulosa
to have more than twice as many species and almost three times as many individuals as
sites with very few, or no Sabellaria spinulosa.
Experimental laboratory work by Wilson (1970) showed the Sabellaria spinulosa
larvae are strongly stimulated to metamorphose and settle by cement secretions of adult or
newly settled young Sabellaria spinulosa. In the absence of suitable stimulation
metamorphosis and settlement sometimes occurs but always more slowly. George & Warwick
(1985) suggested that growth and recruitment of Sabellaria spinulosa could be
inhibited or even prevented by dense populations of the brittle star Ophiothrix
fragilis, which occur at very high densities, thus preventing adequate food particles
from reaching the worms.
Keystone (structuring) species
Importance of habitat for other species
Warren & Sheldon (1967) and Warren (1973) reported that Sabellaria spinulosa,
probably along with other associated organisms, could be an important food source for pink
shrimp Panadalus montagui.
Sabellaria spinulosa is a fast-growing annual, as sheets up to 2.4 cm thick can
develop within one growing season. These are definitely seasonal in abundance. Areas where
Sabellaria spinulosa had been lost due to winter storms appeared to recolonise up
to the maximum observed 2.4 cm thickness during the following summer (R. Holt pers comm).
George & Warwick (1985) also made seasonal observations in the Bristol Channel and
concluded that in the year of the study the settlement of juveniles was low and that the
density of adults could not be maintained by the degree of recruitment.
Time for community to reach maturity
George & Warwick (1985) found that the majority of the reef was composed of Sabellaria
spinulosa over one year old. They also mentioned that most of the species found within
the reef matrix are slow growing and long lived with very low turnover rate, suggesting
that the reef itself must be relatively old and stable.